Tumor ⁃ associated macrophages secrete TGFBI to promote malignancy of glioma stem cells in vitro

Objective To investigate the expression heterogeneity of transforming growth factor⁃β⁃induced protein (TGFBI) in glioblastoma (GBM) multiform and the mechanism of its promotion on malignancy of glioma stem cells (GSCs) in vitro. Methods Using The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA), REMBRANDT and Oncomine database to analyse the potential associations between grades, subtypes, overall survival (OS) of GBM and the expression level of TGFBI and the correlation between TGFBI and tumor⁃associated macrophages (TAMs) marker CD11b and CD163. Treating human monocytes cell line U937 with sequential peripheral blood mononuclear cells and IL⁃4 to get Primed⁃and M2⁃TAMs, quantitative real⁃time polymerase chain reaction (qRT⁃PCR) were used to detect the expression level of markers for M1 ⁃, M2 ⁃ TAMs and TGFBI. Performing immunofluorescent and immunohistochemical stain to reveal the distribution of TGFBI, M2⁃TAMs and GSCs in specimen of GBM patients, adding rhTGFBI to the culture medium to see its impacts on the sphere formation and invasion capacity of NCH⁃421K. Results According to the RNA⁃seq and microarray data of GBM patients in each database, expression level of TGFBI positively correlated to GBM grades and negatively to OS, Futhermore, expression level of TGFBI were strongly correlate with either pan TAMs marker CD11b or M2⁃TAMs marker CD163, and as the induction of U937⁃derived M2⁃TAMs, the expression level of M2⁃TAMs marker and TGFBI increased accompanied by decreasingly M1⁃TAMs marker. Also, we found an obvious co⁃location between TGFBI and CD163, SOX2 in frozen and paraffin sections of GBM specimens. Lastly, we demonstrate that rhTGF86BI could enhance the sphere formation and invasion capacity of NCH⁃421K in vitro. Conclusions M2⁃TAMs secrete TGFBI to promote the sphere formation and invasion capacity of GSCs in GBM. DOI：10.3969/j.issn.1672⁃6731.2019.12.006