Influence of IP-10/CXCL10 induction in human pancreatic cancer stroma on lymphocytes recruitment and correlation with survival.

Abstract

290 Background: Pancreatic ductal adenocarcinoma is characterized by an abundant desmoplastic reaction driven by pancreatic stellate cells (PSCs) that contributes to tumor progression. Here we sought to characterize the interactions between pancreatic cancer cells (PCCs) and PSCs that affect the inflammatory and immune response in pancreatic tumors. Methods: Conditioned media from mono- and cocultures of PSCs and PCCs were assayed for expression of cytokines, chemokines and growth factors. Gene expression analysis of human pancreatic ductal adenocarcinoma samples was used to verify expression of cytokines and their correlation with markers of immunoresponse and with clinical outcome. Finally, we tested chemotaxis of leukocytes isolated from peripheral blood mononuclear cells of pancreatic cancer patients. Results: IP-10/CXCL10 was the most highly induced chemokine in coculture of PSCs and PCCs. Its expression was induced in the PSCs by PCCs. IP-10 expression was consistently upregulated in human pancreatic cancer specimens, and positively correlated with high stroma content. Furthermore, expression of IP-10 and its receptor CXCR3 were significantly associated with the intratumoral presence of regulatory T cells (Tregs). In an independent cohort of 48 patients with resectable pancreatic ductal adenocarcinoma, the survival of patients with high IP-10 levels was 18.1 months less than those with low IP-10 levels (HR=2.14, 95% CI 1.05 -4.42). Importantly, IP-10 stimulated the ex vivo recruitment of CXCR3+ effector T cells as well as CXCR3+ Tregs derived from patients with pancreatic cancer. Conclusions: Our findings suggest that, in pancreatic cancer patients, CXCR3+ Tregs are recruited by IP-10 expressed by PSCs in the tumor stroma, leading to immunosuppressive and tumor-promoting effects.