SH3GL2 and CDKN2A/2B loci are independently altered in early dysplastic lesions of head and neck: correlation with HPV infection and tobacco habit

Biomarkers and Prognostic Stratification of Squamous Cell Carcinoma of the Oral Cavity in Young Adults: How to Personalize Therapeutic Management?

Squamous cell carcinomas of the oral cavity in young adults represent a heterogeneous entity. New prognostic biomarkers are described in the literature. The aim of this review was to identify emerging biomarkers and prognostic stratification factors of young population. Clinical, biological, microbiological, histopathologic, and molecular markers statistically associated with overall survival (OS) and disease-free survival and were validated in literature. Young adults <40 years of age who were nonsmokers showed a marginally worse prognosis, whereas those <30 years of age showed unfavorable prognosis compared with those with >30 years of age. The high rate of neutrophil-to-lymphocyte ratio was associated with decreased 5-year disease-specific survival, PD-L1 expression correlated with improved OS and recurrence-free survival, and the presence of Fusobacterium and mutations in p53, cyclin D1, and VEGF were associated with reduced OS. Combining these markers in young adults with oral cavity squamous cell carcinomas should be used to adapt the intensification of therapy in addition to the tumor-node-metastasis classification and minor histoprognostic factors.

Molecular characterization of the evolution of premalignant lesions in the upper aerodigestive tract

Introduction

Early relapse and development of metastatic disease are some of the primary reasons for the poor prognosis of patients with head and neck squamous cell carcinoma (HNSCC). HNSCC is a heterogeneous disease which may develop in large premalignant fields of genetically altered cells. Yet knowing which individuals will progress and develop clinically significant cancers during their lifetimes remains one of the most important challenges of reducing HNSCC morbidity and mortality. To further elucidate the molecular mechanisms, we performed a focused analysis of the genome and immune microenvironment from multiple, matched normal squamous tissue, premalignant lesions, as well as primary and recurrent tumors from seven patients with p16-negative HNSCC.

Methods

We performed targeted panel Next Generation Sequencing (161 genes) to analyze somatic variants from sequentially collected, matched formalin-fixed paraffin-embedded tissue (normal, premalignant, HNSCC) from two patients. These samples plus samples from five additional patients were analyzed with the Nanostring PanCancer Immune Panel. In addition, we performed shallow whole genome sequencing (0.5x coverage on average) on samples from three of these patients. Patients were, apart from one case, primarily treated with curative-intent surgery, and received subsequent adjuvant treatment, if indicated.

Results

The most frequently mutated genes were TP53 and NOTCH1. Other mutated genes included NOTCH3 and CDKN2A, among others. A significant number of mutations were private to dysplasia and invasive carcinoma, respectively, however, almost 20% were shared between them. Increasing genomic instability was observed when comparing histologically normal squamous mucosa with higher levels of dysplasia. High-grade dysplasia showed similarly rearranged genomes as invasive carcinoma. Pathways related to interferon alpha and gamma response were upregulated even in moderate dysplastic lesions with increasing expression in higher grades of dysplasia and carcinoma. SPINK5, a known tumor suppressor gene in HNSCC, was already downregulated in low-grade dysplastic lesions, indicating an early deactivation in the evolution of the disease.

Conclusion

Genomic alterations as well as aberrant immune gene expression can be observed early in the evolution of tumors of the upper aerodigestive tract, highlighting the potential for targeting early mechanisms of disease progression.

Inferring early genetic progression in cancers with unobtainable premalignant disease

Analysis of premalignant tissue has identified the typical order of somatic events leading to invasive tumors in several cancer types. For other cancers, premalignant tissue is unobtainable, leaving genetic progression unknown. Here, we demonstrate how to infer progression from exome sequencing of primary tumors. Our computational method, PhylogicNDT, recapitulated the previous experimentally determined genetic progression of human papillomavirus-negative (HPV^-) head and neck squamous cell carcinoma (HNSCC). We then evaluated HPV⁺ HNSCC, which lacks premalignant tissue, and uncovered its previously unknown progression, identifying early drivers. We converted relative timing estimates of driver mutations and HPV integration to years before diagnosis based on a clock-like mutational signature. We associated the timing of transitions to aneuploidy with increased intratumor genetic heterogeneity and shorter overall survival. Our approach can establish previously unknown early genetic progression of cancers with unobtainable premalignant tissue, supporting development of experimental models and methods for early detection, interception and prognostication.

An Overview of DNA Methylation Indicators for the Course of Oral Precancer

DNA methylation is a physiologically epigenetic alteration that happens when a methyl group is introduced to a CpG dinucleotide in the gene-regulating sequence of DNA. However, the majority of oral cancers have a well-defined precancerous stage; there are few clinical and morphological parameters for detecting and signalling the progression of precancerous to malignant tumours. DNA methylation forms are dynamic and reversible, allowing them to adjust to environmental or therapeutic changes. We did an extensive investigation to compile the data supporting aberrant DNA methylation forms as a possible biomarker for prediction. According to two longitudinal studies, p16 hypermethylation was considerably higher in precancerous lesions that progressed to cancer than in lesions that shrank. Most of the studies examined for this study were tiny cross-sectional research with scant validation and inadequately specified control groups. Existing evidence suggests that DNA methylation sequences can be relevant as a diagnostic biomarker for OPS development; however, sample size and research design restrictions make it difficult to draw definitive conclusions. Strong studies, including extensive epigenome-wide methylation scans of OPS with longitudinal monitoring, are necessary in this study in order to corroborate the recently discovered signals and discover new risk loci and disease progression molecular pathways.

Farnesoid X receptor functions in cervical cancer via the p14ARF-mouse double minute 2-p53 pathway

BACKGROUND

Cervical cancer is the second most common cancer among women living in developing countries. Farnesoid X receptor (FXR) is a member of the nuclear receptor family, which regulates the development and proliferation of cancer. However, the role of and molecular mechanism by which FXR acts in cervical cancer are still unknown.

METHODS AND RESULTS

The relationship between FXR and the proliferation of cervical cancer cell lines was detected by MTT and colony formation assays. Immunohistochemistry was used to detect the expression of FXR in cervical cancer tissue slides. Western blotting was used to detect the expression of p14^ARF, mouse double minute 2 (MDM2) and p53 when FXR was overexpressed or siRNA was applied. Western blotting was used to detect the expression of MDM2 and p53 when pifithrin-α (PFT-α) was applied. FXR activation inhibited the proliferation of cervical cancer cell lines. FXR was significantly decreased in cervical squamous cell carcinoma, which was correlated with TNM stage, but not with metastasis. Overexpression of FXR activated the p14^ARF-MDM2-p53 pathway. As a p53 inhibitor, PFT-α increased MDM2 in Lenti-vector cells, but had no effect on MDM2 in Lenti-FXR cells.

CONCLUSIONS

FXR inhibits cervical cancer by upregulating the p14^ARF-MDM2-p53 pathway. Activation of FXR may be a potential strategy for the treatment of cervical cancer.

