Correlations of SELENOF and SELENOP genotypes with serum selenium levels and prostate cancer

Background

Selenium status is inversely associated with the incidence of prostate cancer. However, supplementation trials have not indicated a benefit of selenium supplementation in reducing cancer risk. Polymorphisms in the gene encoding selenoprotein 15 (SELENOF) are associated with cancer incidence/mortality and present disproportionately in African Americans. Relationships among the genotype of selenoproteins implicated in increased cancer risk, selenium status, and race with prostate cancer were investigated.

Methods

Tissue microarrays were used to assess SELENOF levels and cellular location in prostatic tissue. Sera and DNA from participants of the Chicago‐based Adiposity Study Cohort were used to quantify selenium levels and genotype frequencies of the genes for SELENOF and the selenium‐carrier protein selenoprotein P (SELENOP). Logistic regression models for dichotomous patient outcomes and regression models for continuous outcome were employed to identify both clinical, genetic, and biochemical characteristics that are associated with these outcomes.

Results

SELENOF is dramatically reduced in prostate cancer and lower in tumors derived from African American men as compared to tumors obtained from Caucasians. Differing frequency of SELENOF polymorphisms and lower selenium levels were observed in African Americans as compared to Caucasians. SELENOF genotypes were associated with higher histological tumor grade. A polymorphism in SELENOP was associated with recurrence and higher serum PSA.

Conclusions

These results indicate an interaction between selenium status and selenoprotein genotypes that may contribute to the disparity in prostate cancer incidence and outcome experienced by African Americans.

     

The relationship between pre-radiation therapy testosterone levels and prostate cancer aggressiveness

We investigated whether there is an association between testosterone levels and prostate cancer aggressiveness in patients treated with radiation therapy who underwent a prostatectomy or prostate radiotherapy (EBRT). A total of 380 patients who received primary or post-operative radiotherapy were identified. At the time of radiotherapy, baseline testosterone levels and body mass index (BMI) measurements were available. On multivariate analysis (MVA), higher prostate-specific antigen (PSA) levels were predictive of testosterone ≥10.4  (OR = 1.3, p = .04) and testosterone ≥12.0 nmol/L (OR = 1.3, p = .04). Patients with a Gleason score ≥8 were more likely to have testosterone <8 nmol/L than patients with a lower score (31% vs. 20%, p = .043). On univariate analysis, a Gleason score ≥8 was associated with a lower likelihood of having a normal (≥8 nmol/L) testosterone level (OR = 0.51, 95% CI: 0.3–0.9, p = .02), and on MVA adjusted for post-surgical versus primary EBRT and BMI (≥30 kg/m²), the Gleason score lost its statistical significance (p = .09). While higher PSA levels are associated with higher testosterone levels, the interaction between Gleason score and testosterone is unclear and merits further study.     

Association between prostate cancer and serum testosterone levels

BACKGROUND: The purpose of the current study was to determine whether the presence of prostate cancer altered serum testosterone levels. METHODS: Initially, we evaluated both serum total and free testosterone levels in patients with either high-grade (n = 18) or moderate-grade (n = 146) prostate cancer, detected by prostate needle biopsies. Then both serum total and free testosterone levels, before and after prostatectomy, were compared in 79 of the 164 men with prostate cancer. RESULTS: In the first setting, serum total and free testosterone levels (307 +/- 24 ng/dl and 1.14 +/- 0.09 ng/dl) in patients with high-grade prostate cancer were significantly lower than those in patients with moderate-grade prostate cancer (452 +/- 12 ng/dl and 1.51 +/- 0.04 ng/dl) and those without prostate cancer (451 +/- 17 ng/dl and 1.55 +/- 0.06 ng/dl). After prostatectomy in 79 patients with prostate cancer, serum levels of both total and free testosterone (511 +/- 15 ng/dl and 1.78 +/- 0.05 ng/dl) were found significantly elevated when compared with their respective presurgical total and free testosterone levels (450 +/- 17 ng/dl and 1.60 +/- 0.06 ng/dl). CONCLUSION: Our findings show that serum total and free testosterone levels in patients with prostate cancer are altered, supporting the possibility that prostate cancer may inhibit serum testosterone levels.     

