Prostate cancer with different ERG status may show different FOXP3-positive cell numbers

Prostatic carcinoma is the most frequent cancer in males in the Western world. A significant proportion of these cancers have a recurrent translocation involving ETS family genes, which leads to the overexpression of ERG transcription factor. Prostate cancers, which bear this mutation, differ in a number of features, including tumor microenvironment. One of the components of the tumor microenvironment is FOXP3 positive lymphocytes, which may participate in breaking immunosurveillance and promoting tumor growth.

The aim of the study was to analyze the relationships between ERG expression, number of FOXP3 positive cells and other features of the tumor.

The study group consisted of 65 cases. Tissue microarrays composed of 2 mm tissue cores were used for immunohistological evaluation. Immunohistochemistry for ERG and FOXP3 was performed according to the routinely applied protocol. The FOXP3 positive cells were counted and the results were expressed as the number of cells per mm2.

The average number of FOXP3 positive cells was 33.30/mm2 for all cases, 21.43/mm2 for the ERG negative and 42.28/mm2 for the ERG positive group (p < 0.02). There were no significant relationships between FOXP3 positive cell count and any other parameters studied.

Our results suggest that the immune response may differ between ERG negative and ERG positive prostatic carcinomas.