Neuregulin 2 (NRG2) is expressed in gliomas and promotes migration of human glioma cells.

INTRODUCTION: Glioma is the most common primary brain tumour in adults. Numerous studies have shown that neuregulins (NRGs) may be involved in the formation of glioma. Although NRG1 has been extensively studied in glioma, the functions of NRG2 in glioma development remain elusive. MATERIAL AND METHODS: In the present study, we investigated the expression of NRG2 in different grades of human glioma samples, and analysed the functional effects of NRG2 in glioma cells mainly using wound healing assay and transmigration assay. RESULTS: We found that NRG2 was differentially expressed in different grades of human glioma/glioblastoma tissues. The data from wound healing assays demonstrated that NRG2 can differentially promote the migration of SHG44 human glioma, and U251 and U-87 MG human glioblastoma cells at different time points. The results of cell transmigration assays showed that, compared with the vehicle control, the number of cells that migrated to the underside of the insert was increased significantly for all the 3 cell lines treated with 5 nM of NRG2 for 12 hours. CONCLUSIONS: In conclusion, our results demonstrated that NRG2 is expressed in gliomas to varying extents, and it may play roles in the migration of glioma cells in vitro. These data suggest that treatment targeting NRG2 signalling may partly reverse the migration-based metastasis of glioma cells.

Neuregulin 1 enhances cell adhesion molecule L1 like expression levels and promotes malignancy in human glioma.

Neural cell adhesion molecular L1-like protein (CHL1) is a member of the cell adhesion molecule L1 family and serves an important role in the development and progression of tumors. The cytokine neuregulin 1 (NRG1) has been indicated in the tumorigenesis and promotion of metastasis through the modulation of L1. However, the roles of NRG1 in regulating CHL1 in glioma have not been elucidated. The present study investigated the protein expression levels and roles of CHL1 and the possible correlation between NRG1 and CHL1 protein expression levels in human gliomas, both in vivo and in vitro. Using immunohistochemistry coupled with a human glioma tissue microarray, it was demonstrated that the percentage of CHL1-positive areas was the highest in grade II glioma tissues. Using immunofluorescence staining, a positive correlation was identified between the expression levels of CHL1 and proliferating cell nuclear antigen. In addition, CHL1 downregulation also resulted in increased senescence of U-87 MG human glioblastoma cells. In vitro, administration of NRG1α induced a significant increase in CHL1 protein expression levels in human glioma SHG-44 and U251 cells and in human glioblastoma U-87 MG cells, whereas NRG1ß failed to increase CHL1 expression levels in U251 cells. These findings were further confirmed by the downregulation of NRG1 expression levels using small interfering RNA treatment, which resulted in the reduction of CHL1 protein expression levels in U-87 MG cells. These data indicate that NRG1 can regulate CHL1 protein expression levels in gliomas, that it is correlated with malignancy, and that NRG1 may contribute to malignancy by upregulating CHL1 protein expression levels in glioma/glioblastoma cells.