Abstract 4021: Assessing the sensitivity of LSF inhibitors against liver cancer

Abstract

Introduction: Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the second leading cause of cancer mortality. The transcription factor Late SV40 Factor (LSF) functions as an oncogene in HCC, making it a potential protein target for HCC therapy. LSF overexpression correlates with pathogenesis of liver, colorectal and pancreatic cancers, for which there are limited molecularly targeted therapy options. A library of dihydroquinolinones, termed Factor Quinolinone Inhibitors (FQIs), inhibits LSF-DNA binding and specific LSF-protein interactions in in vitro and in cellular assays. The initial lead compound FQI1 causes dramatic mitotic defects in HCC cell lines but has no toxic consequences on immortalized human hepatocytes or primary mouse hepatocytes. Additionally, FQI1 has proven efficacious in endogenous HCC mouse models, with no evidence of associated toxicity. Methods: A series of dihydroquinolinone compounds were synthesized and tested for potency in two HCC cell lines, Huh7 and SNU423, by a cell proliferation assay. The FQI analogs, FQI34, N-oxide FQI34 and FQI37, were separated by chiral chromatography to the corresponding R and S enantiomers. Direct target engagement of the three lead compounds, FQI1, FQI34 and FQI37, is shown with cellular thermal stability assays on Huh7 cells. Results: More than 20 compounds were synthesized and characterized. Among them, FQI37 showed the most potent activity (GI50 = 70 nM) against Huh7 HCC cells. Structure-activity-relationship studies suggest that the amide portion of quinolinone core is important for optimal activity. Growth inhibition assays revealed enantiomeric specificity; the (S)-enantiomers are more potent than the (R)-compounds and the racemate. The cellular thermal shift assay in Huh7 cells demonstrated the direct target binding of FQIs to LSF in cells at micromolar concentrations. Growth inhibition assays also identified colorectal cancer and pancreatic cancer lines to be sensitive to the dihydroquinolinones treatment. Conclusions: Aryl-dihydroquinolinones are promising small molecule chemotherapies for LSF-driven cancers such as HCC, colorectal cancer, and pancreatic cancer. Citation Format: Niranjana Pokharel, John Kavouris, Jessica Biagi, Ulla Hansen, Scott E. Schaus. Assessing the sensitivity of LSF inhibitors against liver cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4021.