Novel protein kinase signaling associated with platinum resistance in ovarian cancer

项目摘要 铂类耐药的发展是导致卵巢癌的最重要因素之一 复发率和死亡率。在我们努力破译铂抵抗的分子机制时，我们 对铂耐药的SK-OV3卵巢癌细胞系进行了全激酶组筛选，并鉴定了Src- 相关激酶缺乏C-末端调节酪氨酸和N-末端肉豆蔻基化位点（SRMS）作为顶部 铂电阻调节器对TCGA卵巢癌数据集的进一步分析显示， SRMS表达对铂类药物治疗反应较差，总体生存率较差。自从击倒 的SRMS对p53缺陷型卵巢癌细胞系具有明显的铂致敏作用，但仅显示轻微的作用 在p53感受态细胞系上，我们推断SRMS在p53缺陷型细胞的铂抗性中起关键作用。 卵巢癌为了收集对SRMS在铂抗性中的作用的机理见解，我们表明， SRMS可能通过直接磷酸化JNK来阻止JNK活化。JNK信号通路是良好的 作为细胞毒性药物引发细胞凋亡的重要介质;我们观察到SRMS是 在p53缺陷细胞中特异性地参与铂抗性表明：1）铂诱导细胞凋亡， 由于p53缺陷，p53缺陷卵巢癌细胞以JNK信号通路依赖的方式 信号通路介导的细胞凋亡;和2）SRMS导致的JNK信号转导抑制增强了铂诱导的细胞凋亡。 凋亡，从而促进p53缺陷细胞中的铂抗性。p53在高水平中均匀缺乏， 分级浆液性卵巢癌（HGSOC）。发现SRMS在p53- 表明SRMS可能是治疗HGSOC铂耐药的理想靶点。在 我们的"药物再利用"筛选，我们发现PLX4720，一种B-RafV600E的选择性抑制剂，可以有效地 抑制SRMS活性。在本申请中，我们提出了3个具体目标：1）表征分子机制 潜在SRMS赋予的铂耐药; 2）定义铂耐药相关事件， 由SRMS-JNK信号传导控制;和3）研究靶向SRMS以增加 铂治疗这一应用的成功将揭示SRMS作用的分子机制， 卵巢癌的铂耐药性。重要的是，我们将评估针对SRMS的战略，以克服 卵巢癌的铂耐药

PROJECT SUMMARY Development of platinum resistance is one of the most important factors contributing to ovarian cancer recurrence and mortality. In our effort to decipher molecular mechanisms underlying platinum resistance, we performed a kinome-wide screening on platinum-resistant SK-OV3 ovarian cancer cell line and identified Src- Related Kinase Lacking C-Terminal Regulatory Tyrosine And N-Terminal Myristylation Sites (SRMS) as a top platinum resistance regulator. Further analysis of TCGA ovarian cancer dataset revealed that patients with high SRMS expression responded poorly to platinum-based therapy and had worse overall survival. Since knockdown of SRMS markedly sensitized p53-deficient ovarian cancer cell lines to platinum while only displayed minor effect on p53-competent cell lines, we reason that SRMS plays a critical role in platinum resistance of p53-deficient ovarian cancer. To glean the mechanistic insight into the role of SRMS in platinum resistance, we showed that SRMS prevents JNK activation, possibly by directly phosphorylating JNKs. JNK signaling pathway is well established as an essential mediator for apoptosis triggered by cytotoxic agents; our observation that SRMS is specifically involved in platinum resistance in p53-deficient cells suggests that 1) platinum induces apoptosis in p53-deficient ovarian cancer cells in a JNK signaling pathway-dependent manner because of the defect in p53 signaling pathway-mediated apoptosis; and 2) SRMS-led inhibition of JNK signaling alleviates platinum-induced apoptosis and thereby promotes platinum resistance in p53-deficient cells. p53 is uniformly deficient in high grade serous ovarian cancer (HGSOC). The discovery of SRMS’ prominent role in platinum resistance of p53- deficient cells indicates that SRMS can be an ideal therapeutic target against platinum resistance in HGSOC. In our “drug repurposing” screening, we found that PLX4720, a selective inhibitor of B-RafV600E, can potently inhibit SRMS activity. In this application, we propose 3 specific aims: 1) Characterize molecular mechanisms underlying SRMS-conferred platinum resistance; 2) Define platinum resistance-relevant events that are governed by SRMS-JNK signaling; and 3) Investigate the potential of targeting SRMS to augment efficacy of platinum therapy. The success of this application will uncover molecular mechanism underlying SRMS’ role in platinum resistance of ovarian cancer. Importantly, we will evaluate SRMS-targeted strategy to overcome platinum resistance in ovarian cancer.