Changes in gene expression accompanying chemically-induced malignant transformation of human fibroblasts

Abstract

The modulation of gene expression accompanying neoplastic transformation has been assessed by computerized microdensitometry of autoradiographic patterns of [ ³⁵ S]methionine labeled polypeptides separated by two-dimensional polyacrylamide gel electrophoresis. Nearly 1000 polypeptide species of parent diploid human fibroblasts (KD strain) and clonally-derived malignant fibroblasts (HUT-14 strain) were compared. HUT-14 fibroblasts express a mutation in one of the two functional β-actin genes and possess properties that distinguish them as neoplastic cells. Of the 700 more abundant polypeptides measured, 13 were lost and 14 were gained following this neoplastic transformation. It is estimated that ≦2% of the genes expressing abundant polypeptides were either activated or shut off, but at least 32% were modulated quantitatively as a consequence of this neoplastic transformation. Classes of “highly variable” and “marginally variable” polypeptides were assigned. Among the “highly variable” polypeptides, two related species barely detectable in KD parental cells were synthesized at a 25–31-fold higher rate in the transformed cells, and the cell-associated and extracellular matrix forms of fibronectin were each diminished by >90%. Principles emerging from this study may form a basis for interpretation of the role of individual genes in the expression of neoplastic characteristics in HUT-14 cells.