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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Pharmacol.</journal-id>
<journal-title>Frontiers in Pharmacology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Pharmacol.</abbrev-journal-title>
<issn pub-type="epub">1663-9812</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="publisher-id">1238587</article-id>
<article-id pub-id-type="doi">10.3389/fphar.2023.1238587</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Pharmacology</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Design, synthesis and antitumour activity evaluation of novel dolutegravir derivatives</article-title>
<alt-title alt-title-type="left-running-head">Hou et al.</alt-title>
<alt-title alt-title-type="right-running-head">
<ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fphar.2023.1238587">10.3389/fphar.2023.1238587</ext-link>
</alt-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Hou</surname>
<given-names>Xi-Xi</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="fn" rid="fn1">
<sup>&#x2020;</sup>
</xref>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Mao</surname>
<given-names>Long-Fei</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="fn" rid="fn1">
<sup>&#x2020;</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1019907/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Guo</surname>
<given-names>Yajie</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1009035/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Lou</surname>
<given-names>Chaoxuan</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Wang</surname>
<given-names>Lan</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1094590/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Li</surname>
<given-names>Rui-Fang</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1817525/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Wang</surname>
<given-names>Huili</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Li</surname>
<given-names>San-Qiang</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
<uri xlink:href="https://loop.frontiersin.org/people/2185684/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Yang</surname>
<given-names>Jian-Xue</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
</contrib>
</contrib-group>
<aff id="aff1">
<sup>1</sup>
<institution>Department of Pharmacy</institution>, <institution>The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology</institution>, <addr-line>Luoyang</addr-line>, <country>China</country>
</aff>
<aff id="aff2">
<sup>2</sup>
<institution>College of Basic Medicine and Forensic Medicine</institution>, <institution>Henan University of Science and Technology</institution>, <addr-line>Luoyang</addr-line>, <country>China</country>
</aff>
<aff id="aff3">
<sup>3</sup>
<institution>Department of Emergency</institution>, <institution>The Eighth Affiliated Hospital</institution>, <institution>Sun Yat-Sen University</institution>, <addr-line>Shenzhen</addr-line>, <country>China</country>
</aff>
<aff id="aff4">
<sup>4</sup>
<institution>University of North Carolina Hospitals</institution>, <addr-line>Chapel Hill</addr-line>, <addr-line>NC</addr-line>, <country>United States</country>
</aff>
<author-notes>
<fn fn-type="edited-by">
<p>
<bold>Edited by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/25157/overview">Heike Wulff</ext-link>, University of California, Davis, United States</p>
</fn>
<fn fn-type="edited-by">
<p>
<bold>Reviewed by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/2349067/overview">Tao Shi</ext-link>, The Scripps Research Institute, United States</p>
<p>
<ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/1669050/overview">Belgin Sever</ext-link>, Anadolu University, T&#xfc;rkiye</p>
</fn>
<corresp id="c001">&#x2a;Correspondence: Huili Wang, <email>huili.be@gmail.com</email>; San-Qiang Li, <email>sanqiangli2001@163.com</email>; Jian-Xue Yang, <email>Docyix1969@126.com</email>
</corresp>
<fn fn-type="equal" id="fn1">
<label>
<sup>&#x2020;</sup>
</label>
<p>These authors have contributed equally to this work and share first authorship</p>
</fn>
</author-notes>
<pub-date pub-type="epub">
<day>07</day>
<month>08</month>
<year>2023</year>
</pub-date>
<pub-date pub-type="collection">
<year>2023</year>
</pub-date>
<volume>14</volume>
<elocation-id>1238587</elocation-id>
<history>
<date date-type="received">
<day>12</day>
<month>06</month>
<year>2023</year>
</date>
<date date-type="accepted">
<day>21</day>
<month>07</month>
