A Polymorphism in HDM2 (SNP309) Associates with Early Onset in Superficial Tumors, TP53 Mutations, and Poor Outcome in Invasive Bladder Cancer

Molecular Oncology of Bladder Cancer from Inception to Modern Perspective

Within the last forty years, seminal contributions have been made in the areas of bladder cancer (BC) biology, driver genes, molecular profiling, biomarkers, and therapeutic targets for improving personalized patient care. This overview includes seminal discoveries and advances in the molecular oncology of BC. Starting with the concept of divergent molecular pathways for the development of low- and high-grade bladder tumors, field cancerization versus clonality of bladder tumors, cancer driver genes/mutations, genetic polymorphisms, and bacillus Calmette-Guérin (BCG) as an early form of immunotherapy are some of the conceptual contributions towards improving patient care. Although beginning with a promise of predicting prognosis and individualizing treatments, "-omic" approaches and molecular subtypes have revealed the importance of BC stem cells, lineage plasticity, and intra-tumor heterogeneity as the next frontiers for realizing individualized patient care. Along with urine as the optimal non-invasive liquid biopsy, BC is at the forefront of the biomarker field. If the goal is to reduce the number of cystoscopies but not to replace them for monitoring recurrence and asymptomatic microscopic hematuria, a BC marker may reach clinical acceptance. As advances in the molecular oncology of BC continue, the next twenty-five years should significantly advance personalized care for BC patients.

The 40bp Indel Polymorphism rs150550023 in the MDM2 Promoter is Associated with Intriguing Shifts in Gene Expression in the p53-MDM2 Regulatory Hub

Most low-penetrance genetic risk factors for cancer are located in noncoding regions, presumably altering the regulation of neighboring genes. The poorly characterized Indel polymorphism rs150550023 (rs3730485; del1518) in the promoter of MDM2 (human homolog of mouse double minute 2) is a biologically plausible candidate genetic risk factor, which might influence the expression of MDM2, a key negative regulator of the central tumor suppressor p53. Here, we genotyped rs150550023 in a Central European hospital-based case-control study of 407 breast cancer patients and 254 female controls. mRNA levels of MDM2, p53, and the p53 target genes p21, BAX, and PERP were quantified with qRT-PCR, and p53 protein was assessed with immune histochemistry in ≈100 primary breast tumors with ascertained rs150550023 genotype. We found no evidence for an association of rs150550023 with the risk, age at onset, or prognosis of breast cancer. A possible synergism was observed with SNP309 in promoter P2 of MDM2. Mean mRNA levels of MDM2, p53, p21, and BAX were ≈1.5-3 fold elevated in TP53 wildtype tumors with the minor homozygous Del/Del genotype. However, systematic shifts in p53 protein levels or mutation rates were not observed, suggesting that the elevated p53 mRNA levels are due to regulatory feedback loops that compensate for the effects of rs150550023 on MDM2 expression.

Association of the MDM2 SNP285 and SNP309 Genetic Variants with the Risk, Age at Onset and Prognosis of Breast Cancer in Central European Women: A Hospital-Based Case-Control Study

SNP309T>G (rs2279744) and SNP285G>C (rs117039649) in the MDM2 promoter are thought to have opposite effects on the binding of transcription factor SP1 (specificity protein 1), and consequently on MDM2 expression, p53 levels, cancer risk, age at onset, and prognosis. Here, we genotyped SNP309 and SNP285 in 406 Austrian breast cancer patients and 254 female controls. The SNP309GG genotype was associated with an increased breast cancer risk in p53 negative (OR, 1.82; 95% CI, 1.09–3.03; p = 0.02), but not p53 positive or unselected patients. In contrast, the SNP309TT genotype was associated with an earlier age at onset (TT, 57.0 ± 12.9; TG, 58.6 ± 13.9; GG, 59.7 ± 15.0 years; p = 0.048). 31% of SNP309TT, 26% of TG, and 13% of GG tumors were p53 positive (p = 0.034), indicating a lower selective pressure to mutate TP53 in the presence of the G-allele. Moreover, SNP309TT patients exhibited a shortened metastasis-free survival in multivariable analysis. Censoring carriers of the SNP285C-allele hardly altered the strength of these associations of SNP309, thus challenging the proposed antagonistic function of SNP285C towards SNP309G. The minor SNP285C-allele tended to be non-significantly associated with an increased breast cancer risk and a poor disease-free and metastasis-free survival, which may be bystander effects of its complete linkage disequilibrium with SNP309G. We conclude that the SNP309G-allele attenuates the p53-response and leads to a higher breast cancer risk, but also to a later onset of breast cancer and a trend towards a good prognosis.

Association between MDM2 SNP309 and endometrial cancer risk: A PRISMA-compliant meta-analysis

BACKGROUND

Murine double minute 2 homolog (MDM2) plays an important role in the downregulation of P53 tumor suppressor gene. MDM2 inhibits P53 transcriptional activity and thereby results in accelerated tumor formation. Overexpression of MDM2 has been found in several cancer types including endometrial cancer. SNP309 is located in the promoter region of MDM2 and contributes to the overexpression of MDM2. The association between MDM2 SNP309 polymorphism and endometrial cancer risk has been investigated in several studies; however, the conclusion remains controversial.

OBJECTIVES

We performed the present meta-analysis to give a comprehensive conclusion of the association between MDM2 SNP309 polymorphism and endometrial cancer susceptibility.

METHODS

We conducted a literature research on PubMed, Embase, Cochrane Library, OVID, Web of Science, Wan Fang, CNKI, and CQVIP databases up to July 31, 2018. Newcastle-Ottawa scale was used to assess the quality of studies. We evaluated the strength of association by combining odds ratios (ORs) and 95% confidence intervals (CIs) in 5 different genetic models under a fixed-effect model or random-effect model. We further conducted subgroup analysis by ethnicity, source of control, histological type, clinical type, grade, and stage of tumor. Sensitivity analysis and publication bias were also performed.

RESULTS

Nine eligible studies were finally included in our meta-analysis. We found MDM2 SNP309 polymorphism increased the risk of endometrial cancer under allele model (OR: 1.23, 95% CI: 1.06-1.41, P = .005), homozygote model (OR: 1.43, 95% CI: 1.13-1.81, P = .003) and recessive model (OR: 1.55, 95% CI: 1.17-2.04, P = .002). Subgroup analysis suggested a similar elevated risk in both Asians and Caucasians. We identified a strong association of enhanced susceptibility to endometrial cancer in endometrioid group (OR: 2.13, 95% CI: 1.28-3.54, P = .004) and Type I group (OR: 1.89, 95% CI: 1.25-2.86, P = .002) under dominant model. We identified no significant publication bias according to Egger's test.

CONCLUSIONS

Our meta-analysis suggested that MDM2 SNP309 polymorphism increased the risk of endometrial cancer significantly, especially in endometrioid and Type I endometrial cancer, indicating MDM2 could serve as a potential diagnostic factor marker for endometrial cancer.

