β-Carboline and N-hydroxycinnamamide hybrids as anticancer agents for drug-resistant hepatocellular carcinoma

In an effort to develop anticancer agents that may overcome drug resistance, the number one reason in caner death, we have developed a series of novel hybrids of β-carboline and N-hydroxycinnamamide as histone deacetylase (HDAC) inhibitors. Most of the hybrids 13a-p showed strong antiproliferative effects with low-micromolar IC₅₀ values against four human cancer cells. The most potent compound of series 13p exhibited high HDAC1/6 inhibitory effects, and also increased the acetylation levels of histone H3, H4 and α-tubulin. Importantly, 13p demonstrated high anticancer potency against drug-sensitive HepG2 and Bel7402 cells and drug-resistant Bel7402/5FU cells. Hybrid 13p triggered significant apoptosis by regulating apoptotic relative proteins expression in these Bel7402/5FU cells. Finally, 13p induced a substantial amount of autophagic flux activity by the accretion of the expression of LC3-II and the degeneration of expression of p62 and LC3-I in Bel7402/5FU cells. Overall, 13p is a novel β-carboline/N-hydroxycinnamamide hybrid with significant anticancer potency that warrants further evaluation for the treatment of drug-resistant hepatocellular carcinoma.