The biogenesis of miRNA starts from the nucleus, more precisely from sequences of DNA usually referred to as miRNA genes that are exclusively transcribed as miRNA transcripts, as shown in Figure 1 . The final target of these miRNA transcripts can be the intronic or the untranslated region of a protein-coding gene. Previous studies have pointed to the canonical and non-canonical pathways as the major ones for illustrating the biogenesis of the miRNAs (1). Regarding the canonical pathway implied for the biogenesis of miRNA, the process initiates from the nucleus by transcribing the miRNA genes to give their relevant primary miRNAs with the help of polymerase III (24). The primary miRNAs comprise 60 to 80 nucleotides with a hairpin stem-loop structure. Following transcription comes the microprocessor complex that cleaves primary miRNAs to yield precursor miRNA (pre-miRNAs), which are around 22 base pair stems with 3′ 2 nucleotides that are overhang. The microprocessor complex is commonly referred to as “Drosha-DGCR8”, where Drosha acts as an RNase enzyme and DGCR8 is an RNA binding protein that stands for DiGeorge Syndrome Critical Region 8 (1, 2). The process then shifts from the nucleus to the cytoplasm with the contribution of Exportin 5, which exports pre-miRNAs to the cytoplasm to meet with the dicer. At this point, pre-miRNAs are processed by dicer, an RNase III endonuclease, which cleaves the hairpin structure to remove the terminal loop. This cleavage generates a short double-stranded RNA molecule known as the miRNA duplex. Then comes the big role of the RNA-induced silencing complex (RISC), which is assembled as a multiprotein complex comprising of the miRNA duplexes, Argonaute RISC Catalytic Component 2 (Ago2), and several other proteins all working together synergistically as a machine. Here, the miRNA duplexes are subjected to a final cleavage step by the Ago2, leaving a single-stranded miRNA that functions as a guide strand to scan mRNAs in the cytoplasm for potential complementarity, whereas the other strand gets degraded. In most cases, complementarity occurs in the 3’untranslated region (3’UTR) of mRNAs. Other less common complementarity cases have been reported, and they are found to be associated with not only the 5’UTR mRNA region but also the protein-coding ones (25). Finally, the guide strand reaches out to its target and is followed by either translation repression or degradation of the relevant protein (26). Other non-canonical miRNA biogenesis pathways have recently been revealed that are not dependent on either the microprocessor complex or dicer. To further illustrate, miRtrons does not include the microprocessor complex, as pri-miRNAs are spliced instead. Other scenarios emerge that happen to surpass the dicer and are routed directly to Ago2, in which case the stem-loop is too short to be recognized by the dicer (1).

lncRNAs, unlike miRNA, are long RNA transcripts found to exceed 200 nucleotides that do not get translated into protein (non-coding transcripts). The biogenesis process is like that of miRNA, but it has some distinctive characteristics. First of all, both RNA polymerase II and III can initiate the transcription process depending on the associated promoter sequence, as shown in Figure 1 (27). lncRNAs are further clustered according to their gene location, which is different from protein-coding ones. Grouping scenarios involve inter or intra-genic lncRNAs. The latter is identified as sense or antisense based on the orientation associated with the overlap condition. There are also intronic or overlapped ones with genes that code for proteins (28). The transcription process involved in lncRNAs is mostly under the control of enhancers or promoters to regulate its function. Following transcription, transcripts are processed by splicing, capping, and poly-A tail addition. Not to mention, the transcripts generated affect the expression of other genes. As a result, the majority of lncRNAs serve as regulatory elements, with a subset of lncRNAs being converted into miRNAs or piRNAs, which also play regulatory roles. Interestingly, the function of the lncRNAs dictates the place it localizes, where it is either directed to the nucleus or the cytoplasm. To elaborate, localization directed to the nucleus is typically involved in the process of chromatin-modifying complexes. In contrast, those directed to the cytoplasm are involved in the interaction with not only mRNA but also proteins as a part of the post-transcriptional regulation (3). As an example of nuclear localization, chromatin remodeling is portrayed in the role of XIST lncRNA to inactivate the X-chromosome by alterations in the gene expression of genes associated with X chromosomes (29). Another type of nuclear control is epigenetic regulation, which occurs when lncRNAs interact with histone proteins, methyl transferase enzymes, and transcription factors to activate or otherwise repress gene expression. Thus, lncRNAs can also have a role in the transcription process by working as a repressor or enhancer in collaboration with transcription factors or other RNA-binding proteins (30). Cytoplasmic localization, on the other hand, is concerned with post-transcriptional regulation, involving the interaction of lncRNAs with either mRNA, altering its stability, or with miRNA, inhibiting their translational repression role of target mRNA (31).

Concerning circRNAs, non-canonical splicing drives the formation of circRNAs in human cells by the back-splicing mechanism, resulting in a closed-loop structure held by a covalent bond, as illustrated in Figure 1 . Such circular structure has several add-ons compared to linear RNAs, including excellent stability and resistance to exo-nuclease degradative activity (4).,When it comes to the biogenesis process, circRNAs follow two distinguished pathways: spliceosome-mediated back-splicing and lariat-driven circularization. Regarding the spliceosome-mediated back-splicing, exons forming the pre-mRNA are joined in a way that the 5’end of the final exon undergoes back-splicing to an initial exon’s 3’ end, forming the circular structure. This gives a covalently bonded circular loop made up entirely of exons, and no introns are included in such a pathway, resulting in enhanced stability (32, 33). The lariat-driven circularization, on the other hand, includes both exons and introns and hence is stable but less stable than the other pathway due to the presence of introns. The lariat structure is seen during the normal splicing process in case the 5’ end of an intron is connected to a branching point inside the intronic area. The lariat’s 3’ end connects back to its 5’ as an alternative to degradation, forming a circular structure (34, 35). circRNAs function in several processes on the cellular level, where they work as a sponge for miRNAs to regulate gene expression (36). circRNAs are not simply regulatory elements; they have also been proven to interact with other proteins and translate into proteins (37).

