Motility of glioblastoma cells is driven by netrin-1 induced gain of stemness

Abstract

BackgroundGlioblastoma is an untreatable brain cancer. The tumors contain a population of stem-like cells which are highly invasive and resistant to therapies. These cells are the main reason for the lethality of glioblastoma. Extracellular guidance molecule netrin-1 promotes the invasiveness and survival of various cancer cell types. We have previously found that netrin-1 activates Notch signaling, and Notch signaling associates with cell stemness. Therefore, we have here investigated the effects of netrin-1 on glioblastoma pathogenesis and glioblastoma cell stemness.MethodsGlioma tissue microarrays were stained with immunohistochemistry and the results were used to evaluate the association between netrin-1 and survival of glioma patients. The localization of netrin-1 was analyzed utilizing fresh frozen glioblastoma tissues. The glioma cell invasion was investigated using ex vivo glioma tissue cultures and newly established primary cell cultures in 3D in vitro invasion assays. Intracranial mouse xenograft models were utilized to investigate the effects of netrin-1 on glioblastoma growth and invasion in vivo.ResultsNetrin-1 expression associated with poor patient prognosis in grade II-III gliomas. In addition, its expression correlated with the stem-like cell marker nestin. Netrin-1 overexpression in cultured cells led to increased formation of stem-like cell spheroids. In glioblastoma tumor biopsies netrin-1 localized to hypoxic tumor areas known to be rich in the stem-like cells. In xenograft mouse models netrin-1 expression altered the phenotype of non-invasive glioblastoma cells into diffusively invading and increased the expression of glioma stem-like cell markers. Furthermore, a distinct invasion pattern where netrin-1 positive cells were following the invasive stem-like cells was detected both in mouse models and ex vivo human glioblastoma tissue cultures. Inhibition of netrin-1 signaling targeted especially the stem-like cells and inhibited their infiltrative growth.ConclusionsOur findings describe netrin-1 as an important regulator of glioblastoma cell stemness and motility. Netrin-1 activates Notch signaling in glioblastoma cells resulting in subsequent gain of stemness and enhanced invasiveness of these cells. Moreover, inhibition of netrin-1 signaling may offer a way to target stem-like cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-016-0482-0) contains supplementary material, which is available to authorized users.

Prognosis Analysis and Validation of m6A Signature and Tumor Immune Microenvironment in Glioma

“…TAGLN2 is considered as a smooth muscle cytoskeletal protein ( 53 ). It has been proposed to be associated with growth and migration in bladder cancer ( 54 , 55 ), esophageal squamous cell carcinoma ( 56 ), and gliomas ( 57 ). Moreover, it's up-regulation is associated with tumorigenesis and tumor progression ( 54 , 58 ).…”

“…Moreover, it's up-regulation is associated with tumorigenesis and tumor progression ( 54 , 58 ). Silence of TAGLN2 in gliomas cell lines significantly inhibited invasion and tumor growth ( 57 ). Increased expression of TAGLN2 was correlated with deteriorative tumor grade, and the function and regulation made it as a candidate prognostic biomarker ( 57 ).…”

Molecular Mechanisms of Glioma Cell Motility

“…Netrin expression is associated with poor patient prognosis in lower grade gliomas. In GBM cells, elevated netrin expression activates notch signaling, finally resulting in the gain of stemness and enhancement of invasiveness of these cells (135).…”

Brain Tumor Treatment: 2017 Update

“…Grade II-III Low grade/ Anaplastic astrocytoma 1) Netrin-1 2) P2RY12 3) Testin 4) B7-H6 1) gain of stemness marker (Ylivinkka, Sihto et al 2017). 2) microglial astrocytoma marker (Zhu, Kros et al 2017).…”