Xinxiang Key Laboratory of Tumor Migration and Invasion Precision Medicine, School of Medical Technology, Xinxiang Medical University, Xinxiang, 453003, Henan Province, P.R. China.
Henan Key Laboratory of Immunology and Targeted Therapy, School of Medical Technology, Xinxiang Medical University, Xinxiang, 453003, Henan Province, P.R. China.
J Exp Clin Cancer Res. 2024 Aug 31;43(1):249. doi: 10.1186/s13046-024-03160-2.
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.
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.
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.
Our study revealed the possibility that inhibiting USP36 combined with tamoxifen could provide a potential therapy for breast cancer.
乳腺癌是全球女性最常见的癌症。过激活的雌激素受体（ER）α信号被认为是腔乳腺癌的主要因素，可通过选择性雌激素受体调节剂（SERM）如他莫昔芬有效治疗。然而，大约 30-40%的 ER+乳腺癌病例在他莫昔芬治疗后复发。这意味着乳腺癌的治疗仍然受到对他莫昔芬的耐药性的阻碍。最近的研究表明，ERα的翻译后修饰在内分泌抵抗中起重要作用。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，人类基因组中大约编码了 100 种去泛素酶，但尚不清楚哪些去泛素酶在雌激素信号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的关键去泛素酶，包括 ERα表达和稳定性的控制，对于改善乳腺癌治疗至关重要。
我们使用了几种 ER 阳性乳腺癌细胞系、DUB siRNA 文库筛选、异种移植模型、内分泌抵抗（ERα-Y537S）模型，并进行了免疫印迹、实时 PCR、RNA 测序、免疫荧光和荧光素酶活性测定，以研究 USP36 在乳腺癌进展和他莫昔芬耐药中的作用。
在这项研究中，我们通过 DUB siRNA 文库筛选鉴定出泛素特异性肽酶 36（USP36）作为一种关键的去泛素酶，参与 ERα 信号和乳腺癌的进展。体外和体内研究表明，USP36 而不是其无催化活性的突变体（C131A），可以通过 ERα 信号促进乳腺癌的进展。相反，沉默 USP36 抑制了肿瘤发生。在对内分泌治疗耐药的模型中，沉默 USP36 使耐药形式的 ERα（Y537S）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 连接多泛素化，并增强了 ERα 的转录组。有趣的是，我们的结果表明 USP36 是一种治疗乳腺癌的新型生物标志物。
我们的研究揭示了抑制 USP36 与他莫昔芬联合应用可能为乳腺癌提供一种潜在的治疗方法。
