Abstract 3603: A novel approach to enhance delivery and sensitivity of gemcitabine in pancreatic cancer by suppression of desmoplasia

Abstract

Background: Pancreatic ductal adenocarcinoma (PDAC) is an extremely fatal disease due to lack of efficient therapy and resistance to current standard therapy, gemcitabine (GEM). Numerous studies implicate the intimate reciprocal interactions due to paracrine Hedgehog (Hh) signaling between epithelia and underlying stroma that leads to desmoplasia and causes chemoresistance in PDAC. We report for the first time that a non-steroidal drug, ormeloxifene (ORM) has anticancer properties and depletes tumor-associated stromal tissue by inhibiting the Hh cellular signaling pathway in PDAC. This provoked us to investigate the combinatorial effects of ORM with GEM and we observed that ORM disrupts the stroma of pancreatic tumors, alters vascular network and thereby facilitates delivery and sensitivity of GEM. Methods: Using cell line models, Western blotting and QPCR were used to investigate the treatment effects of ORM, GEM and their combination on Hh signaling pathway and the related proteins involved in PDAC. To determine the effect of ORM on anti-tumorigenic sensitivity of GEM, we developed PDAC xenograft mice models using PanCa cells, BXPC3. Tumor tissue sections were stained for SHH (sonic hedgehog), cygb/STAP (stellate cell selective markers), α-SMA (PSC activation), FSP-1 (Fibroblast surface protein-1), collagen-1 by immunoflorescence, F4/80 (macrophage), CD31 (vasularization) through immunohistochemistry and microRNAs through in situ hybridization. ELIZA was performed for SDF1/CXCL12 and SHH secretion. Results: ORM inhibits cell proliferation and induces apoptosis in pancreatic cancer cells. ORM alone and in combination with GEM inhibits the Hh signaling pathway by downregulating both the protein and mRNA levels of SHH and its related important downstream targets: GLI1, PTCH1/2, NFκB, p-AKT and Cyclin D1. ORM potentiates the anti-tumorigenic effect of GEM by 75% in PDAC xenograft mice. Investigations of treated xenograft tumor tissues show that ORM depletes tumor-associated stromal tissue by inhibiting the Hh cellular signaling pathway and both mouse/human collagen-1, a hallmark of desmoplastic reaction. These xenograft tumors treated with ORM in combination with GEM also show the inhibition of oncogenic miR-21 and restoration of tumor suppressor, miR-132. The combination therapy inhibits stromal cell populations infiltrating into the tumor tissue and produces increased intratumoral vascular density and concentration of GEM, leading to transient stabilization of tumor growth. Tumor cells, co-cultivated with TGFβ stimulated human pancreatic stromal cells, displayed increased invasive capabilities which were inhibited on treatment with ORM alone or in combination with GEM. Conclusion: We propose that ORM has a high therapeutic index and represents a great promise for a combination therapy with GEM against stroma and neoplastic cells as a treatment of choice Citation Format: Sheema Khan, Mara Ebeling, A. Ansarullah, Neeraj Chauhan, Rishi Kumar Gara, Meena Jaggi, Haotian Zhao, Subhash C. Chauhan. A novel approach to enhance delivery and sensitivity of gemcitabine in pancreatic cancer by suppression of desmoplasia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3603. doi:10.1158/1538-7445.AM2014-3603