Flotillin‐1 is a prognostic biomarker for glioblastoma and promotes cancer development through enhancing invasion and altering tumour microenvironment

FIGURE 1. Expression level of FLOT1 in GBM and its subtypes. (A) Differential expression of FLOT1 between GBM and normal brain tissue. (B) IHC staining of FLOT1 in GBM and normal brain tissue. (C) FLOT1 expression in IDH1 wildtype and IDH1 mutant samples based on TCGA and CGGA database. (D) The expression of FLOT1 in MGMT‐methylated and MGMT‐unmethylated samples based on TCGA and CGGA database. (E) The expression of FLOT1 in different GBM subtypes based on TCGA and CGGA datasets.

FIGURE 2. FLOT1 could be a prognostic factor for GBM patients. (A) Kaplan–Meier survival analysis shows higher FLOT1 expression predicts a poorer prognosis for GBM patients based on the TCGA database. (B) Kaplan–Meier survival analysis shows higher FLOT1 expression predicts a poorer prognosis for GBM patients based on the CGGA database.

FIGURE 3. FLOT1 is associated with GBM proliferation, migration, invasion and p‐ERK level in vitro. (A) Western blot shows the FLOT1 expression level in FLOT1 overexpressed U87 cells and FLOT1 knockdown U251 cells. (B) MTT assay reveals the proliferation ability of GBM cells, which overexpressed FLOT1 or knocked down FLOT1. (C) The wound healing assay demonstrates the migration ability of GBM cells, which overexpressed FLOT1 or knocked down FLOT1. (D) Transwell assay shows the invasive ability of GBM cells in which FLOT1 was overexpressed or knocked down. (E, F) The relationship between FLOT1 and MAPK signalling according to the TCGA and CGGA database. (G) Western blot shows the p‐ERK level difference between control and FLOT1 overexpressed U87 cells. All in vitro experiments were performed in triplicate and at least three times.

FIGURE 4. FLOT1 promotes GBM tumour growth in xenograft mouse model. (A) Picture of tumours from FLOT1‐OE and control group 42 days after cells were inoculated. (B) Tumours were weighed. (C) Tumour sizes were monitored every 6 days.

FIGURE 5. Functional enrichment analysis of FLOT1 in GBM patients (A) Top eight biological process (BP) terms in GO enrichment based on TCGA database. (B) Top eight cellular component (CC) terms of FLOT1 in the TCGA database. (C) Top eight molecular function (MF) terms of GO enrichment based on TCGA database. (D) KEGG pathways were analysed based on TCGA datasets, and the top 8 terms were listed.

FIGURE 6. Positive correlation between the FLOT1 expression and the immune score in GBM patients. (A) The correlation between the expression of FLOT1 and ImmuneScore, StromalScore and ESTIMATEScore basing on the TCGA database. (B) The correlation between FLOT1 expression and ImmuneScore, StromalScore and ESTIMATEScore basing on the CGGA database.

FIGURE 7. Immune infiltration of the high‐FLOT1 and the low‐FLOT1 groups. (A, B) Box plot shows comparison of immune cell fractions based on TCGA or CGGA datasets. (C, D) Heat map shows the correlation of 28 immune cell fractions based on TCGA or CGGA datasets.