High expression of MEG3 can regulate the level of histone H3 methylation by recruiting the histone methyltransferase EZH2 and the histone demethylation enzyme JARID2 to the regulatory regions of the epithelial marker gene CDH1 and microRNA-200 family genes, which play a key role in the EMT process mediated by TGF-beta, which ultimately results in lung cancer and regulates EMT in lung cancer at the epigenetic level. The gene discussed is PRDM9; the disease is lung carcinoma.