PO.MCB06.01 · 分子与细胞生物学
组蛋白赖氨酸去甲基化酶 4B 对他莫昔芬敏感和耐药乳腺癌细胞癌症治疗的表观遗传调控
Epigenetic regulation of histone lysine demethylase 4B on cancer therapy in tamoxifen-sensitive and -resistant breast cancer cells
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景：组蛋白赖氨酸去甲基化酶 4B（KDM4B）是一种关键的组蛋白赖氨酸去甲基化酶，在乳腺癌中异常过表达，并作为 ERalpha 信号传导的重要表观遗传共激活因子发挥功能。尽管其在乳腺肿瘤发生中的致癌作用已被确立，但 KDM4B 在他莫昔芬敏感与他莫昔芬耐药状态下的功能差异及其潜在分子机制仍知之甚少。阐明 KDM4B 对内分泌耐药演变的贡献，对于识别新的治疗靶点以及推进克服内分泌治疗耐药的精准策略至关重要。
方法：使用 TCGA 和 GTEx 数据集评估 KDM4B 在人类各种癌症和正常组织中的表达。为研究其功能作用，我们比较了 KDM4B 调控在 ERalpha 阳性 MCF-7 细胞及其他莫昔芬耐药衍生细胞 MCF-7 TamR 中的效应。通过 siRNA 介导的敲低或使用选择性 KDM4B 抑制剂 B3 进行药理学抑制来抑制 KDM4B。通过 MTT 和集落形成实验测定细胞增殖。通过 Western blot 检测 ERalpha、Bcl-2、H3K9me3、Cyclin D1、c-Myc 及相关信号分子的蛋白表达水平。使用流式细胞术分析细胞周期进展和凋亡。使用 Seahorse 糖酵解应激试验评估代谢重编程。
结果：TCGA 和 GTEx 分析显示，与正常乳腺组织相比，KDM4B 在乳腺癌中显著过表达。与之一致，相对于亲本 MCF-7 细胞，KDM4B 水平在他莫昔芬耐药的 MCF-7（TamR）细胞中明显升高。通过 siRNA 介导的敲低或药理学抑制来抑制 KDM4B，显著降低了 MCF-7 和 TamR 细胞的增殖能力和集落形成能力。KDM4B 缺失恢复了 H3K9me3 富集，降低了 ERalpha 表达，并诱导 G1/S 细胞周期阻滞。此外，代谢分析表明，KDM4B 抑制减弱了糖酵解活性，提示其在代谢重编程中的作用。
结论：KDM4B 在他莫昔芬敏感和他莫昔芬耐药的 ERalpha 阳性乳腺癌中均作为关键的表观遗传调控因子。抑制 KDM4B 可恢复抑制性组蛋白标记，抑制 ERalpha 依赖性转录，并减弱细胞增殖和代谢活性。他莫昔芬耐药细胞对 KDM4B 的高度依赖进一步凸显了其作为克服内分泌治疗耐药的有前景治疗靶点的潜力。
查看英文原文 English abstract
Background: Histone lysine demethylase 4B (KDM4B), a key histone lysine demethylase, is aberrantly overexpressed in breast cancer and functions as an essential epigenetic co-activator of ERalpha signaling. Although its oncogenic role in breast tumorigenesis has been established, the functional distinctions and underlying molecular mechanisms of KDM4B in tamoxifen-sensitive versus tamoxifen-resistant states remain poorly defined. Elucidating KDM4B's contribution to the evolution of endocrine resistance will be critical for identifying novel therapeutic targets and advancing precision strategies to overcome resistance to endocrine therapy.
Methods: KDM4B expression across human cancers and normal tissues was evaluated using TCGA and GTEx datasets. To investigate its functional role, we compared the effects of KDM4B modulation in ERalpha-positive MCF-7 cells and their tamoxifen-resistant derivative, MCF-7 TamR. KDM4B was suppressed either by siRNA-mediated knockdown or by pharmacological inhibition using the selective KDM4B inhibitor B3. Cell proliferation was measured through MTT and colony formation assays. Protein expression levels of ERalpha, Bcl-2, H3K9me3, Cyclin D1, c-Myc, and related signaling molecules were examined via Western blotting. Cell-cycle progression and apoptosis were analyzed using flow cytometry. Metabolic reprogramming was evaluated using the Seahorse glycolytic stress test.
Results: TCGA and GTEx analyses revealed that KDM4B is significantly overexpressed in breast cancer compared with normal breast tissue. Consistently, KDM4B levels were markedly elevated in tamoxifen-resistant MCF-7 (TamR) cells relative to parental MCF-7 cells. Suppression of KDM4B through siRNA-mediated knockdown or pharmacological inhibition substantially reduced the proliferative capacity and colony-forming ability of both MCF-7 and TamR cells. KDM4B depletion restored H3K9me3 enrichment, decreased ERalpha expression, and induced G1/S cell-cycle arrest. In addition, metabolic profiling demonstrated that KDM4B inhibition attenuated glycolytic activity, indicating a role in metabolic reprogramming.
Conclusion: KDM4B serves as a critical epigenetic regulator in both tamoxifen-sensitive and tamoxifen-resistant ERalpha-positive breast cancer. Inhibition of KDM4B restores repressive histone marks, suppresses ERalpha-dependent transcription, and attenuates cellular proliferation and metabolic activity. The heightened dependence of tamoxifen-resistant cells on KDM4B further underscores its potential as a promising therapeutic target for overcoming endocrine therapy resistance.
利益披露 Disclosure
T. Zheng, None..
J. Kim, None..
H. Noh, None..
H. Kim, None.