背景:乳腺癌是全球女性中最普遍的癌症。过度激活的雌激素受体(ER)α信号被认为是管腔内乳腺癌的主要因素,可以用选择性雌激素受体调节剂(SERM)如他莫昔芬有效管理。然而,大约30-40%的ER+乳腺癌病例在他莫昔芬治疗后复发.这意味着对他莫昔芬的抗性仍然阻碍了乳腺癌的治疗。最近的研究表明,ERα的翻译后修饰在内分泌抵抗中起着重要作用。ERα蛋白及其转录组的稳定性受E3泛素连接酶和去泛素酶之间的平衡调节。根据目前的知识,大约100个去泛素酶被编码在人类基因组中,但目前尚不清楚哪些去泛素酶在雌激素信号传导和内分泌抵抗中起关键作用.因此,解码显著影响雌激素信号传导的关键去泛素酶,包括ERα表达和稳定性的控制,对乳腺癌治疗的改善至关重要。
方法:我们使用了几种ER阳性乳腺癌细胞系,DUBsiRNA文库筛选,异种移植模型,内分泌抵抗(ERα-Y537S)模型并进行免疫印迹,实时PCR,RNA测序,免疫荧光,和荧光素酶活性测定研究USP36在乳腺癌进展和他莫昔芬耐药中的作用。
结果:在这项研究中,我们确定泛素特异性肽酶36(USP36)是参与ERα信号传导和乳腺癌进展的关键去泛素化酶,通过去泛素化酶siRNA文库筛选.体外和体内研究表明,USP36,而不是其催化失活突变体(C131A),可以通过ERα信号促进乳腺癌进展。相反,沉默USP36抑制肿瘤发生。在抗内分泌治疗的模型中,沉默USP36使ERα(Y537S)的抗性形式不稳定,并恢复了对他莫昔芬的敏感性。分子研究表明,USP36抑制了ERα的K48连接的多泛素化并增强了ERα转录组。有趣的是,我们的结果表明USP36是治疗乳腺癌的新型生物标志物。
结论:我们的研究揭示了抑制USP36联合他莫昔芬治疗乳腺癌的可能性。
BACKGROUND: Breast cancer is the most prevalent cancer in women globally. Over-activated estrogen receptor (ER) α signaling is considered the main factor in luminal breast cancers, which can be effectively managed with selective estrogen receptor modulators (SERMs) like tamoxifen. However, approximately 30-40% of ER + breast cancer cases are recurrent after tamoxifen therapy. This implies that the treatment of breast cancer is still hindered by resistance to tamoxifen. Recent studies have suggested that post-translational modifications of ERα play a significant role in endocrine resistance. The stability of both ERα protein and its transcriptome is regulated by a balance between E3 ubiquitin ligases and deubiquitinases. According to the current knowledge, approximately 100 deubiquitinases are encoded in the human genome, but it remains unclear which deubiquitinases play a critical role in estrogen signaling and endocrine resistance. Thus, decoding the key deubiquitinases that significantly impact estrogen signaling, including the control of ERα expression and stability, is critical for the improvement of breast cancer therapeutics.
METHODS: We used several ER positive breast cancer cell lines, DUB siRNA library screening, xenograft models, endocrine-resistant (ERα-Y537S) model and performed immunoblotting, real time PCR, RNA sequencing, immunofluorescence, and luciferase activity assay to investigate the function of USP36 in breast cancer progression and tamoxifen resistance.
RESULTS: In this study, we identify Ubiquitin-specific peptidase 36 (USP36) as a key deubiquitinase involved in ERα signaling and the advancement of breast cancer by deubiquitinases siRNA library screening. In vitro and in vivo studies showed that USP36, but not its catalytically inactive mutant (C131A), could promote breast cancer progression through ERα signaling. Conversely, silencing USP36 inhibited tumorigenesis. In models resistant to endocrine therapy, silencing USP36 destabilized the resistant form of ERα (Y537S) and restored sensitivity to tamoxifen. Molecular studies indicated that USP36 inhibited K48-linked polyubiquitination of ERα and enhanced the ERα transcriptome. It is interesting to note that our results suggest USP36 as a novel biomarker for treatment of breast cancer.
CONCLUSIONS: Our study revealed the possibility that inhibiting USP36 combined with tamoxifen could provide a potential therapy for breast cancer.