Molecular Oncology Laboratory of Cancer Research Institute, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning, PR China.
The People's Hospital of Liaoning Province, No.33 Wenyi Road, Shenhe District, Shenyang, Liaoning, PR China.
Biomed Pharmacother. 2020 Apr;124:109852. doi: 10.1016/j.biopha.2020.109852. Epub 2020 Jan 20.
Breast cancer is the most common malignant tumor in women. Due to limited treatment outcome and high rate of metastasis, the prognosis is especially poor for triple-negative breast cancer. It is urgent to discover and develop novel agents for treatment of breast cancer. Herein, we investigated the potential mechanisms of Oleandrin's (a cardiac glycoside) cytotoxic activity against breast cancer cells.
Cell proliferation was assessed by xCELLigence Real-Time Cell Analyzer (RTCA)-MP system. Apoptotic cells were detected by using Annexin V/PI staining and nuclear fragments observation. The effect of oleandrin on ATP1B3 expression and markers of ER stress were determined by western blot. A primary cell sensitivity assay was performed via a collagen gel droplet-embedded culture drug sensitivity method (CD-DST).
Oleandrin suppressed cell proliferation and colony formation in the three breast cancer cell lines but did not affect normal mammary epithelial cells. Additionally, the expression of ATP1B3 was higher in the three breast cancer cell lines compared to MCF10A cells. Treatment with oleandrin increased the number of apoptotic cells and led to nuclear pyknosis, fragmentation, and apoptotic body formation in breast cancer cells. Furthermore, oleandrin treatment increased expression of Bax and Bim but decreased that of Bcl-2. Treatment with oleandrin also upregulated the expression of endoplasmic reticulum stress associated proteins, including eIF2α, ATF4, and CHOP, but not PERK. oleandrin treatment also induced the phosphorylation of PERK and eIF2α. Of note, oleandrin exhibited antitumor effects on patient-derived breast cancer cells under three-dimensional culture conditions.
Taken together, our results suggest that oleandrin induces mitochondrial-mediated apoptosis by activating endoplasmic reticulum stress in breast cancer. Moreover, oleandrin may be an effective strategy for the treatment of breast cancer.
乳腺癌是女性最常见的恶性肿瘤。由于治疗效果有限且转移率高，三阴性乳腺癌的预后尤其差。因此，迫切需要发现和开发治疗乳腺癌的新型药物。在此，我们研究了欧夹竹桃苷（一种强心苷）对乳腺癌细胞细胞毒性的潜在机制。
采用 xCELLigence 实时细胞分析（RTCA）-MP 系统评估细胞增殖。通过 Annexin V/PI 染色和核片段观察检测凋亡细胞。通过 Western blot 测定欧夹竹桃苷对 ATP1B3 表达和 ER 应激标志物的影响。通过胶原凝胶滴包埋培养药物敏感性法（CD-DST）进行原代细胞敏感性测定。
欧夹竹桃苷抑制三种乳腺癌细胞系的细胞增殖和集落形成，但对正常乳腺上皮细胞没有影响。此外，与 MCF10A 细胞相比，三种乳腺癌细胞系中 ATP1B3 的表达更高。欧夹竹桃苷处理增加了凋亡细胞的数量，并导致乳腺癌细胞出现核固缩、碎裂和凋亡小体形成。此外，欧夹竹桃苷处理增加了 Bax 和 Bim 的表达，但降低了 Bcl-2 的表达。欧夹竹桃苷处理还上调了内质网应激相关蛋白的表达，包括 eIF2α、ATF4 和 CHOP，但不包括 PERK。欧夹竹桃苷处理还诱导了 PERK 和 eIF2α 的磷酸化。值得注意的是，欧夹竹桃苷在三维培养条件下对患者来源的乳腺癌细胞表现出抗肿瘤作用。
综上所述，我们的研究结果表明，欧夹竹桃苷通过激活内质网应激诱导乳腺癌中线粒体介导的细胞凋亡。此外，欧夹竹桃苷可能是治疗乳腺癌的有效策略。
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