High-dose acetaminophen (AAP) withN-acetylcysteine (NAC) rescue is among the few treatments that has shown activity in phase I trials without achieving dose-limiting toxicity that has not progressed to evaluation in later line studies. While the anti-tumor effects of AAP/NAC appear not to be mediated by glutathione depletion and free radical injury, the mechanism of anti-tumor effects of AAP/NAC has not been definitively characterized. In vitro, the effects of AAP/NAC were evaluated on bone marrow derived macrophages. Effects of AAP on IL-4/STAT6 (M2) or IFN/LPS/STAT1 (M1) signaling and downstream gene and protein expression were studied. NAC reversed the AAP toxicity in the normal liver but did not reverse AAP cytotoxicity against tumor cells in vitro. AAP/NAC selectively inhibited IL-4-induced STAT6 phosphorylation but not IFN/LPS-induced STAT1 phosphorylation. Downstream, AAP/NAC inhibited IL-4 induction of M2-associated genes and proteins but did not inhibit the IFN/LPS induction of M1-associated genes and proteins. In vivo, AAP/NAC inhibited tumor growth in EF43.fgf4 and 4T1 triple-negative breast tumors. Flow cytometry of tumor-associated macrophages revealed that AAP/NAC selectively inhibited M2 polarization. The anti-tumor activity of high-dose AAP/NAC is lost in macrophage-depleted mouse syngeneic tumor models, suggesting a macrophage-dependent mechanism of action. In conclusion, our study is the first to show that high-dose AAP/NAC has profound effects on the tumor immune microenvironment that facilitates immune-mediated inhibition of tumor growth.
大剂量对乙酰氨基酚（AAP）联合N-乙酰半胱氨酸（NAC）解救疗法，是少数在Ⅰ期临床试验中显示出活性且未达到剂量限制性毒性，但尚未进入后续临床阶段评估的治疗方案之一。尽管AAP/NAC的抗肿瘤效应似乎并非通过谷胱甘肽耗竭和自由基损伤介导，但其抗肿瘤作用机制尚未明确阐明。在体外实验中，我们评估了AAP/NAC对骨髓源性巨噬细胞的影响，研究了AAP对IL-4/STAT6（M2型）或IFN/LPS/STAT1（M1型）信号通路及其下游基因与蛋白表达的作用。NAC能逆转AAP对正常肝脏的毒性，但在体外实验中并未逆转AAP对肿瘤细胞的细胞毒性。AAP/NAC选择性抑制IL-4诱导的STAT6磷酸化，但不影响IFN/LPS诱导的STAT1磷酸化。在下游通路中，AAP/NAC抑制IL-4诱导的M2型相关基因和蛋白表达，但不抑制IFN/LPS诱导的M1型相关基因和蛋白表达。在体内实验中，AAP/NAC能抑制EF43.fgf4和4T1三阴性乳腺癌肿瘤的生长。通过肿瘤相关巨噬细胞的流式细胞术分析发现，AAP/NAC选择性抑制M2型极化。在巨噬细胞缺失的小鼠同系肿瘤模型中，大剂量AAP/NAC的抗肿瘤活性消失，提示其作用机制依赖于巨噬细胞。总之，本研究首次揭示大剂量AAP/NAC能显著影响肿瘤免疫微环境，从而促进免疫介导的肿瘤生长抑制。
肿瘤(癌症)患者之家