Cigarette smoking, von Hippel-Lindau gene mutations and sporadic renal cell carcinoma

Coffee intake and trace element blood concentrations in association with renal cell cancer among smokers

PURPOSE

To determine whether higher coffee intake may reduce the risk of renal cell cancer (RCC) associated with lead (Pb) and other heavy metals with known renal toxicity.

METHODS

We conducted a nested case-control study of male smokers (136 RCC cases and 304 controls) within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Cases diagnosed with RCC at 5 or more years following cohort enrollment were matched to controls on age (± 7 years) and whole blood draw date (± 30 days). Conditional logistic regression (using two-sided tests) was used to test for main effects and additive models of effect modification.

RESULTS

After a mean follow-up of 16.3 years, coffee consumption was not significantly associated with renal cell cancer risk, when adjusting for blood concentrations of Cd, Hg, and Pb and RCC risk factors (age, smoking, BMI, and systolic blood pressure) (p-trend, 0.134). The association with above median blood Pb and RCC (HR = 1.69, 95% CI 1.06, 2.85) appeared to be modified by coffee consumption, such that RCC risk among individuals with both increased coffee intake and higher blood lead concentration were more than threefold higher RCC risk (HR = 3.40, 95% CI 1.62, 7.13; p-trend, 0.003).

CONCLUSION

Contrary to our initial hypothesis, this study suggests that heavy coffee consumption may increase the previously identified association between higher circulating lead (Pb) concentrations and increased RCC risk. Improved assessment of exposure, including potential trace element contaminants in coffee, is needed.

Genomic investigation of etiologic heterogeneity: methodologic challenges

Background

The etiologic heterogeneity of cancer has traditionally been investigated by comparing risk factor frequencies within candidate sub-types, defined for example by histology or by distinct tumor markers of interest. Increasingly tumors are being profiled for molecular features much more extensively. This greatly expands the opportunities for defining distinct sub-types. In this article we describe an exploratory analysis of the etiologic heterogeneity of clear cell kidney cancer. Data are available on the primary known risk factors for kidney cancer, while the tumors are characterized on a genome-wide basis using expression, methylation, copy number and mutational profiles.

Methods

We use a novel clustering strategy to identify sub-types. This is accomplished independently for the expression, methylation and copy number profiles. The goals are to identify tumor sub-types that are etiologically distinct, to identify the risk factors that define specific sub-types, and to endeavor to characterize the key genes that appear to represent the principal features of the distinct sub-types.

Results

The analysis reveals strong evidence that gender represents an important factor that distinguishes disease sub-types. The sub-types defined using expression data and methylation data demonstrate considerable congruence and are also clearly correlated with mutations in important cancer genes. These sub-types are also strongly correlated with survival. The complexity of the data presents many analytical challenges including, prominently, the risk of false discovery.

Conclusions

Genomic profiling of tumors offers the opportunity to identify etiologically distinct sub-types, paving the way for a more refined understanding of cancer etiology.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2288-14-138) contains supplementary material, which is available to authorized users.

Von Hippel-Lindau (VHL) inactivation in sporadic clear cell renal cancer: associations with germline VHL polymorphisms and etiologic risk factors

Renal tumor heterogeneity studies have utilized the von Hippel-Lindau VHL gene to classify disease into molecularly defined subtypes to examine associations with etiologic risk factors and prognosis. The aim of this study was to provide a comprehensive analysis of VHL inactivation in clear cell renal tumors (ccRCC) and to evaluate relationships between VHL inactivation subgroups with renal cancer risk factors and VHL germline single nucleotide polymorphisms (SNPs). VHL genetic and epigenetic inactivation was examined among 507 sporadic RCC/470 ccRCC cases using endonuclease scanning and using bisulfite treatment and Sanger sequencing across 11 CpG sites within the VHL promoter. Case-only multivariate analyses were conducted to identify associations between alteration subtypes and risk factors. VHL inactivation, either through sequence alterations or promoter methylation in tumor DNA, was observed among 86.6% of ccRCC cases. Germline VHL SNPs and a haplotype were associated with promoter hypermethylation in tumor tissue (OR = 6.10; 95% CI: 2.28-16.35, p = 3.76E-4, p-global = 8E-5). Risk of having genetic VHL inactivation was inversely associated with smoking due to a higher proportion of wild-type ccRCC tumors [former: OR = 0.70 (0.20-1.31) and current: OR = 0.56 (0.32-0.99); P-trend = 0.04]. Alteration prevalence did not differ by histopathologic characteristics or occupational exposure to trichloroethylene. ccRCC cases with particular VHL germline polymorphisms were more likely to have VHL inactivation through promoter hypermethylation than through sequence alterations in tumor DNA, suggesting that the presence of these SNPs may represent an example of facilitated epigenetic variation (an inherited propensity towards epigenetic variation) in renal tissue. A proportion of tumors from current smokers lacked VHL alterations and may represent a biologically distinct clinical entity from inactivated cases.

