Inoscavin A, a Pyrone Compound Isolated From a Sanghuangporus Vaninii Extract, Inhibits Colon Cancer Cell Growth and Induces Cell Apoptosis via the Hedgehog Signaling Pathway

Abstract Background : Sanghuangporus vaninii, a large precious medicinal fungus called Sanghuang in China, has significant antitumor activity. We previously reported that a Sanghuangporus vaninii extract could lead to apoptosis in HT-29 cells through the intrinsic apoptotic pathway. We further found that inoscavin A exhibited anti-colon cancer activity, but its specific mechanisms have not been fully elucidated. Methods : Inoscavin A was obtained from Sanghuangporus vaninii by the classic phytochemical separation technology. The male BALB/c nude mice were injected with HT-29 colon cancer cells as animal model. In order to observe the pathological changes of tumor section, the Hematoxylin-eosin(H&E) staining was applied in the histological analysis. Metabolomics was utilized for the investigation of the overall changes of serum metabolites in animal model, and the potential targets of inoscavin A were analyzed by Ingenuity Pathway Analysis (IPA). We further employed a Molecular docking approach to predict the degree of combination of inoscavin A and Smo. Then we further performed Western blotting and immunofluorescence analysis to investigate the expression of proteins involved in Hh-related pathways in tumor tissues. In addition, the colony formation assay, scratch-wound assay and Transwell migration and invasion assay were conducted to evaluate the anti-colon-cancer activity of inoscavin A. Concurrently, the mitochondrial membrane potential assay and TUNEL apoptosis assay were detected to demonstrate the effect of inoscavin A on promoting HT-29 cells apoptosis. Western blot experiments verified the anti-tumor effects of inoscavin A were modulated the protein expression of Shh, Ptch1, Smo and Gli1 in HT-29 cells. Results : We showed that inoscavin A, a pyrone compound isolated from the Sanghuangporus vaninii extract, exerted its antitumor activity in an HT-29 colon cancer cell xenograft mouse model. Subsequently, we first time prove that the antitumor effects of inoscavin A were related to the hedgehog (Hh) signaling pathway. Furthermore, we demonstrated that Smo, the core receptor of the Hh pathway, was critical for the induction of apoptosis of inoscavin A and that overexpression of this target could significantly rescue cell apoptosis induced by inoscavin A treatment. Conclusion : Thus, our studies first propose that the natural outgrowth inoscavin A exerted its anti-cancer effects by inhibiting Smo to suppress the activity of the Hh pathway though inhibiting cell proliferation and promoting apoptosis. These findings further indicate that inoscavin A will be expected to be a prospective remedical compound for the treatment of colon cancer.