Discovery of dimeric guaianolides with all carbon linkers as potential antihepatoma agents.

HCC is a major malignancy in humans, and the discovery of new anti-HCC agents is urgently needed. In this study, 25 dimeric guaianolides with all carbon linkers were designed and synthesized via a bis-Diels-Alder reaction. An evaluation of the inhibitory effects of these dimers on the proliferation of three hepatoma cell lines indicated that compound 17 was the most active dimer with IC50 values of 1.5 (HepG2), 1.1 (Huh-7), and 1.1 μM (SK-Hep-1), which were 4.7-, 5.5- and 8.0-fold more active than sorafenib, respectively. Bioinformatic analysis predicted CDC45 as a potential target of compound 17, which was confirmed by CETSA, DARTS, and SPR assays. Compound 17 exerted its antiproliferative effect in a CDC45-dependent manner as demonstrated in CDC45 knockdown and overexpression HCC cells, promoted CDC45 nuclear export, arrested the cell cycle at the G2/M phase, induced apoptosis, and inhibited the migration and invasion of Huh-7 and SK-Hep-1 cells. In vivo experiments showed that compound 17 at 30 and 60 mg/kg inhibited tumor weight up to 76 % and 84 % without causing toxicity to major organs or impairing liver and kidney function. This study suggested compound 17 as a potential antihepatoma therapeutic agent targeting CDC45.