Clinical impact of ERG and PTEN status in prostate cancer patients underwent radical prostatectomy

Abstract

Objectives: Phosphate and tensin homolog gene (PTEN) acts as a regulator of PI3-KAkt molecular pathway. ETS Related gene (ERG), an oncogene located in chromosome 21q22.2, is involved in prostate cancer (PCa) by serine 2 (TMPRSS2), a protein encoded by TMPRSS2 gene. The aim of this study is to evaluate the clinical impact of PTEN loss and ERG rearrangement in terms of oncologic results in patients diagnosed with localized PCa who underwent radical prostatectomy. Materials and methods: Prospective data were collected from a total of 74 patients who underwent open radical retropubic prostatectomy for localized PCa and immunohistochemical study was performed in tissue samples. The primary antibodies for anti-ERG antibody as well as anti-PTEN antibody were obtained from DAKO. ERG was considered positive if at least 20% of the evaluated cells were stained at least with medium intensity. PTEN protein loss was considered when the intensity of cytoplasmic and nuclear staining was mild or entirely negative across > 10% of tumor cells. Results: Homogenous loss of PTEN was associated with higher clinical International Society of Urological Pathology (ISUP) grade (p = 0.018) while no statistical significant association was present regarding the presence of ERG rearrangement with either ISUPc or ISUPp. After a median follow up of 34 months, 24 patients developed biochemical recurrence. No statistical significant correlation of ERG status with biochemical recurrence was noted while PTEN was associated with biochemical recurrence development in a statistical significant way. Lastly the combination of PTEN loss with ERG rearrangement presence was detected more often in higher ISUPc and ISUPp as well as biochemical recurrence development, although in a non statistical significant way. Conclusions: Homogenous and heterogenous PTEN loss was associated with biochemical recurrence. No association of ERG and biochemical recurrence was noted. The combination of PTEN loss and ERG rearrangement presented a trend for higher ISUPc and ISUPp as well as biochemical recurrence but not in a statistical significant way.