胃癌细胞周期不同时相MTS1/p16、p21、p53的表达

Differential transcription of p16, Wafi/p21 and p53 genes through the cell cycle in human gastric carcinoma cell lines

目的：进一步明确不同周期时相肿瘤细胞p16基因的表达水平及在细胞周期调控中的作用。方法：改进并建立了一个高同步率、高收获率的细胞周期同步化的方法[7]，通过此方法把细胞同步在不同的时期，对RNA及蛋白的表达进行研究，确定在不同周期时相中p16的表达有何变化，同时分析其它几个重要的抑癌基因如p53、p21，研究它们在细胞周期中的表达以及与p16基因相互关系。结果：确定在不同周期时相的胃癌细胞系MGc80－3和BGC823细胞中，p16mRNA的表达随细胞种类的不同而有一定的差异，其蛋白在各周期时相中均有表达，在两种细胞中无明显差异。p53在各个周期时相的表达无明显差异，Wafl／p21的蛋白和mRNA的表达具有一致性，M期其mRMA不表达，而蛋白有微弱的表达。结论：以上结果表明在肿瘤细胞G1期CDK4活性的调节，可能主要不是发生在mRNA和蛋白表达水平上。

Objective: To determine the expression of p16, Wafl /p21 and p53 genes in G1, S, G2/M phase of human gastric tumor cell lines, MGC803 and BAC82－3. Methods: The cells were synchronized in G1, S, G2/M phase by using high pressure N2O technique. Northern, Western blotting and immunofluorescence techniques was used to detect gene expression . Results: High efficient synchronizated cells were obtained and expreession of p16. Wafi/p21 and p53 genes were detected in the cells. Neither p16 mRNA nor its protein expression is changed during cell cycle progression of the MGC80－3. In BGC823 cell there is no detectable expression of p16 mRNA in M and G1 phase while p16 protein is constitutively expressed through the cell cycle. Similar with foe expression of p16 mRNA, p53 mRNA expression is not Changed by cell cycle progression in the two cell lines. although its exprexxion level in MGC80－3 is much higher in M phase than G1, S and G2 phases. Expression of p21 mRNA was detected in G1, S and G2 phases, but not in M phase, and the expression of p21 protein is lower in M phase than G1 . S and G2 phases. Our also show that p16 and p21 protein in G1 and S phase was located in cytoplasm and gathered to nucleus in G2 phase. Conclusion These results suggested that the regulation of CDK4 activity in G1 phase of human gastric. tumor cells may not rely on the edpression of mRNA and protein.