Human papillomavirus seropositivity synergizes with MDM2 variants to increase the risk of oral squamous cell carcinoma

Identification of p53-target genes in human papillomavirus-associated head and neck cancer by integrative bioinformatics analysis

Introduction

Head and neck cancer (HNC) is a highly prevalent and heterogeneous malignancy. Although extensive efforts have been made to advance its treatment, the prognosis remained poor with increased mortality. Human papillomaviruses (HPV) have been associated with high risk in HNC. TP53, a tumor suppressor, is the most frequently altered gene in HNC, therefore, investigating its target genes for the identification of novel biomarkers or therapeutic targets in HPV-related HNC progression is highly recommended.

Methods

Transcriptomic profiles from three independent gene expression omnibus (GEO) datasets, including 44 HPV+ and 70 HPV- HNC patients, were subjected to integrative statistical and Bioinformatics analyses. For the top-selected marker, further in-silico validation in TCGA and GTEx databases and experimental validation in 65 (51 HPV- and 14 HPV+) subjects with histologically confirmed head and neck squamous cell carcinoma (HNSCC) have been performed.

Results

A total of 498 differentially expressed genes (DEGs) were identified including 291 up-regulated genes and 207 down-regulated genes in HPV+ compared to HPV- HNSCC patients. Functional annotations and gene set enrichment analysis (GSEA) showed that the up-regulated genes were significantly involved in p53-related pathways. The integrative analysis between the Hub-genes identified in the complex protein-protein network and the top frequent genes resulting from GSEA showed an intriguing correlation with five biomarkers which are EZH2, MDM2, PCNA, STAT5A and TYMS. Importantly, the MDM2 gene showed the highest gene expression difference between HPV+ and HPV- HNSCC (Average log2FC = 1.89). Further in-silico validation in a large HNSCC cohort from TCGA and GTEx databases confirmed the over-expression of MDM2 in HPV+ compared to HPV- HNSCC patients (p = 2.39E-05). IHC scoring showed that MDM2 protein expression was significantly higher in HPV+ compared to HPV- HNSCC patients (p = 0.031).

Discussion

Our findings showed evidence that over-expression of MDM2, proto-oncogene, may affect the occurrence and proliferation of HPV-associated HNSCC by disturbing the p53-target genes and consequently the p53-related pathways.

A Genome-Wide Association Study Identifies Two Novel Susceptible Regions for Squamous Cell Carcinoma of the Head and Neck

To identify genetic variants for risk of squamous cell carcinoma of the head and neck (SCCHN), we conducted a two-phase genome-wide association study consisting of 7,858,089 SNPs in 2,171 cases and 4,493 controls of non-Hispanic white, of which, 434,839 typed and 7,423,250 imputed SNPs were used as the discovery. SNPs with P < 1 × 10-3 were further validated in the OncoArray study of oral and pharynx cancer (5,205 cases and 3,232 controls of European ancestry) from databases of Genotypes and Phenotypes. Meta-analysis of the discovery and replication studies identified one novel locus 6p22.1 (P = 2.96 × 10-9 for the leading rs259919) and two cancer susceptibility loci 6p21.32 (rs3135001, HLA-DQB1) and 6p21.33 (rs1265081, CCHCR1) associated with SCCHN risk. Further stratification by tumor site revealed four known cancer loci (5p15.33, 6p21.32, 6p21.33, and 2p23.1) associated with oral cavity cancer risk and oropharyngeal cancer risk, respectively. In addition, one novel locus 18q22.2 (P = 2.54 × 10-9 for the leading SNP rs142021700) was identified for hypopharynx and larynx cancer risk. For SNPs in those reported or novel loci, we also performed functional annotations by bioinformatics prediction and expression quantitative trait loci analysis. Collectively, our identification of four reported loci (2p23.1, 5p15.33, 6p21.32, and 6p21.33) and two novel loci (6p22.1 and 18q22.2) for SCCHN risk highlight the importance of human leukocyte antigen loci for oropharyngeal cancer risk, suggesting that immunologic mechanisms are implicated in the etiology of this subset of SCCHN. SIGNIFICANCE: Two novel risk loci for SCCHN in non-Hispanic white individuals highlight the importance of immunologic mechanism in the disease etiology.

Combined Effect of HPV and Several Gene SNPs in Laryngeal Cancer

Background and objectives: Laryngeal squamous cell carcinoma (LSCC) is one of the most common head and neck tumors. The molecular mechanism of LSCC remains unclear. The aim of this study was to evaluate the prevalence of Human papillomavirus (HPV) and single nucleotide polymorphisms (SNPs) of TP53, MDM2, MDM4, MTHFR, CASP8, and CCR5 genes in LSCC, and to assess their correlations with patient survival. Materials and Methods: 49 LSCC patients were enrolled in this study. PCR and qRT-PCR were used to detect, identify, and quantify HPV. SNPs were genotyped using PCR and PCR-RFLP. Results: By analyzing the interactions of the SNPs of the genes with clinical parameters, the majority of patients with lymph node status (N1,2) were identified as carriers of MDM2T/G, CASP8ins/del, CCR5wt/wt SNP. Cluster analysis showed that patients with MDM2T/T SNP survive longer than patients identified as CASP8ins/ins, MTHFRC/C, and MDM4A/A variant carriers; meanwhile, LSCC patients with MDM2T/T polymorphic variant had the best survival. Multivariate analysis showed that HPV-positive patients without metastasis in regional lymph nodes (N0) and harboring CASP8ins/del variant had the best survival. Meanwhile, HPV-negative patients with identified metastasis in lymph nodes (N1 and N2) and CASP8ins/del variant had poor survival. Conclusions: This finding suggests patients survival prognosis and tumor behavior are different according HPV status, SNP variants, and clinical characteristics of the LSCC.