Abnormal expression of miRNA is observed in nearly all forms of human cancer, where they can significantly interfere with cell signaling pathways, affecting the onset and progression of cancer (41). Specific regulatory functions of miRNAs reveal modulation of important gene expression linked to the cancer cell cycle, apoptosis, and migration (42). The impact of miRNAs on cancer can primarily be observed in three ways: as tumor suppressors, as oncogenes, and by either promoting or inhibiting cancer metastasis (43). In chronic B-cell lymphocytic leukemia (B-CLL), miR-29 functions as a tumor suppressor that inhibits cancer progression; yet, it is also enhanced in acute myeloid leukemia and more aggressive types of B-CLL, suggesting that it may also have an oncogenic role (39). Certain miRNAs can prevent normal cells from transforming into cancerous ones. Their expression is often downregulated in cancer compared to normal cells (44). For example, let-7 is a tumor suppressor usually downregulated in cervical, breast, and lung cancers. Let-7 inhibits the RAS family associated with approximately one-third of human cancers (45, 46). Similarly, miR-15a/miR-16-1 is downregulated in CLL (47). The miR-34 family, which consists of the three members miR-34a, miR-34b, and miR-34c, is the first family of known tumor suppressors that works together with the tumor suppressor gene p53 (48–50). Both miR-34a and miR-34b can inhibit cancer cell invasion and metastasis, whereas miR-34a is downregulated in rectal cancer (51, 52). Additionally, miR-34 negatively regulates the Wnt signaling pathway, leading to an inhibition of the epithelial-mesenchymal transition (EMT) process, which is linked to invasion and migration. miR-34 is found to have lower expression levels in prostate cancer and downregulated in multiple myeloma, osteosarcoma, breast, and gastrointestinal cancers (39, 50, 53).

When acting as oncogenes, miRNAs are upregulated in cancer cells to promote proliferation and metastasis or inhibit tumor suppressor activities (54). For instance, miR-155 contributes to lymphoma development by facilitating abnormal B cell proliferation (55). Another example is miR-21, which functions as an oncogenic miRNA by downregulating tumor suppressor genes, hence contributing to tumorigenesis (56). miR-21 is upregulated across numerous cancer types, and its overexpression induces pre-B-cell lymphoma in murine models and activates the Ras/MEK/ERK signaling pathway, leading to KRAS-dependent carcinogenesis (57, 58). Also, miR-17-92 cistron is upregulated in several lymphoma types and collaborates with the oncogenic factor c-myc to enhance cancer development (59). Additionally, LATS2, a tumor suppressor gene, is downregulated by miR-372 and miR-373 to balance wild-type TP53, consequently interacting with RAS and promoting cellular proliferation and tumorigenesis as part of the mechanism underlying human testicular germ cell tumorigenesis (39). RAS mutations are substantial contributors to cancer development, with altered RAS genes allowing the RAS protein to remain active, thereby regulating cancer cell proliferation, metabolism, apoptosis, and angiogenesis through downstream MAPK, PI3K, and other signaling pathways (60, 61). Moreover, non-canonical miRNAs are found to be associated with tumor formation and progression of the disease in major cancer types. An example is pre-miR-451, which is downregulated in cancer of the epithelial cells of different organs involving the lung and colon (1).

Besides their direct roles in promoting or inhibiting cancer, miRNAs can also influence cancer metastasis by promoting the growth and expansion of the primary tumor, invasion of surrounding tissues, and penetration into lymphatic and blood vessels (62, 63). Additionally, tumor thrombi may migrate through lymph and blood, ultimately extravasating and invading distant tissues, where cancer cells can proliferate and establish metastasis (64). Research has identified several miRNAs that promote cancer metastasis. For example, the upregulation of miR-10b enhances breast cancer metastasis (65). Additionally, induction of exosomal miR-21 and miR-10b by the acidic TME of the liver can promote both liver cancer cell proliferation and metastasis (39, 66). Moreover, miRNAs have been shown to play a role in inhibiting cancer metastasis. For instance, miR-335 directly inhibits the production of SOX4, a transcription factor involved in the development and migration of cellular progenitors, therefore preventing breast cancer metastasis (67). Additionally, miR-126 targets CRK37, a protein involved in actin remodeling and an adaptor in signaling for focal adhesion formation and cell migration, and can hence suppress cancer cell adhesion, migration, and invasion (39, 68). Furthermore, miR-146a downregulates Rock1 expression, which is significant for morphogenesis and hyaluronan-mediated transformation and metastasis of hormone-refractory prostate cancer in vivo (39). Therefore, miRNAs have the potential to serve as biomarkers for differentiating metastatic and non-metastatic cancers (41, 69, 70). For example, miR-10b can effectively differentiate between metastatic melanoma and its non-metastatic counterpart (39).

miRNAs also play a significant role in modulating alternative splicing (AS) by targeting splicing factors (SFs) or RNA-binding proteins (RBPs) in cancer (71). For example, miR-133b inhibits SF3B4 mRNA translation, leading to a disruption of SF3B4-regulated AS and, limitation in hepatocellular carcinoma (HCC) cell proliferation and metastasis (72). Similarly, miR-200c and miR-375 exert translational repression on Quaking (QKI), an RBP, which affects QKI-mediated AS and consequently influences the plasticity of cancer-associated epithelial cells (71). Furthermore, the miR-212/hnRNPH1 axis plays a role in prostate tumorigenesis by downregulating the expression of the androgen receptor (AR) and its splice variant AR3 (73). Specific miRNAs, including miR-21, miR-106a, miR-126, miR-155, miR-182, miR-210, and miR-424, are critical regulators of tumor angiogenesis (74). miR-21, miR-126, and miR-93 enhance the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1 (HIF-1) by targeting phosphatase and tensin homolog (PTEN) and inhibiting the angiogenesis inhibitor thrombospondin-1 (THBS1) (75, 76). Additionally, miRNAs can interact with lncRNAs, such as MALAT1, to inhibit large tumor suppressor 2 (LATS2), thereby regulating cancer cell growth, invasion, and metastasis (74, 77).

