Background: Tamoxifen is the cornerstone of adjuvant therapy for hormone receptor-positive breast cancer. Despite its efficacy, limited drug sensitivity and endocrine resistance remain the important clinical challenges. The main objective of this study was to investigate fatostatin, which was found to sensitize breast cancer to the antitumour effect of tamoxifen both in vitro and in vivo.
Methods: Fatostatin-induced ER degradation was detected by immunoprecipitation assay. The antitumour effect of fatostatin and tamoxifen on MCF-7 and T47D cells was assessed by MTT and colony forming assays. Cell cycle arrest was detected by flow cytometric analysis. Apoptosis was detected by annexin V/propidium iodide double staining and TUNEL assay. Autophagy was detected by MDC assay and acridine orange staining. Migration and invasion assays were performed using a Transwell system, and the efficacy of the synergistic use of fatostatin and tamoxifen in vivo was evaluated using an MCF-7 xenograft model in BALB/c nu/nu female mice.
Results: The synergistic use of fatostatin and tamoxifen significantly suppressed cell viability and invasion, induced cell cycle arrest, and regulated apoptosis and autophagy in MCF-7 and T47D cell lines via PI3K-AKT-mTOR signalling. Additionally, the expression levels of Atg7/12/13, beclin and LC3B increased while p-mTOR and P62 expression levels decreased after treatment with fatostatin and tamoxifen. Tumor growth in the xenograft model was suppressed significantly with the synergistic treatment of fatostatin and tamoxifen.
Conclusion: Fatostatin could induce ER degradation by K48-linked polyubiquitination, which was the key mechanism contributing to tamoxifen inhibition of PI3K-AKT-mTOR signalling in breast cancer. Fatostatin may have a promising clinical use for ER-positive breast cancer patients.



中文翻译：

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Fatostatin 与他莫昔芬联合使用可在 ER 阳性乳腺癌中产生协同抑制作用。

背景：他莫昔芬是激素受体阳性乳腺癌辅助治疗的基石。尽管其有效，但有限的药物敏感性和内分泌耐药性仍然是重要的临床挑战。本研究的主要目的是研究脂肪抑素，发现脂肪抑素可使乳腺癌在体外和体内对他莫昔芬的抗肿瘤作用敏感。
方法：通过免疫沉淀测定法检测Fatostatin诱导的ER降解。通过 MTT 和集落形成测定评估脂肪抑素和他莫昔芬对 MCF-7 和 T47D 细胞的抗肿瘤作用。通过流式细胞仪分析检测细胞周期停滞。通过膜联蛋白V/碘化丙啶双染色和TUNEL法检测细胞凋亡。通过MDC法和吖啶橙染色检测自噬。使用 Transwell 系统进行迁移和侵袭测定，并在 BALB/c nu/nu 雌性小鼠中使用 MCF-7 异种移植模型评估体内协同使用fatostatin 和他莫昔芬的功效。
结果：脂肪抑素和他莫昔芬的协同使用显着抑制细胞活力和侵袭，诱导细胞周期停滞，并通过 PI3K-AKT-mTOR 信号传导调节 MCF-7 和 T47D 细胞系的细胞凋亡和自噬。此外，在脂肪抑素和他莫昔芬治疗后，Atg7/12/13、beclin 和 LC3B 的表达水平增加，而 p-mTOR 和 P62 的表达水平降低。脂肪抑素和他莫昔芬的协同治疗显着抑制了异种移植模型中的肿瘤生长。
结论： Fatostatin 可通过 K48 连接的多泛素化诱导 ER 降解，这是他莫昔芬抑制乳腺癌 PI3K-AKT-mTOR 信号通路的关键机制。Fatostatin 可能对 ER 阳性乳腺癌患者具有良好的临床应用前景。