Prostate cancer incidence varies among males from different Y-chromosome lineages

Y Chromosome Genomic Variations and Biological Significance in Human Diseases and Health

The Y chromosome is a haploid genome unique to males with no genes essential for life. It is easily transmitted to the next generation without being repaired by recombination, even if a major genomic structural alteration occurs. On the other hand, the Y chromosome genome is basically a region transmitted only from father to son, reflecting a male-specific inheritance between generations. The Y chromosome exhibits genomic structural differences among different ethnic groups and individuals. The Y chromosome was previously thought to affect only male-specific phenotypes, but recent studies have revealed associations between the Y chromosomes and phenotypes common to both males and females, such as certain types of cancer and neuropsychiatric disorders. This evidence was discovered with the finding of the mosaic loss of the Y chromosome in somatic cells. This phenomenon is also affected by environmental factors, such as smoking and aging. In the past, functional analysis of the Y chromosome has been elucidated by assessing the function of Y chromosome-specific genes and the association between Y chromosome haplogroups and human phenotypes. These studies are currently being conducted intensively. Additionally, the recent advance of large-scale genome cohort studies has increased the amount of Y chromosome genomic information available for analysis, making it possible to conduct more precise studies of the relationship between genome structures and phenotypes. In this review, we will introduce recent analyses using large-scale genome cohort data and previously reported association studies between Y chromosome haplogroups and human phenotypes, such as male infertility, cancer, cardiovascular system traits, and neuropsychiatric disorders. The function and biological role of the Y chromosome in human phenotypes will also be discussed.

A review of studies examining the association between genetic biomarkers (short tandem repeats and single-nucleotide polymorphisms) and risk of prostate cancer: the need for valid predictive biomarkers

Prostate cancer (PCa) is a challenging polygenic disease because the genes that cause PCa remain largely elusive and are affected by several causal factors. Consequently, research continuously strives to identify a genetic marker which could be used as an indicator to predict the most vulnerable (i.e., predisposed) segments of the population to the disease or for the gene which may be directly responsible for PCa. To enhance the genetic etiology of PCa, this research sought to discover the key studies conducted in this field using data from the main journal publication search engines, as it was hoped that this could shed light on the main research findings from these studies, which in turn could assist in determining these genes or markers. From the research highlighted, the studies primarily used two kinds of markers: short tandem repeats or single-nucleotide polymorphisms. These markers were found to be quite prevalent in all the chromosomes within the research carried out. It also became apparent that the studies differed in both quantity and quality, as well as being conducted in a variety of societies. Links were also determined between the degree and strength of the relationship between these markers and the occurrence of the disease. From the studies identified, most recommended a larger and more diverse survey for the parameters which had not been studied before, as well as an increase in the size of the community (i.e., the population) being studied. This is an indication that work in this field is far from complete, and thus, current research remains committed toward finding genetic markers that can be used clinically for the diagnosis and screening of patients with PCa.

Contribution of MSMB promoter region gene polymorphism to early-onset prostate cancer risk in Mexican males

Sexually transmitted infections and its contribution to prostate cancer (PC) development have been relevant in different populations. MSMB gene polymorphism (rs10993994) has exhibited an association both with PC as well as the susceptibility to sexually transmitted infections. Hitherto, these conditions have been not studied in Mexico yet, neither if sexually transmitted infections could modify the MSMB and PC association. Herein, socio-demographic features, sexually transmitted infections records, the reproductive backgrounds, and the genetic characterisation were analysed in 322 incident PC cases and 628 population healthy controls from Mexico City. Whole PC, early-onset PC (PC at < 60 years old), late-onset PC (≥ 60 years old), and PC aggressiveness were used to evaluate the genetic variants contribution to PC risk using unconditional logistic regression models. Overall, none associations between the allelic variants of rs10993994 polymorphisms with whole and PC aggressiveness were found. Howbeit, the TT genotype carriers presented the highest susceptibility to develop early-onset PC (OR = 2.66; 95% CI = 1.41, 5.04; p = 0.03) than CC+CT carriers, both with codominant and recessive models. Although none association between whole PC and MSMB gene polymorphism was found, our results were reinforced by prior studies in European descendent populations, suggesting a contribution between rs10993994 and early-onset PC development.

