Aldehyde dehydrogenase 1A1 up-regulates stem cell markers in benzo[a]pyrene-induced malignant transformation of BEAS-2B cells

Recently, Aldehyde dehydrogenase 1A1 (ALDH1A1) has been proposed to be a common marker of cancer stem cells and can be induced by benzo[a]pyrene (B[a]P) exposure. However, the underlying mechanism of how ALDH1A1 contributes to B[a]P-induced carcinogenesis in human bronchial epithelial cells remains unclear. Here, we found that B[a]P up-regulated expression levels of stem cell markers (ABCG2, SOX2, c-Myc and Klf4), epithelial-mesenchymal transition (EMT) associated genes (SNAIL1, ZEB1, TWIST and β-CATENIN) and cancer-related long non-coding RNAs (lncRNAs; HOTAIR and MALAT-1) in malignant B[a]P-transformed human bronchial epithelial cells (BEAS-2B-T cells), and these up-regulations were dependent on increased expression of ALDH1A1. The inhibition of endogenous ALDH1A1 expression down-regulated expression levels of stem cell markers and reversed the malignant phenotype as well as reduced the chemoresistance of BEAS-2B-T cells. In contrast, the overexpression of ALDH1A1 in BEAS-2B cells increased the expression of stem cell markers, facilitated cell transformation, promoted migratory ability and enhanced the drug resistance of BEAS-2B cells. Overall, our data indicates that ALDH1A1 promotes a stemness phenotype and plays a critical role in the BEAS-2B cell malignant transformation induced by B[a]P.