One of the hallmarks of cancer cells is their failure to respond to the cellular mechanism of apoptosis. The B-cell lymphoma 2 (BCL-2) family of proteins regulate apoptosis. Their ability to do so can be measured using several methods that in turn anticipate the fate of the cancer cell in response to apoptosis-inducing treatment. These assays ultimately identify the readiness of the cancer cell to undergo apoptosis, which is referred to as the mitochondrial priming state. These metrics, however, have been challenging to implement in the clinic.Methods: Here, we describe a unique method that relies on a panel of novel conformation-specific antibodies (termed PRIMAB) that can directly measure the mitochondrial priming state. These reagents are highly specific for complexes of their corresponding pro-survival protein interactions with the pro-apoptotic protein BIM. These BIM-containing heterodimeric complexes have long been established as hallmarks of primed cancer cells.Results: Using clinically amenable assay formats, PRIMABs were shown to detect the presence of these anti-apoptotic–pro-apoptotic complexes and their disruption by BH3-mimetic drugs. Moreover, PRIMABs were able to detect a shift in priming status following BH3-mimetic treatment, a factor associated with resistance to these drugs. In a panel of AML patient samples, we report a wide range of priming levels for each PRIMAB complex, demonstrating the potential for heterogeneity in responses. We also show that PRIMABs could be predictive of outcomes for AML patients following cytarabine-based treatment.Conclusions: PRIMABs provide novel and useful tools for cancer research and for clinical implementation as reagents providing predictive tests for treatment response.
癌细胞的一个显著特征是其对细胞凋亡机制的无反应性。B细胞淋巴瘤2（BCL-2）蛋白家族调控细胞凋亡过程。其调控能力可通过多种方法进行检测，这些方法进而能够预测癌细胞在凋亡诱导治疗下的命运。这些检测手段最终可识别癌细胞发生凋亡的准备状态，即线粒体启动状态。然而，这些评估指标在临床应用中一直面临挑战。 方法：本研究描述了一种独特的方法，该方法基于一组新型构象特异性抗体（命名为PRIMAB），可直接测量线粒体启动状态。这些试剂对其对应的促存活蛋白与促凋亡蛋白BIM形成的复合物具有高度特异性。长期以来，这些含BIM的异源二聚体复合物已被确认为启动状态癌细胞的标志物。 结果：通过临床适用的检测形式，PRIMABs被证明能够检测这些抗凋亡-促凋亡复合物的存在及其被BH3模拟药物破坏的情况。此外，PRIMABs能够检测BH3模拟药物治疗后启动状态的转变，这种转变与药物耐药性相关。在一组急性髓系白血病患者样本中，我们观察到每种PRIMAB复合物的启动水平存在广泛差异，表明治疗反应可能存在异质性。我们还证明PRIMABs能够预测急性髓系白血病患者接受阿糖胞苷治疗后的临床结局。 结论：PRIMABs为癌症研究和临床实践提供了新颖有效的工具，可作为预测治疗反应的检测试剂。
肿瘤(癌症)患者之家