Choline kinase inhibitors synergize with TRAIL in the treatment of colorectal tumors and overcomes TRAIL resistance

Aim: The aim of this study was to investigate the effects of the combination of choline kinase inhibitor MN58b and tumor necrosis factor-related apoptosis inducing ligand (TRAIL) against colon cancer cells.\nMethods: TRAIL-sensitive (DLD-1) and TRAIL-resistant (SW620) cells were treated with MN58b and/or TRAIL. Cell viability and induction of apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide and flow cytometry. Posttreatment expression levels of different proteins (PARP, caspase-3, X-linked inhibitor of apoptosis protein [XIAP], CHOP, DR5, DR4, CHOP) were analyzed by quantitative reverse transcription polymerase chain reaction, Western blot, and flow cytometry.In vivo antitumoral activity was assessed by xenograft models.\nResults: A strong synergistic effect of TRAIL and MN58b was observed in both TRAIL-sensitive and resistant cells. The combinatory treatment induced an increase in PARP and active-caspase 3 fragments along with a decrease in XIAP, enhancing TRAIL sensitivity. Reduced cellular viability and increased cell death correlated with increased DR5 expression and membrane surface recruitment, an effect that was concomitant with CHOP expression.\nConclusion: MN58b, which alone exhibits anticancer activities against a wide variety of tumor-derived cell lines, synergizes with TRAIL through a mechanism that involves DR5 upregulation. This study supports the use of MN58b in combination with TRAIL on colorectal tumors, including those that develop TRAIL resistance.