[Gene amplification in bladder tumors]

Eight patients with transitional cell bladder carcinoma were analyzed viewing the detection of ras oncogene mutations. This sample was picked out from a preliminary study of 20 cases of transitional cell tumors where complex chromosomal rearrangements were observed in tumors of grade II/III. In this first stage of the study non invasive tumors presented an almost diploid chromosome number while the most infiltrative ones displayed pseudo triploidy, triploidy or tetraploidy. A Subsequent study searched for the mutational frequency of the oncogene n-ras using the knowledge of direct DN sequencing and based on the technology of polymerase chain reaction amplification (PCR) in view to establish a relationship between the mutational frequency and the tumor stage and grade. The wild type allele was present in all the tumors examined. Point mutations were detected in 1/3 of the analyzed samples. These samples displayed a grade II-III histology as opposed to the other tumors. These data appear to indicate that n-ras mutations may be early phenomena in the development and progress of a number of human tumors of the urothelium.