Interaction of Alkannin with CPEB4 Contributes to Its Antitumor Effects in Melanoma

Melanoma is a highly aggressive malignancy characterized by strong invasive and metastatic potential. CPEB4 has been implicated in melanoma progression and may serve as a potential therapeutic target. Alkannin has previously been reported to exert antitumor activity against melanoma; however, its in vivo efficacy and direct molecular interaction with CPEB4 remain unclear. In this study, a subcutaneous xenograft model using BALB/c nude mice was used to assess the in vivo antitumor effects of alkannin, and CPEB4 expression was analyzed via Western blotting. DARTS, CETSA, and SPR investigations were used to elucidate the interaction between alkannin and CPEB4. In addition, stable CPEB4-knockdown A375 melanoma cells were established to examine the effects of alkannin on cell proliferation, apoptosis, cell cycle progression, migration, invasion, and downstream signaling molecules. Alkannin markedly suppressed tumor growth in the xenograft model and reduced CPEB4 expression in a dose-dependent manner compared with the model group. DARTS and CETSA demonstrated alkannin-induced stabilization of CPEB4, while SPR analysis using purified recombinant CPEB4 showed a direct physical interaction with alkannin, with micromolar affinity. At the molecular level, alkannin downregulated CPEB4 and PRC1 expression (p < 0.05), whereas CPEB4 knockdown markedly suppressed MITF and PRC1 (p < 0.05). Notably, alkannin treatment alone did not significantly alter MITF protein expression under the present experimental conditions. Alkannin exerts antitumor activity against melanoma, while its interaction with CPEB4 and the associated molecular changes may contribute to cellular responses involving proliferation, survival, migration, invasion-related phenotypes, and mitotic regulation.