ABSTRACT
<p><b>OBJECTIVE</b>To investigate the changes of CD4 + CD25 + Foxp3 + regulatory T cells in the peripheral blood mononuclear cells (PBMC) and their association with insulin resistance in different stages of prostate cancer (PCa).</p><p><b>METHODS</b>Using flow cytometry, we counted the CD4+ CD25 + Foxp3 + regulatory T cells in the PBMCs of 62 PCa patients (5 cases of TNM stage I, 16 cases of stage II, 21 cases of stage III, and 20 cases of stage IV) and 42 normal healthy controls, and calculated their proportion in the CD4+ T-lymphocytes. We determined the levels of fast blood glucose (FBG) and fast insulin (FINS) for the insulin resistance index (HOMA-IR), obtained the serum IGF-1 level by ELISA, and analyzed the relationship of the count and proportion of CD4+ CD25+ Foxp3+ regulatory T cells with insulin resistance by comparison between the PCa patients and normal healthy controls.</p><p><b>RESULTS</b>Compared with the control group, the PCa patients showed significantly increased HOMA-IR (3.68 ± 1.42 vs 6.68 ± 1.66), decreased level of serum IGF-1 ([164.56 ± 30.58] vs [96.39 ± 21.21] ng/ml), and elevated count ([1.99 ± 0.78 ] x 10(7) vs [3.55 ± 0.29] x 10(7)) and proportion ([5.33 ± 0.65] vs [13.88 ± 0.96]%) of CD4 + CD25 + Foxp3 regulatory T cells in the PBMCs. The TNM stage was correlated positively with the count and percentage of CD4 + CD25+ Foxp3 + regulatory T cells and HOMA-IR, but negatively with the level of serum IGF-1. Meanwhile, the count and percentage of CD4 + CD25 + Foxp3 + regulatory T cells were found to have a positive correlation with HOMA-IR (r = 0.722 and 0.689, P < 0.01) but a negative correlation with the level of serum IGF-1 (r = -0.747 and -0.896, P < 0.01).</p><p><b>CONCLUSION</b>The count and proportion of CD4+ CD25 + Foxp3 + regulatory T cells in the peripheral blood and insulin resistance increase with the elevated stage of PCa. CD4 + CD25 + Foxp3 + regulatory T cells may be involved in the occurrence and progression of PCa by regulating insulin resistance.</p>