School of Agriculture, Yunnan University, Kunming, 650500, Yunnan, China.
College of Agriculture and Life Sciences, Kunming University, Kunming, 650241, Yunnan, China.
Breast Cancer. 2019 Nov;26(6):766-775. doi: 10.1007/s12282-019-00980-5. Epub 2019 Jun 6.
Icariin is a major component isolated from Epimedium brevicornum Maxim and has been reported to exhibit anti-tumor activity. However, whether icariin could reverse the acquired drug resistance in breast cancer remains largely unclear. Therefore, this study was designed to explore the antitumor effects of icariin and its underlying mechanisms in a tamoxifen-resistant breast cancer cell line MCF-7/TAM.
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Lactate dehydrogenase (LDH) assay were performed to determine the effects of icariin on cell viability and cell death. Cell cycle progression and apoptosis were detected by flow cytometry analysis. Transmission electron microscopy (TEM) assay was utilized to observe cell autophagy. The downstream protein levels were measured using western blotting.
Here, we observed that icariin treatment not only inhibited the growth of MCF-7 but also has a potential function to overcome tamoxifen resistance in MCF-7/TAM. Moreover, icariin significantly induced cell cycle G0/G1 phase arrest and apoptosis, as well as suppressed autophagy. At molecular levels, icariin treatment remarkably down-regulated the expression levels of CDK2, CDK4, Cyclin D1, Bcl-2, LC3-1, LC3-II, AGT5, Beclin-1, but upregulated the expression levels of caspase-3, PARP and p62. Most importantly, we found inhibition of autophagy via 3-MA treatment could significantly enhance the effects of icariin on cell viability and apoptosis. Enhanced autophagy via autophagy related 5 (ATG5) overexpression could partially reverse the effects of icariin on cell viability and apoptosis.
These results revealed that icariin might potentially be useful as an adjuvant agent in cancer chemotherapy to enhance the effect of tamoxifen through suppression of autophagy in vitro and provide insight into the therapeutic potential of icariin for the treatment of chemo-resistant breast cancer.
淫羊藿苷是从淫羊藿中分离得到的主要成分，已被报道具有抗肿瘤活性。然而，淫羊藿苷是否能逆转乳腺癌的获得性耐药性仍不清楚。因此，本研究旨在探讨淫羊藿苷在他莫昔芬耐药乳腺癌 MCF-7/TAM 细胞系中的抗肿瘤作用及其机制。
采用 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）法和乳酸脱氢酶（LDH）法检测淫羊藿苷对细胞活力和细胞死亡的影响。采用流式细胞术分析检测细胞周期进展和细胞凋亡。采用透射电子显微镜（TEM）观察细胞自噬。采用 Western blot 检测下游蛋白水平。
本研究观察到淫羊藿苷不仅能抑制 MCF-7 的生长，而且还具有克服 MCF-7/TAM 中他莫昔芬耐药的作用。此外，淫羊藿苷能显著诱导细胞周期 G0/G1 期阻滞和细胞凋亡，并抑制自噬。在分子水平上，淫羊藿苷处理显著下调 CDK2、CDK4、Cyclin D1、Bcl-2、LC3-1、LC3-II、AGT5、Beclin-1 的表达水平，而上调 caspase-3、PARP 和 p62 的表达水平。重要的是，我们发现通过 3-MA 抑制自噬可以显著增强淫羊藿苷对细胞活力和凋亡的影响。通过过表达自噬相关蛋白 5（ATG5）增强自噬可以部分逆转淫羊藿苷对细胞活力和凋亡的影响。
这些结果表明，淫羊藿苷可能作为癌症化疗的辅助药物具有潜在的应用价值，通过抑制自噬增强他莫昔芬的作用，为治疗化疗耐药性乳腺癌提供了新的治疗靶点。
