Abstract A21: Chemokine directed migration of activated stellate cells in pancreatic ductal adenocarcinoma

Abstract

Abstract Multiple studies have shown that the extreme desmoplasia observed in pancreatic tumors modulates the effectiveness of chemotherapeutic agents. Despite this, the specific mechanisms by which stroma develops in pancreatic tumors are unknown and the role that it plays in pathogenesis of the disease is unsettled. Chemokines are a family of nearly 50 different secreted proteins playing a key role in the recruitment of a wide variety of cell types in health and disease. While we and others have extensively explored the role of the chemokine CXCL12 in pancreatic cancer, the expression and potential role of other chemokines, or their cognate receptors, in pancreatic cancer remains an area of active exploration. To this end, we profiled the expression of the chemokine family in pancreatic cancer. RT-PCR of a battery of established human pancreatic cancer cell lines revealed elevated transcript levels of the chemokine ligands CCL28 and CXCL16, as well as their cognate receptors CCR10 and CXCR6, respectively. These results were mirrored in cell lines derived from transgenic murine models of pancreatic cancer. Immunohistochemical analysis of both diseased and normal human pancreatic tissue showed that the expression of CCL28, CXCL16, CCR10, and CXCR6 proteins were upregulated in pancreatic adenocarcinoma compared with normal exocrine ductal epithelium. Interestingly, CCR10 and CXCR6 were also expressed in pancreatic tumor fibroblasts, while their cognate ligands, CCL28 and CXCL16 were absent in the stromal compartment. Based on those data we hypothesized that expression of chemokines in cancer cells with the concomitant expression of their cognate receptors by activated fibroblasts facilitates recruitment of those cancer-associated fibroblasts into the tumor microenvironment. Analysis of tissue from patients with pancreatitis revealed that CCL28/CCR10, but not CXCL16/CXCR6, proteins were upregulated. Consistent with its known regulation by inflammatory mediators, we found that interferon-gamma stimulated significant increases in CCL28 secretion by human pancreatic cancer cell lines. In contrast, interferon-gamma had little if any effect on CCL28 secretion by an immortalized activated human pancreatic stellate cell (HPSC) line. Stimulation with exogenous CCL28 elicited the prototypical dose dependent calcium signaling expected of a ligand activated chemokine receptor. CCL28 stimulated the dose dependent directional migration of HPSC without altering cell viability. These data are consistent with HPSC being a functional target for the chemokine. Finally, in a 2-D co-culture model, CCL28 secreted from human pancreatic cancer cells induced HPSC chemotactic migration. Pretreatment with neutralizing antibody to the chemokine blocked HPSC chemotaxis toward the cancer cells. Together, these data suggest that the CCL28-CCR10 chemokine axis plays a role in the inflammation-mediated recruitment of cancer-associated fibroblasts into the stromal compartment of pancreatic tumors. More broadly, we have demonstrated a new role for chemokines in the pancreatic tumor microenvironment, suggestive of their potential role in stromal remodeling in pancreatic cancer. This is the first study to establish the differential expression and functional role for the CCL28 chemokine in pancreatic disease. Citation Format: Ishan Roy, Kathleen A. Boyle, A Craig Mackinnon, Rosa F. Hwang, Susan Tsai, Douglas B. Evans, Michael B. Dwinell.{Authors}. Chemokine directed migration of activated stellate cells in pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr A21.