Signal transducer and activator of transcription 3 (STAT3) and STAT5 are the transcription factors that have been studied extensively in relevance to the development of cancers in humans. Suppression of either STAT3 or STAT5-mediated signaling events has been demonstrated to be effective in inducing cytotoxicity in cancer cells. Herein, new hybrids of triazolyl-indolo-quinoxaline are synthesized and examined for their effect on the activation of STAT3 and STAT5 pathways in gastric cancer (GC) cells. Among the newly synthesized compounds, 2,3-difluoro-6-((1-(3-fluorophenyl)-1H-1,2,3-triazol-5-yl)methyl)-6H-indolo[2,3-b]quinoxaline (DTI) displayed selective cytotoxicity against GC cells over their normal counterpart. Flow cytometric analysis, annexin-V-fluorescein isothiocyanate staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, live and dead assay, and caspase activation experiments suggested DTI as a potent inducer of apoptosis. The mechanistic approach revealed that DTI imparts cytotoxicity via downregulating the phosphorylation of STAT3^Y705 and STAT5^Y694/699. DTI significantly reduced the nuclear pool of STAT3/STAT5 and reduced the DNA interaction ability of STAT3/STAT5 as evidenced by immunofluorescence and electrophoretic mobility shift assay. Further investigation revealed that inhibitory effects towards STAT proteins were mediated through the suppression of upstream kinases such as JAK1, JAK2, and Src. Treatment of GC cells with pervanadate counteracted the DTI-driven STAT3/STAT5 inhibition suggesting the involvement of tyrosine phosphatase. Upon DTI exposure, there was a significant upregulation in the mRNA and protein expression of PTPεC, which is a negative regulator of the JAK-STAT pathway. Knockdown of PTPεC suppressed the DTI-induced STATs inhibition in GC cells. Taken together, triazolyl-indolo-quinoxaline is presented as a new inhibitor of the STAT3/STAT5 pathway in GC cells.

中文翻译：

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一种新的三唑基吲哚喹喔啉通过上调 PTPεC 消除 STAT3/5 通路来诱导胃癌细胞凋亡


信号转导和转录激活因子 3 (STAT3) 和 STAT5 是已被广泛研究与人类癌症发展相关的转录因子。抑制 STAT3 或 STAT5 介导的信号传导事件已被证明可有效诱导癌细胞的细胞毒性。在此，合成了三唑基-吲哚-喹喔啉的新杂合体，并检查了它们对胃癌 (GC) 细胞中 STAT3 和 STAT5 途径激活的影响。新合成的化合物中，2,3-二氟-6-((1-(3-氟苯基)-1H-1,2,3-三唑-5-基)甲基)-6H-吲哚并[2,3-b ] 喹喔啉 (DTI) 对 GC 细胞的选择性细胞毒性优于其正常细胞。流式细胞术分析、膜联蛋白-V-异硫氰酸荧光素染色、末端脱氧核苷酸转移酶 dUTP 缺口末端标记测定、活死测定以及 caspase 激活实验表明 DTI 是细胞凋亡的有效诱导剂。机制方法表明，DTI 通过下调 STAT3 ^Y705和 STAT5 ^Y694/699的磷酸化来赋予细胞毒性。免疫荧光和电泳迁移率变动分析表明，DTI 显着减少了 STAT3/STAT5 的核池，并降低了 STAT3/STAT5 的 DNA 相互作用能力。进一步的研究表明，对 STAT 蛋白的抑制作用是通过抑制上游激酶（例如 JAK1、JAK2 和 Src）来介导的。用过钒酸盐处理 GC 细胞可以抵消 DTI 驱动的 STAT3/STAT5 抑制，表明酪氨酸磷酸酶的参与。 DTI 暴露后，PTPεC 的 mRNA 和蛋白表达显着上调，PTPεC 是 JAK-STAT 通路的负调节因子。 PTPεC 的敲低抑制了 GC 细胞中 DTI 诱导的 STAT 抑制。总之，三唑基吲哚喹喔啉被认为是 GC 细胞中 STAT3/STAT5 通路的新抑制剂。