Histone deacetylase inhibitors provoke a tumor supportive phenotype in pancreatic cancer associated fibroblasts
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Andrew H. Nguyen1, Irmina A. Elliott1, Nanping Wu1, Cynthia Matsumura1, Maria Vogelauer2, Narsis Attar2, Amanda Dann1, Razmik Ghukasyan1, Paul A. Toste1, Sanjeet G. Patel1, Jennifer L. Williams3, Luyi Li1, David W. Dawson4, Caius Radu5, Siavash K. Kurdistani2, Timothy R. Donahue1,5
1Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
2Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
3Department of Surgery, Harbor-UCLA Medical Center, Torrance, California, USA
4Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
5Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
Timothy R. Donahue, email: [email protected]
Keywords: histone deacetylase inhibitor, SAHA, AP-1, pancreatic cancer, cancer-associated fibroblasts
Received: October 04, 2016 Accepted: November 07, 2016 Published: November 24, 2016
Although histone deacetylase inhibitors (HDACi) are a promising class of anti-cancer drugs, thus far, they have been unsuccessful in early phase clinical trials for pancreatic ductal adenocarcinoma (PDAC). One potential reason for their poor efficacy is the tumor stroma, where cancer-associated fibroblasts (CAFs) are a prominent cell type and a source of resistance to cancer therapies. Here, we demonstrate that stromal fibroblasts contribute to the poor efficacy of HDACi’s in PDAC. HDACi-treated fibroblasts show increased biological aggressiveness and are characterized by increased secretion of pro-inflammatory tumor-supportive cytokines and chemokines. We find that HDAC2 binds to the enhancer and promoter regions of pro-inflammatory genes specifically in CAFs and in silico analysis identified AP-1 to be the most frequently associated transcription factor bound in these regions. Pharmacologic inhibition of pathways upstream of AP-1 suppresses the HDACi-induced inflammatory gene expression and tumor-supportive responses in fibroblasts. Our findings demonstrate that the combination of HDACi’s with chemical inhibitors of the AP-1 signaling pathway attenuate the inflammatory phenotype of fibroblasts and may improve the efficacy of HDACi in PDAC and, potentially, in other solid tumors rich in stroma.
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