Medical Research Center, Second Affiliated Hospital of Nantong University, Nantong, China.
Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.
Cancer Sci. 2021 May;112(5):1798-1810. doi: 10.1111/cas.14868. Epub 2021 Mar 19.
The G-protein-coupled receptor 126 (GPR126) may play an important role in tumor development, although its role remains poorly understood. We found that GPR126 had higher expression in most colorectal cancer cell lines than in normal colon epithelial cell lines, and higher expression levels in colorectal cancer tissues than in normal adjacent colon tissues. GPR126 knockdown induced by shRNA inhibited cell viability and colony formation in HT-29, HCT116, and LoVo cells, decreased BrdU incorporation into newly synthesized proliferating HT-29 cells, led to an arrest of cell cycle progression at the G1 phase in HCT-116 and HT-29 cells, and suppressed tumorigenesis of HT-29, HCT116, and LoVo cells in nude mouse xenograft models. GPR126 knockdown engendered decreased transcription and translation of histone deacetylase 2 (HDAC2), previously implicated in the activation of GLI1 and GLI2 in the Hedgehog signaling pathway. Ectopic expression of HDAC2 in GPR126-silenced cells restored cell viability and proliferation, GLI2 luciferase reporter activity, partially recovered GLI2 expression, and reduced the cell cycle arrest. HDAC2 regulated GLI2 expression and, along with GLI2, it bound to the PTCH1 promoter, as evidenced by a chip assay with HT-29 cells. Purmorphamine, a hedgehog agonist, largely restored the cell viability and expression of GLI2 proteins in GPR126-silenced HT-29 cells, whereas GANT61, a hedgehog inhibitor, further enhanced the GPR126 knockdown-induced inhibitory effects. Our findings demonstrate that GPR126 regulates colorectal cancer cell proliferation by mediating the expression of HDAC2 and GLI2, therefore it may represent a suitable therapeutic target for colorectal cancer treatment.
G 蛋白偶联受体 126（GPR126）可能在肿瘤发展中发挥重要作用，尽管其作用仍知之甚少。我们发现，GPR126 在大多数结直肠癌细胞系中的表达高于正常结肠上皮细胞系，在结直肠癌组织中的表达高于正常相邻结肠组织。shRNA 介导的 GPR126 敲低抑制 HT-29、HCT116 和 LoVo 细胞的细胞活力和集落形成，减少 BrdU 掺入新合成的增殖 HT-29 细胞，导致 HCT-116 和 HT-29 细胞的细胞周期进程停滞在 G1 期，并抑制 HT-29、HCT116 和 LoVo 细胞在裸鼠异种移植模型中的肿瘤发生。GPR126 敲低导致组蛋白去乙酰化酶 2（HDAC2）的转录和翻译减少，先前涉及 Hedgehog 信号通路中 GLI1 和 GLI2 的激活。在 GPR126 沉默细胞中异位表达 HDAC2 恢复了细胞活力和增殖、GLI2 荧光素酶报告基因活性，部分恢复了 GLI2 表达，并减少了细胞周期停滞。HDAC2 调节 GLI2 表达，并且与 GLI2 一起结合到 PTCH1 启动子上，正如 HT-29 细胞的芯片分析所示。 Hedgehog 激动剂 Purmorphamine 很大程度上恢复了 GPR126 沉默 HT-29 细胞中的细胞活力和 GLI2 蛋白表达，而 Hedgehog 抑制剂 GANT61 进一步增强了 GPR126 敲低诱导的抑制作用。我们的研究结果表明，GPR126 通过介导 HDAC2 和 GLI2 的表达来调节结直肠癌细胞的增殖，因此它可能代表结直肠癌治疗的合适治疗靶点。