<year>2023</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#xa9; 2023 Hou, Mao, Guo, Lou, Wang, Li, Wang, Li and Yang.</copyright-statement>
<copyright-year>2023</copyright-year>
<copyright-holder>Hou, Mao, Guo, Lou, Wang, Li, Wang, Li and Yang</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p>
</license>
</permissions>
<abstract>
<p>Based on the modification of the structure of dolutegravir, we introduced 1,2,3-triazole moieties with different substituted groups and obtained a lot of novel dolutegravir derivatives. The activity of A549 cells treated with the derivatives was examined, and most compounds showed good inhibitory effects. Among them, compounds <bold>4b</bold> and <bold>4g</bold> were the most effective, and inhibited the growth of A549 cells with IC<sub>50</sub> values of 8.72 &#xb1; 0.11&#xa0;&#x3bc;M and 12.97 &#xb1; 0.32&#xa0;&#x3bc;M, respectively. In addition, compound <bold>4g</bold> induced apoptosis and clonal suppression in A549 tumor cells. Compound <bold>4g</bold> also activated the LC3 signaling pathway to induce autophagy in tumor cells, and activated the &#x3b3;-H2AX signaling pathway to induce DNA damage in tumor cells.</p>
</abstract>
<kwd-group>
<kwd>dolutegravir</kwd>
<kwd>1,2,3-triazole</kwd>
<kwd>antitumor</kwd>
<kwd>autophagy</kwd>
<kwd>DNA damage</kwd>
</kwd-group>
<custom-meta-wrap>
<custom-meta>
<meta-name>section-at-acceptance</meta-name>
<meta-value>Pharmacology of Anti-Cancer Drugs</meta-value>
</custom-meta>
</custom-meta-wrap>
</article-meta>
</front>
<body>
<sec id="s1">
<title>1 Introduction</title>
<p>Dolutegravir (DTG, <xref ref-type="fig" rid="F1">Figure 1</xref>) is an HIV integrase inhibitor that blocks the strand transfer step of retroviral DNA integration by binding to the active site of the integrase. An <italic>in vitro</italic> experiment found that dolutegravir inhibited the strand transfer catalyzed by recombinant HIV-1 integrase with a half maximal inhibitory concentration (IC<sub>50</sub>) of 2.7&#xa0;nM(<xref ref-type="bibr" rid="B6">Johns et al., 2013</xref>; <xref ref-type="bibr" rid="B5">Jay et al., 2020</xref>; <xref ref-type="bibr" rid="B9">Manoj et al., 2020</xref>). Patients only take this drug once daily; among patients infected with HIV-1 for the firsttime, the therapeutic effect of dolutegravir is equivalent to that of raltegravir (RAL, <xref ref-type="fig" rid="F1">Figure 1</xref>), which is administered twice per day (<xref ref-type="bibr" rid="B4">Eron et al., 2013</xref>). Furthermore, dolutegravir possesses potent anti-resistance properties. Preclinical study results showed that dolutegravir had low toxicity and no genotoxicity or carcinogenic toxicity, and there was no apparent teratogenicity or reproductive toxicity when the dose was 27-fold greater than the clinical dose (<xref ref-type="bibr" rid="B2">Chen et al., 2018</xref>). Dolutegravir has been combined with other antiretroviral drugs, such as lamivudine or abacavir, to form highly active antiretroviral therapy (ART), which has been recommended by the WHO as the first-line treatment drug for all populations, including pregnant women and women of childbearing potential (<xref ref-type="bibr" rid="B3">Collins et al., 2021</xref>).</p>
<fig id="F1" position="float">
<label>FIGURE 1</label>
<caption>
<p>The structures of DTG and RAL.</p>
</caption>
<graphic xlink:href="fphar-14-1238587-g001.tif"/>
</fig>
<p>With the high therapeutic effect of ART, HIV-related opportunistic infections have been effectively controlled. However, with a prolonged disease course, patients are in a long-term immunosuppressive state, and malignant tumors have increasingly become the main cause of death in these patients. Some studies found that among young HIV-infected patients, the primary lung cancer incidence was more than six-fold that of the general population (<xref ref-type="bibr" rid="B1">Biggar Robert et al., 2007</xref>; <xref ref-type="bibr" rid="B12">Piketty et al., 2012</xref>). As a result, we attempted to modify the molecular structure of the HIV integrase inhibitors for anti-tumor activity. Due to its relatively strong anti-HIV activity and good safety and tolerability, dolutegravir was investigated in this study. In our study, we introduced 1,2,3-triazole groups into the structure of dolutegravir by click reaction. 