Tocilizumab inhibits IL-6-JAK-STAT3 signaling to reverse bone marrow stromal cell-mediated AML chemotherapy resistance

AimTo study tocilizumab (TCZ)-mediated reversal of chemotherapy resistance in acute myeloid leukemia (AML) cells by blocking the IL-6/JAK/STAT3 signaling pathway in the bone marrow microenvironment.MethodsAn in vitro co-culture system was established using AML cell lines (U937 and HL-60) and HS-5 bone marrow stromal cells, followed by assessment of IL-6/JAK/STAT3 signaling pathway activation through Western blot. Subsequent experiments utilized IL-6-knockdown HS-5 cells and TCZ to target this pathway in co-cultured AML cells, with drug sensitivity to Ara-C assessed by CCK-8 and AnnexinVAPC/7-AAD assays. In vivo validation was performed using AML xenograft models to evaluate TCZ's synergistic effect with Ara-C.ResultsIn an adhesion coculture system, IL-6 secreted by HS-5 cells activated the STAT3 signaling pathway in AML cells. This activation was effectively suppressed by either IL-6 knockdown or TCZ treatment, which inhibited JAK2/STAT3 phosphorylation. Consistently, TCZ treatment significantly sensitized AML cells to Ara-C chemotherapy in both in vitro and in vivo settings.ConclusionTCZ enhances AML cell sensitivity to Ara-C by targeting the IL-6/JAK/STAT3 signaling pathway.

研究目的：本研究旨在探究托珠单抗（tocilizumab, TCZ）通过阻断骨髓微环境中的IL-6/JAK/STAT3信号通路，逆转急性髓系白血病（acute myeloid leukemia, AML）细胞化疗耐药性的作用机制。
实验方法：本研究首先采用AML细胞系（U937、HL-60）与HS-5骨髓基质细胞构建体外共培养体系，通过蛋白质印迹法（Western blot）检测IL-6/JAK/STAT3信号通路的激活状态。后续实验使用敲低IL-6表达的HS-5细胞与托珠单抗干预共培养体系中的AML细胞以靶向该通路，并采用CCK-8法与Annexin V-APC/7-AAD双染法检测AML细胞对阿糖胞苷（Ara-C）的药物敏感性。此外，本研究构建AML异种移植瘤模型开展体内验证实验，评估托珠单抗与阿糖胞苷的协同化疗效应。
实验结果：在黏附型共培养体系中，HS-5细胞分泌的IL-6可激活AML细胞内的STAT3信号通路。无论是敲低IL-6表达还是托珠单抗干预，均可有效抑制JAK2/STAT3的磷酸化水平，从而阻断该通路的激活。一致性实验结果显示，无论在体外还是体内实验环境中，托珠单抗干预均可显著增强AML细胞对阿糖胞苷化疗的敏感性。
结论：托珠单抗通过靶向IL-6/JAK/STAT3信号通路，可增强急性髓系白血病细胞对阿糖胞苷化疗的敏感性。