Demonstration of TMPRSS2-ERG gene fusion by PCR in prostate adenocarcinomas

Demonstratıon Of TMPRSS2:ERG Gene Fusıon By Pcr In Prostate Adenocarcınomas Promoter of TMPRSS2 (transmembrame protease, serine 2) and erythroblastosis virus E6 (Ets) gene family fusion is common in prostate cancer. TMPRSS2 is an androgen regulated serine protease. Ets gene family is a transcription factor including a highly conserved DNA binding domain and Nterminal regulating region. The fusion of these genes lead to androgen regulated Ets factor transcription in prostatic tumor cells. Most common fusion is TMPRSS2-ETS related gene (ERG). ETV1, ETV4, and ETV5 fusions are also identified. Our study consists of 101 patients with mean age of 64 (46-88), mean PSA level of 10,4 (0,6-116,4). Twenty cases had BPH, 31 cases had Gleason score of 6, 25 cases had Gleason score of 7, and 25 cases had Gleason score of 8 or greater. Among the cases involved in the study, 14 with Gleason score of 8 or greater obtained from TUR-P, the rest 87 obtained from radical prostatectomy. TMPRSS2-ERG gene expression was studied by RT-PCR from the paraffin-embedded blocks of our patients. Among the whole 20 cases of BPH, ERG and TMPRSS2 expression was detected in 8 (40%) cases, wasn't detected in the remaining 12 (60%). ERG and TMPRSS2 expression was seen in all the thirty-one cases with Gleason score of 6 (low grade), and 25 cases with Gleason score of 7 (intermediate grade). ERG and TMPRSS2 expression wasn't shown in twenty-five cases with Gleason score of 8 or greater (high grade) (p=0,000). Expression was associated with survey, Gleason score (p<0,05) whereas it didn't show statistically significant association with age and PSA (p>0,05). In our study, we found out that TMPRSS2/ERG expression was positive in the cases who had low Gleason score and peripheral zone tumor. The lack of TMPRSS2/ERG expression in our cases with high Gleason scores makes us to think that this might be due to the fact that these tumors are localised in the transitional zone. The existence of expression in tumors that developed from the peripheral zone, which were usually exemplified with radical prostatectomy, shows that the tumors that develop from the peripheral and transitional zones follow different molecular pathways. Nevertheless, in the first steps of tumor development pathway, expression is more effective, as another possible mechanism is different molecular pathways play role in the further steps.