Association between MDM2-SNP309 and p53R72P polymorphisms and the risk of bladder cancer in the Mongolian population

The current study aims to investigate whether MDM2-SNP309 and p53R72P polymorphisms were associated with the risk of bladder cancer in Mongolian populations. These polymorphisms were evaluated in 79 controls and 63 bladder cancer cases using a PCR-restriction fragment length polymorphism assay, followed by analysis using multivariate logistic regression model and the Kaplan-Meier model to determine the odds ratio (OR) and age at onset of bladder cancer, respectively. The results revealed that the homozygous (G/G) genotype of MDM2-SNP309 increased the risk of bladder cancer compared to the wild-type (T/T) genotype [OR=1.629; 95% confidence interval (CI)=0.622-4.266] among Mongolians. On the other hand, the homozygous (P/P) genotype of p53R72P tended to protect the population from bladder cancer compared with the wild-type (R/R) genotype (OR=0.445; 95% CI=0.1727-2.147). It also showed that G/G genotype of MDM2-SNP309 increased the risk of bladder cancer when combined with the R/R genotype of p53R72P (OR=3.355; 95% CI=0.3914-28.766). Stratification by smoking and history of chronic urinary tract diseases tended towards increasing the risk association of the G/G (OR=2.3704; 95% CI=0.4308-3.044) and T/G genotypes (OR=5; 95% CI=0.8442-30.4088) of MDM2-SNP309 with bladder cancer, respectively. The protective role of P/P of p53R72P remained following stratification. MDM2-SNP309 and p53R72P were not involved in early age onset of bladder cancer in Mongolian patients. Taken together, MDM2-SNP309 and p53R72P had no significant association with bladder cancer in Mongolian patients. The two SNPs were also not able to predict early age at onset of bladder cancer.

Prognostic potential of the MDM2 309T>G polymorphism in stage I lung adenocarcinoma

The MDM2 protein plays an important role in the regulation of cell proliferation and apoptosis via ubiquitination and proteasome‐mediated degradation of p53. The genetic polymorphism rs2279744 (c.309T>G) of the MDM2 gene is reportedly associated with susceptibility and/or prognosis in various cancers. In this study, we investigated the risk factors for worse survival in patients with lung adenocarcinoma (AC). We examined the association between c.309T>G and the prognosis of lung cancer by retrospectively reviewing 453 lung cancer patients. We studied both, clinicopathological and genetic characteristics, including the c.309T>G, p53 Arg72Pro, EGFR,KRAS, and p53 mutations. Associations between these factors and survival outcome were analyzed using Cox proportional hazards models. The frequencies of MDM2 polymorphisms were T/T, 20.8%; T/G, 48.6%, and G/G, 30.7%. The overall survival (OS) of AC patients with pathological stage I disease and the MDM2 T/T genotype was significantly shorter than that of those with the T/G or G/G genotypes (P = 0.02). Multivariate analysis revealed that the MDM2 T/T genotype was an independent, significant prognostic factor (hazard ratio [HR] = 2.23; 95% confidence interval [CI]: 1.07–4.65; P = 0.03). The MDM2 T/T genotype was predictive of poorer survival in a Japanese population. Genotyping for this polymorphism might predict the clinical outcomes of stage I AC patients.

Murine Double Minute 2 SNP T309G Polymorphism and Urinary Tract Cancer Risk: A Meta-Analysis

Urinary tract cancer is a common cause of cancer-related death. The etiology and pathogenesis of urinary tract cancer remain unclear, with genetic and epigenetic factors playing an important role. Studies of the polymorphism of murine double minute 2 (MDM2) have shown inconclusive trends in the risk of urinary tract cancer.To clarify this inconsistency, we conducted updated meta-analyses to evaluate the role of MDM2 T309G polymorphism in urinary tract cancer susceptibility.Data sources were Pubmed (1966-May 2015), Chinese biomedicine literature database (1978-May 2015), and hand searching of the reference lists of included studies:(1) research categories case-control study or a nested case-control study; (2) information evaluating the association between the MDM2 SNP309 and urinary tract cancer risk; (3) studies with sufficient data to perform a meta-analysis.It included the use of odds ratios (ORs) to assess the strength of the association, and 95% confidence intervals (CIs) give a sense of the precision of the estimate. We used I for the assessment of between-study heterogeneity, and publication bias was assessed using the funnel plot and the Egger test. Statistical analyses were performed by Review Manage, version 5.0 and Stata 11.0.A total of 18 studies met the eligibility criteria and were included in our analyses. Overall, there was no statistical association between MDM2 SNP309 and prostate cancer risk for the allele contrast, the GG genotype, the recessive genetic model, the dominant genetic model, and prostate cancer risk in all subjects (OR = 0.96, 95% CI 0.87-1.05, P = 0.36; OR = 0.93, 95% CI 0.75-1.15, P = 0.50; OR = 1.00, 95% CI 0.87-1.15, P = 0.99; OR = 0.93, 95% CI 0.80-1.07, P = 0.30), and between MDM2 SNP309 and bladder cancer risk (the allele contrast: OR = 1.06, 95% CI 0.89-1.27, P = 0.50; the GG genotype: OR = 1.12, 95% CI 0.79-1.61, P = 0.52; the dominant genetic model: OR = 1.03, 95% CI 0.83-1.28, P = 0.78; the recessive genetic model: OR = 1.12, 95% CI 0.84-1.49, P = 0.45). However, there was positive association between MDM2 SNP309 and kidney cancer risk for the allele contrast (OR = 1.24, 95% CI 1.05-1.46, P = 0.01), the GG genotype (OR = 1.57, 95% CI 1.11-2.20, P = 0.01), dominant model contrast (OR = 1.30, 95% CI 1.00-1.68, P = 0.05), the recessive genetic model (OR = 1.37, 95% CI 1.02-1.83, P = 0.04).First, only the data of published studies were included in this meta-analysis. Unpublished studies tend to show more negative results; therefore, publication bias may be present. Second, because of the lack of the original data, we did not perform stratification analysis by age, hormone levels, dietary habit, or other variables. This might have caused confounding bias. Third, because the number of studies was relatively small for kidney cancer, the results might not have enough statistical power for us to investigate the association of the polymorphism with kidney cancer susceptibility, and we could not perform subgroup analyses. Finally, there were no studies about Africans in this meta-analysis.In summary, the results of our meta-analysis suggest an increased risk role of the MDM2 SNP T309G in renal cancer. However, there was no association between the MDM2 SNP T309G and prostate cancer risk or between the MDM2 SNP T309G and bladder cancer risk. Moreover, well-designed studies should estimate different ethnicities, degree of malignancy and clinical progression on the association between MDM2 SNP309 and urinary cancer risk in the future.

