PI3Kp55γ调节亚基N末端对乳腺癌细胞增殖和侵袭能力的影响

Influence of the N-terminal of the p55γ regulatory subunit of phosphoinositide-3 kinase on proliferation and invasiveness in breast cancer cells

目的:研究磷脂酰肌醇3激酶(PI3K)调节亚基p55γN末端24个氨基酸表达对乳腺癌细胞增殖和侵袭转移的影响。方法:通过脂质体介导用pEGFPC1和pEGFPN24表达质粒转染MDA-MB-231细胞,建立表达稳定融合蛋白GFP-N24和GFP的细胞系;MTT法观察转染细胞的增殖情况;流式细胞术分析细胞周期;细胞侵袭实验观察N24p55γ对细胞侵袭力的影响;明胶酶谱实验观察N24p55γ表达对基质金属蛋白酶9(MMP9)活性的影响。结果:N24p55γ的表达抑制细胞体外增殖,使细胞生长速度减慢,细胞周期G0/G1期百分率由(42.1±1.637)%上升到(51.4±0.78)%,P<0.05。N24p55γ过表达抑制MDA-MB-231细胞的运动和迁移,与对照组细胞相比,差异有统计学意义,P<0.05;明胶酶谱实验结果显示,N24p55γ抑制活化型MMP-9的表达。结论:N24p55γ不仅能抑制乳腺癌细胞的体外增殖,而且抑制乳腺癌细胞的运动和迁移,抑制细胞周期以及肿瘤转移相关基因MMP-9表达和分泌可能是其发挥作用的主要机制。

OBJECTIVE： To investigate the possible role of the N- terminal 24 amino acids of p55γ in MDA-MB-231 human breast cancer ceils proliferation, migration and invasion in vitro. METHODS： Stable MDA-MB-231 cell lines expressing the N-terminal 24 amino acids-GFP fusion proteins （GFP N24） and the GFP protein were generated respectively. The growth of the stable transfected cells was determined by MTT assay and the cell cycle of these cells was assayed by flow cytometry. The ability of MDA-MB-231 cells to invade and migrate was evaluated by the Transwell coculture system. The activity of matrix metalloproteinase-9 （MMP-9） was determined by gelatin zymography. RESULTS： Plasmids encoding GFP-N24 and GFP were transfected into MDA-MB-231 cells and the clones, which can stably expressed GFP and GFP-N24 （designated as 231/C1 and 231/N24 respectively）, were established and further studied. Overexpression of the N terminal 24 amino acids of p557 inhibited cell proliferation in vitro. The percentage of 231/N24 cells in G0/G1 phase was （51.4 ± 0.78）%, significantly higher than the percentage of 231/Cl cells in G0/G1 phase （42.1±1. 637）% （P〈0.05）. Overexpression of the N terminal 24 amino acids of p557 markedly resulted in de crease of MDA-MB-231 cell migration compared with the control cells （P〈0.05）. Moreover, the N terminal 24 amino acids of p55γ inhibited activated MMP 9, which suggested that the N terminal 24 amino acids of p55γ might modulate MMP-9 activation. CONCLUSIONS： The results demonstrated that the N-terminal 24 amino acids of the p55γ not only inhibit the growth and proliferation of breast cancer cells, but also inhibit motility, migration and invasion of the cells. Moreover, the expression of the N-terminal 24 anino acids of p55γ decreased the expression and secretion of tumor metastasis related gene MMP-9.