The Study of MDM2 rs937283 Variant and Cancer Susceptibility in a Central Chinese Population

The rs937283 variant, locating in murine double minute 2 promoter region, has been previously reported to potentially alter the promoter activity and to influence cancer susceptibility. In this study, we investigated the association of murine double minute 2 rs937283 variant and cancer susceptibility in a central Chinese population, followed by a meta-analysis. A total of 1058 healthy controls, 480 patients with breast cancer, 384 patients with cervical cancer, 480 patients with liver cancer, 426 patients with colon cancer, and 361 patients with rectal cancer were recruited in this case–control study. The murine double minute 2 rs937283 was genotyped by polymerase chain reaction restriction fragment length polymorphism and confirmed by sequencing. Our case–control analysis revealed that rs937283 was associated with the susceptibility to breast and liver cancer, but not cervical, colon, or rectal cancer. Specifically, the G allele of rs937283 conferred a significantly increased risk of breast and liver cancer. Moreover, results of meta-analysis demonstrated that rs937283 was significantly associated with cancer susceptibility, and this significant association remained in Asian (Chinese) population, but not in Caucasian population. Collectively, the murine double minute 2 rs937283 variant may serve as a potential biomarker for cancer predisposition in Chinese population.

Meta-Analysis Results on the Association Between TP53 Codon 72 Polymorphism With the Susceptibility to Oral Cancer

Objectives: TP53 is an important tumor suppressor gene to maintain genomic integrity, and its mutations increase the susceptibility to oral carcinoma. Previous published studies have reported the relation of TP53 codon 72 polymorphism with the risk of oral carcinoma, but the results remain controversial and inconclusive.

Methods: We therefore utilized meta-analysis based on a comprehensive search in PubMed, EMBASE, and Google of Scholar databases up to August 19, 2017.

Results: Total 3,525 cases and 3,712 controls from 21 case-control studies were selected. We found no significant association between TP53 codon 72 polymorphism and oral carcinoma susceptibility in all genetic contrast models, including subgroup analysis based on control source and ethnicity. Furthermore, TP53 codon 72 polymorphism was not significant associated with oral carcinoma susceptibility in tobacco or alcohol use, and HPV infection status. Our results were confirmed by sensitivity analysis and no publication bias was found.

Conclusions: Taken together, our data indicate that TP53 codon 72 polymorphism is not associated with the susceptibility to oral carcinoma.

The MDM2 rs937283 A > G variant significantly increases the risk of lung and gastric cancer in Chinese population

BACKGROUND

Currently, the MDM2 promoter rs937283 A > G variant that is able to alter MDM2 gene expression has been widely studied to explore the association of MDM2 with cancer risk. In this report, we investigate the association of MDM2 rs937283 A > G variant with risk of lung cancer (LC) and gastric cancer (GC) in a Chinese population of Hubei province, which was followed by a meta-analysis.

METHODS

The genotyping of rs937283 was performed by polymerase chain reaction-restriction fragment length polymorphism and confirmed by sequencing.

RESULTS

The results of the present study showed that rs937283 was significantly associated with the risk of LC, and the factors of age, gender, smoking status and drinking status would affect such association. However, rs937283 was only associated with the risk of GC in male, smoking and drinking subgroups. The following meta-analysis demonstrated that rs937283 was associated with the overall cancer risk particularly in Chinese population, which reinforced our present finding. Moreover, the meta-analysis according to cancer types revealed that rs937283 was associated with retinoblastoma risk, but not squamous cell carcinoma risk.

CONCLUSION

Collectively, the MDM2 rs937283 A > G variant may be a valuable risk factor or diagnostic biomarker for Chinese cancer patients.

Comprehensive review of genetic factors contributing to head and neck squamous cell carcinoma development in low-risk, nontraditional patients

BACKGROUND

The past 2 decades have seen an increased incidence of head and neck squamous cell carcinoma (HNSCC) in a nontraditional, low-risk patient population (ie, ≤45 years of age, no substance use history), owing to a combination of human papillomavirus (HPV) infection and individual genetic variation.

METHODS

Articles positing genetic variants as contributing factors in HNSCC incidence in low-risk, nontraditional patients were identified using a PubMed search, reviewed in detail, and concisely summarized herein.

RESULTS

Recent data suggest that common polymorphisms in DNA repair enzymes, cell-cycle control proteins, apoptotic pathway members, and Fanconi anemia-associated genes likely modulate susceptibility to HNSCC development in low-risk, nontraditional patients.

CONCLUSION

At present, there is a lack of robust, comprehensive data on genetic drivers of oncogenesis in low-risk patients and a clear need for further research on genetic alterations underlying the rising incidence of HNSCC in low-risk, nontraditional patients.

Modifying effect of mouse double minute-2 promoter variants on risk of recurrence for patients with squamous cell carcinoma of oropharynx

Functional mouse double minute-2 (MDM2) promoter variants may alter MDM2 expression and thus affect radiotherapy response and prognosis of squamous cell carcinoma of oropharynx (SCCOP). Thus we assessed association of 2 functional MDM2 promoter variants with recurrence risk of SCCOP. The disease-free survival (DFS) of patients with MDM2rs2279744 TT or MDM2rs937283 AA genotypes was significantly reduced compared with that of patients with corresponding GT/GG or AG/GG genotypes. Multivariable analysis showed patients with TT or AA genotypes had a significantly higher risk of SCCOP recurrence than those with corresponding GT/GG or AG/GG genotypes did. Furthermore, patients with combined risk genotypes of the 2 polymorphisms had significantly worse DFS and a higher recurrence risk than patients with fewer combined risk genotypes did (P_trend < 0.001). Compared with patients with 0 risk genotypes, patients with 1 or 2 risk genotypes had an approximately 3- or 11-fold increased risk of SCCOP recurrence, respectively. Notably, for both individual and combined polymorphisms, the above similar recurrence risks were particularly higher among patients with human papilloma virus (HPV)-positive tumors. Taken together, our findings suggest that MDM2 promoter variants individually, or more likely jointly, play a role in determining the risk of recurrence of SCCOP, particularly HPV-positive SCCOP.