The T309G murine double minute 2 gene polymorphism is an independent prognostic factor for patients with renal cell carcinoma

The purpose of this study was to evaluate the association of the T309G MDM2 gene polymorphism with renal cell carcinoma (RCC) risk, pathology, and cancer-specific survival (CSS). T309G MDM2 was genotyped in 449 Caucasians, including 240 with RCC and 209 cancer-free controls. The T309G MDM2 genotype was TT in 174 (38.8%), GT in 214 (47.7%), and GG in 61 (13.6%) subjects, without any significant differences between cases and controls on both univariable (p=0.58) and multivariable logistic regression (each p>0.25). Furthermore, T309G MDM2 was not linked with T stage (p=0.75), N stage (p=0.37), M stage (p=0.94), grade (p=0.21), and subtype (p=0.55). There was, however, a statistically significant association of T309G MDM2 with CSS (p=0.022): patients with TT had significantly worse survival than GG/GT (p=0.009), while those with GT and GG had similar outcomes (p=0.92). The 5-year survival rate for patients with TT, GT, and GG was 69.5%, 84.5%, and 89.7%, respectively. On the multivariable analysis, T309G was identified as an independent prognostic factor. The T309G MDM2 polymorphism is an independent prognostic factor for patients with RCC, with the TT genotype being associated with worse prognosis. In this study, there were no significant associations with RCC risk and pathology.

Fibulin-1 is epigenetically down-regulated and related with bladder cancer recurrence

BACKGROUND

Bladder cancer is one of the most common cancers worldwide. Fibulin-1, a multi-functional extracellular matrix protein, has been demonstrated to be involved in many kinds of cancers, while its function in bladder cancer remains unclear. So here we investigated the expression and function of fibulin-1 in Bladder cancer.

METHODS

We used real-time PCR, Western blot analysis and immunohistochemistry to determine the expression of fibulin-1 in Bladder cancer cells and patient tissues respectively. Methylation-specific PCR and quantitative sequencing were used to examine the methylation status of FBLN1 gene promoter. Eukaryotic expression plasmid and lentiviral vector were used to overexpress fibulin-1 in Bladder cancer cells 5637, HT-1376 to investigate its function in vitro and in vivo.

RESULTS

We identified that fibulin-1 was significantly down-regulated in bladder cancer, and its dysregulation was associated with non-muscle-invasive bladder cancer (NMIBC) grade and recurrence. The promoter region of FBLN1 was generally methylated in bladder cancer cell lines and tissues, further investigation in patient tissues showed that the methylation status was associated with the fibulin-1 expression. Overexpression of fibulin-1 significantly suppressed tumor growth, induced tumor cell apoptosis, decreased cell motility, and inhibited angiogenesis in cultured bladder cancer cells and xenograft tumor in nude mice.

CONCLUSIONS

Altogether, our results indicated that fibulin-1 expression is associated with NMIBC grade and recurrence, it is epigenetically down-regulated and functions as a tumor suppressor gene and angiogenesis inhibitor in bladder cancer.

Significance of MDM2-309 polymorphisms and induced corresponding plasma MDM2 levels in susceptibility to laryngeal squamous cell carcinoma

The tumor suppressor p53 plays a crucial role in maintaining genomic stability and tumor prevention. Murine double-minute 2 (MDM2) oncoprotein plays a pivotal role in regulating p53, and the single-nucleotide polymorphism (SNP) 309T/G SNP in the promoter region of Mdm2 has been shown to be associated with increased risk of cancer. We investigated the association between Mdm2-309 promoter polymorphism, plasma MDM2 levels, and risk of laryngeal squamous cell carcinoma (LSCC). In this case-control study, 146 patients with LSCC, 61 patients with vocal leukoplakia, and 212 healthy controls were genotyped for the Mdm2-309 T/G gene using pyrosequencing. Plasma MDM2 levels were also analyzed by enzyme-linked immunosorbent assay (ELISA). Patients with LSCC had a significantly lower frequency of GT at Mdm2-309 (odds ratio [OR]=0.50, p=0.02) than controls. The proportion of GT heterozygotes in advanced stage cases were less than that in the initial stage patients (OR: 0.36 vs. 0.63; p=0.007 and 0.16). The same result was found between cases with and without lymph node metastases (OR: 0.45 vs. 0.52; p=0.075 and 0.04). Moreover, the plasma Mdm2 concentrations of LSCC patients (343.36±14.8 pg/mL) were significantly higher than those in controls (255.76±8.2 pg/mL; p<0.01) and vocal leukoplakia patients (301.42±8.6 pg/mL; p<0.05). Patients in advanced stages and with lymph node metastasis had higher plasma MDM2 levels, while the GT genotypes (308.06±18.9 pg/mL; p=0.037) had lower MDM2 plasma levels than the TT genotypes (369.00±25.2 pg/mL). The Mdm2 SNP309 G allele is implicated as an important LSCC and a vocal leukoplakia protective factor in the Chinese Han Population, and the proportion of GT genotype was lower in advanced LSCC patients and lymph node metastasis patients. Moreover, Mdm2-309 GT genotype patients had a lower plasma MDM2 level than the TT genotypes.

Prognostic value of cell-cycle regulation biomarkers in bladder cancer

The determination of prognosis in bladder cancer is currently based on staging methods that rely primarily on the pathological stage of a tumor with limited objective correlates. The development and progression of bladder cancer involve alterations in several cellular pathways. Dysregulation in markers associated with cell-cycle regulation has been the most extensively examined molecular aberration in this cancer. Individual alterations of these markers have been associated with disease outcome, with several observations suggesting that their prognostic potential is independent of pathological stage. While many individual molecules in the cell growth receptor signaling, p53, and retinoblastoma (Rb) pathways have been identified, there is a general lack of consensus on which markers can be adopted in the clinical setting. More recent studies have suggested that the combination of markers as concise panels may be more beneficial in determining the degree of aggressiveness of a given tumor and its impending outcome than individual markers alone. This review will discuss alterations in molecules within pathways controlling cell-cycle regulation in the context of bladder cancer, and their impact on patient outcome when examined individually and in combination.

Germline prognostic markers for urinary bladder cancer: obstacles and opportunities

Urinary bladder cancer is a heterogeneous disease with diverse genetic and environmental risk factors that can influence disease risk or clinical course for recurrence, progression, and survival. Therefore, identification of these factors is paramount for disease prevention and optimal clinical management of bladder cancer patients. Of particular interest is the need to identify molecular biomarkers that can give accurate assessment of tumor biological potential and to predict treatment response. Recent advances in molecular biology, cytogenetic, and genomic research have spurred discovery efforts for novel genetic, epigenetic, and proteomic biomarkers that are prognostic for cancer. This review focuses on some of the important germ line polymorphisms found to be correlated with clinical outcomes in bladder cancer. So far, most of the identified candidate loci were based on prior knowledge of pathogenesis and had not been validated for clinical applications. The future challenges are to analyze the wealth of information from whole-genome studies, to understand the underlying biological mechanisms of these associations, the network of gene-gene and gene-environment interactions, and to apply these markers for the identification of high-risk population for targeted, personalized therapy.

