Glioma Initiating Cells Form a Differentiation Niche Via the Induction of Extracellular Matrices and Integrin αV

<div><p>Glioma initiating cells (GICs) are considered responsible for the therapeutic resistance and recurrence of malignant glioma. To clarify the molecular mechanism of GIC maintenance/differentiation, we established GIC clones having the potential to differentiate into malignant gliomas, and subjected to DNA microarray/iTRAQ based integrated proteomics. 21,857 mRNAs and 8,471 proteins were identified and integrated into a gene/protein expression analysis chart. Gene Ontology analysis revealed that the expression of cell adhesion molecules, including integrin subfamilies, such as <u>α</u>2 and <u>α</u>V, and extracellular matrices (ECMs), such as collagen IV (COL4), laminin <u>α</u>2 (LAMA2), and fibronectin 1 (FN), was significantly upregulated during serum-induced GIC differentiation. This differentiation process, accompanied by the upregulatio<u>n</u> of MAPK as well as glioma specific proteins in GICs, was dramatically accelerated in these ECM (especially FN)-coated dishes. Integrin <u>α</u>V blocking antibody and RGD peptide significantly suppressed early events in GIC differentiation, suggesting that the coupling of ECMs to integrin <u>α</u>V is necessary for GIC differentiation. In addition, the expression of integrin <u>α</u>V and its strong ligand FN was prominently increased in glioblastomas developed from mouse intracranial GIC xenografts. Interestingly, during the initial phase of GIC differentiation, the RGD treatment significantly inhibited GIC proliferation and raised their sensitivity against anti-cancer drug temozolomide (TMZ). We also found that combination treatments of TMZ and RGD inhibit glioma progression and lead the longer survival of mouse intracranial GIC xenograft model. These results indicate that GICs induce/secrete ECMs to develop microenvironments with serum factors, namely differentiation niches that further stimulate GIC differentiation and proliferation via the integrin recognition motif RGD. A combination of RGD treatment with TMZ could have the higher inhibitory potential against the glioma recurrence that may be regulated by the GICs in the differentiation niche. This study provides a new perspective for developing therapeutic strategies against the early onset of GIC-associated glioma.</p></div

Additional file 2: Table S1. of A combination of TERT promoter mutation and MGMT methylation status predicts clinically relevant subgroups of newly diagnosed glioblastomas

Molecular and clinical characteristics of Cohort 1 (n = 758). Table S2. Molecular and clinical characteristics of GBM cohort (n = 453). Table S3. Univariate and multivariate Cox regression analyses for Group A (IDH mutated-TERT mutated) tumors in Cohort 1 (n = 155). Table S4. Univariate and multivariate Cox regression analyses for Group B (IDH mutated-TERT wild-type) tumors in Cohort 1 (n = 131). Table S5. Univariate and multivariate Cox regression analyses for Group C (IDH wild-type-TERT wild-type) tumors in Cohort 1 (n = 237). Table S6. Univariate and multivariate Cox regression analyses for Group D (IDH wild-type-TERT mutated) tumors in Cohort 1 (n = 235). Table S7. Univariate and multivariate Cox regression analyses for GBM in Cohort 1 (n = 260). Table S8. Univariate and multivariate Cox regression analyses for GBM in Cohort 2 (n = 193). Table S9. Background of combined GBM cohort stratified by TERT and MGMT status (n = 453). Table S10. Survival time and WHO grade in each molecular subgroup of Cohort 1 (n = 758). (XLSX 254 kb

Additional file 3: Figure S1. of A combination of TERT promoter mutation and MGMT methylation status predicts clinically relevant subgroups of newly diagnosed glioblastomas

Distributions of molecular alterations according to histology in Cohort 1. Figure S2. Kaplan-Meier analysis for Group A cases stratified by 1p/19q status. Figure S3. Kaplan-Meier analyses for GBM cases in Cohorts 1 and 2. (PPTX 172 kb

Additional file 1: of A combination of TERT promoter mutation and MGMT methylation status predicts clinically relevant subgroups of newly diagnosed glioblastomas

Supplementary Information. (DOCX 141 kb