Targeting gain-of-function p53 and BCL-2 for small cell lung cancer treatment

项目摘要/摘要 通过一个独特的基因组学和药物筛选平台，拥有约800个实体肿瘤细胞系，我们发现了一个子集 的小细胞肺癌细胞系对FDA批准的bcl-2抑制剂ventoclax过敏。这些敏感的SCLC Bc1-2的表达水平始终较高。基于这一数据，万乃馨治疗小细胞肺癌的I/II期临床试验 患者已在VCU(NCT04543916)设计。最近有人提出小细胞肺癌可以被归类为 根据关键转录因子的表达分为四种亚型：SCLC-A(ASCL1阳性)、SCLC-N (NeuroD1阳性)、SCLC-P(POU2F3阳性)和SCLC-Y(YAP1阳性)。其中，SCLC-A和 SCLC-P约占SCLC的80%，经常高水平表达bcl2。我们注意到bcl2 我们检测的高敏感细胞系和万乃馨敏感细胞系均属于SCLC-A。然而，我们发现一个子集 SCLC-A和SCLC-P的bcl2高表达，但对万乃馨耐药。此外，这些中的大多数 小细胞肺癌细胞系有TP53错义突变，这会使单个氨基酸发生变化。这些变种人不是 不仅失去野生型p53抑癌功能，而且还获得了新的促癌活性。 函数(GOF)]。已有研究表明，GOF-P53的表达与肺癌的化疗和放射耐药有关。 各种癌症。此外，最近一项关于小细胞肺癌GOF P53基因敲入小鼠模型的研究表明，Gain- 功能失活可减弱化疗疗效。基于这些观察，我们假设 GoF-P53诱导耐药及同时抑制bc1-2和GOF-P53诱导 SCLC-A和SCLC-P的部分亚群具有协同抗癌活性。我们的初步数据支持这一假设： (1)GOF P53的下调增加了BH3-Only促凋亡的BIM的表达，并对 (2)HSP90抑制剂ganetespib靶向GOF P53可增加BIM的表达 并在SCLC-P和SCLC-A细胞中对万乃馨增敏。虽然目前有很多组合 对文奈德的研究提出了同时靶向bcl-2和GOF-p53的概念是创新的， 联合应用万乃馨和HSP90抑制剂有望成为治疗小细胞肺癌的有效方法。在这 建议，我们将在体外确定这种组合的作用机制和疗效 使用细胞系异种移植和患者来源的异种移植联合应用SCLC-A和SCLC-P亚型 (PDX)型号。目的1确定万乃馨和格奈替派诱导细胞死亡的机制。 联合应用于体外培养的小细胞肺癌细胞系。目标2将确定万乃馨和格奈替比联用的疗效 小鼠小细胞肺癌模型的治疗。由于万乃馨是FDA批准的，HSP90抑制剂正在 在包括小细胞肺癌在内的临床试验中进行了调查，拟议项目的成功完成将导致 在弗吉尼亚州立大学梅西癌症中心和退伍军人管理局霍姆斯·亨特医学中心开展临床试验。

Project Summary/Abstract Through a unique genomics and drug screening platform with ~800 solid tumor cell lines, we have found a subset of SCLC cell lines are hypersensitive to venetoclax, an FDA-approved inhibitor of BCL-2. These sensitive SCLCs have invariably high BCL-2 expression. Based on this data, a phase I/II clinical trial with venetoclax in SCLC patients has been designed at VCU (NCT04543916). It has been recently proposed that SCLC can be classified in four subtypes based on the expression of key transcription factors: SCLC-A (ASCL1 positive), SCLC-N (NeuroD1 positive), SCLC-P (POU2F3 positive), and SCLC-Y (YAP1 positive). Among them, SCLC-A and SCLC-P, which make up almost 80% of SCLC, frequently express high levels of BCL-2. We noticed that BCL-2 high and venetoclax-sensitive cell lines that we examined all belong to SCLC-A. However, we found that a subset of SCLC-A and SCLC-P showed high BCL-2 expression but were venetoclax-resistant. In addition, most of these SCLC cell lines have TP53 missense mutations, which make a single amino acid change. These mutants not only lose wild-type p53 tumor suppressor functions, but also acquire novel cancer-promoting activities [gain-of- function (GOF)]. It has been shown that GOF p53 expression is associated with chemo- and radio-resistance in a variety of cancers. Furthermore, a recent study with GOF p53 knock-in mouse models of SCLC suggests gain- of-function activity can attenuate chemotherapeutic efficacy. Based on these observations, we hypothesize that GOF p53 confers venetoclax-resistance and that simultaneous inhibition of BCL-2 and GOF p53 induces synergistic anticancer activity in a subset of SCLC-A and SCLC-P. Our preliminary data support this hypothesis: (1) Down-regulation of GOF p53 increases the expression of a BH3-only pro-apoptotic BIM and sensitizes to venetoclax in SCLC-P cells; (2) targeting GOF p53 by the HSP90 inhibitor, ganetespib, increases BIM expression and sensitizes to venetoclax in SCLC-P and SCLC-A cells. Although currently there are many combination studies for venetoclax proposed, the concept of simultaneous targeting of BCL-2 and GOF p53 is innovative and the combination of venetoclax and HSP90 inhibitors would be promising approach for SCLC treatment. In this proposal, we will determine the mechanism of action of this combination in vitro and the efficacy of this combination in a subset of SCLC-A and SCLC-P subtypes using cell line xenograft and patient-derived xenograft (PDX) models. Aim 1 will determine the mechanisms of cell death induced by venetoclax and ganetespib combination in SCLC cell lines in vitro. Aim 2 will define the efficacy of venetoclax and ganetespib combination treatment in mouse models of SCLC. Since venetoclax is FDA-approved and HSP90 inhibitors are being investigated in clinical trials including SCLC, the successful completion of the proposed project will lead to developing clinical trials at VCU Massey Cancer Center and Holmes Hunter VA Medical Center.