Molecular diagnosis of p53 mutations in gastric carcinoma by touch preparation.

Thirty-one tumor samples from selected cases of gastric carcinoma were analyzed for mutations of the p53 tumor suppressor gene. Template DNA was prepared according to the touch preparation procedure, which allowed us to isolate clusters of neoplastic cells out of a stromal cellular background to be used as a template in the amplification of target exons of the p53 locus. In our present study, by polymerase chain reaction/single strand conformation polymorphism analysis we give evidence of p53 mutations occurring in the DNA-binding core domain of the protein (exons 5 through 9), which are clustered in stages III and IV of the disease (six mutations out of seventeen samples; 35%). No p53 mutations were detected in fourteen gastric cancer samples at I and II stages. Beside the use of conventional molecular scanning procedures, our study proposes the application of the touch preparation method to increase the detection of genetic alterations in human solid tumors.