Epigenetic Modifications and Head and Neck Cancer: Implications for Tumor Progression and Resistance to Therapy

Early-Phase Interventional Trials in Oral Cancer Prevention

Simple Summary

Oral cancer is a devastating disease with increasing incidence worldwide. Oral epithelial dysplasia (OED) is a potentially malignant disorder and patients with OED are at increased risk of developing oral cancer. Current strategies for management of OED include surgery or close observation and both fail to address the underlying pathogenesis of the disease. There is an urgent need for evidence-based medical treatments for OED to prevent oral cancer development in this cohort. Chemoprevention trials to date have not delivered therapeutic agents for routine clinical practice. Historically, there has been significant heterogeneity in the design of oral cancer chemoprevention trials, with most failing to selectively recruit patients with biopsy-proven OED, which limits the usefulness of the findings in the OED population. The present paper aims to review the current evidence and the methodology of early-phase trials in oral cancer chemoprevention. Novel strategies in oral cancer chemoprevention will also be discussed.

Abstract

The increasing breadth of molecular targets, promise of immune-targeted therapies and repurposed agents have heightened interest in cancer prevention. While, to date, testing of oral cancer chemoprevention strategies has failed to deliver therapeutic agents for routine clinical practice, there remains an urgent need for further clinical research to overcome this hurdle. Patients at the greatest risk of disease stand to benefit the most from inclusion in clinical trials; therefore, there is a need to carefully define this population using validated clinical and molecular markers. Safety, tolerability and the efficacy of interventions is assessed through carefully selected endpoints. These endpoints may include pharmacodynamic, clinical, histological and on-target molecular modifications as an individual or as a composite endpoint. Early-phase trials provide an area of opportunity to explore novel and repurposed agents in the setting of oral cancer chemoprevention, eventually leading to phase III trials with clinical endpoints such as transformation and clinical outcome; these studies are large, lengthy and expensive and should be reserved for the most promising of agents. This paper will explore current evidence in oral cancer chemoprevention, drug repurposing, selection of appropriate endpoints for early-phase trials and novel therapeutic angles in oral cancer chemoprevention.

An aberrant DNA methylation signature for predicting the prognosis of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a common malignancy worldwide with a poor prognosis. DNA methylation is an epigenetic modification that plays a critical role in the etiology and pathogenesis of HNSCC. The current study aimed to develop a predictive methylation signature based on bioinformatics analysis to improve the prognosis and optimize therapeutic outcome in HNSCC. Clinical information and methylation sequencing data of patients with HNSCC were downloaded from The Cancer Genome Atlas database. The R package was used to identify differentially methylated genes (DMGs) between HNSCC and adjacent normal tissues. We identified 22 DMGs associated with 246 differentially methylated sites. Patients with HNSCC were classified into training and test groups. Cox regression analysis was used to build a risk score formula based on the five methylation sites (cg26428455, cg13754259, cg17421709, cg19229344, and cg11668749) in the training group. The Kaplan–Meier survival curves showed that the overall survival (OS) rates were significantly different between the high‐ and low‐risk groups sorted by the signature in the training group (median: 1.38 vs. 1.57 years, log‐rank test, p < 0.001). The predictive power was then validated in the test group (median: 1.34 vs. 1.75 years, log‐rank test, p < 0.001). The area under the receiver operating characteristic curve (area under the curve) based on the signature for predicting the 5‐year survival rates, was 0.7 in the training and 0.73 in test groups, respectively. The results of multivariate Cox regression analysis showed that the riskscore (RS) signature based on the five methylation sites was an independent prognostic tool for OS prediction in patients. In addition, a predictive nomogram model that incorporated the RS signature and patient clinical information was developed. The innovative methylation signature‐based model developed in our study represents a robust prognostic tool for guiding clinical therapy and predicting the OS in patients with HNSCC.

Nanomaterials for the Diagnosis and Treatment of Head and Neck Cancers: A Review

Head and neck cancer (HNC) is a category of cancers that typically arise from the nose-, mouth-, and throat-lining squamous cells. The later stage of HNC diagnosis significantly affects the patient's survival rate. This makes it mandatory to diagnose this cancer with a suitable biomarker and imaging techniques at the earlier stages of growth. There are limitations to traditional technologies for early detection of HNC. Furthermore, the use of nanocarriers for delivering chemo-, radio-, and phototherapeutic drugs represents a promising approach for improving the outcome of HNC treatments. Several studies with nanostructures focus on the development of a targeted and sustained release of anticancer molecules with reduced side effects. Besides, nanovehicles could allow co-delivering of anticancer drugs for synergistic activity to counteract chemo- or radioresistance. Additionally, a new generation of smart nanomaterials with stimuli-responsive properties have been developed to distinguish between unique tumor conditions and healthy tissue. In this light, the present article reviews the mechanisms used by different nanostructures (metallic and metal oxide nanoparticles, polymeric nanoparticles, quantum dots, liposomes, nanomicelles, etc.) to improve cancer diagnosis and treatment, provides an up-to-date picture of the state of the art in this field, and highlights the major challenges for future improvements.