Selenium supplementation,baseline plasma selenium status and incidence of prostate cancer: an analysis of the complete treatment period of the Nutritional Prevention of Cancer Trial

OBJECTIVE: To present the results (to January 1996, the end of blinded treatment) of the Nutritional Prevention of Cancer (NPC) Trial, a randomized trial of selenium (200 micro g daily) designed to test the hypothesis that selenium supplementation (SS) could reduce the risk of recurrent nonmelanoma skin cancer among 1312 residents of the Eastern USA. MATERIALS AND METHODS: Original secondary analyses of the NPC to 1993 showed striking inverse associations between SS and prostate cancer incidence. A subsequent report revealed that this effect was accentuated among men with the lowest baseline plasma selenium concentrations. The effects of treatment overall and within subgroups of baseline prostate-specific antigen (PSA) and plasma selenium concentrations were examined using incidence rate ratios and Cox proportional hazards models. RESULTS: SS continued to significantly reduce the overall incidence (relative risk and 95% confidence interval) of prostate cancer (0.51, 0.29-0.87). The protective effect of SS appeared to be confined to those with a baseline PSA level of 相似文献   

Association among plasma 1,25(OH)2D,ratio of 1,25(OH)2D to 25(OH)D,and prostate cancer aggressiveness

Background

African-American (AA) men tend to present with more aggressive prostate cancer (Gleason score >7) than European-American (EA) men. Vitamin D and its metabolites are implicated in prostate cancer biology with vitamin D deficiency, indicated by its metabolite levels in serum or plasma, usually observed in AA men.

Objective

To determine if 1, 25-dihydroxy vitamin D3 [1,25(OH)₂D] plasma levels in AA and EA prostate cancer patients alter the risk of having aggressive prostate cancer.

Design

Research subjects from the North Carolina-Louisiana Prostate Cancer Project (AA n = 435 and EA n = 532) were included. Plasma metabolites 1,25(OH)₂D and 25-hydroxyvitamin D3 [25(OH)D] were measured using liquid chromatography with tandem mass spectrophotometry. Research subjects were classified into low (Gleason sum < 7, stage T1-T2, and Prostate-specific antigen (PSA) < 9 ng/mL) or high (Gleason sum > 8 or Gleason sum = 7 with 4 + 3, or PSA > 20 ng/mL, or Gleason sum = 7 and stage T3-T4) aggressive disease.

Results

Research subjects in the second and third tertiles of plasma levels of 1, 25(OH)₂D had lower odds of high aggressive prostate cancer (AA [OR_T2vsT1: 0.66, 95%CI: 0.39-1.12; OR_T3vsT1: 0.83, 95%CI: 0.49-1.41] and EA [OR_T2vsT1: 0.68, 95%CI: 0.41-1.11; OR_T3vsT1: 0.67, 95%CI: 0.40-1.11]) compared with the first tertile, though confidence intervals included the null. Greater 1,25(OH)₂D/25(OH)D molar ratios were associated with lower odds of high aggressive prostate cancer more evidently in AA (OR_Q4vsQ1: 0.45, CI: 0.24-0.82) than in EA (OR_Q4vsQ1: 0.64, CI: 0.35-1.17) research subjects.

Conclusions

The 1,25(OH)₂D/25(OH)D molar ratio was associated with decreased risk of high aggressive prostate cancer in AA men, and possibly in EA men. Further studies analyzing vitamin D polymorphisms, vitamin D binding protein levels, and prostatic levels of these metabolites may be useful. These studies may provide a better understanding of the vitamin D pathway and its biological role underlying health disparities in prostate cancer.