2'-hydroxyflavanone inhibits proliferation, tumor vascularization and promotes normal differentiation in VHL-mutant renal cell carcinoma

Renal cell carcinoma (RCC) is one of the top ten cancers prevalent in USA. Loss-of-function mutations in the von Hippel-Lindau (VHL) gene constitute an established risk factor contributing to 75% of total reported cases of RCC. Loss-of-VHL leads to a highly vascularized phenotype of renal tumors. Intake of citrus fruits has been proven to reduce the risk of RCC in multicenter international studies. Hence, we studied the effect of 2'-hydroxyflavanone (2HF), an active anticancer compound from oranges, in RCC. Our in vitro investigations revealed that 2HF suppresses VHL-mutant RCC to a significantly greater extent than VHL-wild-type RCC by inhibiting epidermal growth factor receptor signaling, which is increased due to VHL mutations in RCC. Our results also revealed for the first time, that 2HF inhibits glutathione S-transferase pi activity. 2HF reduced cyclin B1 and CDK4 levels and induced G2/M phase arrest in VHL-mutant RCC. Importantly, 2HF inhibited the angiogenesis in VHL-mutant RCC by decreasing vascular endothelial growth factor expression. Our in vivo studies in mice xenografts confirmed our in vitro results as evident by decreased levels of proliferation marker, Ki67 and angiogenic marker, CD31, in 2HF-treated mice xenografts of VHL-mutant RCC. 2HF also increased the expression of E-cadherin in VHL-mutant RCC, which would be of significance in restoring normal epithelial phenotype. Collectively, our in vitro and in vivo results revealed the potent antiproliferative, anti-angiogenic and prodifferentiation properties of 2HF in VHL-mutant RCC, sparing normal cells, which could have significant implications not only in the specific management of VHL-mutant RCC but also towards other VHL syndromes.

Prognostic significance of Gremlin1 (GREM1) promoter CpG island hypermethylation in clear cell renal cell carcinoma

Gremlin1 (GREM1), a bone morphogenetic protein antagonist and putative angiogenesis-modulating gene, is silenced by promoter hypermethylation in human malignancies. Here we study GREM1 methylation in clear cell renal cell carcinoma (ccRCC) and its impact on tumor characteristics and clinical outcome. Three GREM1 promoter CpG island regions (i, ii, iii) were analyzed by methylation-specific PCR and/or bisulfite sequencing in ccRCC cell lines and ccRCCs from two independent patient series. Results were correlated with clinicopathological and angiogenic parameters. Bisulfite sequencing of ccRCC cell lines showed GREM1 methylation, associated with absence of GREM1 mRNA. GREM1 methylation prevalence in ccRCCs varied between regions: 55%, 24%, and 20% for regions i, ii, and iii, respectively. GREM1 region iii methylation was associated with increased tumor size (P = 0.02), stage (P = 0.013), grade (P = 0.04), tumor (P = 0.001), and endothelial cell (P = 0.0001) proliferation and decreased mean vessel density (P = 0.001) in a hospital-based ccRCC series (n = 150). In univariate analysis, GREM1 region iii methylated ccRCCs had a significant worse survival when compared with unmethylated ccRCCs (hazard ratio [HR] = 2.35, 95% confidence interval [CI]:1.29 to 4.28), but not in multivariate analysis (HR = 0.88, 95% CI: 0.45 to 1.74). In a population-based validation series (n = 185), GREM1 region iii methylation was associated with increased Fuhrman grade (P = 0.03) and decreased overall survival (P = 0.001) in univariate and multivariate analysis (HR = 2.32, 95% CI: 1.52 to 3.53 and HR = 2.27, 95% CI: 1.44 to 3.59, respectively). The strong correlation between GREM1 region iii promoter methylation and increased malignancy and its correlation with active angiogenesis indicates a role for GREM1 in ccRCC carcinogenesis and tumor angiogenesis.

Contemporary epidemiology of renal cell cancer

We analyzed renal cell cancer incidence patterns in the United States and reviewed recent epidemiologic evidence with regard to environmental and host genetic determinants of renal cell cancer risk. Renal cell cancer incidence rates continued to rise among all racial/ethnic groups in the United States, across all age groups, and for all tumor sizes, with the most rapid increases for localized stage disease and small tumors. Recent cohort studies confirmed the association of smoking, excess body weight, and hypertension with an elevated risk of renal cell cancer, and suggested that these factors can be modified to reduce the risk. There is increasing evidence for an inverse association between renal cell cancer risk and physical activity and moderate intake of alcohol. Occupational exposure to trichloroethylene has been positively associated with renal cell cancer risk in several recent studies, but its link with somatic mutations of the von Hippel-Lindau gene has not been confirmed. Studies of genetic polymorphisms in relation to renal cell cancer risk have produced mixed results, but genome-wide association studies with larger sample size and a more comprehensive approach are underway. Few epidemiologic studies have evaluated risk factors by subtypes of renal cell cancer defined by somatic mutations and other tumor markers.

