Targeting integrin alpha5 receptor in pancreatic stellate cells to diminish tumor-promoting effects in pancreatic cancer

Pancreatic stellate cells (PSCs) are the main precursors of cancer-associated fibroblasts (CAFs) in pancreatic ductal adenocarcinoma (PDAC), known to induce cancer aggressiveness. Integrin alpha5 (ITGA5), a fibronectin receptor, was found to be overexpressed by CAFs in stroma and linked to poor overall survival (log-rank p=0.022, n=137) of patients with PDAC. In vitro, knockdown of ITGA5 in human PSCs (hPSCs) inhibited their adhesion, migration, and proliferation and also inhibited TGF-{beta}-mediated differentiation. In vivo, co-injection of PANC-1 tumor cells and hPSCs (sh-ITGA5) developed tumors with reduced fibrosis and slower growth rate compared to those composed of PANC-1 and hPSC (sh-Ctrl). Furthermore, we developed a ITGA5-antagonizing peptidomimetic (AV3) which inhibited TGF{beta}-mediated hPSC differentiation by blocking ITGA5/FAK pathway. In vivo, treatment with AV3 intraperitoneally attenuated tumor fibrosis and thereby enhanced the efficacy of gemcitabine in patient-derived xenografts in mice. Altogether, this study reports the therapeutic importance of ITGA5 in PDAC and provides novel therapeutic peptidomimetic to enhance the effect of chemotherapy.