Background: Cytochrome b5 reductase 2 (CYB5R2) is a potential tumor suppressor that inhibits cell proliferation and motility in nasopharyngeal carcinoma (NPC). Inactivation of CYB5R2 is associated with lymph node metastasis in NPC. This study aimed to explore the mechanisms contributing to the anti-neoplastic effects of CYB5R2.
Methods: Polymerase chain reaction (PCR) assays were used to analyze the transcription of 84 genes known to be involved in representative cancer pathways in the NPC cell line HONE1. NPC cell lines CNE2 and HONE1 were transiently transfected with CYB5R2, and data was validated by real-time PCR. A chick chorioallantoic membrane (CAM) embryo model was implanted with CYB5R2-expressing CNE2 and HONE1 cells to evaluate the effect of CYB5R2 on angiogenesis. An immunohistochemical assay of the CAM model was used to analyze the protein expression of vascular endothelial growth factor (VEGF).
Results: In CYB5R2-transfected NPC cells, PCR assays revealed up-regulated mRNA levels of Fas cell surface death receptor (FAS), FBJ murine osteosarcoma viral oncogene homolog (FOS), phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), integrin beta 3 (ITGB3), metastasis suppressor 1 (MTSS1), interferon beta 1 (IFNB1), and cyclin-dependent kinase inhibitor 2A (CDKN2A) and down-regulated levels of integrin beta 5 (ITGB5), insulin-like growth factor 1 (IGF1), TEK tyrosine kinase (TEK), transforming growth factor beta receptor 1 (TGFBR1), and VEGF. The angiogenesis in the CAM model implanted with CYB5R2-transfected NPC cells was inhibited. Down-regulation of VEGF by CYB5R2 in NPC cells was confirmed by immunohistochemical staining in the CAM model.
Conclusion: CYB5R2 up-regulates the expression of genes that negatively modulate angiogenesis in NPC cells and down-regulates the expression of VEGF to reduce angiogenesis, thereby suppressing tumor formation.