Increased expression of the negative growth factor, galactoside-binding protein, gene in transformed thyroid cells and in human thyroid carcinomas

Murine β-galactoside-binding protein has been shown to be a cell growth regulatory molecule and a cytostatic factor. We analysed the β-galactoside-binding protein gene expression in a thyroid cell system including two normal cell lines (FRTL-5 and PC Cl 3) and the same cells transtected by several oncogenes that induce different degrees of malignancy and differentiation. We show that β-galactoside-binding protein mRNA levels correlate with the expression of the malignant phenotype. Run-on experiments suggest that a transcriptional effect accounts at least in part for such a difference