Influence of MDM2 and MDM4 on development and survival in hereditary retinoblastoma

BACKGROUND

Retinoblastoma (RB) accounts for 3% of all childhood malignancies, with different incidences around the world. This malignancy results from loss-of-function of both RB1 alleles although other genes, like MDM2 and MDM4, have been proposed to be involved in tumor development.

PROCEDURE

We genotyped rs2279744T>G and rs937283A>G in MDM2, and rs4252668T>C and rs116197192G>A in MDM4, in 104 unrelated RB patients and 104 controls. Sixty-month survival Kaplan-Meier curves and χ(2)-tests were performed for estimating the putative effect of MDM2 and MDM4 alleles on disease progression and survival of RB patients.

RESULTS

MDM2 rs2279744G was significantly more frequent in controls, indicating an apparently protective effect on RB development. However, survival of patients who carried a constitutional RB1 mutation was significantly lower with rs2279744TG or GG than with rs2279744TT. Presence of rs2279744G and a constitutional RB1 mutation was sixfold more frequent in the 0-12 month age group than other age groups at onset of symptoms (P = 0.0401). MDM4 rs4252668C was present at a significantly higher frequency in controls while the frequency of MDM4 rs116197192G was significantly higher in RB patients, suggesting that this allele might increase the risk of developing RB.

CONCLUSION

Our results indicate that MDM2 and MDM4 polymorphisms may influence development and/or survival in RB.

Nuclear localization of COX-2 in relation to the expression of stemness markers in urinary bladder cancer

Inflammation may activate stem cells via prostaglandin E2 (PGE2) production mediated by cyclooxygenase-2 (COX-2) expression. We performed an immunohistochemical analysis of the expression of stemness markers (Oct3/4 and CD44v6) and COX-2 in urinary bladder tissues obtained from cystitis and cancer patients with and without Schistosoma haematobium infections. Immunoreactivity to Oct3/4 was significantly higher in S. haematobium-associated cystitis and cancer tissues than in normal tissues. CD44v6 expression was significantly higher in bladder cancer without S. haematobium than in normal tissues. COX-2 was located in the cytoplasmic membrane, cytoplasm, and nucleus of the cancer cells. Interestingly, the nuclear localization of COX-2, which was reported to function as a transcription factor, was significantly associated with the upregulation of Oct3/4 and CD44v6 in bladder cancer tissues with and without S. haematobium infection, respectively. COX-2 activation may be involved in inflammation-mediated stem cell proliferation/differentiation in urinary bladder carcinogenesis.

Multiple Interactions between Peroxisome Proliferators-Activated Receptors and the Ubiquitin-Proteasome System and Implications for Cancer Pathogenesis

The peroxisome proliferator-activated receptors (PPAR) α, β/δ, and γ are ligand-activated nuclear receptors involved in a number of physiological processes, including lipid and glucose homeostasis, inflammation, cell growth, differentiation, and death. PPAR agonists are used in the treatment of human diseases, like type 2 diabetes and dyslipidemia, and PPARs appear as promising therapeutic targets in other conditions, including cancer. A better understanding of the functions and regulation of PPARs in normal and pathological processes is of primary importance to devise appropriate therapeutic strategies. The ubiquitin-proteasome system (UPS) plays an important role in controlling level and activity of many nuclear receptors and transcription factors. PPARs are subjected to UPS-dependent regulation. Interestingly, the three PPAR isotypes are differentially regulated by the UPS in response to ligand-dependent activation, a phenomenon that may be intrinsically connected to their distinct cellular functions and behaviors. In addition to their effects ongene expression, PPARs appear to affect protein levels and downstream pathways also by modulating the activity of the UPS in target-specific manners. Here we review the current knowledge of the interactions between the UPS and PPARs in light of the potential implications for their effects on cell fate and tumorigenesis.

Expression profiling for bladder cancer: strategies to uncover prognostic factors

Despite being a common cancer worldwide, management of transitional cell carcinoma of the bladder currently relies primarily on clinical staging and histopathologic parameters. Assaying alterations in molecular pathways can contribute valuable information that can accurately predict outcome and chemotherapeutic response in individual patients with bladder cancer. Medium- to high-throughput gene-expression profiling technologies are now allowing multiplexed assessment of alterations responsible for the genesis and progression of bladder tumors. These investigations employ global or pathway-based approaches to define molecular signatures that can predict prognosis independent of traditional clinical performance metrics. Prognostic panels generated using these strategies can also elucidate the biology of tumor progression and identify potential therapeutic targets.

MDM2 SNP309 is associated with endometrial cancer susceptibility: a meta-analysis

Epidemiological studies have investigated the association between MDM2 promoter SNP 309 (T/G) and endometrial cancer susceptibility. However, the results are still controversial. To obtain a more precise estimate of the relationship, we conducted a meta-analysis of 1,001 cases and 1,889 controls from 6 published case-control studies (one of five articles contains two studies) to estimate the effect of SNP309 on endometrial cancer risk. The strength of association between MDM2 SNP309 and endometrial cancer susceptibility was assessed by calculating pooled odds ratios (ORs) with 95% confidence intervals (CIs). When all the eligible studies were pooled in the meta-analysis, we found that elevated endometrial cancer risk was significantly associated with GG variant genotype, however, heterozygous genotype TG seemed to be only a minor modifier on endometrial cancer risk (for GG vs. TT, OR = 1.54, 95% CI = 1.21-1.95, P = 0.0004; for TG vs. TT, OR = 0.96, 95% CI = 0.81-1.14, P = 0.66; for dominant model, OR = 1.09, 95% CI = 0.93-1.29, P = 0.29; for recessive model, OR = 1.65, 95% CI = 1.33-2.04, P < 0.00001). Overall, the meta-analysis suggested that the GG genotype of MDM2 SNP309 was significantly associated with the increased endometrial cancer risk.

Bladder cancer or bladder cancers? Genetically distinct malignant conditions of the urothelium

Despite the fact that the current histopathologic classification for bladder cancer has led to improved concepts for the clinical management of the disease, key questions with regard to assessment of risk for recurrence and/or progression to invasive disease remain. In addition, response to specific therapies cannot be predicted accurately. Bladder tumors comprise a heterogeneous group with respect to both histopathology and clinical behavior. Thus, it is anticipated that a thorough knowledge and interpretation of the molecular alterations involved in tumor development and progression will lead to greater prognostic and predictive power. This may not only lead to better comprehension of the biology of the disease, but may also lead to the development of novel individualized therapies. Novel means of stratification are urgently needed to provide a new subclassification of urothelial lesions. This review discusses and summarizes the genetic alterations that have been reported in bladder cancer and relates these to the current 2-pathway model for tumor development. The molecular pathogenesis of high-grade noninvasive papillary tumors and of T1 tumors is not yet clear, and possibilities are discussed.

