Abstract: Objective To investigate the methylation status of GATA4 in non-small cell lung cancer(NSCLC), and its effect on NSCLC cells and possible mechanism. Methods Cancer tissues and paracancerous tissues, as well as human lung cancer cell lines A549, HCC827, NCI-H1299 and human normal lung epithelial cells BEAS-2B, of 78 patients with NSCLC who received radical surgery of lung cancer in First Affiliated Hospital of Xinjiang Medical University from July 2017 to June 2018 were collected. The methylation status of GATA4 gene was detected by MSP and qMSP, the expression of GATA4 was detected by RT-PCR and Western blot. The sh-GATA4-1(SH-GATA4 group), sh-NC, GATA4 overexpression vector(pLV-GATA4 group) and empty vector control lentiviral vector(pLV-NC group) were transfected into lung cancer A549 cells, respectively, and a blank control group(Blank group) was set up. The protein expressions of GATA4, p-ERK, ERK, p-p38 and p38 were detected by Western blot; cell viability was detected by CCK-8; cell proliferation was detected by cell clone formation assay; cell apoptosis was detected by flow cytometry. Results The methylation rate of GATA4 gene, expression levels of p-ERK, p-p38 and Bcl-2 proteins in NSCLC tissues were higher than those in paracancerous tissues(P<0.001), while the expression of GATA4 mRNA, GATA4  and Bax proteins were lower(P＜0.001). The methylation level of GATA4 gene was positively correlated with the expression of p-ERK, p-p38 and Bcl-2 proteins(P<0.05), and negatively correlated with the expression of GATA4 mRNA, GATA4 and Bax proteins(P<0.05). GATA4 was in a methylated state in NSCLC cells, while human normal lung epithelial cells BEAS-2B was in a demethylated state, and the GATA4 mRNA and protein expressions were lower than those of BEAS-2B cells(P<0.01). Compared with the pLV-NC group, the GATA4 mRNA and protein expression and apoptosis rate were increased in pLV-GATA4 group(P<0.001), while the cell viability, cell clone number, p-ERK/ERK and p-p38/p38 protein expression were decreased(P<0.05); GATA4 mRNA and protein expression and cell apoptosis rate in sh-GATA4 group were lower than those in sh-NC group(P<0.001), while cell viability, cell clone number, p-ERK/ERK and p-p38/p38 protein expression were higher(P<0.05). Conclusion GATA4 gene is hypermethylated in non-small cell lung cancer and in-duces a decrease in GATA4 gene expression. Overexpression of GATA4 may inhibit the proliferation and induce apoptosis of lung cancer cells by regulating MAPK pathway.

Key words: Non-small cell lung cancer, GATA4, Methylation, MAPK pathway