The Expression Of CCNG2 In Thyroid Papillary Cancer And Its Effect On Proliferation And Apoptosis To The K1 Cells

Objective: The cell cycle protein G2(Cyclin G2 CCNG2) is a member of the cell cycle protein family that found lately. The recent study found that CCNG2 has the inhibition of cell proliferation, promote apoptosis, and the role of negative regulation of tumor cell development. Our study aim to explore the CCNG2 gene expression in K1 cell line of thyroid papillary carcinoma(PTC), then investigated the impact on proliferation, apoptosis of the K1 cells. In this study we try to explore the mechanism of promoting apoptosis of tumor.Methods:1 Transfection thyroid papillary carcinoma K1 cells in vitro by the CCNG2 gene over expression plasmid p EGFP- N1- CCNG2 that optimized transfection conditions.2 MTT assay and flow cytometry(FCM) were used to observe the biological of the K1 cells. Western blot and Immunohistochemistry were used to detect the protein expression of CCNG2, p53, mdm2 in K1 cells.3 Statistical analysis. SPSS17.0 statistical software was used for statistical analysis.Quantitative data were presented as mean±SD. The single-factor analysis of variance(One-way ANOVA) was used to campare multiple samples. A P-value of <0.05 was considered as statistically significant.Results:1 The result of transfection,when the ratio between DNA and Lipo2000 was 1:5, the tranfection sfficiency was the highest(77.33±3.79)%(P<0.05);when the fusion degree of cells were 50-60% the tranfection sfficiency was the highest(90.33±1.53)%(P<0.05).2 MTT assay indicated that transfection CCNG2 gene K1 cells performance significant cell growth inhibition than nontransfection and negative transfection(P<0.05), the growth inhibition rate was 35.40% at 72 h after tranfection.3 Flow cytometry(FCM) analysis showed that, both the early and late apoptosis rate of p EGFP-N1-CCNG2 group was obviously higher than the two control groups[early:(5.48±0.35)%vs(1.06±0.05)%,(1.12±0.09)%;late:(9.90±0.94)%vs(2.65±0.20)%,(1.58±0.28)%](P<0.05). There were no statistical difference between blank control groups and negative control groups(P<0.05).4 Western blot analysis showed that CCNG2 protein level of transfection CCNG2 gene K1 cells significant higher than nontransfection and negative transfection(0.72±0.053 vs 0.36±0.032, 0.37±0.040)(P<0.05). There was no statistical difference between nontransfection and negative transfection groups(P>0.05). The expression levels of p53 and mdm2 proteins were up-regualted following the level improve of CCNG2 in transfection CCNG2 gene K1 cells.5 Immunohistochemistry result show that The expression levels of p53 and mdm2 proteins were up-regualted following the level improve of CCNG2 in transfection CCNG2 gene K1 cells.Conclusions:1 The CCNG2 possess a role of inhibit proliferation, promote apoptosis in transfection CCNG2 gene PTC K1 cell line.2 After transfection CCNG2 gene in K1 cells, the level of CCNG2 and p53 protein expression were up-regualted. The role of promote apoptosis may be associated with CCNG2 gene induced p53 protein expression.3 The expreesion level of mdm2 protein was up-regualted in transfection CCNG2 gene K1 cells, Speculated that this phenomenon due to the high level of p53 protein. The reason CCNG2 induced mdm2 protein expression need further study to elucidate.