miR-146b-5p下调促进巨噬细胞与胶质瘤干细胞融合后恶性转化的分析

Down-regulation of miR-146b-5p promotes malignant transformation of fusion cells after co-culture of macrophages with glioma stem cells in vitro

目的观察在巨噬细胞（Mφ）-胶质瘤干细胞（GSCs）双色荧光示踪体外共培养模型中，二者间的相互作用，以多指标验证融合细胞的存在及其生物学特性，并分析相关分子机制。方法将红色荧光蛋白基因稳定转染的人GSCs细胞株SU4-RFP，与源于绿色荧光蛋白（EGFP）Balb／c裸小鼠的Mφ体外共培养，细胞工作站下观察SU4-RFP与Mφ间的包括融合在内的多种相互作用，克隆高增殖力RFP／EGFP双阳性细胞，以免疫印迹、荧光探针原位杂交（FISH）、免疫细胞化学染色和染色体核型分析多指标鉴定融合细胞，命名为Mφ与GSCs的融合细胞（F—Mφ），分析其生物学特性及相关分子机制。结果体外共培养发现高增殖力EGFP／RFP双阳性细胞存在，单克隆并连续传代后在转录、翻译及荧光蛋白表达水平均证实RFP和EGFP共表达。融合细胞共表达Mφ标志物CD68和GSCs标志物Nestin，兼具两种细胞特征性染色体，证实其源于SU4-RFP与Mφ的自发融合。融合细胞的增殖速度、侵袭能力均高于SU4-RFP。融合细胞转染miR-146b-5p后，STAT3表达下降，凋亡率上升（18．83％），而致瘤率（4／5）及肿瘤体积（9．7mm±1．6mm）均下降。结论Mφ可与GSCs自发融合，融合细胞转化后恶性程度更高，与miR-146b-5p下调介导STAT3通路激活相关。

Objective To observe mutual interactions between macrophages（Mφ） and glioma stem cells （GSCs）in dual-color tracing model in vitro, to identify the biological characteristics of fusion cells in multiple levels, and to analysis the relevant molecular mechanisms. Methods Red fluorescent protein （RFP） gene was stably transfeeted into human GSCs cell line SU4. Mφ cells were obtained from Balb/c nude mice with enhanced green fluorescent protein （EGFP） expression. Then two cells were co-cultured in dual-color tracing platform. RFP/EGFP double positive cells with high proliferation ability were monocloned. The fusion cells were verified by Western blot, fluorescence in situ hybridization, immunocytochemistry and chromosome karyotype analysis. The biological characteristics of fusion ceils were further analyzed, together with relevant molecular changes. Results RFP / EGFP double positive cells were obtained through in vitro co-culture. RFP and EGFP coexpression were proved at transcriptional and translational levels in the fusion ceils. They also co-expressed GSCs marker Nestin and Mφ marker CD68, and karyotype analysis showed two types of characteristic chromosomes, which confirmed that the fusion cells originated from spontaneous fusion between SU4-RFP and Mφ. Fusion cell proliferation rate and invasion ability were higher than SU4-RFP, which were relevant with down-regulation of miR-146b-5p and activation of STAT3. Fusion cells transfected with miR-146b-5p showed a higher apoptosis rate（ 18.83% ） and lower tumor formation （4/5）. Conclusion Mφ could fuse with GSCs spontaneously in local tumor micro- environment. The proliferation and invasion abilities of fusion cells were higher than their parent cells, which were relevant with down-regulation of miR-146b-5p and activation of STAT3. It revealed the possible mechanisms of malignant progression of gliomas.