PRL-3通过外泌体αvβ5促进结肠癌肝脏转移前微环境形成的作用及机制

PRL-3 is an Oncoprotein Associated with Liver Metastasis of Colon Cancer，metastasis depends on the formation of primary and target organ microenvironment. Our previous study confirmed PRL-3 regulation of colon cancer primary micro-environment, and enhance tumor cell invasiveness. However, whether PRL-3 regulates the pre-hepatic metastasis of colon cancer is unclear. Researches confirmed that integrin αvβ5 is a membrane protein associated with tumor-specific liver metastasis. Pre-experiments showed that: 1) PRL-3 upregulated integrin αvβ5 in exosomes of colon cancer; 2) uptake of αvβ5 in exosomes by Kupffer cells , and induce myeloid suppress cells(MDSCs) infiltration in liver. MDSCs have the role of regulation of tumor cells microenvironment. Therefore, we propose a scientific hypothesis: PRL-3 through the exosome αvβ5 affect the liver pre-metastasis microenvironment and promote colon cancer liver metastasis. This study intends to investigate in depth the mechanisms by which PRL-3 up-regulates exosome αvβ5 expression and the recruitment of exosomes by Kupffer cells to induce the recruitment of MDSCs to the liver to form a pre-metastatic microenvironment. Our Study is to provide a new theoretical basis in PRL-3 promote liver metastases of colon cancer .

PRL-3是与结肠癌肝转移相关的癌蛋白,肿瘤远处转移依赖原发灶和靶器官微环境的形成。我们前期证实:PRL-3调控结肠癌原发灶微环境,促进肿瘤细胞侵袭,但其能否调控转移靶器官-肝脏的微环境尚不清楚。研究证实整合素αvβ5是肿瘤特异性肝转移相关的膜蛋白,我们预实验发现:1)PRL-3可上调结肠癌细胞外泌体中整合素αvβ5含量;2)肝脏Kupffer细胞摄取外泌体中αvβ5,并诱导髓源性抑制细胞(MDSCs)浸润。而MDSCs是一种参与调控转移前微环境形成的细胞。由此我们提出科学假设:PRL-3通过外泌体中αvβ5,诱导肝脏MDSCs浸润,调控肝转移前肝脏微环境,促进结肠癌肝转移。本研究拟探讨PRL-3上调外泌体中αvβ5表达的机制,以及Kupffer细胞摄取外泌体后诱导MDSCs肝脏募集,形成转移前微环境的作用和机制,为完善PRL-3促进结肠癌肝转移提供新的理论依。

PRL-3表达与结肠癌肝转移相关,前期证实PRL-3调控结肠癌原发灶微环境,促进肿瘤细胞侵袭和肝转移。肿瘤远处转移依赖靶器官转移前微环境（PMNs）的形成，外泌体在PMNs调控中发挥主要调控作用，PRL-3是否参与调控PMNs尚不清楚。研究中，我们通过构建C67BL/6小鼠结肠癌肝转移模型，发现PRL-3参与诱导MDSC在肝脏中浸润，调控PMNs形成，促进结肠癌细胞肝转移；进一步的外泌体蛋白组学结果提示高表达PRL-3的结肠癌患者外周血中富含外泌体ITGαvβ5，两者在结肠癌组织中表达正相关，并且与肝转移相关。高表达的患者OS和PFS更短，预后差。在体外细胞实验中进一步证实PRL-3通过MYOF调控Rab35/27A通路，从而调控结肠癌细胞分泌外泌体ITGαvβ5；随后，通过小鼠体内外泌体预教育发现，肝脏中Kupffer细胞摄取外泌体ITGαvβ5，诱导MDSC的浸润，抑制CD8+T细胞，调控PMNs形成，促进结肠癌肝转移。最后我们在体外细胞和小鼠体内证实外泌体ITGαvβ5通过p38/STAT1通路调控Kupffer细胞分泌趋化因子CXCL12，从而诱导MDSC浸润，促进肝PMNs形成和结肠癌肝转移。我们的研究结果表明PRL-3通过外泌体ITGαvβ5调控Kupffer细胞分泌CXCL12诱导MDSC在肝脏中浸润，形成肝PMNs，从而促进结肠癌肝转移，或许成为结肠癌新的预后标记物.