斯钙素1通过BRCA1调节三阴性乳腺癌顺铂敏感性的作用及机制研究

Stanniocalcin 1 (STC1) can regulate breast cancer cell proliferation, invasion and metastasis. However, the influence of STC1 on DNA damage repair and chemosensitivity is still unclear. Our previous studies showed that STC1 expression in triple negative breast cancer (TNBC) cells is more robust, and STC1 can regulate BRCA1 phosphorylation and influence Cisplatin sensitivity of breast cancer cells. But the mechanism needs further investigation. Therefore, we put forward the hypothesis that STC1 can enhance DNA damage repair ability of breast cancer cells via promoting BRCA1 expression or phosphorylation, resulting in Cisplatin resistance of breast cancer cells, and that STC1 can be a predictive factor of Cisplatin sensitivity in TNBC. To test our hypothesis, we will explore the regulation between STC1 and BRCA1, and the role of STC1 in Cisplatin sensitivity of breast cancer from molecular, cellular, animal level and human tissue by establishing Cisplatin-resistant breast cancer cell model and by constructing breast cancer cell lines with different STC1 expression, using qPCR, Western Blot, Lentivirus transfection, RNA interference and other experimental means. Our project will confirm the role and mechanism of STC1 during the occurrence of Cisplatin resistance in breast cancer, and finally, to provide new insights for individualized treatment of triple negative breast cancer.

斯钙素1（Stanniocalcin 1，STC1）对乳腺癌细胞增殖、侵袭转移等过程均有调节作用，但与DNA损伤修复及化疗敏感性的关系尚不明确。我们的预实验结果提示三阴性乳腺癌细胞中STC1表达水平较高，且STC1能调节BRCA1磷酸化并影响乳腺癌细胞顺铂敏感性，但机制有待探讨。据此我们提出假设：STC1通过促进BRCA1的表达或磷酸化而增强乳腺癌细胞DNA损伤修复能力，降低乳腺癌细胞对顺铂的敏感性，STC1表达水平可作为三阴性乳腺癌顺铂敏感性预测指标。为验证这一假设，我们将建立乳腺癌顺铂耐药细胞模型及构建不同STC1表达状态的乳腺癌细胞系，采用q-PCR、Western Blot、慢病毒转染、RNA干扰等手段，从分子、细胞、动物及人体组织水平探讨STC1与BRCA1的调节关系及其与顺铂敏感性的关系，明确STC1对顺铂敏感性的调节作用及机制，为三阴性乳腺癌个体化治疗提供新的思路和依据。

斯钙素1（Stanniocalcin 1，STC1）是一种糖蛋白激素，其异常表达与多种肿瘤相关，但其在乳腺癌中的功能还不是很明确。本研究通过对不同乳腺癌细胞株中STC1的表达干预，发现STC1能促进乳腺癌细胞增殖、生长，促进细胞克隆形成及侵袭转移，同时STC1能降低放射损伤所致的凋亡。同时我们发现STC1能促进X射线所致细胞DNA损伤修复，表现为BRCA1、53BP1、TopBP1等焦点形成增加。机制研究显示，STC1能与BRCA1相互结合，且在DNA损伤诱导后结合增加。通过对乳腺癌标本组织芯片免疫组化检测显示，STC1高表达与乳腺癌无病生存负相关，说明STC1表达可作为乳腺癌预后较差的评估指标。此外，我们还研究了斯钙素家族中另一个成员STC2与DNA损伤修复的关系，我们发现，与STC1相比，STC2亦能促进肿瘤细胞增殖，但其功能在HU所致复制压力调节上较为重要，表现在STC2敲低后，包括卵巢癌、结直肠癌细胞对HU敏感性显著增加，TopBP1、RPA32焦点形成明显受阻。其机制与STC2调节ERK的表达相关。综上，我们认为斯钙素对于调节DNA损伤修复有重要作用，且不同成员对不同形式的DNA损伤调节各有侧重，深入机制有待进一步研究。