Use of PG545, a heparanase inhibitor, to inhibit pancreatic cancer tumor cell proliferation and migration in vitro and in vivo.

Abstract

234 Background: Pancreatic Ductal Adenocarcinoma (PDAC) is highly resistant to conventional chemotherapy, as result there is an ongoing search to find novel effective strategies. Resistance is due in part to the high proportion of stromal tissue within the primary tumor. This intricate ECM (extracellular matrix) includes heparan-sulfate glycosaminoglycans which participate in tumor progression, angiogenesis and metastasis. PG545 is a heparanase inhibitor developed to target these pathways. Methods: In vitro cell viability assays were performed using WST-1 reagent and migration was evaluated using T- scratch assay. Animal survival experiments were performed by intraperitoneal injection of AsPC-1 (0.75 x 10^6) cells. In vivo tumor growth experiments were performed by orthotopic injection of PanO2-HY (5x10^5) cells. Results: PG545 significantly inhibited proliferation of tumor cells (AsPC-1 and PanO2) and fibroblasts (WI-38). PG545 caused only a modest inhibition in endothelial cell (HUVECs) proliferation. Migration was significantly inhibited by 1 µM PG545 in AsPC-1 and PanO2 after 12 hours. In a metastatic model of pancreatic cancer, treatment with PG545 (10 mg/kg 1st week, 5 mg/kg 2nd week) improved survival (35 days) compared to saline (22 days) and gemcitabine (28 days). In an immunocompetent orthotopic model, mice treated with PG545 (5 mg/kg twice weekly) had significantly decreased tumor weights after 3 weeks of therapy (p=0.002). Total metastatic events were also reduced in PG545 compared to gemcitabine and control treatment in the PanO2 model. Conclusions: PG545 inhibits tumor cell proliferation and migration in vitro and prolongs survival and inhibits tumor growth in vivo. Additionally it inhibits metastasis in vivo. Further studies are underway to elucidate the mechanism of inhibition and changes to pancreatic tumor microenvironment.