Frequent promoter hypermethylation of tachykinin-1 and tachykinin receptor type 1 is a potential biomarker for head and neck cancer

Portrait of DNA methylated genes predictive of poor prognosis in head and neck cancer and the implication for targeted therapy

In addition to chronic infection with human papilloma virus (HPV) and exposure to environmental carcinogens, genetic and epigenetic factors act as major risk factors for head and neck cancer (HNC) development and progression. Here, we conducted a systematic review in order to assess whether DNA hypermethylated genes are predictive of high risk of developing HNC and/or impact on survival and outcomes in non-HPV/non-tobacco/non-alcohol associated HNC. We identified 85 studies covering 32,187 subjects where the relationship between DNA methylation, risk factors and survival outcomes were addressed. Changes in DNA hypermethylation were identified for 120 genes. Interactome analysis revealed enrichment in complex regulatory pathways that coordinate cell cycle progression (CCNA1, SFN, ATM, GADD45A, CDK2NA, TP53, RB1 and RASSF1). However, not all these genes showed significant statistical association with alcohol consumption, tobacco and/or HPV infection in the multivariate analysis. Genes with the most robust HNC risk association included TIMP3, DCC, DAPK, CDH1, CCNA1, MGMT, P16, MINT31, CD44, RARβ. From these candidates, we further validated CD44 at translational level in an independent cohort of 100 patients with tongue cancer followed-up beyond 10 years. CD44 expression was associated with high-risk of tumor recurrence and metastasis (P = 0.01) in HPV-cases. In summary, genes regulated by methylation play a modulatory function in HNC susceptibility and it represent a critical therapeutic target to manage patients with advanced disease.

The Neurokinin-1 Receptor Antagonist Aprepitant: An Intelligent Bullet against Cancer?

Neurokinin-1 receptor (NK-1R) antagonists exert antitumor action, are safe and do not cause serious side-effects. These antagonists (via the NK-1R) exert multiple actions against cancer: antiproliferative and anti-Warburg effects and apoptotic, anti-angiogenic and antimetastatic effects. These multiple effects have been shown for a broad spectrum of cancers. The drug aprepitant (an NK-1R antagonist) is currently used in clinical practice as an antiemetic. In in vivo and in vitro studies, aprepitant also showed the aforementioned multiple antitumor actions against many types of cancer. A successful combination therapy (aprepitant and radiotherapy) has recently been reported in a patient suffering from lung carcinoma: the tumor mass disappeared and side-effects were not observed. Aprepitant could be considered as an intelligent bullet against cancer. The administration of aprepitant in cancer patients to prevent recurrence and metastasis after surgical procedures, thrombosis and thromboembolism is discussed, as is the possible link, through the substance P (SP)/NK-1R system, between cancer and depression. Our main aim is to review the multiple antitumor actions exerted by aprepitant, and the use of this drug is suggested in cancer patients. Altogether, the data support the reprofiling of aprepitant for a new therapeutic use as an antitumor agent.

Multifaceted Roles of DNA Methylation in Neoplastic Transformation, from Tumor Suppressors to EMT and Metastasis

Among the major mechanisms involved in tumorigenesis, DNA methylation is an important epigenetic modification impacting both genomic stability and gene expression. Methylation of promoter-proximal CpG islands (CGIs) and transcriptional silencing of tumor suppressors represent the best characterized epigenetic changes in neoplastic cells. The global cancer-associated effects of DNA hypomethylation influence chromatin architecture and reactivation of repetitive elements. Moreover, recent analyses of cancer cell methylomes highlight the role of the DNA hypomethylation of super-enhancer regions critically controlling the expression of key oncogenic players. We will first summarize some basic aspects of DNA methylation in tumorigenesis, along with the role of dysregulated DNA methyltransferases and TET (Ten-Eleven Translocation)-family methylcytosine dioxygenases. We will then examine the potential contribution of epimutations to causality and heritability of cancer. By reviewing some representative genes subjected to hypermethylation-mediated silencing, we will survey their oncosuppressor functions and roles as biomarkers in various types of cancer. Epithelial-to-mesenchymal transition (EMT) and the gain of stem-like properties are critically involved in cancer cell dissemination, metastasis, and therapeutic resistance. However, the driver vs passenger roles of epigenetic changes, such as DNA methylation in EMT, are still poorly understood. Therefore, we will focus our attention on several aspects of DNA methylation in control of EMT and metastasis suppressors, including both protein-coding and noncoding genes.