Single-nucleotide polymorphisms in the p53 signaling pathway

The p53 tumor suppressor pathway is central both in reducing cancer frequency in vertebrates and in mediating the response of commonly used cancer therapies. This article aims to summarize and discuss a large body of evidence suggesting that the p53 pathway harbors functional inherited single-nucleotide polymorphisms (SNPs) that affect p53 signaling in cells, resulting in differences in cancer risk and clinical outcome in humans. The insights gained through these studies into how the functional p53 pathway SNPs could help in the tailoring of cancer therapies to the individual are discussed. Moreover, recent work is discussed that suggests that many more functional p53 pathway SNPs are yet to be fully characterized and that a thorough analysis of the functional human genetics of this important tumor suppressor pathway is required.

Strategies for molecular expression profiling in bladder cancer

Carcinoma of the urinary bladder involves alterations in multiple cellular pathways that dictate the pathology of the disease and clinical outcome of the patient. This includes alterations in regulation of the cell cycle, apoptotic mechanisms, signal transduction and tumor angiogenesis. Interrogation of alterations in multiple molecules associated with these pathways is leading to the development of biomarker panels that are capable of predicting an individual patient's outcome or response to specific treatments. With respect to gene expression profiling, two broad approaches may be identified: a global approach and a pathway-specific approach. The global approach involves a high-throughput effort to profile the entire genome, while the pathway-specific approach quantifies select genes across several pathways. While the former has a high potential for discovery of novel signatures, the latter is important in generating reproducible and concise panels that have the potential for rapid clinical implementation. A combination of both these approaches is needed for the identification and validation of robust marker panels of potential clinical importance in bladder cancer.

Germline mutations and polymorphisms in the origins of cancers in women

Several female malignancies including breast, ovarian, and endometrial cancers can be characterized based on known somatic and germline mutations. Initiation and propagation of tumors reflect underlying genomic alterations such as mutations, polymorphisms, and copy number variations found in genes of multiple cellular pathways. The contributions of any single genetic variation or mutation in a population depend on its frequency and penetrance as well as tissue-specific functionality. Genome wide association studies, fluorescence in situ hybridization, comparative genomic hybridization, and candidate gene studies have enumerated genetic contributors to cancers in women. These include p53, BRCA1, BRCA2, STK11, PTEN, CHEK2, ATM, BRIP1, PALB2, FGFR2, TGFB1, MDM2, MDM4 as well as several other chromosomal loci. Based on the heterogeneity within a specific tumor type, a combination of genomic alterations defines the cancer subtype, biologic behavior, and in some cases, response to therapeutics. Consideration of tumor heterogeneity is therefore important in the critical analysis of gene associations in cancer.

Association of TP53 and MDM2 polymorphisms with survival in bladder cancer patients treated with chemoradiotherapy

Platinum-based chemoradiotherapy (CRT) as bladder conservation therapy has shown promising results for muscle-invasive bladder cancer. However, CRT might diminish survival as a result of the delay in cystectomy for some patients with non-responding bladder tumors. Because the p53 tumor suppression pathway, including its MDM2 counterpart, is important in chemotherapy- and radiotherapy-associated effects, functional polymorphisms in the TP53 and MDM2 genes could influence the response to treatment and the prognosis following CRT. We investigated associations between two such polymorphisms, and p53 overexpression, and response or survival in bladder cancer patients treated with CRT. The study group comprised 96 patients who underwent CRT for transitional cell carcinoma of the bladder. Single nucleotide polymorphisms (SNPs) in TP53 (codon 72, arginine > proline) and MDM2 (SNP309, T > G) were genotyped using PCR-RFLP, and nuclear expression levels of p53 were examined using immunohistochemistry. None of the genotypes or p53 overexpression was significantly associated with response to CRT. However, patients with MDM2 T / G + G / G genotypes had improved cancer-specific survival rates after CRT (P = 0.009). In multivariate analysis, the MDM2 T / G + G / G genotypes, and more than two of total variant alleles in TP53 and MDM2, were independently associated with improved cancer-specific survival (P = 0.031 and P = 0.015, respectively). In addition, MDM2 genotypes were significantly associated with cystectomy-free survival (P = 0.030). These results suggest that the TP53 and MDM2 genotypes might be useful prognostic factors following CRT in bladder cancer, helping patient selection for bladder conservation therapy.

Mdm2 Snp309 G allele displays high frequency and inverse correlation with somatic P53 mutations in hepatocellular carcinoma

Loss of function of the p53 protein, which may occur through a range of molecular events, is critical in hepatocellular carcinoma (HCC) evolution. MDM2, an oncogene, acts as a major regulator of the p53 protein. A polymorphism in the MDM2 promoter, SNP309 (T/G), has been shown to alter protein expression and may thus play a role in carcinogenesis. MDM2 SNP309 is also associated with HCC. However, the role of SNP309 in hepatocarcinogenesis with respect to TP53 mutations is unknown. In this study, we investigated the distribution of the MDM2 SNP309 genotype and somatic TP53 (the p53 tumor suppressor gene) mutations in 99 human HCC samples from Africa, Europe, China and Japan. Samples exhibited striking geographical differences in their distribution of SNP309 genotypes. The frequency and spectrum of p53 mutations also varied geographically; TP53 mutations were frequent in Africa, where the SNP309 T/T genotype predominated but were rare in Europe and Japan, where the SNP309 G allele was present more frequently. TP53 mutations were detected in 18% (4/22) of SNP309 T/G and G/G and 82% (18/22) of SNP309 T/T genotype holders; this difference was statistically highly significant (P-value=0.0006). Our results indicated that the presence of the SNP309 G allele is inversely associated with the presence of somatic TP53 mutations because they only coincided in 4% of HCC cases. This finding suggests that the SNP309 G allele may functionally replace p53 mutations, and in addition to known etiological factors, may be partly responsible for differential HCC prevalence.

Recent natural selection identifies a genetic variant in a regulatory subunit of protein phosphatase 2A that associates with altered cancer risk and survival

PURPOSE

A regulated p53-dependent stress response is crucial in suppressing tumor formation and mediating the response to commonly used cancer therapeutics. However, little is known about the human, inherited genetics of this important signaling pathway.

EXPERIMENTAL DESIGN

Studies of human genetic variants in the p53 tumor suppressor gene and MDM2 oncogene have shown that single nucleotide polymorphisms (SNP) can affect p53 signaling, confer cancer risk, and alter outcome, and also suggest that the pathway is under evolutionary selective pressure. Here, we attempt to accelerate the identification of functional p53 pathway SNPs by incorporating these characteristics into an analysis of 142 genes that are known to affect p53 signaling.