Cancer development is well characterized by abnormal glucose metabolism. Typically, normal tissues depend on aerobic oxidative phosphorylation to generate energy but switch to anaerobic glycolysis during hypoxic conditions. In contrast, cancer cells predominantly rely on aerobic glycolysis, even with sufficient oxygen (78–80). Numerous ncRNAs involved in glucose metabolism are dysregulated in various cancers. This dysregulation can lead to mitochondrial dysfunction, enhanced activity of key enzymes, altered isozyme profiles, and disrupted glucose metabolic signaling pathways (81). Regarding ncRNAs and glucose uptake, GLUT is a crucial transporter of glucose —the abnormal expression of GLUT1 results from the dysregulation of ncRNAs in cancer, including miR-181a and let-7a-5p. Increased expression of miR-181a has been associated with increased metastasis in colorectal cancer (CRC) by inhibiting PTEN expression while enhancing GLUT1 expression. Conversely, low levels of let-7a-5p in triple-negative breast cancer (TNBC) correlate negatively with GLUT12 and promote the proliferation, migration, and invasion of TNBC cells (81, 82). More examples of different miRNAs and their role in various types of cancer are summarized in Table 1 .

Many lncRNAs exhibit tumor-related cell- or tissue-specific expressions, indicating their potential role as therapeutic targets. lncRNAs affect gene expression within the nucleus by regulating epigenetic and transcriptional mechanisms and in the cytoplasm by modifying post-transcriptional and translational processes (27, 83, 84). Like miRNAs, lncRNAs can function as oncogenes and tumor suppressors (85). For instance, overexpression of lncRNA HOTAIR has been implicated in the progression of various cancers (86, 87). Elevated HOTAIR levels can inhibit the activity of tumor suppressors such as protocadherin 10 (PCDH10), progesterone receptor (PGR), protocadherin β5 (PCDHB5), and junctional adhesion molecule 2 (JAM2), leading to tumorigenesis (39). It also has a distinguished role associated with immune evasion in the TME (88). H19, the first identified lncRNA overexpressed in HCC and rectal cancer, influences cancer development. H19 serves as a precursor for miR-675, and its elevated expression correlates with an upsurge in miR-675 levels, contributing to rectal cancer progression (89–91). lncRNAs can also function as tumor suppressors. TERRA, categorized as telomeric repeat-containing RNAs, are a group of lncRNAs transcribed from telomeres that may negatively regulate telomerase activity, thereby acting as tumor suppressors (39). MEG3 exhibits downregulation in cancer cells. In bladder cancer, the overexpression of MEG3 induces autophagy and contributes to p53 accumulation (92). LINC01089, for instance, is an oncogenic lncRNA that functions in liver cancer by stimulating the invasion of cancerous cells by its effects on the ERK/Elk1/Snail axis involved in the signaling pathway. LINC01089 is found to be a super-enhancer lncRNA consisting of a set of enhancers with many transcription factors that stimulate the transcription of oncogenic genes. Hence, targeting the super-enhancer can be a very promising, novel, and successful approach to cancer treatment (93).

lncRNAs interact with RBPs to regulate target genes, which can have a significant impact on AS (H. Huang et al., 2021). For instance, esophageal squamous cell carcinoma (ESCC) is associated with a poor prognosis when the lncRNA DGCR5 is highly expressed. In vitro, DGCR5 silencing decreases ESCC cell migration, invasion, and proliferation (94). AS is frequently associated with transcription processes in terms of transcriptional regulation, and lncRNAs can also affect AS through this mechanism (27, 71, 95). As an example, the lncRNA PVT1b inhibits the transcriptional activity of c-Myc, which reduces the proliferation of lung and pancreatic cancer cells (96–98). The expression of heterogeneous nuclear ribonucleoprotein (hnRNP) proteins, which dysregulate pyruvate kinase mRNA splicing in cancer, is known to be facilitated by the oncogenic transcription factor c-Myc (99–101). Additionally, HCC is affected by the oncogenic effects of the upregulated lncRNA MALAT1 (102). Through the Wnt pathway and c-Myc axis, MALAT1 transcriptionally activates the oncogenic splicing factor SRSF1. MALAT1 can modulate B-MYB AS and aid in the progression of the cell cycle by acting as a splicing factor decoy (71, 103).

While most lncRNAs are thought to be non-coding, some lncRNAs have been found to have translational effects and encode short peptides in certain situations (71). For instance, the conserved 53-amino acid peptide produced by the lncRNA HOXB-AS3 is associated with a poor prognosis in patients with CRC. The RNA-binding protein hnRNPA1 and the CRC growth are both inhibited by the HOXB-AS3 peptide, which also modifies the AS of pyruvate kinase M (PKM). Due to this modulation, the PKM2 isoform is formed less frequently, which ultimately helps suppress the growth of CRC (104–106). Additionally, it has been demonstrated that lncRNA LOC90024, which encodes the small peptide Splicing Regulatory Small Protein (SRSP), promotes the development and metastasis of CRC. To affect AS, SRSP interacts with several splicing regulators, including SRSF3. SRSP increases SRSF3’s binding to exon 3 of the transcription factor Sp4, which results in the production of the oncogenic isoform Sp4-L and the inhibition of the non-oncogenic isoform Sp4-S (107–111). Another example is the nuclear lncRNA CCAT 1, which interacts with the CCCTC-binding transcription factor (CTCF) to function as an oncogene and control the intra-chromosomal interactions of known oncoproteins like c-MYC, thereby promoting CRC tumorigenesis (27, 112). More examples of different lncRNAs and their role in various types of cancer are summarized in Table 1 .

circRNA can influence glucose metabolism by modulating some key enzymes (81). For instance, To prevent cell apoptosis, circ-Amotl1 translocates to the nucleus and interacts with PDK1 and AKT1 (113–115). Cichipk3 can sponge miR-124, which then inhibits the expression of several transporters and glycolytic enzymes (115, 116). Moreover, circRNF13 is essential for the programming of nasopharyngeal carcinoma (NPC) glucose metabolism because it stabilizes SUMO2 mRNA, which increases GLUT1 ubiquitination and SUMO degradation (81, 117). In CRC, the upregulation of lncRNA GAL promotes liver metastasis. GAL interacts with GLUT1 to improve SUMOylation, which increases GLUT1 mRNA stability (81, 118). Furthermore, by sponging miR-760, circDENND4C increases GLUT1 expression, which increases the growth of CRC (119–121). m6A modification of circFOXK2 increases GLUT1 stability, which subsequently plays a carcinogenic role in oral squamous cell carcinoma (OSCC) (122). Furthermore, circRNAs affect lipid metabolism. Abnormalities in lipid metabolism can influence cancer development, with increased lipolysis contributing to cancer cachexia, a syndrome characterized by significant fat loss (123–126). For example, circ-0046367 binds to miR-34a, protecting peroxisome proliferator-activated receptor (PPAR)α from transcriptional repression. Lipid degradation is stimulated through activation of CPT2 and ACBD3 by PPARα (39).

