Fig. 7
High TSPO expression marks mesenchymal glioblastoma cell subpopulations characterized by elevated numbers of tumor-associated macrophages. Principal component analysis of RNA-Seq data showed a separation of a cluster (TSPO HIGH III) consisting of all mesenchymal GBMs from the non-mesenchymal GBMs (TSPO LOW I, TSPO HIGH II) (a). ssGSEA with gene sets defining cellular states in GBM [52] revealed an enrichment of the MES1/2-like cellular states in the HIGH III cluster of the TSPO-high group (b). Gene expression of MES-like TAM tumor cell interaction genes [30] is upregulated in the TSPO HIGH III compared to the TSPO LOW I cluster (c). Deconvolution of bulk sequencing data shows a significant larger TAM cell proportion in TSPO HIGH III cluster in comparison to TSPO HIGH II and TSPO LOW I (d). Representative images of OPAL multiplex immune fluorescence staining showed a higher TSPO/CD68-positive cell portion in the TSPO HIGH III (GBM_25) case in comparison to TSPO HIGH II (GBM_11 II) and TSPO LOW I (GBM_17) cases (e), whole OPAL images and corresponding H&E staining can be found in Suppl. Figure 7. Quantifications (%positive cells) of TSPO-positive and TSPO/CD68-positive cell portion by counting of n = 2 TSPO LOW I, n = 1 TSPO HIGH II and n = 2 TSPO HIGH III cases verified those findings (f). Significances are displayed as follows: p > 0.05 = n.s., p < 0.05 = *, p < 0.01 = **, p < 0.001 = ***. AC: astrocyte like, CD44: cluster of differentiation 44, CD68: cluster of differentiation 68/ macrosialin, DAPI: 4′,6-diamidino-2-phenylindole, GBM: glioblastoma, IL6ST: GP130/ glycoprotein 130, LIFR: leukemia inhibitory factor receptor, MES1/3: mesenchymal-like, NES: normalized enrichment score, NPC1/2: neural progenitor like, ODC: oligodendrocytic cells, OPC: oligodendrocyte progenitor like, OSM: oncostatin M, OSMR: oncostatin M receptor, PC1/2: principal component dimension 1 and 2, STAT3: signal transducer and activator of transcription 3, ssGSEA: single sample gene set enrichment analysis, TAM: tumor-associated macrophages