Expression of DNMT1 and the methylation status of hMLH1 and hMSH2 in non-small-cell lung cancer

LIU Jun; SUN Yu; WANG Yanning; LIU Wenzhou; ZHOU Huafu

doi:10.3969/j.issn.1002-266X.2017.41.006

Abstract：Objective To investigate the DNA methyltransferase 1 (DNMT1)expression and the changes in the methylation status of hMLH1 and hMSH2 genes in the tumor tissues and adjacent tissue specimens of non-small-cell lung cancer (NSCLC). Methods The expression of DNMT1 in 52 lung cancer specimens and adjacent tissue specimens was detected by real-time fluorescent quantitative PCR (FQ-PCR). Meanwhile,promoter methylation status of hMLH1 and hM-SH2 was detected by methylation-specific PCR (MSP). Correlation of DNMT1 expression with methylation of hMLH1 and hMSH2 genes was analyzed by Spearman correlation analysis. Results The expression of DNMT1 mRNA in 52 cases of NSCLC specimens and adjacent tissue specimens was 3. 1623 ± 0. 5125 and 2. 8731 ± 0. 3706 (P < 0. 001). The posi-tive rate of promoter methylation of hMLH1 in the lung cancer specimens was higher than that in the adjacent tissue speci-mens [53. 8%(28 / 52)vs. 32. 7% (17 / 52),χ2 = 4. 740,P < 0. 05]. The positive rate of promoter methylation of hM-SH2 in the cancer specimens was higher than that in the adjacent tissue specimens [57. 7%(30 / 52)vs. 34. 6%(18 / 52),χ2 = 5. 571,P < 0. 05]. Methylation status of hMLH1 and hMSH2 was not correlated with the patients'gender,age,tumor size,pathological types,lymph node metastasis,and invasion of surrounding tissues (all P > 0. 05). The expression of DNMT1 was positively correlated with the methylation level of hMLH1 and hMSH2 (r = 0. 479,0. 528,all P < 0. 05). Conclusion DNMT1 is highly expressed in the NSCLC tissues and the DNMT1expression is positively correlated with the promoter methylation levels of hMLH1 and hMSH2 genes,and the expression of these three parameters is not correlated with the clinicopathological features of NSCLC.