On the Cutting Edge of Oral Cancer Prevention: Finding Risk-Predictive Markers in Precancerous Lesions by Longitudinal Studies

Early identification and management of precancerous lesions at high risk of developing cancers is the most effective and economical way to reduce the incidence, mortality, and morbidity of cancers as well as minimizing treatment-related complications, including pain, impaired functions, and disfiguration. Reliable cancer-risk-predictive markers play an important role in enabling evidence-based decision making as well as providing mechanistic insight into the malignant conversion of precancerous lesions. The focus of this article is to review updates on markers that may predict the risk of oral premalignant lesions (OPLs) in developing into oral squamous cell carcinomas (OSCCs), which can logically be discovered only by prospective or retrospective longitudinal studies that analyze pre-progression OPL samples with long-term follow-up outcomes. These risk-predictive markers are different from those that prognosticate the survival outcome of cancers after they have been diagnosed and treated, or those that differentiate between different lesion types and stages. Up-to-date knowledge on cancer-risk-predictive markers discovered by longitudinally followed studies will be reviewed. The goal of this endeavor is to use this information as a starting point to address some key challenges limiting our progress in this area in the hope of achieving effective translation of research discoveries into new clinical interventions.

Detection of human papillomavirus infection in oral cancers reported at dental facility: assessing the utility of FFPE tissues

Incidence of human papillomavirus (HPV)-associated oral cancers is on the rise. However, epidemiological data of this subset of cancers are limited. Dental hospital poses a unique advantage in detection of HPV-positive oral malignancies. We assessed the utility of formalin-fixed paraffin-embedded (FFPE) tissues, which are readily available, for evaluation of high-risk HPV infection in oral cancer. For protocol standardization, we used 20 prospectively collected paired FFPE and fresh tissues of histopathologically confirmed oral cancer cases reported in Oral Medicine department of a dental hospital for comparative study. Only short PCRs (~ 200 bp) of DNA isolated using a modified xylene-free method displayed a concordant HPV result. For HPV analysis, we used additional 30 retrospectively collected FFPE tissues. DNA isolated from these specimens showed an overall 23.4% (11/47) HPV positivity with detection of HPV18. Comparison of HPV positivity from dental hospital FFPE specimens with overall HPV positivity of freshly collected oral cancer specimens (n = 55) from three cancer care hospitals of the same region showed notable difference (12.7%; 7/55). Further, cancer hospital specimens showed HPV16 positivity and displayed a characteristic difference in reported sub-sites and patient spectrum. Overall, using a xylene-free FFPE DNA isolation method clubbed with short amplicon PCR, we showed detection of HPV-positive oral cancer in dental hospitals.

Occurrence of Epidermal Growth Factor Receptor Expression in Squamous Cell Carcinoma of Oral Cavity and Adjacent Sites: A Retrospective Observational Study

Introduction Oral cavity squamous cell carcinomas (OCSCCs) are one of the most common malignancies encountered. They have diverse clinicopathologic profiles. Epidermal growth factor receptor (EGFR) is an important marker of OCSCC for diagnosis, prognosis, and therapy.

Objective The study aimed to evaluate the distribution of clinicopathological parameters in cases of squamous cell carcinoma (SCC) of the oral cavity and adjacent sites and their EGFR expression. An attempt was made to correlate EGFR scores with different parameters.

Materials and Methods An observational retrospective study was undertaken for 1 year. Patients with histologically proven SCC of the oral cavity and adjacent sites were included. Clinicopathologic and immunohistochemical features of each case were analyzed.

Results A total of 59 cases of SCC were included of which 41 (69%) were males. The mean age of the patients was 56.4 ± 10.3 years. The most common location of the tumors was oral cavity (31, 53%) followed by larynx (10, 16%). Most cases were moderately differentiated tumors (31, 53%). Immunohistochemical analysis showed low EGFR score in 7 (11.9%) cases, intermediate in 6 (10.1%), and high in 46 (78%) cases. Association between gender of patients and EGFR score was statistically significant (p = 0.000159). Most lesions of the oral cavity (31 cases, 53%) had a high EGFR score (23 cases, 74.2%). A statistically significant correlation was found between tumor grade and EGFR score (p = 0.03338).

Conclusion This study from eastern region of India reveals unique characteristics of EGFR expression in SCC of the oral cavity and adjacent sites.

Time series expression pattern of key genes reveals the molecular process of esophageal cancer

Background: Esophageal cancer is one of the most poorly diagnosed and fatal cancers in the world. Although a series of studies on esophageal cancer have been reported, the molecular pathogenesis of the disease is still elusive. Aim: To investigate the molecular process of esophageal cancer comprehensively and deeply. Methods: Differential expression analysis was performed to identify differentially expressed genes (DEGs) in different stages of esophageal cancer. Then exacting gene interaction modules and hub genes were identified in module interaction network. Further, though survival analysis, methylation analysis, pivot analysis, and enrichment analysis, some important molecules and related function or pathway were identified to elucidate potential mechanism in esophageal cancer. Results: A total of 7457 DEGs and 14 gene interaction modules were identified. These module genes were significantly involved in the positive regulation of protein transport, gastric acid secretion, insulin-like growth factor receptor binding and other biological processes (BPs), as well as p53 signaling pathway, ERBB signaling pathway and epidermal growth factor receptor (EGFR) signaling pathway. Then, transcription factors (TFs) (including HIF1A) and ncRNAs (including CRNDE and hsa-mir-330-3p) significantly regulate dysfunction modules were identified. Further, survival analysis showed that GNGT2 was closely related to survival of esophageal cancer. And DEGs with strong methylation regulation ability were identified, including SST and SH3GL2. Conclusion: These works not only help us to reveal the potential regulatory factors in the development of disease, but also deepen our understanding of its deterioration mechanism.

Differential Wnt-β- catenin pathway activation in HPV positive and negative oral epithelium is transmitted during head and neck tumorigenesis: clinical implications

The aim of this study is to understand the association of HPV infection and wnt-β-catenin self-renewal pathway in development of head and neck squamous cell carcinoma (HNSCC). For this reason, the molecular profiles (methylation/deletion/expression) of antagonists (SFRP1/2 and DKK1), agonists (FZD7 and LRP6) and effector protein β-catenin of the pathway were analyzed in HPV positive/negative oral epithelium at first, followed by its changes during development of the tumor along with correlations with different clinico-pathological parameters. HPV infection alone or in combination with tobacco habit could activate p- β-catenin expression in basal/parabasal layers of oral epithelium through high expression of FZD7 and significant down regulation of SFRP1/2 through promoter hypermethylation due to over expression of DNMT1 with ubiquitous down regulation of DKK1 and up-regulation of LRP6. This phenomenon has been seen in respective HPV positive and negative HNSCC tumors with additional deletion/microsatellite size alterations in the antagonists. Overall alterations (methylation/deletion) of SFRP1/2, DKK1 gradually increased from Group I (HPV-/Tobacco-) to Group IV(HPV+/Tobacco+) tumors, leading to the worst prognosis of the patients. Thus, the transmission of differentially activated wnt-β-catenin pathway from HPV positive/negative basal/parabasal layers of oral epithelium to HNSCC tumors determines differences in molecular pathogenesis of the disease.

