ABSTRACT
Objective@#To study effects of cyclin D1 overexpression on the proliferation and differentiation of cervical squamous cell carcinoma SiHa cells and to investigate related signaling molecules.@*Methods@#Primers were designed to amplify the full length of cyclin D1 gene and cyclin D1 gene was amplified by PCR for constructing pcDNA3.1 plasmid vector. The construct was then transfected into SiHa cells, and the cells with stable overexpression of cyclin D1 were established, cyclin D1 gene and protein expression were detected by RT-PCR and Western blot, respectively. Cell growth curve was documented by MTT assay. CK7, E-cadherin, vimentin, Snail gene and protein expression in transfected cells were detected by RT-PCR and Western blot. RT-PCR was used to detect the mRNA expression of proliferation and differentiation-related genes like CDK4, CDK2, p21, p27, cyclin E, Rb, E2F, E6/E7 and Ki-67. After synchronization of cells, RT-PCR was used to detect of cyclin D1 and p21 mRNA expression at different time points of the cell cycle.@*Results@#The G-3 cells with cyclin D1 overexpression were successfully established. The growth curve and Ki-67 mRNA expression accelerated in G-3 cells.Vimentin and Snail expression significantly increased at both gene and protein levels, while E-cadherin, CK7 gene and protein expression significantly decreased, indicating epithelial mesenchymal transitionoccurred in G-3 cells.Meanwhile, mRNA expression of cyclin D1, CDK4, CDK2, p21, p27, cyclin E, E2F and Rb increased, while E6/E7 and p16 showed no significant change. The expression trends of p21 and cyclin D1 were almost identical with fluctuation at different time points in the cell cycle.@*Conclusions@#Overexpression of cyclin D1 induced by gene transfection promotes proliferation and epithelial mesenchymal transition in SiHa cells.The process is accompanied by up-regulation of CDK4, CDK2, p21, p27 and cyclin E genes.p21 expression increases synchronously with cyclin D1, suggesting a regulatory role in epithelial mesenchymal transition by affecting expression of vimentin in G-3 cells.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression of cyclin D1 in cervical intraepithelial neoplasia (CIN) and squamous cell carcinoma and its relationship with human papillomavirus 16 (HPV16) E7 gene expression.</p><p><b>METHODS</b>Both SiHa and Hcc94 cell lines were obtained from cervical epithelial cells of squamous cell carcinoma. E6/E7 gene was silent in Hcc94 cell line.Expression levels of cyclin D1 mRNA and protein in CIN and squamous cell carcinoma were detected by QT-PCR and immunohistochemistry (IHC) respectively. SiRNA was constructed for targeting the promoter of HPV16 E7 and then transfected into SiHa cells to establish cm-16 line with stable silencing of E7. Control cell line B3 was obtained by blank plasmid transfection into SiHa cells. RT-PCR and Western blot were used to detect cyclin D1 mRNA and protein expression in the SiHa, B3, and cm-16 cells, respectively.</p><p><b>RESULTS</b>Cyclin D1 was expressed in the basal cells of normal cervical squamous epithelia and the expression gradually decreased in the progression from CIN1 to CIN3. Squamous cell carcinoma showed negative or scattered expression of cyclin D1 (P<0.05). Both mRNA and protein of cyclin D1 in E7(+) SiHa cells were lower than those in cm-16 and Hcc94 cells.</p><p><b>CONCLUSION</b>Squamous cell carcinoma with high HPV E7 expression shows low level of cyclin D1, suggesting that HPV16 E7 gene inhibits the expression of cyclin D1.</p>