Gene-environment interactions in renal cell carcinoma

LncRNA GAS5 rs145204276 Polymorphism Reduces Renal Cell Carcinoma Susceptibility in Southern Chinese Population

Objective

Methods

Results

Conclusions

Genetic Variant in Long Non-Coding RNA H19 Modulates Its Expression and Predicts Renal Cell Carcinoma Susceptibility and Mortality

The long non-coding RNA (lncRNA) H19 has been demonstrated to play a crucial role in carcinogenesis, including renal cell carcinoma (RCC). However, the impact of genetic variations in H19 gene on RCC has not been investigated before. In the present study, we sought to evaluate whether genetic polymorphisms in H19 are related to the susceptibility and mortality of RCC. We genotyped four widely studied polymorphisms in H19 and assessed their relationship with susceptibility and prognosis of RCC in a case-control study compromising 1,027 cases and 1,094 controls. The functionality of the important polymorphism was further investigated by real-time polymerase chain reaction and luciferase reporter assay. We found that H19 rs2839698 was significantly associated with risk and prognosis of RCC. Compared with the H19 rs2839698 CC genotype, the variant genotypes (CT/TT) were significantly associated with increased risk of RCC (P = 0.023, OR = 1.21; 95% CI = 1.03–1.45). Besides, patients with variant genotypes (CT/TT) were more likely to develop large tumor (P = 0.003, OR = 1.47; 95% CI = 1.16–1.85) and advanced disease (P = 0.010, OR = 1.59; 95% CI = 1.12–2.26); and had a significantly unfavorable overall survival than those with the rs2839698 CC genotype (CT/TT vs. CC: Log-rank P = 0.026, HR = 2.25, 95%CI = 1.07–4.75). Furthermore, the CT/TT genotypes were associated with significantly increased expression of H19 in renal tissue. The luciferase reporter assays revealed the potential effect of rs2839698 variant on the binding of microRNAs to H19. Our results suggest that the H19 rs2839698 variant may be a genetic predictor of susceptibility and mortality of RCC. The risk effects and the functional impact of the variant on H19 still need further validation.

Association between ACYP2 polymorphisms and the risk of renal cell cancer

Background

Kidney cancer is the predominant form of malignancy of the kidney and accounts for approximately 3%–4% of all cancers. Renal cell cancer (RCC) represents more than 85% of kidney cancer. It has been reported that genetic factors may predispose individuals to RCC. This study evaluated the association between Acylphosphatase 2 (ACYP2) gene polymorphisms and RCC risk in the Han Chinese population.

Methods

Twelve single‐nucleotide polymorphisms (SNPs) in ACYP2 were genotyped using the Agena MassARRAY platform from 293 RCC patients and 495 controls. The Chi‐squared test, genetic models, haplotype, and stratification analyses were used to evaluate the association between SNPs and the risk of RCC. The relative risk was estimated using the odds ratio (OR) and 95% confidence interval (CI).

Results

We observed that the rs6713088 allele G (OR = 1.26, 95% CI: 1.03–1.53, p = .023) and rs843711 allele T (OR = 1.29, 95% CI: 1.06–1.57, p = .010) were associated with increased RCC risk. Genetic model analyses found that rs843711 was significantly associated with an increased RCC risk under the recessive model and log‐additive model after adjusting for age and gender. Haplotype analysis showed that the haplotype “TTCTCGCC” (OR = 0.67, 95% CI: 0.48–0.94, p = .021) was associated with a decreased risk of RCC in the Han Chinese population. Stratification analysis also found that rs6713088 and rs843711 were significantly associated with increased RCC risk.

Conclusion

In summary, the results suggested that ACYP2 polymorphisms could be used as a genetic marker for RCC. Additional functional and association studies are required to validate our results.

Treating the Chameleon: Radiotherapy in the management of Renal Cell Cancer

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Conventional fractionated radiotherapy (RT) is predominantly used for the palliation of symptomatic metastatic disease.

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Hypofractionated stereotactic RT is increasingly adopted for the treatment of locally recurrent and oligometastatic disease.

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High-dose radiation seems to have an immunogenic effect in patients with renal cell cancer.

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Combinations of ablative RT with immunotherapies are promising approaches that might improve outcomes.

Purpose

To review the role of radiotherapy (RT) in the treatment of renal cell cancer (RCC) in the curative and palliative setting.

Content

Details related to the clinical outcomes of primary, preoperative, postoperative and palliative RT are discussed, along with a presentation of the established role of surgery and systemic therapy. An overview of data derived from mono- and multi-institutional trials is provided.

Conclusion

Radiotherapy has been shown to provide good symptom palliation and local control in RCC depending on the dose that can be delivered. There is emerging data suggesting that with the use of high-precision RT methods the indication spectrum of RT can be exploited covering different clinical situations particularly for unresectable local recurrences and oligometastatic disease.

miR-502-mediated histone methyltransferase SET8 expression is associated with clear cell renal cell carcinoma risk

