Chili pepper leaves extract induced antitumor effect via inhibition of NFkB/METTL1 mediated glycolysis in hepatocellular carcinoma cells

Abstract In the current work, we investigated the antitumor effects of a 30% ethanol extract of chili pepper leaves ( Capsicum annum; PLE), in Hep3B and Huh7 hepatocellular carcinoma (HCC) cells. PLE showed significant cytotoxicity and reduced the expression of pro-caspase 3 and pro-poly (ADP-ribose) polymerase (pro-PARP) in Hep3B and Huh7 cells. Also, it also suppressed glycolysis-related proteins, including hexokinase 2 (HK2), pyruvate kinase M2 (PKM2), lactate dehydrogenase (LDH), methyltransferase-like 1 (METTL1), and NF-κB/IκB. Notably, PLE decreased METTL1 and NF-κB subunit RELA expression in both nuclear and cytosolic fractions in Hep3B and Huh7 cells. Furthermore, PLE disturbed the interaction between METTL1 and RELA, while RELA depletion reduced HK2 and LDH expression in Huh7 cells. In contrast, METTL1 depletion did not affect NF-κB phosphorylation, suggesting that METTL1 functions downstream of NFkB. In vivo, PLE treatment significantly inhibited Hep3B tumor growth in BALB/c nude mice without affecting body weight. Immunohistochemistry revealed decreased METTL1, NF-κB, LDH, and proliferating cell nuclear antigen (PCNA) expression, along with increased caspase-3 activation. Collectively, these findings suggest that PLE exerts anticancer effects by inducing apoptosis and suppressing NF-κB/METTL1-mediated glycolysis in HCC, supporting its potential as a dietary anticancer supplement. Graphical abstract