Renal cell carcinoma

PURPOSE OF REVIEW

The recent contributions to renal cell carcinoma in the fields of molecular biology and the expanded use of molecularly targeted agents will be reviewed. This study is intended to update prognostic and therapeutic decision-making data and provide perspective on advances in understanding the molecular biology of this disease.

RECENT FINDINGS

Updates to the currently used prognostic algorithms for renal cell carcinoma are needed, and recently verified prognostic nomograms will be discussed. This comes in the wake of numerous advances in the use of molecularly targeted drugs, which will be reviewed. Finally, advancements in understanding the biology of renal cell carcinoma include the discovery of von Hippel-Lindau associated mechanisms involved in renal cyst formation and renewed appreciation for the influence of this pathway on the tumor cell glucose utilization profile.

SUMMARY

Renal cell carcinoma continues to evolve swiftly with the approval of new agents and the maturation of clinical trials to provide relevant structure to treatment decisions. This study will give an overview of the latest concepts in the epidemiology and biology of renal cell carcinoma and provide current surgical and systemic updates for managing renal cell carcinoma.

BPDE induced lymphocytic chromosome 3p deletions may predict renal cell carcinoma risk

PURPOSE

Cigarette smoking is a risk factor for renal cell carcinoma. BPDE (benzo[alpha]pyrene diol epoxide) (Midwest Research Institute, Kansas City, Missouri), which is a major constituent of cigarette smoke, induces 3p aberrations that are associated with susceptibility to other smoking associated cancers. Because chromosome 3p deletions are known to be the most frequent genetic alterations in renal cell carcinoma, we tested whether 3p sensitivity to BPDE predicts susceptibility to renal cell carcinoma.

MATERIALS AND METHODS

Cultured peripheral blood lymphocytic cells from 170 cases and 135 controls were treated with 2 microM BPDE for 24 hours and assessed for 3p deletions by fluorescence in situ hybridization using probes directed to 3p25.2, 3p21.3, 3p14.2 and 3p12.2. A probe for 3q13 served as a control. One thousand lymphocyte interphases were scored per sample.

RESULTS

At each locus BPDE induced 3p deletions were significantly more common in cases than in controls. No significant differences between cases and controls were observed for deletions in 3q13. Using the median value in controls as the cutoff point for BPDE sensitivity we found that the OR in subjects with high BPDE sensitivity at 3p25.2, 3p21.3, 3p14.2 and 3p12.2 was 2.02 (95% CI 1.18-3.46), 2.28 (95% CI 1.33-3.92), 1.84 (95% CI 1.07-3.16) and 1.97 (95% CI 1.15-3.37), respectively. There were dose dependent relationships between the number of deletions at each locus and the risk of renal cell carcinoma.

CONCLUSIONS

This study demonstrates that chromosome 3p may be a specific molecular target of cigarette carcinogens and BPDE sensitivity in chromosome 3p may reflect the genetic susceptibility of an individual to renal cell carcinoma.

Polymorphisms in genes related to activation or detoxification of carcinogens might interact with smoking to increase renal cancer risk: results from The Netherlands Cohort Study on diet and cancer

Metabolic gene polymorphisms have previously been suggested as risk factors for renal cell carcinoma (RCC). These polymorphisms are involved in activation or detoxification of carcinogens in cigarette smoke which is another RCC risk factor. We evaluated gene-environment interactions between CYP1A1, GSTmicro1 and smoking in a large population-based RCC case group. The Netherlands Cohort Study on diet and cancer (NLCS) comprises 120,852 persons who completed a questionnaire on smoking and other risk factors at baseline. After 11.3 years of follow-up, 337 incident RCC cases were identified. DNA was collected for 245 cases. In a case-only analysis, interaction-odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using logistic regression. We observed a moderate, not statistically significant, interaction between current smoking and CYP1A1*2C (OR 1.42; 95% CI 0.70-2.89) and GSTmicro1 null (OR 1.35; 95% CI 0.65-2.79). For current smokers with both a variant (heterozygous or homozygous) in CYP1A1 and GSTmicro1 null, risk was also increased (OR 1.63; 95% CI 0.63-4.24). No interaction was observed between ever smokers, smoking duration (increments of 10 smoking years) or amount (increments of 5 cigarettes/day) and CYP1A or GSTmicro1. Our results show a modest trend towards a statistically significant gene-environment interaction between CYP1A1, GSTmicro1 and smoking in RCC. This could indicate that RCC risk among smokers might be more increased with the CYP1A1*2C genotype, GSTmicro1 null, or both a CYP1A1 variant and GSTmicro1 null.

Cigarette smoking, von Hippel-Lindau gene mutations and sporadic renal cell carcinoma

We investigated whether smoking is associated with mutations in the Von Hippel–Lindau (VHL) gene in 337 cases of sporadic renal cell carcinoma (RCC) among 120 852 people followed for 11.3 years; the findings suggest that smoking causes RCC independently of VHL gene mutations.