Background: MicroRNAs (miRNAs) are small non-coding RNAs, involved in pathological and physiological processes via regulating target genes expression. Abnormally expressed miR-30a-3p has been verified in several tumors, such as liver cancer, esophageal cancer and lung cancer. It was reported that DNA methylation plays a critical role in the tumorigenesis of lung cancer through regulated tumor suppressor genes silencing. Nevertheless, the potential mechanism of miR-30a-3p in restoring abnormal DNA methylation patterns is still unclear in lung cancer. Therefore, because the miR-30a-3p is complementary to the 3ʹ-untranslated regions (3ʹ-UTR) of DNA methyltransferase 3A (DNMT3A), we investigated whether miRNA-30a-3p could target DNMT3a to regulate the progression of lung cancer cell.
Methods: qRT-PCR was used to evaluate miR-30a-3p and DNMT3a mRNA expression levels in A549 lung cancer cells and normal cell line BEAS-2B. MiR-30a-3p expression plasmid was transferred into A549 cells. The target of miR-30a-3p was detected by luciferase reporter assay. Western blot was used to measure related protein expression levels. MTT assay was used to measure the proliferation of cells in each group. The cycle and apoptosis of cells were detected by flow cytometry.
Results: We found down-regulation of miR-30a-3p mRNA expression and up-regulation of DNMT3a mRNA expression in A549 cells. Overexpression of miR-30a-3p downregulates DNMT3a or blocked DNMT3a by interference vector, significantly inhibited the proliferation and G1/S transition in A549 cells via regulating p38 MAPK pathway, and induced the apoptosis in A549 cells via regulating Bcl-2/Bax protein levels. Furthermore, we observed the opposite phenomenon in A549 cells transfected with both miR-30a-3p and DNMT3a vector.
Conclusion: Our data show that miR-30a-3p suppressed the progression of lung cancer via regulating p38 MAPK pathway by targeting DNMT3A in A549 cells, indicating that miR-30a-3p might be a novel potential therapeutic strategy in the treatment of lung cancer.
Keywords: DNA methylation, MiR-30a-3p, lung cancer, DNA methyltransferases, tumor suppressor genes