Effect of human papillomavirus seropositivity and E2F2 promoter variants on risk of squamous cell carcinomas of oropharynx and oral cavity

Given roles of HPV and genetic factors in cancer risk, we evaluated associations of HPV16 seropositivity and five E2F2 promoter variants with squamous cell carcinoma of oropharynx (SCCOP) and squamous cell carcinoma of oral cavity (SCCOC) risk in a case-control study of 325 patients and 335 cancer-free matched controls. We found that HPV16 seropositivity was significantly associated with SCCOP risk (aOR, 5.4, 95%CI, 3.7-8.9) but not SCCOC (aOR, 0.8, 95%CI, 0.4-1.5), while each E2F2 polymorphism had no significant main effect on SCCOP and SCCOC risk. However, after combining HPV serological status and E2F2 promoter variants together, the modification effect of HPV serology and individual or combined risk genotypes of five polymorphisms on risk was significantly higher among SCCOP than among SCCOC. Furthermore, the stratified analysis by smoking status showed that all such modifying effects aforementioned on SCCOP were more pronounced in never smokers than in smokers. These findings are in agreement with those of previous studies, in which a majority of SCCOP were caused by HPV infection, whereas most SCCOC were found to be caused by smoking and drinking. Taken together, these findings indicate that the risk of SCCOP as opposed to SCCOC associated with HPV16 seropositivity was modified by E2F2 promoter variants either individually or jointly, especially in never smokers.

Influence of MDM2 polymorphisms on squamous cell carcinoma susceptibility: a meta-analysis

PURPOSE

Controversial associations between single-nucleotide polymorphisms (rs2279744, rs937283, rs3730485) of the MDM2 gene and the etiology of squamous cell carcinomas (SCCs) have been reported. This merits further comprehensive assessment.

MATERIALS AND METHODS

We systematically reviewed the available data and conducted an updated meta-analysis to evaluate the genetic effect of MDM2 polymorphisms in SCC susceptibility, using Stata/SE 12.0 software.

RESULTS

After screening, 7,987 SCC cases and 12,954 controls from 26 eligible case-control studies were enrolled. Overall, compared with the control group, a significantly increased SCC risk was observed for the MDM2 rs2279744 polymorphism in the Asian population (test of association: odds ratio [OR] 1.12, P=0.027 for G vs T; OR 1.26, P=0.016 for GG vs TT; OR 1.25, P<0.001 for GG vs TT + TG; and OR 1.08, P=0.023 for carrier G vs T). In subgroup analysis by SCC type, a similarly increased esophageal SCC risk was detected (OR 1.19, P<0.001 for G vs T; OR 1.46, P<0.001 for GG vs TT; and OR 1.48, P=0.005 for GG vs TT + TG). Furthermore, MDM2-TP53 double mutation was statistically associated with increased SCC susceptibility overall (OR 1.52, P=0.001), especially in the Asian population (OR 1.49, P=0.022). However, no significant difference between the control and case groups was obtained for MDM2 rs937283 or rs3730485 under any genetic model (all P>0.05).

CONCLUSION

Our results highlight a positive association between the GG genotype of MDM2 rs2279744 polymorphism and an increased risk of esophageal SCC in the Asian population, which needs to be clarified by more large-scale studies.

A Functional Polymorphism (rs937283) in the MDM2 Promoter Region is Associated with Poor Prognosis of Retinoblastoma in Chinese Han Population

The effect of single nucleotide polymorphisms (SNPs) at MDM2 has been investigated in several cancer types. Three MDM2 SNPs(rs937283, rs2270744 and rs769412) have previously been suggested to be positively correlated with cancer. In this study, we aimed to explore the association of rs937283, rs2270744 and rs769412 polymorphisms with retinoblastoma (RB) risk, clinicopathological characteristics, and prognosis. Compared with wild-type genotype AA at rs937283, individuals carrying AG and GG genotype had a significantly increased risk for developing RB (OR = 1.86, 95% CI 1.13–3.08; OR = 2.48, 95% CI 1.10–5.62, respectively). RB patients with allele G at rs937283 were more susceptible to invasion and high tumor aggression (OR = 2.42, 95% CI 1.43–4.11; OR = 2.15, 95% CI 1.27–3.64, respectively). Kaplan-Meier curves and log-rank results revealed that RB patients harboring genotype GG and G allele at rs937283 had worse survival (P < 0.02 and P < 0.01, respectively). In addition, the A to G substitution at rs937283 significantly enhanced the transcription activity of the MDM2 gene in vitro. In vivo, we found that MDM2 mRNA and protein were overexpressed in individuals who carried the G allele at rs937283. This study suggested that the MDM2 rs937283 polymorphism is a novel functional SNP both in vitro and in vivo as well as a biomarker for poor prognosis in RB.

Association of MDM2 promoter T309G polymorphism with oral cancer risk: A meta-analysis of 3,536 subjects

The mouse double minute 2 (MDM2) gene is an important regulator of the p53 suppressor gene. To date, evidence concerning the association of the MDM2 single nucleotide polymorphism (SNP) 309T>G (rs2279744) with the risk of developing oral squamous cell carcinoma (OSCC) remains controversial. Therefore, a meta-analysis of all the eligible studies was performed, in order to derive a more precise estimation of this association. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the degree of association in 5 previous studies, including a total of 1,369 OSCC cases and 2,167 controls. The overall analysis revealed a significant association between MDM2 SNP309 and OSCC risk in the heterozygote (TG vs. TT: OR=0.81; 95% CI: 0.68-0.96; P=0.02) and dominant models (TG+GG vs. TT: OR=0.82; 95% CI: 0.69-0.97; P=0.02). The subgroup analysis based on the source of the controls revealed a significant association between population-based controls and the heterozygote model (TG vs. TT: OR=0.75; 95% CI: 0.62-0.91; P=0.004), dominant model (TG+GG vs. TT: OR=0.76; 95% CI: 0.63-0.91; P=0.003) and allele comparison (G vs. T: OR=0.89; 95% CI: 0.79-0.99; P=0.04). Importantly, no evidence of publication bias or obvious heterogeneity were observed in the meta-analysis. The results of the present study demonstrated a decreased risk of developing OSCC for the MDM2 SNP309 group, suggesting MDM2 SNP309 may be a protection-associated genetic variation for OSCC. Additional well-designed studies, with larger sample sizes, are required to further elucidate this association.

