Previous studies suggest the tumor suppressor role of long non-coding RNA (lncRNA) STXBP5-AS1 in cervical and gastric cancer, but its expression pattern and functional mechanism are still elusive in pancreatic cancer (PC). Relative expression of STXBP5-AS1 in PC both in vivo and in vitro was analyzed by real-time PCR. IC50 of Gemcitabine was determined by the MTT assay. Cell proliferation in response to drug treatment was investigated by colony formation assay. Cell apoptosis was measured by both caspase-3 activity and Annexin V/PI staining. Cell invasion capacity was scored by the transwell assay in vitro, and lung metastasis was examined with the tail vein injection assay. Cell stemness was determined in vitro by sphere formation and marker profiling, respectively, and in vivo by limited dilution of xenograft tumor incidence. Subcellular localization of STXBP5-AS1 was analyzed with fractionation PCR. Association between STXBP5-AS1 and EZH2 was investigated by RNA-immunoprecipitation. The binding of EZH2 on ADGB promoter was analyzed by chromatin immunoprecipitation. The methylation was quantified by bisulfite sequencing. We showed downregulation of STXBP5-AS1 in PC associated with poor prognosis. Ectopic STXBP5-AS1 inhibited chemoresistance and metastasis of PC cells. In addition, STXBP5-AS1 compromised stemness of PC cells. Mechanistically, STXBP5-AS1 potently recruited EZH2 and epigenetically regulated neighboring ADGB transcription, which predominantly mediated the inhibitory effects of STXBP5-AS1 on stem cell-like properties of PC cells. Our study highlights the importance of the STXBP5-EZH2-ADGB axis in chemoresistance and stem cell-like properties of PC.

中文翻译：

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LncRNA STXBP5-AS1通过表观遗传抑制邻近雄红蛋白基因表达抑制胰腺癌的干细胞样特性

以往的研究表明长链非编码RNA（lncRNA）STXBP5-AS1在宫颈癌和胃癌中的抑癌作用，但其在胰腺癌（PC）中的表达模式和功能机制仍不清楚。通过实时 PCR 分析了体内和体外 PC 中 STXBP5-AS1 的相对表达。吉西他滨的 IC50 由 MTT 测定确定。通过集落形成试验研究响应于药物处理的细胞增殖。通过 caspase-3 活性和膜联蛋白 V/PI 染色测量细胞凋亡。通过体外transwell测定对细胞侵袭能力进行评分，并用尾静脉注射测定检查肺转移。细胞干性分别通过球体形成和标志物分析在体外确定，在体内通过异种移植肿瘤发生率的有限稀释来确定。用分级 PCR 分析 STXBP5-AS1 的亚细胞定位。STXBP5-AS1 和 EZH2 之间的关联通过 RNA 免疫沉淀进行了研究。通过染色质免疫沉淀分析 EZH2 与 ADGB 启动子的结合。通过亚硫酸氢盐测序定量甲基化。我们显示 PC 中 STXBP5-AS1 的下调与不良预后相关。异位 STXBP5-AS1 抑制 PC 细胞的化学抗性和转移。此外，STXBP5-AS1 损害了 PC 细胞的干性。从机制上讲，STXBP5-AS1 有效地招募 EZH2 并表观遗传调节邻近的 ADGB 转录，这主要介导了 STXBP5-AS1 对 PC 细胞干细胞样特性的抑制作用。我们的研究强调了 STXBP5-EZH2-ADGB 轴在 PC 的化学抗性和干细胞样特性中的重要性。