Design, synthesis, and evaluation of 5-((4-(pyridin-3-yl)pyrimidin-2-yl)amino)-1H-indole-2-carboxamide derivatives as anti-HCC agents targeting Nur77.

Hepatocellular carcinoma (HCC) remains a major global health challenge, with limited treatment options for advanced-stage patients. The orphan nuclear receptor Nur77 has emerged as a promising therapeutic target in HCC. Leveraging a molecular hybridization strategy based on our previously reported Nur77 modulators (10g, 4-PQBH, and 8b), we have designed and synthesized three series of 1H-indole-2-carbohydrazide derivatives with the potential to act anti-HCC agents. Of these compounds, 12b exhibited potent anti-proliferative activity against HCC cell lines (HepG2, IC₅₀ = 0.51 ± 0.12 μM; HCCLM3, IC₅₀ = 2.07 ± 0.51 μM) and demonstrated a higher affinity for binding to Nur77 (K = 0.42 μM) than the positive control compound CSN-B (K= 0.78 μM). Mechanistic studies revealed that 12b stabilizes Nur77 by inhibiting its ubiquitin-proteasomal degradation, leading to Nur77-dependent apoptosis via the ASK1-JNK/p38 pathway. Significantly, 12b suppressed tumor growth in HCCLM3 xenograft models without causing any observable toxicity, highlighting its therapeutic potential. These findings validate Nur77 as a viable target and establish 12b as a promising anti-HCC agent for further development.