A calcium-sensing MCTP1/FYN/MEF2C circuit drives therapy-induced neuroendocrine prostate cancer

Neuroendocrine prostate cancer (NEPC) represents a highly aggressive, treatment‑refractory phenotype that frequently emerges after androgen‑deprivation therapy (ADT). Although perturbed calcium signaling has been implicated in prostate cancer bone metastasis, the specific molecular mechanisms governing NEPC progression remain incompletely characterized. Here, we delineate the MCTP1/FYN/MEF2C signaling axis as a pivotal modulator of intracellular calcium homeostasis that drives neuroendocrine differentiation (NED) and enhances tumor aggressiveness. We demonstrate that ADT upregulates MCTP1, a transmembrane protein with calcium-sensing capabilities, which subsequently activates the Src-family kinase FYN to initiate oncogenic signaling cascades. This activation induces transcriptional upregulation of bone morphogenesis-related genes, including MEF2C and ALPL. Mechanistically, calcium-responsive transcription factors ZEB1 and ZEB2 directly transactivate MEF2C, thereby integrating calcium flux with epithelial-to-mesenchymal transition (EMT) programs in prostate cancer. Elevated ZEB1/ZEB2-dependent MEF2C expression reinforces the MCTP1/FYN kinase pathway, potentiating neuroendocrine lineage commitment and ALPL enzymatic activity. Chromatin immunoprecipitation coupled with transcriptomic analyses reveals that MEF2C directly occupies regulatory elements of MCTP1, FYN, and ALPL, enabling their calcium-dependent transcriptional activation. Structure-based virtual screening identified a potent small-molecule antagonist targeting MCTP1, which markedly attenuates tumor burden, ALPL activity, and neuroendocrine marker expression in prostate cancer in vitro and in vivo models. Collectively, these findings establish MCTP1 as a novel therapeutically exploitable vulnerability in therapy-induced NEPC, providing critical insights into the calcium-dependent oncogenic signaling networks mediated by the MCTP1/FYN/MEF2C axis in advanced prostate cancer.