Rab27A对人乳腺癌细胞生物学特性的影响

Rab27A is involved in malignant phenotypes in human breast cancer cells by regulating the expression of related genes

背景与目的:Rab蛋白属Ras超家族中有超过60个成员的最大的一个亚家族。Rab27A是这一家族中唯一一个明确涉及到人类遗传性疾病的成员。本研究探讨Rab27A对人乳腺癌细胞生物学特性的影响及其机制。方法:构建含有Rab27A开放阅读框的真核表达质粒,通过脂质体转染的方法将其导入乳腺癌细胞MDA-MB-231,同时采用RNA干扰的方法下调Rab27A的表达。测定Rab27A上调及下调表达后乳腺癌细胞生长曲线、细胞周期分布、凋亡细胞比例、体外侵袭等生物学特性的变化,并采用RT-PCR方法来探讨Rab27A发挥作用的分子机制。结果:①Rab27A的表达水平随乳腺癌细胞侵袭转移能力的增强而增高。②上调Rab27A表达后导致乳腺癌细胞生长加速、S期细胞比例增多、凋亡细胞比例下降、体外侵袭能力增强。③CyclinD1、MMP-7和MMP-9基因表达水平与Rab27A表达呈正相关,而p16的表达与Rab27A的表达呈负相关。结论:Rab27A通过调节Cyclin D1、MMP-7、MMP-9和p16基因的表达,从而在乳腺癌细胞增殖、细胞周期分布、凋亡和侵袭中发挥作用。

Background and purpose： Rabs are members of Ras-related small GTPase superfamily. Rab27A is a unique member in the Rab family and has specific implications in human genetic diseases. We studied the potential role of Rab27A in proliferation, distribution of cell cycle, apoptosis and invasion of breast cancer cells and its mechanism（s）. Methods： The eukaryotic expression vector containing Rab27A open reading frame （ORF） pcDNA3.1 （ ＋ ） - Rab27A was constructed and transfected into MDA-MB-231 breast cancer cells. Then we detected the changes in terms of cell growth, cell cycle distribution, apoptosis and in vitro invasion capability before and after transfection. We also applied RT-PCR to investigate the molecular basis. Results： ① The expression of Rab27A was increased as invasive and metastatic ability increased in four human breast cancer cell lines. ② Overexpression of Rab27A can promote breast cancer cells to grow faster, increase the proportion of S phase cells, avoid apoptosis and invade in vitro. ③ Rab27A transfectants constitutively enhanced the expression of Cyclin D1, MMP-7 and MMP-9 in MDA-MB-231 cell lines, on the contrary, that of p16 were down-regulated constitutively. Reduced Rab27A expression by RNAi down-regulated the expression of Cyclin D1, MMP-7 and MMP-9, and up-regulated p16 expression. Conclusions： Rab27A can stimulate breast cancer cells to proliferate, increase the proportion of cells in S phase, avoid apoptosis and invade in vitro by regulating the expression of Cyclin D1, MMP-7, MMP-9 and p16.