Structure-based anti-cancer drug development

描述（由申请人提供）：肺癌是癌症相关死亡的主要原因，大多数肺癌患者由于化疗耐药而预后不良。开发更有效的新药，通过基本的分子机制，包括细胞凋亡，克服化疗耐药性，对改善肺癌患者的预后至关重要。Bcl 2是一种主要的抗凋亡分子，在小细胞肺癌（SCLC）和非小细胞肺癌（NSCLC）细胞中广泛表达。肺癌化疗耐药的一个主要因素是Bcl 2的过表达，这表明Bcl 2可能是一个有吸引力的治疗靶点。Bcl 2的BH 4结构域包含两亲性α 1-螺旋，已被证明是Bcl 2抗凋亡功能所需的结构域。因此，我们选择BH 4结构域作为对接位点，使用计算机化的DOCK程序和来自美国国家癌症研究所（NCI）的数据库来筛选可能与Bcl 2结合的小分子。从NCI获得了200种确定具有最高亲和力的化合物，并测试了它们对细胞死亡的影响。已发现200种化合物中的4种有效诱导各种人肺癌细胞的凋亡。我们将这些化合物命名为小分子Bcl 2抑制剂（SMBI-1~4）。有趣的是，SMBI-1~4对正常小气道上皮细胞的凋亡作用显著低于肺癌细胞，表明这些化合物对肿瘤细胞的选择性。在NSCLC动物模型中，先导SMBI有效抑制肿瘤生长，并增加肿瘤组织中的细胞凋亡。这些初步研究结果表明，SMBI（s）可能具有很大的潜力，被开发为一类新的抗肺癌药物。调节mTOR通路正在临床上开发为肺癌治疗的高级策略。然而，Bcl 2的表达与肺癌细胞对mTOR抑制剂的抗性相关。因此，增强肺癌细胞对mTOR抑制的敏感性的有效方法是将mTOR抑制剂与Bcl 2抑制剂（即SMBI）组合联合收割机。我们的初步数据显示，SMBI和雷帕霉素的组合治疗肺癌细胞不仅协同诱导细胞凋亡，而且增强生长抑制，这表明组合的mTOR和Bcl 2抑制可以相加地抑制肺肿瘤生长，导致体内持续消退。为了严格检验这些假设，我们确定了两个具体目标：（1）确定SMBI诱导人肺癌细胞凋亡的机制;（2）确定SMBI是否抑制SCLC和NSCLC异种移植物中的肿瘤生长。研究将评估通过SMBI和mTOR抑制剂的组合共靶向Bcl 2和mTOR是否协同改善体内抗肺癌功效。从结果来看，预期通过共靶向Bcl 2和mTOR将开发出一类新的抗癌药物和更有效的癌症治疗方法。 公共卫生相关性： 大多数肺癌患者由于化疗耐药而预后不良。开发更有效的新药，通过基本的分子机制来克服化疗耐药性，对改善肺癌患者的预后至关重要。本研究旨在开发小分子抗肺癌药物，抑制肺癌细胞中Bcl 2的抗凋亡功能。

DESCRIPTION (provided by applicant): Lung cancer is the leading cause of cancer-related mortality and most patients with lung cancer have poor prognosis due to chemoresistance. Development of more effective, new drugs that act through basic molecular mechanisms, including apoptosis, to overcome chemoresistance is critical to improve the prognosis of patients with lung cancer. Bcl2, a major antiapoptotic molecule, is extensively expressed in both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) cells. One major factor implicated in the resistance to chemotherapy is the overexpression of Bcl2, suggesting that Bcl2 should be an attractive therapeutic target in human lung cancer. The BH4 domain of Bcl2, which encompasses an amphipathic a1-helix, has been demonstrated to be a required domain for Bcl2's antiapoptotic function. Therefore, we chose the BH4 domain as a docking site for screening of small molecules that may inactivate Bcl2 using the computerized DOCK program and a database from the National Cancer Institute (NCI). Two hundred of the compounds determined to have the highest affinity were obtained from the NCI and tested for their effects on cell death. Four of the two hundred compounds have been found to potently induce apoptosis of various human lung cancer cells. We named these compounds as small molecule Bcl2 inhibitors (i.e. SMBI-1~4). Intriguingly, SMBI-1~4 represent significantly less apoptotic effect on normal small airway epithelial cells as compared to lung cancer cells, indicating a selectivity of these compounds for tumor cells. The lead SMBI potently represses tumor growth in association with increased apoptosis in tumor tissues in NSCLC animal models. These preliminary findings suggest that SMBI(s) may have great potential to be developed as a new class of anti-lung cancer drugs. Modulation of the mTOR pathway is being clinically developed as an advanced strategy for lung cancer treatment. However, expression of Bcl2 is associated with resistance of lung cancer cells to mTOR inhibitor(s). Thus, an effective way to enhance the sensitivity of lung cancer cells to mTOR inhibition is to combine a mTOR inhibitor with a Bcl2 inhibitor (i.e. SMBI). Our preliminary data reveal that treatment of lung cancer cells with a combination of SMBI and rapamycin not only synergistically induces apoptosis but also augments growth inhibition, suggesting that the combined mTOR and Bcl2 inhibition may additively suppress lung tumor growth, leading to sustained regression in vivo. To critically test these hypotheses, we have identified two specific aims: (1) To determine the mechanism(s) by which SMBI(s) induces apoptosis in human lung cancer cells; (2) To determine whether SMBI(s) represses tumor growth in both SCLC and NSCLC xenografts. Studies will evaluate whether co-targeting Bcl2 and mTOR by a combination of SMBI and a mTOR inhibitor synergistically improves the anti-lung cancer efficacy in vivo. From the results, it is expected that a new class of anti-cancer drugs and a more effective approach for cancer treatment will be developed by co-targeting Bcl2 and mTOR. PUBLIC HEALTH RELEVANCE: Project Narrative Most patients with lung cancer have a poor prognosis due to chemoresistance. Development of more effective new drugs that act through basic molecular mechanisms to overcome chemoresistance is critical to improve the prognosis of patients with lung cancer. Studies in this proposal are designed to develop small molecules as novel anti-lung cancer drugs that inhibit the antiapoptotic function of Bcl2 in lung cancer cells.