The MK2/Hsp27 axis is a major survival mechanism for pancreatic ductal adenocarcinoma under genotoxic stress.
Patrick Grierson, Paarth B. Dodhiawala, Yi Cheng, Timothy Hung-Po Chen, Iftikhar Ali Khawar, Qing Wei, Daoxiang Zhang, Lin Li, John M. Herndon, Joseph B. Monahan, Marianna B. Ruzinova, Kian‐Huat Lim
Abstract
by RNA interference or by a small-molecule inhibitor enhanced apoptosis caused by FIRINOX in vitro. Mechanistically, FIRINOX up-regulated tumor necrosis factor–α (TNFα), causing autocrine phosphorylation and activation of transforming growth factor–β–activated kinase 1 (TAK1), MAPK activated protein kinase 2 (MAPKAPK2 or MK2), and, ultimately, Hsp27. Targeting MK2, the kinase that directly phosphorylates Hsp27, abrogated Hsp27 activation, sensitized PDAC cells to apoptosis, and suppressed SN-38–induced protective autophagy in vitro, in part by blocking phospho-activation of Beclin1. In an autochthonous PDAC mouse model, the MK2 inhibitor ATI-450 decreased PDAC development and progression. When combined with FIRINOX, ATI-450 eliminated most PDAC foci and marked prolonged mouse survival without causing additional toxicity. Last, we found that high phospho-MK2 expression in tumors was associated with poorer survival of patients with PDAC. Our study identified MK2 as a mediator of genotoxic stress–induced activation of prosurvival pathways and provides preclinical support for combining an MK2 inhibitor with FIRINOX-based chemotherapies to treat PDAC.