Hepatocellular Carcinoma Cells with Downregulated ZEB2 Become Resistant to Resveratrol by Concomitant Induction of ABCG2 Expression

In hepatocellular carcinoma (HCC), the presence of cancer stem cells (CSCs) have been linked to drug resistance, epithelial-mesenchymal transition (EMT), and cancer relapse. This study investigates the expression profile of ZEB1, ZEB2, ABCG2 in HCC-CSCs, and the role of EMT promoter ZEB2 in cells treated with resveratrol. The expression of ZEB1, ZEB2 and ABCG2 transcripts were analyzed in CD133(+)/CD44(+) cells isolated from the PLC/PRF/5 cell line. ZEB2-dependent ABCG2 gene expression and the effects of resveratrol on proliferation, cell cycle and apoptosis were explored in SNU398 cell clones. An inverse correlation between ZEB1/ZEB2 and ABCG2 levels were observed both in CSCs and in ZEB2-knockdown cells. The resveratrol treatment significantly decreased cell viability, while promoting cell cycle arrest in ZEB2-independent manner. Interestingly, resveratrol-treated cells with low levels of ZEB2 were resistant to apoptosis. The interplay of expression levels of ABCG2 and ZEB family EMT transcription factors may play a role in establishing CSC-like phenotype in HCC cells resistant to resveratrol.