The Mechanism Of Benzo(a)pyrene-induced Epithelial-mesenchymal Transition In Lung Adenocarcinoma A549 Cell

Objectives:To investigate whether benzo(a)pyrene(B[a]P), a tobacco procarcinogen, can promote the metastasis and proliferation of A549 human lung adenocarcinoma cell line by inducing epithelial mesenchymal transition(EMT); And to research the role of twist1, a transcription factor, in B[a]P-induced epithelial-mesenchymal transition.Methods:A549 human lung adenocarcinoma cell were exposed to benzo(a)pyrene (B[a]P,1μmol/L) for 4 weeks. As compared with undisposed group and DMSO group, changes of every index of EMT at different time point were observed. Including morphology under an inverted microscopy; The influence of B[a]P on migration of A549 was evaluated by transwell and wound-healing assay; Changes in expression of epithelial phenotypic markers including E-cadherin, expression of mesenchymal phenotypic markers including vimentin and N-cadherin, and twist1 were analysed by Western blot, and changes in mRNA levels assessed by RT-PCR. The cellular localization and expression of E-cadherin and vimentin was observed using laser scanning confocal microscope.The role of twist1 in B[a]P-induced EMT was investigated using pGCsilencerTM-twist1-shRNA. Consequent, to research the changes of EMT indexes mentioned above. The alteration in the cell proliferation and liposome cytotoxicity test were determined by MTT experiment.Results:The data showed that 1μmol/L B[a]P induced A549 human lung adenocarcinoma epithelium phenotype to undergo EMT. The process EMT was accompanied by morphological alteration partly and a downregulation of the epithelial phenotype marker E-cadherin, concomitant with a upregulation of mesenchymal phenotypic markers including vimentin, N-cadherin at mRNA and protein levels Moreover,twist1was also raised. And metastasis and proliferation were strengthened. After the twist1 was suppressed, cellular morphology and EMT markers were reversed to a certain extent, namely, the reversions are not full.Conclusion:Based on our research that tobacco procarcinogen, B[a]P can induce human lung adenocarcinoma A549 cells to undergo EMT, and enhance the metastasis and proliferation of A549 cells; The transcription factor Twist1 participates the process of the EMT induced by B[a]P, but is not associated with the proliferation of A549.