Genetic variants may affect the interactions between microRNAs (miRNAs/miRs) and their target genes by modulating their binding affinity or by creating, or destroying a miRNA-binding site. SET domain containing (lysine methyltransferase) 8 (SET8) is the sole lysine methyltransferase that catalyzes the monomethylation of histone H4 lysine 20, and is associated with tumor growth, invasion and metastasis. In the present study, the rs16917496 polymorphism within the miR-502 binding site of the SET8 mRNA 3' untranslated region (3'UTR) in patients with clear cell renal cell carcinoma (ccRCC) and healthy controls was genotyped. The SET8 CC genotype was associated with a decreased ccRCC risk compared with the CT [P=0.003; odds ratio (OR)=0.318; 95% confidence interval (CI), 0.146-0.691], TT (P=0.011; OR=0.402; 95% CI, 0.197-0.819) and CT+TT (P=0.004; OR=0.370; 95% CI, 0.186-0.736) genotypes. The SET8 CC genotype was associated with reduced SET8 expression based on immunostaining of ccRCC tissue. Low SET8 protein levels were negatively associated with tumor-node-metastasis staging in patients with ccRCC according to the size of tumor and lymph node metastases. SET8-knockdown inhibited renal carcinoma 786-O cell proliferation, migration and invasion. c-Myc and matrix metalloproteinase-7 mRNA expression were downregulated upon SET8-knockdown in renal carcinoma 786-O cells. These data indicated that SET8 may be a functional tumor promoter and that its activation, which is partially regulated by changing the miR-502 and SET8 3'UTR binding affinity, may serve an important role in ccRCC development.

Logistic Bayesian LASSO for genetic association analysis of data from complex sampling designs

Detecting gene-environment interactions with rare variants is critical in dissecting the etiology of common diseases. Interactions with rare haplotype variants (rHTVs) are of particular interest. At the same time, complex sampling designs, such as stratified random sampling, are becoming increasingly popular for designing case-control studies, especially for recruiting controls. The US Kidney Cancer Study (KCS) is an example, wherein all available cases were included while the controls at each site were randomly selected from the population by frequency matching with cases based on age, sex and race. There is currently no rHTV association method that can account for such a complex sampling design. To fill this gap, we consider logistic Bayesian LASSO (LBL), an existing rHTV approach for case-control data, and show that its model can easily accommodate the complex sampling design. We study two extensions that include stratifying variables either as main effects only or with additional modeling of their interactions with haplotypes. We conduct extensive simulation studies to compare the complex sampling methods with the original LBL methods. We find that, when there is no interaction between haplotype and stratifying variables, both extensions perform well while the original LBL methods lead to inflated type I error rates. However, when such an interaction exists, it is necessary to include the interaction effect in the model to control the type I error rate. Finally, we analyze the KCS data and find a significant interaction between (current) smoking and a specific rHTV in the N-acetyltransferase 2 gene.

Epidemiology of Renal Cell Carcinoma

The increasing incidence of RCC in most populations may in part be due to increasing numbers of incidentally detected cancers with new imaging methods. Further, the increase is not only limited to small local tumours but also includes more advanced tumours, which may to some part explain the still high mortality rates. The variation in incidence between populations may have several other explanations. Traditionally the starting point has included thoughts of environmental exposures, which so far have only in part explained the causes of RCC, by means of cigarette smoking and obesity, which may account for approximately 40% of cases in high-risk countries (Table 2). Further, the genetic variations may be of importance as a cause of the difference between populations. Continued research in RCC is needed with the knowledge that nearly 50% of patients die within 5 years after diagnosis. The further search for environmental exposures should take in account the knowledge that RCC consists of different types with specific genetic molecular characteristics. These genetic alterations have in some cases been suggested to be associated with specific exposures. Furthermore, there might exist a modulating effect of genetic polymorphisms among metabolic activation and detoxification enzymes. Hence, a further understanding of the genetic and molecular processes involved in RCC will hopefully give us a better knowledge how to analyse and interpret exposure associations that have importance for both initiation and progression of RCC.

Concurrent angiomyolipomas and renal cell neoplasms in patients without tuberous sclerosis: a retrospective study

Synchronous renal cell neoplasms (RCNs) and angiomyolipomas (AML) occurring in the same kidney are rare. The aim of this retrospective study is to investigate the incidence and clinicopathological features of concurrent AML and RCN in patients without tuberous sclerosis complex (TSC). Partial and radical nephrectomy specimens with a diagnosis of RCN and AML from 1995 to May 2013 were reviewed. Cases were assessed for histological subtype of AML and RCN, topographic relationship between the AML and the RCN, and clinical characteristics. A total of 565 RCNs and 19 AMLs were identified. Of 19 cases of AML, 9 (47%) were associated with renal tumors. Clear-cell renal cell carcinoma (RCC) was the most common malignancy associated with AML (56%). The mean age of patients with concomitant AML and RCN was higher than the mean age of patients with only AML (58.6 vs 55.5 years). The majority of patients with concomitant AML and RCN were female (78%). All concurrent sporadic AMLs were benign. We identified one case of bilateral clear-cell RCC with concomitant multiple bilateral AMLs in a patient with TSC.

Genetic variants in RKIP are associated with clear cell renal cell carcinoma risk in a Chinese population

Background

Raf-1 kinase inhibitor protein (RKIP) plays a critical role in tumor development by regulating cell functions such as invasion, apoptosis and differentiation. Down-regulation of RKIP expression has been implicated in the development and progression of renal cell carcinoma (RCC). Herein, we hypothesized that genetic polymorphisms in RKIP might be associated with susceptibility and progression of RCC.

Methods

A total of 5 tagging single-nucleotide polymorphisms (tSNPs) in RKIP were selected and genotyped by SNapShot method in a case-control study of 859 RCC patients and 1004 controls. The logistic regression was used to evaluate the genetic association with occurrence and progression of RCC. The functionality of the important SNP was preliminary examined by qRT-PCR.

