Glioma Cells in the Tumor Periphery Have a Stem Cell Phenotype

Abstract

Gliomas are highly infiltrative tumors incurable with surgery. Although surgery removes the bulk tumor, tumor cells in the periphery are left behind resulting in tumor relapses. The aim of the present study was to characterize the phenotype of tumor cells in the periphery focusing on tumor stemness, proliferation and chemo-resistance. This was investigated in situ in patient glioma tissue as well as in orthotopic glioblastoma xenografts. We identified 26 gliomas having the R132 mutation in Isocitrate DeHydrogenase 1 (mIDH1). A double immunofluorescence approach identifying mIDH1 positive tumor cells and a panel of markers was used. The panel comprised of six stem cell-related markers (CD133, Musashi-1, Bmi-1, Sox-2, Nestin and Glut-3), a proliferation marker (Ki-67) as well as a chemo-resistance marker (MGMT). Computer-based automated classifiers were designed to measure the mIDH1 positive nucleus area-fraction of the chosen markers. Moreover, orthotopic glioblastoma xenografts from five different patient-derived spheroid cultures were obtained and the tumor cells identified by human specific immunohistochemical markers. The results showed that tumor cells in the periphery of patient gliomas expressed stem cell markers, however for most markers at a significantly lower level than in the tumor core. The Ki-67 level was slightly reduced in the periphery, whereas the MGMT level was similar. In orthotopic glioblastoma xenografts all markers showed similar levels in the core and periphery. In conclusion tumor cells in the periphery of patient gliomas have a stem cell phenotype, although it is less pronounced than in the tumor core. Novel therapies aiming at preventing recurrence should therefore take tumor stemness into account. Migrating cells in orthotopic glioblastoma xenografts preserve expression and stem cell markers. The orthotopic model therefore has a promising translational potential.

Overcoming therapeutic resistance in glioblastoma: the way forward

“…Thus, we lack a sample of the tumor cells from the location of the recurrent tumor, and just have cells from the resected tumor bulk. This is important, as the biological features of deeply infiltrated cells may be different from those from the resected primary tumor (134,135). To overcome this limitation, mouse models have been used to garner data on the molecular changes associated with radio-(55) and chemotherapies (20).…”

Spontaneous Glioblastoma Spheroid Infiltration of Early-Stage Cerebral Organoids Models Brain Tumor Invasion

“…[3][4][5] Emerging experimental and histological evidence indicates that GBM cell migration is accompanied by the expression of stem cell markers and can be predictive of patient outcomes. [6][7][8] Therefore, interventions that specifically target the invasive GBM phenotype are highly desirable. However, the molecular mechanisms underlying the infiltrative nature of GBM cells are not well understood.…”

A tumorsphere model of glioblastoma multiforme with intratumoral heterogeneity for quantitative analysis of cellular migration and drug response

“…Only subtle progress in patient prognosis has been made during the past two decades with a two-month increase in median survival by the addition of temozolomide to the treatment regimen [25]. The cells that most frequently invade the surrounding brain parenchyma and migrate far away from the tumor core (or primary tumor) have been shown to possess stem-like properties [26][27][28]. Understanding the invading and migrating GBM cells potentially harbors an avenue for improving treatment and therefore patient prognosis.…”