AASLD Washington DC October 2017:
Prasanna K. Santhekadur, Divya P. Kumar, Kalyani Daita, Mulugeta Seneshaw, Faridoddin Mirshahi, Arun J. Sanyal;
Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University, Richmond, VA
BACKGROUND. Natriuretic peptide receptor-C (NPR-C) clears circulating natriuretic peptides e. g. ANP by binding and internalization. ANP is decreased and NPR-C expression is increased in obesity a risk factor for NAFLD. In several cell types, NPR-C increases cell proliferation and inflammation which are known oncogenic signals HYPOTHESIS: NPR-C expression is increased in NAFLD and related HCC and can drive oncogenesis by increased cell proliferation and oncogenic signaling AIMS: To define: (1) if NPR-C is overexpressed in human NAFLD and associated HCC, (2) the effects of high-fat diet on NPR-C expression, upstream regulators of NPR-C and its relationship to NAFLD phenotype and HCC in the diet-induced animal model of NAFLD (DIAMOND) which recapitulates the key elements of human disease, (3) the effects of ANP-binding to NPR-C on oncogenesis-related secretome, and (4) the oncogenic potential of NPR-C and its associated mechanisms. METHODS: NPR-C expression in normal, NASH and HCC in humans and DIAMOND mice was determined by qPCR and Western blot. Circulating [ANP] was measured by ELISA in normal, NAFL, NASH and HCC in both humans and mice. The effects of ANP ligation of NPR-C on secreted proteins was measured in HepG2 cells using angiogenesis and cytokine arrays. The oncogenic potential of NPR-C was tested by its effects on cell proliferation, migration, invasion and anchorage-independent growth in QGY-7703 cells. Pathway analysis from array studies was used to identify potential signaling pathways. The role of these were assessed the impact of inhibitors on NPR-C mediated oncogenic properties. RESULTS: NPR-C expression increased progressively from control to NAFL to NASH to HCC in both humans and in the DIAMOND mice. This was associated with lower circulating ANP in both humans (Normal vs NASH, p< 0.05) and in DIAMOND (CD vs WD, p< 0.05) mice. ANP ligation of NPR-C revealed SMAD/TAZ as key transcriptional factors related to its effects on the secretome. High fat diet led to a progressive increase in NPR-C expression in DIAMOND mice along with increased SMAD/TAZ expression which was greatest in NASH and HCC. Loss of function of NPR-C with siRNA in QGY-7703 HCC cells resulted in suppressed proliferation, migration, invasion and anchorage independent growth and down- regulated SMAD/TAZ protein expression. Inhibition of SMAD/TAZ pathway with PKA activators (forskolin and 8-bromo-cAMP) inhibited cell proliferation in these cells. CONCLUSION: Obesity and NAFLD increases hepatic NPR-C expression. NPR-C activation may contribute to HCC formation in NASH by its pro-oncogenic properties mediated by activation of SMAD/TAZ transcriptional factor.
Arun J. Sanyal – Advisory Committees or Review Panels: Bristol Myers, Gilead, Genfit, Abbott, Ikaria, Pfizer, Novartis, Virology Education, Intercept, Sanofi; Consulting: Salix, Immuron, Exha lenz, Nimbus, Genentech, Echosens, Takeda, Merck, Enanta, Zafgen, JD Pharma, Islet Sciences, ardelyx; Grant/Research Support: Salix, Genentech, Intercept, Ikaria, Takeda, GalMed, Novartis, Gilead, Tobira; Independent Contractor: UpToDate, Elsevier; Management Position: Sanyal Biotechnology; Stock Shareholder: Exhalenz, Hemoshear, Akarna, tiziana, Genfit
The following people have nothing to disclose: Prasanna K Santhekadur, Divya P. Kumar, Mulugeta Seneshaw, Faridoddin Mirshahi