[Differentially expression p21 and p53 in laryngeal squamous cell carcinoma]

AbstractObjective:To investigate the role of the methylation of p21 and p53 gene in laryngeal cancer and laryngeal cancer cell line Hep-2.Method: Methylation of p21 and p53 gene were detected by methylation specific PCR(MSP) in 46 cases with paired cancer tissues and adjacent tissues. Hep-2 cell line was treated with 5-azacytidine at different time points, and Hep-2 cell growth was detected using the MTT assay. Hep-2 cell line was treated with 5-azacytidine at different time points, and then apoptosis was detected by the TUNEL assay. The expression difference of p21 mRNA was detected by RT-PCR method before and after intervention. p21 promoter CpG island methylation status was tested by MSP before and after intervention.Result: The incidence was 45.7% of p21 gene promoter CpG island methylation in 46 cases of laryngeal cancer, while methylation rate in adjacent tissues was 10.9%. There were significant differences between cancer tissues and adjacent tissues(P<0.05).The incidence was 6.5% of p53 gene promoter CpG island methylation in 46 cases of laryngeal cancer, while methylation rate was 4.3% in adjacent tissues,no significant difference of p53 gene methylation was found in laryngeal cancer and counterparts adjacent tissues(P>0.05). The effect of Hep-2 proliferation inhibition interfered by 5-azacytidine was gradually increased over time in a time-dependent manner. Meanwhile, interfered by 5-azacytidine increased the apoptosis in a time-dependent manner. After interference by 5-azacytidine, p21 gene is activated. The expression of p21 mRNA was significantly higher. The p21 gene methylation degree in laryngeal cancer cell line Hep-2 was 43.13%±0.79%. After 5-azacytidine intervention, the degree of methylation was obviously decreased and even showed unmethylation.Conclusion:There was p21 gene promoter CpG island hypermethylation in laryngeal cancer and laryngeal cancer cell line Hep-2, which was a molecular event distinguished laryngeal cancer from normal laryngeal tissue. There was p53 gene promoter CpG island hypomethylation in laryngeal cancer and laryngeal cancer cell line Hep-2.Inactivation of the gene may occur by gene mutation forms and others. Demethylation of drug 5-azacytidine can induce p21 gene promoter CpG island demethylation modification, change the regulation of tumor cell cycle genes in cells and promote tumor cell apoptosis.