A role for the NG2 proteoglycan in glioma progression

Abstract

Many human gliomas carry markers characteristic of oligodendrocyte progenitor cells (such as Olig-2, PDGF alpha receptor and NG2 proteoglycan), suggesting these progenitors as the cells of origin for glioma initiation. This review considers the potential roles of the NG2 proteoglycan in glioma progression. NG2 is expressed not only by glioma cells and by oligodendrocyte progenitors, but also by pericytes associated with the tumor microvasculature. The proteoglycan may therefore promote tumor vascularization and recruitment of normal progenitors to the tumor mass, in addition to mediating expansion of the transformed cell population. Along with potentiating growth factor signaling and serving as a cell surface receptor for extracellular matrix components, NG2 also has the ability to mediate activation of b-1 integrins. These molecular interactions allow the proteoglycan to contribute to critical processes such as cell proliferation, cell motility and cell survival.

Extracellular Matrix Microenvironment in Glioma Progression

“…Another member of CSPGs is phosphocan, an astroglial proteoglycan that binds to neural cell adhesion molecules and tenascin-C. Neuroglial protein-2 (NG2), also a CSPG proteoglycan, which is known as a characteristic marker of oligodendrocyte progenitor cells and pericytes in developing vasculature, is expressed by many gliomas. The NG2 positive cells have been suggested to be the originating cells for glioma (Stallcup and Huang 2008). Tenascins (C and R), a family of glycoproteins exist in the ECM as assemblies of several subunits expressed in zones of proliferation, migration, and morphogenesis and are known to play an important role in the developing CNS.…”

Proteoglycans in normal physiology and carcinogenesis

“…Наряду с передачей сигналов от факторов роста NG2 является рецептором клеточной поверхности для ком-понентов ВКМ и β1-интегрина, и его активация вносит свой вклад в такие процессы, как пролиферация кле-ток, их подвижность и жизнеспособность [71]. Экс-прессия NG2 в опухолях головного мозга у детей раз-личается в зависимости от типа, и, в отличие от глиомы у взрослых, NG2 экспрессируется в опухолях более низкой степени злокачественности [72].…”

Systems Biology of Tumor Microenvironment

“…It was found recently that HA and its CD44 receptor may play an important role in the "stemness" and survival of cancer stem cells [4]. In addition, CSPG proteoglycan known as neuroglial protein-2 (NG2) was recognized as a cell biomarker for oligodendrocyte progenitor cells and found in gliomas [11,14], therefore emphasizing the importance of this ECM molecule.…”

“…It was found recently that HA and its CD44 receptor may play an important role in the "stemness" and survival of cancer stem cells [4]. In addition, CSPG proteoglycan known as neuroglial protein-2 (NG2) was recognized as a cell biomarker for oligodendrocyte progenitor cells and found in gliomas [11,14], therefore emphasizing the importance of this ECM molecule.The HSPGs components of the glioma microenvironment are also part of blood vessels and serve as a location for growth factor and cytokine storage, therefore contributing to the creation of a niche in which glioma stem cells can receive signals from its microenvironment [3]. The blood vessels and myelinated nerve fibers which serve as the infiltrative path for disseminating glioma cells have higher rigidity and together with the increased rigidity of ECM contribute to glioma migration [8,12].…”