1,2,3-Triazole is an important nitrogen-containing heterocyclic compound. Because1,2,3-triazole has amide isosteres and a stable rigid plane and can be prepared efficiently using a click reaction, it has been widely used for the modification of drug molecules, especially for the development of novel anti-tumor drugs (<xref ref-type="bibr" rid="B16">Wu et al., 2017</xref>; <xref ref-type="bibr" rid="B14">Sainas et al., 2019</xref>; <xref ref-type="bibr" rid="B8">Madasu et al., 2020</xref>; <xref ref-type="bibr" rid="B11">Pan et al., 2020</xref>; <xref ref-type="bibr" rid="B15">Tangadanchu et al., 2020</xref>). For example, as show in <xref ref-type="fig" rid="F2">Figure 2</xref>, one research group synthesized a series of homoerythrina alkaloid derivatives containing 1,2,3-triazole. Among them, compound <bold>10n</bold> showed a relatively strong inhibitory effect on A549 cells (IC<sub>50</sub> &#x3d; 1.89&#xa0;&#x3bc;M), which was stronger than harringtonine (IC<sub>50</sub> &#x3d; 10.55&#xa0;&#x3bc;M), pemetrexed (IC<sub>50</sub> &#x3d; 3.39&#xa0;&#x3bc;M), and rucaparib (IC<sub>50</sub> &#x3d; 4.91&#xa0;&#x3bc;M). Compound <bold>10n</bold> effectively arrested the cell cycle at the S phase, thus inducing apoptosis (apoptosis rate: 46%) and effectively inhibiting cell proliferation (<xref ref-type="bibr" rid="B7">Li et al., 2020</xref>).The research group led by Kamal modified the pyridine-sulfonamide derivative E7010 by replacing the benzenesulfonic acid structure with a 1,2,3-triazole moiety. Among the products, compound <bold>7f</bold> showed a strong inhibitory effect on A549 cells (IC<sub>50</sub> &#x3d; 1.023&#xa0;&#x3bc;M), and in addition, it arrested the cell cycle at the G2/M phase, thus inducing apoptosis of A549 cells. Detection of the mitochondrial membrane potential further confirmed the induction of apoptosis by compound <bold>7f</bold>. Molecular docking studies indicated that compound <bold>7f</bold> targeted the colchicine site of <italic>&#x3b2;</italic>-tubulin, and the mode of action was similar to that of E7010. Furthermore, the inhibitory effect of <bold>7f</bold> on <italic>&#x3b2;</italic>-tubulin (IC<sub>50</sub>: 2.04&#xa0;&#xb5;M) was equivalent to that of E7010 (IC<sub>50</sub> &#x3d; 2.15&#xa0;&#xb5;M) (<xref ref-type="bibr" rid="B13">Prasad et al., 2019</xref>). Because the epidermal growth factor receptor (EGFR) inhibitor icotinib has a structural feature of a terminal alkyne, it reacted with 3-chlorophenyl azide to produce compound <bold>a7</bold>, which showed excellent inhibitory effects on mutant lung cancer cells (PC-9) and wild-type lung cancer cells (A549), and had a stronger effect than icotinib (<xref ref-type="bibr" rid="B10">Mao et al., 2020</xref>). Compound <bold>a7</bold> downregulated the expression of caspase-3, causing fragmentation, pyknosis, and dense hyperchromasia of nuclei in A549 cells, inducing apoptosis and arresting A549 cells at the G2/M phase.</p>
<fig id="F2" position="float">
<label>FIGURE 2</label>
<caption>
<p>The structures of compounds <bold>10n</bold>, <bold>7f</bold> and <bold>a7</bold>.</p>
</caption>
<graphic xlink:href="fphar-14-1238587-g002.tif"/>
</fig>
<p>Therefore, a series of 1,2,3-triazoles derivatives were designed and synthesized by click reaction using dolutegravir as the parent nucleus according to the principle of bioactive substructure splicing. We used CCK-8 method to evaluate the anti-proliferative activity of the target compounds on lung carcinoma cell line A549.</p>
</sec>
<sec id="s2">
<title>2 Chemistry</title>
<p>In this route, 1-(2,2-dimethoxyethyl)-5-methoxy-6-(methoxycarbonyl)-4-oxo-1,4-dihydropyridine-3-carboxylic acid (<bold>1</bold>) was used as raw material and it was hydrolyzed under formic acid. The <italic>(R)</italic>-3 aminobutanol was added directly to the vacuum concentration and the mixture was refluxed in acetonitrile to give compound <bold>2</bold>. Compound <bold>2</bold> was condensed with 3-amine phenylacetylene to obtain terminal alkyne compound <bold>3</bold>. Compound <bold>3</bold> was reacted with azide compounds of different substituents to obtain 14 novel structure target compounds <bold>4a-4n</bold> as shown in <xref ref-type="fig" rid="F3">Figure 3</xref> and <xref ref-type="table" rid="T1">Table 1</xref>. The structures of the target compound were confirmed through <sup>1</sup>H and <sup>13</sup>C nuclear magnetic resonance spectroscopy.</p>
<fig id="F3" position="float">
<label>FIGURE 3</label>
<caption>
<p>The reaction routes to compounds <bold>4a</bold>-<bold>4n</bold>.</p>
</caption>
<graphic xlink:href="fphar-14-1238587-g003.tif"/>
</fig>
<table-wrap id="T1" position="float">
<label>TABLE 1</label>
<caption>
<p>R-group of compounds 4a-4n.</p>
</caption>
<table>
<thead valign="top">
<tr>
<th align="center">Compd no.</th>
<th align="center">n</th>
<th align="center">R<sub>1</sub>