Salivary DNA Methylation as an Epigenetic Biomarker for Head and Neck Cancer. Part II: A Cancer Risk Meta-Analysis

Aberrant methylation of tumor suppressor genes has been reported as an important epigenetic silencer in head and neck cancer (HNC) pathogenesis. Here, we performed a comprehensive meta-analysis to evaluate the overall and specific impact of salivary gene promoter methylation on HNC risk. The methodological quality was assessed using the Newcastle–Ottawa scale (NOS). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the association and Egger’s and Begg’s tests were applied to detect publication bias. The frequency of salivary DNA promoter methylation was significantly higher in HNC patients than in healthy controls (OR: 8.34 (95% CI = 6.10–11.39; p < 0.01). The pooled ORs showed a significant association between specific tumor-related genes and HNC risk: p16 (3.75; 95% CI = 2.51–5.60), MGMT (5.72; 95% CI = 3.00–10.91), DAPK (5.34; 95% CI = 2.18–13.10), TIMP3 (3.42; 95% CI = 1.99–5.88), and RASSF1A (7.69; 95% CI = 3.88–15.23). Overall, our meta-analysis provides precise evidence on the association between salivary DNA promoter hypermethylation and HNC risk. Thus, detection of promoter DNA methylation in saliva is a potential biomarker for predicting HNC risk.

Epigenetic modulation of the tumor microenvironment in head and neck cancer: Challenges and opportunities

Head and neck cancer is globally challenging due to the resistance to therapy and aggressive behavior leading to high rates of mortality. Recent findings show that the tumor microenvironment plays a role in the maintenance and progression of many solid tumors, including head and neck cancer. The mechanisms involved in the modulation and regulation of the tumor microenvironment remain poorly understood. Increasing evidence suggests that epigenetic events can modulate the crosstalk between neoplastic and non-neoplastic cells during tumor progression. In this review, we explore the current understanding of the involvement of epigenetic events in the modulation of the tumor microenvironment and its impact on head and neck cancer behavior. We also explore the latest therapeutic strategies that use epigenetic-modulating drugs to manage tumor growth and progression.

Kinase Inhibitors of DNA-PK, ATM and ATR in Combination with Ionizing Radiation Can Increase Tumor Cell Death in HNSCC Cells While Sparing Normal Tissue Cells

(1) Kinase inhibitors (KI) targeting components of the DNA damage repair pathway are a promising new type of drug. Combining them with ionizing radiation therapy (IR), which is commonly used for treatment of head and neck tumors, could improve tumor control, but could also increase negative side effects on surrounding normal tissue. (2) The effect of KI of the DDR (ATMi: AZD0156; ATRi: VE-822, dual DNA-PKi/mTORi: CC-115) in combination with IR on HPV-positive and HPV-negative HNSCC and healthy skin cells was analyzed. Cell death and cell cycle arrest were determined using flow cytometry. Additionally, clonogenic survival and migration were analyzed. (3) Studied HNSCC cell lines reacted differently to DDRi. An increase in cell death for all of the malignant cells could be observed when combining IR and KI. Healthy fibroblasts were not affected by simultaneous treatment. Migration was partially impaired. Influence on the cell cycle varied between the cell lines and inhibitors; (4) In conclusion, a combination of DDRi with IR could be feasible for patients with HNSCC. Side effects on healthy cells are expected to be limited to normal radiation-induced response. Formation of metastases could be decreased because cell migration is impaired partially. The treatment outcome for HPV-negative tumors tends to be improved by combined treatment.

