Novel protein kinase signaling associated with platinum resistance in ovarian cancer

项目总结 铂耐药是导致卵巢癌的最重要因素之一 复发和死亡率。在我们努力破译铂耐药的分子机制的过程中，我们 对耐铂的SK-OV3卵巢癌细胞系进行了全基因组筛选，鉴定出了Src-OV3 缺少C-末端调节性酪氨酸和N-末端肉豆蔻化位点的相关激酶(SRMS)为顶端 铂电阻调节器。进一步分析TCGA卵巢癌数据集显示，高 SRMS的表达对以铂为基础的治疗反应较差，总体存活率较差。自击倒以来 对P53基因缺陷的卵巢癌细胞株具有明显的增敏作用，但对铂的敏感性较小 在p53活性细胞系上，我们推测SRMS在p53缺失的铂耐药中起关键作用 卵巢癌。为了收集对SRMS在铂金阻力中作用的机制洞察力，我们展示了 SRMS可能通过直接磷酸化JNK来阻止JNK的激活。JNK信号通路很好 被确定为细胞毒剂引发的细胞凋亡的重要中介；我们观察到，SRMS是 P53基因缺失细胞对铂耐药的特异性研究表明：1)铂诱导细胞凋亡 因P53基因缺陷而导致JNK信号通路依赖的P53缺陷卵巢癌细胞 信号通路介导的细胞凋亡；以及2)SRMS对JNK信号的抑制减轻铂诱导的 从而促进P53基因缺失细胞的铂耐药。P53在高密度脂蛋白中一致缺乏。 恶性浆液性卵巢癌(HGSOC)。发现SRMS在P53-铂耐药中的显著作用 细胞缺乏提示SRMS可作为治疗HGSOC铂耐药的理想靶点。在……里面 我们的药物再利用筛选发现，B-RafV600E的选择性抑制剂PLX4720可以有效地 抑制SRMS活性。在这一应用中，我们提出了三个具体目标：1)表征分子机制 潜在的SRMS-授予铂金阻力；2)定义与铂金阻力相关的事件 受SRMS-JNK信号控制；以及3)研究靶向SRMS的潜力，以增强 白金疗法。这一应用的成功将揭示SRMS在 卵巢癌的铂耐药。重要的是，我们将评估以SRMS为目标的战略以克服 卵巢癌中的铂耐药。

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.