circRNA regulates metabolism, but it can also affect transcription, mRNA splicing, protein localization, and activity through interactions with RNA polymerase II and small nuclear RNA (snRNA) (37, 127). Higher expression levels of circRNA FBXW7 correlate with lower patient survival rates compared to those with lower expression, and the FBXW7-185AA protein, encoded by glioblastoma circRNA FBXW7, plays a critical role in glioblastoma formation and prognosis, its expression is reduced in glial tissue (39, 128). The functional protein SHPRH-146aa, which is encoded by circ-SHPRH, functions as a tumor suppressor in glioblastoma and is expressed at a reduced level in this type of cancer (129, 130). Additionally, circURI1 functions as a tumor suppressor, while circRNA_0000285, circRNA WHSC1, and hsa_circ_001783 are recognized as oncogenes (39).

Through a variety of mechanisms, such as functioning as miRNA sponges, interacting with RBPs, controlling transcription, and acting as translation templates, circRNAs play crucial roles in tumorigenesis (71). One AS modulator implicated in the development and metastasis of cancer is circURI1. circRNA profiling of five paired gastric cancer (GC) and nearby non-cancerous tissue specimens revealed the presence of circURI1. circURI1 promotes GC metastasis in vitro and in vivo and shows higher expression levels in GC compared to para-cancerous tissues (131, 132). Their function as miRNA sponges or competing endogenous RNAs (ceRNAs) is one common way that circRNAs function. circRNAs may be linked to AS when their targets are SFs (133–135). By altering the expression of epithelial splicing regulatory protein 1 (ESRP1) through the miR-526b-5p/c-Myc/TGF-β1 pathway, circUHRF1 promotes OSCC (136–138). CiRS-7, which acts as a sponge for miR-7, contributes to the advancement of various malignancies, including CRC, via interacting with the MAPK and PI3K pathways (139, 140). circ-LRIG3 is another circRNA that helps promote metastasis in HCC by upregulating the MAPK pathway (141). More examples of different circRNAs and their role in different types of cancer are summarized in Table 1 .

miRNAs influence inflammation from initiation to resolution through positive and negative feedback. Positive feedback aids in pathogen defense and tissue repair, while negative feedback maintains tissue homeostasis during severe inflammation (147). An example would be miR-155, a miRNA derived from the ncRNA transcript of the B cell integration cluster (BIC) protooncogene (148). miR-155 is conserved in humans and mice (149). It is induced by transcription factors such as AP-1, MYB, PU.1, STAT3, and Ets2, particularly through AP-1 during toll-like receptor (TLR) agonist activation. It targets several inflammatory mediators, including TNF-α and interferons. In contrast, the anti-inflammatory cytokine IL-10 downregulates miR-155 by suppressing TLR4 signaling and inhibiting Ets2 transcription in a STAT3-dependent manner in response to lipopolysaccharide (LPS). miR-155 is highly expressed in various innate and adaptive immune cells, including monocytes and macrophages. It promotes macrophage proliferation and pro-inflammatory cytokine secretion (IL-6 and TNF-α) by targeting SHIP1 and SOCS1. Additionally, SOCS1, a target of miR-155, negatively regulates M1 macrophage polarization by inhibiting the JAK2/STAT1 pathway and TLR/NF-κB signaling. SOCS1, targeted by miR-155, inhibits M1 macrophage polarization by suppressing the JAK2/STAT1 and TLR/NF-κB pathways (150, 151). Evidence shows that miR-155-3p is also active in regulating different genes. miR-155 has confirmed targets that can induce both pro- and anti-inflammatory responses, including negative regulators like SOCS1 and SHIP-1, which, when suppressed, promote inflammation (152). Notably, miR-155 can have anti-inflammatory effects as well; for example, it targets PI3Kγ to suppress mast cell activation. In LPS-activated macrophages, miR-155 inhibits TLR signaling by targeting IRAK1 and TRAF, creating a negative feedback loop that reduces macrophage activation. However, overexpression of miR-155 can paradoxically increase LPS-induced TNF production in both in vitro and in vivo settings (153). Systemic lupus erythematosus (SLE) is an autoimmune disorder with reduced and impaired regulatory T cells (Tregs) and is associated with higher cancer rates and mortality (154). A study was conducted to investigate the role of miR-155 and SOCS1 in Treg function and stability in SLE. SLE patient and SLE-induced mouse Tregs showed decreased SOCS1 and increased miR-155 levels. Inflammatory cytokine-stimulated Tregs required NF-κB signaling for altering SOCS1 and miR-155 expression. miR-155 negatively regulates SOCS1, diminishing Treg function and differentiation. Conversely, inhibiting miR-155 enhances Treg function and improves SLE conditions in mice. Inflammation-driven miR-155 compromises Treg stability by lowering SOCS1, suggesting that targeting miR-155 could be a potential SLE treatment (155).

Unlike miR-155, some miRNAs have a dual role in inflammatory response. This includes miR-21, which acts both as a pro-inflammatory agent and as an inhibitor of inflammation. It is associated with various illnesses, particularly malignancies, and functions as a key regulator of inflammatory processes. Studies show miR-21 is upregulated in asthmatic children and experimental asthma models while downregulated in cord blood monocytes from children with allergic rhinitis, linking it to airway inflammatory diseases. Increased miR-21 levels are linked to conditions like asthma and lumbar spinal canal stenosis, which promotes inflammation (156). In addition to that, alterations in the expression of miR-21-5p downregulate TLR/NF-κB signaling by reducing TRAF6 and PDCD4 levels, leading to decreased proinflammatory cytokines in certain types of cells such as human dental pulp cells (hDPCs) (157). Evidence shows that miR-21-5p is crucial in TGF-b1 signaling in keratinocytes (KCs). TGF-b1 increases miR-21-5p expression via transcriptional and post-transcriptional mechanisms involving SMADs and RNA helicase p68. Overexpression of miR-21-5p boosts KC proliferation and migration by targeting PTEN, PDCD4, and TIMP3 while inhibiting the G1-to-S phase transition through CDC25A downregulation and CDK2 activation. Additionally, miR-21-5p is linked to skin inflammation, being highly expressed in psoriatic lesions, where its upregulation affects the IL-6/STAT3 pathway and activates TACE/ADAM17. IL-22 also induces miR-21-5p, which, alongside miR-21-3p, promotes KC proliferation via cyclin D1 upregulation (158). In addition to miR-21-5p, miR-31 potentially induces wound edge keratinocytes and is regulated by NF-κB and STAT3 during inflammation. Using miR-31 loss-of-function mouse models, a study by Shi et al., 2018, demonstrated that miR-31 enhances keratinocyte proliferation and migration by activating the Ras/MAPK pathway by targeting negative regulators Rasa1, Spred1, Spred2, and Spry4 (159).