The role of substance P/neurokinin 1 receptor in the pathogenesis of esophageal squamous cell carcinoma through constitutively active PI3K/Akt/NF-κB signal transduction pathways

One of the most prevalent malignancies is esophageal squamous cell carcinoma (ESCC), which is associated with high morbidity and mortality. Substance P (SP), as one of the peptides released from sensory nerves, causes the enhancement of cellular excitability through the activation of the neurokinin-1 (NK1) receptor in several human tumor cells. Aprepitant, a specific, potent, and long-acting NK1 receptor antagonist, is considered as a novel agent to inhibit proliferation and induce apoptosis in malignant cells. Since the antitumor mechanism of aprepitant in ESCC is not completely understood, we conducted this study and found that aprepitant induced growth inhibition of KYSE-30 cells and arrested cells in the G2/M phase of the cell cycle. Aprepitant also caused apoptotic cell death and inhibited activation of the PI3K/Akt axis and its downstream effectors, including NF-κB in KYSE-30 cells. Besides, quantitative real-time (qRT)-PCR analysis showed a significant down-regulation of NF-κB target genes in KYSE-30 cells, indicating a probable NF-κB-dependent mechanism involved in aprepitant cytotoxicity. Thus, the present study recommends that SP/NK1R system might, therefore, be considered as an emerging and promising therapeutic strategy against ESCC.

Promoter methylation of galanin receptors as epigenetic biomarkers for head and neck squamous cell carcinomas

INTRODUCTION

While remarkable progress has been made in standard treatments for head and neck squamous cell carcinomas (HNSCCs), the long-term survival remains at an unsatisfactory 40-50%. To improve the survival rate, biomarkers for optimal treatment selection and prognostic prediction, as well as novel, low-toxicity treatment strategies, are required. Galanin receptor (GALR) 1 and GALR2 are well-studied tumor suppressors in HNSCCs. Compared with other clinicopathological factors, the epigenetic variants of GALRs have been found to be the most powerful markers to predict the prognosis of HNSCC patients. Areas covered: This review outlines the functions and signaling pathways of GALRs and explains the potential of GALR promoter methylation as a biomarker for HNSCC prognosis. We also summarize recent developments in promoter methylation studies in HNSCC and indicate future directions for GALR promoter methylation studies. Expert commentary: GALR studies have highlighted two major aspects with implications in HNSCC - that G-protein coupled receptors (GPCRs) act as tumor suppressor genes and that GALR promoter methylation is significantly related to the carcinogenesis of HNSCC. The findings of GALR studies can be applied to studies on other GPCRs and further in-depth DNA methylation studies. Deeper insights into GPCR epigenetics are expected to markedly improve HNSCC treatment.

Association of TET3 epigenetic inactivation with head and neck cancer

The aim of this study was to clarify the epigenetic regulation of ten eleven translocation protein (TET) family genes, which can provide insights into the mechanisms of tumorigenesis and the risk of disease recurrence in head and neck squamous cell carcinoma (HNSCC). We generated methylation profiles of TET1, TET2 and TET3 genes in tumor samples obtained from 233 patients with HNSCC; these included 57 hypopharynx, 44 larynx, 69 oral cavity, and 63 oropharynx tumor samples. The mRNA expression and promoter DNA methylation of TET family genes were examined via quantitative RT-PCR and methylation-specific PCR, respectively. Promoter methylation was compared with various clinical characteristics and the TET methylation index (TE-MI). The TE-MI, representing the number of methylation events in TET family genes, was positively correlated with alcohol consumption (P = 0.004), high-risk human papilloma virus (HPV) status (P = 0.004) and disease recurrence (P = 0.002). The simultaneous methylation analysis of TET family genes was correlated with reduced disease-free survival in unfavorable event groups (log-rank test, P = 0.026). In the multivariate Cox proportional hazards analysis, TET3 methylation in T1 and T2 tumor stages, oropharyngeal cancer, and oral cancer patients exhibited high association with poor survival (hazard ratio: 2.64, P = 0.014; 3.55, P = 0.048; 2.63, P = 0.028, respectively). A joint analysis of the tumor suppressor gene methylation index showed a significant trend toward a higher TE-MI. The methylation status of TET3 was independently associated with aggressive tumor behavior and a global effect on DNA methylation status in HNSCC.

