分泌型PKM2调控肿瘤相关巨噬细胞极化促进结肠癌化疗抵抗的机制研究

Tumor-associated macrophages (TAMs), which promote tumor progression and chemotherapeutic resistance, are critical immunosuppressive cells in the tumor microenvironment. Pyruvate kinase M2 isoform (PKM2) is a key regulatory molecule in tumor aerobic glycolysis. Its abnormal cellular localization is closely related to the malignant tumor progression. Our previous study indicated that the secretion of PKM2 was significantly up-regulated in chemo-resistant colon cancer cells. Secreted PKM2 bound to the surface of macrophage membrane and induced TAMs polarization by regulating tryptophan metabolism. Kynurenine, the tryptophan metabolite, contributes to chemotherapeutic resistance of colon cancer cells. Based on the above findings, this project aims to explore the cell-surface target protein via which secreted PKM2 induced M2 macrophage polarization, clarify the key transcription factor that is implicated in secreted PKM2-induced tryptophan metabolic switch, and finally confirm the effect of TAMs polarization induced by secreted PKM2 on the sensitivity of colon cancer to 5-FU in vivo. In this project, we focus on the communication function of PKM2 in tumor microenvironment, aiming to clarify the new mechanism by which secreted PKM2 induces TAMs polarization thereby promotes colon cancer chemotherapy resistance, and also provide new ideas and theoretical basis for TAMs-targeted cancer therapy.

肿瘤相关巨噬细胞（TAMs）是肿瘤微环境中的重要免疫抑制细胞，它能够促进肿瘤进展和化疗抵抗。M2型丙酮酸激酶（PKM2）是肿瘤有氧糖酵解途径中的关键调控分子，其异常细胞定位与肿瘤恶性进程密切相关。申请人前期研究发现：结肠癌耐药细胞株中PKM2分泌量显著上调；分泌型PKM2结合在巨噬细胞膜表面，通过调控色氨酸代谢诱导TAMs极化，并产生色氨酸代谢产物-犬尿氨酸，导致结肠癌细胞的化疗抵抗。基于以上发现，本项目拟深入发掘分泌型PKM2促进TAMs极化的细胞表面靶蛋白；明确分泌型PKM2调控色氨酸代谢进而促进TAMs极化的关键转录因子；在动物水平证实分泌型PKM2诱导的TAMs极化对结肠癌细胞5-FU敏感性的影响。本项目聚焦于PKM2在肿瘤微环境中的通讯功能，旨在阐明分泌型PKM2诱导TAMs极化促进结肠癌化疗抵抗的新机制，为以TAMs为靶点的结肠癌治疗提供新思路和理论依据。

M2型丙酮酸激酶（PKM2）是肿瘤糖酵解途径的关键调控分子。PKM2异常细胞定位与肿瘤恶性进程密切相关。化疗耐药是限制结肠癌临床治疗的关键。目前，本项目主要围绕PKM2在结肠癌细胞中的异常定位及非典型功能、分泌型PKM2上调IDO1通过释放犬尿氨酸抑制结肠癌细胞衰老并促进化疗耐药以及表面等离子共振技术的建立及抑制结肠癌细胞化疗耐药活性成分的挖掘等三个方面开展工作。主要取得以下成果及关键数据：首先，我们明确了细胞核内PKM2通过活化转录因子FOXO1介导的自噬促进结肠癌细胞化疗耐药；阐明了分泌型PKM2促进肿瘤相关巨噬细胞极化的分子机制；揭示了新型miR-206/hnRNPA1/PKM2信号通路重塑Warburg效应抑制结肠癌生长。其次，阐明分泌型PKM2通过上调肿瘤相关巨噬细胞（TAMs）及肿瘤细胞中的IDO1的表达，促进犬尿氨酸的释放，抑制结肠癌细胞衰老，最终促进结肠癌化疗耐药。最后，我们建立了表面等离子共振技术并依赖该技术挖掘出促进结肠癌细胞化疗敏感性的活性成分：燕麦生物碱AVN A和葫芦素E。以上研究结果为以PKM2、IDO1以及TAMs为靶点的结肠癌治疗提供新策略与新思路。