Furthermore, some miRNAs regulate inflammation, hematopoiesis, allergic responses, and aspects of the innate immune system. For example, miRNA-146a is a single-stranded ncRNA that serves as a diagnostic and prognostic biomarker for various diseases. Polymorphisms in miRNA-146a can influence the development of autoimmune disorders and cancer. It affects gene expression by controlling proteins like IRAK1, IRAK2, and TNF receptor 6 and modulates pathways such as TNF, NF-κB, MEK-1/2, and JNK-1/2. Research shows that miRNA-146a’s role in stem cell synthesis contributes to tumorigenesis (160). miRNA-146a targets IRAK1 and TRAF6, proteins involved in TLR and IL-1 receptor signaling, to inhibit proinflammatory mediator secretion and block TLR signals. miRNA-146a is crucial for endotoxin-induced tolerance, reducing monocyte responsiveness to LPS after repeated exposure and preventing inflammation. LPS exposure raises miRNA-146a levels in THP-1 cells, negatively correlating with TNF levels, indicating LPS tolerance (161). Positive regulation of miRNA-146a is essential for tolerance activation; its transfection induces tolerance without LPS priming, while its knockdown diminishes LPS tolerance (162). miRNA-146a is a key negative feedback regulator in vertebrate innate immunity, primarily targeting components of the MyD88-dependent signaling pathway, reducing inflammatory mediator synthesis. While research has mainly centered on the TLR pathway and inflammatory cells, miRNA-146a is also expressed in various cell types and may have other functions depending on the context (160, 163).

miR-122 plays a role in immune response and enhances p65-mediated NF-κB signaling by targeting IκBα. The NF-κB p65 subunit’s NLS interacts with IκBα’s ANK1, while the p50 subunit’s NLS connects with IκBα’s ANK2, forming a trimer that sequesters NF-κB in the cytoplasm (164). A study was conducted on endothelial progenitor cells (EPC cells) co-transfected with NF-κB, IL-1β or IL-8 reporters, and IκBα shows that the overexpression of p65-activated these reporters, whereas IκBα inhibits this activation. miR-122 down-regulates IκBα, promoting the activation of NF-κB, IL-1β, and IL-8 reporters. Luciferase assays confirmed that miR-122 facilitates this activation, and its inhibitor reversed miR-122’s effects. This suggests that miR-122 exerts an inhibitory effect on the levels of IκBα mRNA and may facilitate the degradation of IκBα mRNA. This indicates that miR-122 plays a regulatory role in modulating IκBα and, consequently, the innate immune response (165).

miR-26a expression was reported to rapidly decrease after TLR4 stimulation in microglia. Overexpression of miR-26a significantly lowered inflammatory cytokines like TNF-α and IL-6, while its knockdown increased their production. miR-26a negatively regulates LPS-induced cytokine production in microglia, partly by targeting ATF2 (166). Furthermore, a previous study indicates that miR-26a overexpression disrupts PI3K signaling, which is a pathway involved with cancer and therapy, primarily targeting PTEN to impede early B cell development (167). An inverse relationship between miR-26 levels and IL-6 has been observed in some tumor cells, suggesting that miR-26 may regulate inflammation and tumorigenicity by down-regulating IL-6. IL-6, a multifunctional cytokine, plays significant roles in chronic inflammatory diseases and promotes tumor cell proliferation, survival, angiogenesis, and immune tolerance (168). Previous studies indicate that miR-124 regulates microglial polarization, promoting the transition from pro-inflammatory M1 to anti-inflammatory M2. It reduces inflammation by downregulating TNF-α, major histocompatibility complex II, and reactive oxygen species. Furthermore, miR-124 is a key regulator of microglial quiescence in the central nervous system (CNS) and a novel modulator of monocyte and macrophage activation (169).

lncRNAs are major players in the inflammatory pathway as they have crucial roles in not only expression but also differentiation of cytokines and immune cells, respectively (170). The transcription of inflammatory genes is influenced by lncRNAs, which are important regulators of the inflammatory response. Their functions include enhancing or suppressing inflammatory transcription, modulating gene-specific, time-dependent epigenetic control of inflammatory transcription, and acting as scaffolds for RNA-binding proteins in chromatin remodeling (171). TLR2 activation triggers the production of several lncRNAs, such as THRIL (TNFα- and hnRNPL-related immunoregulatory lncRNA), which can induce inflammatory responses through signals such as NF-κB signaling (172). THRIL knockdown decreases TNF-α secretion in unstimulated cells and following TLR2 activation. Through its interaction with hnRNPL, THRIL acts as a scaffold, forming a complex that binds to the TNF-α promoter to increase transcription. PACER is upregulated and controls the expression of the neighboring inflammatory gene PTGS2 (COX-2) after stimulation by LPS, IL-1β, or TNF-α (171, 173, 174). Furthermore, MALAT1 influences T-cell function, with naïve T-cell activation leading to reduced expression (175). The conserved protein MALAT1 is expressed in septic rat hearts, cardiac microvascular endothelial cells, and LPS-activated macrophages. It is also linked to several human cancers and immune responses, especially acute inflammation (176, 177).

