Genome-wide association study yields variants at 20p12.2 that associate with urinary bladder cancer.

Genome-wide association studies (GWAS) of urinary bladder cancer (UBC) have yielded common variants at 12 loci that associate with risk of the disease. We report here the results of a GWAS of UBC including 1670 UBC cases and 90 180 controls, followed by replication analysis in additional 5266 UBC cases and 10 456 controls. We tested a dataset containing 34.2 million variants, generated by imputation based on whole-genome sequencing of 2230 Icelanders. Several correlated variants at 20p12, represented by rs62185668, show genome-wide significant association with UBC after combining discovery and replication results (OR = 1.19, P = 1.5 × 10(-11) for rs62185668-A, minor allele frequency = 23.6%). The variants are located in a non-coding region approximately 300 kb upstream from the JAG1 gene, an important component of the Notch signaling pathways that may be oncogenic or tumor suppressive in several forms of cancer. Our results add to the growing number of UBC risk variants discovered through GWAS.

In vitro functional effects of XPC gene rare variants from bladder cancer patients.

The XPC gene is involved in repair of bulky DNA adducts formed by carcinogenic metabolites and oxidative DNA damage, both known bladder cancer risk factors. Single nucleotide polymorphisms (SNPs) in XPC have been associated with increased bladder cancer risk. Recently, rarer genetic variants have been identified but it is difficult to ascertain which are of functional importance. During a mutation screen of XPC in DNA from 33 bladder tumour samples and matched blood samples, we identified five novel variants in the patients' germ line DNA. In a case-control study of 771 bladder cancer cases and 800 controls, c.905T>C (Phe302Ser), c.1177C>T (Arg393Trp), c.*156G>A [3' untranslated region (UTR)] and c.2251-37C>A (in an intronic C>G SNP site) were found to be rare variants, with a combined odds ratio of 3.1 (95% confidence interval 1.0-9.8, P=0.048) for carriage of one variant. The fifth variant was a 2% minor allele frequency SNP not associated with bladder cancer. The two non-synonymous coding variants were predicted to have functional effects using analytical algorithms; a reduced recruitment of GFP-tagged XPC plasmids containing either c.905T>C or c.1177C>T to sites of 408 nm wavelength laser-induced oxidative DNA damage was found in vitro. c.*156G>A appeared to be associated with reduced messenger RNA stability in an in vitro plasmid-based assay. Although the laser microbeam assay is relevant to a range of DNA repair genes, our 3' UTR assay based on Green fluorescent protein(GFP) has widespread applicability and could be used to assess any gene. These assays may be useful in determining which rare variants are functional, prior to large genotyping efforts.

Papillary and muscle invasive bladder tumors with distinct genomic stability profiles have different DNA repair fidelity and KU DNA-binding activities.

Low-grade noninvasive papillary bladder tumors are genetically stable whereas muscle invasive bladder tumors display high levels of chromosomal aberrations. As cells deficient for nonhomologous end-joining (NHEJ) pathway components display increased genomic instability, we sought to determine the NHEJ repair characteristics of bladder tumors and correlate this with tumor stage and grade. A panel of 13 human bladder tumors of defined stage and grade were investigated for chromosomal aberrations by comparative genomic hybridization and for NHEJ repair fidelity and function. Repair assays were conducted with extracts made directly from bladder tumor specimens to avoid culture-induced phenotypic alterations and selection bias as only a minority of bladder tumors grow in culture. Four noninvasive bladder tumors (pTaG2), which were genetically stable, repaired a partially incompatible double-strand break (DSB) by NHEJ-dependent annealing of termini and fill-in of overhangs with minimal loss of nucleotides. In contrast, four muscle invasive bladder cancers (pT2-3G3), which displayed gross chromosomal rearrangements, repaired DSBs in an error-prone manner involving extensive resection and microhomology association. Four minimally invasive bladder cancers (pT1G3) had characteristics of both repair types. Error-prone repair in bladder tumors correlated with reduced KU DNA-binding and loss of TP53 function. In conclusion, there were distinct differences in DSB repair between noninvasive papillary tumors and higher stage/grade invasive cancers. End-joining fidelity correlated with stage and was increasingly error-prone as tumors became more invasive and KU binding activity reduced; these changes may underlie the different genomic profiles of these tumors.

APE1 and XRCC1 protein expression levels predict cancer-specific survival following radical radiotherapy in bladder cancer.

INTRODUCTION: Radiotherapy offers the potential of bladder preservation in muscle-invasive bladder cancer, but only a proportion of tumors respond, and there are no accurate predictive methods. The ability of tumor cells to repair DNA damage induced by ionizing radiation influences radiosensitivity. We therefore investigated the prognostic value of the DNA repair proteins APE1 and XRCC1 in patients with muscle-invasive bladder cancer treated by radical radiotherapy. MATERIALS AND METHODS: The tumors of 90 patients with muscle-invasive transitional cell carcinoma and known clinical outcomes were immunostained with APE1 and XRCC1 antibodies. Levels of protein expression were assessed as a percentage of tumor cells with positive nuclear staining (1,000 cells per tumor). RESULTS: The median percentage of nuclear staining for APE1 was 98.7% (range, 42.2-100%) and for XRCC1 was 96.5% (range, 0.6-99.6%). High expression levels of APE1 or XRCC1 (> or = 95% positivity) were associated with improved patient cancer-specific survival (log-rank, P = 0.02 and 0.006, respectively). In a multivariate Cox regression model, APE1 and XRCC1 expression and hydronephrosis were the only independent predictors of patient survival. CONCLUSIONS: Expression levels of both APE1 and XRCC1 proteins were strongly associated with patient outcome following radiotherapy, separating patients with good outcome from the 50% with poor outcome (82% and 44%, 3-year cause-specific survival, respectively). If prospectively validated, this simple test could be incorporated into clinical practice to select patients likely to respond to radiotherapy and consider alternative forms of therapy for those unlikely to respond.

The prevalence of newly diagnosed hyperlipidaemia in men with erectile dysfunction.

OBJECTIVE: To determine the prevalence of newly diagnosed hypercholesterolaemia and hypertriglyceridaemia in patients presenting to an andrology clinic with erectile dysfunction (ED), and to assess the relationship between serum lipid levels and the severity of ED. PATIENTS AND METHODS: In all, 199 consecutive men attending an ED clinic were assessed for risk factors for ED; patients completed the International Index of Erectile Function (IIEF)-15 questionnaire and provided venous blood samples for assaying fasting total cholesterol and total triglyceride levels. The proportion of newly diagnosed hyperlipidaemia in patients presenting with ED was calculated and related to patient age, total IIEF score and severity of ED. RESULTS: Using a threshold of 5.0 mmol/L, there was newly diagnosed hypercholesterolaemia in 40% of the men, while there was undiagnosed hypertriglyceridaemia (>2 mmol/L) in 29% of the population. There was no clear correlation between patient age and the fasting lipid levels, and no association between total IIEF-15 score or severity of ED and serum cholesterol and triglyceride levels. CONCLUSION: This study shows the high prevalence of undiagnosed hypercholesterolaemia and hypertriglyceridaemia in men presenting with ED. The opportunity to screen for and treat these risk factors has long-term benefits in preventing cardiovascular disease in this group of patients.