Reduced Serum Selenoprotein P Concentrations in German Prostate Cancer Patients

Abstract

Selenium (Se) is essentially needed for the biosynthesis of selenoproteins. Low Se intake causes reduced selenoprotein biosynthesis and constitutes a risk factor for tumorigenesis. Accordingly, some Se supplementation trials have proven effective to reduce prostate cancer risk, especially in poorly supplied individuals. Because Se metabolism is controlled by selenoprotein P (SEPP), we have tested whether circulating SEPP concentrations correlate to prostate cancer stage and grade. A total of 190 men with prostate cancer (n = 90) and "no evidence of malignancy" (NEM; n = 100) histologically confirmed by prostate biopsy were retrospectively analyzed for established tumor markers and for their Se and SEPP status. Prostate specific antigen (PSA), free PSA, total Se, and SEPP concentrations were determined from serum samples and compared with clinicopathologic parameters. The diagnostic performance was analyzed with receiver operating characteristic curves. Median Se and SEPP concentrations differed significantly (P < 0.001) between the groups. Median serum Se concentrations in the 25th to 75th percentile were 95.9 μg/L (82-117.9) in NEM patients and 81.4 μg/L (67.9-98.4) in prostate cancer patients. Corresponding serum SEPP concentrations were 3.4 mg/L (1.9-5.6) in NEM and 2.9 mg/L (1.1-5.5) in prostate cancer patients. The area under the curve (AUC) of a marker combination with age, PSA, and percent free PSA (%fPSA) in combination with the SEPP concentration, yielded the highest diagnostic value (AUC 0.80) compared with the marker combination without SEPP (AUC 0.77) or %fPSA (AUC 0.76). We conclude that decreased SEPP concentration in serum might represent an additional valuable marker for prostate cancer diagnostics. (Cancer Epidemiol Biomarkers Prev 2009;18(9):2386-90)

Effects of Selenium Status and Polymorphisms in Selenoprotein Genes on Prostate Cancer Risk in a Prospective Study of European Men

“…The high response rates achieved during the three completed follow-up rounds (>90%) of the EPIC-Heidelberg cohort minimize the risk of selection bias. However, a limitation of our study is the relatively short follow-up time; thus, we cannot rule out that subclinical prostate cancer at baseline might have affected Se status, an influence which was indicated recently in a case-control study of German men (51). Therefore, we repeated analysis after exclusion of all cases (and matched controls) diagnosed within the first year of follow-up, but still found similar results.…”

Prostate Disease Risk Factors among a New Zealand Cohort

“…Although there is controversy over the effect of Se supplementation as a prostate cancer preventative [9,13], our study has shown a significant difference in serum Se level among both prostate cancer patients (101.2 ng/ml) and those with benign prostate disease (100.7 ng/ml) compared to controls (112.9 ng/ml). According to Meyer et al [33], both serum Se and selenoprotein levels are lower among those with prostate cancer, while Steinbrecher et al [34] have shown that the OR for prostate cancer is 0.89 for each 10-µg/l increment in serum Se. According to Marshall et al [35], Se supplementation for those with high-grade prostatic intraepithelial neoplasia by way of 200 µg/day selenomethionine for 3 years has produced a non-significant decrease in prostate cancer incidence only among those in the lowest tertile of plasma Se equivalent to 106 ng/ml.…”

Selenoprotein P Status Correlates to Cancer-Specific Mortality in Renal Cancer Patients

“…After sample collection, the sera had been stored in aliquots at −80°C and were analyzed retrospectively. Sample size determinations and power calculations were based on our previous study results on SePP concentrations in prostate cancer [25] assuming a two-sided alpha error of 5% and a power of 80% for changes of 1 SD between control and RCC subjects. Under these assumptions, a sample size of 32 subjects (16 controls and 16 patients) was calculated as the minimum needed for our study.…”

“…We have recently compared serum Se and SePP concentrations in prostate cancer patients, verifying that both parameters correlate reliably in Se-deficient individuals and may improve prostate cancer diagnosis [25]. Now, we took advantage of a serum bank of renal cell carcinoma (RCC) patients collected at the time of cancer diagnosis and stored deep frozen over more than 60 months.…”