Rearrangement, amplification and overexpression of c-Ha Ras gene in premalignant lesion of Turcot's syndrome.

Ras gene family (c-Ha, Ki, N ras) and c-myc proto-oncogenes were analyzed in seven colonic and three gastric adenomatous polyps obtained from a patient with Turcot's syndrome. The rearrangement and amplification as well as overexpression of c-Ha ras gene in one colonic adenomatous polyp were determined. The amplified c-Ha ras gene in this polyp revealed larger fragments of BamHI, PstI and SacI than those in the normal colonic mucosa from the same patient. But, such abnormalities were not observed in other polyps. No abnormalities of c-Ki ras, c-N ras or c-myc gene were observed in any polyps. These results suggest that the alternations of c-Ha ras gene in this patient may not be responsible for the adenomatous change, but may be related to the transition from adenoma to carcinoma of the colon.