The neuropeptide genes SST, TAC1, HCRT, NPY, and GAL are powerful epigenetic biomarkers in head and neck cancer: a site-specific analysis

Background

Staging and pathological grading systems are convenient but imperfect predictors of recurrence in head and neck squamous cell carcinoma (HNSCC). Identifying biomarkers for HNSCC that will progress and cause death is a critical research area, particularly if the biomarker can be linked to selection of patients. Therefore, to identify potential alternative prognostic markers, we investigated the methylation status of five neuropeptide gene promoters. The promoter methylation status was determined by quantitative methylation-specific PCR in 230 cases of HNSCC; 58 hypopharynx, 45 larynx, 56 oropharynx, and 71 oral cavity tumor samples were studied.

Results

The somatostatin (SST), tachykinin precursor 1 (TAC1), hypocretin neuropeptide precursor (HCRT), neuropeptide Y (NPY), and galanin (GAL) promoters were methylated in 84.3, 63.5, 32.6, 28.3, and 20.0%, respectively, of the samples. The mean number of methylated genes per sample was 2.29 (range, 0–5). Disease-free survival was lower in patients with 3–5 methylated genes than in those with 0–2 methylated genes (log-rank test, P = 0.007). In multivariate Cox proportional hazards analysis, TAC1 and GAL promoter methylation independently predicted recurrence (odds ratios 1.620, 95% confidence interval [CI] 1.018–2.578, P = 0.042, and odds ratios 1.692, 95% CI 1.063–2.694, P = 0.027, respectively). In patients with oral cancer, TAC1 methylation showed the best correlation with poor survival (odds ratio 4.427, 95% CI 1.634–12.00, P = 0.003). Similar findings were observed for HCRT and GAL in patients with laryngeal cancer and oropharyngeal cancer, respectively.

Conclusion

In this study, we demonstrated the methylation status of the neuropeptide-encoding genes SST, TAC1, HCRT, NPY, and GAL and its relationship with recurrence and survival in HNSCC. These methylation changes may serve as potential molecular markers for defining the risk and prognosis of HNSCC.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0485-0) contains supplementary material, which is available to authorized users.

Prognostic value of aberrant promoter hypermethylation of tumor-related genes in early-stage head and neck cancer

Staging and pathological grading are useful, but imperfect predictors of recurrence in head and neck squamous cell carcinoma (HNSCC). Accordingly, molecular biomarkers that predict the risk of recurrence are necessary to improve clinical outcomes. The methylation statuses of the promoters of 11 tumor-related genes (p16, RASSF1A, E-cadherin, H-cadherin, MGMT, DAPK, DCC, COL1A2, TAC1, SST, and GALR1) were analyzed in 133 HNSCC cases using quantitative methylation-specific PCR. We detected frequent methylation of p16 (44%), RASSF1A (18%), E-cadherin (53%), H-cadherin (35%), MGMT (35%), DAPK (53%), DCC (42%), COL1A2 (44%), TAC1 (61%), SST (64%), and GALR1 (44%) in HNSCC. Disease-free survival was lower in patients with 6–11 methylated genes than in those with 0–5 methylated genes (log-rank test, P = 0.001). In a multivariate Cox proportional hazards analysis, the methylation of E-cadherin, COL1A2, TAC1, and GALR1 was associated with poor survival, with hazard ratios of 4.474 (95% CI, 1.241–16.124). In a joint analysis of these four genes, patients with 2–4 methylated genes had a significantly lower survival rate than those with 0–1 methylated genes in early-stage HNSCC. Importantly, the methylation of some genes was closely related to poor prognosis in early-stage HNSCC, providing strong evidence that these hypermethylated genes are valuable biomarkers for prognostic evaluation.

