垂体促性腺激素腺瘤mTOR信号通路激活及雷帕霉素对肿瘤的抑制作用

Activation of mTOR signaling pathway in gonadotroph adenomas and rapamycin’s inhibition on the pituitary adenoma cells

目的研究垂体促性腺激素腺瘤(gonadotroph adenomas,GA)中mTOR信号通路蛋白的表达,初步探讨雷帕霉素抑制GA细胞增殖的机制。方法收集42例GA肿瘤标本,分为侵袭组(n=24)和非侵袭组(n=18),同时收集5例正常垂体组织作为正常组(n=5)。Western blot检测3组样本mTOR信号通路及下游相关蛋白的表达,MTS法检测不同浓度雷帕霉素对GT1-1及MMQ系细胞增殖的影响,Western blot检测不同浓度雷帕霉素对GT1-1细胞系mTOR通路相关蛋白及磷酸化水平表达的影响。结果在mTOR、P70S6K及4EBP1蛋白的表达上,3组标本之间差异无统计学意义(P>0.05);而在上述3种蛋白磷酸化水平的表达上,任意2组之间差异均有统计学意义(P <0.05),侵袭组表达最高。雷帕霉素对GT1-1细胞系的半数抑制率浓度为0.94 nmol/L,而MMQ系细胞的半数抑制率浓度为4.87 nmol/L。随着雷帕霉素浓度的升高,GT1-1细胞系中pmTOR、p-P70S6K及p-4EBP1的表达呈递减趋势(P <0.05);而对mTOR、P70S6K、4EBP1的表达无影响。结论 GA中mTOR信号通路蛋白呈过度表达,特别是在侵袭性肿瘤中。雷帕霉素可通过干预mTOR信号通路抑制GT1-1细胞系的增殖活性。

Objective To study the expression of proteins related with m TOR signaling pathway in pituitary gonadotroph adenomas(GA) and explore the mechanism of rapamycin inhibiting proliferation of GA cells preliminarily. Methods GA samples of 42 patients were collected and divided into invasive group(n = 24) and non-invasive group(n = 18). The normal pituitary tissues of 5 adults were collected as normal group. Western blot assay was used to detect the expression of proteins related with m TOR signaling pathway in 3 groups. MTS was used to detect the influence of rapamycin of different concentrations on GT1-1 and MMQ cell proliferation. Western blot assay was used to detect the influence of rapamycin of different concentrations on the expression of proteins and their phosphorylation types related with m TOR signaling pathway in GT1-1 cells. Results There was no difference in the expression of m TOR, P70S6K and 4 EBP1 between the 3 groups(P > 0.05). There was a significant difference in p-mTOR, p-4 EBP1 and p-P70S6K between every 2 groups( P < 0. 05). The expressions of phosphorylation activation form were highest in invasive group. The concentrations of rapamycin for 50% maximal effect of GT1-1 and MMQ cells were 0.94 and 4.87 nmol/L, respectively. The expression of p-mTOR, p-P70S6K and p-4 EBP1 in GT1-1 cells were gradually decreased with increase of the concentration of rapamycin(P < 0.05), but there was no influence of rapamycin on the expression of mTOR, P70S6K and 4 EBP1. Conclusions The m TOR signaling pathway could be significantly activated in GA, especially in invasive GA. Rapamycin can inhibit the proliferation of GT1-1 cells by intervening the m TOR signaling pathway.