The incidence, mortality, and risk factors of prostate cancer in Asian men

The objective of this review was to describe the epidemiology and risk factors of prostate cancer (PCa) in Asian populations. English language publications published over the last 10 years covering studies on the incidence, mortality, and risk factors of PCa in Asia were reviewed. The incidence of PCa in Asia is rising but is still significantly lower than that in Western countries. Studies in Asia indicated that the consumption of red meat, fat, dairy, and eggs was associated with a higher risk for PCa. Age and family history were also found to be risk factors. The emergence of genetic data indicates that different genetic backgrounds between Asian and Western populations play a role in the observed differences in PCa incidence. The lower incidence of PCa in Asian men than in Western men may in part be due to a lack of systematic prostate-specific antigen screening, but environmental and genetic factors also play a role.

Prostate cancer susceptibility and growth linked to Y chromosome genes

The role of Y chromosome in prostate cancer progression and incidence is not well known. Among the 46 chromosomes, Y chromosome determines the male gender. The Y chromosome is smaller than the X chromosome and contains only 458 genes compared to over 2000 genes found in the X chromosome. The Y chromosome is prone to high mutation rates, created exclusively in sperm cells due to the highly oxidative environment of the testis. Y chromosome harbors epigenetic information, which affects the expression of genes associated with the incidence and progression of prostate cancer. In this review, we focus on Y chromosome related genetic abnormalities, likely to be involved in the development and progression of prostate cancer.

Chromosome Y genetic variants: impact in animal models and on human disease

Chromosome Y (chrY) variation has been associated with many complex diseases ranging from cancer to cardiovascular disorders. Functional roles of chrY genes outside of testes are suggested by the fact that they are broadly expressed in many other tissues and correspond to regulators of basic cellular functions (such as transcription, translation, and protein stability). However, the unique genetic properties of chrY (including the lack of meiotic crossover and the presence of numerous highly repetitive sequences) have made the identification of causal variants very difficult. Despite the prior lack of reliable sequences and/or data on genetic polymorphisms, earlier studies with animal chrY consomic strains have made it possible to narrow down the phenotypic contributions of chrY. Some of the evidence so far indicates that chrY gene variants associate with regulatory changes in the expression of other autosomal genes, in part via epigenetic effects. In humans, a limited number of studies have shown associations between chrY haplotypes and disease traits. However, recent sequencing efforts have made it possible to greatly increase the identification of genetic variants on chrY, which promises that future association of chrY with disease traits will be further refined. Continuing studies (both in humans and in animal models) will be critical to help explain the many sex-biased disease states in human that are contributed to not only by the classical sex steroid hormones, but also by chrY genetics.

Y chromosome haplogroup D2a1 is significantly associated with high levels of luteinizing hormone in Japanese men

The association between the Y chromosome haplogroup D2 and risk of azoospermia and low sperm motility has been previously studied, and it was indicated that haplogroups DE (YAP lineage) are associated with prostate cancer risk in Japanese males. Our assumption had been that Y chromosome haplogroups may be associated with sex hormone levels, because sex hormones have been deemed responsible for spermatogenesis and carcinogenesis. In this study, we assessed the association between Y chromosome haplogroups and sex hormone levels, including those of testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), luteinizing hormone (LH), inhibin-B, and calculated free testosterone (cFT), in 901 young men from the general Japanese population (cohort 1) and 786 Japanese men of proven fertility (cohort 2). We found that the haplogroup D2a1 was significantly associated with high LH levels in a combined analysis involving two cohorts (β = 0.068, SE = 0.025, p = 0.0075), following correction for multiple testing. To date, this result is the first evidence that implicates Y chromosome haplogroups in an association with sex hormone levels.

Identification of specific Y chromosomes associated with increased prostate cancer risk

BACKGROUND

Evidence supports the possibility of a role of the Y chromosome in prostate cancer, but controversy exists.

