Reading mitochondrial apoptotic signaling to identify active cancer therapeutics

摘要 我是一名肿瘤学家和癌症生物学家，负责监督一家实验室，专注于识别 选择性地诱导癌细胞的凋亡。我最初对细胞凋亡领域的贡献来自于分离 某些促死亡的bc1-2家族BH3-Only蛋白在促凋亡的基础上转化为“敏感剂”和“激活剂” 功能。这一发现激发了我对用模仿的药物抑制bcl2功能的可能性的兴趣 促凋亡蛋白的BH3结构域。我设计了第一个小鼠模型，证明了 BCL-2功能本身就足以使癌症得到缓解。在此之后，我设计了一个工具 称为BH3图谱-将线粒体暴露于基于两亲性α-多肽的合成寡肽- 促凋亡蛋白的螺旋BH3结构域与线粒体外膜通透性的测定 (MOMP)。通过使用某些选择性相互作用的BH3多肽，我可以使用BH3图谱来识别 对BH3抑制特别敏感。我使用BH3分析来帮助启动临床试验计划 Bcl-2抑制剂在几种疾病中的应用。到目前为止，这些项目中最成功的是 慢性淋巴细胞白血病和急性髓系白血病，前者已经产生FDA 批准。 使用不同的BH3多肽，BH3图谱可以测量整体的凋亡启动，或接近阈值 对细胞凋亡的影响。我们利用这一方面来证明，差异的凋亡启动可能是最 化疗成功与否的重要决定因素。此外，差异的凋亡启动是 常规化疗有一个治疗指标的主要原因--最非恶性体细胞 与化疗敏感的癌细胞相比，细胞对凋亡的准备要小得多。基于这一发现，我们询问了 我们是否能找到可以选择性地增强癌细胞中的凋亡启动的药物。我们发现 我们可以在将癌细胞暴露于有效药物后的数小时内测量到细胞凋亡率的增加 使用动态BH3分析(DBP)。启动增加的衡量标准是线粒体敏感性的增加。 经BH3多肽处理的细胞与未处理的对照组进行比较。在过去的几年里，我们发现一个 在人类和小鼠模型中，药物在DBP中的启动增加是体内活动的一个很好的预测指标 实体和液体肿瘤。与大多数其他体外药物敏感策略相比，DBP的一个重要优势是 DBP需要不超过24小时的体外培养。这克服了将军面临的主要障碍。 应用这种策略，因为许多癌症不能适应长期的体外培养，如果他们适应了， 它们的表型会发生改变，从而降低它们所能提供的信息。我们正在探索DBP作为一种 许多液体和固体肿瘤的发现工具和预测生物标记物。此外，我们正在将其作为一种工具来 确定可以使靶肿瘤细胞对免疫肿瘤疗法更敏感的药物。

Summary I am an oncologist and cancer biologist supervising a laboratory focused on identifying therapies that selectively induce apoptosis in cancer cells. My initial contributions to the apoptosis field came with separating certain pro-death BCL-2 family BH3-only proteins into “sensitizers” and “activators” based on pro-apoptotic function. This finding drove my interest in the possibilities of inhibiting BCL-2 function with drugs that mimicked the BH3 domain of pro-apoptotic proteins. I designed the first mouse model that demonstrated that loss of BCL-2 function by itself could be sufficient to drive a cancer into remission. Following this, I designed a tool called BH3 profiling – exposing mitochondria to synthetic oligo-peptides based on the amphipathic alpha- helical BH3 domains of proapoptotic proteins and measuring mitochondrial outer membrane permeabilization (MOMP). By using certain selectively-interacting BH3 peptides, I could use BH3 profiling to identify cells that were especially sensitive to BH3 inhibition. I used BH3 profiling to help launch clinical trial programs of the BCL-2 inhibitor venetoclax in several diseases. Most successful among these so far have been programs in chronic lymphocytic leukemia and acute myelogenous leukemia, the former of which has already yielded FDA approvals. Using different BH3 peptides, BH3 profiling can measure overall apoptotic priming, or proximity to the threshold of apoptosis. We used this aspect to demonstrate that differential apoptotic priming is perhaps the most significant determinant of successful chemotherapy treatment. Moreover, differential apoptotic priming is the main reason that there is a therapeutic index for conventional chemotherapy – most non-malignant somatic cells are far less primed for apoptosis than chemosensitive cancer cells. Building on this finding, we asked whether we could identify drugs that could enhance apoptotic priming selectively in cancer cells. We found that we could measure increased apoptotic priming within hours of exposing cancer cells to effective drugs using dynamic BH3 profiling (DBP). Increased priming is measured as increased sensitivity of mitochondria in treated cells to BH3 peptides compared to untreated controls. Over the past few years, we have found that an increased priming by a drug in DBP is an excellent predictor of in vivo activity in human and mouse models, in solid and liquid tumors. An important advantage of DBP over most other ex vivo drug sensitivity strategies is that DBP requires no more than 24 hours of ex vivo culture. This overcomes the major obstacle to the general application of such strategies, since many cancers cannot adapt to long-term ex vivo culture, and if they do, they are phenotypically altered so as to degrade the information they can provide. We are exploring DBP as a discovery tool and predictive biomarker in many liquid and solid tumors. Moreover, we are using it as a tool to identify drugs that can make target tumor cells more sensitive to immuno-oncology therapies.