European genome-wide association study identifies SLC14A1 as a new urinary bladder cancer susceptibility gene

Distinct SNP combinations confer susceptibility to urinary bladder cancer in smokers and non-smokers

Recently, genome-wide association studies have identified and validated genetic variations associated with urinary bladder cancer (UBC). However, it is still unknown whether the high-risk alleles of several SNPs interact with one another, leading to an even higher disease risk. Additionally, there is no information available on how the UBC risk due to these SNPs compare to the risk of cigarette smoking and to occupational exposure to urinary bladder carcinogens, and whether the same or different SNP combinations are relevant in smokers and non-smokers. To address these questions, we analyzed the genotypes of six SNPs, previously found to be associated with UBC, together with the GSTM1 deletion, in 1,595 UBC cases and 1,760 controls, stratified for smoking habits. We identified the strongest interactions of different orders and tested the stability of their effect by bootstrapping. We found that different SNP combinations were relevant in smokers and non-smokers. In smokers, polymorphisms involved in detoxification of cigarette smoke carcinogens were most relevant (GSTM1, rs11892031), in contrast to those in non-smokers with MYC and APOBEC3A near polymorphisms (rs9642880, rs1014971) being the most influential. Stable combinations of up to three high-risk alleles resulted in higher odds ratios (OR) than the individual SNPs, although the interaction effect was less than additive. The highest stable combination effects resulted in an OR of about 2.0, which is still lower than the ORs of cigarette smoking (here, current smokers' OR: 3.28) and comparable to occupational carcinogen exposure risks which, depending on the workplace, show mostly ORs up to 2.0.

Identification of androgen-regulated genes in human prostate

Androgens are essential for the development of the prostate and prostate cancer. We examined androgen-regulated gene expression in the human prostate. Samples from benign and malignant prostate tissue and samples containing prostate tissue obtained from prostate cancer patients three days after surgical castration were further processed as probes for a GeneChip array. The comparison of gene expression profiles in castrated samples and in benign or malignant prostate tissue samples revealed androgen-regulated genes. We further evaluated the genes which were differentially expressed in benign and malignant prostate samples. The androgen-regulated expression of dual specificity phosphatase 1 (DUSP1) was confirmed in the LNCaP prostate cancer cell line, as the expression of DUSP1 increased with androgen treatment over the course of time. The expression of the genes CRISP3, PCA3, OR51E2, HOXC6, AGR3, AMACR and SLC14A1 was affected by castration in addition to differential expression in the benign and malignant prostate. These sample results require further investigation for the role of AGR3 and SLC14A1 in prostate cancer as these associations have not been reported previously.

Epidemiology and risk factors of urothelial bladder cancer

CONTEXT

Urothelial bladder cancer (UBC) is a disease of significant morbidity and mortality. It is important to understand the risk factors of this disease.

OBJECTIVE

To describe the incidence, prevalence, and mortality of UBC and to review and interpret the current evidence on and impact of the related risk factors.

EVIDENCE ACQUISITION

A literature search in English was performed using PubMed. Relevant papers on the epidemiology of UBC were selected.

EVIDENCE SYNTHESIS

UBC is the 7th most common cancer worldwide in men and the 17th most common cancer worldwide in women. Approximately 75% of newly diagnosed UBCs are noninvasive. Each year, approximately 110 500 men and 70 000 women are diagnosed with new cases and 38 200 patients in the European Union and 17 000 US patients die from UBC. Smoking is the most common risk factor and accounts for approximately half of all UBCs. Occupational exposure to aromatic amines and polycyclic aromatic hydrocarbons are other important risk factors. The impact of diet and environmental pollution is less evident. Increasing evidence suggests a significant influence of genetic predisposition on incidence.

CONCLUSIONS

UBC is a frequently occurring malignancy with a significant impact on public health and will remain so because of the high prevalence of smoking. The importance of primary prevention must be stressed, and smoking cessation programs need to be encouraged and supported.