RESULTS

We report that a genomic scan for recent natural selection denotes that of the 142 genes studied, the PPP2R5E gene that encodes a regulatory subunit of the tumor suppressing protein phosphatase 2A resides in a naturally selected genomic region. We go on to show that a selected SNP in PPP2R5E (epsilon-SNP2) associates with significant allelic differences in the onset (up to 19.2 years; P = 0.0002) and risk (odds ratio, up to 8.1; P = 0.0009) of soft tissue sarcoma development, as well as overall survival (relative risk, up to 3.04; P = 0.026).

CONCLUSIONS

The PPP2R5E gene is identified as harboring genetic variants that can affect human cancer and are possibly under evolutionary selection pressure.

Effect of TP53 Arg72Pro and MDM2 SNP309 polymorphisms on the risk of high-grade osteosarcoma development and survival

PURPOSE

The germ-line polymorphisms TP53 Arg72Pro and MDM2 SNP309 T>G are risk factors for tumor development and affect response to chemotherapy and survival in several cancers, but their prognostic and predictive value in patients with high-grade osteosarcomas is not yet defined. The purpose of this study was to investigate the effect of the TP53 Arg72Pro and the MDM2 SNP309 on the risk of osteosarcoma development and survival.

EXPERIMENTAL DESIGN

The relative risk to develop osteosarcomas and the overall survival associated to TP53 Arg72Pro and MDM2 SNP309 polymorphisms were investigated in 201 patients. Correlations with event-free survival (EFS) were analyzed in a homogeneous subgroup of 130 patients with high-grade osteosarcomas of the limbs, nonmetastatic at diagnosis, which underwent neoadjuvant chemotherapy.

RESULTS

Multivariate analysis showed that the MDM2 polymorphism T309G was associated with an increased risk of developing osteosarcomas [GG versus TT; odds ratio, 2.09; 95% confidence interval (95% CI), 1.15-3.78]. A case/control gender approach evidenced a significant increased risk only for female osteosarcoma patients (GG versus TT; odds ratio, 4.26; 95% CI, 1.61-11.25). Subjects carrying the TP53 Arg72Pro polymorphism were found to have a significantly increased death risk (Pro/Pro versus Arg/Arg; hazard ratio, 2.90; 95% CI, 1.28-6.66). In the subgroup of 130 high-grade osteosarcomas, the TP53 Arg72Pro was an independent marker of EFS (Pro/Pro versus Arg/Arg; hazard ratio, 2.67; 95% CI, 1.17-6.11).

CONCLUSION

The study provides evidence supporting the association of MDM2 SNP309 with high-grade osteosarcoma risk in females and shows that TP53 Arg72Pro has a prognostic value for overall survival and EFS in osteosarcoma patients.

Altered tumor formation and evolutionary selection of genetic variants in the human MDM4 oncogene

A large body of evidence strongly suggests that the p53 tumor suppressor pathway is central in reducing cancer frequency in vertebrates. The protein product of the haploinsufficient mouse double minute 2 (MDM2) oncogene binds to and inhibits the p53 protein. Recent studies of human genetic variants in p53 and MDM2 have shown that single nucleotide polymorphisms (SNPs) can affect p53 signaling, confer cancer risk, and suggest that the pathway is under evolutionary selective pressure (1-4). In this report, we analyze the haplotype structure of MDM4, a structural homolog of MDM2, in several different human populations. Unusual patterns of linkage disequilibrium (LD) in the haplotype distribution of MDM4 indicate the presence of candidate SNPs that may also modify the efficacy of the p53 pathway. Association studies in 5 different patient populations reveal that these SNPs in MDM4 confer an increased risk for, or early onset of, human breast and ovarian cancers in Ashkenazi Jewish and European cohorts, respectively. This report not only implicates MDM4 as a key regulator of tumorigenesis in the human breast and ovary, but also exploits for the first time evolutionary driven linkage disequilibrium as a means to select SNPs of p53 pathway genes that might be clinically relevant.

Molecular pathogenesis and diagnostics of bladder cancer

Despite elaborate characterization of the risk factors, bladder cancer is still a major epidemiological problem whose incidence continues to rise each year. Urothelial carcinoma is now recognized as a disease of alterations in several cellular processes. The more prevalent, less aggressive, recurrent, noninvasive tumors are characterized by constitutive activation of the Ras-MAPK pathway. The less common but more aggressive invasive tumors, which have a higher mortality rate, are characterized by alterations in the p53 and retinoblastoma pathways. Several diagnostic tests have attempted to identify these molecular alterations in tumor cells exfoliated in the urine, whereas prognostic tests have tried to identify aberrations so as to predict tumor behavior and identify therapeutic targets. The future of bladder cancer patient management will rely on the use of molecular tests to reliably diagnose the presence of disease, predict individual tumor behavior, and suggest potential targeted therapeutics.

A six-nucleotide insertion-deletion polymorphism in the CASP8 promoter associated with risk and progression of bladder cancer

PURPOSE

Caspase-8 (CASP8) is a key regulator of apoptosis or programmed cell death, an essential defense mechanism against hyperproliferation and malignancy. We hypothesized that the variants in the CASP8 gene are associated with risk of bladder cancer.

EXPERIMENTAL DESIGN

In a hospital-based case-control study of 365 case patients with newly diagnosed bladder transitional cell carcinoma and 368 cancer-free controls frequency-matched by age and sex, we genotyped the functional -652 6N ins/del polymorphism (rs3834129) in the promoter of CASP8 and assessed its associations with risk of bladder cancer and interaction with tobacco smoking.

RESULTS

A significant decreased risk of bladder cancer was found for the CASP8 -652 6N ins/del (adjusted odds ratio, 0.72; 95% confidence interval, 0.53-0.99) and del/del (odds ratio, 0.37; 95% confidence interval, 0.18-0.77) genotypes. Furthermore, a significant additive interaction between CASP8 polymorphism and tobacco smoking on bladder cancer risk was observed.

CONCLUSIONS

These results suggested that the CASP8 -652 6N ins/del polymorphism is involved in etiology of bladder cancer and thus may be a marker for genetic susceptibility to bladder cancer in Chinese populations. Larger studies are warranted to validate our findings.

