Ginsenoside Rh2 Suppresses the Fanconi Anemia Pathway by Inhibiting NF-κB-Mediated FANCL Transcription in Bladder Cancer.

Objectives: Cisplatin, a frontline chemotherapeutic agent for bladder cancer (BC), induces DNA interstrand crosslinks that are primarily repaired through the Fanconi anemia (FA) pathway. Hyperactivation of this repair mechanism contributes to cisplatin resistance, underscoring the need for FA-targeted sensitizers. This study investigated the effect of ginsenoside Rh2 on FA signaling and cisplatin sensitivity in bladder cancer cells. Methods: Bladder cancer cell lines (T24, 5637, and RT4) were treated with cisplatin, with or without Rh2 pretreatment. FANCI/FANCD2 (ID2) complex monoubiquitination, FANCD2 foci formation, and interactions with downstream repair proteins (FANCP, FANCQ, PCNA) were examined. FANCL expression was analyzed at the transcriptional level, and rescue experiments were performed by FANCL overexpression. NF-κB signaling involvement was assessed using pharmacological agonists. A T24 xenograft model was used to validate in vivo efficacy. Results: Cisplatin induced ID2 complex monoubiquitination, confirming FA pathway activation. Rh2 pretreatment abolished this modification and reduced FANCD2 foci formation, leading to persistent interstrand crosslinks without affecting intrastrand repair. Rh2 disrupted FANCD2- FANCP/FANCQ/PCNA interactions and selectively suppressed FANCL transcription. Overexpression of FANCL restored ID2 monoubiquitination despite Rh2 exposure. NF-κB agonists reversed Rh2-induced FANCL downregulation and FA inhibition. In vivo, Rh2 combined with cisplatin significantly reduced tumor growth in T24 xenografts, whereas NF-κB stimulation counteracted this effect. Conclusion: Ginsenoside Rh2 suppresses NF-κB signaling to transcriptionally downregulate FANCL, thereby impairing FA pathway-mediated DNA repair and enhancing cisplatin cytotoxicity in bladder cancer. These findings highlight Rh2 as a potential combinatorial agent to overcome platinum resistance.