A small molecule, α-(trichloromethyl)-4-pyridineethanol (PETCM), was identified by high-throughput screening as an activator of caspase-3 in extracts of a panel of cancer cells. PETCM was used in combination with biochemical fractionation to identify a pathway that regulates mitochondria-initiated caspase activation. This pathway consists of tumor suppressor putative HLA-DR–associated proteins (PHAP) and oncoprotein prothymosin-α (ProT). PHAP proteins promoted caspase-9 activation after apoptosome formation, whereas ProT negatively regulated caspase-9 activation by inhibiting apoptosome formation. PETCM relieved ProT inhibition and allowed apoptosome formation at a physiological concentration of deoxyadenosine triphosphate. Elimination of ProT expression by RNA interference sensitized cells to ultraviolet irradiation–induced apoptosis and negated the requirement of PETCM for caspase activation. Thus, this chemical-biological combinatory approach has revealed the regulatory roles of oncoprotein ProT and tumor suppressor PHAP in apoptosis.

中文翻译：

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PHAP 蛋白和胸腺素原-α 在死亡调节途径中的独特作用

一种小分子 α-(三氯甲基)-4-吡啶乙醇 (PETCM) 通过高通量筛选被鉴定为一组癌细胞提取物中 caspase-3 的激活剂。PETCM 与生化分离结合使用，以确定调节线粒体启动的半胱天冬酶激活的途径。该通路由肿瘤抑制因子推定的 HLA-DR 相关蛋白 (PHAP) 和癌蛋白胸腺素原-α (ProT) 组成。PHAP 蛋白在凋亡体形成后促进 caspase-9 活化，而 ProT 通过抑制凋亡体形成负向调节 caspase-9 活化。PETCM 解除 ProT 抑制并允许在生理浓度的脱氧腺苷三磷酸下形成凋亡体。通过 RNA 干扰消除 ProT 表达使细胞对紫外线照射诱导的细胞凋亡敏感，并消除了 PETCM 对半胱天冬酶激活的要求。因此，这种化学-生物组合方法揭示了癌蛋白 ProT 和肿瘤抑制因子 PHAP 在细胞凋亡中的调节作用。