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Androgen receptor immunostaining and its tissue distribution in formalin-fixed, paraffin-embedded sections after
M Iwamura1, P A Abrahamsson, C M Benning
1Department of Urology, University of Rochester Medical Center, NY 14642.
Abstract:
We used microwave (MW) oven heat treatment to unmask human androgen receptor (AR) immunostaining in formalin-fixed, paraffin-embedded tissue. Prostate tissue was used as an AR-positive control. Tissue sections were boiled in citrate buffer in a conventional MW oven for 30 min, followed by immunostaining with a validated murine monoclonal antibody (MAb), F39.4.1, raised against a peptide included in the N-terminal domain of the 100 KD human AR. AR immunostaining was localized to the nuclei of prostate secretory epithelial cells but was weak or absent in basal cells and of variable intensity in the stromal cells. Slides exposed to less than 10 min of MW heat treatment or none at all manifested no AR immunoreactivity. Tissue morphology was well preserved. Immunohistochemical determination of AR status in a wide variety of human tissues was consistent with that previously reported by others using frozen sections. MW heat treatment of tissue samples in an excellent method of localizing AR antigenicity, enabling immunohistochemical evaluation of AR status in formalin-fixed, paraffin-embedded material.
Insights
Microwave (MW) oven heat treatment effectively unmasks human androgen receptor (AR) immunostaining in formalin-fixed, paraffin-embedded tissues. This method preserves tissue morphology and enables reliable AR evaluation in various human tissues.
Area of Science:
- Histopathology
- Immunohistochemistry
- Molecular Biology
Background:
- The androgen receptor (AR) plays a crucial role in prostate cancer progression.
- Evaluating AR status is vital for treatment decisions.
- Standard immunohistochemistry methods often fail to detect AR in formalin-fixed, paraffin-embedded (FFPE) tissues.
Purpose of the Study:
- To investigate microwave (MW) oven heat treatment as a method to enhance AR immunostaining in FFPE human tissues.
- To assess the efficacy and reliability of MW heat treatment for AR antigen retrieval.
Main Methods:
- Formalin-fixed, paraffin-embedded human prostate tissue sections were used.
- Tissue sections underwent citrate buffer boiling in a MW oven for 30 minutes.
- Immunostaining was performed using a validated anti-AR monoclonal antibody (MAb), F39.4.1.
Main Results:
- MW oven heat treatment successfully unmasked AR immunostaining, primarily in the nuclei of prostate secretory epithelial cells.
- AR immunoreactivity was weak or absent in basal cells and variable in stromal cells.
- Optimal AR detection required at least 10 minutes of MW heat treatment; shorter durations or no treatment resulted in no immunoreactivity.
- Tissue morphology was well preserved after MW treatment.
- Results were consistent with previous findings using frozen sections.
Conclusions:
- MW oven heat treatment is an effective method for AR antigen retrieval in FFPE tissues.
- This technique enables reliable immunohistochemical evaluation of AR status in FFPE samples.
- MW heat treatment offers a valuable tool for studying AR in various human tissues.