Comprehensive multi-omics analysis identified core molecular processes in esophageal cancer and revealed GNGT2 as a potential prognostic marker

BACKGROUND

Esophageal cancer is one of the most poorly diagnosed and fatal cancers in the world. Although a series of studies on esophageal cancer have been reported, the molecular pathogenesis of the disease remains elusive.

AIM

To investigate comprehensively the molecular process of esophageal cancer.

METHODS

Differential expression analysis was performed to identify differentially expressed genes (DEGs) in different stages of esophageal cancer from The Cancer Genome Atlas data. Exacting gene interaction modules were generated, and hub genes in the module interaction network were found. Further, through survival analysis, methylation analysis, pivot analysis, and enrichment analysis, some important molecules and related functions/pathways were identified to elucidate potential mechanisms in esophageal cancer.

RESULTS

A total of 7457 DEGs and 14 gene interaction modules were identified. These module genes were significantly involved in the positive regulation of protein transport, gastric acid secretion, insulin-like growth factor receptor binding, and other biological processes as well as p53 signaling pathway, epidermal growth factor signaling pathway, and epidermal growth factor receptor signaling pathway. Transcription factors (including hypoxia inducible factor 1A) and non-coding RNAs (including colorectal differentially expressed and hsa-miR-330-3p) that significantly regulate dysfunction modules were identified. Survival analysis showed that G protein subunit gamma transducin 2 (GNGT2) was closely related to survival of esophageal cancer. DEGs with strong methylation regulation ability were identified, including SST and SH3GL2. Furthermore, the expression of GNGT2 was evaluated by quantitative real time polymerase chain reaction, and the results showed that GNGT2 expression was significantly upregulated in esophageal cancer patient samples and cell lines. Moreover, cell counting kit-8 assay revealed that GNGT2 could promote the proliferation of esophageal cancer cell lines.

CONCLUSION

This study not only revealed the potential regulatory factors involved in the development of esophageal cancer but also deepens our understanding of its underlying mechanism.

Genome-Wide Analysis of Head and Neck Squamous Cell Carcinomas Reveals HPV, TP53, Smoking and Alcohol-Related Allele-Based Acquired Uniparental Disomy Genomic Alterations

Smoking and alcohol intake are major risk factors in head and neck squamous cell carcinomas (HNSCCs). Although the link between TP53 mutation and smoking has been well established, very little is known about the link between acquired uniparental disomy (aUPD) and smoking and/or alcohol consumption or other clinical characteristics. We used TCGA genomic data to investigate whether smoking, alcohol intake, clinical and demographic variables, HPV status and TP53 mutation are associated with aUPD at specific chromosomal regions. In multivariate analysis, we found association between aUPD regions and risk factors and clinical variables of disease. aUPD regions on chromosome 4q, 5q, 9p, 9q, 13q, 17p and CDKN2A occurred significantly more often in patients with TP53-mutated HNSCC than in those with wild-type HNSCC, while aUPD regions on chromosome 9p and at CDKN2A were significantly more frequent in females than in males. Besides, aUPD occurred more frequent in HPV-positive than in HPV-negative samples with all HNSCC and larynx cancers on chromosome 9q 15q and 17p. Moreover, aUPD on CDKN2A region occurred more often in alcohol drinkers than nondrinkers in patients with all HNSCC and oral cavity cancers, while aUPD region on chromosome 5q occurred less in alcohol drinkers than nondrinkers in patients with all HNSCC and oral cavity cancers. Similarly, aUPD region on chromosome 5q occurred less in smokers than nonsmokers in patients with all HNSCC and oral cavity cancers. In conclusion, aUPD regions are not random, and certain regions are associated with risk factors for disease, and with TP53 mutation status.

Competition between TIAM1 and Membranes Balances Endophilin A3 Activity in Cancer Metastasis

Normal cells acquire aggressive behavior by modifying signaling pathways. For instance, alteration of endocytosis profoundly impacts both proliferation and migration during tumorigenesis. Here we investigate the mechanisms that enable the endocytic machinery to coordinate these processes. We show that a membrane curvature-sensing protein, endophilin A3, promotes growth and migration of colon cancer cells through two competing mechanisms: an endocytosis pathway that is required for proliferation and a GTPase regulatory pathway that controls cell motility. EndoA3 stimulates cell migration by binding the Rac GEF TIAM1 leading to activation of small GTPases. Competing interactions of EndoA3 with membrane versus TIAM1 modulate hyperproliferative and metastatic phenotypes. Disruption of EndoA3-membrane interactions stimulates TIAM1 and small GTPases in vitro, and further promotes pro-metastatic phenotypes in vivo. Together, these results uncover a coupling mechanism, by which EndoA3 promotes growth and migration of colon cancers, by linking membrane dynamics to GTPase regulation.

Differential transmission of the molecular signature of RBSP3, LIMD1 and CDC25A in basal/ parabasal versus spinous of normal epithelium during head and neck tumorigenesis: A mechanistic study

Head and neck squamous cell carcinoma (HNSCC) is a global disease and mortality burden, necessitating the elucidation of its molecular progression for effective disease management. The study aims to understand the molecular profile of three candidate cell cycle regulatory genes, RBSP3, LIMD1 and CDC25A in the basal/ parabasal versus spinous layer of normal oral epithelium and during head and neck tumorigenesis. Immunohistochemical expression and promoter methylation was used to determine the molecular signature in normal oral epithelium. The mechanism of alteration transmission of this profile during tumorigenesis was then explored through additional deletion and mutation in HPV/ tobacco etiological groups, followed byclinico-pathological correlation. In basal/parabasal layer, the molecular signature of the genes was low protein expression/ high promoter methylation of RBSP3, high expression/ low methylation of LIMD1 and high expression of CDC25A. Dysplastic epithelium maintained the signature of RBSP3 through high methylation/ additional deletion with loss of the signatures of LIMD1 and CDC25A via deletion/ additional methylation. Similarly, maintenance and / or loss of signature in invasive tumors was by recurrent deletion/ methylation. Thus, differential patterns of alteration of the genes might be pre-requisite for the development of dysplastic and invasive lesions. Etiological factors played a key role in promoting genetic alterations and determining prognosis. Tobacco negative HNSCC patients had significantly lower alterations of LIMD1 and CDC25A, along with better survival among tobacco negative/ HPV positive patients. Our data suggests the necessity for perturbation of normal molecular profile of RBSP3, LIMD1 and CDC25A in conjunction with etiological factors for head and neck tumorigenesis, implying their diagnostic and prognostic significance.

Diagnostic accuracy of DNA methylation for head and neck cancer varies by sample type and number of markers tested

Abnormal methylation of certain cancer related genes strongly predicts a diagnosis of head and neck cancer (HNC), while the predictive power of methylation of other DNA markers for HNC remains unclear. To systemically assess the diagnostic value of DNA methylation patterns for HNC and the effect of methylation platform techniques and sample types, we performed a PubMed search for studies of the correlation between DNA methylation and HNC completed before July 2016, and extracted the sensitivity and specificity for methylated biomarkers. Across these studies, DNA methylation showed high sensitivity for diagnosing HNC in solid tissue (0.57), and high specificity in saliva (0.89). Area under the curve (AUC) from summary receiver operating characteristic (SROC) curves revealed that DNA methylation had more diagnostic power in solid tissue (AUC = 0.82) than saliva (AUC = 0.80) or blood (AUC = 0.77). Combinations of multiple methylated genes were more sensitive diagnostic markers than single methylated genes. Our results suggest that the diagnostic accuracy of methylated biomarkers for HNC varied by sample type and were most accurate when results from multiple sample types were considered.

