Supplementation with the antioxidant selenium is frequently performed in breast cancer patients to protect the normal tissue from radiation-induced side effects. However, concerns exist whether selenium also protects tumor cells from radiation-induced cell kill and thereby reduces the efficacy of radiotherapy. In this work, the effect of selenium administration on the radiosensitivity of breast cancer cells was evaluated in vitro. Physiological relevant selenium concentrations (70 and 140 µg/l) did not affect DNA double-strand breaks (γH2AX foci) after 4-Gy X-ray irradiation. Also apoptosis (caspase 3/7) after irradiation with 10 Gy was not influenced by selenium treatment in MDA-MB-231 and MCF7 cells. Most importantly, selenium supplementation did not impair the clonogenic survival of the breast cancer cell lines after irradiation (0, 2, 4, 6, 8 Gy). The data suggest that physiological relevant selenium concentrations administered in combination with radiation therapy do not deteriorate the efficacy of radiotherapy in breast cancer patients. However, randomized clinical trials comparing the effectiveness of radiotherapy and the associated side effects in patients with and without selenium supplementation are recommended.

中文翻译：

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硒不影响乳腺癌细胞系的放射敏感性。

在乳腺癌患者中经常进行抗氧化剂硒的补充，以保护正常组织免受辐射引起的副作用。然而，人们担心硒是否还能保护肿瘤细胞免受辐射诱导的细胞杀伤，从而降低放射治疗的功效。在这项工作中，在体外评估了硒对乳腺癌细胞放射敏感性的影响。生理相关的硒浓度（70和140 µg / l）对4-Gy X射线照射后的DNA双链断裂（γH2AX焦点）没有影响。在MDA-MB-231和MCF7细胞中，硒处理也不会影响10 Gy照射后的凋亡（胱天蛋白酶3/7）。最重要的是，补充硒不会损害放射线后乳腺癌细胞系的克隆形成存活（0、2、4、6，8 Gy）。数据表明，与放射疗法联合使用的生理相关硒浓度不会降低乳腺癌患者放射疗法的疗效。但是，建议进行随机临床试验，比较在有和没有硒补充的患者中放疗的有效性和相关的副作用。