Analysis of Site-Specific Methylation of Tumor-Related Genes in Head and Neck Cancer: Potential Utility as Biomarkers for Prognosis

Clarifying the epigenetic regulation of tumor-related genes (TRGs) can provide insights into the mechanisms of tumorigenesis and the risk for disease recurrence in HPV-negative head and neck cancers, originating in the hypopharynx, larynx, and oral cavity. We analyzed the methylation status of the promoters of 30 TRGs in 178 HPV-negative head and neck cancer patients using a quantitative methylation-specific PCR. Promoter methylation was correlated with various clinical characteristics and patient survival. The mean number of methylated TRGs was 14.2 (range, 2-25). In the multivariate Cox proportional hazards analysis, the methylation of COL1A2 and VEGFR1 was associated with poor survival for hypopharyngeal cancer, with hazard ratios: 3.19; p = 0.009 and 3.07; p = 0.014, respectively. The methylation of p16 and COL1A2 were independent prognostic factors for poor survival in laryngeal cancer (hazard ratio: 4.55; p = 0.013 and 3.12; p = 0.035, respectively). In patients with oral cancer, the methylation of TAC1 and SSTR1 best correlated with poor survival (hazard ratio: 4.29; p = 0.005 and 5.38; p = 0.029, respectively). Our findings suggest that methylation status of TRGs could serve as important site-specific biomarkers for prediction of clinical outcomes in patients with HPV-negative head and neck cancer.

Genes encoding neuropeptide receptors are epigenetic markers in patients with head and neck cancer: a site-specific analysis

Staging and pathological grading systems are useful but imperfect predictors of recurrence in head and neck squamous cell carcinoma (HNSCC). To identify potential prognostic markers, we examined the methylation status of eight neuropeptide receptor gene promoters in 231 head and neck squamous cell carcinomas. The NPFFR1, NPFFR2, HCRTR1, HCRTR2, NPY1R, NPY2R, NPY4R, and NPY5R promoters were methylated in 80.5%, 79.2%, 67.1%, 73.2%, 35.1%, 36.4%, 38.5%, and 35.9% of the samples, respectively. In a multivariate Cox proportional hazards analysis, the odds ratio for recurrence was 2.044 (95% confidence interval [CI], 1.323–3.156; P = 0.001) when the NPY2R promoter was methylated. In patients without lymph node metastasis (n = 100), methylation of NPY2R (compared with methylation of the other seven genes) best correlated with poor disease-free survival (DFS) (odds ratio, 2.492; 95% CI, 1.190–5.215; P = 0.015). In patients with oral cancer (n = 69), methylated NPY1R and NPY2R were independent prognostic factors for poor DFS, both individually and, even more so, in combination (odds ratio, 3.90; 95% CI, 1.523–9.991; P = 0.005). Similar findings were observed for NPY2R and NPY4R in patients with oropharyngeal cancer (n = 162) (odds ratio, 5.663; 95% CI, 1.507–21.28; P = 0.010).

Regulation of DNA methylation on EEF1D and RPL8 expression in cattle

Dynamic changes to the epigenome play a critical role in a variety of biology processes and complex traits. Many important candidate genes have been identified through our previous genome wide association study (GWAS) on milk production traits in dairy cattle. However, the underlying mechanism of candidate genes have not yet been clearly understood. In this study, we analyzed the methylation variation of the candidate genes, EEF1D and RPL8, which were identified to be strongly associated with milk production traits in dairy cattle in our previous studies, and its effect on protein and mRNA expression. We compared DNA methylation profiles and gene expression levels of EEF1D and RPL8 in five different tissues (heart, liver, mammary gland, ovary and muscle) of three cows. Both genes showed the highest expression level in mammary gland. For RPL8, there was no difference in the DNA methylation pattern in the five tissues, suggesting no effect of DNA methylation on gene expression. For EEF1D, the DNA methylation levels of its first CpG island differed in the five tissues and were negatively correlated with the gene expression levels. To further investigate the function of DNA methylation on the expression of EEF1D, we collected blood samples of three cows at early stage of lactation and in dry period and analyzed its expression and the methylation status of the first CpG island in blood. As a result, the mRNA expression of EEF1D in the dry period was higher than that at the early stage of lactation, while the DNA methylation level in the dry period was lower than that at the early stage of lactation. Our result suggests that the DNA methylation of EEF1D plays an important role in the spatial and temporal regulation of its expression and possibly have an effect on the milk production traits.