Salivary DNA Methylation as an Epigenetic Biomarker for Head and Neck Cancer. Part I: A Diagnostic Accuracy Meta-Analysis

DNA hypermethylation is an important epigenetic mechanism for gene expression inactivation in head and neck cancer (HNC). Saliva has emerged as a novel liquid biopsy representing a potential source of biomarkers. We performed a comprehensive meta-analysis to evaluate the overall diagnostic accuracy of salivary DNA methylation for detecting HNC. PubMed EMBASE, Web of Science, LILACS, and the Cochrane Library were searched. Study quality was assessed by the Quality Assessment for Studies of Diagnostic Accuracy-2, and sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (dOR), and their corresponding 95% confidence intervals (CIs) were calculated using a bivariate random-effect meta-analysis model. Meta-regression and subgroup analyses were performed to assess heterogeneity. Eighty-four study units from 18 articles with 8368 subjects were included. The pooled sensitivity and specificity of salivary DNA methylation were 0.39 and 0.87, respectively, while PLR and NLR were 3.68 and 0.63, respectively. The overall area under the curve (AUC) was 0.81 and the dOR was 8.34. The combination of methylated genes showed higher diagnostic accuracy (AUC, 0.92 and dOR, 36.97) than individual gene analysis (AUC, 0.77 and dOR, 6.02). These findings provide evidence regarding the potential clinical application of salivary DNA methylation for HNC diagnosis.

Differential molecular response of larynx cancer cell lines to combined VPA/CDDP treatment

Successful treatment of advanced larynx squamous cell carcinoma (LSCC) remains a challenge, mainly due to limited response to chemotherapy and the phenomenon of the drug resistance. Therefore, new chemotherapeutic solutions are needed. The aim of this study was to explore benefit of combined cisplatin (CDDP) and valproic acid (VPA) therapy in patients' derived LSCC cell lines. Cell viability assay was used to establish cellular response to the drug by isobolography followed by RNA sequencing (RNAseq) analysis. Danio rerio were used for in vivo studies. Depending on the cell line, we found that the combinations of drugs resulted in synergistic or antagonistic pharmacological interaction, which was accompanied by significant changes in genes expression profiles. The presented therapeutic scheme efficiently blocked tumor growth in an in vivo model, corresponding to the in vitro performed studies. Interestingly the RK5 cell line, upon the combined treatment acquired a molecular profile typically associated with epithelial to mesenchymal transition (EMT). Hence, our studies demonstrates that patient-specific personalized therapy of larynx cancer should be considered and the combination of cisplatin and valproic acid should be explored as a potential therapeutic strategy in the treatment of larynx cancer.

Assessment of MicroRNA (miR)-365 Effects on Oral Squamous Carcinoma Cell Line Phenotypes

miR-365 is a microRNA that regulates transcription and has been demonstrated to promote oncogenesis and metastasis in some cancers while suppressing these effects in others. Virtually no information is known about the presence or function of miR-365 in oral cancers. Based upon this information, the primary goal of this project was to evaluate the expression of miR-365 in existing oral cancer cell lines. Five commercially available oral cancer cell lines (SCC4, SCC9, SCC15, SCC25, and CAL27) were obtained and cultured. RNA was then screened by PCR using primers specific for miR-365, as well as matrix metalloproteinase (MMP-2) and a downstream cancer stem cell regulator (NKX2.1), and structural and metabolic standards (beta actin, GAPDH). miR-365 was detected among these oral cancers, and some cells also expressed NKX2.1 and MMP-2, which correlated with miR-365 levels. The relative expression of miR-365, NKX2.1, and MMP-2 RNA was higher than expected. Transfection of miR-365 resulted in a significant increase in proliferation, which was not observed in the negative controls. These data appear to confirm miR-365 expression in oral cancers, which may also be correlated with MMP-2 and NKX2.1 expression. Moreover, the fastest growing oral cancers with the highest viability produced the most miR-365. In addition, miR-365 transfected into cells significantly increased growth, even in normal cells. More research is needed to elucidate the pathways responsible for these observations.

Current understanding of epigenetics mechanism as a novel target in reducing cancer stem cells resistance

At present, after extensive studies in the field of cancer, cancer stem cells (CSCs) have been proposed as a major factor in tumor initiation, progression, metastasis, and recurrence. CSCs are a subpopulation of bulk tumors, with stem cell-like properties and tumorigenic capabilities, having the abilities of self-renewal and differentiation, thereby being able to generate heterogeneous lineages of cancer cells and lead to resistance toward anti-tumor treatments. Highly resistant to conventional chemo- and radiotherapy, CSCs have heterogeneity and can migrate to different organs and metastasize. Recent studies have demonstrated that the population of CSCs and the progression of cancer are increased by the deregulation of different epigenetic pathways having effects on gene expression patterns and key pathways connected with cell proliferation and survival. Further, epigenetic modifications (DNA methylation, histone modifications, and RNA methylations) have been revealed to be key drivers in the formation and maintenance of CSCs. Hence, identifying CSCs and targeting epigenetic pathways therein can offer new insights into the treatment of cancer. In the present review, recent studies are addressed in terms of the characteristics of CSCs, the resistance thereof, and the factors influencing the development thereof, with an emphasis on different types of epigenetic changes in genes and main signaling pathways involved therein. Finally, targeted therapy for CSCs by epigenetic drugs is referred to, which is a new approach in overcoming resistance and recurrence of cancer.

