PCA3 AND TMPRSS2:ERG GENES EXPRESSION IN BIOPSIES OF BENIGN PROSTATE HYPERPLASIA, INTRAEPITHELIAL NEOPLASIA, AND PROSTATE CANCER
Morphological analysis of the biopsies for prostate cancer (PCa) often is a difficult task due to heterogeneity and multifocality of tumors. At the same time, a lot of data exist about the potential molecular genetic markers of PCa. The aim of our study is to determine of PCA3 and TMPRSS2:ERG genes expression in benign hyperplasia (BPH), low and high grade intraepithelial neoplasia (PIN), PCa for revealing of diagnostic value of those genes expression in benign and precancerous changes in prostate. Total RNA was isolated from 53 biopsies, reverse transcription was performed, gene expression was determined by real time PCR (RT-PCR) then deltaCt index was determined as Ct(PCA3) - Ct(KLK3). Average deltaCt and its SD in BPH were 8,28±3,13, low PIN - 8,56±2,64, high PIN -8,98±1,69, PCa - 1,08±2,36. We have demonstarted that deltaCt did not differ in patients with BPH, low and high grade PIN, whereas significantly increased in PCa relative to any of the three groups listed above (p<0.0001). Expression of TMPRSS2:ERG was absent in BPH, PIN, but it was detected in 40% (4/10) of PCa cases. ROC-analysis showed that the AUC (area under ROC-curve with 95% CI, p<0.0001) was 0,98 ± 0,02 in the analysis of a combination of overexpression of PCA3 and TMPRSS2:ERG. Thus, the expression analysis of the PCA3 and chimeric oncogene TMPRSS2:ERG in biopsy cannot be used for differential diagnosis of BPH, low and high grade PIN. However, overexpression of PCA3 and expression of TMPRSS2:ERG are characteristic in PCa. Expression analysis of these genes by the proposed RT-PCR modification at the threshold level deltaCt 3,22 has diagnostic accuracy 90% to detect PCa in biopsy specimens.