Is MDM2 SNP309 Variation a Risk Factor for Head and Neck Carcinoma?: An Updated Meta-Analysis Based on 11,552 Individuals

Murine double minute-2 (MDM2) is a negative regulator of P53, and its T309G polymorphism has been suggested as a risk factor for a variety of cancers. Increasing evidence has shown the association of MDM2 T309G polymorphism with head and neck carcinoma (HNC) risk. However, the results are inconsistent. Thus, we performed a meta-analysis to elucidate the association. The meta-analysis retrieved studies published up to August 2015, and essential information was extracted for analysis. Separate analyses on ethnicity, source of controls, sample size, detection method, and cancer types were also conducted. Odds ratios (ORs) and their 95% confidence intervals (CIs) were used to estimate the association. Pooled data from 16 case-control studies including 4625 cases and 6927 controls failed to indicate a significant association. However, in the subgroup analysis of sample sizes, an increased risk was observed in the largest sample size group (>1000) under a recessive model (OR = 1.52; 95% CI = 1.08-2.13). Increased risks were also found in the nasopharyngeal cancer in the subgroup analysis of cancer types (GG vs TT: OR = 2.07; 95% CI = 1.38-3.12; dominant model: OR = 1.48; 95% CI = 1.13-1.93; recessive model: OR = 1.76; 95% CI = 1.17-2.65). The results suggest that homozygote GG alleles of MDM2 SNP309 may be a low-penetrant risk factor for HNC, and G allele may confer nasopharyngeal cancer susceptibility.

Impact of MDM2 single nucleotide polymorphism on oral squamous cell carcinoma risk

Mouse Double Minute 2 (MDM2) has emerged as a pivotal cellular antagonist of p53 by destructing the suppressive function of p53 against tumorigenesis. The MDM2 309 T > G polymorphism has been studied for its association with oral squamous cell carcinoma (OSCC) susceptibility, but the evidence was confusing and inconclusive. Here, we performed a meta-analysis to estimate the effects of the 309 T > G polymorphism on the development of OSCC. The relevant studies were searched on both PubMed and Embase. We estimated the risk of OSCC using odds ratio (OR) and 95 % confidence interval (CI). In addition, between-study heterogeneity was measured by the χ (2)-based statistic test; sensitivity analysis, and the funnel plots and Egger's test were also performed in this meta-analysis. Based on five case-control studies with a total of 1,369 OSCC cases and 2,167 control subjects, the meta-analysis result showed neither increased nor decreased risk of OSCC associated with any genetic model of the 309 T > G polymorphism. Similar results were observed in the subgroup of Asians. No significant heterogeneity and publication bias were detected in the meta-analysis. The evidence provided in our study indicated that the 309 T > G polymorphism might have no significant contribution to susceptibility toward OSCC.

Association of the recurrence of vocal leukoplakia with MDM2-309 variants over a 2-year period: a prospective study

CONCLUSION

MDM2-309 polymorphism variant genotypes decrease the risk of recurrence in vocal leukoplakia.

OBJECTIVE

The results of a previous study 2 years ago showed the effect of mouse double minute 2 homolog (MDM2) SNP309 polymorphisms in people with laryngeal carcinoma and vocal leukoplakia (a pre-cancerous laryngeal carcinoma lesion). This prospective, clinical trial was performed to assess the relationship between MDM2-309 polymorphism variants and recurrence/cancerization rates in people with vocal leukoplakia over a 2-year period.

PARTICIPANTS AND METHOD

A total of 61 post-operative patients with vocal leukoplakia participated in this prospective, observational, 2-year, follow-up study, and were genotyped for the MDM2-309 gene using pyrosequencing. Recurrence and cancerization rates were used to assess the relationship between the clinical outcome and the genotype variants.

RESULTS

The recurrence rate in the GT genotypes group was lower than that in the normal TT genotype group (17.2% vs 50%, p = 0.05) and there was a significantly lower recurrence rate in the GG genotype group than in the normal TT genotype group (10% vs 50%, p = 0.03). However, there was no statistically significant difference in the cancerization rate between the MDM2-309 variant (GT + GG) genotypes group and the normal TT genotype group (12.2% vs 8.3%, p > 0.05) over the 2-year follow-up period.

MDM2 T309G polymorphism and esophageal cancer risk: a meta-analysis

Murine double minute 2 (MDM2) has suggested to play an important role in esophageal cancer. The association between MDM2 T309G polymorphism and esophageal cancer risk was inconclusive. To clarify the possible association, we conducted a meta-analysis. We searched in the PubMed, Embase, and Wanfang databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. A total of 6 studies with 4909 cases and controls were included based on the search criteria. The MDM2 T309G polymorphism was associated with a significantly decreased risk of esophageal cancer (OR=0.88; 95% CI, 0.81-0.96; I(2)=22%). When stratified by type of race, a significantly decreased esophageal cancer risk were observed in Asians (OR=0.85; 95% CI, 0.78-0.93; I(2)=0%). In conclusion, this meta-analysis suggested that MDM2 T309G polymorphism was associated with a significantly decreased risk of esophageal cancer.

Autofluorescence imaging in recurrent oral squamous cell carcinoma

The survival of patients with oral cancer is decreased by locoregional recurrence after an initial multimodal treatment. In order to identify lesions in the oral cavity for a possible recurrence, clinical evaluation as well as MRI or CT scanning is advised. The evaluation of mucosa lesions is hampered by changes related to radio- and chemotherapy as well as reconstruction with tissue flaps. Several techniques for easier identification of tissue abnormalities in the oral cavity have been advocated as adjuncts in order to facilitate identification. Especially methods using altered tissue fluorescence have gained much interest during the last decade. The aim of our prospective study was to evaluate fluorescence properties of undiagnosed mucosa lesions with the VELscope device in patients with multimodal treated oral cancer prior to histological confirmation. In total, 41 patients with a history of oral squamous cell carcinomas (OSCC) (19 females and 22 males) with undiagnosed mucosa lesions where included in the study. After clinical evaluation, examination and documentation using the VELscope® device were performed. Then, an incisional biopsy was performed. An autofluorescence loss indicating a malignant or dysplastic mucosa condition could be detected in six patients (14.6 %); however, only one OSCC and one SIN revealed a complete autofluorescence loss. In four patients, OSCC was present in lesions with retained autofluorescence. Sensitivity and specificity for the VELscope® examination to identify malignant oral lesions by autofluorescence were 33.3 and 88.6 %, respectively. The positive and negative predictive values were 33.3 and 88.6 %, respectively. No statistical correlation between gender and lesion appearance versus autofluorescence loss could be detected. In contrast to mucosa lesions in patients with no prior treatment, the autofluorescence evaluation with the VELscope reveals no additional information in our analysis. Accordingly, invasive biopsies as gold standard are still needed to get sufficient evidence regarding potential malignancy in patients after multimodal treatment for oral cancer.

