Synthesis of amide-linked panaxadiol-indolinedione derivatives: A novel NSD2/H3K36me2 epigenetic modulator with significant antitumor efficacy.

In this study, a series of novel C-3-amide-linked PD-indolinedione and PD-benzenesulfonamides derivatives were designed and synthesized. Among the newly synthesized PD derivatives, 5b exhibited broad-spectrum antiproliferative activity against five cancer cell lines (IC50 = 2.12-4.99 μM), demonstrating significantly superior potency to 5-fluorouracil (5-Fu) and the parent PD. Crucially, 5b showed exceptional tumor selectivity for HepG-2 cells, with a selectivity index (SI) of up to 9.06 compared to normal HaCaT cells, markedly exceeding that of 5-Fu (SI = 1.18). Molecular docking revealed that 5b competitively binds to the SAM pocket of NSD2 (ΔG = -11.0 kcal/mol) through hydrogen bonding and forms π-cation interactions with the key residue HIS A:1116. The Cellular Thermal Shift Assay (CETSA) further validated the effective binding of compound 5b to its target protein, NSD2, within HepG-2 cells. Mechanistic studies demonstrated potent suppression of NSD2 expression and its mediated H3K36me2 methylation. This inhibition reversed TWIST1-driven cadherin switching, thereby suppressing epithelial-mesenchymal transition (EMT). Furthermore, 5b induced G0/G1 cell cycle arrest and promoted apoptosis via mitochondrial pathway activation, characterized by reduced mitochondrial membrane potential (MMP) and subsequent ROS generation. In HepG-2 xenograft models, oral administration of 5b (40 mg/kg) achieved 79.6 % tumor growth inhibition-significantly outperforming 5-Fu (51.4 %)-without observable organ toxicity. ADME prediction and rat liver microsome assays demonstrated that 5b exhibits significantly enhanced metabolic stability and favorable drug-like properties. Overall, as the first PD-derived modulator of the NSD2/H3K36me2 epigenetic axis, 5b combines broad-spectrum antitumor activity, enhanced metabolic stability, potent in vivo efficacy, and an excellent safety profile, positioning it as a highly promising lead candidate.