Division of Gastroenterology and Hepatology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Institution of Digestive Disease, Key Laboratory of Gastroenterology and Hepatology, Ministry of Health (Shanghai Jiao Tong University), 145 Middle Shandong Rd., Shanghai, 200001, China.
Cell Biol Int. 2014 Jan;38(1):50-63. doi: 10.1002/cbin.10179. Epub 2013 Oct 10.
Deregulation of the mammalian target of rapamycin pathway (mTOR pathway) is associated with human cancer. The relationship between mTOR pathway and histone acetylation is still unclear in gastric cancer (GC). Immunohistochemistry was used to examine the phosphorylation of mTOR and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) in GC tissues. MKN45 and SGC7901 cells were treated with the mTOR inhibitor rapamycin (RAPA) alone or in combination with the phosphatidylinositol 3-kinase inhibitor LY294002 and the histone deacetylase (HDAC) inhibitor trichostatin A (TSA). Small interfering RNA (siRNA) technology was also used to knockdown mTOR. Phosphorylated mTOR and phosphorylated 4E-BP1 were expressed in 71.1% and 68.4% of the human GC tissues tested, respectively; significantly higher than the levels in para-cancerous tissues (50% and 57.9%) and normal tissues (44.6% and 29%). RAPA markedly inhibited cell proliferation, induced G1 cell cycle arrest, and reduced phosphorylation of p70 S6 protein kinase (p70S6K) and 4E-BP1 in GC cells, particularly when used in combination with LY294002 or TSA. The mRNA expression of the tumour suppressor gene p21(WAF1) increased significantly in GC cells treated with both RAPA and TSA. Histone acetylation also increased after RAPA and TSA treatment or siRNA knockdown of mTOR. Our findings suggest that the mTOR pathway is activated in GC, and also that inhibition of mTOR enhances the ability of TSA to suppress cell proliferation and lead to cell cycle arrest via increasing histone acetylation and p21(WAF1) transcription in human MKN45 and SGC7901 GC cells.
哺乳动物雷帕霉素靶蛋白（mTOR）途径的失调与人类癌症有关。mTOR 途径与组蛋白乙酰化在胃癌（GC）中的关系尚不清楚。免疫组织化学法检测 GC 组织中 mTOR 和真核翻译起始因子 4E 结合蛋白 1（4E-BP1）的磷酸化。单独或联合使用 mTOR 抑制剂雷帕霉素（RAPA）、磷脂酰肌醇 3-激酶抑制剂 LY294002 和组蛋白去乙酰化酶（HDAC）抑制剂曲古抑菌素 A（TSA）处理 MKN45 和 SGC7901 细胞。还使用小干扰 RNA（siRNA）技术敲低 mTOR。在检测的人 GC 组织中，磷酸化 mTOR 和磷酸化 4E-BP1 的表达分别为 71.1%和 68.4%；明显高于癌旁组织（50%和 57.9%）和正常组织（44.6%和 29%）。RAPA 显著抑制 GC 细胞增殖，诱导 G1 细胞周期停滞，并降低 p70 S6 蛋白激酶（p70S6K）和 4E-BP1 的磷酸化，特别是与 LY294002 或 TSA 联合使用时。RAPA 和 TSA 处理或 mTOR siRNA 敲低后，GC 细胞中肿瘤抑制基因 p21（WAF1）的 mRNA 表达显著增加。RAPA 和 TSA 处理或 mTOR siRNA 敲低后组蛋白乙酰化也增加。我们的研究结果表明，mTOR 途径在 GC 中被激活，并且抑制 mTOR 可通过增加组蛋白乙酰化和 p21（WAF1）转录来增强 TSA 抑制细胞增殖和导致细胞周期停滞的能力，从而在人 MKN45 和 SGC7901 GC 细胞中。
