Search for genetic factor association with cancer-free prostate-specific antigen level elevation on the basis of a genome-wide association study in the Korean population

We investigated the genetic markers associated with elevated serum prostate-specific antigen (sPSA) levels to improve the predictive power of sPSA in screening for prostate cancer. A genome-wide association study was carried out among 4124 healthy Korean male adults using the Affymetrix Axiom Customized Biobank Genotyping Arrays for sPSA levels. A subgroup analysis for increased sPSA levels who underwent a prostate biopsy (n=64) was also carried out. We detected 11 single nucleotide polymorphisms (SNPs) near the Solute carrier family 45member 3, AGAP7P, MSMB, LOC101929917, and KLK3 genes associated with sPSA levels. The top SNP associated with the log of the sPSA levels was rs72434280 in the Solute carrier family 45 member 3 gene (P value, discovery set=2.98×10, replication set=7.31×10). A case-control study utilizing available biopsy reports (49 patients with normal biopsies vs. 15 patients with biopsies indicating cancer) for the sPSA more than 3 ng/ml group was carried out for the respective SNPs after adjusting for age. Only the SNPs near the KLK3 gene were associated with prostate cancer. In the model of the predictive elevation of sPSA level, adding the genetic risk score [area under the curve (AUC)=0.697] to age and BMI (AUC=0.602) significantly improved the results of the AUC (P<0.0001). We found seven SNPs associated with elevated prostate-specific antigen levels in healthy Korean men. Four SNPs were a novel marker in the Korean population. In men with increased prostate-specific antigen levels, genotyping SNP related to cancer-free elevation of sPSA level could be informative to decide the indication of prostate biopsy.

Involvement of Kallikrein-Related Peptidases in Normal and Pathologic Processes

Human kallikrein-related peptidases (KLKs) are a subgroup of serine proteases that participate in proteolytic pathways and control protein levels in normal physiology as well as in several pathological conditions. Their complex network of stimulatory and inhibitory interactions may induce inflammatory and immune responses and contribute to the neoplastic phenotype through the regulation of several cellular processes, such as proliferation, survival, migration, and invasion. This family of proteases, which includes one of the most useful cancer biomarkers, kallikrein-related peptidase 3 or PSA, also has a protective effect against cancer promoting apoptosis or counteracting angiogenesis and cell proliferation. Therefore, they represent attractive therapeutic targets and may have important applications in clinical oncology. Despite being intensively studied, many gaps in our knowledge on several molecular aspects of KLK functions still exist. This review aims to summarize recent data on their involvement in different processes related to health and disease, in particular those directly or indirectly linked to the neoplastic process.

Associations of prostate cancer risk variants with disease aggressiveness: results of the NCI-SPORE Genetics Working Group analysis of 18,343 cases

Genetic studies have identified single nucleotide polymorphisms (SNPs) associated with the risk of prostate cancer (PC). It remains unclear whether such genetic variants are associated with disease aggressiveness. The NCI-SPORE Genetics Working Group retrospectively collected clinicopathologic information and genotype data for 36 SNPs which at the time had been validated to be associated with PC risk from 25,674 cases with PC. Cases were grouped according to race, Gleason score (Gleason ≤ 6, 7, ≥ 8) and aggressiveness (non-aggressive, intermediate, and aggressive disease). Statistical analyses were used to compare the frequency of the SNPs between different disease cohorts. After adjusting for multiple testing, only PC-risk SNP rs2735839 (G) was significantly and inversely associated with aggressive (OR = 0.77; 95 % CI 0.69-0.87) and high-grade disease (OR = 0.77; 95 % CI 0.68-0.86) in European men. Similar associations with aggressive (OR = 0.72; 95 % CI 0.58-0.89) and high-grade disease (OR = 0.69; 95 % CI 0.54-0.87) were documented in African-American subjects. The G allele of rs2735839 was associated with disease aggressiveness even at low PSA levels (<4.0 ng/mL) in both European and African-American men. Our results provide further support that a PC-risk SNP rs2735839 near the KLK3 gene on chromosome 19q13 may be associated with aggressive and high-grade PC. Future prospectively designed, case-case GWAS are needed to identify additional SNPs associated with PC aggressiveness.

Susceptibility loci associations with prostate cancer risk in northern Chinese men

BACKGROUND

KLK3 gene products, like human prostate-specific antigen (PSA), are important biomarkers in the clinical diagnosis of prostate cancer (PCa). G protein-coupled receptor RFX6, C2orf43 and FOXP4 signaling plays important roles in the development of PCa. However, associations of these genes with PCa in northern Chinese men remain to be detailed. This study aimed to investigate their impact on occurrence and level of malignancy.

METHODS

All subjects were from Beijing and Tianjin, including 266 cases with prostate cancer and 288 normal individuals as controls. We evaluated associations between clinical covariates (age at diagnosis, prostate specific antigen, Gleason score, tumor stage and aggressive) and 6 candidate PCa risk loci, genotyped by PCR- high resolution melting curve and sequencing methods.

RESULTS

Case-control analysis of allelic frequency of PCa associated with PCa showed that one of the 6 candidate risk loci, rs339331 in the RFX6 gene, was associated with reduced risk of prostate cancer (odds ratio (OR) = 0.73, 95% confidence interval (CI) =0.57-0.94, P = 0.013) in northern Chinese men. In addition, subjects with CX (CC+TC) genotypes had a decreased risk for prostrate cancer compared to those carrying the TT homozygote (OR =0.64, 95% CI = 0.45- 0.90, P = 0.008). The TT genotype of 13q22 (rs9600079, T) was associated with tumor stage (P=0.044, OR=2.34, 95% CI=0.94-5.87). Other SNPs were not significantly associated with clinical covariates in prostate cancer (P > 0.05). CONCLUSIONS. rs339331 in the RFX6 gene may be associated with prostate cancer as a susceptibility locus in northern Chinese men.

Pathway analysis of genome-wide association study on serum prostate-specific antigen levels

The wide application of prostate-specific antigen (PSA) has contributed to the early diagnosis and improved management of prostate cancer (PCa). Accumulating evidence has suggested the involvement of genetic components in regulating serum PSA levels, and several single nucleotide polymorphisms (SNPs) have been identified by genome-wide association studies (GWASs). However, the GWASs' results have the limited power to identify the causal variants and pathways. After the quality control filters, a total of 330,540 genotyped SNPs from one GWAS with 657 PCa-free Caucasian males were included for the identify candidate causal SNPs and pathways (ICSNPathway) analysis. In addition, the genotype-phenotype association analysis has been conducted with the data from HapMap database. Overall, a total of four SNPs in three genes and six pathways were identified by ICSNPathway analysis, which in total provided three hypothetical mechanisms. First, CYP26B1 rs2241057 polymorphism (nonsynonymous coding) which leads to a Leu-to-Ser amino acid shift at position 264, was implicated in the pathways including meiosis, proximal/distal pattern formation, and M phase of meiotic cell cycle. Second, CLIC5 rs3734207 and rs11752816 polymorphisms (regulatory region) to the 2 iron, 2 sulfur cluster binding pathway through regulating expression levels of CLIC5 mRNA. Third, rs4819522 polymorphism (nonsynonymous coding) leads to a Thr-to-Met transition at position 350 of TBX1 and involves in the pathways about gland and endocrine system development. In summary, our results demonstrated four candidate SNPs in three genes (CYP26B1 rs2241057, CISD1 rs2251039, rs2590370, and TBX1 rs4819522 polymorphisms), which were involved in six potential pathways to influence serum PSA levels.