Human papilloma virus (HPV) infection leads to the development of head and neck lesions but offers better prognosis in malignant Indian patients

Head and neck cancers constitute a multifactorial global disease burden and are associated with human papilloma virus (HPV) as a possible risk factor. The aim of the study is to understand the relationship between HPV and the development of head and neck lesions in Indian patients. To this end, frequency of HPV was assessed in relation to different demographic and etiological features and correlated with patient survival. The prevalence of HPV significantly increased from mild dysplastic lesions (43.6%) to head and neck squamous cell carcinoma (HNSCC) stage IV (68.5%) with HPV 16 being pre-dominant in both dysplasia (43.8%) and HNSCC (61.5%). Similar trend was observed in increasing grades of the tumour. In invasive lesions, patients aged below the median age of onset showed significantly higher occurrence of HPV than those above it. Patients harbouring HPV showed a significantly better survival irrespective of age of onset. Likewise, better survival was observed in tobacco habit negative/HPV-positive patients, and as reflected in both univariate and multivariate analysis. Majority of the HPV 16-positive samples showed moderate/high nuclear expression of HPV E6 and E7 proteins in tumours and respective basal layer of adjacent normal tissues. Thus, our data indicate that frequent HPV infection, along with tobacco habit, is a pre-requisite factor for the development of HNSCC of Indian patients but offers a better survival even during tobacco usage, implicating its diagnostic and prognostic importance.

Association of P16-RBSP3 inactivation with phosphorylated RB1 overexpression in basal-parabasal layers of normal cervix unchanged during CACX development

To understand the molecular mechanism of RB1 phosphorylation in basal-parabasal layers of normal cervix and during cervical cancer (CACX) development, we analyzed the alterations (expression/methylation/deletion/mutation) of RB1/phosphorylated RB1 (p-RB1) (ser807/811 and ser567) and two RB1 phosphorylation inhibitors, P16 and RBSP3, in disease-free normal cervical epithelium (n = 9), adjacent normal cervical epithelium of tumors (n = 70), cervical intraepithelial neoplasia (CIN; n = 28), CACX (n = 102) samples and two CACX cell lines. Immunohistochemical analysis revealed high/medium expression of RB1/p-RB1 (ser807/811 and ser567) and low expression of P16 and RBSP3 in proliferating basal-parabasal layers of majority of normal cervical epitheliums, irrespective of HPV16 infection. Interestingly, 35-52% samples showed high/medium expression of P16 in basal-parabasal layers of normal and had significant association with deleterious non-synonimous SNPs of P16. Methylation of P16 and RBSP3 in basal-parabasal layers of normal cervix (32 and 62%, respectively) showed concordance with their respective expressions in basal-parabasal layers. The methylation frequency of P16 and RBSP3 in basal-parabasal layers of normal did not change significantly in CIN and CACX. The deletion frequency of P16 and RB1 increased significantly with CACX progression. While, deletion of RBSP3 was high in CIN and comparable during CACX progression. P16 showed scattered and infrequent mutation in CACX. The alteration of P16 and RBSP3 was synergistic and showed association with overexpression of p-RB1 in tumors and associated with poor prognosis of patients. Thus, our data suggest that overexpression of p-RB1 in basal-parabasal layers of normal cervical epithelium was due to methylation/low functional-linked non-synonimous SNPs of P16 and RBSP3. This pattern was maintained during cervical carcinogenesis by additional deletion/mutation.

DNA methylation markers for oral pre-cancer progression: A critical review

Although oral cancers are generally preceded by a well-established pre-cancerous stage, there is a lack of well-defined clinical and morphological criteria to detect and signal progression from pre-cancer to malignant tumours. We conducted a critical review to summarize the evidence regarding aberrant DNA methylation patterns as a potential diagnostic biomarker predicting progression. We identified all relevant human studies published in English prior to 30th April 2015 that examined DNA methylation (%) in oral pre-cancer by searching PubMed, Web-of-Science and Embase databases using combined key-searches. Twenty-one studies (18-cross-sectional; 3-longitudinal) were eligible for inclusion in the review, with sample sizes ranging from 4 to 156 affected cases. Eligible studies examined promoter region hyper-methylation of tumour suppressor genes in pathways including cell-cycle-control (n=15), DNA-repair (n=7), cell-cycle-signalling (n=4) and apoptosis (n=3). Hyper-methylated loci reported in three or more studies included p16, p14, MGMT and DAPK. Two longitudinal studies reported greater p16 hyper-methylation in pre-cancerous lesions transformed to malignancy compared to lesions that regressed (57-63.6% versus 8-32.1%; p<0.01). The one study that explored epigenome-wide methylation patterns reported three novel hyper-methylated loci (TRHDE; ZNF454; KCNAB3). The majority of reviewed studies were small, cross-sectional studies with poorly defined control groups and lacking validation. Whilst limitations in sample size and study design preclude definitive conclusions, current evidence suggests a potential utility of DNA methylation patterns as a diagnostic biomarker for oral pre-cancer progression. Robust studies such as large epigenome-wide methylation explorations of oral pre-cancer with longitudinal tracking are needed to validate the currently reported signals and identify new risk-loci and the biological pathways of disease progression.

Distinct Functions of Endophilin Isoforms in Synaptic Vesicle Endocytosis

Endophilin isoforms perform distinct characteristics in their interactions with N-type Ca²⁺ channels and dynamin. However, precise functional differences for the endophilin isoforms on synaptic vesicle (SV) endocytosis remain unknown. By coupling RNA interference and electrophysiological recording techniques in cultured rat hippocampal neurons, we investigated the functional differences of three isoforms of endophilin in SV endocytosis. The results showed that the amplitude of normalized evoked excitatory postsynaptic currents in endophilin1 knockdown neurons decreased significantly for both single train and multiple train stimulations. Similar results were found using endophilin2 knockdown neurons, whereas endophilin3 siRNA exhibited no change compared with control neurons. Endophilin1 and endophilin2 affected SV endocytosis, but the effect of endophilin1 and endophilin2 double knockdown was not different from that of either knockdown alone. This result suggested that endophilin1 and endophilin2 functioned together but not independently during SV endocytosis. Taken together, our results indicate that SV endocytosis is sustained by endophilin1 and endophilin2 isoforms, but not by endophilin3, in primary cultured hippocampal neurons.