Result

We found that the rs17512051 in the promoter region of RKIP was significantly associated with decreased clear cell RCC (ccRCC) risk (TA/AA vs. TT: P = 0.039, OR = 0.78, 95%CI = 0.62–0.99). Another SNP (rs1051470) in the 3′UTR region of RKIP was marginally associated with increased ccRCC risk (TT vs. CC+CT: OR = 1.45, 95%CI = 1.01–2.09). In the stratified analysis, the protective effect of rs17512051 was more predominant in the subgroups of male, non-smokers, non-drinkers as well as subjects without history of diabetes. Furthermore, we observed higher RKIP mRNA levels in the presence of the rs17512051A allele in normal renal tissues.

Conclusion

Our results suggest that the potentially functional RKIP rs17512051 polymorphism may affect ccRCC susceptibility through altering the endogenous RKIP expression level. Risk effects and the functional impact of this polymorphism need further validation.

ASC-J9 suppresses renal cell carcinoma progression by targeting an androgen receptor-dependent HIF2α/VEGF signaling pathway

Males have a higher incidence of renal cell carcinoma (RCC) than females, but the reason for this gender difference is unknown. Addressing this question, we report the discovery of an androgen receptor (AR)-induced HIF2α/VEGF signal that drives RCC progression. AR attenuation or augmentation in RCC cells altered their proliferation, migration, and invasion in multiple models in vitro and in vivo. Mechanistic investigations revealed that AR targeting inhibited RCC cell migration and invasion by modulating HIF2α/VEGF signals at the level of mRNA and protein expression. Interrupting HIF2α/VEGF signals with inhibitors of either HIF2α or VEGF was sufficient to suppress RCC progression. Similarly, the specific AR degradation enhancer ASC-J9 was sufficient to suppress AR-induced HIF2α/VEGF signaling and RCC progression in multiple models in vitro and in vivo. Taken together, our results revealed a novel role for AR in RCC initiation and progression with implications for novel therapeutic strategies.

Genetic variation in the GSTM3 promoter confer risk and prognosis of renal cell carcinoma by reducing gene expression

Background:

Glutathione S-transferase mu 3 (GSTM3) has been proven to be downregulated in renal cell carcinoma (RCC). We aimed to characterise the role of GSTM3 and its genetic predisposition on the occurrence and postoperative prognosis of RCC.

Methods:

The effect of GSTM3 on RCC aggressiveness was examined using transfection and silencing methods. Glutathione S-transferase mu 3 expression in renal tissues was examined by immunohistochemistry. The associations of rs1332018 (A-63C) and rs7483 (V224I) polymorphisms with RCC risk were examined using 400 RCC patients and 802 healthy controls. The factors contributing to postoperative disease-specific survival of RCC patients were evaluated using the Cox proportional hazard model.

Results:

Glutathione S-transferase mu 3 silencing increased the invasion and anchorage-independent growth of RCC cell lines. rs1332018 (AC+CC vs AA), which correlated with low expression of GSTM3 in kidney, was associated with RCC risk (odds ratio, 1.446; 95% confidence interval (CI), 1.111–1.882). rs1332018 variants and low GSTM3 expression significantly predicted unfavourable postoperative survivals of RCC patients (P<0.05). rs1332018 variants independently predicted a poor prognosis (hazard ratio, 2.119; 95% CI, 1.043–4.307).

Conclusion:

Glutathione S-transferase mu 3 may function as a tumour suppressor in RCC. rs1332018 genetic variants predispose the host to downregulating GSTM3 expression in kidney, facilitate carcinogenesis, and predict an unfavourable postoperative prognosis of RCC.

Cancer incidence among adolescents and young adults in urban Shanghai, 1973-2005

BACKGROUND

Lack of cancer incidence information for adolescents and young adults led us to describe incidence trends within the young population of 15 to 49 year-olds in urban Shanghai between 1973 and 2005.

METHODS

During 1973 to 2005, data on 43,009 (45.8%) male and 50,828 (54.2%) female cancer cases aged 15-49 years from the Shanghai Cancer Registry were analyzed. Five-year age-specific rates, world age-standardized rates, percent change (PC), and annual percent change (APC) were calculated using annual data on population size and its estimated age structure.

RESULTS

During the 33-year study period, overall cancer incidence of adolescents and young adults among males marginally decreased by 0.5% per year (P<0.05). However, overall cancer incidence for females slightly increased by 0.8% per year (P<0.05). The leading cancer for males in rank were liver, stomach, lung, colorectal, and nasopharyngeal cancers and for females were breast, stomach, colorectal, thyroid, and ovarian cancers. Among specific sites, incidence rates significantly decreased for cancers of the esophagus, stomach, and liver in both sexes. In contrast, incidence rates significantly increased for kidney cancers, non-Hodgkin lymphoma, and brain and nervous system tumors in both sexes and increased for breast and ovarian cancers among females.

CONCLUSIONS

Overall cancer incidence rates of adolescents and young adults decreased in males whereas they increased in females. Our findings suggest the importance of further epidemiology and etiologic studies to further elucidate factors contributing to the cancer incidence trends of adolescents and young adults in China.

Xenobiotic metabolizing gene variants and renal cell cancer: a multicenter study

BACKGROUND

The countries of Central and Eastern Europe have among the highest worldwide rates of renal cell cancer (RCC). Few studies have examined whether genetic variation in xenobiotic metabolic pathway genes may modify risk for this cancer.

METHODS

The Central and Eastern Europe Renal Cell Cancer study was a hospital-based case-control study conducted between 1998 and 2003 across seven centers in Central and Eastern Europe. Detailed data were collected from 874 cases and 2053 controls on demographics, work history, and occupational exposure to chemical agents. Genes [cytochrome P-450 family, N-acetyltransferases,

NAD(P)H

quinone oxidoreductase I (NQO1), microsomal epoxide hydrolase (mEH), catechol-O-methyltransferase (COMT), uridine diphosphate-glucuronosyltransferase (UGT)] were selected for the present analysis based on their putative role in xenobiotic metabolism. Haplotypes were calculated using fastPhase. Odds ratios and 95% confidence intervals were estimated by unconditional logistic regression adjusted for country of residence, age, sex, smoking, alcohol intake, obesity, and hypertension.