Epigenetic control of cancer by neuropeptides

Neuropeptides act as neurohormones, neurotransmitters and/or neuromodulators. Neuropeptides maintain physiological homeostasis and are paramount in molecular mechanisms of disease progression and regulation, including in cancer. Neuropeptides, by their definition, originate and are secreted from the neuronal cells, they are able to signal to neighboring cells or are released into the blood flow, if they act as neurohormones. The majority of neuropeptides exert their functions through G protein-coupled receptors, with certain exceptions. Although previous studies indicate that neuropeptides function in supporting proliferation of malignant cells in many types of solid tumor, the antitumorigenic action of the neuropeptides and their receptors, for example, in gastric cancers and chondrosarcoma, were also reported. It is known that epigenetically modified chromatin regulates molecular mechanisms involved in gene expression and malignant progression. The epigenetic modifications are genetically heritable, although they do not cause changes in DNA sequence. DNA methylation, histone modifications and miRNA expression are subject to those modifications. While there is substantial data on epigenetic regulation of neuropeptides, the epigenetic control of cancer by neuropeptides is considered to be uncharted territory. The aim of the current review is to describe the involvement of neuropeptides in the epigenetic machinery of cancer based on data obtained from our laboratory and from other authors.

Truncated neurokinin-1 receptor is an ubiquitous antitumor target in hepatoblastoma, and its expression is independent of tumor biology and stage

The substance P (SP; also known as TAC1)/neurokinin-1 receptor (NK1R; also known as TACR1) complex is a critical part in the development of cancer. Therefore, NK1R antagonists, such as the clinical drug aprepitant, are currently under investigation as future anticancer agents. In a previous study, NK1R (TACR1) was identified as a potent anticancer target in hepatoblastoma (HB). However, little is known regarding the exact distribution of this target among HB subsets and whether it correlates with clinical features and prognosis. In the present study, mRNA was isolated from 47 children with HB, and reverse transcription-quantitative polymerase chain reaction was performed on the samples to analyze the expression of full-length-TACR1 (fl-TACR1) and truncated-TACR1 (tr-TACR1). These data were correlated with data obtained from 9 tumor-free controls, as well as with the presence of metastasis, PRETEXT, vascular invasion, histology, age of diagnosis, multifocality, CTNNB1 mutation, gender and overall survival. Additionally, the present study investigated a recently described 16-gene signature characterizing HB known to correlate with prognosis. Compared with tumor-free liver tissue, tumorous tissue expressed TACR1 significantly higher for the truncated version (P=0.0301), and by trend also for the full-length version. Accordingly, the expression of fl-TACR1 correlated with the expression of the truncated version (P=0.0074). Furthermore, a low expression of fl-TACR1 correlated with characteristics of the 16-gene signature known to predict prognosis (P=0.0222). However, there was no correlation between tr-TACR1 and the tumor characteristics investigated, including outcome, although a clear trend was observed for some tumor characteristics. The current results reinforced the previously described findings that in HB, tr-TACR1 is overexpressed compared with tumor-free liver tissue. Furthermore, to the best of our knowledge, the present study demonstrated for the first time that tr-TACR1 is expressed ubiquitously among the different subsets of HB. Therefore, NK1R may serve as a potent anticancer target in a large variety of patients with HB, independent of tumor biology and clinical stage.

