线粒体CD147/MCT1/LDHB乳酸氧化复合物促进失巢乳腺癌细胞重编程

Our previous studies indicated that detachment induces breast cancer cells to reprogram into metastasis-initiating cells. To eradicate the metastasis-initiating cells, it is essential to explore the detachment induced reprogramming mechanism in breast cancer cells. Recent literatures showed that circulating lactate is utilized as the main fuel and oxidized for tumor growth and metastasis. Besides, lactate promotes the function of cancer stem cells. These findings raise the possibility that lactate may mediate the reprogramming of breast cancer cells. However, the mechanism of lactate oxidation remains unclear. ..We recently found that CD147 regulates the ratio and function of breast cancer stem cells, and promotes the detachment induced reprogramming in breast cancer cells. CD147 is localized in mitochondria and co-localized with lactate transport and oxidation protein MCT1 and LDHB. CD147 correlates with lactate uptake and promotes the oxidative phosphorylation in detached breast cancer cells. All these data suggest that CD147 may involve in regulating lactate oxidation. ..In this project, we propose to construct CTC derived PDX models as well as in vitro and in vivo cell or mouse model for CD147 over-expression in mitochondria. We would explore the new mechanism that mitochondrial CD147 promotes the detachment induced reprogramming in breast cancer cells by mediating the formation of lactate oxidation complex with MCT1 and LDHB, enhancing the lactate uptake and oxidation, and then promoting the oxidative phosphorylation metabolic pathway. The completion of this project would contribute to the development of a novel therapeutic target and strategy for successful prevention and treatment of tumor metastasis.

申请者前期研究表明，失巢应激诱导了乳腺癌细胞重编程为转移性起始细胞。因此，探讨失巢乳腺癌细胞的重编程机制，对于靶向根除转移性起始细胞至关重要。新近文献证明，循环乳酸可作为主要燃料被氧化并促进肿瘤生长转移，乳酸又可促进肿瘤干细胞功能，因而可能介导了失巢乳腺癌细胞重编程，但乳酸氧化的机制尚不清楚。我们近期预实验发现，CD147可调节乳腺癌干细胞比例及功能，并促进失巢诱导的乳腺癌细胞重编程；CD147定位于线粒体并与乳酸摄取氧化蛋白MCT1、LDHB共定位，与失巢乳腺癌细胞摄取乳酸相关，并促进氧化磷酸化，提示CD147可能调控了乳酸氧化过程。本项目拟利用CTC来源PDX模型，建立线粒体特异性CD147表达的体内外模型，研究线粒体CD147通过与MCT1、LDHB形成乳酸氧化复合物，促进乳酸摄取氧化，介导氧化磷酸化代谢途径，导致失巢乳腺癌细胞重编程的新机制，进而为肿瘤转移防治提供新策略和新靶点。

如何靶向根除转移性起始细胞（MICs），是当前肿瘤转移机制研究及抗肿瘤转移治疗的热点难点。项目前期研究表明，失巢应激诱导了乳腺癌细胞重编程为MICs。因此，探讨失巢乳腺癌细胞的重编程机制，对于靶向根除MICs至关重要。.本项目旨在从代谢重塑角度揭示失巢乳腺癌重编程分子机制，观察失巢乳腺癌细胞摄取氧化乳酸进而重编程为MICs的生物学现象；探讨mito-CD147对失巢乳腺癌细胞乳酸摄取氧化的影响；分析mito-CD147通过MCT1/LDHB促进失巢乳腺癌细胞乳酸摄取氧化的机制；最后，初步探索CD147定位于线粒体的分子机制。.总体上，本项目深入阐明了mito-CD147与MCT1/ LDHB形成线粒体乳酸氧化复合物，促进乳酸摄取氧化，导致失巢乳腺癌细胞重编程及转移的全新机制；回答了失巢乳腺癌细胞如何获能并转移的关键科学问题，即MICs起源的失巢重编程机制问题；研究成果为开发有效的乳腺癌转移防治新策略提供新靶点，为拓展CD147抗体药物的治疗应用提供新线索。.取得重要进展有：1）发现了失巢条件下乳腺癌细胞摄取氧化乳酸，借助线粒体氧化磷酸化（OXPHOS）获能并重编程为MICs，进而促进肿瘤转移的重要细胞病理现象。2）揭示了失巢乳腺癌细胞发生肿瘤转移的具体机制，即mito-CD147促进失巢乳腺癌细胞mito-CD147/MCT1/LDHB乳酸氧化复合物形成，介导乳酸摄取氧化，进而重编程为MICs的重要细胞生物学现象。3）深入阐明了失巢乳腺癌细胞乳酸氧化复合物介导OXPHOS获能并重编程为MICs的表观遗传学机制，即：乳酸摄取氧化后进入OXPHOS，其主要代谢产物a-KG水平增加，进而抑制DNMT3B活性，降低干性基因SOX2启动子区DNA甲基化。4）初步探讨了CD147定位线粒体的分子机制，即线粒体分子伴侣DNAJC19/ HSP60介导CD147定位线粒体并促进其干性维持作用。.