</th>
<th align="center">R<sub>2</sub>
</th>
<th align="center">R<sub>3</sub>
</th>
<th align="center">R<sub>4</sub>
</th>
<th align="center">Compd no.</th>
<th align="center">n</th>
<th align="center">R<sub>1</sub>
</th>
<th align="center">R<sub>2</sub>
</th>
<th align="center">R<sub>3</sub>
</th>
<th align="center">R<sub>4</sub>
</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="center">4a</td>
<td align="center">0</td>
<td align="center">F</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">4h</td>
<td align="center">0</td>
<td align="center">CF<sub>3</sub>
</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">CF<sub>3</sub>
</td>
</tr>
<tr>
<td align="center">4b</td>
<td align="center">0</td>
<td align="center">CH<sub>3</sub>
</td>
<td align="center">NO<sub>2</sub>
</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">4i</td>
<td align="center">0</td>
<td align="center">OCH<sub>3</sub>
</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">H</td>
</tr>
<tr>
<td align="center">4c</td>
<td align="center">0</td>
<td align="center">H</td>
<td align="center">CH<sub>3</sub>
</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">4j</td>
<td align="center">0</td>
<td align="center">Br</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">H</td>
</tr>
<tr>
<td align="center">4d</td>
<td align="center">0</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">F</td>
<td align="center">H</td>
<td align="center">4k</td>
<td align="center">0</td>
<td align="center">Cl</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">H</td>
</tr>
<tr>
<td align="center">4e</td>
<td align="center">0</td>
<td align="center">CH<sub>2</sub>CH<sub>3</sub>
</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">4L</td>
<td align="center">0</td>
<td align="center">I</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">H</td>
</tr>
<tr>
<td align="center">4f</td>
<td align="center">0</td>
<td align="center">H</td>
<td align="center">OCH<sub>3</sub>
</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">4m</td>
<td align="center">1</td>
<td align="center">Br</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">H</td>
</tr>
<tr>
<td align="center">4g</td>
<td align="center">0</td>
<td align="center">H</td>
<td align="center">CF<sub>3</sub>
</td>
<td align="center">H</td>
<td align="center">H</td>
<td align="center">4n</td>
<td align="center">1</td>
<td align="center">H</td>
<td align="center">Br</td>
<td align="center">H</td>
<td align="center">H</td>
</tr>
</tbody>
</table>
</table-wrap>
</sec>
<sec sec-type="results|discussion" id="s3">
<title>3 Results and discussion</title>
<sec id="s3-1">
<title>3.1 Compounds 4a-4n suppressed cancer cells viability</title>
<p>In order to investigate the anti-proliferative activity of dolutegravir-1,2,3-triazole derivatives to lung carcinoma cell, we performed CCK8 assay to detect the effects of all the compounds on the cell viability of A549 cell line. We measured and calculated the half-maximal inhibitory concentration (IC<sub>50</sub>) of all the compounds. As showed in <xref ref-type="table" rid="T2">Table 2</xref>, <bold>4b</bold> and <bold>4g</bold> was suggested as the most highly active compound against A549 cell with IC<sub>50</sub> values at 8.72 &#xb1; 0.11 and 12.97 &#xb1; 0.32&#xa0;&#x3bc;M, respectively. LO2 and BESA-2b cells were a kind of normal cell lines which was used as a control to make a comparison with cancer cell lines and were treated with compounds <bold>4b</bold> and <bold>4g</bold> at the concentration of 20&#xa0;&#x3bc;M for 48&#xa0;h. The cell viabilities of LO2 cell for compounds <bold>4b</bold> and <bold>4g</bold> were 55.37% and 79.49%, and the cell viabilities of BESA-2b cell for compounds <bold>4b</bold> and <bold>4g</bold> were 61.57% and 76.42%.</p>
<table-wrap id="T2" position="float">
<label>TABLE 2</label>
<caption>
<p>The half-maximal inhibitory concentration (IC<sub>50</sub>) of all the compounds.</p>
</caption>
<table>
<thead valign="top">
<tr>
<th rowspan="2" align="center">Compd no.</th>
<th align="center">IC<sub>50</sub>, &#xb5;M, 48h</th>
<th rowspan="2" align="center">Compd no.</th>
<th align="center">IC<sub>50</sub>, &#xb5;M, 48h</th>
</tr>
<tr>
<th align="center">A549</th>
<th align="center">A549</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="center">4a</td>
<td align="center">&#x3e;50</td>
<td align="center">4h</td>
<td align="center">13.63 &#xb1; 1.79</td>
</tr>
<tr>
<td align="center">4b</td>
<td align="center">8.72 &#xb1; 0.11</td>
<td align="center">4i</td>
<td align="center">17.34 &#xb1; 0.73</td>