Structure and permeation mechanism of a mammalian urea transporter

As an adaptation to infrequent access to water, terrestrial mammals produce urine that is hyperosmotic to plasma. To prevent osmotic diuresis by the large quantity of urea generated by protein catabolism, the kidney epithelia contain facilitative urea transporters (UTs) that allow rapid equilibration between the urinary space and the hyperosmotic interstitium. Here we report the first X-ray crystal structure of a mammalian UT, UT-B, at a resolution of 2.36 Å. UT-B is a homotrimer and each protomer contains a urea conduction pore with a narrow selectivity filter. Structural analyses and molecular dynamics simulations showed that the selectivity filter has two urea binding sites separated by an approximately 5.0 kcal/mol energy barrier. Functional studies showed that the rate of urea conduction in UT-B is increased by hypoosmotic stress, and that the site of osmoregulation coincides with the location of the energy barrier.

Urea transporter physiology studied in knockout mice

In mammals, there are two types of urea transporters; urea transporter (UT)-A and UT-B. The UT-A transporters are mainly expressed in kidney epithelial cells while UT-B demonstrates a broader distribution in kidney, heart, brain, testis, urinary tract, and other tissues. Over the past few years, multiple urea transporter knockout mouse models have been generated enabling us to explore the physiological roles of the different urea transporters. In the kidney, deletion of UT-A1/UT-A3 results in polyuria and a severe urine concentrating defect, indicating that intrarenal recycling of urea plays a crucial role in the overall capacity to concentrate urine. Since UT-B has a wide tissue distribution, multiple phenotypic abnormalities have been found in UT-B null mice, such as defective urine concentration, exacerbated heart blockage with aging, depression-like behavior, and earlier male sexual maturation. This review summarizes the new insights of urea transporter functions in different organs, gleaned from studies of urea transporter knockout mice, and explores some of the potential pharmacological prospects of urea transporters.

Association of lung adenocarcinoma clinical stage with gene expression pattern in noninvolved lung tissue

Associations between clinical outcome of cancer patients and the gene expression signature in primary tumors at time of diagnosis have been reported. To test whether gene expression patterns in noninvolved lung tissue might correlate with clinical stage in lung adenocarcinoma (ADCA) patients, we compared the transcriptome of noninvolved lung samples from 60 ADCA smoker patients of clinical stage I versus 60 patients with stage>I. Quantitative PCR of 10 genes with the most significant differential expression confirmed the statistical association with clinical stage in eight genes, six of which were downregulated in high-stage patients. Five of these six genes were also downregulated in lung ADCA tissue as compared to noninvolved tissue. Studies in vitro indicated that four of the genes (SLC14A1, SMAD6, TMEM100 and TXNIP) inhibited colony formation of lung cancer cell lines transfected to overexpress the genes, suggesting their potential tumor-suppressor activity. Our findings suggest that individual variations in the transcriptional profile of noninvolved lung tissue may reflect the lung ADCA patient's predisposition to tumor aggressiveness.

Bladder cancer survival in a former industrial area in Saxony-Anhalt, Germany

Long-term follow-ups on bladder cancer patients from highly industrialized areas are rare. Therefore, we present a follow-up of bladder cancer patients from the greater area Lutherstadt Wittenberg, a center of the chemical industry of the former German Democratic Republic. Relapse-free survival times of 213 confirmed bladder cancer cases from the greater area Lutherstadt Wittenberg were collected between 2008 and 2009. Data on lifestyle and occupational exposure to potential carcinogens was recorded by questionnaire. Genotypes of N-acetyltransferase 2 (NAT2), glutathione S-transferase M1 (GSTM1), glutathione S-transferase T1 (GSTT1), rs710521, and rs9642880 were determined by standard methods. Cox models were used to evaluate differences in relapse-free survival. Clear differences in relapse-free survival could be observed for the number of relapses, multilocular tumor growth, and relapses with higher staging or grading than the primary tumor, as well as GSTT1. None of the other investigated polymorphisms showed significant impact on prognosis. This is the first study on two recently detected single-nucleotide polymorphisms (SNPs) showing that these polymorphisms may also contribute to shorter relapse-free times.