腺病毒5型E1A基因对永生化人支气管上皮细胞生长的抑制作用及其机理

The Growth Inhibition of Adenovirus Type 5 E1A Gene on Immortalized Human Bronchial Epithelial Cell Line and Its Mechanism

腺病毒 5型早期区 1 A( Ad5E1 A)基因是新近发现的一个肿瘤抑制基因 .其产物 E1 A蛋白是多功能转录因子 ,它能从正、负 2个途径调控多种细胞基因的转录 ,具有降低体内致瘤性及抗转移等活性 .为了探讨 E1 A基因对代表肺癌癌前病变的永生化人支气管上皮细胞的生长是否具有抑制作用 ,构建了在真核细胞高表达 E1 A基因的重组质粒 p CEP4- E1 A.通过脂质体介导将 E1 A基因转入永生化人支气管上皮细胞第 1 68代 ( MP1 68)中 ,经潮霉素筛选 ,获得稳定表达 E1 A的永生化人支气管上皮细胞 ( MP1 68- E1 A) .结果表明 :E1 A基因的稳定表达抑制了 HER- 2 / neu基因的表达 .转染细胞 ( MP1 68- E1 A)回复扁平形态、恢复细胞生长的接触性抑制 ,细胞群体生长缓慢 (倍增时间是 MP1 68- vect细胞的 1 .41倍 ) ,细胞周期 G1期阻滞并出现凋亡 ,软琼脂集落形成抑制率达73.86% .结果说明 E1 A基因的稳定表达明显抑制了永生化人支气管上皮细胞的生长 .该作用可能与 E1 A抑制 HER- 2 / neu基因的表达及诱导永生化人支气管上皮细胞凋亡有关 .

Adenovirus type 5 E1A gene (Ad5E1A) has been found to be a tumor suppressor gene recently.The E1A products are positive or negative regulators for many other genes which are important in carcinogenesis and tumor metastasis.To study the effects of E1A gene on immortalized human bronchial epithelial cells (IHBEC),and make a preliminary study of gene prevention of lung cancer,1.77 kb E1A gene was subcloned into a mammalian expression vector pCEP4,and named pCEP4 E1A,which was then introduced into IHBEC (MP168) by lipofectamine.The cells resistant to hygromycin B were selected.The results showed that the E1A expressing IHBEC decreased the product of HER 2/neu,and the E1A transfected cells were relatively flat.G 1 arrest and apoptosis were observed in the E1A transfected cells.The expression of E1A significantly suppressed the growth rates and reduced anchorage independence of the E1A transfected cells.So it is concluded that E1A is able to significantly inhibit the growth of IHBEC via suppression of HER 2/neu expression and induction of apoptosis.