Background: Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death worldwide. It is a heterogeneous disorder and >80 % of the tumors develop in patients with liver cirrhosis, resulting from chronic inflammation and/or fibrosis. Here, we set out to identify novel targets for HCC therapy and to define a subgroup of patients that might benefit most from it.
Methods: Cellular pathway activation profiling of 45 transcription factors in a HCC-derived cell line (HEP3B), in vitro analysis of NFκB reporter activity in additional HCC-derived cell lines and pathway-focused integrative analyses of publicly available primary HCC-derived expression profiling data (GSE6764, GSE9843, E-TABM-36 and E-TABM-292) were employed to reveal a role of NFκB in HCC development. In order to identify potential targeting agents, a luciferase-based NFκB reporter screening assay was established in HEP3B cells. After screening of a drug library through this assay, a potent NFκB pathway inhibitor was identified and characterized using an array of additional in vitro assays.
Results: Using cellular pathway activation profiling, we found a high activation of NFκB-mediated signaling in HCC-derived cell lines and in primary HCC tumors. Through NFκB inhibitor screening we observed a highly efficacious NFκB pathway inhibitory potential of ornithogalum in HCC-derived HEP3B cells. Although its active component still remains to be defined, ornithogalum has been found to inhibit endoplasmic reticulum (ER) and oxidative stress responses. ER stress, oxidative stress and NFκB signaling were found to be enhanced in a subset of HCCs, as well as in (precancerous) liver cirrhosis tissues.
Conclusion: From our data we conclude that NFκB signaling is activated in precancerous cirrhosis tissues and in a subset of HCCs. We found that ornithogalum exhibits NFκB targeting and stress relieving activities. NFκB inhibitors, including the active component of ornithogalum, may serve as putative preventive and targeted therapeutic agents for at least a subset of HCCs in which the NFκB pathway is activated. These latter notions require further investigation in a translational context.
Keywords: Anti-inflammatory; ER stress; Hepatocellular carcinoma; NFkB pathway; Ornithogalum; Oxidative stress; Targeted therapy.