Androgen Receptor Polymorphism-Dependent Variation in Prostate-Specific Antigen Concentrations of European Men

Mitochondrial determinants of cancer health disparities

Mitochondria, which are multi-functional, have been implicated in cancer initiation, progression, and metastasis due to metabolic alterations in transformed cells. Mitochondria are involved in the generation of energy, cell growth and differentiation, cellular signaling, cell cycle control, and cell death. To date, the mitochondrial basis of cancer disparities is unknown. The goal of this review is to provide an understanding and a framework of mitochondrial determinants that may contribute to cancer disparities in racially different populations. Due to maternal inheritance and ethnic-based diversity, the mitochondrial genome (mtDNA) contributes to inherited racial disparities. In people of African ancestry, several germline, population-specific haplotype variants in mtDNA as well as depletion of mtDNA have been linked to cancer predisposition and cancer disparities. Indeed, depletion of mtDNA and mutations in mtDNA or nuclear genome (nDNA)-encoded mitochondrial proteins lead to mitochondrial dysfunction and promote resistance to apoptosis, the epithelial-to-mesenchymal transition, and metastatic disease, all of which can contribute to cancer disparity and tumor aggressiveness related to racial disparities. Ethnic differences at the level of expression or genetic variations in nDNA encoding the mitochondrial proteome, including mitochondria-localized mtDNA replication and repair proteins, miRNA, transcription factors, kinases and phosphatases, and tumor suppressors and oncogenes may underlie susceptibility to high-risk and aggressive cancers found in African population and other ethnicities. The mitochondrial retrograde signaling that alters the expression profile of nuclear genes in response to dysfunctional mitochondria is a mechanism for tumorigenesis. In ethnic populations, differences in mitochondrial function may alter the cross talk between mitochondria and the nucleus at epigenetic and genetic levels, which can also contribute to cancer health disparities. Targeting mitochondrial determinants and mitochondrial retrograde signaling could provide a promising strategy for the development of selective anticancer therapy for dealing with cancer disparities. Further, agents that restore mitochondrial function to optimal levels should permit sensitivity to anticancer agents for the treatment of aggressive tumors that occur in racially diverse populations and hence help in reducing racial disparities.

Lower prostate cancer risk in Swedish men with the androgen receptor E213 A-allele

Background

In a previous population-based study on 3369 European men with self-reported prostate cancer (PCa), it was shown that androgen receptor (AR) haplotype designated H2 was associated with high levels of serum PSA (prostate-specific antigen) concentration, and, at the same time, with low risk for PCa. The aim of this study was to replicate this finding in other cohorts, with registry-based cancer diagnosis.

Methods

Using data from two population-based cohorts; the Malmö Diet and Cancer Study (MDCS, n = 12,121) and the Swedish Osteoporotic fractures in men study (MrOS, n = 1,120), 628 men with PCa and 1,374 controls were identified and genotyped. PCa data were collected from the Swedish national cancer registry. PCa odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for carriers of the particular AR haplotype, tagged by the rs6624304 T-allele.

Results

The 15% of men who were carriers of the AR haplotype H2 had approximately one-third lower risk for PCa diagnosis compared to those with the most common H1 variant (OR 0.65; 95% CI 0.45–0.94; p = 0.021). The same trend, although not statistically significant (OR 0.75; 95% CI 0.47–1.24; p = 0.275), was observed in MrOS Sweden. When both cohorts were merged, an even more significant result was observed (OR 0.68; 95% CI 0.51–0.90; p = 0.008).

Conclusions

Swedish men with the variant AR haplotype H2, tagged by rs6624304, have significantly lower risk of PCa compared to those with the more common variant.

The androgen receptor gene CAG repeat in relation to 4-year changes in androgen-sensitive endpoints in community-dwelling older European men

CONTEXT

The androgen receptor (AR) gene exon 1 CAG repeat length has been proposed to be a determinant of between-individual variations in androgen action in target tissues, which might regulate phenotypic differences of human ageing. However, findings on its phenotypic effects are inconclusive.

OBJECTIVE

To assess whether the AR CAG repeat length is associated with longitudinal changes in endpoints that are influenced by testosterone (T) levels in middle-aged and elderly European men.

DESIGN

Multinational European observational prospective cohort study.

PARTICIPANTS

A total of 1887 men (mean ± s.d. age: 63 ± 11 years; median follow up: 4.3 years) from centres of eight European countries comprised the analysis sample after exclusion of those with diagnosed diseases of the hypothalamic-pituitary-testicular (HPT) axis.

MAIN OUTCOME MEASURES

Longitudinal associations between the AR CAG repeat and changes in androgen-sensitive endpoints (ASEs) and medical conditions were assessed using regression analysis adjusting for age and centre. The AR CAG repeat length was treated as both a continuous and a categorical (6-20; 21-23; 24-39 repeats) predictor. Additional analysis investigated whether results were independent of baseline T or oestradiol (E₂) levels.

RESULTS

The AR CAG repeat, when used as a continuous or a categorical predictor, was not associated with longitudinal changes in ASEs or medical conditions after adjustments. These results were independent of T and E₂ levels.

CONCLUSION

Within a 4-year time frame, variations in the AR CAG repeat do not contribute to the rate of phenotypic ageing, over and above, which might be associated with the age-related decline in T levels.

Does larger tumor volume explain the higher prostate specific antigen levels in black men with prostate cancer--Results from the SEARCH database

OBJECTIVES

To assess whether larger tumor volume in black men explains higher presurgical PSA levels versus white men with prostate cancer.

METHODS

We retrospectively analyzed 1904 men from the Shared Equal Access Regional Cancer Hospital database who underwent radical prostatectomy from 1990 to 2013. Geometric mean of tumor volume and preoperative PSA for each race were estimated from multivariable linear regression models.

RESULTS

There were 1104 (58%) white men and 800 (42%) black men. Black men were younger (60.2 vs. 62.9 years, p<0.001) had a higher PSA (6.7 vs. 6.0 ng/mL, p<0.001), more positive margins (47 vs. 38%, p<0.001), and seminal vesicle invasion (13 vs. 9%, p=0.007). White patients had higher clinical stage (p<0.001) and greater median tumor volume (6.0 vs. 5.3 gm, p=0.011). After multivariable adjustment (except for PSA), white men had smaller mean tumor volumes (5.2 vs. 5.8 gm, p=0.011). When further adjusted for PSA, there was no racial difference in mean tumor volume (p=0.34). After multivariable adjustment, black men had higher mean PSAs vs. white men (7.5 vs. 6.1 ng/mL, p<0.001). Results were similar after further adjusting for tumor volume: black men had 16% higher mean PSAs versus white men (7.4 vs. 6.2 ng/mL, p<0.001).

CONCLUSIONS

In this study of men undergoing radical prostatectomy at multiple equal access medical centers, racial differences in tumor volume did not explain higher presurgical PSA levels in black versus white men. The exact reason for higher PSA values in black men remains unclear.