SNP rs1049430 in the 3'-UTR of SH3GL2 regulates its expression: Clinical and prognostic implications in head and neck squamous cell carcinoma

Single nucleotide polymorphisms (SNPs) in the 3'-UTR region are emerging cis-regulatory factors associated with the occurrences of several human diseases. SH3GL2, which is located at chromosome 9p21-22, is associated with hyperplastic/mildly dysplastic lesions of the head and neck and has a long 3'-UTR with multiple SNPs. The aim of the present study was to determine the susceptible allele(s) in the 3'-UTR SNPs of SH3GL2 in head and neck squamous cell carcinoma (HNSCC). First, we screened the genotypes of all SNPs located in the 3'-UTR of SH3GL2 in 110 controls and 147 cases in Indian populations by sequencing. A SNP (rs1049430:>G/T) that showed only heterozygosity was further confirmed by genotyping with an Illumina GoldenGate platform in 530 controls and 764 cases. Genotype-specific survival analysis of the HNSCC patients was performed. In addition, genotype-specific mRNA stability, isoform expression and protein expression were analyzed. SNP rs1049430 was not associated with disease occurrence, but it was associated with poor patient outcome. The G allele was associated with decreased SH3GL2 mRNA stability, differential splicing and low protein expression. Thus, our data demonstrate that the presence of the susceptible G allele in SNP rs1049430 is associated with the inactivation of SH3GL2 and could be used as a prognostic marker of HNSCC.

Association between P16INK4a promoter methylation and HNSCC: a meta-analysis of 21 published studies

Background

The p16^INK4a is an important tumor suppressor gene (TSG) and aberrant methylation of promoter is known to be a major inactivation mechanism of the tumor suppressor and tumor-related genes. Aberrant TSG methylation was considered an important epigenetic silencing mechanism in the progression of head and neck squamous cell carcinoma (HNSCC). However, some studies have reported differences in the methylation frequencies of P^16INK4a promoter between cancer and the corresponding control group. Therefore, we conducted a meta-analysis to better identify the association.

Methods

PubMed, Ovid, ISI Web of Science, and EMBASE were searched to identify eligible studies to evaluate the association of p16^INK4a promoter methylation and HNSCC. Odds ratio (ORs) and 95% confidence intervals (95%CI) were calculated to evaluate the strength of association between p16^INK4a promoter methylation and HNSCC.

Results

A total of twenty-one studies with 1155 cases and 1017 controls were included in the meta-analysis. The frequencies of p16^INK4a promoter methylation in the cancer group were significantly higher than those in the control group (cancer group: median: 46.67%, range = 7.84%-95.12%; control group: median: 18.37%, range = 0–83.33%; respectively). The pooled odds ratio was 3.37 (95%CI = 2.32–4.90) in the cancer group versus the corresponding control group under the random-effects model.

Conclusion

This meta-analysis of 21 published studies identified that aberrant methylation of p16^INK4a promoter was found to be significantly associated with HNSCC.

Frequent inactivation of SLIT2 and ROBO1 signaling in head and neck lesions: clinical and prognostic implications

OBJECTIVE

The protein SLIT2 and its receptor ROBO1 regulate different cellular processes, such as proliferation, apoptosis, and migration. In this study our aim is to understand the alterations of these genes during development of head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

First, molecular alterations of the genes were analyzed in 30 dysplastic lesions, 128 primary HNSCC samples, and 1 HNSCC cell line. Then alterations were correlated with mRNA expression (n = 22) and protein expression (n = 29). Finally, the alterations were correlated with different clinicopathologic parameters and clinical outcomes of the patients.

RESULTS

ROBO1 had a comparatively high frequency of deletion (28.5%-54.2%) from dysplastic lesions and subsequent clinical stages than did SLIT2 (16.6-27%). On the contrary, SLIT2 had a high frequency (56.6%-81.2%) of promoter methylation from dysplastic lesions onward compared with ROBO1 (20%-32.8%). Interestingly, alterations of SLIT2 and ROBO1 were high in dysplastic lesions (80%), followed by comparable frequencies (92.5%-95.3%) in subsequent stages of tumor. Alterations of these genes showed concordance with their mRNA/protein expression and significant association with poor patient outcome.

CONCLUSIONS

Our data suggest that inactivation of SLIT2 and/or ROBO1 is one of the early events in development of dysplastic lesions of head and neck and has prognostic importance.

Epigenetic pathogenesis of human papillomavirus in upper aerodigestive tract cancers

Human papillomavirus (HPV) has been recently associated with squamous cell carcinoma of upper aerodigestive tract (SCC of UADT), but its possible role in promoting aberrant methylation in these tumors has largely remained unexplored. Herein, we investigated the association of HPV with aberrant methylation in tumor-related genes/loci consisting of the classical CpG Island Methylator Phenotype (CIMP) panel markers (p16, MLH1, MINT1, MINT2, and MINT31) and other frequently methylated cancer-related genes (DAPK1, GSTP1, BRCA1, ECAD, and RASSF1) and survival of UDAT cancers. The study includes 219 SCC of UADT patients from different hospitals of Northeast India. Detection of HPV and aberrant promoter methylation was performed by PCR and Methylation Specific PCR respectively. Association study was conducted by Logistic regression analysis and overall survival analysis was done by Kaplan-Meier plot. HPV was detected in 37% of cases, with HPV-18 as the major high-risk sub-type. Although HPV presence did not seem to affect survival in overall UADT cancers, but was associated with a favourable prognosis in head and neck squamous cell carcinoma. Hierarchical clustering revealed three distinct clusters with different methylation profile and HPV presence. Among these, the CIMP-high subgroup exhibited the highest HPV positive cases (66%). Furthermore, multivariate analysis revealed a strong synergistic association of HPV and tobacco towards modulating promoter hypermethylation in UADT cancer (OR = 27.50 [95% CI = 11.51-88.03] for CIMP-high vs. CIMP-low). The present study proposes a potential role of HPV in impelling aberrant methylation in specific tumor related loci, which might contribute in the initiation and progression of SCC of UADT.

Increased oxidative DNA damage and decreased expression of base excision repair proteins in airway epithelial cells of women who cook with biomass fuels

To investigate whether biomass burning causes oxidative DNA damage and alters the expression of DNA base excision repair (BER) proteins in airway cells, sputum samples were collected from 80 premenopausal rural biomass-users and 70 age-matched control women who cooked with liquefied petroleum gas. Compared with control the airway cells of biomass-users showed increased DNA damage in alkaline comet assay. Biomass-users showed higher percentage of cells expressing oxidative DNA damage marker 8-oxoguanine and lower percentages of BER proteins OGG1 and APE1 by immunocytochemical staining. Reactive oxygen species (ROS) generation was doubled and level of superoxide dismutase was depleted significantly among biomass-users. The concentrations of particulate matters were higher in biomass-using households which positively correlated with ROS generation and negatively with BER proteins expressions. ROS generation was positively correlated with 8-oxoguanine and negatively with BER proteins suggesting cooking with biomass is a risk for genotoxicity among rural women in their child-bearing age.

