Repression of human papillomavirus oncogenes in HeLa cervical carcinoma cells causes the orderly reactivation of dormant tumor suppressor pathways
Repression of human papillomavirus oncogenes in HeLa cervical carcinoma cells causes the orderly reactivation of dormant tumor suppressor pathways
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DOI：
10.1073/pnas.97.23.12513
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发表时间：
2000-11-07
影响因子：
11.1
通讯作者：
DiMaio, D
中科院分区：
文献类型：
--
作者：
Goodwin, EC;DiMaio, D
大多数宫颈癌表达高危人乳头瘤病毒(HPVs)E6和E7蛋白，它们中和细胞肿瘤抑制功能。为了确定从宫颈癌细胞中去除E6和E7蛋白的后果，我们用表达牛乳头瘤病毒E2蛋白的重组病毒感染了含有HPV18DNA的宫颈癌细胞株HeLa细胞。E2蛋白的表达导致HPVE6和E7的表达迅速受到抑制，大约12h后，细胞DNA合成受到严重抑制。在E6/E7抑制后不久，出现了戏剧性的P53转录后诱导。两个p53反应基因mdm2和p21的诱导速度比p53略慢，通过抑制细胞周期蛋白依赖的激酶活性和p53的不稳定来评估它们的功能。在E6/E7抑制后，p105(Rb)和p107也有戏剧性的转录后诱导，随后不久又诱导了p130。到感染后24小时，只有低磷酸化的p105(Rb)被检测到，几个Rb/E2F调节基因的转录被显著抑制。HPV16E6/E7基因的结构性表达减轻了E2诱导的生长抑制、Rb途径的激活和E2F反应基因的抑制。这一动态反应强烈表明，在HeLa细胞中，P53和RB肿瘤抑制通路是完整的，HPVE6和E7的抑制以有序的方式动员这些途径，向细胞传递生长抑制信号。值得注意的是，宫颈癌变背后的细胞周期机制的主要变化可以通过抑制内源性HPV癌基因来逆转。
Most cervical carcinomas express high-risk human papillomaviruses (HPVs) E6 and E7 proteins, which neutralize cellular tumor suppressor function. To determine the consequences of removing the E6 and E7 proteins from cervical cancer cells, we infected HeLa cells, a cervical carcinoma cell line that contains HPV18 DNA, with a recombinant virus that expresses the bovine papillomavirus E2 protein. Expression of the E2 protein resulted in rapid repression of HPV E6 and E7 expression, followed approximate to 12 h later by profound inhibition of cellular DNA synthesis. Shortly after E6/E7 repression, there was dramatic posttranscriptional induction of p53. Two p53-responsive genes, mdm2 and p21, were induced with slightly slower kinetics than p53 and appeared to be functional, as assessed by inhibition of cyclin-dependent kinase activity and p53 destabilization. There was also dramatic posttranscriptional induction of p105(Rb) and p107 after E6/E7 repression, followed shortly thereafter by induction of p130. By 24 h after infection, only hypophosphorylated p105(Rb) was detectable and transcription of several Rb/E2F-regulated genes was dramatically repressed. Constitutive expression of the HPV16 E6/E7 genes alleviated E2-induced growth inhibition and impaired activation of the Rb pathway and repression of E2F-responsive genes. This dynamic response strongly suggests that the p53 and Rb tumor suppressor pathways are intact in HeLa cells and that repression of HPV E6 and E7 mobilizes these pathways in an orderly fashion to deliver growth inhibitory signals to the cells. Strikingly, the major alterations in the cell cycle machinery underlying cervical carcinogenesis can be reversed by repression of the endogenous HPV oncogenes.