Head and neck carcinoma (HNC) is a prevalent category of cancers, primarily consisting of squamous cell carcinomas, which account for over 90% of malignant cases (1, 2). A significant majority of patients, approximately 70%, are diagnosed with intermediate to advanced stages, resulting in an unsatisfactory 5-year survival rate of less than half (1, 3, 4). Regrettably, the prognosis for HNC has not shown notable improvement in recent years, largely attributed to the constraints imposed by the available treatment modalities (5). The issue of resistance to primary treatments for HNC, including chemotherapy (e.g. cisplatin) and immunotherapy, constitutes a significant determinant of prognosis (6, 7). In light of the groundbreaking therapeutic advancements facilitated by immune checkpoint antibodies and other therapies reliant on protein-protein interactions (PPIs), it is noteworthy that only a minority of patients with HNC exhibit positive responses (8–10). This phenomenon can potentially be attributed to the abnormal expression of certain proteins in tumor cells, which consequently impairs immune cell functionality, leading to tumor immune evasion and immunosuppression (11–14). Noteworthily, the investigation of eukaryotic initiation factor 3c (eIF3C) as a potential antitumor target in the therapeutic exploration of HNC has been progressively undertaken (15, 16). eIF3C, a constituent of the largest eukaryotic translation initiation factor eIF3 complex, plays a crucial role in regulating transcript-specific translation during development and exhibits elevated expression levels in various cancer types (15, 17, 18). Suppression of eIF3C results in disruption of translation initiation complexes and decreased protein expressions, leading to cell cycle arrest and apoptosis (15, 16, 19). Nevertheless, similar to other tumor-specific proteins and associated PPIs, inhibiting eIF3C through direct protein-level regulation poses significant challenges.

In the past few years, there has been a rise in cancer therapeutic approaches that focus on addressing aberrant target protein levels in tumor cells (20–22). Among these approaches, small interfering RNAs (siRNAs) have shown potential in rectifying the expression of specific genes, thereby offering a promising avenue for tumor therapy (23–26). Unlike peptides and protein-based drugs, which possess intricate interfaces connecting multiple protein structural features, siRNAs directly suppress targets on the pre-expression level, thereby impeding the development of tumor-promoting PPIs (27, 28). Moreover, the therapeutic strategies involving siRNA exhibit the capability to reach intracellular targets, a feat that proves challenging for drugs based on PPIs (29). Therefore, it is promising to show beneficial effects in anti-tumor immunity by reducing the levels of proteins involved in immune escape through siRNAs. Nevertheless, siRNAs suffer from inadequate stabilization, susceptibility to degradation, absence of tumor targeting, and confront obstacles in terms of applicability (25, 26). Naked siRNAs, in particular, are subject to ineffective depletion due to endonuclease degradation, nonspecific uptake by macrophages, charge repulsion, and other physiological barriers, resulting in insufficient concentration at the tumor site (26, 30, 31). Consequently, there is a pressing necessity to devise a strategy for transforming therapeutic siRNAs into viable clinical drugs to address the treatment of HNC.

Herein, we present a comprehensive approach to transform flexible siRNAs into stable and biologically active infinite Auric-sulfhydryl coordination supramolecular siRNA (IacsRNA), using a mild and straightforward chemical pathway, building upon prior research (32, 33). By employing this methodology, we successfully converted eIF3C siRNAs into an HNC therapeutic agent, exhibiting anti-tumor efficacy both in cellular and animal models. Specifically, Iacs-eif3c-RNA precursors, prepared by the reaction of mercapto-modified eIF3C siRNA with gold, was binding with each other to assemble into carrier-free nano-particles driven by gold-thioether coordination, called Iacs-eif3c-RNA ( Figure 1 ). Through a xenograft murine model of head and neck squamous cell carcinoma (HNSCC), it is successfully demonstrated that Iacs-eif3c-RNA effectively overcame the pharmacological barrier associated with eIF3C, significantly reduced the expression level of eIF3C in tumor tissues and exhibited inhibitory effects on tumor growth in vivo. Furthermore, it is revealed that in HNSCC xenograft mouse models constructed with cisplatin-resistant cell line, Iacs-eif3c-RNA demonstrated superior anti-tumor efficacy and remarkable biosafety compared to cisplatin. This work provides a novel and effective carrier-free nucleic acid nanotherapeutic agent for the treatment of HNC, and proposes a promising approach for the translation of therapeutic siRNAs into potential clinical drugs for the management of cancer and other ailments.

