THE ACTIVATION OF PROTO-ONCOGENE C-HA-RAS ANDTHE CONTROL OF ITS EXPRESSION IN HUMANSTOMACH CANCER

Activated oncogene c-Ha-ras in stomach cancer tissues was identified by DNA transfection. The point mutations were determined in five DNA samples (from three solid tumors of patients with gastro-carcinoma and two cell lines) out of twelve (eight solid tumors and four cell lines) by the restriction fragment length polymorphysm (RFLP) assay. The expressions of c-Ha-ras were enhanced to higher levels (10-20 times) in two cell lines. The lengths of variable tandem repetition (VTR) sequences downstream from the c-Ha-ras coding region were compared for different DNA samples. Their ability to enhance c-Ha-ras expression and their transforming ability are discussed.