The role of DAMPs in the activation of cancer-associated fibroblasts in primary and secondary liver cancer

• Applicant: Professor Dr. Ingmar Mederacke
• Subject Area: Gastroenterology
• Term: since 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 286076014

Liver cancer is the sixth most common cancer worldwide, and the fourth leading cause of cancer-related mortality. In addition, the liver represents one of the major metastatic sites for solid tumors including colorectal carcinoma, breast cancer and melanoma. Hepatic stellate cells (HSC) are the main fibrogenic cell type in the liver and the major source of cancer-associated fibroblasts (CAF) in primary and secondary liver cancer. Damage-associated molecular patterns (DAMPs) are metabolites that are released from damaged or dying cells triggering sterile inflammation in different organs including the liver. The effects of DAMPs on non-inflammatory cells in fibrosis and the tumor microenvironment are largely unexplored. We have recently identified the P2Y14 receptor being highly enriched in HSC and demonstrated that its ligands UDP-glucose, UDP-galactose und UDP-glucuronic acid are released upon hepatocyte death. P2Y14 inactivation resulted in reduction of liver fibrosis in several in vivo models. In this context, not only hepatocytes but also HCCs and liver metastasis contain the P2Y14 ligands UDP-glucose and UDP-galactose. Whether the P2Y14 DAMP receptor system also plays a role in the activation of CAF in the tumor microenvironment is unknown. In the current proposal we want to address the following aims. In Aim 1, we will investigate the role of P2Y14 and its ligands in the development and progression of primary liver cancer (hepatocellular carcinoma, HCC) using different well-established models of HCC (diethylnitrosamine, choline-deficient high fat diet, Mdr2 knockout) in P2ry14 wildtype and knockout mice. In Aim 2, we will study the contribution of P2Y14 to the activation of HSC-derived cancer-associated fibroblasts in the metastatic niche. We will induce liver metastasis using different tumor cell lines in P2ry14 wildtype and knockout animals and analyze tumor growth as well as P2Y14 ligands by mass spectrometry in the different metastasis models. In Aim 3, we want to validate the human relevance of the P2Y14 DAMP receptor system. Therefore, we will determine the density and distribution of CAF and the P2Y14 receptor in human primary and secondary liver cancer by immunohistochemistry and gene expression. Moreover, we want to determine levels of P2Y14 ligands in primary and secondary liver cancer and demonstrate the functional expression of P2Y14 on CAF isolated from primary and secondary liver cancer. Finally, we aim to analyze whether the expression of P2Y14 has an influence on the recurrence and outcome of secondary liver cancer after resection. The identification and functional validation of the P2Y14 DAMP system in primary and secondary liver cancer may provide the basis for novel therapies that specifically target the activation of cancer-associated fibroblasts within the tumor microenvironment.

• DFG Programme: Research Grants