Abstract 5514: Loss of hepatocyte growth factor activator inhibitor type-1 (HAI-1) in human lung adenocarcinomas promotes RON receptor phosphorylation and increased sensitivity to crizotinib

Abstract

Abstract Introduction: Non-small cell lung cancer (NSCLC) is the top cause of cancer-related mortality. We have identified a role for the tumor suppressor hepatocyte growth factor activator inhibitor type-1 (HAI-1) in human lung adenocarcinoma. HAI-1 loss results in unregulated downstream MET/RON tyrosine kinase receptor signaling. We hypothesized that HAI-1 is lost in human lung adenocarcinomas and could serve as a biomarker for therapy with crizotinib, a tyrosine kinase inhibitor (TKI) with activity against both MET and RON. We also hypothesized that unregulated RON signaling in the tumor microenvironment, via HAI-1 loss, may promote tumor metastasis by skewing tumor associated macrophages (TAMs) from an anti-tumor (M1) to a pro-tumor (M2) phenotype. Methods: Immunohistochemical staining with HAI-1 antibody (1N7) was performed on human tissue microarray containing 20 normal and 20 lung tumor specimens. Intensity grading (0, 1+, 2+, 3+) was performed, and percent cell expression was calculated for each group. For all in vitro assays, H358 lung adenocarcinoma cells, which express high levels of endogenous HAI-1, were stably transfected with mock shRNA or HAI-1 shRNA. Cell protein expression and phosphorylation was assessed via western blot. Cell viability after exposure to crizotinib was assessed by trypan blue staining. For flow cytometric analysis of macrophage phenotype, undifferentiated (M0) macrophages were exposed to conditioned medium from transfected H358 cells and macrophage phenotype was assessed by flow for surface markers CD68 (M0), CCR7 (M1), and CD206 (M2). Results: HAI-1 expression is significantly decreased in human lung adenocarcinoma compared to normal lung with overall HAI-1 IHC positivity ~20% compared to ~60% respectively. HAI-1 knockdown in H358 cells caused increased phosphorylation of RON and increased sensitivity to crizotinib. Culturing M0 macrophages in conditioned media from H358 shHAI-1 knockdown cells caused a decrease in the CCR7 positive M1 fraction from 8.4% to 1.9%, and an increase in the CD206 positive M2 fraction from 0.77% to 2.09%. Conclusion: We have demonstrated that loss of HAI-1 occurs in human lung adenocarcinoma consistent with previous studies in human NSCLC cell lines. Furthermore, we showed significantly increased RON signaling activity after HAI-1 knockdown. We have also demonstrated that HAI-1 loss can skew tumor associated macrophages (TAMs) from an anti-tumor (M1) to a pro-tumor (M2) phenotype. We have shown that loss of HAI-1 in vitro can increase sensitivity to crizotinib, suggesting that loss of HAI-1 may predict for tumor sensitivity to MET/RON inhibition. Our findings show that dysregulation of the HAI-1/MET/RON pathway exerts effects both on lung tumor cells as well as TAMs, making this pathway a potentially powerful therapeutic target. Citation Format: Austin J. McHenry, Gautam Sondarva, Vijayalakshmi Ananthanarayanan, Ashley Hess, Patricia E. Simms, Alhareth Alsayed, Hiroaki Kataoka, Jan Marusarz, Sandeep Kumar, Ravi Salgia, Arkadiusz Dudek, Stanley Borowicz, Ajay Rana. Loss of hepatocyte growth factor activator inhibitor type-1 (HAI-1) in human lung adenocarcinomas promotes RON receptor phosphorylation and increased sensitivity to crizotinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5514.