Epigenetic inactivation of galanin and GALR1/2 is associated with early recurrence in head and neck cancer

The aim of this study was to investigate the prognostic value of galanin (GAL) and galanin receptor (GALR) promoter hypermethylation in patients with head and neck squamous cell carcinoma (HNSCC). The methylation status of three genes-GAL, GALR1, and GALR2 was examined in HNSCC patient tumors using quantitative methylation-specific PCR (Q-MSP). To determine the prognostic value of GAL, GALR1 and GALR2 methylation status, their associations with various clinical characteristics and patient survival were assessed in HNSCC patient tumors (n = 142). Aberrant methylation of at least one gene was observed in 84 of the 142 (59.2 %) primary tumors analyzed. The methylation index, defined as the ratio between the number of methylated genes and the number of genes examined, was positively correlated with larger tumor size (P = 0.034) and disease recurrence (P < 0.001). In the multivariate logistic-regression analysis, methylation of both GAL and GALR1 exhibited the highest association with poor survival (hazard ratio, 6.83, P = 0.002). Moreover, among patients without lymph node metastasis, a multivariate analysis showed a significant trend for poor survival as the number of hypermethylated genes increased (log-rank test, P = 0.003). CpG hypermethylation is a likely mechanism of GAL and GALR1/2 gene inactivation, indicating that GAL and its receptors play a role in HNSCC tumorigenesis. As such, GAL and GALR1/2 methylation status may serve as an important biomarker for clinical outcome.

G-Protein-Coupled Receptors: Next Generation Therapeutic Targets in Head and Neck Cancer?

Therapeutic outcome in head and neck squamous cell carcinoma (HNSCC) is poor in most advanced cases. To improve therapeutic efficiency, novel therapeutic targets and prognostic factors must be discovered. Our studies have identified several G protein-coupled receptors (GPCRs) as promising candidates. Significant epigenetic silencing of GPCR expression occurs in HNSCC compared with normal tissue, and is significantly correlated with clinical behavior. Together with the finding that GPCR activity can suppress tumor cell growth, this indicates that GPCR expression has potential utility as a prognostic factor. In this review, we discuss the roles that galanin receptor type 1 (GALR1) and type 2 (GALR2), tachykinin receptor type 1 (TACR1), and somatostatin receptor type 1 (SST1) play in HNSCC. GALR1 inhibits proliferation of HNSCC cells though ERK1/2-mediated effects on cell cycle control proteins such as p27, p57, and cyclin D1, whereas GALR2 inhibits cell proliferation and induces apoptosis in HNSCC cells. Hypermethylation of GALR1, GALR2, TACR1, and SST1 is associated with significantly reduced disease-free survival and a higher recurrence rate. Although their overall activities varies, each of these GPCRs has value as both a prognostic factor and a therapeutic target. These data indicate that further study of GPCRs is a promising strategy that will enrich pharmacogenomics and prognostic research in HNSCC.

Aberrant methylation inactivates somatostatin and somatostatin receptor type 1 in head and neck squamous cell carcinoma

PURPOSE

The aim of this study was to define somatostatin (SST) and somatostatin receptor type 1 (SSTR1) methylation profiles for head and neck squamous cell carcinoma (HNSCC) tumors at diagnosis and follow up and to evaluate their prognostic significance and value as a biomarker.

METHODS

Gene expression was measured by quantitative RT-PCR. Promoter methylation status was determined by quantitative methylation-specific PCR (Q-MSP) in HNSCC.

RESULTS

Methylation was associated with transcription inhibition. SST methylation in 81% of HNSCC tumor specimens significantly correlated with tumor size (P = 0.043), stage (P = 0.008), galanin receptor type 2 (GALR2) methylation (P = 0.041), and tachykinin-1 (TAC1) (P = 0.040). SSTR1 hypermethylation in 64% of cases was correlated with tumor size (P = 0.037), stage (P = 0.037), SST methylation (P < 0.001), and expression of galanin (P = 0.03), GALR2 (P = 0.014), TAC1 (P = 0.023), and tachykinin receptor type 1 (TACR1) (P = 0.003). SST and SSTR1 promoter hypermethylation showed highly discriminating receiver operator characteristic curve profiles, which clearly distinguished HNSCC from adjacent normal mucosal tissues. Concurrent hypermethylation of galanin and SSTR1 promoters correlated with reduced disease-free survival (log-rank test, P = 0.0001). Among patients with oral cavity and oropharynx cancer, methylation of both SST and SSTR1 promoters correlated with reduced disease-free survival (log-rank test, P = 0.028). In multivariate logistic-regression analysis, concomitant methylation of galanin and SSTR1 was associated with an odds ratio for recurrence of 12.53 (95% CI, 2.62 to 59.8; P = 0.002).

