Transcriptional mechanism of vascular endothelial growth factor-induced expression of protein kinase CßII in chronic lymphocytic leukaemia cells.

ABSTRACT

A key feature of chronic lymphocytic leukaemia (CLL) cells is overexpressed protein kinase CßII (PKCßII), an S/T kinase important in the pathogenesis of this and other B cell malignancies. The mechanisms contributing to enhanced transcription of the gene coding for PKCßII, PRKCB, in CLL cells remain poorly described, but could be important because of potential insight into how the phenotype of these cells is regulated. Here, we show that SP1 is the major driver of PKCßII expression in CLL cells where enhanced association of this transcription factor with the PRKCB promoter is likely because of the presence of histone marks permissive of gene activation. We also show how vascular endothelial growth factor (VEGF) regulates PRKCB promoter function in CLL cells, stimulating PKCß gene transcription via increased association of SP1 and decreased association of STAT3. Taken together, these results are the first to demonstrate a clear role for SP1 in the up regulation of PKCßII expression in CLL cells, and the first to link SP1 with the pathogenesis of this and potentially other B cell malignancies where PKCßII is overexpressed.