Establishment and Characteristics of a Novel Mantle Cell Lymphoma-derived Cell Line and a Bendamustine-resistant Subline.

Background/Aim: Bendamustine hydrochloride (BH) is a key therapeutic agent for mantle cell lymphoma (MCL), while the mechanism underlying BH-resistance has not been verified. Materials and Methods: We compared molecular/biological characteristics of a newly-generated MCL-derived cell line KPUM-YY1 and its BH-resistant subline KPUM-YY1R. Results: The growth-inhibitory IC50 for BH was 20 mu M in KPUM-YY1 cells, while cell proliferation was not inhibited by up to 60 mu M BH in KPUM-YY1R cells. Compared to KPUM-YY1 cells, gene expression profiling in KPUM-YY1R cells revealed upregulation of 312 genes, including ABCB1 encoding P-glycoprotein (P-gp), and microsomal glutathione S-transferase 1 (MGST1). Addition of either a P-gp inhibitor or a GST inhibitor, at least partly, restored sensitivity to BH in KPUM-YY1R cells. In addition, KPUM-YY1R cells showed cross-resistance against various anti-MCL chemotherapeutics. Conclusion: BH resistance is mediated by overlapping mechanisms with overexpression of ABCB1 and MGST1, and is potentially accompanied by multidrug resistance in MCL.