Growth factors in expressed prostatic fluid from men with prostate cancer, BPH, and clinically normal prostates

Although growth factors such as epidermal growth factor (EGF), transforming growth factor (TGF)-alpha, and TGF-beta are important regulators of prostate cell growth in vitro and in animal models, evidence to support their role in human prostate cancer development remains sparse. We previously showed that men without prostate cancer have concentrations of EGF and TGF-alpha in expressed prostatic fluid (EPF) that are individually distinct and stable over time. This study addressed whether growth factor levels in EPF are associated with the presence or progression of prostate cancer.

We measured levels of immunoreactive EGF, TGF-alpha, and TGF-beta1 in stored EPF samples from three age-matched groups: 19 men with untreated, histologically diagnosed prostate cancer (CaP), 38 with benign prostate hyperplasia (BPH), and 19 with normal prostate glands (NPD).

Median TGF-alpha was lower in the BPH group (0.45 ng/ml) than in either CaP (0.63 ng/ml) or NPD (0.58 ng/ml) groups (P = 0.03 and 0.12, respectively). For EGF, the median was lowest in the CaP group and highest in the NPD group (92.5 ng/ml vs. 175.5 ng/ml, P = 0.006). For TGF-beta1, the median level in CaP was 2.7 times higher than the median level among all controls (6.65 ng/ml vs. 2.46 ng/ml, P = 0.002). Growth factor levels were not associated with tumor stage or Gleason score. However, the single case with distant metastases had TGF-beta1 levels 23-fold higher than the CaP median.

The results suggest that at the time of CaP diagnosis, EGF levels in EPF are significantly lower, and TGF-beta1 levels significantly higher, than normal. Marked overexpression of TGF-beta1 in advanced CaP might be reflected in extremely high EPF levels.