Activating Bax as a therapeutic strategy for lung cancer

描述（由申请人提供）：大多数人癌细胞对细胞凋亡具有抗性。细胞凋亡的主要调节因子是Bcl-2蛋白家族。一种新兴的癌症治疗策略是通过抑制抗凋亡Bcl-2蛋白的活性或促进促凋亡Bcl-2蛋白的功能来直接激活凋亡途径。然而，这些策略中的许多针对各种Bcl-2蛋白之间的相互作用，特别是促凋亡和抗凋亡Bcl-2蛋白之间的相互作用。由于Bcl-2蛋白之间的功能冗余，这些方法可能仅对有限的肿瘤类型有效或显示非特异性杀伤活性。Bax作为一种重要的促凋亡蛋白Bcl-2参与了肿瘤的发生发展，Bax的激活与肺肿瘤的凋亡有关。假定Bax单独足以在几乎所有凋亡范例中启动凋亡， 通过小分子化合物直接激活Bax可诱导表达Bax的肿瘤细胞死亡。我们的初步研究使用在大型化学库的计算机筛选identifiencya小分子预测结合到Bax疏水沟。该化合物能够激活Bax，导致Bax依赖性肿瘤细胞凋亡和抑制小鼠肿瘤生长。具体目的如下：1）研究Bax激活剂抑制小鼠肿瘤生长的机制。我们将测试Bax激活剂抑制小鼠中移植的人肿瘤以及自发性小鼠肺肿瘤生长的能力。此外，我们将研究活性化合物是否与其他治疗药物协同作用，以抑制肿瘤的生长。2)提高Bax激活剂激活Bax、诱导细胞凋亡和抑制肿瘤生长的能力。基于配体的分析将用于鉴定具有更大生物活性的潜在化合物，并对化合物进行实验检查。3)探讨Bax激活剂对生物膜的激活机制。我们将使用一种新的膜片钳技术结合生物化学和细胞生物学的方法来研究如何Bax激活剂诱导Bax渗透通道的天然生物膜在体外。我们还将研究Bax渗透孔的形成是如何由抗凋亡Bcl-2蛋白Bcl-XL调节的。由于Bax表达的失调与肺癌的发展有关，因此通过直接激活Bax诱导肿瘤细胞凋亡有望成为治疗肺癌患者的新治疗策略。

DESCRIPTION (provided by applicant): Most human cancer cells are resistant to apoptosis. Among the major regulators of apoptosis are the Bcl-2 family of proteins. An emerging cancer therapeutic strategy is directly activating the apoptotic pathways by inhibiting the activity of ani-apoptotic Bcl-2 proteins or promoting the function of pro-apoptotic Bcl-2 proteins. However, many of these strategies target the interaction among various Bcl-2 proteins, particularly the interaction between pro- apoptotic and anti-apoptotic Bcl-2 proteins. Due to functional redundancy among Bcl-2 proteins, these approaches are likely effective only on limited tumor types or display non-specific killing activities. As an important pro-apoptotic Bcl-2 protein, Bax s involved in the development of tumors, and Bax activation has been linked to apoptosis in lung tumors. Given that Bax alone is sufficient to initiate apoptosis in almost all apoptotic paradigms, direct activation of Bax by small molecule compounds could induce death of Bax-expressing tumor cells. Our preliminary studies using in silico screening of large chemical libraries identifid a small molecule predicted to bind to the Bax hydrophobic groove. This compound is able to activate Bax, leading to Bax-dependent tumor cell apoptosis and inhibition of mouse tumor growth. The following specific aims are proposed: 1) Examine the mechanisms by which the Bax activator inhibits tumor growth in mice. We will test the ability of the Bax activator to inhibt the growth of transplanted human tumors in mice as well as spontaneous mouse lung tumors. Furthermore, we will investigate whether the active compound acts synergistically with other therapeutic drugs to inhibit the growth of tumors. 2) Improve the ability of Bax activators to activate Bax, induce apoptosis and inhibit tumor growth. Ligand-based analyses will be used to identify potential compounds with greater biological activities and the compounds will be experimentally examined. 3) Investigate the mechanism of Bax activation on biological membranes by the Bax activators. We will use a novel patch-clamp technique combined with biochemical and cell biology approaches to investigate how the Bax activators induce Bax permeation channels on native biological membranes in vitro. We will also study how Bax permeation pore formation is regulated by the anti-apoptotic Bcl-2 protein Bcl-XL. As dysregulation of Bax expression has been implicated in lung tumor development, inducing apoptosis in tumor cells by directly activating Bax holds promise as a novel therapeutic strategy to treat lung cancer patients.