CONCLUSIONS

CpG hypermethylation is a likely mechanism of SST and SSTR1 gene inactivation, supporting the hypothesis that SST and SSTR1 play a role in the tumorigenesis of HNSCC and that this hypermethylation may serve as an important biomarker.

Predictive value of epigenetic alterations in head and neck squamous cell carcinoma

Head and neck cancer collectively describes malignant tumors originating from the mucosal surface of the upper aerodigestive tract. These tumors pose a great threat to public health because of their high incidence and mortality. Traditional risk factors are tobacco and alcohol abuse. More recently, infection by high-risk types of human papilloma virus (HPV) has been identified as an additional risk factor, especially for oropharyngeal squamous cell carcinoma (OPSCC). Moreover, HPV-positive OPSCC is considered a distinct tumor entity with an improved clinical outcome compared to HPV-negative OPSCC. Epigenetic alterations act as key events in the pathogenesis of cancer and are of special interest for basic and translational oncology because of their reversible nature. This review provides a comprehensive summary of alterations of the epigenome in head and neck squamous cell carcinoma (HNSCC) with a focus on the methylome (hypomethylation and hypermethylation) and its predictive value in the evaluation of pathologic states and clinical outcome, or monitoring response rates to certain therapies.

Differential gene expression of the key signalling pathway in para-carcinoma, carcinoma and relapse human pancreatic cancer

Pancreatic cancer (PC) has a high rate of mortality and a poorly understood mechanism of progression. Investigation of the molecular mechanism of PC and exploration of the specific markers for early diagnosis and specific targets of therapy are key points to prevent and treat PC effectively and to improve their prognosis. In our study, expression profiles experiment of para-carcinoma, carcinoma and relapse human PC was performed using Agilent human whole genomic oligonucleotide microarrays with 45 000 probes. Differentially expressed genes related with PC were screened and analysed further by Gene Ontology term analysis and Kyoto encyclopaedia of genes and genomes pathway analysis. Our results showed that there were 3853 differentially expressed genes associated with pancreatic carcinogenesis and relapse. In addition, our study found that PC was related to the Jak-STAT signalling pathway, PPAR signalling pathway and Calcium signalling pathway, indicating their potential roles in pancreatic carcinogenesis and progress.

Galanin has tumor suppressor activity and is frequently inactivated by aberrant promoter methylation in head and neck cancer

PURPOSE

There is accumulating evidence that galanin receptors (GALRs) may be tumor suppressors in head and neck squamous cell carcinoma (HNSCC). Promoter methylation status and gene expression were assessed in a large panel of primary tumors, based on the hypothesis that CpG hypermethylation might silence the galanin gene.

EXPERIMENTAL DESIGN

Galanin expression was examined using reverse transcription-polymerase chain reaction (PCR). The methylation status of the galanin promoter was studied using bisulfate sequencing and methylation-specific PCR. UM-SCC-54 was stably transfected to express galanin.

RESULTS

Galanin expression was absent in 3/12 (25.0%) UM-SCC cell lines, whereas three nonmalignant cell lines had stable expression. Galanin methylation was found in 24/100 (24.0%) cases. HNSCC tumor specimens was significantly correlated with the GALR1 methylation status (P = 1.88E-06). The presence of galanin promoter hypermethylation was statistically correlated with a decrease in disease-free survival (log-rank test, P = 6.02E-05). A multivariate logistic regression analysis showed that methylation of galanin and methylation of the gene pair galanin and GALR1 had an odds ratio for recurrence of 8.95 [95% confidence interval (CI), 2.29-35.03] and 23.84 (95% CI, 2.74-207.17), respectively. UM-SCC-54 cells that are GALR1-proficient but have hypermethylated galanin exhibited suppressed cell proliferation following exogenous expression of galanin.

CONCLUSIONS

Association of frequent promoter hypermethylation and gene silencing with poor survival, combined with growth suppression of HNSCC cells after forced gene expression, supports the hypothesis that galanin acts as a tumor suppressor. These data suggest that galanin and GALR1 are potential therapeutic targets and prognostic factors.