Molecular alterations associated with bladder cancer initiation and progression

Bladder cancer is the fifth most commonly diagnosed non-cutaneous solid malignancy, and the second most commonly diagnosed genitourinary malignancy amongst people living in the United States, where it is estimated that more than 61,000 new cases of bladder cancer will be diagnosed in the year 2008. Approximately 90% of malignant tumors arising in the urinary bladder are of epithelial origin, the majority being transitional cell carcinomas. Early stage bladder tumors have been classified into two groups with distinct behavior and unique molecular profiles: low grade tumors (always papillary and usually superficial), and high-grade tumors (either papillary or non-papillary, and often invasive). Clinically, superficial bladder tumors (stages Ta and Tis) account for 75% to 85% of neoplasms, while the remaining 15% to 25% are invasive (T1, T2-T4) or metastatic lesions at the time of initial presentation. Studies from the author's group and others have revealed that distinct genotypic and phenotypic patterns are associated with early versus late stages of bladder cancer. Most importantly, early superficial diseases appear to segregate into two main pathways. Superficial papillary bladder tumors are characterized by gain-of-function mutations, mainly affecting classical oncogenes such as RAS and FGFR3. Deletions of chromosome 9, mainly allelic losses on the long arm (9q) are also frequent events in these tumors. Such genetic alterations are observed in most if not all superficial papillary non-invasive tumors (Ta), but only in a small subset of invasive bladder neoplasms. Flat carcinoma in situ (Tis) and invasive tumors are characterized by loss-of-function mutations, affecting the prototype tumor suppressor genes, including p53, RB and PTEN. These alterations are absent or very rare in the Ta tumors analyzed, but have been frequently identified in invasive bladder carcinomas. Based on these data, a novel model for bladder tumor progression has been proposed in which two separate genetic pathways characterize the evolution of superficial bladder neoplasms. Numerous individual molecular markers have been identified in the tissue specimens that correlate to some extent with tumor stage, and possibly with prognosis in bladder cancer. However, these molecular prognosticators do not play a role in the clinical routine management of patients with bladder tumors, mainly due to lack of large prospective validation studies. Thus, the need for development of specific tissue and serum tumor markers for prognostic stratification remains. The advent of high-throughput microarrays technologies allows comprehensive discovery of targets relevant in bladder cancer progression, which could be translated into new approaches for drug and biomarker development. Further investigation is warranted to define novel biomarkers specific for bladder cancer patients based on the molecular alterations of tumor progression, and multiplexed strategies for clinical management.

Genetic epidemiology of bladder cancer: scaling up in the identification of low-penetrance genetic markers of bladder cancer risk and progression

Bladder cancer is an increasingly important international public health problem. As a multifactorial disease, both environmental and genetic factors are involved in its development and progression. This neoplasm is a paradigm for the participation of low-penetrance genetic variants (GSTM1-null and NAT2-slow) and provides the best established gene-environment interaction in cancer (NAT2-slow * tobacco). Genetic variants in nucleotide excision and double strand break DNA repair pathways have provided promising results, ERCC2-XPD rs238406 being the most consistent variant associated with an increased of bladder cancer risk, by itself and by interacting with tobacco. Variants in other pathways such as cell-cycle control, 1-C metabolism and inflammation have been studied, although the results are inconsistent. Three very large whole genome association studies are being undertaken using the same genotyping platform. Their results will be available soon. Genetic variants have seldom been considered as markers of prognosis or response to therapy in this tumour. The results of these studies are inconclusive. Other issues that need to be addressed are the role of genetic variants in different population subgroups--defined by ethnicity, gender and age, among others--and the association with bladder cancer subphenotypes according to clinical, pathological and molecular characteristics of the tumour. This endeavour can only be achieved by integrating multidisciplinary tools and information. Can this information be applied better to identify high-risk populations? Can the information be used to better assess prognosis or predict response to therapy? These questions require large, well-designed, multicentre studies to be conducted. Funding agencies should be aware of these needs.

Association of HDM2 transcript levels with age of onset and prognosis in soft tissue sarcomas

The p53 stress response is crucial for the prevention of tumor formation. The oncogene HDM2 is one of the key negative regulators of p53 and is a central node in the p53 pathway. P53 and HDM2 form an oscillating feedback loop. HDM2 expression is regulated by different promoters. To evaluate its clinical relevance, we determined the levels of HDM2 transcripts originating from the constitutive P1 and p53-sensitive P2 promoter in 133 soft tissue sarcomas and correlated the results with the age of diagnosis and the patients' outcome. We show that only high levels of the HDM2-P1 transcript but not the P2 transcript are associated with an 11-year earlier age of onset (50.5 years) compared with low P1 levels (61.5 years; P < 0.0001, t test). In addition, low P1 and P2 mRNA expression levels were independent predictors of poor outcome for patients with soft tissue sarcomas (low P1: relative risk, 3.7; P < 0.0001; low P2: relative risk, 2.5; P = 0.001). A change in the expression levels of the HDM2 transcripts originating from the two HDM2 promoters could disrupt the oscillating P53-HDM2 feedback loop in a way that elevated levels of HDM2-P1 transcript are associated with an earlier age of tumor onset and that reduced levels of HDM2-P1 or HDM2-P2 transcripts are correlated with poor prognosis of patients with soft tissue sarcomas.

MDM2 SNP309 is associated with high grade node positive breast tumours and is in linkage disequilibrium with a novel MDM2 intron 1 polymorphism

INTRODUCTION

A functional polymorphism within MDM2, SNP309 T>G, has been linked to early onset cancer. This study examined clinical associations of breast cancer with SNP309 in a Scottish Caucasian population and investigated additional MDM2 intron 1 polymorphisms.

METHODS

Intron 1 of MDM2 was PCR amplified and directly sequenced from 299 breast cancer patients and 275 cancer free controls and compared with clinical and pathological parameters.

RESULTS

SNP309 was observed, for the control and breast cancer cohorts respectively, at frequencies of: T/T = 44.7% and 39.5%; G/T = 42.2% and 47.2%; G/G = 13.1% and 13.4%, indicating that SNP309 is not a predisposing factor for breast cancer. The 309G/G genotype was associated with high grade tumours (OR = 1.64, 95%CI = 1.06-2.53, p = 0.025) and greater nodal involvement (OR = 2.51, 95%CI = 1.26-4.98, p = 0.009). SNP309 was not associated with an earlier age of cancer diagnosis. No association was observed between genotype and age of breast cancer diagnosis when patients were stratified by menopausal status and estrogen receptor status. Three additional low frequency SNPs were identified: 344T>A, 285G>C and 443G>T, the latter two novel. SNP285 was in complete linkage disequilibrium with SNP309 (D' = 1.0) with the minor alleles being in phase with each other. Moreover, the 285C/C, 309G/G double homozygous genotype was only observed in the breast cancer cohort.

CONCLUSION

SNP309G/G is associated with poor prognostic breast cancer features in the Scottish population. Additionally, a novel SNP, SNP285, that is in linkage disequilibrium with SNP309, may also have a role in breast tumorigenesis.

p53-independent mechanisms regulate the P2-MDM2 promoter in adult astrocytic tumours

The MDM2 gene is amplified and/or overexpressed in about 10% of glioblastomas and constitutes one of a number of ways the p53 pathway is disrupted in these tumours. MDM2 encodes a nuclear phosphoprotein that regulates several cell proteins by binding and/or ubiquitinating them, with p53 being a well-established partner. MDM2 has two promoters, P1 and P2 that give rise to transcripts with distinct 5′ untranslated regions. Transcription from P2 is believed to be controlled by p53 and a single-nucleotide polymorphism (SNP309, T>G) in P2 is reported to be associated with increased risk for, and early development of, malignancies. The use of P1 and P2 has not been investigated in gliomas. We used RT–PCR to study P1- and P2-MDM2 transcript expression in astrocytic tumours, xenografts and cell lines with known MDM2, TP53 and p14^ARF gene status. Both promoters were used in all genetic backgrounds including the use of the P2 promoter in TP53 null cells, indicating a p53-independent induction of transcription. Transcripts from the P1 promoter formed a greater proportion of the total MDM2 transcripts in tumours with MDM2 amplification, despite these tumours having two wild-type TP53 alleles. Examination of SNP309 in glioblastoma patients showed a borderline association with survival but no apparent correlation with age at diagnosis nor with TP53 and p14^ARF status of their tumours. Our findings also indicate that elevated MDM2 mRNA levels in tumours with MDM2 amplification are preferentially driven by the P1 promoter and that the P2 promoter is not only regulated by p53 but also by other transcription factor(s).