By modifying several immune genes, lincRNA-Cox2, a lncRNA that is located next to the Ptgs2 (Cox2) gene, is also known to be an essential regulator of inflammatory responses. Like Ptgs2 induction via the MyD88 and NF-κB pathways, LPS stimulation increases lincRNA-Cox2 expression in dendritic cells and bone marrow-derived macrophages (BMDM). In BMDM, lincRNA-Cox2 overexpression or silencing affects important immune genes such as TNFα, IL-6, CCL5, SOCS3, and STAT3. Among the mechanisms of action are cytosolic IKB-α degradation, binding with hnRNP A/B and A2/B1, participation in the SWI/SNF complex, increasing NF-κB activity, and chromatin remodeling. It was recently demonstrated that lincRNA-Cox2 increases the transcription of TNFα-induced IL-12b by attracting the Mi-2/NuRD repressor complex to its promoter. Overall, acute inflammatory signaling is significantly influenced by lincRNA-Cox2 activation (178–182). Another example is lincRNA-p21, which was first discovered to be a repressor of p53-dependent transcription. The expression of many p53-repressed genes changed when lincRNA-p21 was silenced; these changes could be undone by blocking p53, suggesting that lincRNA-p21 functions as a downstream repressor of p53. Interaction with hnRNP-K is a part of this repression mechanism. The positive correlation between p53 levels and lincRNA-p21 expression in rheumatoid arthritis (RA) patients raises the possibility that basal lincRNA-p21 levels in peripheral blood mononuclear cells (PBMCs) are p53-independent (180, 183).

lncRNA HOTAIR is crucial for cytokine regulation and inflammation in macrophages. During LPS-induced inflammation, HOTAIR is upregulated in macrophages, where it controls NF-κB activation by influencing IκBα degradation. This affects the expression of pro-inflammatory and cytokine genes, such as IL-6 and iNOS. GLUT1 is expressed in macrophages in response to LPS, and it was found that HOTAIR controls this expression, affecting glucose uptake and metabolism, which is essential for the cells’ energy during inflammation. As a result, HOTAIR is essential for controlling the inflammatory response and macrophage glucose metabolism (184, 185). RA patients’ PBMCs and serum exosomes exhibit higher HOTAIR expression, whereas differentiated osteoclasts and rheumatoid synoviocytes exhibit lower HOTAIR expression. Through the regulation of miR-138, lentiviral overexpression of HOTAIR decreased the levels of IL-17, IL-23, IL-1β, and TNFα and prevented NF-κB activation in chondrocytes treated with LPS (180, 186, 187). On the other hand, HOTAIR expression in cardiomyocytes dramatically rose in a mouse model of sepsis. In addition to lowering TNFα synthesis and p65 phosphorylation in cardiomyocytes, silencing HOTAIR enhanced cardiac function in septic mice (180, 188).

Adenovirus-mediated overexpression of liver-expressed lncRNA (LeXis) in the liver, using a thyroxine-binding globulin promoter, reduced aortic lesion size and total serum cholesterol levels, confirming its role in maintaining hepatic sterol content (180). Another lncRNA is RP5-833A20.1, which reduces cholesterol efflux and increases inflammatory cytokines, including IL-1β, IL-6, and TNFα in THP-1 macrophages. Mechanistically, RP5-833A20.1 decreases the expression of NFIA by inducing miR-382–5p expression (189). Moreover, NEAT1-/- mice reveal NEAT1 as a novel lncRNA immunoregulator influencing monocyte-macrophage functions and T-cell differentiation. It is involved in a deregulated molecular circuit with various chemokines and interleukins post-MI, which could help identify high-risk patients for immunomodulatory therapies (190). Another example is ANRIL, whose silencing led to an elevation in the expression levels of the antisense transcripts p15ARF and p16INK4b, which are crucial regulators of senescence, apoptosis, and self-renewal of stem cells through the retinoblastoma-p53 pathway by disrupting PRC-1/2 attachment to their respective loci. Additionally, ANRIL directly binds to PRC-1/2 components like SUZ12 and CBX7, highlighting its function in epigenetic regulation. Contradictory results may result from isoform-specific effects caused by its multiple splice sites (180, 191).

Additionally, lncRNAs have the feature of acting as a sponge for miRNAs, masking their binding to their target mRNAs and therefore influencing gene expression and may regulate miRNAs as competitive endogenous RNAs (ceRNAs), contributing to autoimmune diseases (192–194). For instance, lncRNA HIX003209 enhances macrophage-mediated inflammation via TLR2/TLR4 and thereby contributes to the pathogenesis of RA. Through the IκBα/NF-κB signaling pathway, it stimulates the activation and proliferation of macrophages. By binding to miR-6089, lncRNA HIX003209 functions as a competing endogenous RNA (ceRNA), reviving TLR4 expression and stimulating NF-κB in macrophages (194). lincRNA-cox2 governs the release of pro-inflammatory cytokines TNF-α and IFN-γ, which have a significant impact on immune response (170).

circRNAs play a role in inflammation and cancer by modulating cellular components and influencing cancer-related inflammatory signaling pathways, often acting as miRNA sponges to activate or repress these pathways (195–197). They may function by binding to cRBPs and by encoding translatable peptides that modulate disease-related signaling pathways. They also interact with the PI3K/AKT pathway primarily through competing endogenous RNAs that sponge miRNAs, activating or repressing downstream pathways (196, 198). circHIPK3 was found to increase Foxo3a expression, functioning as a miR-421 sponge to inhibit inflammation and prevent ischemic injury (199). circHIPK3 expression was upregulated in synovial fluid mononuclear cells (SFMCs) from gouty arthritis patients. It enhances TLR4 expression and the NLRP3 inflammasome by sponging miRNAs, thus promoting inflammation in gouty arthritis (200). Pro-inflammatory cytokines are released into the TME and IME by NLRP3 inflammasomes, which NF-κB activates. This promotes the pathogenesis of inflammatory diseases and signaling pathways linked to cancer. Tumor and immune cells affect the initiation and spread of cancer, making the TME more difficult by facilitating metastasis, proliferation, and evasion. While TAMs, TANs, CAFs, MDSCs, and Tregs contribute to immunosuppression, T lymphocytes, B lymphocytes, natural killer, and dendritic cells are essential for tumor suppression (196).

Circular ANRIL (cANRIL), which is produced by exon skipping, disrupts pre-rRNA processing and ribosome biogenesis in SMCs and macrophages by binding to PES1, a crucial component of 60S preribosomal assembly. Like linear ANRIL, this causes nucleolar stress and p53 activation, which inhibits proliferation and promotes apoptosis (201, 202). Additionally, circ_0001005 and Exo-circGSE1 are prominent instances of interacting with the TME, encouraging immune system escape by altering immunity checkpoints such as PD-L1 (203). More examples of miRNAs, lncRNAs, circRNAs, and their role in inflammation are summarized in Table 2 .

