title: Frequency of active ras oncogenes in human bladder cancers associated with schistosomiasis.
abstract: The frequency of active ras oncogenes in human bladder cancers associated with schistosomiasis, the cause of which is suspected to be a chemical carcinogen(s) in urine, was examined. Of 9 squamous cell carcinomas of the bladder surgically obtained in Egypt, none scored as positive in the regular DNA transfection assay using NIH/3T3 cells as recipients. The restriction fragment length polymorphism assay at codon 12 of the H-ras gene confirmed the absence of an activating mutation at this site in all of them. Western blotting analysis of electrophoretic mobilities of the ras p21 proteins, a method which can detect at least some of the point mutations within codons 12 and 61 of ras genes, suggested a point mutation within codon 61 in one out of the 7 tumors analyzed. In contrast to the low frequency of detection of mutationally activated ras oncogenes, enhanced expression of the ras p21 proteins was demonstrated in 4 of them by this analysis. The carcinogenic process involved in the endemic bilharzial bladder cancers is thus not associated with detectable point mutations within ras genes at a higher frequency than those in non-bilharzial bladder cancers in Japan or the USA.
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000150:complications* / Q000235:genetics; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D005260:Female; D005784:Gene Amplification; D011905:Genes, ras; D006801:Humans; D008297:Male; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000302:isolation & purification; D016283:Proto-Oncogene Proteins p21(ras); D012552:Schistosomiasis / Q000150:complications*; D014162:Transfection; D001749:Urinary Bladder Neoplasms / Q000150:complications* / Q000235:genetics
chemical_list: D011518:Proto-Oncogene Proteins; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)