Effect of ARK5 on the anti-tumour activity of OSI-027 via regulation of epithelial-mesenchymal transition in pancreatic cancer.

Abstract

e15758 Background: Pancreatic cancer (PC) is one of the most common lethal malignancies,OSI-027, a selective inhibitor of mTOR, has anti-tumour activity in PC and is currently in phase II clinical trials. According to the results of our previous study, OSI-027 sensitivity varies across pancreatic cancer cell lines; however, the underlying mechanisms are unclear. Methods: In this study,We sought to investigate the regulatory mechanisms underlying OSI-027 resistance in PC under both in vitro and in vivo conditions. Results: We demonstrated that in PC, sensitivity to OSI-027 was negatively correlated with ARK5 expression, and ARK5 knockdown could enhance OSI-027 sensitivity. Further, the mechanistic experiments showed that ARK5 inhibition could reverse EMT induced by OSI-027. Suppression of EMT by Twist siRNA could sensitize pancreatic cancer cells to OSI-027, but the combination of Twist siRNA and ARK5 siRNA did not enhance the anti-tumour effect of OSI-027. Moreover, under hypoxia-induced EMT, the cancer cells were less sensitive to OSI-027, but ARK5 siRNA could block the EMT process. The in vivo experiments showed that the combination of ARK5 and Twist siRNAs could enhance the anti-tumour effect of OSI-027 and restrain OSI-027-induced EMT. Conclusions: The results indicate that ARK5 plays a role in the resistance of pancreatic cancer cells to OSI-027 by regulating EMT and lay the groundwork for future clinical studies.