Liang X H, Mungal S, Ayscue A, Meissner J D, Wodnicki P, Hockenbery D, Lockett S, Herman B
Laboratory for Cell Biology, School of Medicine, University of North Carolina at Chapel Hill 27599, USA.
J Cell Biochem. 1995 Mar;57(3):509-21. doi: 10.1002/jcb.240570316.
Bcl-2 protein expression has been found to block apoptosis and its overexpression has been implicated in lymphoid malignancies where the chromosomal translocation t(14;18) is present. In this study we investigated bcl-2 transcription and protein expression in cultured cervical carcinoma cell lines and keratinocytes. Western blotting and immunofluorescence microscopy demonstrated bcl-2 expression in the cytoplasm of 4 out of 5 cervical carcinoma cell lines examined (HeLa, CaSki, C-33A, and HT-3, but not SiHa). Bcl-2 protein expression was undetectable in normal keratinocytes. None of the cell lines examined demonstrated chromosomal translocation or rearrangement at the major breakpoint-cluster region (MBR) of the bcl-2 gene using either Southern blot or polymerase chain reaction (PCR) analyses. Northern blot analysis demonstrated low levels of bcl-2 transcription in HeLa, CaSki, and C-33A cell lines while reverse transcriptase (RT)-PCR demonstrated bcl-2 transcription in all cervical carcinoma cell lines which had bcl-2 protein expression. Thus, these data suggest that bcl-2 expression occurs in cervical carcinoma cell lines in the absence of chromosomal translocation or rearrangement of the bcl-2 gene. However, each of these cervical carcinoma cell lines contains inactive p53, either due to mutation (C-33A and HT-3) or via complexation and degradation with human papillomavirus (HPV) 16/18 E6 protein (HeLa and CaSki). Thus, functional p53, which can induce apoptosis in certain cells, is not present in these cervical cells which have increased bcl-2 expression. Increased bcl-2 expression under conditions of p53 inactivation may provide cells with a selective advantage for survival and consequently play a role in the development of cervical carcinogenesis.
已发现Bcl-2蛋白表达可阻断细胞凋亡，其过表达与存在染色体易位t(14;18)的淋巴系统恶性肿瘤有关。在本研究中，我们调查了培养的宫颈癌细胞系和角质形成细胞中bcl-2的转录及蛋白表达情况。蛋白质印迹法和免疫荧光显微镜检查显示，在所检测的5种宫颈癌细胞系（HeLa、CaSki、C-33A和HT-3，但不包括SiHa）中，有4种细胞系的细胞质中存在Bcl-2表达。在正常角质形成细胞中未检测到Bcl-2蛋白表达。使用Southern印迹法或聚合酶链反应（PCR）分析，在所检测的细胞系中均未发现bcl-2基因主要断裂点簇区域（MBR）存在染色体易位或重排。Northern印迹分析显示，HeLa、CaSki和C-33A细胞系中bcl-2转录水平较低，而逆转录酶（RT）-PCR显示，在所有有Bcl-2蛋白表达的宫颈癌细胞系中均有bcl-2转录。因此，这些数据表明，在不存在bcl-2基因染色体易位或重排的情况下，宫颈癌细胞系中会出现Bcl-2表达。然而，这些宫颈癌细胞系中的每一种都含有失活的p53，这要么是由于突变（C-33A和HT-3），要么是通过与人乳头瘤病毒（HPV）16/18 E6蛋白复合并降解（HeLa和CaSki）。因此，这些Bcl-2表达增加的宫颈细胞中不存在可在某些细胞中诱导凋亡的功能性p53。在p53失活的情况下，Bcl-2表达增加可能为细胞提供生存的选择性优势，从而在宫颈癌发生发展中发挥作用。
