Compared with vector-alone control cells, BLU stable transfectants, derived from poorly-differentiated NPC HONE1 cells, suppress VEGF165, VEGF189 and TSP1 expression at both the RNA and protein levels, and significantly reduce the secreted VEGF protein in these cells, reflecting an unknown regulatory mechanism mediated by the BLU gene in NPC.
To elucidate the role of BLU in tumorigenesis, we analysed BLU promoter methylation status in tumour cell lines and detected promoter region hypermethylation in 39% lung, 42% breast, 50% kidney, 86% neuroblastoma and 80% nasopharyngeal (NPC) tumour cell lines.
The high incidence of BLU alterations suggests that it may be one of the critical tumor suppressor genes on chromosome 3p21.3 involved in the development of NPC.