Therapeutic targeting RORγ with natural product N-hydroxyapiosporamide for small cell lung cancer by reprogramming neuroendocrine fate.

Small cell lung cancer (SCLC) is an aggressive and exceptionally fatal disease. Unlike non- small cell lung cancer (NSCLC), no targetable genetic driver events have been identified in SCLC to date. Here, we investigate the function of RAR-related orphan receptor gamma (RORγ) and identified the anti-cancer activity of its natural inhibitor against SCLC and illustrate the underlying mechanism. We show that RORγ depletion affected cell growth both in 2-D cell proliferation and 3-D organoids formation. Natural marine product N -hydroxyapiosporamide (N -hydap) directly bound to RORγ and inhibited its transcriptional activity, leading to the blocking of transmission process of RORγ signaling. Gene expression profiling analysis revealed that N -hydap reprograms neuroendocrine fate via inhibiting RORγ activity in SCLC. Chromatin immunoprecipitation analysis showed that N -hydap strongly reduced RORγ occupancy and transcriptional activation-linked histone marks H3K27ac on the promoter and/or enhancer sites of neurogenesis markers gene including aurora kinase a (AURKA), delta like canonical Notch ligand 3 (DLL3) and tubulin beta 3 class III (TUBB3). Therapeutically, N -hydap exhibited a strong inhibitory effect on tumor growth and did not show significant toxicity in SCLC mice xenograft models. Taken together, RORγ could be an attractive target for SCLC and thus N -hydap can be a promising therapeutic drug candidate for SCLC by inhibiting the RORγ activation. [Display omitted] • RORγ represents a potential therapeutic target in SCLC. • Natural product N -hydap was identified as a novel and potent RORγ inhibitor. • RORγ reprograms neuroendocrine fate of SCLC cells both in vitro and in vivo. • N -hydap can be a promising therapeutic drug candidate for SCLC. [ABSTRACT FROM AUTHOR]