DIFFERENTIAL EXPRESSION OF NOVH AND CTGF IN HUMAN GLIOMA CELL-LINES

Aims-(1) To investigate the expression in human derived glioblastoma c ell lines of two structurally related genes, novH (nephroblastoma over expressed gene) and CTGF (connective tissue growth factor), which enco de putative insulin-like growth factor binding proteins of a novel typ e. (2) To investigate whether the same transcription factors regulate CTGF and novH expression. Methods-Expression of novH and CTGF was anal ysed in 24 glioblastoma derived cell lines by northern blotting. The C TGF promoter region was characterised by nucleotide sequencing, RNase protection experiments, by transient transfections, and CAT assays. Re sults-CTGF and novH mRNA levels differed in the glioma cell lines stud ied. NovH and CTGF genes were not coexpressed in all cell lines. The C TGF promoter region was highly conserved compared with the correspondi ng region in the mouse (FISP12) and exhibited in vitro transcriptional activity. Conclusions-Although the coding regions of novH and CTGF ar e highly homologous, their promoter regions are substantially differen t, suggesting that these two genes may be regulated by different mecha nisms, Considering that novH and CTGF are likely to be, respectively, negative and positive regulators of growth and that some glioma cell l ines expressing novH are not tumorigenic, expression of these two gene s might represent a key element in determining the stage of differenti ation or the malignant potential, or both, of some tumour cell lines.