Activated Ki-ras genes in bladder epithelial cell lines transformed by treatment of primary mouse bladder explant cultures with 7,12-dimethylbenz[a]anthracene.
DNA from five lines of transformed bladder epithelial cells derived from cultures of primary cells that had been treated with 7,12-dimethylbenz[a]anthracene (DMBA) can transform NIH 3T3 mouse fibroblasts in DNA transfection experiments. Southern analysis of DNA from NIH 3T3 primary and secondary transformants established that four of the DMBA-transformed cell lines contained activated cellular Ki-ras, while the remaining cell line contained a transforming gene that is unrelated to Ki-ras, N-ras, and Ha-ras. The point mutations responsible for Ki-ras activation were detected using oligonucleotide probes following selective amplification of Ki-ras specific sequences using the polymerase chain reaction. The results showed that activation of Ki-ras invariably involved a GC----AT transition mutation of the first position of codon 12. Surprisingly, a Ki-ras gene that was activated by a GC----AT transition mutation at the same position was also detected in a single transformed bladder urothelial cell line derived from control cultures of mouse bladder cells. Together, our results indicate that Ki-ras activation in the DMBA-transformed bladder cell lines may not be a direct consequence of interaction of activated DMBA metabolites with the Ki-ras gene.
Brookes
P
P
Chemical Carcinogenesis Section, Institute of Cancer Research, London, England.
Cooper
C S
CS
Ellis
M V
MV
Warren
W
W
Gardner
E
E
Summerhayes
I C
IC
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity*; D000818:Animals; D015139:Blotting, Southern; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D006224:Cricetinae; D004247:DNA / Q000187:drug effects / Q000235:genetics; D004252:DNA Mutational Analysis; D004259:DNA-Directed DNA Polymerase; D005786:Gene Expression Regulation / Q000187:drug effects*; D051379:Mice; D015345:Oligonucleotide Probes; D009857:Oncogenes; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D014162:Transfection; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced / Q000235:genetics*
D015345:Oligonucleotide Probes; D011518:Proto-Oncogene Proteins; D015127:9,10-Dimethyl-1,2-benzanthracene; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D016283:Proto-Oncogene Proteins p21(ras)