The interplay of growth differentiation factor 15 (GDF15) expression and M2 macrophages during prostate carcinogenesis

M2 (tumor-supportive) macrophages may upregulate growth differentiation factor 15 (GDF15), which is highly expressed in prostate tumors, but the combined utility of these markers as prognostic biomarkers are unclear. We retrospectively studied 90 prostate cancer cases that underwent radical prostatectomy as their primary treatment and were followed for biochemical recurrence (BCR). These cases also had a benign prostate biopsy at least 1 year or more before their prostate cancer surgery. Using computer algorithms to analyze digitalized immunohistochemically stained slides, GDF15 expression and the presence of M2 macrophages based on the relative density of CD204- and CD68-positive macrophages were measured in prostate: (i) benign biopsy, (ii) cancer and (iii) tumor-adjacent benign (TAB) tissue. Both M2 macrophages (P = 0.0004) and GDF15 (P \u3c 0.0001) showed significant inter-region expression differences. Based on a Cox proportional hazards model, GDF15 expression was not associated with BCR but, in men where GDF15 expression differences between cancer and TAB were highest, the risk of BCR was significantly reduced (hazard ratio = 0.26; 95% confidence interval = 0.09-0.94). In addition, cases with high levels of M2 macrophages in prostate cancer had almost a 5-fold increased risk of BCR (P = 0.01). Expression of GDF15 in prostate TAB was associated with M2 macrophage levels in both prostate cancer and TAB and appeared to moderate M2-macrophage-associated BCR risk. In summary, the relationship of GDF15 expression and CD204-positive M2 macrophage levels is different in a prostate tumor environment compared with an earlier benign biopsy and, collectively, these markers may predict aggressive disease

Racial differences in the systemic inflammatory response to prostate cancer

Systemic inflammation may increase risk for prostate cancer progression, but the role it plays in prostate cancer susceptibility is unknown. From a cohort of over 10,000 men who had either a prostate biopsy or transurethral resection that yielded a benign finding, we analyzed 517 incident prostate cancer cases identified during follow-up and 373 controls with one or more white blood cell tests during a follow-up period between one and 18 years. Multilevel, multivariable longitudinal models were fit to two measures of systemic inflammation, neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR), to determine NLR and MLR trajectories associated with increased risk for prostate cancer. For both measures, we found no significant differences in the trajectories by case/control status, however in modeling NLR trajectories there was a significant interaction between race (white or Black and case-control status. In race specific models, NLR and MLR values were consistently higher over time among white controls than white cases while case-control differences in NLR and MLR trajectories were not apparent among Black men. When cases were classified as aggressive as compared to non-aggressive, the case-control differences in NLR and MLR values over time among white men were most apparent for non-aggressive cases. For NLR among white men, significant case-control differences were observed for the entire duration of observation for men who had inflammation in their initial prostate specimen. It is possible that, among white men, monitoring of NLR and MLR trajectories after an initial negative biopsy may be useful in monitoring prostate cancer risk

Growth and differentiation factor 15 and NF-κB expression in benign prostatic biopsies and risk of subsequent prostate cancer detection

Growth and differentiation factor 15 (GDF-15), also known as macrophage inhibitory cytokine 1 (MIC-1), may act as both a tumor suppressor and promotor and, by regulating NF-κB and macrophage signaling, promote early prostate carcinogenesis. To determine whether expression of these two inflammation-related proteins affect prostate cancer susceptibility, dual immunostaining of benign prostate biopsies for GDF-15 and NF-κB was done in a study of 503 case-control pairs matched on date, age, and race, nested within a historical cohort of 10,478 men. GDF-15 and NF-κB expression levels were positively correlated (r = 0.39; p \u3c 0.0001), and both were significantly lower in African American (AA) compared with White men. In adjusted models that included both markers, the odds ratio (OR) for NF-κB expression was statistically significant, OR =0.87; p = 0.03; 95% confidence interval (CI) =0.77-0.99, while GDF-15 expression was associated with a nominally increased risk, OR =1.06; p = 0.27; 95% CI =0.96-1.17. When modeling expression levels by quartiles, the highest quartile of NF-κB expression was associated with almost a fifty percent reduction in prostate cancer risk (OR =0.51; p = 0.03; 95% CI =0.29-0.92). In stratified models, NF-κB had the strongest negative association with prostate cancer in non-aggressive cases (p = 0.03), older men (p = 0.03), and in case-control pairs with longer follow-up (p = 0.02). Risk associated with GDF-15 expression was best fit using nonlinear regression modeling where both first (p = 0.02) and second (p = 0.03) order GDF-15 risk terms were associated with significantly increased risk. This modeling approach also revealed significantly increased risk associated with GDF-15 expression for subsamples defined by AA race, aggressive disease, younger age, and in case-control pairs with longer follow-up. Therefore, although positively correlated in benign prostatic biopsies, NF-κB and GDF-15 expression appear to exert opposite effects on risk of prostate tumor development