Infiltration of Prostate Cancer by CD204+ and CD3+ Cells Correlates with ERG Expression and TMPRSS2-ERG Gene Fusion

The aim of the study was to detect CD204 + and CD3 + cells in the infiltrate of benign prostatic hyperplasia, prostatic intraepithelial neoplasia and prostatic cancer in prostate specimens after radical prostatectomy. Another goal was to determine correlation of the intensity of the infiltration with ERG oncoprotein expression as well as with the presence of activat-ing translocation TMPRSS2-ERG.

To confirm the translocation, we used fluorescence in situ hybridization. Imunohistochemistry was used to detect the presence of ERG oncoprotein and for assesment of the number of CD204+ and CD3+ infiltrat-ing cells. We determined the capability to infiltrate malignant structures accord-ing to differences in infiltration of benign and malignant prostate structures.

Biometric analysis confirmed that the number of CD204+ macrophages in the malignant structure was significantly higher than in the benign prostatic hyperplasia regardless of the fusion pattern. Increased infiltration by CD3+ cells was only detected in malignant structures of the prostate in a group with normal signal pattern and in a group with TMPRSS2-ERG fusion. Expression of ERG positively correlated with CD204+ and CD3+ cells infiltration of malignant structures only in cases where the TMPRSS2-ERG fusion was found. In the group with a break in the TMPRSS2 gene, a positive correlation was only found between ERG expression and CD204+ macrophages infiltration. In cases with a normal signal pattern, no correlation was found. In the group with TMPRSS2-ERG fusion we observed significantly more cases with a good capability of CD204+ cells to infiltrate malignant structures, unlike the group with a normal signal pattern, where there were more cases with the weak reactivity of CD204 + cells to infiltrate the malignant structures. The same was observed for CD3+ cells. CD204+ macrophages and CD3+ T-lymphocytes in the group with TMPRSS2-ERG gene fusion, infiltrated the malignant prostate structures more intensely, but their effect on malignant transformation may be different.

The association between the presence of the TMPRSS2-ERG fusion and the different capability of inflammatory cells to infiltrate malignant structures has not been reported so far. The results confirm the important role of the activated ERG gene, due to TMPRSS2-ERG fusion, in the development of inflammation of the prostate as well as the effect of inflammatory cells on the course of neoplastic process. This leads to considerations about introduc-ing immunomodulatory modalities into prostate cancer therapeutic protocols. Key words: prostate cancer -  TMPRSS2-ERG gene fusion -  ERG -  immune response -  CD204+ macrophages -  CD3+ T-lymphocytes.