Reduction of DNA mismatch repair protein expression in airway epithelial cells of premenopausal women chronically exposed to biomass smoke

Biomass burning is a major source of indoor air pollution in rural India. This study examined whether chronic inhalation of biomass smoke causes change in the DNA mismatch repair (MMR) pathway in the airway cells. For this, airway cells exfoliated in sputum were collected from 72 premenopausal nonsmoking rural women (median age 34 years) who cooked with biomass (wood, dung, crop residues) and 68 control women who cooked with cleaner fuel liquefied petroleum gas (LPG) for the past 5 years or more. The levels of particulate matters with diameters less than 10 and 2.5 μm (PM10 and PM2.5) in indoor air were measured by real-time aerosol monitor. Benzene exposure was monitored by measuring trans,trans-muconic acid (t,t-MA) in urine by high-performance liquid chromatography with ultraviolet detector. Generation of reactive oxygen species (ROS) and level of superoxide dismutase (SOD) in airway cells were measured by flow cytometry and spectrophotometry, respectively. Immunocytochemical assay revealed lower percentage of airway epithelial cells expressing MMR proteins mutL homolog 1 (MLH1) and mutS homolog 2 (MSH2) in biomass-using women compared to LPG-using controls. Women who cooked with biomass had 6.7 times higher level of urinary t,t-MA, twofold increase in ROS generation, and 31 % depletion of SOD. Indoor air of biomass-using households had three times more particulate matters than that of controls. ROS, urinary t,t-MA, and particulate pollution in biomass-using kitchen had negative correlation, while SOD showed positive correlation with MSH2 and MLH1 expression. It appears that chronic exposure to biomass smoke reduces MMR response in airway epithelial cells, and oxidative stress plays an important role in the process.

Loss of Sh3gl2/endophilin A1 is a common event in urothelial carcinoma that promotes malignant behavior

Urothelial carcinoma (UC) causes substantial morbidity and mortality worldwide. However, the molecular mechanisms underlying urothelial cancer development and tumor progression are still largely unknown. Using informatics analysis, we identified Sh3gl2 (endophilin A1) as a bladder urothelium-enriched transcript. The gene encoding Sh3gl2 is located on chromosome 9p, a region frequently altered in UC. Sh3gl2 is known to regulate endocytosis of receptor tyrosine kinases implicated in oncogenesis, such as the epidermal growth factor receptor (EGFR) and c-Met. However, its role in UC pathogenesis is unknown. Informatics analysis of expression profiles as well as immunohistochemical staining of tissue microarrays revealed Sh3gl2 expression to be decreased in UC specimens compared to nontumor tissues. Loss of Sh3gl2 was associated with increasing tumor grade and with muscle invasion, which is a reliable predictor of metastatic disease and cancer-derived mortality. Sh3gl2 expression was undetectable in 19 of 20 human UC cell lines but preserved in the low-grade cell line RT4. Stable silencing of Sh3gl2 in RT4 cells by RNA interference 1) enhanced proliferation and colony formation in vitro, 2) inhibited EGF-induced EGFR internalization and increased EGFR activation, 3) stimulated phosphorylation of Src family kinases and STAT3, and 4) promoted growth of RT4 xenografts in subrenal capsule tissue recombination experiments. Conversely, forced re-expression of Sh3gl2 in T24 cells and silenced RT4 clones attenuated oncogenic behaviors, including growth and migration. Together, these findings identify loss of Sh3gl2 as a frequent event in UC development that promotes disease progression.

Potentially functional variants of p14ARF are associated with HPV-positive oropharyngeal cancer patients and survival after definitive chemoradiotherapy

Since p14 (ARF) and human papillomavirus (HPV) 16 E6/E7 oncoproteins are important regulators participating in the p53/Rb pathways, genetic variations of p14 (ARF) may modify tumor HPV16 status and survival of HPV16-positive squamous cell carcinoma of the oropharynx (SCCOP) patients. We determined tumor HPV16 status and expression of p14/p53 and genotyped p14 (ARF) -rs3731217 and -rs3088440 polymorphisms in 552 incident SCCOP patients. We found that patients having variant genotypes for each p14 (ARF) polymorphism were approximately two or three times as likely to have HPV16-positive tumors compared with patients with corresponding common homozygous genotype, and such an association was particularly pronounced in patients with variant genotypes of both polymorphisms. After definitive chemoradiotherapy, patients having p14 (ARF) rs3731217 TG/GG variant genotypes had significantly better overall, disease-specific and disease-free survival than those having TT genotype, respectively. Multivariable analysis found that patients with p14 (ARF) -rs3731217 TT genotype had an ~7-, 11- and 3-fold increased risk for death overall, death due to SCCOP and recurrence than those with TG/GG variant genotypes, respectively. Furthermore, such significantly prognostic effect was also found when survival analysis was limited to HPV16-positive patients. Additionally, potentially functional relevance of the two variants was characterized to explore the genotype-phenotype correlation. Our findings indicate p14 (ARF) variants may predict tumor HPV16-positive SCCOP patients and survival.

Overexpression of EGFR in head and neck squamous cell carcinoma is associated with inactivation of SH3GL2 and CDC25A genes

The aim of this study is to understand the mechanism of EGFR overexpression in head and neck squamous cell carcinoma (HNSCC). For this reason, expression/mutation of EGFR were analyzed in 30 dysplastic head and neck lesions and 148 HNSCC samples of Indian patients along with 3 HNSCC cell lines. In addition, deletion/methylation/mutation/expression of SH3GL2 (associated with EGFR degradation) and CDC25A (associated with dephosphorylation of EGFR) were analyzed in the same set of samples. Our study revealed high frequency of EGFR overexpression (66–84%), low frequency of gene amplification (10–32.5%) and absence of functional mutation in the dysplastic lesions and HNSCC samples. No correlation was found between protein overexpression and mRNA expression/gene amplification status of EGFR. On the other hand, frequent alterations (deletion/methylation) of SH3GL2 (63–77%) and CDC25A (37–64%) were seen in the dysplastic and HNSCC samples. Two novel single nucleotide polymorphism (SNPs) were found in the promoter region of SH3GL2. Reduced expression of these genes showed concordance with their alterations. Overexpression of EGFR and p-EGFR were significantly associated with reduced expression and alterations of SH3GL2 and CDC25A respectively. In-vitro demethylation experiment by 5-aza-2′-deoxycytidine (5-aza-dC) showed upregulation of SH3GL2 and CDC25A and downregulation of EGFR expression in Hep2 cell line. Poor patient outcome was predicted in the cases with alterations of SH3GL2 and CDC25A in presence of human papilloma virus (HPV) infection. Also, low SH3GL2 and high EGFR expression was a predictor of poor patient survival. Thus, our data suggests that overexpression of EGFR due to its reduced degradation and dephosphorylation is needed for development of HNSCC.