</tr>
<tr>
<td align="center">4c</td>
<td align="center">27.75 &#xb1; 0.56</td>
<td align="center">4j</td>
<td align="center">&#x3e;50</td>
</tr>
<tr>
<td align="center">4d</td>
<td align="center">&#x3e;50</td>
<td align="center">4k</td>
<td align="center">&#x3e;50</td>
</tr>
<tr>
<td align="center">4e</td>
<td align="center">20.67 &#xb1; 0.23</td>
<td align="center">4L</td>
<td align="center">33.66 &#xb1; 0.68</td>
</tr>
<tr>
<td align="center">4f</td>
<td align="center">44.34 &#xb1; 1.21</td>
<td align="center">4m</td>
<td align="center">&#x3e;50</td>
</tr>
<tr>
<td align="center">4g</td>
<td align="center">12.97 &#xb1; 0.32</td>
<td align="center">4n</td>
<td align="center">&#x3e;50</td>
</tr>
<tr>
<td align="left"/>
<td align="left"/>
<td align="center">DTG</td>
<td align="center">&#x3e;50</td>
</tr>
</tbody>
</table>
</table-wrap>
</sec>
<sec id="s3-2">
<title>3.2 Compounds 4b and 4g inhibited proliferation of cancer cells</title>
<p>To further assess the anti-proliferative activity of dolutegravir derivatives, we utilized LIVE/DEAD staining. Specifically, A549 cells were treated with 5&#xa0;&#x3bc;M, 10&#xa0;&#x3bc;M, or 20&#xa0;&#x3bc;M concentrations of <bold>4b</bold> or <bold>4g</bold> for 24&#xa0;h, and subsequently imaged and counted to distinguish between live and dead cells. As demonstrated in <xref ref-type="fig" rid="F4">Figure 4</xref>, live A549 cells were significantly reduced in a dose-dependent manner following treatment with either <bold>4b</bold> or <bold>4g</bold>. Moreover, the ratio of dead/live cells was also found to increase substantially with increasing concentration.</p>
<fig id="F4" position="float">
<label>FIGURE 4</label>
<caption>
<p>Compounds 4b and 4g inhibited proliferation of cancer cells. <bold>(A)</bold> Fluorescence images stained with the LIVE/DEAD kit of A549 cells treated with 5&#xa0;&#x3bc;M, 10&#xa0;&#x3bc;M, 20&#xa0;&#x3bc;M of <bold>4b</bold>. <bold>(B)</bold> Fluorescence images stained with the LIVE/DEAD kit of A549 cells treated with 5&#xa0;&#x3bc;M, 10&#xa0;&#x3bc;M, 20&#xa0;&#x3bc;M of <bold>4g</bold>. <bold>(C)</bold> Plate clone staining of A549 cells treated with different concentrations of <bold>4b</bold> and <bold>4g</bold>. Data are presented as mean &#xb1; SE. &#x2a;<italic>p</italic> &#x3c; 0.05.</p>
</caption>
<graphic xlink:href="fphar-14-1238587-g004.tif"/>
</fig>
<p>To validate the impact of <bold>4b</bold> and 4g on cell proliferation, we employed a plate clone formation assay. In this assay, A549 cells were treated with varying concentrations (0, 2, 4, 8, 16, and 32&#xa0;&#x3bc;M) of either <bold>4b</bold> or <bold>4g</bold>. Our results indicated that compound <bold>4b</bold> had no discernible effect on the A549 cell colony formation experiment on the plate. In contrast, compound <bold>4g</bold> exhibited anti-proliferative activity in a dose-dependent manner across all cell lines tested, including A549.</p>
</sec>
<sec id="s3-3">
<title>3.3 Compounds 4b and 4g induced apoptosis of cancer cells</title>
<p>Since dolutegravir derivatives could repress cancer cells proliferation, to explore whether they had effects on cell apoptosis, the apoptosis analysis was performed. A549 cells treated with different concentrations of <bold>4b</bold> or <bold>4g</bold> were stained with Annexin V-FITC and PI, and the numbers of apoptosis cells were analyzed by the flow cytometry. As illustrated, for A549 cells, compound <bold>4b</bold> showed little influence on cell apoptosis (<xref ref-type="fig" rid="F5">Figure 5A</xref>). In addition, A549 cells treated with 16&#xa0;&#x3bc;M of <bold>4g</bold> for 48h displayed a significant increase in the percentage of apoptosis but had no changes when treated with 2&#xa0;&#x3bc;M, 4&#xa0;&#x3bc;M or 8&#xa0;&#x3bc;M of <bold>4g</bold> (<xref ref-type="fig" rid="F5">Figure 5B</xref>).</p>
<fig id="F5" position="float">
<label>FIGURE 5</label>
<caption>
<p>Compounds 4b and 4g induced apoptosis of cancer cells. Apoptotic cells of A549 cells treated with 4b <bold>(A)</bold> and 4g <bold>(B)</bold> determined by flow cytometry. Data are presented as mean &#xb1; SE. &#x2a;<italic>p</italic> &#x3c; 0.05.</p>
</caption>
<graphic xlink:href="fphar-14-1238587-g005.tif"/>
</fig>
</sec>
<sec id="s3-4">
<title>3.4 Compounds 4b and 4g affected protein expressions of key signaling pathways</title>
