Department of Pathology and Cell Biology, College of Medicine, University of South Florida,Tampa, FL 33612, USA.
Gynecol Oncol. 2010 Feb;116(2):262-8. doi: 10.1016/j.ygyno.2009.10.052. Epub 2009 Nov 10.
Aggressive clinical course and difficult detection of ovarian cancer are major challenges to improving patient survival and necessitate avid investigation into more effective therapeutic approaches. Understanding early molecular and pathological changes in high risk patients, such as BRCA1 mutation carriers, can provide candidates for molecular profiling and novel targets for effective therapies.
Using a culture model system for normal human ovarian surface epithelial cells with and without the BRCA1 185delAG frameshift mutation for the truncated protein product, BRAt, we investigated the role of BRAt in enhanced chemosensitivity. We used MTS, Western immunoblot, semi-quantitative RT-PCR, luciferase reporter and siRNA assays, to identify novel downstream targets of BRAt that promote apoptosis following chemotherapeutic treatment.
We identified maspin as a novel downstream target of BRAt. BRAt increases maspin expression with preferential nuclear localization of maspin. Further, Brat-mediated maspin expression is transcriptionally regulated through an AP1 site within the (-520) to (-297) region of the promoter. Lastly, BRAt, enhances chemosensitivity in normal ovarian surface epithelial cells through c-Jun by a mechanism that may involve maspin.
BRAt-mediated enhanced chemosensitivity correlates clinically with enhanced chemotherapeutic response in BRCA1 mutation carriers. BRAt-mediated maspin expression also correlates with improved prognostic outlook for ovarian tumors with high levels of nuclear maspin. Consequently, understanding early genotypic and phenotypic changes in the context of high risk disease may provide a better understanding of the mechanism of mutation-associated ovarian cancer and provide new targets for therapeutic intervention.
卵巢癌具有侵袭性的临床病程和难以检测的特点，这是提高患者生存率的主要挑战，因此需要积极探索更有效的治疗方法。了解高风险患者（如 BRCA1 突变携带者）的早期分子和病理变化，可以为分子谱分析提供候选者，并为有效治疗提供新的靶点。
我们使用正常人类卵巢表面上皮细胞的培养模型系统，该系统携带有或不带有 BRCA1 185delAG 移码突变的截短蛋白产物 BRAt，研究了 BRAt 在增强化疗敏感性中的作用。我们使用 MTS、Western 免疫印迹、半定量 RT-PCR、荧光素酶报告和 siRNA 分析，鉴定了 BRAt 促进化疗后细胞凋亡的新下游靶标。
我们确定了 maspin 是 BRAt 的一个新的下游靶标。BRAt 增加了 maspin 的表达，并且 maspin 优先定位于核内。此外，Brat 介导的 maspin 表达是通过启动子的 (-520) 到 (-297) 区域内的 AP1 位点进行转录调控的。最后，BRAt 通过一种可能涉及 maspin 的机制，增强了正常卵巢表面上皮细胞的化疗敏感性。
BRAt 介导的增强化疗敏感性与 BRCA1 突变携带者的增强化疗反应具有临床相关性。BRAt 介导的 maspin 表达也与核内 maspin 水平较高的卵巢肿瘤的预后改善相关。因此，了解高危疾病背景下的早期基因型和表型变化，可以更好地理解与突变相关的卵巢癌的机制，并为治疗干预提供新的靶点。