RESULTS

We observed an increased risk of RCC with one SNP. After adjustment for multiple comparisons it did not remain significant. Neither NAT1 nor NAT2 slow acetylation was associated with disease.

CONCLUSION

We observed no association between this pathway and renal cell cancer.

Functional promoter -31G>C variant in survivin gene is associated with risk and progression of renal cell cancer in a Chinese population

Background

Survivin is an inhibitor of apoptosis protein and is involved in the occurrence and progression of human malignancies. Recently, a functional polymorphism (−31G>C, rs9904341) in the promoter of survivin has been shown to influence its expression and confer susceptibility to different types of cancer. The present study was aimed to investigate whether the polymorphism also influences susceptibility and progression of renal cell cancer (RCC) in a Chinese population.

Methods

We genotyped this polymorphism using the TaqMan assay in a case-control study comprised of 710 RCC patients and 760 controls. The logistic regression was used to assess the genetic association with occurrence and progression of RCC.

Results

Compared with the genotypes containing G allele (GG and GC), we found a statistically significant increased occurrence of RCC associated with the CC genotype [P = 0.006, adjusted odds ratio (OR) = 1.38, 95% confidence interval (CI) = 1.08–1.76]. The polymorphism was associated with risk of developing advanced stage (OR = 2.02, 95%CI = 1.34–3.07) and moderately differentiated (OR = 1.75; 95%CI = 1.20–2.54) RCC. Furthermore, the patients carrying the CC genotype had a significantly greater prevalence of high clinical stage disease (P_trend = 0.003). Similar results were also observed when we restricted the analysis to clear cell RCC, a major histological type of RCC.

Conclusions

Our results suggest that the functional −31G>C polymorphism in the promoter of survivin may influence the susceptibility and progression of RCC in the Chinese population. Large population-based prospective studies are required to validate our findings.

Epidemiology of renal cell cancer

Renal cell cancer (RCC) is increasingly diagnosed at an early stage in many countries, which likely contributes to the recent leveling of RCC mortality in the United States and many European countries. However, over all stages nearly 50% of the patients die within 5 years after diagnosis. Smoking and obesity may account for approximately 40% of all incidental cases in high-risk countries. Besides obesity, rising prevalence of hypertension may play a growing role. Several other occupational and lifestyle factors may also affect the risk of RCC. Genetic variations may be an important factor in the differing incidence among populations.

Risk factor for clear cell renal cell carcinoma in Chinese population: a case-control study

BACKGROUND

Risk factors for clear cell renal cell carcinoma (ccRCC) differ among populations and remain controversial. We carried out a hospital-based case-control study to examine the effects of health status, lifestyle, and some genetic polymorphisms on ccRCC risk in Chinese subjects.

METHODS

Between 2007 and 2009, 250 newly diagnosed, histologically confirmed ccRCC cases and 299 sex-, age-matched healthy controls provided complete information including consumption of tea and alcohol, smoking, occupational exposure, body mass index (BMI), hypertension, diabetes, and urolithiasis by face-to-face interview in Shanghai. Genetic polymorphisms of cytochrome P450 mono-oxygenase (CYP1A1: 6235T>C, 4889A>G, and 4887C>A), glutathione S-transferase (GSTP1: 342A>G), and N-acetyltransferase (NAT2: 481C>T, 590G>A, and 857G>A) were identified by PCR-RFLP and DNA sequencing. Adjusted odds ratio (AOR) and 95% confidence interval (CI) were derived through multivariate logistic regression.

RESULTS

Green tea intake (≥500 ml/d) was inversely associated with ccRCC risk, with an AOR of 0.34 (95% CI 0.21-0.55). BMI (≥25 kg/m(2)), hypertension, and urolithiasis were independently associated with an increased risk of ccRCC, with AOR (95% CI) of 2.10 (1.32-3.34), 2.49 (1.57-3.93), and 3.33 (1.12-9.89), respectively. No association was observed between smoking, alcohol consumption, or occupational exposure with ccRCC risk. The polymorphisms and their interactions with the environmental exposures were mostly not associated with ccRCC risk.

CONCLUSION

BMI (≥25 kg/m(2)), hypertension, and urolithiasis are independently associated with an increased risk, whereas green tea intake (≥500 ml/d) is independently associated with a decreased risk of ccRCC. The polymorphisms of the xenobiotic-metabolizing enzymes are weakly associated with ccRCC risk in Chinese subjects.

TFE3 Translocation-Associated Renal Cell Carcinoma Presenting as Avascular Necrosis of the Femur in a 19-Year-Old Patient: Case Report and Review of the Literature

In the United States, renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and 90–95% of all neoplasms arising from the kidney. According to the National Cancer Institute, 58 240 new cases and 13 040 deaths from renal cancer will occur in 2010. RCC usually occurs in older adults between the ages of 50 and 70 and is rare in young adults and children. We describe a case of a TFE3 translocation-associated RCC in a 19-year-old patient presenting as avascular necrosis of the femur. Due to the rarity of this malignancy, we present this case including a review of the existing literature relative to diagnosis and treatment.

