The role of miR-506 in transformed 16HBE cells induced by anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide

Growing evidence indicates that the alteration of microRNA (miRNA) expression in tumors that is induced by chemical carcinogens plays an important role in tumor development and progression. However, the mechanism underlying miRNA involvement in lung carcinogenesis induced by anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide (anti-BPDE) remains unclear. In our study, we used the malignant transformation of human bronchial epithelial cells (16HBE-T) induced by anti-BPDE to explore the mechanisms of human lung carcinogenesis. We found that expression of miR-506 was reduced in 16HBE-T transformed malignant human bronchial epithelial cells compared with 16HBE normal human bronchial epithelial cells. Restoration of miR-506 in 16HBE-T cells led to a decrease in cell proliferation, G0/G1 phase cell cycle arrest, as well as significantly suppressed anchorage-dependent growth in vitro and tumor growth inhibition in a nude mouse xenograft model. In addition, we provided novel evidence regarding the role miR-506 potentially plays in negatively regulating the protein and mRNA expression level of N-Ras in cancer cells. Together, these findings revealed that miR-506 acts as an anti-oncogenic miRNA (anti-oncomir) in malignantly transformed cells. The identification of tumor suppressive miRNAs could provide new insight into the molecular mechanisms of chemical carcinogenesis.

• miR-506 exhibits a low level of expression in transformed human bronchial epithelial cells (16HBE-T) induced by anti-BPDE. • Restoration of miR-506 by transfection of microRNA mimics in 16HBE-T cells induces growth suppression and decreases the degree of malignancy. • miR-506 acts as an anti-oncogenic miRNA in malignantly transformed cells. • N-Ras is a putative target of miR-506.