Chondroitin Sulphate Proteoglycan 4 (NG2/CSPG4) Localization in Low- and High-Grade Gliomas

Background: Neuron glial antigen 2 or chondroitin sulphate proteoglycan 4 (NG2/CSPG4) is expressed by immature precursors/progenitor cells and is possibly involved in malignant cell transformation. The aim of this study was to investigate its role on the progression and survival of sixty-one adult gliomas and nine glioblastoma (GB)-derived cell lines. Methods: NG2/CSPG4 protein expression was assessed by immunohistochemistry and immunofluorescence. Genetic and epigenetic alterations were detected by molecular genetic techniques. Results: NG2/CSPG4 was frequently expressed in IDH-mutant/1p19q-codel oligodendrogliomas (59.1%) and IDH-wild type GBs (40%) and rarely expressed in IDH-mutant or IDH-wild type astrocytomas (14.3%). Besides tumor cells, NG2/CSPG4 immunoreactivity was found in the cytoplasm and/or cell membranes of reactive astrocytes and vascular pericytes/endothelial cells. In GB-derived neurospheres, it was variably detected according to the number of passages of the in vitro culture. In GB-derived adherent cells, a diffuse positivity was found in most cells. NG2/CSPG4 expression was significantly associated with EGFR gene amplification (p = 0.0005) and poor prognosis (p = 0.016) in astrocytic tumors. Conclusion: The immunoreactivity of NG2/CSPG4 provides information on the timing of the neoplastic transformation and could have prognostic and therapeutic relevance as a promising tumor-associated antigen for antibody-based immunotherapy in patients with malignant gliomas.

Label-Free Detection of Chondroitin Sulphate Proteoglycan 4 by a Polyaniline/Graphene Nanocomposite Functionalized Impedimetric Immunosensor

The chondroitin sulphate proteoglycan 4 (CSPG4), also known as high molecular weight-melanoma associated antigen (HMW-MAA), is a tumor-associated antigen that is expressed in more than 85% of surgically removed melanoma lesions but has restricted distribution in normal tissues. The diagnostic and therapeutic value of CSPG4 drives a need for sensitive and low-cost detection approaches. To this end, we developed a polyaniline/graphene oxide nanocomposite (PANI@GO) that was electrochemically codeposited on indium tin oxide (ITO) electrode. Glutaraldehyde mediated the covalent immobilization of CSPG4 specific antibody mAbD2.8.5 to construct a CSPG4 immunosensor using cell culture media and cell lysate as samples. The fully assembled impedimetric immunosensor was used to detect CSPG4 in CSPG4-positive cell lines M14/CSPG4 and MV3. No impedance signal changes could be observed from CSPG4-negative cell lines M14 and mAbMk2-23 showing the specificity of the CSPG4-impedimetric immunosensor. This low-cost, simple, and label-free analytical method is an alternative to enzyme-linked immunosorbent assay and flow cytometry in screening of CSPG4 in complex biological samples.