Epidemiology and risk factors for kidney cancer

After more than two decades of rising rates, in recent years the total kidney cancer incidence worldwide has shown signs of stabilizing, or even decreasing. In adults, kidney cancer consists of renal cell carcinoma (RCC), the predominant form, and renal transitional cell carcinoma (RTCC); these types primarily arise in the renal parenchyma and renal pelvis, respectively. Although temporal trends by kidney cancer type are not well established worldwide, incidence of RCC in the US has continued to rise, mainly for early-stage tumors, while that of RTCC has declined, and total kidney cancer mortality rates have leveled. Stabilization of kidney cancer mortality rates has also been reported in Europe. These trends are consistent with reports of increasing incidental diagnoses and a downward shift in tumor stage and size in clinical series. The changing prevalence of known risk factors for RCC, including cigarette smoking, obesity, and hypertension, is also likely to affect incidence trends, although their relative impact may differ between populations. Accumulating evidence suggests an etiologic role in RCC for physical activity, alcohol consumption, occupational exposure to trichloroethylene, and high parity among women, but further research is needed into the potential causal effects of these factors. Genetic factors and their interaction with environmental exposures are believed to influence risk of developing RCC, but a limited number of studies using candidate-gene approaches have not produced conclusive results. Large consortium efforts employing genome-wide scanning technology are underway, which hold promise for novel discoveries in renal carcinogenesis.

Epidemiologic characteristics and risk factors for renal cell cancer

Incidence rates of renal cell cancer, which accounts for 85% of kidney cancers, have been rising in the United States and in most European countries for several decades. Family history is associated with a two- to four-fold increase in risk, but the major forms of inherited predisposition together account for less than 4% of renal cell cancers. Cigarette smoking, obesity, and hypertension are the most consistently established risk factors. Analgesics have not been convincingly linked with renal cell cancer risk. A reduced risk of renal cell cancer among statin users has been hypothesized but has not been adequately studied. A possible protective effect of fruit and vegetable consumption is the only moderately consistently reported dietary finding, and, with the exception of a positive association with parity, evidence for a role of hormonal or reproductive factors in the etiology of renal cell cancer in humans is limited. A recent hypothesis that moderate levels of alcohol consumption may be protective for renal cell cancer is not strongly supported by epidemiologic results, which are inconsistent with respect to the categories of alcohol consumption and the amount of alcohol intake reportedly associated with decreased risk. For occupational factors, the weight of the evidence does not provide consistent support for the hypotheses that renal cell cancer may be caused by asbestos, gasoline, or trichloroethylene exposure. The established determinants of renal cell cancer, cigarette smoking, obesity, and hypertension, account for less than half of these cancers. Novel epidemiologic approaches, including evaluation of gene–environment interactions and epigenetic mechanisms of inherited and acquired increased risk, are needed to explain the increasing incidence of renal cell cancer.

Lifestyle Factors, Exposures, Genetic Susceptibility, and Renal Cell Cancer Risk: A Review

Malignant kidney tumors account for approximately 2% of all new primary cancer cases diagnosed in the United States, with an estimated 30,000 cases occurring annually. Although a variety of agents, chemical and biological, have been implicated as causal agents in the development of renal cell carcinoma (RCC), the etiology remains enigmatic. The strongest association has been developed between cigarette smoking and renal cancer however consistent, positive associations between RCC and obesity, diabetes, and hypertension have also been reported. In addition, more recent investigations of familial kidney cancer syndromes indicate that a strong genetic component contributes to RCC development. Several genes have been identified through investigation of familial kidney cancer syndromes. This review article describes recent trends in RCC incidence and the currently identifiable etiological causes that account for approximately half of the RCC cases diagnoses. The remainder of this review then focuses on additional risk factors that have thus far not been well examined but may be helpful in explaining the increasing incidence trends and the geographic or racial variation observed nationally and worldwide.

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.

Accurate classification of MLH1/MSH2 missense variants with multivariate analysis of protein polymorphisms-mismatch repair (MAPP-MMR)

Lynch syndrome, also known as hereditary nonpolyposis colon cancer (HNPCC), is the most common known genetic syndrome for colorectal cancer (CRC). MLH1/MSH2 mutations underlie approximately 90% of Lynch syndrome families. A total of 24% of these mutations are missense. Interpreting missense variation is extremely challenging. We have therefore developed multivariate analysis of protein polymorphisms-mismatch repair (MAPP-MMR), a bioinformatic algorithm that effectively classifies MLH1/MSH2 deleterious and neutral missense variants. We compiled a large database (n>300) of MLH1/MSH2 missense variants with associated clinical and molecular characteristics. We divided this database into nonoverlapping training and validation sets and tested MAPP-MMR. MAPP-MMR significantly outperformed other missense variant classification algorithms (sensitivity, 94%; specificity, 96%; positive predictive value [PPV] 98%; negative predictive value [NPV], 89%), such as SIFT and PolyPhen. MAPP-MMR is an effective bioinformatic tool for missense variant interpretation that accurately distinguishes MLH1/MSH2 deleterious variants from neutral variants.

MDM2 SNP309 polymorphism as risk factor for susceptibility and poor prognosis in renal cell carcinoma

PURPOSE

MDM2 is a major negative regulator of p53, and a single nucleotide polymorphism in the MDM2 promoter region SNP309 (rs2279744) has been shown to increase the affinity of the transcriptional activator Sp1, resulting in elevated MDM2 transcription and expression in some cancers. There is currently no information about the role of MDM2 polymorphism in renal cell carcinoma (RCC). We investigated polymorphisms in p53-related genes, including MDM2, and their interactions in renal cancer.

