Cardol exposure induces cytotoxic and transcriptional changes consistent with CDK2 inhibition in Hep-G2 cells

Abstract

Abstract Cardol (5-[8(Z), 11(Z)-pentadecadienyl] resorcinol) is a long chain phenolic lipid with reported antitumor properties, but its molecular targets and mechanisms of growth inhibition against hepatocellular carcinoma cells remain unclear. This study aimed to elucidate its cytostatic mechanism and molecular targets in Hep-G2 hepatocellular carcinoma cells. Cytotoxicity was assessed by MTT assay, revealing an IC50 value of 24.56 ± 0.31 µM, and morphological examination revealed cell rounding, shrinkage, and detachment indicative of stress induced death. Gene expression analysis by RT-qPCR after 48 h treatment with cardol at its IC50 value demonstrated significant upregulation of p21 accompanied by downregulation of Cyclin E, Cyclin A, and replication licensing genes (CDC6, MCM2, PCNA), indicative of checkpoint activation and G1/S transition arrest. Molecular docking across 35 cancer-related proteins identified CDK2 (ΔGbind = -7.84 kcal/mol; Ki ≈ 1.8 µM) and MEK1 (ΔGbind = -7.66 kcal/mol; Ki ≈ 2 µM) as high-affinity targets, with interaction residues overlapping those of reference inhibitors roscovitine and refametinib, respectively. Inhibition of CDK2 explains the G1/S arrest and repression of replication factors, whereas MEK1 inhibition suppressed ERK signaling and was likely associated with compensatory upregulation of STAT3, AKT, and c-MYC as part of a survival feedback loop. Consequently, these findings suggest that cardol acts as a multitarget modulator that suppresses proliferation through coordinated inhibition of CDK2-RB-E2F and MEK-ERK signaling, leading to cytostatic arrest that progresses toward cytotoxicity.