Genetic Variants of the MDM2 Gene Are Predictive of Treatment-Related Toxicities and Overall Survival in Patients With Advanced NSCLC

INTRODUCTION

Platinum agents can cause the formation of DNA adducts and induce apoptosis to eliminate tumor cells. The aim of the present study was to investigate the influence of genetic variants of MDM2 on chemotherapy-related toxicities and clinical outcomes in patients with advanced non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

We recruited 663 patients with advanced NSCLC who had been treated with first-line platinum-based chemotherapy. Five tagging single nucleotide polymorphisms (SNPs) in MDM2 were genotyped in these patients. The associations of these SNPs with clinical toxicities and outcomes were evaluated using logistic regression and Cox regression analyses.

RESULTS

Two SNPs (rs1470383 and rs1690924) showed significant associations with chemotherapy-related toxicities (ie, overall, hematologic, and gastrointestinal toxicity). Compared with the wild genotype AA carriers, patients with the GG genotype of rs1470383 had an increased risk of overall toxicity (odds ratio [OR], 3.28; 95% confidence interval [CI], 1.34-8.02; P = .009) and hematologic toxicity (OR, 4.10; 95% CI, 1.73-9.71; P = .001). Likewise, patients with the AG genotype of rs1690924 showed more sensitivity to gastrointestinal toxicity than did those with the wild-type homozygote GG (OR, 2.32; 95% CI, 1.30-4.14; P = .004). Stratified survival analysis revealed significant associations between rs1470383 genotypes and overall survival in patients without overall or hematologic toxicity (P = .007 and P = .0009, respectively).

CONCLUSION

The results of our study suggest that SNPs in MDM2 might be used to predict the toxicities of platinum-based chemotherapy and overall survival in patients with advanced NSCLC. Additional validations of the association are warranted.

Human papillomavirus and host genetic polymorphisms in carcinogenesis: a systematic review and meta-analysis

BACKGROUND

As the role of human papillomavirus (HPV) in carcinogenesis continues to rise, the role of genetic factors that modify this risk have become increasingly important. In this study, we reviewed the literature for associations between polymorphisms and HPV in carcinogenesis.

OBJECTIVE

To identify any associations of genetic polymorphisms with oncogenic HPV in carcinogenesis and to evaluate the methodology used.

STUDY DESIGN

Systematic literature review of HPV, genetic polymorphisms, and cancer risk. Odds ratios (OR), interaction terms, and p-values were tabulated. Meta-analyses and measures of heterogeneity were estimated using RevMan 5.1.

RESULTS

The cervix was the most frequently studied cancer site followed by the head and neck. Overall risk of cancer (cancer vs. control) was the most common comparison, whereas reports of initiation (pre-cancer vs. control) and progression (cancer vs. pre-cancer) were rare. Case-series and joint-effect of HPV and genotype on risk was evaluated frequently, but the independent effect of either risk factor alone was rarely provided. P53-Arg72Pro was the most commonly studied polymorphism studied. No consistent interaction was detected by meta-analysis in the HPV(+) [OR 0.98 (0.55-1.76)] or the HPV(-) [OR 1.10 (0.76-1.60)] subsets in head and neck cancer risk. Polymorphisms in genes known to encode proteins that physically interact with HPV were infrequently studied.

CONCLUSION

No consistent polymorphism-HPV interactions were observed. Study design, choice of candidate polymorphisms/genes, and a focus on overall risk rather than any specific portions of the carcinogenic pathway may have contributed to lack of significant findings.

MDM2 polymorphism associated with the development of cervical lesions in women infected with Human papillomavirus and using of oral contraceptives

Background

The MDM2 gene is the major negative regulator of p53, a tumor suppressor protein. Single nucleotide polymorphism in promoter region of MDM2 gene leads to increased expression resulting in higher levels of MDM2 protein. This event increases the attenuation of the p53 pathway. Polymorphisms in this gene can interfere in the regulation of cellular proliferation. We evaluated whether MDM2 SNP309 (rs2278744) associated or not with the use of oral contraceptive can heighten susceptibility to development of cervical lesions in women HPV infected.

Methods

MDM2 SNP309 (rs2278744) was genotyped in a total of 287 patients using the PCR-RFLP technique. The results were analyzed by UNPHASED v.3.121 and SNPStats programs.

Results

The three groups (SIL, LSIL and HSIL) showed no significant differences in either genotype or allelic frequencies for MDM2 polymorphisms, except when HSIL was compared with LSIL (p = 0.037; OR = 1.81). Furthermore, in the analysis of contraceptives, a significant association was found between the use of contraceptives and the MDM2 variant in the development of high-grade cervical lesions for the TG genotype (p = 0.019; OR = 2.21) when HSIL was compared with control. When HSIL was compared with LSIL (p = 0.006; OR = 2.27).

Conclusion

The results of this study suggest that MDM2 SNP309 might be a good marker for assessing the progression of LSIL to HSIL. In addition, they also show that oral contraceptives alone, did not have any effect on the progression or development of cervical lesions. However, they may act synergistically with MDM2 SNP309 (rs2278744) and HPV infection in the development of cervical lesions.