EXPERIMENTAL DESIGN

We genotyped three single nucleotide polymorphisms of three genes (p53 Arg(72)Pro, p21 Ser(31)Arg, and MDM2 SNP309) in 200 patients with renal cancer and 200 age- and gender-matched healthy subjects. Genotyping was confirmed by direct DNA sequencing. Samples that showed significant polymorphic variants were analyzed for MDM2 expression by immunohistochemistry. Association of polymorphic variants on survival of RCC patients was analyzed by Kaplan-Meier curves.

RESULTS

A significant increase in the GG genotype of the MDM2 SNP309 was observed in RCC patients compared with healthy controls (odds ratio, 1.80; 95% confidence interval, 1.14-2.84). To investigate the effect of the MDM2 SNP309 polymorphism on MDM2 expression, immunohistochemistry was done in genotyped RCC tissues. Positive staining for MDM2 was detected in 2 of 15 (13%) TT genotype, 4 of 15 (26%) TG genotype, and 5 of 10 (50%) GG genotype carriers. The frequency of MDM2 expression in GG genotype carriers was significantly higher than that in TT genotype carriers. Polymorphisms of p53 Arg(72)Pro and p21 Ser(31)Arg did not show significant association with RCC. In univariate and multivariate analysis, MDM2 SNP309 GG genotype was independently associated with poor prognosis. Kaplan-Meier curve analysis showed that survival of patients with GG carriers was significantly worse than that of carriers with TG + TT genotypes.

CONCLUSIONS

This is the first report to show a significant association between functional polymorphisms in MDM2 and increased risk of developing renal cancer. In addition, the MDM2 polymorphism was shown to be an independent adverse prognostic factor for RCC. Patients with MDM2 309GG genotype showed worse prognosis and low survival.

Risk assessment of renal cell carcinoma using alkaline comet assay

BACKGROUND

DNA damage induced by mutagens has been associated with an individual's susceptibility to cancer.

METHODS

In the current study, which involved 193 renal cell carcinoma (RCC) patients and 193 controls, DNA damage before mutagen induction (baseline), after benzo(alpha)pyrene dio epoxide (BPDE) treatment, and after gamma-radiation induction were assayed by comet assay in peripheral blood lymphocytes. Olive tail moments were used as DNA damage parameters. The 5 variables that were analyzed for their associations with RCC risk were baseline, BPDE-induced, gamma-radiation-induced, net BPDE-induced (BPDE-induced subtract baseline), and net gamma-radiation-induced (gamma-radiation-induced subtract baseline) Olive tail moments.

RESULTS

Significantly higher Olive tail moments were observed in cases compared with controls at baseline (1.95 vs 1.65; P = .008), after BPDE induction (3.10 vs 2.38; P < .001), and after gamma-radiation induction (4.25 vs 3.47; P < .001). The net BPDE-induced and gamma-radiation-induced DNA damage was also found to be significantly higher in cases compared with controls (P < .001 for both mutagens). Using the 75th percentile Olive tail moments in the controls as the cutoff point, the authors found that high levels of baseline DNA damage, BPDE-induced DNA damage, and gamma-radiation-induced DNA damage were associated with significantly increased risks of RCC, with odds ratios of 1.96 (95% confidence interval [95% CI], 1.26-3.06), 2.70 (95% CI, 1.72-4.23), and 3.13 (95% CI, 1.99-4.92), respectively. Similarly, net BPDE-induced and net gamma-radiation-induced DNA damages were also found to be significantly associated with elevated risks of RCC.

CONCLUSIONS

The results of the current study suggest that both baseline and mutagen-induced DNA damages assessed by comet assay are associated with an increased risk of RCC.

Differential gene expression identifies subgroups of renal cell carcinoma

Clear cell carcinoma of the kidney, the most common subtype of renal cell cancer, displays different biological behavior in different patients. This heterogeneity cannot be recognized by light microscopy. In this study, gene expression in 16 clear cell renal cell carcinoma samples and 17 non-malignant tissue types comprising 539 samples was determined using oligonucleotide microarrays representing approximately 40,000 known genes and ESTs. Differences in gene expression were quantified as the fold change in gene expression between the various sets of samples. A set of genes was identified that was overexpressed in the renal cell carcinoma samples compared with the normal kidney samples. Principle component analysis of the set of renal cell carcinomas using this set of genes overexpressed in renal cell cancer revealed the existence of 2 major subgroups among the renal carcinomas. A series of principle component analyses of the set of renal cell carcinomas using different gene sets composed of genes involved in different metabolic pathways also revealed the same 2 major subgroups of the renal cell cancers. Eisen clustering using the same genes also revealed the same 2 major renal cell cancer subsets. Review of the pathology suggested that these 2 subgroups differed in pathologic grade. Genes differentially expressed between the 2 renal cell cancer subsets were identified. Examination of gene expression in each renal cell cancer subset and the pool of renal cell carcinoma samples compared with that in 17 different normal tissues revealed genes specifically overexpressed in renal cell cancer compared with these normal tissues. The authors conclude that gene expression patterns may be useful in helping to further classify subtypes of renal cell carcinoma that may have clinical significance. In addition, the genes identified as overexpressed in each set of clear cell renal cell carcinomas compared with normal tissues may represent useful targets for therapy.

