Targeting the NG2/CSPG4 Proteoglycan Retards Tumour Growth and Angiogenesis in Preclinical Models of GBM and Melanoma

Abstract

Aberrant expression of the progenitor marker Neuron-glia 2 (NG2/CSPG4) or melanoma proteoglycan on cancer cells and angiogenic vasculature is associated with an aggressive disease course in several malignancies including glioblastoma multiforme (GBM) and melanoma. Thus, we investigated the mechanism of NG2 mediated malignant progression and its potential as a therapeutic target in clinically relevant GBM and melanoma animal models. Xenografting NG2 overexpressing GBM cell lines resulted in increased growth rate, angiogenesis and vascular permeability compared to control, NG2 negative tumours. The effect of abrogating NG2 function was investigated after intracerebral delivery of lentivirally encoded shRNAs targeting NG2 in patient GBM xenografts as well as in established subcutaneous A375 melanoma tumours. NG2 knockdown reduced melanoma proliferation and increased apoptosis and necrosis. Targeting NG2 in two heterogeneous GBM xenografts significantly reduced tumour growth and oedema levels, angiogenesis and normalised vascular function. Vascular normalisation resulted in increased tumour invasion and decreased apoptosis and necrosis. We conclude that NG2 promotes tumour progression by multiple mechanisms and represents an amenable target for cancer molecular therapy.

Prognostic relevance of NG2/CSPG4, CD44 and Ki-67 in patients with glioblastoma

“…The pilot experiments show that abrogating NG2 function with lentivirally encoded shRNAs targeting NG2 in two heterogeneous GBM xenografts significantly reduces tumour growth, oedema and angiogenesis and normalises vascular function, supporting NG2 as a perspective target for cancer molecular therapy. 18 Targeting glioblastoma with natural killer (NK) cells and mAb against NG2/CSPG4 in animal model in vivo prolongs animal survival and demonstrate a proof of concept that this antibody may hold potential for the treatment of GBM. 17 Further studies on diagnostic and therapeutic potential of NG2 for patient stratification and treatment are a perspective direction for future research.…”

NG2 proteoglycan-dependent recruitment of tumor macrophages promotes pericyte-endothelial cell interactions required for brain tumor vascularization

“…However, the proteoglycan is also expressed by tumor cells in several types of cancer, including melanoma, [41][42][43][44] glioblastoma, 38,45,46 sarcoma, 47 myeloid leukemia, 48 and triple-negative breast cancer. 49 In all cases, increased NG2 expression by tumor cells is associated with enhanced tumor progression and worsened patient prognosis.…”

NK Cells with KIR2DS2 Immunogenotype Have a Functional Activation Advantage To Efficiently Kill Glioblastoma and Prolong Animal Survival

“…Formalin-fixed paraffin-embedded sections of the animals' brains were subjected to IHC staining using standard procedures (25). Following unmasking of antigenic determinants, the sections were labeled with the following primary Abs: mouse anti-human nestin (Millipore, Oslo, Norway), mouse anti-human STEM121 (StemCells, Cambridge, U.K.), mouse antihuman NKp46 (BioLegend, San Diego, CA), mouse anti-human Ki-67 (Dako, Glostrup, Denmark), and rat anti-mouse CD31 (Dianova, Hamburg, Germany).…”

“…The percentages of Ki-67 + cells (Ki-67 labeling index) and NKp46 + cells were quantified in five randomly selected high-power (4003 magnification) microscopic fields in all animals in the study group. Detection of apoptotic cells was performed with the TUNEL assay, according to the manufacturer's instructions (Roche Applied Bioscience, Mannheim, Germany), and apoptotic cells were quantified as previously described (25). Quantification of CD31 + microvascular density and area fraction of CD31 + cells was performed as previously described (25).…”