Triple-negative breast cancer (TNBC), defined as loss of estrogen, progesterone, and Her2 receptors, is a subtype of highly aggressive breast cancer with worse prognosis and poor survival rate. Macrophage migration inhibitory factor (MIF) is a pleiotropic pro-inflammatory cytokine aberrantly expressed in many solid tumors and known to promote tumor progression and metastasis. However, its role in TNBC progression and metastasis is unexplored. Here we have shown that in TNBC patients, MIF expression was significantly enriched in the tumor compared to adjacent normal tissue. Using publically available patient datasets, we showed that MIF overexpression correlates with worse survival in TNBC compared to other hormonal status. Orthotopic implantation of TNBC cells into MIF knockout mice showed reduced tumor growth compared to wild-type mice. In addition, we have shown that MIF downregulation inhibits TNBC growth and progression in a syngeneic mouse model. We further showed that CPSI-1306, a small-molecule MIF inhibitor, inhibits the growth of TNBC cells in vitro. Mechanistic studies revealed that CPSI-1306 induces intrinsic apoptosis by alteration in mitochondrial membrane potential, cytochrome c (Cyt c) release, and activation of different caspases. In addition, CPSI-1306 inhibits the activation of cell survival and proliferation-related molecules. CPSI-1306 treatment also reduced the tumor growth and metastasis in orthotopic mouse models of mammary carcinoma. CPSI-1306 treatment of tumor-bearing mice significantly inhibited TNBC growth and pulmonary metastasis in a dose-dependent manner. Histological analysis of xenograft tumors revealed a higher number of apoptotic cells in CPSI-1306-treated tumors compared to vehicle controls. Our studies, for the first time, show that MIF overexpression in TNBC enhances growth and metastasis. Taken together, our results indicate that using small molecular weight MIF inhibitors could be a promising strategy to inhibit TNBC progression and metastasis.

三阴性乳腺癌 (TNBC)，定义为雌激素、孕激素和 Her2 受体的丧失，是一种预后较差且存活率较差的高侵袭性乳腺癌亚型。巨噬细胞迁移抑制因子 (MIF) 是一种多效性促炎细胞因子，在许多实体瘤中异常表达，已知可促进肿瘤进展和转移。然而，其在 TNBC 进展和转移中的作用尚未探索。在这里我们已经表明，在 TNBC 患者中，与邻近的正常组织相比，MIF 表达在肿瘤中显着富集。使用公开可用的患者数据集，我们表明与其他激素状态相比，MIF 过度表达与 TNBC 中较差的存活率相关。与野生型小鼠相比，将 TNBC 细胞原位植入 MIF 敲除小鼠显示肿瘤生长减少。此外，我们已经证明 MIF 下调抑制了同基因小鼠模型中 TNBC 的生长和进展。我们进一步表明，小分子 MIF 抑制剂 CPSI-1306 在体外抑制 TNBC 细胞的生长。机制研究表明，CPSI-1306 通过改变线粒体膜电位、细胞色素来诱导内在细胞凋亡c (Cyt c ) 释放，并激活不同的半胱天冬酶。此外，CPSI-1306 抑制细胞存活和增殖相关分子的激活。CPSI-1306 治疗还减少了乳腺癌原位小鼠模型中的肿瘤生长和转移。CPSI-1306 对荷瘤小鼠的治疗以剂量依赖性方式显着抑制 TNBC 生长和肺转移。异种移植肿瘤的组织学分析显示，与载体对照相比，CPSI-1306 治疗的肿瘤中有更多数量的凋亡细胞。我们的研究首次表明，TNBC 中的 MIF 过表达促进了生长和转移。总之，我们的结果表明，使用小分子量 MIF 抑制剂可能是抑制 TNBC 进展和转移的有前途的策略。