ABSTRACT
A large number of studies for genes involved in oncogenesis have been done during last decade. Over 20 oncogenes have been isolated characterized, and the oncogene expressions in human tumors have been examined. The proto-oncogenes of c-Myc, c-Fos and c-Jun, which modulate the transcription factors, have overexpressed in a variety of human cancers. Immunohistochemical method was used in this study to examine c-Myc, c-Fos and c-Jun oncoprotein expression in 31 patients with human pheochromocytoma 28(90.0%) were benign and 3(10.0%) malignant. C-Myc oncoprotein immunoreactivity was found in 24 cases(77.4%), c-Fos in 29(93.5%), and c-Jun in 25(80.6%). Twenty-one(67.7%) showed positive immunoreactivity for all these oncoproteins, six(19.4%) for 2 oncoproteins, 3 for one oncoprotein. Only 1 case showed negative immunoreactivity for all 3 oncoproteins. The oncoprotein immunoreactivity did not correlate with the amount of 24 hour urinary catecholamine excretion. Although the number of malignant pheochromocytomsa was not so many, most of them showed that the immunoreactivity for oncoprotein was more than 30 percent of tumor cells.The expression of c-Myc, c-Fos and c-Jun oncoprotein were frequently found in human pheochromocytoma. These results suggest that the oncoprotein expression may play an important role in tumorogenesis and proliferation of human pheochromocytoma.