Specific inhibition of mTOR pathway induces anti-proliferative effect and decreases the hormone secretion in cultured pituitary adenoma cells
Specific inhibition of mTOR pathway induces anti-proliferative effect and decreases the hormone secretion in cultured pituitary adenoma cells
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DOI：
10.1007/s11060-015-1895-x
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发表时间：
2015-08
影响因子：
3.9
通讯作者：
R. Xie;Wenqiang He;Ming Shen;Xuefei Shou;Yong-fei Wang;Wei-min Bao;Yao Zhao
中科院分区：
文献类型：
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作者：
R. Xie;Wenqiang He;Ming Shen;Xuefei Shou;Yong-fei Wang;Wei-min Bao;Yao Zhao
有证据表明垂体瘤可能对哺乳动物雷帕霉素靶蛋白（mTOR）抑制剂的抗增殖作用敏感，但其机制和作用尚不清楚，有必要发现特定的mTOR抑制（包括阻断mTOR功能和表达）是否对垂体瘤细胞产生任何影响。本研究的目的是利用一种mTOR shRNA慢病毒载体，观察特异性抑制mTOR是否诱导GH 3和MtT/E垂体腺瘤细胞的抗增殖作用以及GH和PRL激素分泌的减少。体外实验结果显示，转染mTOR shRNA后，GH 3和MtT/E细胞在1-6 d内的存活率均明显降低，GH和PRL的外分泌量也明显降低。进一步的研究结果提示，特异性抑制mTOR可能通过抑制GH 3细胞增殖，减少激素合成，而不是通过影响激素分泌过程，从而降低激素分泌。用mTOR激活剂磷脂酸（phosphatidic acid，PA）促进GH 3细胞的增殖和GH、PRL分泌，并用mTOR shRNA转染阻断PA的作用。此外，我们还在体外研究了PA处理和mTOR shRNA基因转染对GH 3细胞中mTOR通路中主要蛋白表达的影响，证实PA处理显著增加了scramble shRNA组中pmTOR、pS 6 K和p4 EBP 1的蛋白水平，而mTOR shRNA基因转染则阻断了蛋白水平的增加。转染mTOR shRNA后，PA组和非PA组mTOR的表达明显降低，pmTOR、pS 6 K和p4 EBP 1的表达明显降低。这些结果表明，特异性抑制mTOR通路诱导的抗增殖作用，并降低培养的垂体腺瘤细胞的GH和PRL激素的分泌，这可能是一个新的有前途的和潜在的治疗模式，对分泌型或非分泌型垂体腺瘤患者。
There are some evidences that pituitary tumors may be sensitive to the anti-proliferative effects of mammalian target of rapamycin (mTOR) inhibitors, while the mechanism and effects remains unclear, it is necessary to find if a specific mTOR inhibition, including the blocking of both mTOR function and expression, generate any effects on pituitary adenoma cells. The object of this study was to examine if specific inhibition of mTOR induced anti-proliferative effect and decreased the GH and PRL hormones secretion in GH3 and MtT/E pituitary adenoma cells by using a kind of mTOR shRNA lentiviral vector. The in vitro experiments results showed mTOR shRNA transfection robustly reduced the GH3 and MtT/E cells viability in all durations (1–6 days) we performed, also specifically decreased both GH and PRL hormones external secretion in GH3 cells. Further results suggested that specific inhibition of mTOR decreased the hormones secretion through anti-proliferation effects on GH3 cells and reducing the hormones synthesis, but not through affecting the process of hormones secretion. Then we used phosphatidic acid (PA), a kind of mTOR activator, to promote the cell proliferation and GH and PRL hormones secretion in GH3 cells while the effects were blocked by mTOR shRNA transfection. In addition, we examined in vitro effects of PA treatment and mTOR shRNA gene transfection on major proteins expressed in the mTOR pathway in GH3 cells, and confirmed that PA treatment significant increased the protein levels of pmTOR, pS6 K and p4EBP1 in the scramble shRNA group, while the increase of protein levels was blocked by mTOR shRNA gene transfection. Moreover, mTOR shRNA gene transfection definitely inhibited the expression of mTOR and reduced the expression of pmTOR, pS6K and p4EBP1 in either PA or no PA treatment groups. These findings indicated that specific inhibition of mTOR pathway induced anti-proliferative effect and decreased the GH and PRL hormones secretion in cultured pituitary adenoma cells, which may be a novel promising and potential treatment modality for patients with secreting or non-secreting pituitary adenomas.