Ganoderma immunomodulatory protein and chidamide down-regulate integrin-related signaling pathway result in migration inhibition and apoptosis induction

Background: In terms of melanoma, recent advances have been made in target therapies and immune checkpoint inhibitors, but durable remission is rare. Ganoderma immunomodulatory proteins (GMI) induce a cytotoxic effect in cancer cells via autophagy. However, the role of GMI in melanoma is not clear. Purpose: The aims of this study are to investigate the inhibiting effects of GMI combined with chidamide on survival and metastases of melanoma cells via integrin-related signaling pathway and to propose strategies for combining GMI and chidamide using animal model. Methods: Cell viability was measured by cell CCK-8. The activities of apoptosis-and migration-related proteins were detected on Western blot. Flow cytometry was used to analyze cell cycle distribution and sub-G1 fraction in treated melanoma cells. To evaluate the activity of combination GMI and chidamide treatment, an in vivo antitumor metastasis study was performed. Results: GMI combined with chidamide additively induced apoptosis. GMI inhibited the expressions of Integrin alpha 5, alpha V, beta 1, and beta 3. The level of p-FAK was inhibited by GMI. Combination treatment of GMI and chidamide decreased survivin and increased cleaved caspase-7 and LC3 II/I. Integrin-alpha V overexpression activated p-FAK pathways in A375.S2 cells. GMI significantly inhibited cell growth and migration of A375.S2 cells on wound healing assay. In vivo, GMI combined with chidamide suppressed distal tumor metastasis. Conclusion: GMI inhibits the migration and growth of melanoma cells via integrin-related signaling pathway. GMI and chidamide induces apoptosis. In vivo, GMI and chidamide additively reduce distant metastases. GMI and chidamide are potential immunotherapeutic adjuvant for metastatic melanoma.