Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing-Hua University, Hsinchu 30013, Taiwan.
Department of Pathology and Laboratory Medicine, Taichung Veterans General Hospital, Taichung 40705, Taiwan.
Theranostics. 2021 Jun 26;11(16):7779-7796. doi: 10.7150/thno.58729. eCollection 2021.
The progression of prostate cancer (PCa) to castration-resistant PCa (CRPC) despite continuous androgen deprivation therapy is a major clinical challenge. Over 90% of patients with CRPC exhibit sustained androgen receptor (AR) signaling. KDM4B that removes the repressive mark H3K9me3/2 is a transcriptional activator of AR and has been implicated in the development of CRPC. However, the mechanisms of KDM4B involvement in CRPC remain largely unknown. Here, we sought to demonstrate the molecular pathway mediated by KDM4B in CRPC and to provide proof-of-concept evidence that KDM4B is a potential CRPC target. CRPC cells (C4-2B or CWR22Rv1) depleted with KDM4B followed by cell proliferation ( and xenograft), microarray, qRT-PCR, Seahorse Flux, and metabolomic analyses were employed to identify the expression and metabolic profiles mediated by KDM4B. Immunoprecipitation was used to determine the KDM4B-c-Myc interaction region. Reporter activity assay and ChIP analysis were used to characterize the KDM4B-c-Myc complex-mediated mechanistic actions. The clinical relevance between KDM4B and c-Myc was determined using UCSC Xena analysis and immunohistochemistry. We showed that KDM4B knockdown impaired CRPC proliferation, switched Warburg to OXPHOS metabolism, and suppressed gene expressions including those targeted by c-Myc. We further demonstrated that KDM4B physically interacted with c-Myc and they were co-recruited to the c-Myc-binding sequence on the promoters of metabolic genes (, , and ). Importantly, KDM4B and c-Myc synergistically promoted the transactivation of the promoter in a demethylase-dependent manner. We also provided evidence that KDM4B and c-Myc are co-expressed in PCa tissue and that high expression of both is associated with worse clinical outcome. KDM4B partners with c-Myc and serves as a coactivator of c-Myc to directly enhance c-Myc-mediated metabolism, hence promoting CRPC progression. Targeting KDM4B is thus an alternative therapeutic strategy for advanced prostate cancers driven by c-Myc and AR.
尽管持续进行雄激素剥夺治疗，前列腺癌（PCa）仍会进展为去势抵抗性前列腺癌（CRPC），这是一个主要的临床挑战。超过 90%的 CRPC 患者表现出持续的雄激素受体（AR）信号。去除抑制性标记 H3K9me3/2 的 KDM4B 是 AR 的转录激活因子，并且与 CRPC 的发展有关。然而，KDM4B 参与 CRPC 的机制在很大程度上仍然未知。在这里，我们试图证明 KDM4B 在 CRPC 中介导的分子途径，并提供 KDM4B 是潜在的 CRPC 靶点的概念验证证据。使用 KDM4B 耗竭的 CRPC 细胞（C4-2B 或 CWR22Rv1）进行细胞增殖（和异种移植）、微阵列、qRT-PCR、 Seahorse Flux 和代谢组学分析，以鉴定由 KDM4B 介导的表达和代谢谱。免疫沉淀用于确定 KDM4B-c-Myc 相互作用区域。报告基因活性测定和 ChIP 分析用于表征 KDM4B-c-Myc 复合物介导的机制作用。使用 UCSC Xena 分析和免疫组织化学确定 KDM4B 和 c-Myc 之间的临床相关性。我们表明，KDM4B 敲低会损害 CRPC 的增殖，将 Warburg 切换为 OXPHOS 代谢，并抑制基因表达，包括 c-Myc 靶向的基因。我们进一步证明 KDM4B 与 c-Myc 物理相互作用，并且它们被共同募集到代谢基因（、、和）的 c-Myc 结合序列上。重要的是，KDM4B 和 c-Myc 以依赖去甲基化酶的方式协同促进 启动子的转录激活。我们还提供了证据表明 KDM4B 和 c-Myc 在 PCa 组织中共同表达，并且两者的高表达与更差的临床结局相关。KDM4B 与 c-Myc 合作，作为 c-Myc 的共激活因子，直接增强 c-Myc 介导的代谢，从而促进 CRPC 的进展。因此，针对 KDM4B 是由 c-Myc 和 AR 驱动的晚期前列腺癌的另一种治疗策略。
