Changes in gene expression during the growth arrest of HepG2 hepatoma cells induced by reducing agents or TGFβ1

Abstract

The growth of hepatoma cells can be inhibited by treatment with TGFb1 or with exogenous reducing agents. To gain information on the molecular mechanisms underlying growth arrest, we visualized and compared gene expression pro®les of proliferating versus non proliferating HepG2 cells by computer-assisted gene ®shing, an improved technique of RNA ®ngerprinting that allows the selective ampli®cation of coding regions within transcripts. While many transcripts are selectively regulated by either treatment, a set of bands appear to be coordinately regulated by 2ME and TGFb1, suggesting their possible involvement in the mechanisms of growth arrest. Display tags corresponding to 18 di erentially expressed genes were cloned and, in most cases, identi®ed as known genes or, more frequently, as their homospeci®c/cross-speci®c homologues. A novel member of the kinesin superfamily was identi®ed amongst the genes induced by both 2ME and TGFb1. This gene, KIF3C, is upregulated in several cell lines undergoing growth arrest. Taken together, our ®ndings show that computer-assisted gene ®shing is a powerful tool for the identi®cation and cloning of genes involved in the control of cell proliferation and indicate that extracellular reducing agents can regulate cell growth through modulation of gene expression.

Endoplasmic Reticulum Oxidoreductin 1-Lβ (ERO1-Lβ), a Human Gene Induced in the Course of the Unfolded Protein Response

“…Analysis of mRNA by Dot and Northern Blotting-Total cellular RNA preparations and Northern blot analysis were carried out as described previously (29).…”

ERdj5, an Endoplasmic Reticulum (ER)-resident Protein Containing DnaJ and Thioredoxin Domains, Is Expressed in Secretory Cells or following ER Stress

“…Total cellular RNA preparation and Northern blot analysis were carried out as described previously (27). To induce the UPR or unrelated stress response, cells were cultured for 6 h in the presence of dithiothreitol (2 mM), tunicamycin (10 g/ml), thapsigargin (2 M), A23187 (2 M), EGTA (2 mM), or deoxyglucose (10 mM); deprived of fetal calf serum; UV light-irradiated; or incubated at 42°C for 30 min.…”

cDNA microarray gene expression profiling of hydroxyurea, paclitaxel, and p‐anisidine, genotoxic compounds with differing tumorigenicity results

“…Although a total of 19 genes were specifically responsive to genotoxicity, the vast majority of the mouse genome appeared to be unresponsive to chemical stress. In fact, previous analyses indicate that no more than 2% of the human genome is responsive to toxic stress [Cabibbo et al, 1998]. The highest estimate is in the range of 2% of human genome or ϳ2,000 genes and the lowest may only be a few hundred genes [Farr and Dunn, 1999].…”