前列腺癌（PCa）是美国男性中最常诊断出的癌症，也是导致癌症死亡的第二大原因。雄激素剥夺疗法（ADT）已作为前列腺癌患者的一线治疗得到系统应用。尽管最初有反应，但大多数接受 ADT 的患者最终经历了肿瘤进展为去势抵抗性前列腺癌 (CRPC)，进一步导致肿瘤转移到远处器官。因此，确定 PCa 进展的关键分子机制对于开发转移性 PCa 的新疗法仍然至关重要。此前，我们发现肿瘤抑制性 miR-99b-5p 在侵袭性非洲裔美国人 (AA) PCa 和欧洲裔美国人 (EA) CRPC 中频繁下调，导致 mTOR、雄激素受体 (AR) 和 HIF-1α 信号传导上调。鉴于 mTOR 和 HIF-1α 信号传导是触发上皮间质转化 (EMT) 激活的关键上游途径，我们假设 miR-99b-5p 可能在调节 EMT 介导的 PCa 转移中发挥关键的功能作用。为了检验这一假设，进行了一系列细胞生物学、生化和体外功能测定（伤口愈合、跨孔迁移、细胞/ECM粘附和毛细管样管形成测定）来检查 miR-99b-5p 的作用模拟调节 EMT 介导的 PCa 转移过程。我们的结果表明，miR-99b-5p 同时靶向 MTOR 和 AR 信号传导，导致 E-钙粘蛋白上调、Snail/N-钙粘蛋白/波形蛋白下调，并抑制 EMT 介导的 PCa 转移。单独使用 MiR-99b-5p 以及与恩杂鲁胺或阿比特龙联合使用可显着抑制 EMT 介导的 AA PCa 和 EA CRPC 转移。

Prostate cancer (PCa) is the most frequently diagnosed cancer and second leading cause of cancer deaths among American men. Androgen deprivation therapy (ADT) has been systemically applied as a first-line therapy for PCa patients. Despite the initial responses, the majority of patients under ADT eventually experienced tumor progression to castration-resistant prostate cancer (CRPC), further leading to tumor metastasis to distant organs. Therefore, identifying the key molecular mechanisms underlying PCa progression remains crucial for the development of novel therapies for metastatic PCa. Previously, we identified that tumor-suppressive miR-99b-5p is frequently downregulated in aggressive African American (AA) PCa and European American (EA) CRPC, leading to upregulation of mTOR, androgen receptor (AR), and HIF-1α signaling. Given the fact that mTOR and HIF-1α signaling are critical upstream pathways that trigger the activation of epithelial-mesenchymal transition (EMT), we hypothesized that miR-99b-5p may play a critical functional role in regulating EMT-mediated PCa metastasis. To test this hypothesis, a series of cell biology, biochemical, and in vitro functional assays (wound healing, transwell migration, cell/ECM adhesion, and capillary-like tube formation assays) were performed to examine the effects of miR-99b-5p mimic on regulating EMT-mediated PCa metastasis processes. Our results have demonstrated that miR-99b-5p simultaneously targets MTOR and AR signaling, leading to upregulation of E-cadherin, downregulation of Snail/N-cadherin/Vimentin, and suppression of EMT-mediated PCa metastasis. MiR-99b-5p alone and in combination with enzalutamide or abiraterone significantly inhibits the EMT-mediated metastasis of AA PCa and EA CRPC.