MicroRNA-30e通过铁死亡途径调控乳腺癌放射敏感性的作用及其分子机制研究

Breast cancer is the most common malignancy in the world. The morbidity and mortality of breast cancer in China are higher than the word average. Radiotherapy is one of the frequently-used methods for breast cancer. However, the radioresistance of breast cancer limits the use of radiotherapy. Ferroptosis is dependent upon intracellular iron, but not other metals, and is morphologically, biochemically, and genetically distinct from apoptosis, necrosis, and autophagy. Activation of ferroptosis results in the non-apoptotic destruction of certain cancer cells. Solute carrier family seven member eleven (SLC7A11) is a subunit of the amino acid transport system that mediates the entry of cystine into cells in exchange for glutamate. Previously study shows that SLC7A11 participate in the ferroptosis. It has been reported that microRNAs can regulate the radiosensitivity of tumor by regulating the expression of certain genes and signaling pathways. Bioinformatics analysis shows that miR-30e potentially target the 3’UTR of SLC7A11 mRNA. In the preliminary studies, we find that miR-30e is able to reduce the mRNA and protein level of SLC7A11, suggesting that miR-30e may participate in the ferroptosis through regulating SLC7A11. Our results show that overexpression of miR-30e can increase the radiosensitivity of breast cancer cells. Furthermore, we observe that the MDA levels are increased by overexpression of miR-30e in breast cancer cells. Accordingly, we speculate that miR-30e may regulate the radiosensitivity of breast cancer through ferroptosis mediated pathway. In this study, we propose to investigate the critical effect of miR-30e on radiosensitivity of breast cancer and its molecular mechanism in vitro and in vivo. Our results may reveal a new approach for microRNAs on radiosensitivity and enrich the role of micoRNAs in the development of breast cancer. In addition, this study undoubtedly provide a new method for improving radiosensitivity and clinical radiotherapy of breast cancer.

放射治疗是乳腺癌常规的治疗手段，而乳腺癌患者产生放射抵抗限制了放射治疗的广泛应用。MicroRNAs通过调控基因的表达以及信号通路参与调节肿瘤的放射敏感性。我们前期研究发现miR-30e可靶向调节在铁死亡中发挥重要作用的SLC7A11。提高miR-30e表达后，乳腺癌细胞对辐照敏感性增加，并导致丙二醛（MDA）水平增加。因此，我们推测miR-30e可能通过铁死亡途径调控乳腺癌的放射敏感性。本项目将在大量预实验研究的基础上，拟采用体外细胞和体内动物模型深入进行miR-30e在乳腺癌放射敏感性中的关键作用及其分子机制的研究。研究结果无疑为提高乳腺癌放射敏感性及临床放射治疗效果提供新的理论和实验依据。因此，本研究无论对提高临床乳腺癌放射治疗疗效和预后评估的基础研究以及临床应用研究都具有重要的价值和意义。

放射治疗是乳腺癌常规的治疗手段，而乳腺癌患者产生放射抵抗限制了放射治疗的广泛应用。铁死亡（Ferroptosis）是一种新发现的细胞死亡模式。铁死亡主要由铁依赖的ROS富集及膜脂质过氧化损伤引起，涉及一系列复杂的生化反应、基因表达、调控和信号传导系统。MicroRNAs(miRNAs)是一类长度约19-25个核苷酸的非编码单链小分子RNA，具有高度保守性、时序性和组织特异性。MicroRNAs通过调控基因的表达以及信号通路参与调节肿瘤的放射敏感性。本项目采用体外细胞和体内动物模型对miR-30e在细胞铁死亡过程中的作用和对乳腺癌放射敏感性的作用及分子机制进行了深入研究。结果显示，qRT-PCR检测表明结果表明miR-30e在乳腺癌细胞系中的表达水平比正常乳腺细胞系显著降低。CCK-8和克隆形成检测表明miR-30e能够显著抑制乳腺癌细胞系的细胞活力和克隆形成能力。通过生物信息学方法和双荧光报告基因实验表明miR-30e在乳腺癌细胞中能够靶向SLC7A11。过表达miR-30e能够显著提高乳腺癌细胞释放铁死亡标志物MDA和铁离子的水平；而铁死亡抑制剂ferrostatin-1能够显著抑制这一过程，表明miR-30e诱导了乳腺癌细胞的铁死亡过程。CCK-8和克隆形成能力实验检测结果显示miR-30e显著促进乳腺癌细胞的电离辐射敏感性。透射电镜扫描结果进一步表明miR-30e通过铁死亡途径促进乳腺癌放射敏感性。体内乳腺癌动物模型实验结果表明miR-30e能够通过靶向SLC7A11调控铁死亡途径增强乳腺癌的放射治疗效果。本项研究结果为乳腺癌放射治疗敏感性的研究提供了新方向和新思路。此外，对提高临床乳腺癌放射治疗疗效和预后评估的基础研究以及临床应用研究都具有重要的价值和意义。