E3 ubiquitin ligases and human papillomavirus-induced carcinogenesis

Human papillomavirus (HPV) infection is clinically very common. It is usually a major risk factor in the development of cutaneous benign lesions, cervical cancer and a variety of other malignancies. The biological function of ubiquitination as an intracellular proteasomal-mediated form of protein degradation and an important modulator in the regulation of many fundamental cellular processes has been increasingly recognized over the last decade. HPV proteins have been demonstrated to evolve different strategies to utilize the ubiquitin system for their own purposes. The putative roles of E3 ubiquitin ligases in HPV-induced carcinogenesis have become increasingly apparent, although the mechanisms remain unclear. In this review we provide an update on the mechanisms of the involvement of E3 ubiquitin ligases in HPV-induced carcinogenesis, focusing on their interaction with HPV proteins and their roles in several signalling pathways. Targeting the E3 ubiquitin ligases might offer potential therapeutic strategies for HPV-related diseases in future.

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.

Telomere length in peripheral blood lymphocytes contributes to the development of HPV-associated oropharyngeal carcinoma

Sexual transmission of human papillomavirus (HPV), particularly HPV16, has been associated with an increasing incidence of oropharyngeal squamous cell carcinoma (OPC). Telomere shortening results in chromosomal instability, subsequently leading to cancer development. Given that HPV16 can affect telomerase activity and telomere length, we conjectured that telomere length in peripheral blood lymphocytes (PBL) might affect the risk of HPV16-associated OPC and tumor HPV16 status in patients. Telomere length in PBLs and HPV16 serologic status were measured in peripheral blood samples in 188 patients with OPC, 137 patients with oral cavity cancer (OCC) and 335 controls of non-Hispanic Whites. Tumor HPV status was determined in 349 OPC cases. ORs and 95% confidence intervals were calculated in univariate and multivariable logistic regression models. Overall, as compared with the long telomere length, short telomere length was significantly associated with a moderately increased risk of OPC but not with increased risk of OCC. When we stratified the data by HPV16 serologic status, using long telomere length and HPV16 seronegativity as the reference group, we found that the risk associated with HPV16 seropositivity was higher among patients with OPC with short telomere length. Notably, such risk was particularly pronounced in never smokers, never drinkers, and those more than 50 years of age. Furthermore, short telomere length was also associated significantly with tumor HPV-positive OPC. Together, our findings suggest that telomere length in PBLs may be associated with higher risk of HPV16-associated OPC and tumor HPV16 status, particularly in certain patient subgroups. Larger studies are needed to validate these findings.

Association of p53 and MDM2 polymorphisms with risk of human papillomavirus (HPV)-related esophageal squamous cell carcinoma (ESCC)

PURPOSE

Though polymorphisms of the tumor suppressor gene p53 have been extensively investigated in numerous tumors, particularly tumors associated with human papillomavirus (HPV) infection. However, the results remain controversial. Our previous study showed that HPV serostatus is not an independent risk factor for esophageal squamous cell carcinoma (ESCC) in nonsmokers and nondrinkers. Given the roles of p53 and HPV E6 as well as MDM2 oncoproteins in p53 degradation, we validated the association of p53 and MDM2 polymorphisms with ESCC risk stratified by HPV16 sero-status.

METHODS

Single nucleotide polymorphisms of p53 Arg72Pro (rs1042522) and MDM2 (rs937283) in 307 ESCC patients and 311 healthy controls were genotyped. The presence or absence of HPV16 in serum was measured by enzyme-linked immunosorbent assay. Multivariable logistic regression analysis was used to evaluate the possible associations of p53 and MDM2 polymorphisms with ESCC risk stratified by HPV16 sero-status.

RESULTS

Patients carrying p53 Arg/Arg or Arg/Pro had a higher risk of esophageal SCC (P<0.001, Odds ratio [OR] 4.98, 95% confidential interval [CI] 3.46-7.17), however, not found in MDM2 rs937283. The risk of esophageal SCC increased significantly among patients carrying p53 Arg/Arg, or Arg/Pro and HPV16-seropositivity (P<0.001, OR 9.33, 95% CI 5.44-16.0), but not for MDM2 rs937283. The risk of esophageal SCC was further elevated among patients carrying Arg/Arg or Arg/Pro and HPV16-seropositivity who were smokers (P<0.001, OR 27.05, 95% CI 11.06-66.16) or drinkers (P<0.001, OR 13.20, 95% CI 5.74-30.38).

CONCLUSION

HPV16 seropositivity synergized with p53 Arg/Arg or Arg/Pro and increased ESCC risk, especially in smokers or drinkers.

Epidemiology of oral-cavity and oropharyngeal carcinomas: controlling a tobacco epidemic while a human papillomavirus epidemic emerges

Although tobacco prevalence is declining in most developed countries, less developed countries are still experiencing an increase in tobacco use. Thus the future burden of oral-cavity and oropharyngeal cancers in less developed countries is expected to be heavy. The incidence of human papillomavirus (HPV)-associated oropharyngeal cancer is dramatically increasing in the United States and other developed countries, although trends in less developed countries are not clear at present. HPV vaccine compliance in the United States is low, although it continues to increase each year. Increasing the HPV vaccination rate to control future HPV-associated cancer incidence remains a priority.

