ABSTRACT
Objective: To detect the methylation status of SOX11 gene in normal cervix, cervical cancer tissues and cervical cancer cell lines so as to explore the relationship between methylation status and expression of SOX11 gene. Methods: DNA methylation status of SOX11 gene in normal cervical, cervical cancer tissues and cervical cancer cell lines was analyzed by bisulfite sequencing and TA cloning assay. The expression of SOX11 mRNA in cervical cancer tissues, cell lines and normal cervical was detected by RT-PCR. Results: The average methylation rate of SOX11 in cervical cancer tissues (81.07%) was significantly higher than that in normal cervical tissues (12.86%) (P<0.001). The methylation status of SOX11 in HeLa, SiHa, C33-A and CaSki cells was all hypermethylated with the methylation of 90.71%, 97.14%, 77.14% and 99.64%, respectively. The expression of SOX11 mRNA in cervical cancer tissues was significantly lower than that in normal cervixes (P<0.001). The SOX11 gene expression was significantly negatively correlated with its promoter hypermethylation (P<0.001, r=-0.808). After demethylation agent 5-azacytidine treatment, SOX11 mRNA expression in cervical cancer cell lines was significantly increased. Further analysis showed that HPV infection in cervical cancer might increase SOX11 promotor methylation. Conclusion: SOX11 gene in cervical cancer is silenced by the hypermethylation of DNA in the promoter region.
ABSTRACT
Objective The aim of this study was to investigate the methylation status of fragile histidine triad( FHIT) gene, human mutl homolog 1(hMLH1)gene,p16 gene,retinoic acid receptor beta( RAR-beta) gene,Reprimo gene and tissue inhibitor of metalloproteinase 3 ( Timp3) gene in gastric cancer and corresponding paracancerous tissues. Methods The methylation levels of FHIT,hMLH1,p16,RAR-beta,Reprimo and TIMP3 genes in 42 clinically resected gastric cancer specimens and 42 corresponding paracancerous tissues were detected by sodium bisulfite sequencing. Results The average methylation rates of the genes in gastric cancer and corresponding paracancerous tissues were:FHIT(1. 50% ,1. 36% ),hMLH1(4. 77% ,0. 48% ),p16(9. 63% ,10. 36% ), RAR-beta(4. 75% ,4. 17% ),Reprimo(9. 71% ,3. 76% )and TIMP3 genes(18. 34% ,14. 06% ). Compared with the paracancerous control group,the average methylation rate of Reprimo gene was only statistically different in gastric cancer patients(P=0. 00787). The difference in methylation rate of Reprimo gene promoter in gastric cancer patients with the degree of tissue differentiation was sta-tistically significant(P<0. 05). Conclusion There has methylation in the cytosine guanidine dinucleotide island of the Reprimo gene promoter region in gastric cancer. The high methylation rate of the Reprimo gene can be used as a potential biomarker for gastric cancer to detect the early stage of gastric cancer.
ABSTRACT
Objective To study the changes of mRNA and protein expressions of Kras gene in thymic lymphomas induced by ionizing radiation,and to detect the methylation of CpG islands in promoter region of Kras gene,then to investigate the mechanisms for the occurrence of radiation carcinogenesis.Methods The thymic lymphoma models of BALB/c mice were made by X-ray irradiation,then the total RNA was extracted,cDNA was synthesized and the total protein was extracted from both thymic lymphoma tissue and normal thymus tissue;the mRNA and protein expressions of Kras gene in thymic lymphoma tissue and normal thymus tissue were detected by RT-PCR and Western blotting method, and the methylation of CpG islands in promoter region of Kras gene was detected by bisulfite sequencing PCR. Results The mRNA expression level of Kras gene in thymic lymphoma tissue was significantly higher than that in normal thymus tissue(P<0.01).The protein expression level in thymic lymphoma tissue was about 1.41 times higher than that in normal thymus tissue;4 CpG sites were methylated detected by bisulfite sequencing PCR in normal thymus tissue, however, 1 CpG site was methylated in thymic lymphoma tissue,the CpG islands in promoter region of Kras gene were demethylation state in thymic lymphoma. Conclusion Ionizing radiation can cause the changes of mRNA and protein expression levels of Kras gene in thymic lymphoma tissue by demethylation state of Kras gene,eventually lead to the occurrence of tumor;it might be one of the mechanisms for the occurrence of radiation carcinogenesis.