The main reason for the poor prognosis of HNC may be due to its risk for relapse and drug resistance (38, 39). For example, the prevalence of drug resistance to cisplatin, a frequently employed chemotherapy agent in the clinical management, was observed to be common during HNC treatment, with a subset of patients exhibiting unresponsiveness to this drug (4, 40, 41). In the last decade, targeted therapeutic drugs with precise positioning and low toxicity provide a gaining interest and promising solution for the treatment of a variety of tumors, including HNC (42–44). Several targeted drugs, such as cetuximab and pembrolizumab, have showed excellent therapeutic potential in the treatment of HNC at present (45–47). As an important subunit of translation initiation factors, eIF3C is positively correlated with Hedgehog signaling pathway (17, 48), which participated in the immunoevasion of certain tumors (49, 50). eIF3C was also involved in the regulation of a variety of human cancers, such as ovarian cancer (18), lung adenocarcinoma (51), and renal cell carcinoma (52). For all the above reasons, eIF3C have been considered to be a promising therapeutic target for HNC (16). Utilizing eIF3C siRNA as a foundation, we have successfully designed and synthesized the targeted therapeutic agent Iacs-eif3c-RNA. ( Figures 2 , 3 ) In contrast to peptide and protein derived drugs that possess intricate structures and mechanisms, Iacs-eif3c-RNA exhibited a remarkable ability to suppress tumor growth in the HNC xenograft model by effectively downregulating the gene expression of eIF3C. ( Figure 5 ) The xenograft models constructed from cisplatin-resistant HSNCC cell lines exhibited notable weight reduction subsequent to cisplatin administration, indicating the associated systemic toxicity. Conversely, the utilization of Iacs-eif3c-RNA demonstrated an enhanced therapeutic outcome in terms of inhibiting tumor growth, while not inducing any obvious toxicity symptoms. ( Figure 6 ) This finding presents a novel and efficacious approach for HNC management.

As early as 2012, the proposal to develop siRNA-based drugs for HNC treating was put forth, which achieved significant anti-tumor effects (53–56). These siRNA drugs function by targeting specific genes, thereby disrupting the expression of target proteins in tumors, leading to cell apoptosis and the modification of the tumor microenvironment to achieve precise tumor suppression. Nevertheless, the clinical application of siRNA-based therapies necessitates considerations of biological activity, transfection efficiency, and biological safety (26). Naked siRNA, when administered intravenously, lacks protection and is susceptible to degradation by endonucleases (26, 30). Additionally, the non-specific uptake of macrophages within the reticuloendothelial system can lead to phagocytic damage to siRNA (26). Within the interstitium, various factors, including the extracellular matrix, charge repulsion between siRNA and the cell membrane, and physiological barriers such as tight junctions, hinder the penetration of siRNA into tumor tissues (31). In the event that siRNA fails to achieve early endosomal escape upon cellular entry, it undergoes acidification and degradation by lysosomes, ultimately resulting in exocytosis (57). In recent years, there has been a continuous effort to enhance the efficacy of siRNA as clinical drugs by improving and updating the methods for preparing siRNA-enveloped nano systems (25, 32, 33, 58, 59). In this study, we used simple reactants to obtain Iacs-eif3c-RNA through a mild preparation method, which ensured the biological activity and improved the stability of siRNA effectively. ( Figure 3 ) Encouragingly, our findings suggested that Iacs-eif3c-RNA successfully suppressed the expression of the target gene eif3c in vivo, leading to the tumor growth inhibition ( Figures 5 , 6 ). In addition, Iacs-eif3c-RNA demonstrated no detrimental effects in terms of body weight, blood indexes, and organ tissue sections, indicating its favorable biosafety and potential for clinical application. ( Figure 4 and Figure S2 ) In conclusion, the utilization of Iacs-eif3c-RNA offers a reliable approach for therapeutic agent development for HNC. Moreover, our study presents a straightforward, effective, and secure strategy for the clinical application of other siRNA molecules.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The animal study was approved by Medical Ethics Committee of Xi’an Jiaotong University. The study was conducted in accordance with the local legislation and institutional requirements.

HL: Data curation, Formal Analysis, Investigation, Methodology, Software, Visualization, Writing – original draft. YH: Conceptualization, Formal Analysis, Investigation, Methodology, Supervision, Validation, Visualization, Writing – review & editing. ZL: Supervision, Writing – review & editing. SH: Project administration, Supervision, Writing – review & editing. TL: Conceptualization, Funding acquisition, Methodology, Project administration, Supervision, Writing – review & editing. QZ: Conceptualization, Data curation, Project administration, Resources, Supervision, Validation, Writing – original draft.