CREBBP突变预测卵巢癌复发及其个性化治疗方案

Ovarian cancer is the leading cause of death from gynecological malignancy in China. Most deaths are from advanced-stage, high-grade serous ovarian cancer (HGS-OvCa). The 5-year survival rate is only 31% and novel approaches are needed to identify new therapeutic targets. Recently, we identified CREBBP (CBP) as a novel driver gene significantly mutated in 6% of HGS-OvCa. Others reported 18.3% of relapse acute lymphoblastic leukaemia, 25% of Diffuse large B-cell lymphoma, 15% of small cell lung cancer and 10% of squamous cell lung cancer had CBP mutations. CBP encodes the transcriptional coactivator and histone acetyltransferase CREB-binding protein. We further discovered a unique molecular subtype of HGS-OvCA characterized with somatically acquired mutations or deletions in CBP that are significantly associated with increased disease recurrence and poor prognosis. We found some mutations in CBP impair acetylation activity of TP53, BCL6 and histone proteins. To translate our recent discovery into the clinic, we propose to determine the mechanisms by which CBP contributes to relapse in HGS-OvCa and to develop the new combination therapy strategy for ovarian cancer with inactivating mutations in CBP. Our long-term goal is to understand how CBP and its downstream effectors can be used as prognostic biomarkers and therapeutic targets, with the ultimate goal to improve outcomes of women with HGS-OvCa. Our central hypothesis is that CBP normally acts as a tumor suppressor, and that mutations found in ovarian cancer cause loss of function mostly associated with loss of acetyltransferase activity; sequential treatment with histone deacethylation (HDAC) inhibitors and platinum drugs can inhibit the growth of cancer cells with aberrations in CBP. To test this hypothesis, we propose to accomplish the following aims. Aim 1 will systematically characterize somatic mutations in CREBBP and further validate their association with poor outcome of patients with HGS-OvCa in China. Aim 2 will determine the biological role of CBP on ovarian cancer cell proliferation, migration/invasion and apoptosis. Assays will be performed in ovarian cancer cell lines which over-express wild-type and mutant cDNA of CBP that are effectively CBP null. The effects of aberrant CBP on tumorigenicity will also be tested in NOD-SCID mice. Aim 3 will test the synergized effects of HDAC inhibitors and platinum drugs in inhibiting the growth of cancer cells with aberrations in CBP in vitro & in vivo. The proposed experiments will uncover novel roles for CBP in ovarian cancer development and potential combination therapy strategy for ovarian carcinoma with aberrant CBP. These results will also provide a rational basis for the potential use of HDAC inhibitors to restore normal levels of protein acetylation in the treatment of HGS-OvCa. Our study supports the personalized medicine approach for treating cancer and the increasing drive to translate laboratory-based findings into clinical utility.

卵巢癌是妇科癌死亡的首要原因，多数死亡由高度恶性浆液性卵巢癌（HGS-OVCA）引起，5年生存率仅为31％，因此需要新的治疗靶点。我们发现一个新驱动基因CREBBP（CBP）在HGS-OVCA中有显著突变，且其突变与疾病复发和预后差有关。CBP编码转录共激活因子和组蛋白乙酰转移酶CREB结合蛋白，某些突变影响TP53，BCL6和组蛋白的乙酰化活性。本研究将鉴定CBP在HGS-OVCA的复发中的作用机制和发展针对携带CBP失活突变的HGS-OVCA的新联合治疗策略。我们假设正常情况下CBP是肿瘤抑制基因；卵巢癌中的CBP突变会引起功能缺失且多与乙酰转移酶活性丧失有关；组蛋白去乙酰化酶抑制剂（HDACi）和铂类药物联合序贯疗法能够抑制CBP突变的肿瘤细胞生长。我们将通过细胞学，分子生物学和动物实验来验证这一假设。实验结果将为利用HDACi恢复蛋白质乙酰化水平治疗HGS-OVCA提供理论基础。

卵巢癌是妇科癌死亡的首要原因，多数死亡由高度恶性浆液性卵巢癌（HGS-OVCA）引起，5 年生存率仅为 31％，因此需要新的治疗靶点。我们前期研究发现一个新驱动基因 CREBBP（CBP）在 HGS-OVCA 中有显著突变，且其突变与疾病复发和预后差有关。CBP 编码转录共激活因子和组蛋白乙酰转移酶 CREB 结合蛋白，某些突变影响 TP53，BCL6 和组蛋白的乙酰化活性。本研究项目的目标是鉴定 CBP 在 HGS-OVCA 的复发中的作用机制和发展针对携带 CBP 失活突变的 HGS-OVCA 的新联合治疗策略。利用目标序列捕获测序对300 名 HGS-OVCA 患者CBP 的所有编码外显子和每个外显子两端至少10 bp 的内含子进行目标区域重测序分析，发现了14个CBP 突变，包括2个frameshift/truncation、3个missense、4个silence和5个intronic突变。Cox比例风险模型分析发现CBP突变与无复发生存率有显著相关，携带这些体细胞异常的病人预后差。通过大量细胞学体外试验和小鼠体内试验，表明抑制CBP的表达对卵巢癌细胞增殖起抑制作用，出现细胞周期、细胞迁移、与上皮细胞间质转化相关分子表达以及细胞凋亡等改变；卵巢癌细胞迁移受抑可能与CBP影响了SOX4的转录有关；干扰CBP基因表达后能促进凋亡和提高顺铂敏感性，与促进caspase的活化有关。CBP特异性抑制剂ICG-001能够抑制卵巢癌细胞的增殖和促进卵巢癌细胞对顺铂的敏感性。实验结果将为利用CBP特异性抑制剂治疗 HGS-OVCA 提供理论基础。