脂肪酸受体GPR120介导的癌相关成纤维细胞重编程机制及其对乳腺癌进程影响研究

Tumor microenvironment provides the soil for malignant tumor growth and metastasis, in which cancer-associated fibroblasts (CAF) play an important role. However, the function and regulation mechanism of CAF reprogramming remain unclear. It has been shown that special fatty acid metabolism pressure exists in breast cancer microenvironment. And free fatty acids (FFAs) corresponding to fatty acid receptor GPR120 will influence a variety of cell biology behaviors. Our preliminary experiment showed that four kinds of FFAs including DHA, fatty acid, linoleic acid and eicosapentaenoic acid abnormally elevated in human breast cancer tumor tissues. And normal human Mammary Fibroblast (HMF) can promote the growth of breast cancer once its GPR120 activated. These indicate that FFAs/GPR120 signal is associated with CAF reprogramming, while the exact mechanism still remains unknown. Given the significant role of chemokines in the tumor promoting process of CAF, we also found that activation of GPR120 results a notable evaluated level of chemokine CCL2, CCL5 and epigenetic regulating factor EZH2, but remarkablely decline of metabolic regulation factor PPAR-γ in HMF. Therefore, on the basis of previous work, we further take abnormal fatty acid metabolism and CAF in the breast cancer microenvironment as as the original focus, explore FFA/GPR120 signal induced CAF reprogramming and its effects on breast cancer progress by promoting of tumor inflammatory and metastasis, and clarify associated molecular signaling pathways and key control targets, whereby providing experimental evidence for establishing new tumor therapeutic strategies targeting tumor microenvironment.

肿瘤微环境为恶性肿瘤生长和转移提供土壤，其中癌相关成纤维细胞（CAF）发挥重要作用，但相关重编程作用和调控机制尚不清楚。乳腺癌存在特殊脂肪酸代谢压力，游离脂肪酸（FFAs）作用于相应GPR120受体影响细胞多种生物学行为。我们预初实验发现，人乳腺癌肿瘤组织中4种长链FFAs异常升高，GPR120激活后正常人乳腺成纤维细胞（HMF）促进肿瘤生长，提示FFAs/GPR120信号与CAF重编程相关。鉴于趋化因子在CAF促肿瘤中的作用，我们发现GPR120激活后HMF的CCL2、CCL5分泌和表观调控因子EZH2表达上升，代谢相关调节因子PPAR-γ下降。本项目在前期工作基础上，拟聚焦乳腺癌微环境中脂肪酸代谢异常和CAF，设想研究FFAs/GPR120介导的CAF重编程及其通过促肿瘤炎症反应和转移影响乳腺癌恶性进程的作用，明确关键信号通路和调控靶点；藉此为建立靶向肿瘤微环境的肿瘤治疗新策略提供依据

乳腺癌是世界范围内女性最易罹患的恶性肿瘤，尽管近年来各种治疗方法的出现大大降低了乳腺癌的致死率，但仍有相当数量的乳腺癌患者因肿瘤耐药、复发而死亡，因此亟需新的乳腺癌精准预后评估及个体化治疗方法以改善乳腺癌患者整体疗效。肿瘤微环境在肿瘤发生发展及产生耐药性起极其重要的作用，在乳腺癌细胞所存在的微环境中存在大量的脂肪细胞和脂肪酸，它们通过为肿瘤细胞提供能量、细胞膜性成分、激素及脂质信号分子前体促进肿瘤的进展，但是脂肪酸本身是否作为信号分子参与这一进程目前仍不清楚。本研究首先应用GC-MS技术明确了脂肪酸在乳腺癌患者乳腺组织中的组分变化，发现其中脂肪酸受体的配体脂肪酸含量显著升高；其次我们分离培养乳腺癌癌相关成纤维细胞，发现其高表达GPR120；此外我们在临床样本和肿瘤细胞株发现GPR120的高表达，并通过大样本分析明确脂肪酸/GPR120与乳腺癌患者临床病理特征（耐药、预后和化疗效果）的相关性；进一步的研究发现GPR120的活化可促进癌相关成纤维细胞分泌趋化因子以促进肿瘤转移，同时阐明GPR120通过调控药物泵促进乳腺癌耐药的作用与机制，揭示GPR120活化促进脂肪酸分泌的正反馈调节机制；最后我们探索了靶向干预GPR120对乳腺癌细胞耐药及乳腺癌小鼠的治疗作用。以上发现揭示了肿瘤细胞与肿瘤微环境之间复杂相互作用中的一个未经报道的方面，即GPR120与其内源性脂肪酸配体的相互作用，建立了组织脂质构成与肿瘤生物学行为之间的机制联系，确立了GPR120在乳腺癌生物学中的作用，并显示了其作为乳腺癌治疗策略新靶标的潜能。