Epigenetic regulation of the X-linked tumour suppressors BEX1 and LDOC1 in oral squamous cell carcinoma

The strong associations between oral squamous cell carcinoma (OSCC) and dietary habits such as alcohol consumption (A), betel quid chewing (B) and cigarette smoking (C) and its predominance in men have been well documented; however, systemic analysis of OSCC is limited. Our study applied high-throughput screening methods to identify causative epigenetic targets in a cohort of men with ABC-associated OSCC. We identified BEX1 and LDOC1 as two epigenetically silenced X-linked tumour suppressors and demonstrated a functional link between the transcription of BEX1 and LDOC1 and promoter hypermethylation. Methylation of the BEX1 and LDOC1 promoters was associated significantly (p < 0.0001) with OSCC and were detected in 75% (42/56) and 89% (50/56) of the samples, respectively. We observed concordant increases in the methylation of both genes in 71% (40/56) of the tumours, and potent in vitro and in vivo growth inhibitory effects in OSCC cells ectopically expressing BEX1 and/or LDOC1. Restored expression of BEX1 and LDOC1 suppressed the nuclear factor-κB (NF-κB) signalling pathway, which is the most frequently hyperactivated signalling pathway in OSCC. This suppression might result from decreased p50 and p65 expression. These findings suggest that silencing of BEX1 and LDOC1 by promoter hypermethylation might represent a critical event in the molecular pathogenesis of OSCC and account for the oncogenic effects of ABC exposure and the male predominance of OSCC occurrence. Microarray data are available in the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo/)

MicroRNA-330 is an oncogenic factor in glioblastoma cells by regulating SH3GL2 gene

MicroRNAs have recently emerged as key regulators of cancers. This study was therefore conducted to investigate the role of miR-330 in biological behaviors of human glioblastoma U87 and U251 cell lines and its molecular mechanism. SH3GL2 gene was identified as the target of miR-330. MiR-330 overexpression was established by transfecting miR-330 precursor into U87 and U251 cells, and its effects on proliferation, migration, invasion, cell cycle and apoptosis were studied. Overexpression of miR-330 can enhance cellular proliferation, promote migration and invasion, activate cell cycle and also inhibit apoptosis in U87 and U251 cells. Collectively, these above-mentioned results suggest that miRNA-330 plays an oncogenic role in human glioblastoma by regulating SH3GL2 gene and might be a new therapeutic target of human glioblastoma.

SH3GL2 is frequently deleted in non-small cell lung cancer and downregulates tumor growth by modulating EGFR signaling

The purpose of this study was to identify key genetic pathways involved in non-small cell lung cancer (NSCLC) and understand their role in tumor progression. We performed a genome wide scanning using paired tumors and corresponding 16 mucosal biopsies from four follow-up lung cancer patients on Affymetrix 250K-NSpI array platform. We found that a single gene SH3GL2 located on human chromosome 9p22 was most frequently deleted in all the tumors and corresponding mucosal biopsies. We further validated the alteration pattern of SH3GL2 in a substantial number of primary NSCLC tumors at DNA and protein level. We also overexpressed wild-type SH3GL2 in three NSCLC cell lines to understand its role in NSCLC progression. Validation in 116 primary NSCLC tumors confirmed frequent loss of heterozygosity of SH3GL2 in overall 51 % (49/97) of the informative cases. We found significantly low (p = 0.0015) SH3GL2 protein expression in 71 % (43/60) primary tumors. Forced overexpression of wild-type (wt) SH3GL2 in three NSCLC cell lines resulted in a marked reduction of active epidermal growth factor receptor (EGFR) expression and an increase in EGFR internalization and degradation. Significantly decreased in vitro (p = 0.0015-0.030) and in vivo (p = 0.016) cellular growth, invasion (p = 0.029-0.049), and colony formation (p = 0.023-0.039) were also evident in the wt-SH3GL2-transfected cells accompanied by markedly low expression of activated AKT(Ser(473)), STAT3 (Tyr(705)), and PI3K. Downregulation of SH3GL2 interactor USP9X and activated ß-catenin was also evident in the SH3GL2-transfected cells. Our results indicate that SH3GL2 is frequently deleted in NSCLC and regulates cellular growth and invasion by modulating EGFR function.

Mantle cell lymphoma displays a homogenous methylation profile: a comparative analysis with chronic lymphocytic leukemia

Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) are mature CD5(+) B-cell malignancies with different biological/clinical characteristics. We recently reported an association between different prognostic subgroups of CLL (i.e., IGHV mutated and unmutated) and genomic methylation pattern. However, the relationship between DNA methylation and prognostic markers, such as the proliferation gene expression signature, has not been investigated in MCL. We applied high-resolution methylation microarrays (27,578 CpG sites) to assess the global DNA methylation profiles in 20 MCL (10 each with high/low proliferation signature) and 30 CLL (15 poor-prognostic IGHV unmutated subset #1 and 15 good-prognostic IGHV mutated subset #4) samples. Notably, MCL and each CLL subset displayed distinct genomic methylation profiles. After unsupervised hierarchical clustering, 17/20 MCL cases formed a cluster separate from CLL, while CLL subsets #1 and #4 formed subclusters. Surprisingly, few differentially methylated genes (n = 6) were identified between high vs. low proliferation MCL. In contrast, distinct methylation profiles were demonstrated for MCL and CLL. Importantly, certain functional classes of genes were preferentially methylated in either disease. For instance, developmental genes, in particular homeobox transcription factor genes (e.g., HLXB9, HOXA13), were more highly methylated in MCL, whereas apoptosis-related genes were enriched among targets methylated in CLL (e.g., CYFIP2, NR4A1). Results were validated using pyrosequencing, RQ-PCR and reexpression of specific genes. In summary, the methylation profile of MCL was homogeneous and no correlation with the proliferation signature was observed. Compared to CLL, however, marked differences were discovered such as the preferential methylation of homeobox genes in MCL.

Human papillomavirus, smoking, and head and neck cancer

AIMS

Smoking and human papillomavirus (HPV) are both distinct risk factors for head and neck cancer, but the nature of interaction between these 2 risk factors in the development of head and neck cancer remains unclear. The purpose of this review is to determine the potential effect of smoking in causation of HPV-related head and neck carcinoma.

METHOD

A literature search was carried out using the keywords human papillomavirus, head and neck cancer, smoking, tobacco, and cervical cancer. The English-language articles, references, and other relevant studies evaluating the association of smoking, HPV, and risk of head and neck cancer were collected and analyzed.

CONCLUSION

Overall, our review points to smoking tobacco posing an additional risk for development of head and neck cancer in the presence of HPV infection. This is consistent with available laboratory data that show evidence of biological plausibility for interaction between smoking and progression of HPV infection to carcinogenesis. It is therefore important that cessation of smoking is promoted in smokers with HPV infection.

An examination of male and female odds ratios by BMI, cigarette smoking, and alcohol consumption for cancers of the oral cavity, pharynx, and larynx in pooled data from 15 case-control studies

BACKGROUND

Greater tobacco smoking and alcohol consumption and lower body mass index (BMI) increase odds ratios (OR) for oral cavity, oropharyngeal, hypopharyngeal, and laryngeal cancers; however, there are no comprehensive sex-specific comparisons of ORs for these factors.

METHODS

We analyzed 2,441 oral cavity (925 women and 1,516 men), 2,297 oropharynx (564 women and 1,733 men), 508 hypopharynx (96 women and 412 men), and 1,740 larynx (237 women and 1,503 men) cases from the INHANCE consortium of 15 head and neck cancer case-control studies. Controls numbered from 7,604 to 13,829 subjects, depending on analysis. Analyses fitted linear-exponential excess ORs models.

RESULTS

ORs were increased in underweight (< 18.5 BMI) relative to normal weight (18.5-24.9) and reduced in overweight and obese categories (≥ 25 BMI) for all sites and were homogeneous by sex. ORs by smoking and drinking in women compared with men were significantly greater for oropharyngeal cancer (p < 0.01 for both factors), suggestive for hypopharyngeal cancer (p = 0.05 and p = 0.06, respectively), but homogeneous for oral cavity (p = 0.56 and p = 0.64) and laryngeal (p = 0.18 and p = 0.72) cancers.

