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GSTA1 expression in normal, preneoplastic, and neoplastic human prostate tissue
J K Parsons1, C P Nelson, W R Gage
1The Department of Urology, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
The Prostate
|September 11, 2001
Summary
Glutathione S-transferase alpha 1 (GSTA1) expression is elevated in proliferative inflammatory atrophy (PIA) lesions of the prostate, indicating increased oxidative stress. Low GSTA1 and GSTP1 levels in high-grade prostatic intraepithelial neoplasia (HGPIN) and adenocarcinoma suggest impaired detoxification during prostate carcinogenesis.
Area of Science:
- Oncology
- Biochemistry
- Cellular Biology
Background:
- Glutathione S-transferases (GSTs) are crucial enzymes for detoxifying harmful compounds and protecting against cancer.
- Prostatic adenocarcinoma and high-grade prostatic intraepithelial neoplasia (HGPIN) exhibit a lack of GSTP1 expression, linked to promoter methylation and prostate carcinogenesis.
- Elevated GSTP1 levels in proliferative inflammatory atrophy (PIA) suggest a response to oxidative stress, prompting investigation into other GSTs like GSTA1.
Purpose of the Study:
- To investigate the expression patterns of Glutathione S-transferase alpha 1 (GSTA1) in various prostate tissues, including normal epithelium, PIA, HGPIN, and adenocarcinoma.
- To determine if GSTA1 expression in PIA correlates with increased oxidative stress, as hypothesized.
- To compare GSTA1 expression levels across different prostate pathologies and anatomical zones.
Main Methods:
- Immunohistochemistry was employed to detect GSTA1 expression in 45 formalin-fixed radical prostatectomy specimens.
- A stereological grid point counting method quantified the percentage of GSTA1-positive cells in normal prostate, PIA, HGPIN, and adenocarcinoma.
- Expression levels were analyzed across different prostate anatomical zones: peripheral, central, and transition.
Main Results:
- Normal prostate epithelium showed minimal GSTA1 expression (median 3.0%).
- PIA lesions exhibited significantly elevated GSTA1 expression (median 44%, P <.00001) compared to normal tissue, HGPIN (median 3.8%), and adenocarcinoma (median 3.8%).
- The central prostate zone displayed higher GSTA1 expression (median 20.9%) than the transition (median 0.47%) and peripheral zones (P <.0001).
Conclusions:
- Increased GSTA1 expression in PIA supports the hypothesis of heightened oxidative stress within these lesions.
- The low levels of both GSTA1 and GSTP1 in HGPIN and adenocarcinoma suggest a generalized deficiency in detoxification mechanisms.
- This impaired detoxification capacity may play a significant role in the development of prostate cancer.