<p>To determine the role of dolutegravir derivatives in regulating the development of cell proliferation, key proteins expressions which were involved in cell growth progresses were examined, including autophagy, apoptosis, cell cycle and DNA damage (<xref ref-type="fig" rid="F6">Figure 6</xref>). Ubiquitin like molecule light chain 3 (LC3) is a key marker of autophagy, our results showed that the expression of LC3 was significantly increased after compound 4g treated while had no difference after compound 4b treated in A549 cells. Caspase3, one of the key proteins in regulating apoptosis, however, was not changed in cancer cells when added <bold>4b</bold> or <bold>4g</bold> (<xref ref-type="fig" rid="F6">Figure 6</xref>). Cell cycle related genes including CyclinD, CyclinE or &#x3b2;-catenin also showed no differences with <bold>4b</bold> or <bold>4g</bold> treatment in A549 cells. In A549 cells, &#x3b3;-H2AX was induced when treating with <bold>4g</bold> and PARP showed no differences with <bold>4b</bold> or <bold>4g</bold> treatment.</p>
<fig id="F6" position="float">
<label>FIGURE 6</label>
<caption>
<p>Compounds 4b and 4g affected protein expressions of key signaling pathways. Western blotting of LC3, caspase3, Cyclin D, Cyclin E, &#x3b2;-catenin, &#x3b3;-H2AX, PARP in A549 cells treated with <bold>4b</bold> and <bold>4g</bold>. Top, Western blot; bottom, quantitative measurements relative to ACTIN. Data are presented as mean &#xb1; SE. &#x2a;<italic>p</italic> &#x3c; 0.05.</p>
</caption>
<graphic xlink:href="fphar-14-1238587-g006.tif"/>
</fig>
</sec>
</sec>
<sec sec-type="conclusion" id="s4">
<title>4 Conclusion</title>
<p>In this study, based on the modification of the structure of dolutegravir, we introduced 1,2,3-triazole moieties with different substituted groups and obtained 14 dolutegravir-1,2,3-triazole derivatives. The activity of A549 cells treated with the derivatives was examined, and most compounds showed strong inhibitory effects. Among them, compounds <bold>4b</bold> and <bold>4g</bold> were the most effective, and inhibited the growth of A549 cells with IC<sub>50</sub> values of 8.72 &#xb1; 0.11&#xa0;&#x3bc;M and 12.97 &#xb1; 0.32&#xa0;&#x3bc;M, respectively. In addition, compound 4g induced apoptosis and clonal suppression in A549 tumor cells. Compound <bold>4g</bold> also activated the LC3 signaling pathway to induce autophagy in tumor cells, and activated the &#x3b3;-H2AX signaling pathway to induce DNA damage in tumor cells. This research has guiding significance for the conversion of non-anti-tumor clinical drugs into lead compounds with anti-tumor activity.</p>
</sec>
<sec id="s5">
<title>5 Experimental</title>
<sec id="s5-1">
<title>5.1 Materials and chemistry</title>
<p>The dolutegravir-1,2,3-triazole derivative was synthesised in-house. All the reagents and solvents used were obtained from a commercially available source. The <sup>1</sup>H and <sup>13</sup>C NMR spectra were acquired in a DMSO-<italic>d</italic>
<sub>
<italic>6</italic>
</sub> solution using a Bruker 400&#xa0;MHz or 600&#xa0;MHz NMR spectrometer. LC-MS instrument was carried out using a Waters ZQ 2000. Dulbecco&#x2019;s modified Eagle medium (DMEM), RPMI 1640 Medium, Fetal bovine serum (FBS) and penicillin/streptomycin were purchased from Gibco (Grand Island, NY, United States).Enhanced Cell Counting Kit-8, Calcein/PI Live/Dead Viability Assay Kit and Giemsa dye were obtained from Beyotime Biotechnology (Shanghai, China). Annexin V-FITC/Propidium iodide (PI) staining kit and Matrigel Matrix were provided by BD Biosciences (Franklin Lake, New Jersey, United States).</p>
<sec id="s5-1-1">
<title>5.1.1 Synthesis of (4R,12aS)-3,4,6,8,12,12a-hexahydro-7-methoxy-4-methyl-6,8-dioxo-2H-pyridine [1&#x2032;,2&#x2032;: 4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxylic acid (Compound 2)</title>
<p>
<inline-graphic xlink:href="fphar-14-1238587-fx1.tif"/>
</p>
<p>In a reaction flask, 1-(2,2-dimethoxyethyl)-1,4-dihydro-3-methoxy-4-oxo-2,5-pyridinedicarboxylic acid-2-methyl ester (compound <bold>1</bold>, 30&#xa0;g, 0.1&#xa0;mol) was added to 150&#xa0;mL of anhydrous formic acid. The reaction was carried out at 65&#xb0;C with stirring and under argon atmosphere. The reaction was completed at about 3&#xa0;h when the starting material was used up as monitored with TLC. Under the vacuum, concentrated and evaporate formic acid at 45&#xb0;C to give a crude oil. Add 150&#xa0;mL of acetonitrile to the crude oil to dissolve with stirring. Added R-3-aminobutanol (12.5&#xa0;g, 0.14&#xa0;mol) and stirred for 10&#xa0;min. Then the temperature was raised to an internal temperature of 82&#xb0;C and continue stir for 2&#xa0;h. The reaction completed at this time as monitored with TLC. Concentrate to remove most of the