METHODS

A novel analysis of a computerized population-based resource linking genealogy and cancer data was used to test the hypothesis of a role of the Y chromosome in prostate cancer predisposition. Using a statewide cancer registry from 1966 linked to a computerized genealogy representing over 1.2 million descendants of the Utah pioneers, 1,000 independent sets of males, each set hypothesized to share the same Y chromosome as represented in genealogy data, were tested for a significant excess of prostate cancer.

RESULTS

Multiple Y chromosomes representing thousands of potentially at-risk males were identified to have a significant excess risk for prostate cancer.

CONCLUSIONS

This powerful and efficient in silico test of an uncommon mode of inheritance has confirmed evidence for Y chromosome involvement in prostate cancer.

Novel effects of chromosome Y on cardiac regulation, chromatin remodeling, and neonatal programming in male mice

Little is known about the functions of chromosome Y (chrY) genes beyond their effects on sex and reproduction. In hearts, postpubertal testosterone affects the size of cells and the expression of genes differently in male C57BL/6J than in their C57.Y(A) counterparts, where the original chrY has been substituted with that from A/J mice. We further compared the 2 strains to better understand how chrY polymorphisms may affect cardiac properties, the latter being sexually dimorphic but unrelated to sex and reproduction. Genomic regions showing occupancy with androgen receptors (ARs) were identified in adult male hearts from both strains by chromatin immunoprecipitation. AR chromatin immunoprecipitation peaks (showing significant enrichment for consensus AR binding sites) were mostly strain specific. Measurements of anogenital distances in male pups showed that the biologic effects of perinatal androgens were greater in C57BL/6J than in C57.Y(A). Although perinatal endocrine manipulations showed that these differences contributed to the strain-specific differences in the response of adult cardiac cells to testosterone, the amounts of androgens produced by fetal testes were not different in each strain. Nonetheless, chrY polymorphisms associated in newborn pups' hearts with strain-specific differences in genomic regions showing either AR occupancy, accessible chromatin sites, or trimethylation of histone H3 Lysine 4 marks, as well as with differential expression of 2 chrY-encoded histone demethylases. In conclusion, the effects of chrY on adult cardiac phenotypes appeared to result from an interaction of this chromosome with the organizational programming effects exerted by the neonatal testosterone surge and show several characteristics of being mediated by an epigenetic remodeling of chromatin.

Fate of the human Y chromosome linked genes and loci in prostate cancer cell lines DU145 and LNCaP

Background

Prostate cancer is a known cause of mortality in men worldwide although the risk factor varies among different ethnic groups. Loss of the Y chromosome is a common chromosomal abnormality observed in the human prostate cancer.

Results

We screened 51 standard sequence tagged sites (STSs) corresponding to a male-specific region of the Y chromosome (MSY), sequenced the coding region of the SRY gene and assessed the status of the DYZ1 arrays in the human prostate cancer cell lines DU145 and LNCaP. The MSY was found to be intact and coding region of SRY showed no sequence variation in both the cell lines. However, DYZ1 arrays showed sequence and copy number variations. DU145 and LNCaP cells were found to carry 742 and 1945 copies of the DYZ1, respectively per 3.3 pg of genomic DNA. The DYZ1 copies detected in these cell lines are much below the average of that reported in normal human males. Similarly, the number of “TTCCA” repeat and its derivatives within the DYZ1 arrays showed variation compared to those of the normal males.

Conclusions

Clearly, the DYZ1 is maximally affected in both the cell lines. Work on additional cell lines and biopsied samples would augment our understanding about the susceptibility of this region. Based on the present work, we construe that copy number status of the DYZ1 may be exploited as a supplementary prognostic tool to monitor the occurrence of prostate cancer using biopsied samples.

