Breast cancer is one of the most common cancers among females and is associated with high mortality and morbidity rates. Several studies have demonstrated that combination treatments with natural products and tamoxifen can improve the sensitivity and cytotoxicity of oestrogen-positive breast cancer cells in response to tamoxifen. Celastrol, a triterpene from traditional Chinese medicine, has been proven to exert significant anticancer effects on various cancers. Our study is aimed at exploring the interactive antitumour effects of celastrol combined with tamoxifen and the potential underlying anticancer mechanisms in MCF-7 cells. The results from MTT assays, isobolographic analyses, and clonogenic cell survival assays revealed that a combination of celastrol and tamoxifen exerted synergistic cytotoxic effects in MCF-7 cells. The results from Annexin V/PI staining and flow cytometry analysis suggested that celastrol enhanced tamoxifen-mediated apoptosis. In addition, exposure to a combination of celastrol and tamoxifen inhibited cell proliferation by causing G1 phase cell cycle arrest. Moreover, the distribution of LC3 was monitored by immunofluorescence, and the changes in the LC3II and P62 levels detected by western blot analysis suggested that celastrol in combination with tamoxifen triggered autophagy. Furthermore, the decrease in p-Akt and p-mTOR in MCF-7 cells, along with the increase in the autophagy marker proteins LC3II and P62, suggested that the Akt/mTOR pathway might be involved in the triggering of cell autophagy by the combination treatment. However, in an MCF-7-implanted nude mouse model, it was possible to detect significantly decreased tumour volumes and tumour weights and decreased p-Akt and p-mTOR protein expression in the celastrol+tamoxifen group. Therefore, our study provides the first evidence that celastrol combined with tamoxifen exerts synergistic anticancer effects by inducing apoptosis and autophagy in MCF-7 cells. Considering the urgent need for novel therapeutic strategies in anticancer therapy, this combinatorial approach is worthy of further investigation.

中文翻译：

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Celastrol联合他莫昔芬对MCF-7细胞凋亡和自噬的协同作用

乳腺癌是女性中最常见的癌症之一，并且与高死亡率和发病率有关。多项研究表明，天然产物和他莫昔芬联合治疗可以提高雌激素阳性乳腺癌细胞对他莫昔芬的敏感性和细胞毒性。Celastrol 是一种来自中药的三萜，已被证明对各种癌症具有显着的抗癌作用。我们的研究旨在探索 Celastrol 联合他莫昔芬的相互作用抗肿瘤作用以及 MCF-7 细胞中潜在的潜在抗癌机制。MTT 测定、等值线分析和克隆形成细胞存活测定的结果表明，celastrol 和他莫昔芬的组合在 MCF-7 细胞中发挥协同细胞毒作用。Annexin V/PI 染色和流式细胞术分析的结果表明，celastrol 增强了他莫昔芬介导的细胞凋亡。此外，暴露于 Celastrol 和他莫昔芬的组合通过导致 G1 期细胞周期停滞来抑制细胞增殖。此外，通过免疫荧光监测 LC3 的分布，通过蛋白质印迹分析检测到的 LC3II 和 P62 水平的变化表明，celastrol 与他莫昔芬联合引发了自噬。此外，MCF-7 细胞中 p-Akt 和 p-mTOR 的减少，以及自噬标记蛋白 LC3II 和 P62 的增加，表明 Akt/mTOR 通路可能参与了联合引发细胞自噬的过程。治疗。然而，在植入 MCF-7 的裸鼠模型中，在 celastrol + 他莫昔芬组中可以检测到显着降低的肿瘤体积和肿瘤重量以及降低的 p-Akt 和 p-mTOR 蛋白表达。因此，我们的研究提供了第一个证据，证明 Celastrol 联合他莫昔芬通过诱导 MCF-7 细胞凋亡和自噬发挥协同抗癌作用。考虑到抗癌治疗中迫切需要新的治疗策略，这种组合方法值得进一步研究。