4sc-202 and Ink-128 cooperate to reverse the epithelial to mesenchymal transition in OSCC

Treatment of oral squamous cell carcinoma remains a challenge due to a high incidence of treatment resistance, which is followed by tumor recrudescence and metastasis to the lymph nodes. Thus, it is important to explore novel inhibitors of OSCC. Here, we aimed to identify drugs that may cooperate with histone deacetylase inhibitors to reverse the EMT, inhibit EMT and cell migration and invasion, and contribute to therapeutic efficacy. We found that treatment with 4sc-202 potently reversed the EMT and thereby inhibited cell migration and invasion in vitro, in part by inducing expression of the FoxO1 tumor-suppressor gene. Furthermore, 4sc-202 also synergized with Ink-128 to inhibit tumor migration and invasion in vitro. Mechanistically, 4sc-202 induced FoxO1 expression, whereas Ink-128 promoted nuclear translocation of FoxO1. Our findings indicated that FoxO1 might reverse the EMT by interacting with Twist1 in OSCC. In conclusion, we identified an effective combination therapy involving class I histone deacetylase and mammalian target of rapamycin complex 1/2 inhibition that effectively blocked the EMT of tumor cells by upregulating FoxO1 expression to inhibit Twist1 transcription. These data have implications for developing new targets for early diagnosis and treatment of OSCC.

Ubiquitin chromatin remodelling after DNA damage is associated with the expression of key cancer genes and pathways

Modification of the cancer-associated chromatin landscape in response to therapeutic DNA damage influences gene expression and contributes to cell fate. The central histone mark H2Bub1 results from addition of a single ubiquitin on lysine 120 of histone H2B and is an important regulator of gene expression. Following treatment with a platinum-based chemotherapeutic, there is a reduction in global levels of H2Bub1 accompanied by an increase in levels of the tumor suppressor p53. Although total H2Bub1 decreases following DNA damage, H2Bub1 is enriched downstream of transcription start sites of specific genes. Gene-specific H2Bub1 enrichment was observed at a defined group of genes that clustered into cancer-related pathways and correlated with increased gene expression. H2Bub1-enriched genes encompassed fifteen p53 target genes including PPM1D, BTG2, PLK2, MDM2, CDKN1A and BBC3, genes related to ERK/MAPK signalling, those participating in nucleotide excision repair including XPC, and genes involved in the immune response and platinum drug resistance including POLH. Enrichment of H2Bub1 at key cancer-related genes may function to regulate gene expression and influence the cellular response to therapeutic DNA damage.

Liquid biopsy in head and neck squamous cell carcinoma: circulating tumor cells, circulating tumor DNA, and exosomes

Introduction: Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers worldwide. Due to a lack of reliable markers, HNSCC patients are usually diagnosed at a late stage, which will lead to a worse outcome. Therefore, it is critical to improve the clinical management of cancer patients. Nowadays, the development of liquid biopsy enables a minimally invasive manner to extract molecular information from HNSCCs. Thus, this review aims to outline the clinical value of liquid biopsy in early detection, real-time monitoring, and prognostic evaluation of HNSCC. Areas covered: This comprehensive review focused on the characteristics as well as clinical applications of three liquid biopsy markers (CTCs, ctDNA, and exosomes) in HNSCC. What is more, it is promising to incorporate machine learning and 3D organoid models in the liquid biopsy of HNSCC. Expert opinion: Liquid biopsy provides a noninvasive technique to reflect the inter and intra-lesional heterogeneity through the detection of tumor cells or materials released from the primary and secondary tumors. Recently, some evolving technologies have the potential to combine with liquid biopsy to improve clinical management of HNSCC patients.

Current Trends and Future Prospects of Molecular Targeted Therapy in Head and Neck Squamous Cell Carcinoma

In recent years, advances in drug therapy for head and neck squamous cell carcinoma (HNSCC) have progressed rapidly. In addition to cytotoxic anti-cancer agents such as platinum-based drug (cisplatin and carboplatin) and taxane-based drugs (docetaxel and paclitaxel), epidermal growth factor receptor-tyrosine kinase inhibitors (cetuximab) and immune checkpoint inhibitors such as anti-programmed cell death-1 (PD-1) antibodies (nivolumab and pembrolizumab) have come to be used. The importance of anti-cancer drug therapy is increasing year by year. Therefore, we summarize clinical trials of molecular targeted therapy and biomarkers in HNSCC from previous studies. Here we show the current trends and future prospects of molecular targeted therapy in HNSCC.