A novel functional polymorphism C1797G in the MDM2 promoter is associated with risk of bladder cancer in a Chinese population

PURPOSE

MDM2 is believed to regulate the p53 level in modulating DNA repair, cell cycle control, cell growth, and apoptosis. We hypothesize that genetic variants in the MDM2 gene are associated with risk of bladder cancer.

EXPERIMENTAL DESIGN

We first conducted a case-control study of 234 bladder cancer cases and 253 cancer-free controls, using the haplotype-based tagging single nucleotide polymorphism (SNP) approach involving 13 common SNPs initially identified in 100 control subjects. We then examined the functionality of the important SNP.

RESULTS

We found that the C1797G polymorphism in the MDM2 promoter region is an important SNP because its homozygous variant genotype, but none of the haplotypes, was associated with risk of bladder cancer. Electrophoretic mobility shift assay indicated that the 1797C to 1797G transition within the CAAT/enhancer binding protein alpha (C/EBP alpha) core sequence greatly enhanced the C/EBP alpha binding affinity to the promoter region. The in vitro luciferase assays in various cell lines further showed an increased transcriptional activity of the 1797G allele compared with the 1797C allele. Additional experiments with tumor tissues revealed that the transcriptional activator C/EBP alpha containing the 1797G allele increased levels of the MDM2 mRNA and protein in bladder tumor tissues.

CONCLUSIONS

These data suggested that the novel MDM2 promoter C1797G polymorphism may affect the MDM2 activity by altering the C/EBP alpha binding affinity to the promoter and, thus, may be a marker for genetic susceptibility to bladder cancer in Chinese populations. Further validation of the functionality of the MDM2 C1797G polymorphism and its association with risk of bladder and other cancers in other ethnic populations is warranted.

Impact of MDM2 single nucleotide polymorphism on tumor onset in head and neck squamous cell carcinoma

CONCLUSIONS

The GG genotype of MDM2 SNP309 is associated with an earlier onset of head and neck squamous cell carcinoma (HNSCC) in the Japanese population. SNP309 may be a key factor in the tumorigenesis of HNSCC as well as other hereditary or sporadic tumors.

OBJECTIVE

This study was designed to evaluate the association between the single nucleotide polymorphism (SNP) 309 in the MDM2 gene with HNSCC. An MDM2 protein down-regulates the p53 pathway. Recently, an important SNP was discovered in the MDM2 promoter region, which could affect the tumorigenesis of HNSCC by attenuation of the p53 pathway.

PATIENTS AND METHODS

Patients with 103 HNSCCs were genotyped using direct sequencing and real-time PCR. The relationship between the SNP309 genotypes and the clinicopathological features was statistically analyzed.

RESULTS

The number of patients genotyped to TT, TG, and GG was 29 (28%), 46 (44.7%), and 28 (27.2%), respectively. The average age at tumor onset was 65.6 years for TT, 62.9 years for TG, and 56.7 years for GG. The patients with the GG genotype had a significantly earlier tumor onset in comparison to those with the TT genotype (p=0.032).

Mdm2-SNP309 polymorphism in prostate cancer: no evidence for association with increased risk or histopathological tumour characteristics

The search for inherited cancer susceptibility factors is a major focus of epidemiologic cancer studies. Analyses of single-nucleotide polymorphisms (SNP) in a variety of genes revealed a correlation between a specific allele variant and cancer predisposition. Human mouse double-minute 2 protein (Mdm2) is a cellular E3 ligase capable of ubiquitination and degradation of p53. Therefore, Mdm2 is a crucial factor of cell cycle control and cell survival. The Mdm2 promoter SNP309 was shown to increase Mdm2 expression and can, thereby, inhibit the p53 pathway. This SNP was found to be associated with increased risk and early onset of various malignancies. For prostate cancer no studies are reported to date. In a case-control study we determined the distribution of the Mdm2 SNP309 in 145 male subjects with prostate cancer and in 124 male controls without any malignancy using RFLP analysis. Cases and controls showed a similar distribution of the SNP (P=0.299). Genotype distribution showed neither an association with histopathological characteristics of the tumours nor with prognosis. Age at disease onset was also not modified by the SNP. This first study of the Mdm2 SNP309 in prostate cancer patients suggests no correlation between a certain allelic variant and an increased cancer risk.

Molecular markers for bladder cancer: the road to a multimarker approach

Bladder cancer is the seventh most common malignancy worldwide, with almost 14,000 patients dying from this disease in the USA alone. Because of the need for long-term and frequent follow-up, as well as the paucity of sensitive and specific noninvasive tests, bladder cancer management has the highest cost per patient among all cancer types. Several molecular markers, especially members of the cell cycle regulation and apoptosis pathways, have been investigated. However, no individual marker has been prognostically powerful enough to change clinical management. The combined analysis of a panel of markers spanning different pathways is the most promising approach. We give an overview of the most important molecular markers functioning in crucial pathways and focus on their role in multimarker analysis.

Late age (85 years or older) peak incidence of bladder cancer

PURPOSE

We examined the incidence rates of bladder cancer using California Cancer Registry data to determine if any trends exist.

MATERIALS AND METHODS

Complete records of the 55,159 cases of invasive bladder cancer were examined from the original 92,677 bladder cancer cases recorded in the California Cancer Registry between 1988 and 2004.

RESULTS

California Cancer Registry data showed a universal late age peak in age specific incidence of bladder cancer in men and women, and across ethnic boundaries. The rate of annual increase in the percent of bladder cancer in individuals 85 years or older was increasing about 10 times as rapidly as the percent of the population that was 85 years or older (slope = 0.395 vs 0.0336). Furthermore, during all 17 years the proportion of patients 85 or older with bladder cancer was about twice that of patients with other cancers regardless of gender.

CONCLUSIONS

California Cancer Registry data illustrate a peak in the incidence of bladder cancer in individuals 85 years or older. However, to our knowledge there is no known explanation for this late peak in bladder cancer. With the rate of bladder cancer in the population 85 years or older increasing at a rapid pace, it is critical to encourage investigators to include this age group as they continue to search for causative factors and genetic contributors to bladder cancer as well as effective treatments.