Expression of Cellular Oncogenes in Human Prostatic Adenocarcinoma and Benign Prostatic Hypertrophy

Lee, Sang Eun; Kim, Wun Jae; Seo, Jeong Sun

Abstract

Carcinogenic agents might convert normal cells into cancer cells by inducing higher levels of normal c-oncogene products or by inducing structurally aberrant gene products. Although the evidence for a causal relation between oncogenes and cancer is only circumstantial, the expression of cellular oncogenes may be of particular interest, since they are differentially expressed in a highly restricted manner. Therefore, we have examined the expression of the cellular oncogenes in order to characterize the possible role of cellular oncogenes in prostatic tumorigenesis and determine whether the level of expression of these genes can help in distinguishing between benign and malignant lesions or in predicting the presence of clinically aggressive disease. We investigated the level of gene expression of 4 c-oncogenes(c-Ha-ras, c-Ki-ras, c-fps, c-myc) in 8 patients with prostatic adenocarcinoma, 5 patients with benign prostatic hypertrophy(BPH) and 1 normal prostate as a control. The results were summarized as follows : 1. More than one c-onc gene was transcriptionally active in 6 of 8 cases with prostatic carcinoma and 3 of 5 cases with BPH. 2. Increased expression of c-myc was observed in 7 of 8 cases(88% ) and increased expression of c-fps was observed in 6 of 8 cases(75%) with prostatic carcinomas. 3. Increased expressions of c-myc and c-fps were observed simultaneously in 3 of 5 cases(60%) with BPH. 4. Both c-Ha-ras and c-Ki-ras were expressed simultaneously in 2 of 8 cases(25%) with prostatic carcinoma and 2 of 5 cases(40% ) with BPH. 5. The coincidence of expression of 2 oncogenes, such as c-myc and c-fps was found in 6 of 7 cases( 86% ) with prostatic carcinoma. 6. There is no significant difference in frequency or level of oncogene expressions between low and high grade tumors(Gleason score < 7 vs > or =7). 7. There is increased incidence of expression of c-Ha-ras and c-Ki-ras in disseminated disease (Stage D) compared to localized pelvic disease(Stage A, B, C), but there is no significant difference in frequency or level of c-fps and c-myc expression between localized pelvic disease and disseminated disease. 8. There is no significant difference in frequency or level of oncogene expressions between prostatic carcinoma and BPH. 9. The prognostic significance of elevated level of c-oncogene expression in prostatic carcinoma warrants further investigation.