Frequency of PTEN alterations, TMPRSS2-ERG fusion and their association in prostate cancer.

BACKGROUND

Phosphatase and tensin homolog (PTEN) gene aberration and trans membrane protease, serine 2 (TMPRSS2)-v-ets avian erythroblastosis virus E26 oncogene homolog (ERG) fusion are the most prevalent genomic events in prostate cancer. In this study we aimed to evaluate the frequency of PTEN alteration and TMPRSS2-ERG fusion and possible link between these two biomarkers in Iranian men.

METHODS

We assessed 42 fresh frozen tissue samples of prostate cancer (PCA) obtained by radical prostatectomy, interrogating the TMPRSS2-ERG fusion gene along with PTEN gene status using Real Time PCR and FISH methods.

RESULTS

Using Real Time PCR we identified the TMPRSS2-ERG fusion in 64% (27/42) of tumor samples, which was confirmed by FISH technique, giving 21 positive samples with deletion, suggesting the presence of TMPRSS2-ERG fusion gene. By contrast, PTEN deletion was detected in 52% (11/21) of PCA samples, which all showed low expression in Real Time. Concomitance of PTEN deletion or low expression and TMPRSS2-ERG fusion was present in PCA samples (P=0.005). All of the PTEN deletion samples showed TMPRSS2-ERG fusion, (11/11, 100%) while not all of the TMPRSS2-ERG fusion positive samples showed PTEN deletion. None of 29 cases of BPH and 8 cases of normal zone of tumor tissue showed TMPRSS2-ERG fusion.

CONCLUSIONS

These results indicate that PTEN loss occurs in cooperation with TMPRSS2-ERG fusion in PCA. While the majority of PCA samples harbor TMPRSS2-ERG fusion as well as PTEN gene deletion, normal tissues do not show these molecular aberrations.