Transcriptomic and functional analysis ofANGPTL4overexpression in pancreatic cancer nominates targets that reverse chemoresistance

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers based on five-year survival rates. Understanding chemoresistance allows development of new treatment strategies to improve patient outcomes. High levels of ANGPTL4 in tumors correlate with poor outcomes in pancreatic cancer. We show that ANGPTL4 overexpression leads to in vitro resistance to gemcitabine and reduced survival times in patients. Overexpression of ANGPTL4 induces transcriptional signatures of tumor invasion and metastasis, proliferation and differentiation, and inhibition of apoptosis. To better understand how ANGPTL4 contributes to resistance and explore whether it might be a useful therapeutic target, we measured transcriptional response of cells with ANGPTL4 overexpression or knockdown. We also measured effects of gemcitabine treatment on these cells. These analyses revealed an overlapping signature of genes associated with both ANGPTL4 activation and gemcitabine response. Increased expression of the genes in this signature in patient PDAC tissues was significantly associated with shorter patient survival. We identified 42 genes that were both co-regulated with ANGPTL4 and were responsive to gemcitabine treatment. ITGB4 and APOL1 were among these genes. Knockdown of both genes in cell lines overexpressing ANGPTL4 reversed the observed gemcitabine resistance and inhibited cellular migration associated with epithelial to mesenchymal transition (EMT) and ANGPTL4 overexpression. These data suggest that ANGPTL4 promotes EMT and regulates the genes APOL1 and ITGB4. Importantly we show that inhibition of both targets reverses chemoresistance and decreases migratory potential. Our findings have revealed a novel pathway regulating tumor response to treatment and suggest relevant therapeutic targets in pancreatic cancer.