Augment proteasome inhibitor efficacy activates CD8+ T cell-mediated antitumor immunity in breast cancer

Although three proteasome inhibitors have been used for liquid tumor treatment, their effectiveness against solid tumors remains inadequate. To address this issue, we employed a drug combination strategy and discovered that ammonium tetrathiomolybdate (TM) and AMD3100 can sensitize solid cancer cell lines to proteasome inhibitors. Mechanistically, we found that TM and AMD3100 reduce proteasome activity by decreasing the protein level of PSMB5. This reduction occurs through the activation of the AMPK pathway, which inhibits STAT3 phosphorylation. Notably, our in vivo studies revealed that drug combinations retarded tumor growth dependent on CD8+ T cells. The combination of bortezomib with TM or AMD3100 induced cancer cell antigen presentation and the production of CCL5, which together stimulated the recruitment and generation of cytotoxic CD8+ T cells. This study identifies new synergistic lethal pairs that enhance the effectiveness of bortezomib-centered therapy against breast cancer. HCC1937 cells treated with vehicle, 10μM TM or 10μM AMD3100 were collected for RNA-Seq. MDA-MB-231 cells treated with 10nM Bortezomib combined with 10μM TM or 10μM AMD3100 were collected for RNA-Seq. 4T1 tumor implanted into Balb/c mice were treated with 1mg/kg bortezomib every 4 days combined with 0.05mg/ml TM in drinking water or 5mg/kg AMD3100 every 2 days and collected for RNA-Seq.

尽管已有三种蛋白酶体抑制剂（proteasome inhibitors）被应用于血液肿瘤的治疗，但其对实体瘤的疗效仍不尽如人意。为解决这一临床难题，本研究采用药物联合策略，发现四硫钼酸铵（ammonium tetrathiomolybdate，TM）与AMD3100可使实体癌细胞系对蛋白酶体抑制剂产生增敏效应。机制层面的研究显示，TM与AMD3100可通过降低PSMB5的蛋白水平以抑制蛋白酶体活性，该调控过程依赖于腺苷酸活化蛋白激酶（AMPK）通路的激活，而该通路可进一步抑制信号转导与转录激活因子3（STAT3）的磷酸化。值得关注的是，体内实验结果表明，该药物联合疗法可通过CD8阳性T细胞（CD8+ T cells）依赖性机制延缓肿瘤生长。硼替佐米（bortezomib）分别与TM或AMD3100联合给药时，可诱导癌细胞的抗原呈递过程及CCL5的产生，二者协同刺激细胞毒性CD8阳性T细胞的招募与生成。本研究鉴定出全新的协同致死药物组合，可显著增强以硼替佐米为核心的乳腺癌治疗方案的疗效。实验样本收集方案如下：①将经溶剂对照、10μM TM或10μM AMD3100处理的HCC1937细胞收集后进行转录组测序（RNA-Seq）；②将经10nM硼替佐米联合10μM TM或10μM AMD3100处理的MDA-MB-231细胞收集后进行转录组测序；③对接种于BALB/c小鼠体内的4T1肿瘤进行给药干预：每4天给予1mg/kg硼替佐米，同时通过饮水提供0.05mg/ml TM，或每2天给予5mg/kg AMD3100，随后收集样本进行转录组测序。