Long Non-coding RNA LINC00628 Interacts Epigenetically with the LAMA3 Promoter and Contributes to Lung Adenocarcinoma

Long non-coding RNAs (lncRNAs) have emerged as key regulators of cellular progress in lung adenocarcinoma. In this study, to identify cancer-related lncRNAs and genes, we screened for those lncRNAs that were differentially expressed in lung adenocarcinoma, which revealed LINC00628 overexpression and low expression of laminin subunit alpha 3 (LAMA3). This was further validated in the cancerous tissues from patients diagnosed with lung adenocarcinoma. Thereafter, we explored the functional relevance of LINC00628 and LAMA3 in lung adenocarcinoma by analyzing the recruitment of DNA methyltransferase (DNMT) and the cellular processes of lung adenocarcinoma cells following treatments that induced LINC00628 overexpression or LINC00628 silencing or with 5-azacytidine (5-Aza, a DNMT inhibitor). The results showed that LINC00628 silencing decreased cell proliferation, migration, and invasion as well as the drug resistance of lung adenocarcinoma cells to vincristine (VCR). The results were opposite in the cells with LAMA3 demethylation induced by 5-Aza treatment. Further research indicated that LINC00628 recruited DNMT1, DNMT3A, and DNMT3B to promote the methylation of LAMA3 promoter, thereby decreasing its expression. Moreover, an in vivo experiment was performed in nude mice to assess the tumor growth ability and drug resistance of human lung adenocarcinoma cells. It was observed that LINC00628 silencing or 5-Aza treatment inhibited the in vivo tumor growth ability of the human lung adenocarcinoma cells and reduced their resistance to VCR. Altogether, our results provide evidence of a mechanism by which LINC00628 silencing exerts an inhibitory role in lung adenocarcinoma by modulating the DNA methylation of LAMA3, indicative of a novel molecular target for treatment of lung adenocarcinoma patients showing resistance to VCR.