FOXP3+ regulatory T cells in normal prostate tissue,postatrophic hyperplasia,prostatic intraepithelial neoplasia,and tumor histological lesions in men with and without prostate cancer

Background

The tumor promoting or counteracting effects of the immune response to cancer development are thought to be mediated to some extent by the infiltration of regulatory T cells (T_regs). In the present study we evaluated the prevalence of T_reg populations in stromal and epithelial compartments of normal, post atrophic hyperplasia (PAH), prostatic intraepithelial neoplasia (PIN), and tumor lesions in men with and without prostate cancer.

Methods

Study subjects were 102 men consecutively diagnosed with localized prostate cancer undergoing radical prostatectomy and 38 men diagnosed with bladder cancer undergoing cystoprostatectomy without prostate cancer at the pathological examination. Whole mount sections from all patients were evaluated for the epithelial and stromal expression of CD4⁺ T_regs and CD8⁺ T_regs in normal, PAH, PIN, and tumor lesions. A Friedmańs test was used to investigate differences in the mean number of T_regs across histological lesions. Logistic regression was used to estimate crude and adjusted odds ratios (OR) for prostate cancer for each histological area.

Results

In men with prostate cancer, similarly high numbers of stromal CD4⁺ T_regs were identified in PAH and tumor, but CD4⁺ T_regs were less common in PIN. Greater numbers of epithelial CD4+ T_regs in normal prostatic tissue were positively associated with both Gleason score and pT‐stage. We observed a fourfold increased risk of prostate cancer in men with epithelial CD4⁺ T_regs in the normal prostatic tissue counterpart.

Conclusions

Our results may suggest a possible pathway through which PAH develops directly into prostate cancer in the presence of CD4⁺ T_regs and indicate that transformation of the anti‐tumor immune response may be initiated even before the primary tumor is established.