Is neuroglial antigen 2 a potential contributor to cilengitide response in glioblastoma?

Hatice Sevim Nalkiran, Kerrie Leanne McDonald

Journal of Cancer Research and Therapeutics 2017 13(2):329-336

Background: Determining the expression levels of neuroglial antigen 2 (NG2) in glioma cell lines and to evaluate the potential contribution of NG2 to cilengitide response were aimed. Materials and Methods: Endogenous expression level of NG2 was determined using quantitative reverse transcription polymerase chain reaction and immunoblotting. Cilengitide responses of the cells were monitored to determine half maximal inhibitory concentration values. Whether the suppression of NG2 expression alters the response of A172 cells to cilengitide was examined. Results: The effect of cilengitide on inducing apoptosis of the cells was determined by TUNEL staining. High mRNA and protein expression of NG2 was detected in A172 and U-87MG cells, while T98G, M059K and M059J cells demonstrated low levels of NG2. A172, U-87MG and positive control MG-63 were relatively sensitive to cilengitide compared to T98G, M059K and M059J. MG-63, A172 and U-87MG were unexpectedly found to be more susceptible to cilengitide. In addition, NG2 knock-down showed no significant difference in cell death between small interfering RNA (siRNA)-transfected and cilengitide-treated groups. The results showed that cilengitide caused detachment and subsequently initiated apoptosis. Glioma cell lines express variable levels of NG2 and differ in their responses to cilengitide. Although increased numbers of apoptotic cells were found in untransfected cells compared to siRNA-transfected cells upon exposed to cilengitide, the difference was not documented to be significant between two groups. Conclusion: It may be proposed that the combination therapy of NG2 suppression and cilengitide treatment showed no considerable effect on glioblastoma compared to cilengitide therapy alone. Response to therapy may be further improved by targeting other factors act in concert in this signaling pathway.

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