solvent at 45&#xb0;C. Added 200&#xa0;mL of dichloromethane, and then 100&#xa0;mL water while stirring. Used 2N HCl to adjust the pH to 1-2, stir for 10&#xa0;min, then separated the lower organic phase. The upper aqueous phase was extracted three times with 50&#xa0;mL of dichloromethane. Combined all organic phases and washed three times with 50&#xa0;mL of saturated NaCl solution. Concentrated the mixture under vacuum to give a crude product. It was then purified by recrystallization using methanol to gave 21&#xa0;g of pure product (Compound <bold>2</bold>), yield 68.7%; <sup>1</sup>H NMR (400&#xa0;MHz, CDCl<sub>3</sub>): &#x3b4; 8.43 (s, 1H), 5.30 (t, J<sub>1</sub> &#x3d; 4.0 Hz, J<sub>2</sub> &#x3d; 4.0 Hz, 1H), 5.02 (t, J<sub>1</sub> &#x3d; 4.0Hz, J<sub>2</sub> &#x3d; 8.0Hz, 1H), 4.41 (dd, J<sub>1</sub> &#x3d; 4.0Hz, J<sub>2</sub> &#x3d; 4.0Hz, 1H), 4.27 (dd, J<sub>1</sub> &#x3d; 8.0Hz, J<sub>2</sub> &#x3d; 4.0Hz, 1H), 4.08 (s, 3H), 4.03&#x2013;3.99 (m, 2H), 2.25&#x2013;2.16 (m, 1H), 1.56 (d, J &#x3d; 12.0Hz, 1H), 1.39 (d, J &#x3d; 8.0Hz, 3H). <sup>13</sup>C NMR (100&#xa0;MHz, CDCl<sub>3</sub>): &#x3b4; 176.39, 165.85, 155.00, 153.90, 142.78, 130.66, 116.08, 75.97, 62.65, 61.48, 53.89, 44.93, 29.37, 16.06.</p>
</sec>
<sec id="s5-1-2">
<title>5.1.2 General synthetic procedure for compound 3</title>
<p>
<inline-graphic xlink:href="fphar-14-1238587-fx2.tif"/>
</p>
<p>Compound <bold>2</bold> (5&#xa0;g), 3-aminophenylacetylene (3.69g), HATU (13&#xa0;g), DIPEA (8.2&#xa0;g) and solvent DMF 250&#xa0;mL were added to a 500&#xa0;mL reaction flask at room temperature and stirred under nitrogen protection for 24&#xa0;h. Thin layer chromatography (TLC) was used for monitoring. After 24&#xa0;h, the reaction completed and the reaction solution was light brown. DMF was removed by vacuum concentration, dichloromethane was added to extract the reaction solution (150&#xa0;mL &#xd7; 3).Combine all organic solutions, wash them with saturated sodium chloride (150&#xa0;mL &#xd7; 2) to pH &#x3d; 7, and the viscous brownish yellow liquid was obtained by vacuum distillation. Under ultrasonic vibration, methanol was slowly added drop by drop, and solid precipitated. After that, it was left to stand, filtered and dried to obtain the compound <bold>3</bold>, 4.7&#xa0;g, yield 71.2%.</p>
</sec>
<sec id="s5-1-3">
<title>5.1.3 General synthetic procedure for compounds 4a-4n</title>
<p>
<inline-graphic xlink:href="fphar-14-1238587-fx3.tif"/>
</p>
<p>In the reaction flask, compound <bold>3</bold> (3&#xa0;mmol), substituted azide (3.6&#xa0;mmol), TERT butanol 70&#xa0;mL, water 70&#xa0;mL, tetrahydrofuran 70&#xa0;mL, anhydrous copper sulfate (1.2&#xa0;g, 6&#xa0;mmol) and sodium ascorbate (0.36&#xa0;g, 1&#xa0;mmol) were successively added, and stirred and refluxed at 70&#xb0;C for 6&#xa0;h. After the reaction was completed (monitored by TLC), use dichloromethane (100&#xa0;mL &#xd7; 3) to extract, combine the organic solution and wash with saturated sodium chloride aqueous solution (100&#xa0;mL &#xd7; 2). The combined organic layer was washed with brine (100&#xa0;mL &#xd7; 2), dried over sodium sulfate, and concentrated <italic>in vacuo</italic> to give the crude product. Recrystallization in ethyl acetate produced the desired compound which was pure enough for further characterization and anti-tumor study.</p>
<p>The spectroscopic characterization of compounds <bold>4a</bold>-<bold>4n</bold> is provided as Supporting Material Data.</p>
</sec>
</sec>
<sec id="s5-2">
<title>5.2 Biological study</title>
<sec id="s5-2-1">
<title>5.2.1 Cell culture</title>
<p>Human lung cancer cell lines A549 was obtained from ATCC. Cells were cultured in DMEM or RPMI 1640 medium containing 10% FBS and 1% penicillin/streptomycin at 37&#xa0;&#xb0;C with a 5% CO<sub>2</sub>-humidified atmosphere.</p>
</sec>
<sec id="s5-2-2">
<title>5.3.2 Cell viability assay</title>
<p>CCK8 assay was used to measure cell viability. Cells with a density of 1 &#xd7; 10<sup>4</sup> cells/well were seeded on the 96-well plates. After adhesion, cells were treated with different diluted compounds or vehicle control DMSO and continue cultured for 48&#xa0;h respectively. Then, CCK8 reagent was added for 1&#xa0;hour incubation at 37&#xb0;C with 5% CO<sub>2</sub>. Absorbance was measured using a Microplate spectrophotometer (Thermo) at 450&#xa0;nm. The ratio of cell viability of control was taken as 100%. For IC<sub>50</sub>, cells were treated with different concentrations of compounds (0, 0.5, 2, 8, 16, 32&#xa0;&#x3bc;M) for 48&#xa0;h and cell viability was determined to calculate the inhibition percentage. The CCK-8 assay was conducted three times and the repetitions in each time were at least three. Then IC<sub>50</sub> of compounds were investigated using the prism statistical software.</p>