In recent years, there have been tremendous advancements in ncRNA therapies, with several potential candidates progressing through clinical trials and even gaining regulatory approval. To date, 11 RNA-based therapeutics in the form of either antisense oligonucleotides (ASOs) or small interfering RNAs (siRNAs) have been approved by the FDA and/or the European Medicines Agency (EMA) (204). The RNA therapeutics targeted diseases include hereditary transthyretin amyloidosis, primary hyperoxaluria type 1, and Duchenne muscular dystrophy, and most of these therapies are delivered subcutaneously (targeting the liver). In contrast, the minority are delivered intravenously (targeting the liver or muscle) ( Table 3 ). Despite currently having only ASOs and siRNAs on the market, multiple novel RNA therapeutics, such as miRNA mimics and anti-miRNAs, are in clinical development phase II or III clinical development ( Table 3 ). At the same time, several other RNA-based therapies are being researched, such as therapeutic circRNAs, miRNA sponges, short hairpin RNAs (shRNAs) and CRISPR-Cas9-based gene editing (205–207). The use of miRNA therapies has multiple potential advantages over the currently approved ASO and siRNAs. Because miRNAs target a plethora of genes by nature, their effect is multifactorial while being specific in the case of targeting multiple genes in the same pathway. A good example of this is miR-21 which has been shown to target multiple genes in the PI3K-Akt pathway, such as PTEN and PIK3R1 (74, 208). This powerful effect of targeting multiple downstream genes presents a huge potential in boosting therapeutic effects; however, it does not come without drawbacks, as multiple targets also lead to off-target effects, which brings us to the problem of biological and technical challenges faced by ncRNA therapies research and development.

Because of the presence and stability of ncRNA biomarkers in body fluids such as blood, urine, or saliva, they began to revolutionize clinical applications for early disease detection, including cancer and inflammatory diseases. Previous research reported that the expression of peripheral lncRNA MALAT1 was measured in patients with NSCLC and healthy subjects. MALAT1 was upregulated in NSCLC patients, providing a foundation for the possibility of MALAT1 as a biomarker assisting in distinguishing this disease at early stages. Moreover, the combination of MALAT1 and other established markers, such as carcinoembryonic antigen (CEA), could play a valuable role in enhancing the diagnostic performance of either marker. Additionally, lncRNAs such as SPRY4-IT1, ANRIL, and NEAT have high accuracy in detecting NSCLC (235, 236).

Different expression levels of ncRNAs, especially miRNAs, in inflammatory diseases indicate the progression of such diseases, including inflammatory bowel disease and RA (147). Researchers investigated the role of HOTAIR in inflammation regulation within macrophages. When NF-κB was suppressed, several long non-coding inflammation-associated RNAs (linfRNAs), including HOTAIR, decreased. HOTAIR was shown to alleviate RA symptoms by targeting miR-138, inhibiting inflammation pathways (237). This suggests that ncRNAs like HOTAIR could be used as non-invasive tests for early detection of inflammatory diseases (184). The knockdown of linfRNA1 also reduced cytokine levels, further indicating its potential as a biomarker for diagnosing inflammatory conditions (237). In another context, researchers explored ncRNAs for their predictive value and role in the early detection of preeclampsia during pregnancy. A study identified certain circulating small ncRNAs expressed differentially between women who developed preeclampsia and those with normal pregnancies, highlighting their potential for early diagnosis (238).

Emerging diagnostic technologies like liquid biopsy highlight ncRNAs’ role in early cancer detection. Liquid biopsy analyzes circulating tumor DNA and ncRNAs from a simple blood draw, minimizing the need for invasive procedures. Circulating ncRNAs can distinguish between cancerous and non-cancerous cases with high sensitivity (238). Single-cell RNA sequencing (scRNA-seq) also detects gene expression at the single-cell level, identifying unique ncRNA signatures associated with specific cancer subtypes or stages, aiding early cancer diagnosis (239). Studies also demonstrate the potential of circulating lncRNAs as non-invasive biomarkers for CRC. Specific lncRNAs, such as XLOC006844 and LOC152578, showed stable expression in blood plasma and achieved sensitivity and specificity rates of 80% and 84%, respectively, in CRC detection. These findings suggest that circulating ncRNAs can improve compliance rates for CRC screening compared to traditional methods like colonoscopy (240).

A comprehensive analysis involving multiple studies highlighted the diagnostic efficacy of circulating miRNAs for HCC. A panel comprising miR-122, miR-192, and miR-21 achieved good results distinguishing HCC from chronic hepatitis B and cirrhosis, demonstrating how integrating ncRNA biomarkers enhances diagnostic sensitivity beyond traditional methods (238, 241). Research on OSCC identified a six-lncRNA diagnostic risk model with remarkable specificity and sensitivity in differentiating OSCC samples from normal tissues, showcasing the potential of lncRNAs in predictive models for early cancer detection (239). Altered expressions of miR-181 and miR-652 were also associated with advanced GC stages, highlighting their diagnostic potential in distinguishing early and late-stage disease (242).

Recently, scientists have explored the potential of ncRNAs as biomarkers for cancer prognosis and therapy response. ncRNAs play key roles in tumor behavior and patient outcomes. A study identified a lncRNA signature predicting outcomes and recurrence in stage II CRC, outperforming conventional clinicopathological data like CEA levels or T Stage. This panel allowed personalized treatment and improved survival outcomes (243). A meta-analysis demonstrated the predictive power of lncRNA signatures integrated with clinical risk factors, such as breast cancer. For instance, low levels of miR-206 were associated with poor overall survival and tumor progression, while overexpression of miR-1225 was linked to unfavorable prognostic markers, indicating their use in disease progression monitoring (244).

Novel miRNAs, such as MSM2 and MSM3, show promise as therapeutic targets due to their roles in cancer cell proliferation and migration. These miRNAs may also serve as prognostic indicators for cancer progression (245). Changes in lncRNA expression profiles can predict disease activity flares, enabling timely treatment adjustments (237). Dysregulated lncRNAs in SLE correlate with disease severity and clinical parameters like the erythrocyte sedimentation rate and autoantibody levels, aiding in disease monitoring (246). ncRNAs also contribute to the pathogenesis of multiple sclerosis, where specific miRNA profiles indicate disease activity and relapse rates, allowing real-time monitoring (247). Similarly, miRNA expression changes in Sjögren’s syndrome are linked to disease activity and response to therapies like interferon-beta, reinforcing their role in monitoring autoimmune diseases (248).