Human papillomavirus and diseases of the upper airway: head and neck cancer and respiratory papillomatosis

Human papillomavirus (HPV) infection is causally associated with benign and malignant diseases of the upper airway, including respiratory papillomatosis and oropharyngeal cancer. Low-risk HPV types 6 and 11 are the predominant cause of papillomatosis, whereas only HPV16 definitively satisfies both molecular and epidemiological causal criteria as a carcinogenic or high-risk type in the upper airway. HPV16 E6/E7 mRNA expression and integration are observed predominantly among oropharyngeal cancers, and experimental models have shown E6/E7 expression to be necessary for the initiation and maintenance of the malignant phenotype of these cancers. From an epidemiological perspective, a strong and consistent association between markers of HPV16 exposure and oropharyngeal cancer has been demonstrated in numerous case-control studies. HPV-positive oropharyngeal cancers have also been shown to be distinct from HPV-negative head and neck squamous cell cancers with regard to risk-factor profiles, molecular genetic alterations, population-level incidence trends over time, and prognosis. Tumor HPV status (as determined by certain HPV16 in situ hybridization assays or certain p16 immunohistochemistry assays) is the strongest determinant of survival for patients with local-regionally advanced oropharyngeal cancer: patients with HPV-positive cancer have at least a 50% improvement in overall survival at 5 years, which is equivalent to an approximate 30% difference in absolute survival. Thus, HPV status determination is now part of the routine diagnostic evaluation for prognostication. Preliminary evidence indicates that a small proportion of head and neck cancers may be caused by additional HPV types (e.g., 18, 31, 33, 35) and that HPV-caused cancers may rarely arise from non-oropharyngeal sites (e.g., the oral cavity, nasopharynx, and larynx). Whether or not HPV vaccination has the potential to prevent oral HPV infections that lead to cancer or papillomatosis in the upper airway is currently unknown, as is the potential for secondary prevention with HPV detection. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

MicroRNA variants increase the risk of HPV-associated squamous cell carcinoma of the oropharynx in never smokers

BACKGROUND

Both microRNAs and human papillomavirus (HPV) infection play an important role in the development and progression of oral squamous cell carcinoma (OSCC). In addition, microRNAs affect all facets of the immune/inflammation responses to infection, which may control HPV clearance. We thus hypothesized that microRNA polymorphisms modify the association between HPV16 seropositivity and OSCC risk.

METHODS

Four single-nucleotide polymorphisms in microRNAs were genotyped and HPV16 serology was determined in 325 cases and 335 matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using univariate and multivariable logistic regression models.

RESULTS

Overall, each polymorphism had no significant main effect on OSCC risk. Compared with the risk among individuals with both miR146 rs2910164 GG genotype and HPV16 seronegativity, risk of OSCC was increased among those with CG or CC genotype and HPV16 seronegativity (OR, 1.2; 95% CI, 0.9-1.8), GG genotype and HPV16 seropositivity (OR, 3.0; 95% CI, 1.8-5.0), and CG or CC genotype and HPV16 seropositivity (OR, 4.7; 95% CI, 2.3-9.4). Similar results were found for miR149 rs2292832, miR196 rs11614913, and miR499 rs3746444. Analyses stratified by tumor sites and smoking status showed that each polymorphism significantly increased the risk of HPV16-associated squamous cell carcinoma of the oropharynx (SCCOP), and such effect modification was particularly prominent in never smokers.

CONCLUSIONS

Our results indicate that microRNA polymorphisms modify the risk of OSCC associated with HPV16 seropositivity, particularly in patients with SCCOP and never smokers. Larger studies are needed to verify our findings.

Genetic variants of NOXA and MCL1 modify the risk of HPV16-associated squamous cell carcinoma of the head and neck

Abstracts

Downregulation of Mdm2 and Mdm4 enhances viral gene expression during adenovirus infection

Successful viral replication entails elimination or bypass of host antiviral mechanisms. Here, we show that shRNA-mediated knockdown of murine double minute (Mdm2) and its paralog Mdm4 enhanced the expression of early and late viral gene products during adenovirus (HAdV) infection. Remarkably, whereas the expression of HAdV genes was low in p53-deficient mouse embryonic fibroblasts (p53KO MEFs), the HAdV early gene products were efficiently expressed in Mdm2/p53 double-knockout (DKO) and Mdm4/p53 DKO MEFs, and viral capsid proteins were produced in Mdm2/p53 DKO MEFs. Thus, Mdm2 and Mdm4 seem to have potent antiviral property. In cells infected with wt HAdV or a mutant virus lacking the E1B-55K gene (dl 1520), both Mdm2 and Mdm4 were rapidly depleted, whereas replication-deficient mutant viruses (Ad-GFP) or ΔpTP with deletions within the coding sequence of preterminal binding protein failed to induce their downregulation. Reduced expression of Mdm2 and Mdm4 was not due to general shutoff of host protein synthesis. Additionally, expression of a dominant-negative mutant of Cul5 did not affect Mdm2/Mdm4 downregulation. Thus, viral replication but not the presence of E1B-55K is required for Mdm2/Mdm4 degradation. Surprisingly, treatment of HAdV-infected cells with proteasome inhibitor MG132 only partially restored the protein levels of Mdm2 and Mdm4, suggesting that they may also be downregulated through an additional mechanism independent of proteasome. Interestingly, cyclin D1 and p21 appear to be downregulated similarly during HAdV infection. Collectively, our work provides the first biochemical evidence for antiviral function of Mdm2 and Mdm4 and that viruses employ efficient countermeasure to ensure viral replication.

The Role of p53 and MDM2 in Head and Neck Cancer

Head and neck cancer is a complex disorder that includes mostly squamous cell carcinomas that can develop in the throat, larynx, nose, sinuses, and mouth. Etiopathogenesis is due to tobacco and alcohol consumption and to infection by human papillomavirus (HPV) type 16/18. Tumors often develop within preneoplastic fields of genetically altered cells. Most head and neck cancers result from multistep accumulation of genetic alterationsm resulting in clonal outgrowth of transformed cells. These DNA changes are caused by a variety of mechanisms like endogenous mutations and exogenous mutations. Dysregulated molecular pathway includes alterations of critical inhibitor of cyclin CDK complexes, inactivating mutations of p53 gene, and activation of oncogenes and growth factors. This paper attempts to review the role of p53 and MDM2 genetic aberrations and pathways in head and neck cancer.