Smoking may cause genetic alterations at 5q22.2 approximately q23.1 in clear-cell renal cell carcinoma

The aim of this study was to examine the relationship between allelic imbalance (AI) on chromosome 5q and clinico-pathologic parameters, including cigarette smoking. We examined the AI on chromosome 5q in 119 clear-cell renal cell carcinomas (CRCC) by a fluorescent polymerase chain reaction technique using nine microsatellite markers. AI of one or more loci was found in 43 cases (36.1%). The most frequent AI was observed at chromosome 5q23.1 (D5S467), where the LOX gene is located. The minimally involved region ranged from 5q22.1 to 5q23.2, with a possible breakpoint between 5q22 and 5q22.1. Regarding the relationships between the frequency of AI and the clinico-pathologic and environmental backgrounds, smokers had a significantly higher frequency of AI of 5q22.2 approximately q22.3 (D5S471) than nonsmokers (P = 0.013). No other significant associations were found between AI of specific loci and other parameters. Our results suggest that AI at 5q plays an important role in the genesis of CRCC. In addition, smoking may cause genetic alterations at 5q22.2 approximately q23.1, where the LOX gene is located.

Association of the BCRP C421A polymorphism with nonpapillary renal cell carcinoma

Breast cancer resistance protein (BCRP), the second member of the ATP-binding cassette membrane transporter family, has a single nucleotide polymorphism, C421A (resulting in Q141K), that is of functional importance. Our aim was to explore the relationship between this polymorphism of the BCRP gene and the risk of renal cell carcinoma (RCC) development. For a case-control study, DNA samples from 200 nonpapillary RCC patients and 200 healthy control subjects were analyzed using the TaqMan technique. The genotypic frequencies of the BCRP C421A polymorphism were compared between RCC patients and control subjects. The frequency of the C/C genotype was significantly higher in RCC patients than in control subjects (age- and gender-adjusted OR = 1.96, 95% CI 1.32-2.93). No associations were observed between the BCRP C421A polymorphism and clinicopathologic or epidemiologic factors, including age, gender, tumor grade, stage, cigarette smoking, family history of cancer and body mass index. Carriers with the C/C genotype of the BCRP C421A polymorphism are at risk of developing nonpapillary RCC. These data suggest that BCRP is a candidate RCC susceptibility gene.

Active and passive smoking and risk of renal cell carcinoma in Canada

This study aimed to assess the role of active and passive smoking in the development of renal cell carcinoma (RCC). Mailed questionnaires were completed by 1279 incident RCC cases and 5370 population controls between 1994 and 1997 in eight Canadian provinces. Data were collected on socio-economic status, smoking habits, diet and passive smoking status, as well as residential and occupational history. The study found an increased risk of RCC associated with active smoking. Elevated risk of RCC was also observed with passive smoking; compared with those never exposed to either passive or active smoking, men and women with 43 or more years of passive residential and/or occupational exposure had respective adjusted Odds Ratios (ORs) of 3.9 (95% Confidence Interval (CI) 1.4-10.6) and 1.8 (95% CI 1.0-3.3) (P=0.001 and P=0.09, respectively). Both active and passive smoking might play a role in the aetiology of RCC.

The inherent complexities of gene-environment interactions

The article outlines the complexities of gene-environment interactions in the determination of human disease, especially as they relate to aging, and stresses the importance of continuing such studies, in spite of their inherent difficulties. First, a capsule review of the literature pertaining to studies of gene-environment interactions is presented, and designs and methodologies used to detect these interactions are briefly discussed. Second, research questions and problems that can be addressed as outcomes of gene-environment interaction studies are exemplified. Third, a number of illustrative examples of gene-environment interactions are presented. Fourth, various types of gene-environment interactions are briefly discussed. Fifth, concluding remarks are offered, and possibilities of studying gene-environment interaction within social and biological research on aging are outlined.

Renal cell carcinoma in relation to cigarette smoking: meta-analysis of 24 studies

Renal cell carcinoma (RCC) accounts for 3% of adult deaths from cancer. The risk factors for its development are still under intense investigation. Although tobacco smoke is a risk factor, the data are inconsistent and the extent of the increased risk is unclear. Estimates from 19 case-control and 5 cohort studies were used. The case-control reports included 8,032 cases and 13,800 controls; the cohort estimates were based on 1,457,754 participants with 1,326 cases of RCC. The relative risk (RR) for RCC for ever smokers as compared to lifetime never smokers was 1.38 (95% confidence interval [CI] = 1.27-1.50). The RR for male smokers was 1.54 (95% CI = 1.42-1.68) and for female smokers was 1.22 (95% CI = 1.09-1.36). For men and women there was a strong dose-dependent increase in risk. Ever smoker men who had smoked 1-9, 10-20 or 21 or more cigarettes/day had a RR of 1.60 (95% CI = 1.21-2.12), 1.83 (95% CI = 1.30-2.57), or 2.03 (95% CI = 1.51-2.74), respectively. For women, the relative risks were 0.98 (95% CI = 0.71-1.35), 1.38 (95% CI = 0.90-2.11), or 1.58 (95% CI = 1.14-2.20), respectively. The advantages of smoking cessation were confirmed by a reduction in RR for those who had quit smoking for >10 years as compared to those who had quit for 1-10 years. Inhaled tobacco smoke is clearly implicated in the etiology of RCC, with a strong dose-dependent increase in risk associated with numbers of cigarettes smoked per day and a substantial reduction in risk for long-term former smokers.

Evaluation of the living kidney donor: current perspectives

Living kidney donation is increasing because of prolonged waiting times on the transplant list, as well as improved outcomes for recipients. In 2001, the number of living donors surpassed the number of deceased donors; this trend likely will continue with ever-increasing margins. Because of this increase, as well as changes in our society's health, it is time to re-review the guidelines for selecting living kidney donors established by Kasiske et al in 1995. A conference will be held this year to review updated literature on medical conditions that impact on renal health. From this, new guidelines for the medical evaluation of living renal donors will be constructed. This review discusses information known to date on the outcomes of individuals undergoing unilateral nephrectomy, the impact of lifestyle on renal function in the setting of nephrectomy, and advancements in the detection of genetically transmitted renal diseases that impact on today's decisions on living donation.

