Role Of Prostate Specific Membrane Antigen And Pepsinogen C Tissue Expression As An Adjunctive Method To Prostate Cancer Diagnosis

In the February 2009 issue of the Journal of Urology, Dr. Alberto Antunes and colleagues from Sao Paulo, Brazil reported on the use of a gene microarray to identify an expression profile that may improve the ability to diagnose prostate cancer (CaP).

The study included tissue from 50 patients who underwent surgery between 1997 and 2000. Two study groups were established; group 1 was comprised of CaP tissue from 33 patients and a control group of 9 patients treated surgically for BPH and group 2 consisted of BPH tissue from 17 men who had CaP and a control of 9 patients with BPH. RNA was extracted from frozen tissue and synthesis of cDNA was performed by reverse transcription. Six previously identified genes were chosen for study; PSMA, TMEFF2, GREB1, TH1L, IGH3 and PGC. These genes were selected from 4,147 genes with different expressions related to the presence of CAP and/or the presence of androgen receptor pathways. RT-PCR was used to analyze the cDNA relative expression. PSMA is a type II membrane protein with high expression in CaP. PGC is an aspartic acid proteinase expressed by gastric tissue, but also expressed in cancers. It is associated with favorable clinical outcomes.

PSMA was always overexpressed (a mean of 9 fold) and PGC was always underexpressed (a mean of 1.3 x 10-4 fold) in CaP compared to BPH cases. The other 4 genes did not express a pattern that differentiated between CaP and BPH tissue. PSMA expression was statistically similar among men with stage T2 and T3 tumors, while PGC was underexpressed in stage T3 compared to T2 tumors. Expression stratified by high and low Gleason score was statistically similar for both genes. In the second group, similar results to the first group were validated.

The potential for clinical utility is to use a gene expression profile such as this to help stratify patients for the likelihood of having prostate cancer. This approach may be especially useful for patients with an elevated PSA and a negative initial biopsy.

Antunes AA, Leite KR, Sousa-Canavez JM, Camara-Lopes LH, Srougi M
J Urol. 2009 Feb;181(2):594-600
doi:10.1016/j.juro.2008.10.007

Written by disease4info.blogspot.com Contributing Editor Christopher P. Evans, MD, FACS