Cyclin G2: Expression and functional analysis of new cell cycle regulator in human oral cancer

我们已经证明，在激光捕获微切割中，人类细胞周期蛋白G2的表达下调。Western分析显示细胞周期蛋白G2在正常口腔角质形成细胞系中可检测到，但在恶性口腔角质形成细胞系中未检测到。对口腔粘膜、发育不良的口腔上皮和口腔癌上皮进行免疫组织化学分析。Cyclin G2在100%的正常口腔黏膜、69.1%的异型增生口腔黏膜上皮和11.1%的口腔癌上皮细胞核中表达。通过异位恢复Cyclin G2在人恶性鳞癌细胞系中的表达，体外功能研究发现细胞增殖和集落形成受到抑制，细胞周期中G1期细胞数增加，S期细胞数减少。在永生化的正常口腔角质形成细胞中，基于短干扰RNA的基因沉默稳定下调了Cyclin G2的表达，促进了细胞的生长，并使S细胞的生长速度增加，且细胞周期明显处于G2期。细胞周期蛋白G2被认为是细胞周期进程中的负调控因子。

We have shown that human cyclin G2 is down-regulated in laser capture microdissection using microarray. Western analysis showed detectable cyclin G2 protein in normal but not in malignant oral keratinocyte cell lines. Immunohistochemistry analysis done on oral mucosa, dysplastic oral epithelia and oral cancer epithelia. Cyclin G2 expressed in 100% of normal oral mucosa, 69.1% of dysplastic oral epithelia in the nuclei and 11.1% of oral cancer epithelia in the nuclei. In vitro functional study by ectopic restoration of Cyclin G2 expression in the human malignant squamous cell carcinoma line resulted in a inhibition of cellular proliferation and colony formation with increased population of G1 phase and decreased in S phase. Stable down-regulation of Cyclin G2 by short interference RNA-based gene silencing in immortalized normal oral keratinocytes resulted in enhanced cell growth with increase in S and prominently in G2 phase. Cyclin G2, has been implicated as a negative regulator in cell cycle progression.