Characterization of G-CSF receptor expression in medulloblastoma

Abstract

Background Identifying mechanisms of medulloblastoma recurrence is a key to improving patient survival, and targeting treatment-resistant subpopulations within tumors could reduce disease recurrence. Expression of the granulocyte colony-stimulating factor receptor (G-CSF-R, CD114) is a potential marker of cancer stem cells, and therefore we hypothesized that a subpopulation of medulloblastoma cells would also express CD114 and would demonstrate chemoresistance and responsiveness to G-CSF. Methods Prevalence of CD114-positive (CD114+) cells in medulloblastoma cell lines, patient-derived xenograft (PDX) tumors, and primary patient tumor samples were assessed by flow cytometry. Growth rates, chemoresistance, and responses to G-CSF of CD114+ and CD114-negative (CD114−) cells were characterized in vitro using continuous live cell imaging and flow cytometry. Gene expression profiles were compared between CD114+ and CD114− medulloblastoma cells using quantitative RT-PCR. Results CD114+ cells were identifiable in medulloblastoma cell lines, PDX tumors, and primary patient tumors and have slower growth rates than CD114− or mixed populations. G-CSF accelerates the growth of CD114+ cells, and CD114+ cells are more chemoresistant. The CD114+ population is enriched when G-CSF treatment follows chemotherapy. The CD114+ population also has higher expression of the CSF3R, NRP-1, TWIST1, and MYCN genes. Conclusions Our data demonstrate that a subpopulation of CD114+ medulloblastoma cells exists in cell lines and tumors, which may evade traditional chemotherapy and respond to exogenous G-CSF. These properties invite further investigation into the role of G-CSF in medulloblastoma therapy and methods to specifically target these cells.

Overview and recent advances in the targeting of medulloblastoma cancer stem cells

“…Furthermore, treatment of medulloblastoma cells with chemotherapy followed by G-CSF, mimicking the treatment schema used in patients, led to further increases in the percentage of CD114+ cells. Levels of NRP1 [111], MSI1 [112], TWIST1 [113], MYCN [114] and SOX2 [115] expression were increased in CD114+ cells, supporting an undifferentiated, CSC-like phenotype [110]. G-CSF is used clinically in nearly all children with medulloblastoma in order to manage che-motherapy-induced myelosuppression, raising concern that G-CSF may be supporting the growth of a CSC population.…”

“…CD114 cell surface expression was subsequently demonstrated to be present in a subpopulation of medulloblastoma cells across established cell lines, PDX tumors and patient samples, and CD114+ cells were more resistant to chemotherapy than CD114-cells [110]. CD114+ cells also grew more slowly and responded to G-CSF with increased growth, and the percentages of CD114+ cells were increased after chemotherapy.…”

Individualized discovery of rare cancer drivers in global network context

“…A higher NEA score would indicate that relatively many patient-specific genes were linked to the given pathway. MB cells are known to sometimes produce granulocyte colonystimulating factor (49), which can affect influx of granulocytes (50) and disease prognosis (51). With regard to "Biocarta granulocytes pathway", the MB patients where stratified so that higher DGS scores indicated poorer survival, whereas higher GE.AGS scores were associated with better survival.…”

Contrasting Immunopathogenic and Therapeutic Roles of Granulocyte Colony-Stimulating Factor in Cancer

“…The mechanisms by which G-CSF drives tumor progression vary according to the type of malignancy. For example, in the case of aggressive tumors with high-level expression of G-CSF/G-CSFR, such as breast cancer, gastric and colon cancers, squamous cell cancers of the head and neck and neuroblastoma, data derived from pre-clinical in vitro studies and animal models of tumorigenesis, as well as from histological/genotypic analysis of biopsy specimens from patients, have revealed the existence of autocrine mechanisms of tumor proliferation [ 10 , 80 , 85 , 86 , 87 ]. Intracellular signaling pathways involved in G-CSF/G-CSFR-activated tumor cell proliferation were, however, found to vary somewhat between tumor types.…”

“…Intracellular signaling pathways involved in G-CSF/G-CSFR-activated tumor cell proliferation were, however, found to vary somewhat between tumor types. These mechanisms included the JAK/STAT pathway in the case of neuroblastoma cell lines [ 86 , 87 ] and the ERK1/2 and p90 ribosomal S6 kinase 1 pathways in gastric and colorectal cancer cell lines [ 80 ].…”