Combined p53-related genetic variants together with HPV infection increase oral cancer risk

To explore the role of polymorphisms of p53-related genes in etiology of oral cancer, we investigated joint effects of seven putatively functional polymorphisms of p53 (codon 72 Arg/Pro), p73 (4/14 GC/AT), murine double minute 2 gene (MDM2; A2164G and T2580G) and MDM4 (rs11801299 G > A, rs10900598 G > T and rs1380576 C > G) on risk of human papillomavirus (HPV)16-associated oral cancer in a case-control study with 325 cases and 335 cancer-free controls. We found that HPV16 seropositivity alone was associated with an increased risk of oral cancer [adjusted odds ratio (OR), 3.1; 95% confidence interval (CI), 2.1-4.6]. After combining genotypes of seven polymorphisms and using the low-risk group (0-3 combined risk genotypes) and HPV16 seronegativity as the reference group, the medium-risk (4 combined risk genotypes) and high-risk groups (5-7 combined risk genotypes) and HPV16 seronegativity were associated with only an OR of 1.6 (95% CI, 1.1-2.5) and 1.2 (95% CI, 0.7-1.9) for oral cancer risk, respectively, whereas the low-risk, medium-risk and high-risk groups and HPV16 seropositivity were significantly associated with a higher OR of 2.1 (95% CI, 1.2-3.6), 4.0 (95% CI, 1.8-9.1) and 19.1 (95% CI, 5.7-64.2), respectively. Notably, such effect modification by these combined risk genotypes was particularly pronounced in young subjects (aged < 50 years), never smokers and patients with oropharyngeal cancer. Taken together, these findings suggest that the combined risk genotypes of p53-related genes may modify risk of HPV16-associated oral cancer, especially in young patients, never-smokers and patients with oropharyngeal cancer. Larger studies are needed to validate our findings.

Genetic variants of a BH3-only pro-apoptotic gene, PUMA, and risk of HPV16-associated squamous cell carcinoma of the head and neck

P53 up-regulated modulator of apoptosis (PUMA) is a critical factor in the intrinsic apoptotic pathway. Through PUMA-dependent mechanisms, human papillomavirus 16 (HPV16) oncoprotein may affect apoptosis by E6-mediated p53 degradation. To examine whether the PUMA variants modify the association between HPV16 serology and risk of squamous cell carcinoma of the head and neck (SCCHN), we genotyped two polymorphisms in the PUMA promoter (rs3810294 and rs2032809) in 380 cases and 335 cancer-free controls of non-Hispanic Whites, who were frequency-matched by age (±5 yr), sex, smoking, and drinking status. We found that each individual polymorphism had only a modest impact on risk of SCCHN, particularly in oropharyngeal cancer for rs3810294 and non-oropharyngeal cancer for rs2032809. After we stratified the individuals by HPV16 serology, and used those with the corresponding common homozygous genotype and HPV16 seronegativity as the reference group, for each polymorphism we found that the risk of SCCHN associated with HPV16 seropositivity was higher among those with variant genotypes than those with the corresponding common homozygous genotype. Notably, this effect modification was particularly pronounced in several subgroups including never smokers, never drinkers, younger patients, and patients with oropharyngeal cancer. Furthermore, we also characterized the functional relevance of the two polymorphisms to explore the genotype-phenotype correlation. Our results suggested that the PUMA promoter polymorphisms may be a biomarker for risk of HPV16-associated SCCHN, particularly in never smokers, never drinkers, younger patients, and patients with oropharyngeal cancer. Larger studies are needed to validate our findings.

Polymorphisms of MDM4 and risk of squamous cell carcinoma of the head and neck

PURPOSE

Mouse double minute 4 (MDM4), a homolog of MDM2, is one of the key negative regulators of p53, and its amplification or overexpression contributes to carcinogenesis by inhibiting the p53 tumor suppressor activity. We investigated the association between MDM4 polymorphisms and the risk of squamous cell carcinoma of the head and neck (SCCHN).

METHODS

We genotyped three MDM4 tagging polymorphisms, two in the 3' untranslated region (rs11801299G>A and rs10900598G>T) and one in intron 1 (rs1380576C>G), in a case-control study of 1075 non-Hispanic white SCCHN patients and 1079 cancer-free controls, and evaluated their associations with SCCHN risk.

RESULTS

Although none of these three polymorphisms individually had a statistically significant effect on the risk of SCCHN, nor did their combined number of putative risk genotypes (i.e. rs11801299GG, rs1380576CG+GG, and rs10900598GG) [odds ratio (OR)=1.16; 95% confidence interval (95% CI) =0.93-1.45], we found that individuals with 1-3 risk genotypes had statistically significant increased risk of oropharyngeal cancer (OR=1.32; 95% CI=1.00-1.73), particularly for those with T1-2 stage (OR=1.40; 95% CI=1.02-1.94), those with regional lymph node metastases (N1-3) (OR=1.44; 95% CI=1.07-1.95), and those with late stages (III and IV) (OR=1.34; 95% CI=1.01-1.77).

CONCLUSION

These results suggest that the joint effect of MDM4 variants may contribute to the risk of oropharyngeal cancer in non-Hispanic whites. Additional studies are warranted to unravel whether the particular stage distribution of oropharyngeal cancer with the strongest association (T1-2, N1-3, and III-IV) is a possible link with human papillomavirus-related oropharyngeal cancers.

MDM2 SNP309 contributes to tumor susceptibility: a meta-analysis

The potentially functional polymorphism, SNP309, in the promoter region of MDM2 gene has been implicated in cancer risk, but individual published studies showed inconclusive results. To obtain a more precise estimate of the association between MDM2 SNP309 and risk of cancer, we performed a meta-analysis of 70 individual studies in 59 publications that included 26,160 cases with different types of tumors and 33,046 controls. Summary odds ratios (OR) and corresponding 95% confidence intervals (CIs) were estimated using fixed- and random-effects models when appropriate. Overall, the variant genotypes were associated with a significantly increased cancer risk for all cancer types in different genetic models (GG vs. TT: OR, 1.123; 95% CI, 1.056-1.193; GG/GT vs. TT: OR, 1.028; 95% CI, 1.006-1.050). In the stratified analyses, the increased risk remained for the studies of most types of cancers, Asian populations, and hospital- /population-based studies in different genetic models, whereas significantly decreased risk was found in prostate cancer (GG vs. TT: OR, 0.606; 95% CI, 0.407-0.903; GG/GT vs. TT: OR, 0.748; 95% CI, 0.579-0.968). In conclusion, the data of meta-analysis suggests that MDM2 SNP309 is a potential biomarker for cancer risk.