Cooperation of bcl-2 and myc in the neoplastic transformation of normal rat liver epithelial cells is related to the down-regulation of gap junction-mediated intercellular communication.
The objectives of this study were to isolate several rat liver epithelial cell clones containing the human bcl-2 and myc/bcl-2 genes in order to study their potential cooperative effect on neoplastic transformation and gap junction-mediated intercellular communication (GJIC) and to test the hypothesis that the loss of GJIC leads to tumorigenesis. Using anchorage-independent growth as a surrogate marker for neoplastic transformation, we transfected both normal rat liver epithelial cells, WB-F344, and a WB-F344 cell line overexpressing v-myc with human bcl-2 cDNA. Those cell lines that only expressed v-myc or human bcl-2 were unable to form colonies in soft agar. However, those cell lines that overexpressed both v-myc and human bcl-2 showed varying ability to form colonies in soft agar, which did not correlate with their human bcl-2 expression level. In order to test if there was a correlation between cell line growth in soft agar and the ability to communicate through gap junctions, we performed scrape load dye transfer and fluorescence recovery after photobleaching assays. Our results show that v-myc and human bcl-2 can cooperate in the transformation of normal cells, but the degree to which the cells are transformed is dependent on the cells' ability to communicate through gap junctions.
National Food Safety and Toxicology Center, Department of Pediatrics and Human Development and Genetics Program, East Lansing, MI 48824, USA.
N D
ND
DeoCampo
M R
MR
Wilson
J E
JE
Trosko
D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion / Q000502:physiology; D002450:Cell Communication / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology*; D002999:Clone Cells; D015536:Down-Regulation / Q000502:physiology; D004847:Epithelial Cells / Q000473:pathology / Q000502:physiology; D017629:Gap Junctions / Q000235:genetics / Q000502:physiology*; D019254:Genes, bcl-2 / Q000502:physiology*; D016259:Genes, myc / Q000502:physiology*; D006801:Humans; D008099:Liver / Q000473:pathology* / Q000502:physiology; D014411:Neoplastic Stem Cells / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D014162:Transfection