     

Prostate cancer and genetic susceptibility: a genome scan incorporating disease aggressiveness

BACKGROUND: Prostate cancer is a heterogeneous disease, both genetically and phenotypically. Linkage studies attempting to map genes for hereditary prostate cancer (HPC) have proved challenging, and one potential problem contributing to this challenge is the variability in disease phenotypes. METHODS: We collected clinical data on 784 affected men with prostate cancer from 248 HPC families for whom a genomic screen was performed. Disease characteristics (i.e., Gleason score, stage, prostate-specific antigen (PSA)) were used to classify affected men into categories of clinically insignificant, moderate, or aggressive prostate cancer. To potentially enrich for a genetic etiology, we restricted linkage analyses to only men with aggressive disease, although we used genotype information from all family members; linkage analyses used both dominant and recessive models. In addition, subset analyses considered age at diagnosis, number of affected men per family and other stratifications to try to increase genetic homogeneity. RESULTS: Several regions of interest (heterogeneity LOD score, HLOD>1.0) were identified in families (n=123) with >or=2 affecteds with aggressive prostate cancer. "Suggestive" linkage was observed at chromosome 22q11.1 (Dominant model HLOD=2.18) and the result was stronger (Dominant HLOD=2.75) in families with evidence of male-to-male transmission. A second region at 22q12.3-q13.1 was also highlighted (Recessive model HLOD=1.90) among men with aggressive disease, as was a region on chromosome 18. CONCLUSIONS: These analyses suggest that using clinically defined phenotypes may be a useful approach for simplifying the locus heterogeneity problems that confound the search for prostate cancer susceptibility genes.     

Is statin use associated with prostate cancer aggressiveness?

Study Type – Therapy (case series)
Level of Evidence 4

OBJECTIVE

To further examine the association between statins (3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibitors) and pathological features in a large group of patients undergoing radical prostatectomy (RP), as epidemiological studies have suggested that statins, in addition to their beneficial cardiovascular effects, might reduce the risk of aggressive prostate cancer.

PATIENTS AND METHODS

From 2003 to 2009, 1351 men with data on preoperative statin use had RP by one surgeon. The clinical and pathological tumour features were compared between 504 users of statins and 847 who were not users.

RESULTS

Statin users were significantly older and had a higher mean body mass index than non‐users. The preoperative serum prostate‐specific antigen levels, tumour volume and percentage of cancer in the RP specimen were significantly lower in patients taking statins. Overall, statin users had a proportionately lower rate of adverse tumour pathology features, including a significantly lower risk of positive (cancerous) surgical margins.

CONCLUSION

Our results suggest that the use of statins might be associated with more favourable pathological features at RP. The long‐term disease‐specific outcomes and the underlying link between statins and prostate cancer require further investigation.     

Monomethylated selenium inhibits growth of LNCaP human prostate cancer xenograft accompanied by a decrease in the expression of androgen receptor and prostate-specific antigen (PSA)

OBJECTIVES: Epidemiological studies and prevention trials suggest selenium is a promising preventive agent for prostate cancer. Selenium-containing compounds inhibited the growth of prostate cancer cell lines including androgen sensitive LNCaP and androgen insensitive DU145 and PC3 cells in vitro. Previous study revealed a novel mechanism of selenium action in which selenium (methylseleninic acid (MSA)) markedly reduced androgen receptor (AR) signaling in prostate cancer cells, suggesting that selenium might act as an antiandrogen, which could serve as a therapeutic agent for prostate cancer. In this study, we tested whether selenium (methylselenocysteine (MSC)) affects tumor growth of human prostate cancer cells by targeting AR signaling in vivo. METHODS: Prostate tumor xenografts were established in nude mice by co-inoculating LNCaP cells with Matrigel. The mice-bearing tumors were treated with or without MSC (100 microg/mouse/day) via intraperitoneal injection for 2 weeks. The effect of MSC on tumor growth, AR, and prostate-specific antigen (PSA) expression was examined. RESULTS: Methylselenocysteine (MSC) significantly inhibited LNCaP tumor growth (P < 0.05). AR expression in tumor tissues and serum PSA levels were considerably decreased in MSC-treated mice compared to the vehicle controls. CONCLUSIONS: Pharmacological dose of MSC inhibits the growth of LNCaP human prostate cancer in vivo accompanied by a decrease in the expression of AR and PSA. These findings suggest that selenium (MSC) can serve as a therapeutic agent aimed at disruption of AR signaling for prostate cancer.