Cancer cells have differential metabolic dependencies compared to their nonmalignant counterparts. However, few metabolism-targeting compounds have been successful in clinical trials. Here, we investigated the metabolic vulnerabilities of triple-negative breast cancer (TNBC), particularly those metabolic perturbations that increased mitochondrial apoptotic priming and sensitivity to BH3 mimetics (drugs that antagonize antiapoptotic proteins). We used high-throughput dynamic BH3 profiling (HT-DBP) to screen a library of metabolism-perturbing small molecules, which revealed inhibitors of the enzyme nicotinamide phosphoribosyltransferase (NAMPT) as top candidates. In some TNBC cells but not in nonmalignant cells, NAMPT inhibitors increased overall apoptotic priming and induced dependencies on specific antiapoptotic BCL-2 family members. Treatment of TNBC cells with NAMPT inhibitors sensitized them to subsequent treatment with BH3 mimetics. The combination of a NAMPT inhibitor (FK866) and an MCL-1 antagonist (S63845) reduced tumor growth in a TNBC patient–derived xenograft model in vivo. We found that NAMPT inhibition reduced NAD⁺ concentrations below a critical threshold that resulted in depletion of adenine, which was the metabolic trigger that primed TNBC cells for apoptosis. These findings demonstrate a close interaction between metabolic and mitochondrial apoptotic signaling pathways and reveal that exploitation of a tumor-specific metabolic vulnerability can sensitize some TNBC to BH3 mimetics.

与非恶性细胞相比，癌细胞具有不同的代谢依赖性。然而，很少有代谢靶向化合物在临床试验中取得成功。在这里，我们研究了三阴性乳腺癌 (TNBC) 的代谢脆弱性，特别是那些增加线粒体凋亡启动和对 BH3 模拟物（拮抗抗凋亡蛋白的药物）敏感性的代谢扰动。我们使用高通量动态 BH3 分析 (HT-DBP) 来筛选干扰代谢的小分子文库，该文库揭示了烟酰胺磷酸核糖基转移酶 (NAMPT) 的抑制剂作为最佳候选者。在一些 TNBC 细胞中，但在非恶性细胞中，NAMPT 抑制剂增加了整体凋亡启动并诱导了对特定抗凋亡 BCL-2 家族成员的依赖性。用 NAMPT 抑制剂处理 TNBC 细胞使它们对随后的 BH3 模拟物处理敏感。NAMPT 抑制剂 (FK866) 和 MCL-1 拮抗剂 (S63845) 的组合减少了 TNBC 患者衍生的体内异种移植模型中的肿瘤生长。我们发现 NAMPT 抑制降低了 NAD⁺浓度低于导致腺嘌呤消耗的临界阈值，腺嘌呤是引发 TNBC 细胞凋亡的代谢触发因素。这些发现证明了代谢和线粒体凋亡信号通路之间的密切相互作用，并揭示了利用肿瘤特异性代谢脆弱性可以使一些 TNBC 对 BH3 模拟物敏感。