Zhang Yuyang, Su Mingqin, Chen Yiming, Cui Li, Xia Wei, Xu Renfang, Xue Dong, Zhang Xiansheng, Feng Xingliang
Department of Urology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.
Institute of Urology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.
Clin Transl Med. 2025 Jan;15(1):e70164. doi: 10.1002/ctm2.70164.
Chromosomal instability (CIN), a hallmark of cancer, is commonly linked to poor prognosis in high-grade prostate cancer (PCa). Paradoxically, excessively high levels of CIN may impair cancer cell viability. Consequently, understanding how tumours adapt to CIN is critical for identifying novel therapeutic targets.
Bioinformatic analyses were conducted to identify genes overexpressed in PCa tissues using The Cancer Genome Atlas (TCGA) and GEO datasets. Western blotting and immunohistochemistry assays were applied to determine the expression levels of euchromatic histone lysine methyltransferase 2 (EHMT2), pT232-Aurora B and Cullin 3 (CUL3). The proliferation of cells was measured through CCK-8 tests, clonogenesis and subcutaneous xenografts of human PCa cells in BALB/c nude mice. Live cell imaging, immunofluorescence (IF) and flow cytometry were used to confirm the role of EHMT2 in PCa cell mitosis. Co-immunoprecipitation, Western blotting and IF assays further elucidated the underlying molecular mechanisms.
EHMT2 was highly expressed in metastatic PCa tissues exhibiting elevated CIN and was strongly associated with adverse clinical outcomes in patients with PCa. Silencing EHMT2 impaired cell division, inducing G2/M-phase arrest and mitotic catastrophe in PCa cells. Mechanistically, EHMT2 is indispensable to ensure the full activation of Aurora B through centromeric R-loop-driven ATR-CHK1 pathway, with EHMT2 protein expression peaking during the G2/M-phase. Moreover, CUL3 was identified as a binding partner of EHMT2, mediating its polyubiquitination and destabilising its protein levels.
This study reveals a CUL3-EHMT2-Aurora B regulatory axis that safeguards accurate chromosome segregation in PCa cells, supporting the potential therapeutic application of EHMT2 inhibitors.
Euchromatic histone lysine methyltransferase 2 (EHMT2) is overexpressed in advanced prostate cancer, restraining catastrophic chromosomal instability (CIN) and enhancing cell fitness. EHMT2 functions via the centromeric R-loop-driven ATR-CHK1-Aurora B pathway to promote chromosomal stability. EHMT2 confers enzalutamide resistance via activating Aurora B. Cullin 3 (CUL3) promotes EHMT2 destabilisation via deubiquitination.
染色体不稳定（CIN）是癌症的一个标志，通常与高级别前列腺癌（PCa）的不良预后相关。矛盾的是，过高水平的CIN可能会损害癌细胞的活力。因此，了解肿瘤如何适应CIN对于确定新的治疗靶点至关重要。
利用癌症基因组图谱（TCGA）和GEO数据集进行生物信息学分析，以鉴定在PCa组织中过表达的基因。应用蛋白质免疫印迹法和免疫组织化学分析来确定常染色质组蛋白赖氨酸甲基转移酶2（EHMT2）、pT232-极光激酶B和Cullin 3（CUL3）的表达水平。通过CCK-8试验、克隆形成实验以及人PCa细胞在BALB/c裸鼠中的皮下异种移植实验来检测细胞增殖情况。利用活细胞成像、免疫荧光（IF）和流式细胞术来证实EHMT2在PCa细胞有丝分裂中的作用。免疫共沉淀、蛋白质免疫印迹法和IF分析进一步阐明了潜在的分子机制。
EHMT2在表现出CIN升高的转移性PCa组织中高表达，并且与PCa患者的不良临床结局密切相关。沉默EHMT2会损害细胞分裂，导致PCa细胞出现G2/M期阻滞和有丝分裂灾难。从机制上讲，EHMT2对于通过着丝粒R环驱动的ATR-CHK1途径确保极光激酶B的完全激活是必不可少的，其蛋白表达在G2/M期达到峰值。此外，CUL3被鉴定为EHMT2的结合伴侣，介导其多聚泛素化并使其蛋白水平不稳定。
本研究揭示了一个CUL3-EHMT2-极光激酶B调节轴，该轴可保障PCa细胞中染色体的准确分离，支持了EHMT2抑制剂的潜在治疗应用。
常染色质组蛋白赖氨酸甲基转移酶2（EHMT2）在晚期前列腺癌中过表达，抑制灾难性染色体不稳定（CIN）并增强细胞适应性。EHMT2通过着丝粒R环驱动的ATR-CHK1-极光激酶B途径发挥作用，以促进染色体稳定性。EHMT2通过激活极光激酶B赋予恩杂鲁胺抗性。Cullin 3（CUL3）通过去泛素化促进EHMT2的不稳定。