Does accounting for gene-environment (GxE) interaction increase the power to detect the effect of a gene in a multifactorial disease?

Despite tremendous efforts, few genes involved in the susceptibility for complex disorders have been identified. One explanation is that these disorders are a result of an interaction between genes and environment, and under such conditions, it may be difficult to measure the true genetic effect without accounting for the interaction. Umbach and Weinberg ([2000] Am. J. Hum. Genet. 66:251-261) proposed an association test which looks at the joint effects of genotype and environment, using case-parent trios. In this study, we explore under which conditions accounting for GxE interaction enhances one's ability to detect the role of genetic factors in complex diseases. Using asymptotic power calculations, we investigate the power to detect the gene effect over varying exposure frequencies and different scenarios of GxE interaction. We show that for a given sample size, interaction scenario, and allele frequency, the actual gain in power while accounting for the interaction depends on the magnitude of the exposure frequency: the largest gains are seen for relatively low exposure frequencies. Moreover, a loss of power can be observed when the exposure is frequent and/or the exposure effect is strong. If we consider a gene with a disease allele frequency of 0.2, with no effect in the absence of exposure, an exposure with a 10-fold increase risk and a GxE relative risk of 2, then when the exposure frequency is 0.1, accounting for GxE interaction increases the power to detect the gene effect in 200 trios by 10%; alternatively, when the exposure frequency is 0.9, it decreases the power by 15%.

Breast cancer risk and methylenetetrahydrofolate reductase polymorphism

OBJECTIVE

Methylenetetrahydrofolate reductase (MTHFR), a polymorphic enzyme involved in folate metabolism, plays a role in DNA biosynthesis, methylation, and repair in actively dividing cells. Because breast-cell division occurs in women with active ovulatory cycles, polymorphisms in the MTHFR gene could be a risk factor for breast cancer.

METHODS

We genotyped 352 clinic-based study subjects for MTHFR, 105 subjects with breast cancer and 247 with benign breast disease, histopathologically classified as high-risk or low-risk for breast cancer. Questionnaire data were collected prior to biopsy to blind subjects and interviewers to diagnoses.

RESULTS

Premenopausal women with the MTHFR polymorphism had a threefold increased breast cancer risk (OR = 2.8; 95%CI: 1.02-7.51) compared to the clinic-based controls with benign breast disease. Results were similar using either low- or high-risk controls. However, risk for postmenopausal women was not elevated (OR = 0.8; 95%CI 0.4-1.4). No significant interaction between genotype and smoking or alcohol was found, but polymorphic MTHFR decreased the likelihood of drinking alcohol (OR = 0.5; 95%CI 0.3-0.9).

CONCLUSION

These data suggest that polymorphic MTHFR increases risk of premenopausal, but not postmenopausal, breast cancer. These findings should be explored with a larger sample size in order to analyze gene-environment interactions between MTHFR and folate. Once the intricate relationship between diet and breast cancer has been elucidated, new cancer control initiatives can be considered such as folate chemoprevention trials in high-risk individuals.

The renal risks of smoking: an update

PURPOSE OF REVIEW

Smoking increases the renal risk both in diabetic and in nondiabetic renal disease. The purpose of the present review is to summarize the current state of knowledge about this important remediable renal risk factor.

RECENT FINDINGS

The deleterious effect of smoking on renal function extends beyond patients with primary or secondary renal disease and patients with a renal transplant, because recent studies document a relation between smoking and loss of filtration rate, even in cardiovascular high-risk populations without primary renal disease such as the elderly, the patient with severe essential hypertension, or the patient with widespread atherosclerosis. Furthermore, recent studies show that in nondiabetic patients without primary renal disease, albuminuria, a potential surrogate marker of glomerular damage, is correlated with smoking. The mechanisms underlying the adverse renal effects of smoking are still incompletely understood. Beyond its effect on progression of renal failure, smoking is also an important cardiovascular risk factor in the patient with renal failure or the patient with a renal transplant.

SUMMARY

Smoking is one of the most important remediable renal risk factors. The exact mechanisms of smoking-induced renal damage remain to be determined. For all the above reasons cessation of smoking should be recommended to renal patients - a recommendation which is infrequently given and even less frequently followed.

Differential gene expression in renal-cell cancer

Renal-cell carcinoma (RCC) is an important cause of morbidity and mortality, and its incidence has been increasing. Malignant transformation is thought to be associated with changes in the expression of several genes, and this alteration in gene expression is believed to be critical to the development of the malignant phenotype. In this study, the expression of about 60,000 genes/expressed sequence tags in clear-cell RCC, normal kidney, and a set of diseased nonmalignant kidneys was determined with the use of the Affymetrix microarray technique, and differences in gene expression were analyzed. Many genes were found to be differentially expressed in these two sample sets. The genes that were expressed greater than four times more in RCC, those expressed only in RCC, and those expressed greater than two times more in RCC and also expressed in a limited number of other tissues were analyzed for their expression in a variety of other normal and diseased tissues. Some of the genes identified were overexpressed only in RCC among the tissues examined, and some were overexpressed in several other malignant tissues in addition to RCC. Other genes were overexpressed in RCC compared with normal kidney but were also overexpressed in diseased nonmalignant kidney or a variety of other normal tissues. All of the RCC samples could be clustered together, separate from the normal and diseased kidney samples, with the use of the Eisen clustering technique and a set of 50 genes. The observed changes in gene expression in RCC should help further the understanding of the biology of RCC and may be useful in diagnosis, treatment, and imaging.