磷脂酰丝氨酸调控肿瘤微环境内巨噬细胞M2型极化的分子机制研究

Macrophages in the tumor microenvironment are generally subscribed to alternatively activated M2 protumorigenic macrophages, which could promote tumor growth, progression, and metastasis through the secretion of immune-suppressive factors etc. Meanwhile, apoptotic cells are most commonly co-localized with macrophages in tumors, and the phagocytic response is accompanied by the polarization of M2 phenotype in macropahegs, however, the molecular mechanisms under the polarization is still unclear. In the present study, we have discovered that Phosphatidylserine (PS) isolated from the apoptotic tumor cells could significantly induce M2 macrophage polarization both in vitro and in vivo, and interestingly, this is accompanied by the up-regulation of JMJD3 (a histone demethylase in epigenetic regulation) gene level. However, the molecular pathways concerned with JMJD3 up-regulation and macrophage M2 polarization induced by phosphatidylserine (PS) remains to be explored. Therefore, in the current study, we will make investigations on the related receptors, signaling pathways which might be involved in the macrophage M2 polarization induced by phosphatidylserine (PS), in the meantime, seeking the new potential target by performing protein/ gene microarray analysis. Furthermore, critical pathways involved in the induction of macrophage M2 polarization by phosphatidylserine (PS) might be interfered in vivo with specific inhibitors, antibodies or by the utilization of gene knockout mice to investigate how they affect the tumor growth and tumor microenvironment. This study may explore new therapeutic targets and more possibilities for tumor therapy. The applicant has the experience of publishing papers in the Journal such as Cell Res, also, the innovative work we have done so far might contribute to the accomplishment of this study.

肿瘤微环境内的巨噬细胞多为M2型，通过分泌免疫抑制因子等途径促进肿瘤生长，并且巨噬细胞常与凋亡的肿瘤细胞呈共定位（Co-localized）。巨噬细胞吞噬凋亡的肿瘤细胞后可诱导M2型极化，但分子机制尚不清楚。我们前期未发表的工作从凋亡肿瘤细胞已鉴定出了磷脂酰丝氨酸，发现其能诱导巨噬细胞M2型极化，并有组蛋白去甲基化酶JMJD3上调，而磷脂酰丝氨酸是否及如何诱导JMJD3上调，并参与M2型极化也尚未见报道。本研究将对磷脂酰丝氨酸促进M2型极化依赖的受体、JMJD3上下游通路及可能的其它新通路进行研究，并将在小鼠肿瘤模型中，用小分子、抗体、基因敲除小鼠等干预磷脂酰丝氨酸诱导M2型极化的相关通路，观察对肿瘤生长及其微环境的影响，为M2型极化的机制与肿瘤干预治疗提供新思路。负责人有在Cell Res.等发表论文的经历，且本课题已有充分的前期工作基础，有助于课题顺利实施。

肿瘤的发生发展和预后都与肿瘤微环境密切相关，本课题旨在讨论肿瘤微环境中免疫抑制细胞，肿瘤相关巨噬细胞的来源及在其中的作用。肿瘤相关巨噬细胞大多具有M2型巨噬细胞的表型，能通过分泌免疫抑制因子等多种途径促进肿瘤生长，本课题的研究计划分为两大部分，包括：（1）磷脂酰丝氨酸（PS）诱导巨噬细胞M2 型极化相关分子机理的研究；（2）在小鼠肿瘤模型中研究试验筛选出的相关通路对肿瘤生长及其微环境的影响。本课题圆满完成了所有研究目标。我们从凋亡细胞中鉴定出了能诱导巨噬细胞M2型极化的单个生物分子——磷脂酰丝氨酸（PS），首先证明了来自凋亡细胞的凋亡肿瘤细胞和磷脂酰丝氨酸均可将巨噬细胞转变为M2样表型，发现PS能在体外诱导巨噬细胞M2样的表型极化，并且阐明了来自凋亡肿瘤细胞的磷脂酰丝氨酸是通过PSRs-Stat3-Jmjd3通路在巨噬细胞中诱导M2样表型的。进一步，在M2型极化的研究方面，我们研究了PS相关受体在诱导巨噬细胞M2极化中的作用，通过几种小分子抑制剂进行了证实。在第二部分中，我们不仅在动物体内实验中证明了PS能在体内诱导M2样巨噬细胞并促进肿瘤生长，并且在小鼠肿瘤模型中，用筛选出的相关通路抑制剂对肿瘤生长及其微环境的作用进行了研究，有效阻断肿瘤微环境中M2 型巨噬细胞的转化，减少M2 型巨噬细胞的比例，改变微环境构成，从而抑制肿瘤的生长，延长小鼠生存期，为干预肿瘤微环境的肿瘤治疗研究提供新思路。