Chromosome Y variants from different inbred mouse strains are linked to differences in the morphologic and molecular responses of cardiac cells to postpubertal testosterone

BACKGROUND

We have reported previously that when chromosome Y (chrY) from the mouse strain C57BL/6J (ChrYC57) was substituted for that of A/J mice (ChrYA), cardiomyocytes from the resulting "chromosome substitution" C57BL/6J-chrYA strain were smaller than that of their C57BL/6J counterparts. In reverse, when chrYA from A/J mice was substituted for that of chrYC57, cardiomyocytes from the resulting A/J-chrYC57 strain were larger than in their A/J counterparts. We further used these strains to test whether: 1) the origin of chrY could also be linked to differences in the profile of gene expression in the hearts of adult male mice, and 2) post-pubertal testosterone could play a role in the differential morphologic and/or molecular effects of chrYC57 and chrYA.

RESULTS

The increased size of cardiomyocytes from adult male C57BL/6J mice compared to C57BL/6J-chrYA resulted from the absence of hypertrophic effects of post-pubertal testosterone on cells from the latter strain. However, gene profiling revealed that the latter effect could not be explained on the basis of an insensitivity of cells from C57BL/6J-chrYA to androgens, since even more cardiac genes were affected by post-pubertal testosterone in C57BL/6J-chrYA hearts than in C57BL/6J. By testing for interaction between the effects of surgery and strain, we identified 249 "interaction genes" whose expression was affected by post-pubertal testosterone differentially according to the genetic origin of chrY. These interaction genes were found to be enriched within a limited number of signaling pathways, including: 1) p53 signaling, which comprises the interacting genes Ccnd1, Pten and Cdkn1a that are also potential co-regulators of the androgen receptors, and 2) circadian rhythm, which comprises Arntl/Bmal1, which may in turn regulate cell growth via the control of Cdkn1a.

CONCLUSION

Although post-pubertal testosterone increased the size of cardiomyocytes from male C56BL/6J mice but not that from their C57BL/6J-chrYA counterparts, it affected gene expression in the hearts from both strains. However, several cardiac genes responded to post-pubertal testosterone in a strict strain-selective manner, which provides possible mechanisms explaining how chrY may, in part via interference with androgen regulatory events, be linked to morphologic differences of cardiac cells of adult male mice.

Prognostic factors in patients with acute liver failure undergoing live donor liver transplantation

Mortality from acute liver failure (ALF) is high. Live donor liver transplantation (LDLT) is the treatment of choice for ALF in Asia, because cadaveric donors are rare. We sought to review our results in ALF patients with undergoing LDLT at our center. One hundred two LDLTs were performed at our center from April 2002 to November 2007, 15 (14%) because of ALF. Mean (SEM; median, range) follow-up was 1,065 (189; 1400; 3-2046) days. Nine patients (60%) had acute exacerbation of chronic hepatitis B; and 6 (40%) had drug-induced liver injury. Age was 47 (3; 50; 27-65) years. Ten patients (67%) were men. At transplantation, laboratory values were included bilirubin, 449 (35) micromol/L; creatinine concentration, 182 (32) mmol/L. The international normalized ratio was 2.4 (0.2). The Model for End-Stage Liver Disease (MELD) score was 34 (2). Both inpatient and long-term mortality was 20% 3 of 15 patients died. The 5-year survival was 80%. Compared with survivors, patients who died had a significantly higher creatinine concentration 289 vs 155 micromol/L, international normalized ratio (3.4 vs 2.1), MELD score (47 vs 32). We conclude that despite being sick with median and mean MELD scores of 32 and 34, 80% of patients with ALF can achieve good long-term survival after LDLT.

Lack of association between Y-chromosomal haplogroups and prostate cancer in the Korean population

The Y chromosome has recently been suggested to have an association with prostate cancer risk in human populations. Since this chromosome is haploid and lacks recombination over most of its length, haplotypes constructed from binary markers throughout the chromosome can be used for association studies. To assess the possible Y-chromosomal contribution to prostate cancer risk, we have therefore analyzed 14 Y-chromosomal binary markers in 106 prostate cancer cases and 110 controls from the Korean population. In contrast to previous findings in the Japanese population, no statistically significant difference in the distribution of Y-chromosomal haplogroup frequencies was observed between the case and control groups of Koreans. Thus, our data imply that the previously reported associations between Y-chromosomal lineages and a predisposition to, or protection against, prostate cancer might be explained by statistical fluctuations, or by genetic effects that are seen only in some environments.