</sec>
<sec id="s5-2-3">
<title>5.3.3 Live and dead cells measurement</title>
<p>A549 cells with a density of 5 &#xd7; 10<sup>3</sup> cells/well were seeded on the 96-well plates. Then different concentrations (0, 5, 10, 20&#xa0;&#x3bc;M) of <bold>4b</bold> or <bold>4g</bold> were treated for 24&#xa0;h. Cells were then stained with the LIVE/DEAD Assay Kit, observed and photographed using the fluorescent microscope.</p>
</sec>
<sec id="s5-2-4">
<title>5.3.4 Plate clone formation assay</title>
<p>A549 cells were seeded into 6-well plates at a density of 200&#x2013;500 cells/well. After 10&#xa0;days culture, cells were added with <bold>4b</bold> or <bold>4g</bold> at different concentrations (0, 2, 4, 8, 16, 32&#xa0;&#x3bc;M) for 48&#xa0;h. Then cells were fixed by 4% paraformaldehyde and stained by Giemsa dye. An optical microscope was used to photographed cells and counted the clone numbers.</p>
</sec>
<sec id="s5-2-5">
<title>5.3.5 Apoptosis assay</title>
<p>A549 cells were cultured in 6-well plates with a density of 3 &#xd7; 10<sup>5</sup> cells/well. Different concentrations of 4b or 4g were added to cells for 48h respectively. The concentrations were 0, 2, 4, 8, and 16&#xa0;&#x3bc;M for A549 cells. After treatment, Annexin V-FITC Apoptosis Detection Kit was used to determine the apoptotic ratio and FlowJo software v10 was used to analyze.</p>
</sec>
<sec id="s5-2-6">
<title>5.3.6 Western blot</title>
<p>Protein expression levels were measured by Western blot. A549 cells were cultured in 12-well plates and different concentrations (0, 2, 4, 8&#xa0;&#x3bc;M) of <bold>4b</bold> and <bold>4g</bold> were added for 48h. Proteins were extracted from whole cells using radioimmunoprecipitation assay (RIPA) buffer containing protease/phosphatase inhibitor cocktail (CST). 10%&#x2013;15% sodium dodecyl sulfate polyacrylamide gel electrophoresis and nitrocellulose membranes (Millipore) were used to separated and collected proteins. Antibodies used include, LC3 (3868s, CST), Caspase3 (9662, CST), cyclin D (2922s, CST), cyclin E (20808s, CST), &#x3b3;H2AX (9718s, CST), &#x3b2;-Catenin (9562s, CST), PARP (46D11, CST), and &#x3b2;-actin (4967s, CST).</p>
</sec>
<sec id="s5-2-7">
<title>5.3.7 Statistical analyses</title>
<p>Data were conducted using Graph Prim 7.0.A two-tailed Student&#x2019;s t-test or one-way analysis of variance followed by a Student-Newman-Keuls (SNK) test were used to assess significant differences. Values of <italic>p</italic> &#x3c; 0.05 were considered statistically significant.</p>
</sec>
</sec>
</sec>
</body>
<back>
<sec sec-type="data-availability" id="s6">
<title>Data availability statement</title>
<p>The original contributions presented in the study are included in the article/<xref ref-type="sec" rid="s11">Supplementary Materials</xref>, further inquiries can be directed to the corresponding author/s.</p>
</sec>
<sec id="s7">
<title>Author contributions</title>
<p>All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.</p>
</sec>
<sec id="s8">
<title>Funding</title>
<p>This work was supported by National Natural Science Foundation of China (82170606), Basic Research Project of Key Scientific Research Projects of Universities in Henan Province (23ZX006), Shenzhen Science and Technology Program (No. JCYJ20210324115208024), Shenzhen Outbound Postdoctoral Research Grant (No. CZBSHKYJJ002), The Key Scientific Research Projects of Universities in Henan Province (23B310001).</p>
</sec>
<sec sec-type="COI-statement" id="s9">
<title>Conflict of interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec sec-type="disclaimer" id="s10">
<title>Publisher&#x2019;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
<sec id="s11">
<title>Supplementary material</title>
<p>The Supplementary Material for this article can be found online at: <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fphar.2023.1238587/full#supplementary-material">https://www.frontiersin.org/articles/10.3389/fphar.2023.1238587/full&#x23;supplementary-material</ext-link>
</p>
<supplementary-material xlink:href="DataSheet2.docx" id="SM1" mimetype="application/docx" xmlns:xlink="http://www.w3.org/1999/xlink"/>
<supplementary-material xlink:href="DataSheet1.docx" id="SM2" mimetype="application/docx" xmlns:xlink="http://www.w3.org/1999/xlink"/>
</sec>
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