pBACH1 binding site on BRCT(BRCA1): A novel approach to cancer therapeutics

描述（由申请人提供）：乳腺癌基因1 （BRCA1）编码1863氨基酸蛋白。BRCA1的c端结构域（BRCT）与多种其他蛋白质相互作用，促进细胞功能，如检查点调节，DNA损伤反应和DNA修复。在BRCA1的BRCT结构域中发现的突变导致乳房和卵巢组织中肿瘤的形成。这些基因突变使女性易患乳腺癌和卵巢癌。然而，回顾性临床研究表明，BRCT结构域突变的患者对化疗的反应更好。M1775R是在BRCA1的BRCT结构域中发现的致癌突变。由M1775R突变蛋白引起的癌症的分子基础归因于BRCTM1775R与磷酸化蛋白（如羧基解旋酶BACH1 (pBACH1)）的结合缺失。生化和临床前研究表明，BRCT- pbach1相互作用对于检查点调节和DNA修复至关重要，携带BRCT突变体的细胞对DNA损伤化疗药物敏感。综上所述，这些研究表明，由于BRCT DNA修复功能的丧失，具有BRCT突变的癌症对治疗的反应更好。通过结合无细胞和基于细胞的检测，我们鉴定出BRCT-pBACH1相互作用的小分子抑制剂（BI-94）。我们还发现BI-94对依托泊苷和博莱霉素诱导的乳腺癌细胞生长抑制和凋亡有增敏作用。在本申请中，我们建议通过以下方式继续这些研究：1)探索BRCT-pBACH1相互作用对博莱霉素/依托泊苷治疗的耐药是否在特定目标1中扩展到其他乳腺癌和卵巢癌治疗药物；2)通过特定目标2-4推进BI-94 /或其相近类似物作为抗癌药物。在这个应用中，我们建议开发蛋白质-蛋白质相互作用的小分子抑制剂。该项目的成功完成将1)为了解BRCA1突变引起的癌症的发生和进展提供有价值的工具；2)提供先导化合物，可作为化疗药物开发用于治疗散发性乳腺癌和卵巢癌患者。

DESCRIPTION (provided by applicant): BReast CAncer gene 1 (BRCA1) encodes for an 1863 amino acid protein. The C-terminus domains of BRCA1 (BRCT) interact with a variety of other proteins to facilitate cellular functions such as checkpoint regulation, DNA damage response and DNA repair. Mutations found in the BRCT domains of BRCA1, result in the formation of tumors in the breast and ovarian tissues. These mutations genetically predispose women to breast and ovarian cancers. However, retrospective clinical studies show that patients with mutations in the BRCT domains respond better to chemotherapy. M1775R is a cancer causing mutation found in the BRCT domains of BRCA1. The molecular basis for the cancer caused by the M1775R mutant protein has been attributed to the loss of BRCTM1775R binding to phosphorylated proteins, such as the carboxy helicase BACH1 (pBACH1). Biochemical and preclinical studies have shown that the BRCT-pBACH1 interaction is essential for check point regulation and DNA repair and cells carrying BRCT mutants are sensitive to DNA damaging chemotherapeutic agents. Taken together, these studies indicate that cancers with the BRCT mutations respond better to therapy due to the loss of BRCT DNA repair function. Using a combination of cell-free and cell-based assay we identified a small molecule inhibitor (BI-94) of the BRCT-pBACH1 interaction. We also show that BI-94 sensitizes breast cancer cells to growth inhibition and apoptosis induced by Etoposide and Bleomycin. In this application, we propose to continue these studies by 1) exploring if the resistance induced by the BRCT-pBACH1 interaction towards Bleomycin / Etoposide treatment extends to other breast and ovarian cancer therapeutics in specific aim 1 and 2) advance BI-94 / or a close analog as an anti-cancer agent through specific aims 2-4.PROJECT NARRATIVE In this application we propose to develop small molecule inhibitors of protein-protein interaction. The successful completion of this project will 1) provide valuable tools to understand the genesis and progression of cancers due to BRCA1 mutation and 2) provide lead compounds that can be developed as chemotherapeutic agents to treat sporadic breast and ovarian cancer patients.