Piperlongumine potentiates the effects of gemcitabine in in vitro and in vivo human pancreatic cancer models

// Jiyan Mohammad 1 , Harsharan Dhillon 1 , Shireen Chikara 1 , Sujan Mamidi 2 , Avinash Sreedasyam 2 , Kishore Chittem 3 , Megan Orr 4 , John C. Wilkinson 5 and Katie M. Reindl 1 1 Department of Biological Sciences, North Dakota State University, Fargo, ND 51808, USA 2 Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA 3 Department of Plant Pathology, North Dakota State University, Fargo, ND 51808, USA 4 Department of Statistics, North Dakota State University, Fargo, ND 51808, USA 5 Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 51808, USA Correspondence to: Katie M. Reindl, email: katie.reindl@ndsu.edu Keywords: apoptosis; cell cycle regulation; complementary and alternative therapy; reactive oxygen species; RNA-Seq Received: September 13, 2017     Accepted: December 15, 2017     Published: December 23, 2017 ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers due to a late diagnosis and poor response to available treatments. There is a need to identify complementary treatment strategies that will enhance the efficacy and reduce the toxicity of currently used therapeutic approaches. We investigated the ability of a known ROS inducer, piperlongumine (PL), to complement the modest anti-cancer effects of the approved chemotherapeutic agent gemcitabine (GEM) in PDAC cells in vitro and in vivo . PDAC cells treated with PL + GEM showed reduced cell viability, clonogenic survival, and growth on Matrigel compared to control and individually-treated cells. Nude mice bearing orthotopically implanted MIA PaCa-2 cells treated with both PL (5 mg/kg) and GEM (25 mg/kg) had significantly lower tumor weight and volume compared to control and single agent-treated mice. RNA sequencing (RNA-Seq) revealed that PL + GEM resulted in significant changes in p53-responsive genes that play a role in cell death, cell cycle, oxidative stress, and DNA repair pathways. Cell culture assays confirmed PL + GEM results in elevated ROS levels, arrests the cell cycle in the G0/G1 phase, and induces PDAC cell death. We propose a mechanism for the complementary anti-tumor effects of PL and GEM in PDAC cells through elevation of ROS and transcription of cell cycle arrest and cell death-associated genes. Collectively, our results suggest that PL has potential to be combined with GEM to more effectively treat PDAC.