CONCLUSIONS

The extent that OR modifications of smoking and drinking by sex for oropharyngeal and, possibly, hypopharyngeal cancers represent true associations, or derive from unmeasured confounders or unobserved sex-related disease subtypes (e.g., human papillomavirus-positive oropharyngeal cancer) remains to be clarified.

p14ARF genetic polymorphisms and susceptibility to second primary malignancy in patients with index squamous cell carcinoma of the head and neck

BACKGROUND

p14(ARF) , an alternate reading frame (ARF) product of the cyclin-dependent kinase inhibitor 2A locus, plays a critical role in crosstalk between the tumor protein 53 (p53) and retinoblastoma (Rb) pathways and in cellular anticancer mechanisms. Therefore, the authors of this report investigated the association between single nucleotide polymorphisms (SNPs) of the p14(ARF) gene and the risk of developing a second primary malignancy (SPM) after an index squamous cell carcinoma of the head and neck (SCCHN).

METHODS

The log-rank test and Cox proportional hazards models were used to assess the association of 2 p14(ARF) SNPs (reference SNP [rs]3731217 and rs3088440) with SPM-free survival and with the risk of developing an SPM among 1287 patients who had SCCHN.

RESULTS

Patients with either p14(ARF) variant genotypes of the 2 polymorphisms had a significantly reduced SPM-free survival compared with patients with no variant genotypes (log-rank test; P = .006). Compared with the p14(ARF) thymine-thymine (TT) and guanine-guanine (GG) genotypes, the variant genotypes of p14(ARF) TG/GG and guanine-adenine (GA)/AA were associated with a significantly moderately increased risk of developing an SPM (p14(ARF) rs3731217: adjusted hazard ratio [aHR], 1.48; 95% confidence interval [CI], 1.00-2.19; p14(ARF) rs3088440: aHR, 1.61; 95% CI, 1.07-2.43). Moreover, after combining the variant genotypes of the 2 SNPs, patients who had variant genotypes were at significantly greater risk of developing an SPM compared with patients who had no variant genotypes (aHR, 3.07; 95% CI, 1.54-6.12), and the risk was particularly pronounced in several subgroups.

CONCLUSIONS

The current results suggested that there is a modestly increased risk of developing an SPM after an index SCCHN with each p14(ARF) polymorphism, and there is an even greater risk of developing an SPM for patients with combined variant genotypes of the 2 SNPs. Therefore, p14(ARF) polymorphisms may be susceptible markers of the risk of developing an SPM in patients with SCCHN.

Human papillomavirus and oropharynx cancer: biology, detection and clinical implications

OBJECTIVES

To review evidence for the role of human papillomavirus (HPV) in the etiology of oropharyngeal cancers, methods of viral detection, and the resulting clinical implications.

STUDY DESIGN

Contemporary review.

METHODS

Published journal articles identified through PubMed and conference proceedings were reviewed.

RESULTS

HPV-associated squamous cell carcinomas represent a distinct disease entity from carcinogen-associated squamous cell carcinomas. HPV oncoproteins lead to mucosal cell transformation through well-defined mechanisms. Different methods of detecting HPV exist with variable levels of sensitivity and specificity for biologically active virus. Although virus is detected in a number of head and neck subsites, studies demonstrate improved outcomes in HPV-associated carcinoma of the oropharynx only. The cell cycle regulatory protein p16 is upregulated by biologically active HPV and serves as a biomarker of improved response to therapy.

CONCLUSIONS

HPV-associated squamous cell carcinoma of the oropharynx is a biologically distinct entity from carcinogen-associated carcinoma. Understanding the molecular mechanisms behind the improved outcomes in patients with HPV-associated oropharyngeal carcinoma may lead to novel therapeutics for patients with carcinogen-associated carcinomas.

Gastrin suppresses the interdependent expression of p16 and anion exchanger 1 favoring growth inhibition of gastric cancer cells

Our previous studies demonstrated that expression and interaction of p16 with anion exchanger 1 (AE1) in gastric cancer cells is correlated with progression and shorter survival of the cancer. In this article, the effects of gastrin on p16 and AE1 and its implication in prevention and treatment of gastric cancer were studied by molecular biology techniques, animal experiment and clinical analysis. The results showed that expression of p16 in human gastric body carcinoma was downregulated along with the progression of the cancer, suggesting the reverse correlations between gastrin and p16 in vivo. Further experiments indicated that gastrin suppressed the expression of p16 via the p16 promoter and thereafter resulted in the degradation of AE1 in gastric cancer cells. Silencing of AE1 or p16 significantly inhibited the proliferation of the cancer cells. Using a xenograft tumor model in nude mice, we showed that experimental systemic hypergastrinemia induced by the administration of omeprazole led to decreased expression of AE1 and p16 as well as to a marked growth inhibition of SGC7901 tumors. It is concluded that a moderate plasma gastrin level is beneficial to the growth inhibition of gastric cancer by suppressing the expression of AE1 and p16. This finding may have an important implication for the prevention and treatment of cancers arise in the gastric antrum.

Frequent alterations of the candidate genes hMLH1, ITGA9 and RBSP3 in early dysplastic lesions of head and neck: clinical and prognostic significance

To understand the association between candidate tumor suppressor genes (TSGs) human mismatch repair protein homologue 1 (hMLH1), AP20 region gene 1 (APRG1), integrin alpha RLC (ITGA9), RB1 serine phosphates from human chromosome 3 (RBSP3) at chromosomal 3p22.3 region and development of head and neck squamous cell carcinoma (HNSCC), alterations (deletion/promoter methylation/expression) of these genes were analyzed in 65 dysplastic lesions and 84 HNSCC samples. Clinicopathological correlations were made with alterations of the genes. In HNSCC, deletion frequencies of hMLH1, ITGA9, and RBSP3 were comparatively higher than APRG1. Overall alterations (deletion/methylation) of hMLH1, ITGA9, and RBSP3 were high (45-55%) in mild dysplasia and comparable in subsequent stages of tumor progression. Quantitative RT-PCR analysis showed reduced expression of these genes in tumors concordant to their molecular alterations. An in vitro demethylation experiment by 5-aza-2'-deoxycytidine confirmed the promoter hypermethylation of RBSP3 in Hep2 and UPCI:SCC084 cell lines. Functionally less-active RBSP3A isoform was predominant in tumor tissues contrary to the adjacent normal tissue of tumors where more active RBSP3B isoform was prevalent. In immunohistochemical analysis, intense nuclear staining of hMLH1 and pRB (phosphorylated RB, the substrate of RBSP3) proteins were seen in the basal layer of normal epithelium. In tumors, concordance was seen between (i) low/intermediate level of hMLH1 expression and its molecular alterations; and (ii) intense nuclear staining of pRB and RBSP3 alterations. Poor patient outcome was seen with hMLH1 and RBSP3 alterations. Moreover, in absence of human papilloma virus (HPV) infection, tobacco-addicted patients with hMLH1, RBSP3 alterations, and nodal invasions showed poor prognosis. Thus our data suggests that dysregulation of hMLH1, ITGA9, and RBSP3 associated multiple cellular pathways are needed for the development of early dysplastic lesions of the head and neck.