Bajbouj Khuloud, Shafarin Jasmin, Abdalla Maher Y, Ahmad Iman M, Hamad Mawieh
1 Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates.
2 Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
Tumour Biol. 2017 Oct;39(10):1010428317726184. doi: 10.1177/1010428317726184.
It is well established that several forms of cancer associate with significant iron overload. Recent studies have suggested that estrogen (E2) disrupts intracellular iron homeostasis by reducing hepcidin synthesis and maintaining ferroportin integrity. Here, the ability of E2 to alter intracellular iron status and cell growth potential was investigated in MCF-7 cells treated with increasing concentrations of E2. Treated cells were assessed for intracellular iron status, the expression of key proteins involved in iron metabolism, oxidative stress, cell survival, growth, and apoptosis. E2 treatment resulted in a significant reduction in hepcidin expression and a significant increase in hypoxia-inducible factor 1 alpha, ferroportin, transferrin receptor, and ferritin expression; a transient decrease in labile iron pool; and a significant increase in total intracellular iron content mainly at 20 nM/48 h E2 dose. Treated cells also showed increased total glutathione and oxidized glutathione levels, increased superoxide dismutase activity, and increased hemoxygenase 1 expression. Treatment with E2 at 20 nM for 48 h resulted in a significant reduction in cell growth (0.35/1 migration rate) and decreased cell survival (<80%) as compared with controls. Survivin expression significantly increased at 24 h post treatment with 5, 10, or 20 nM; however, that of γ-H2AX increased only after survivin levels dropped and only at the 20 nM E2 dose. Minimal upregulation and splitting of caspase 9 was only evident in cells treated with 20 nM E2; no changes in caspase 3 expression were evident. Although Annexin V staining studies showed that E2 treatment did not induce apoptosis, scanning electron microscopy studies showed marked membrane blebbing at 20 nM/48 h of E2. These findings suggest that estrogen treatment disrupts intracellular iron metabolism and precipitates adverse effects concerning cell viability, membrane integrity, and growth potential.
多种癌症与严重的铁过载相关，这一点已得到充分证实。最近的研究表明，雌激素（E2）通过减少铁调素合成和维持铁转运蛋白的完整性来破坏细胞内铁稳态。在此，研究了在经不同浓度E2处理的MCF-7细胞中，E2改变细胞内铁状态和细胞生长潜能的能力。对处理后的细胞进行细胞内铁状态、铁代谢相关关键蛋白的表达、氧化应激、细胞存活、生长及凋亡情况的评估。E2处理导致铁调素表达显著降低，缺氧诱导因子1α、铁转运蛋白、转铁蛋白受体和铁蛋白表达显著增加；不稳定铁池短暂减少；主要在20 nM/48 h E2剂量时细胞内总铁含量显著增加。处理后的细胞还表现出总谷胱甘肽和氧化型谷胱甘肽水平升高、超氧化物歧化酶活性增强以及血红素加氧酶1表达增加。与对照组相比，20 nM E2处理48 h导致细胞生长显著降低（迁移率为0.35/1）且细胞存活率下降（<80%）。用5、10或20 nM E2处理24 h后，存活素表达显著增加；然而，γ-H2AX的表达仅在存活素水平下降后且仅在20 nM E2剂量时增加。仅在20 nM E2处理的细胞中观察到半胱天冬酶9有轻微上调和裂解；半胱天冬酶3表达无明显变化。虽然膜联蛋白V染色研究表明E2处理未诱导细胞凋亡，但扫描电子显微镜研究显示在20 nM/48 h E2处理时出现明显的细胞膜泡状化。这些发现表明，雌激素处理会破坏细胞内铁代谢，并引发与细胞活力、膜完整性和生长潜能相关的不良反应。