A lncRNA-based signature stratified CRC patients into high- and low-risk groups for recurrence-free survival, validating the model’s predictive accuracy (243). Another study found miR-93 effective as a prognostic biomarker for breast cancer, offering high sensitivity and specificity for non-invasive disease monitoring (244). In lung cancer, specific miRNAs like miR-21 are linked to poor prognosis in NSCLC, demonstrating their dual role in diagnosis and treatment prediction (249). A meta-analysis confirmed the prognostic value of ncRNAs for breast cancer, noting that high miRNA expression levels often correlate with poor survival and increased metastasis risks, particularly with elevated PVT1 levels (250). The lncRNA MALAT1, strongly associated with triple-negative tumor types in lung and breast cancer, also emerged as a significant predictor for disease-free and overall survival (251).

ncRNAs play a pivotal role in personalized medicine due to their biomarker and therapeutic target roles. Integrating ncRNA profiling into personalized medicine represents a transformative healthcare approach. Clinicians can tailor therapeutic strategies using ncRNA expression patterns, which are more effective than traditional modalities (252). For instance, circulating miR-139-5p correlates with improved survival rates in radiotherapy patients, enabling personalized treatment monitoring (253). Therapeutic approaches targeting ncRNAs, such as miRNA mimics or inhibitors, restore normal gene expression patterns disrupted in diseases. In lung cancer, anti-miR-155 therapy resensitized cancer cells to chemotherapy, highlighting how an individual’s ncRNA profile can guide personalized treatment strategies (207). Clinical trials incorporating ncRNA profiling have also shown promise. For example, a trial investigating miR-34a mimics with standard chemotherapy in lung cancer demonstrated that patients with specific miRNA expression profiles responded better, underscoring ncRNA’s potential in personalized approaches (254).

Chemoresistance remains a significant challenge, but developing miRNAs to counter resistance shows promise. For instance, miR-451a regulates chemotherapy resistance in gallbladder tumors (255). Also, HOTAIR predicts responses to neoadjuvant chemotherapy in breast cancer, where high expression levels are associated with poorer prognosis and treatment resistance. This highlights HOTAIR’s potential as a predictive biomarker for chemotherapy efficacy (250). Another example is lncARSR. Elevated lncARSR levels, associated with sunitinib resistance in renal cell carcinoma, were linked to poor outcomes. Targeting lncARSR reversed resistance mechanisms and improved treatment efficacy, emphasizing ncRNA profiling’s clinical relevance (256). Innovative treatment modalities targeting ncRNAs, such as ASOs, are under development. ASOs selectively bind to target lncRNAs, preventing their pathological effects. Promising results have been seen with ASOs targeting lncRNAs in breast cancer progression, offering a new avenue for personalized treatments (207, 252).

Several promising directions could play pivotal roles in ncRNA therapy efficacy and advancement. The rapid expansion of the bioinformatics field, along with its genomic technologies, immensely helps in ncRNA research and enables scientists to understand the roles of ncRNAs. Of these advances, high-throughput sequencing is at the top of the list in identifying promising ncRNA candidates that could either serve as therapeutic targets or biomarkers. The advancement and accessibility of such screening methods also benefit the field of precision or personalized medicine. The recent advances in gene sequencing and gene editing enable the design of effective patient-specific cell therapies, and this trend has pushed for the development of treatment that would overcome the standard approaches. This trend pushed for the development of a treatment that would overcome the standard approaches and, as a result, improve therapy outcomes in clinical settings (288, 289). In cancer medicine, the stratification of patients through the biomarkers they exhibit, as well as diagnostics that accompany the patient profile, has become the standard for anti-cancer drug development. Soon, the study of nanoparticles will employ the same standard of stratification of the patient population to develop effective personalized medicine (290). The heterogeneity of many diseases, notably in cancer, is challenging in the development of a one-size-fits-all ncRNA therapy since the expression of ncRNAs, as well as their function, varies significantly due to genetic variabilities among patients. This heterogeneity means that a single ncRNA therapy for a certain disease may not be applicable or efficient across the broad population, and genomic profiling and bioinformatic tools will provide a much more accurate identification of the potential of a specific ncRNA being effective on a certain patient or not. Not only this, but also a screening of patient tumors for ncRNA is helping enable the identification of ncRNA signatures associated with certain diseases, and this helps in the establishment of novel biomarkers (291).

CRISPR-Cas9 offers a whole array of exciting possibilities in ncRNA research. It could allow for the precise targeting of ncRNA regulatory elements within ncRNAs, such as promoters of lncRNAs, or by modulating the expression levels of non-coding RNAs. However, in a study targeting lncRNAs in glioma cells, CRISPR interference (CRISPRi) was used to knock down thousands of lncRNAs and test the effect on radiation therapy sensitivity of glioma cells. The results were impressive, and a single lncRNA was identified that was found to significantly sensitize glioma cells to the treatment. Thus, a single lncRNA was identified and found to significantly sensitize glioma cells to the treatment. Thus this study demonstrated the potential of CRISPRi as a promising tool for identifying novel therapeutic targets (292). For the CRISPR–Cas9 system to be applied physiologically however, delivery challenges, especially regarding the immune response to the Cas9 proteins, must be carefully studied and overcome (207, 293). Finally, there is much promise in investigating combination therapies that incorporate ncRNA interventions with currently used treatments like immunotherapy or chemotherapy. In cancer and other complicated diseases, these combination approaches may improve therapeutic efficacy and reduce resistance mechanisms that frequently hinder treatment outcomes. Patient outcomes may be enhanced by sensitizing tumors to traditional treatments through the use of ncRNAs (294, 295). Much effort is also being exerted towards the creation of nanoparticles that can co-deliver various therapeutic compounds to target multiple genes in numerous cells: polymeric micelles and circulating nanoparticles with a pH-regulated drug release mechanism have demonstrated good initial results in preclinical studies (296, 297). Another promising approach is the development of bio-engineered lncRNA molecules capable of carrying multiple small RNAs at once, including siRNAs, antimiRs, and miRNA mimics. These constructs have shown a successful inhibition in the growth of multiple cancer cell lines in vitro and will probably be further explored in other contexts (298).