Head and Neck Squamous Cell Carcinoma: Epigenetic Landscape

Head and neck squamous carcinoma (HNSCC) constitutes the sixth most prevalent cancer worldwide. The molecular pathogenesis of HNSCC includes disorders in cell cycle, intercellular signaling, proliferation, squamous cell differentiation and apoptosis. In addition to the genetic mutations, changes in HNSCC are also characterized by the accumulation of epigenetic alterations such as DNA methylation, histone modifications, non-coding RNA activity and RNA methylation. In fact, some of them may promote cancer formation and progression by controlling the gene expression machinery, hence, they could be used as biomarkers in the clinical surveillance of HNSCC or as targets for therapeutic strategies. In this review, we focus on the current knowledge regarding epigenetic modifications observed in HNSCC and its predictive value for cancer development.

Analysis of DNA methylation of E-cadherin and p16ink4a in oral lichen planus/oral lichenoid lesions

OBJECTIVES

Epigenetic phenomena are changes in gene expression not involving the DNA sequence. DNA methylation is a major occurrence underlying epigenetic changes in human cells. Although aberrant DNA methylation is well documented in malignant lesions, limited information has been shown on the involvement of DNA methylation in oral lichen planus and oral lichenoid lesions (OLP). The present study aimed to investigate DNA methylation of E-cadherin and p16 in OLP, and compare the findings with those in non-inflamed gingiva (Non), radicular cyst (RC), and oral squamous cell carcinoma (SCC).

MATERIALS AND METHODS

Paraffin-embedded surgical biopsy specimens were sliced, DNA was extracted, bisulfite treatment was applied, and methylation-specific polymerase chain reaction was performed. Immunohistochemistry was performed to observe the relative expression patterns of these genes.

RESULTS

E-cadherin was hypermethylated in OLP (p < 0.01), SCC (p < 0.01), and RC (p < 0.05), when compared with Non; DNA hypermethylation was confirmed in OLP and SCC when compared to Non and RC. Hypermethylation of p16^ink4a was observed only in SCC (p < 0.01).

CONCLUSION

DNA methylation levels of E-cadherin and p16^ink4a were significantly higher in OLP than in normal tissues, and may be associated with the pathogenesis and progression of the disease.

Anaerobic bacterial communities associated with oral carcinoma: Intratumoral, surface-biofilm and salivary microbiota

It was estimated that more than 700 bacterial species inhabit the oral cavity of healthy humans. Anaerobes comprise a significant fraction of the oral bacteriome and play an important role in the formation of multi-species biofilms attached to various anatomical sites. Bacterial biofilms are also associated with pathologic laesions of the oral cavity, including oral squamous cell carcinoma (OSCC), and distinct oral taxa could also be detected within the tumors, i.e. in deep biopsy samples. These observations suggested that certain oral bacteria or oral bacterial communities may play a causative role in oral carcinogenesis, in addition to the well characterized risk factors of oral cancer. Alternatively, it was also proposed that a subset of oral bacteria may have a growth advantage in the unique microenvironment of OSCC. Recently, a series of studies analysed the OSCC-associated bacterial communities using metataxonomic, metagenomic and metatranscriptomic approaches. This review outlines the major differences between the community structure of microbiota in tumor biopsy, surface-biofilm and salivary or oral wash samples collected from OSCC patients, compared to corresponding samples from control persons. A special emphasis is given to the anaerobic bacteria Fusobacterium nucleatum and Fusobacterium periodonticum that were characterised repeatedly as "OSCC-associated" in independent studies. Predicted microbial functions and relevant in vivo experimental models of oral carcinogenesis will also be summarized.

5-Hydroxymethylation highlights the heterogeneity in keratinization and cell junctions in head and neck cancers

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer worldwide, with human papillomavirus (HPV)-related HNSCC rising to concerning levels. Extensive clinical, genetic and epigenetic differences exist between HPV-associated HNSCC and HPV-negative HNSCC, which is often linked to tobacco use. However, 5-hydroxymethylation (5hmC), an oxidative derivative of DNA methylation and its heterogeneity among HNSCC subtypes, has not been studied.

RESULTS

We characterized genome-wide 5hmC profiles in HNSCC by HPV status and subtype in 18 HPV(+) and 18 HPV(-) well-characterized tumors. Results showed significant genome-wide hyper-5hmC in HPV(-) tumors, with both promoter and enhancer 5hmC able to distinguish meaningful tumor subgroups. We identified specific genes whose differential expression by HPV status is driven by differential hydroxymethylation. CDKN2A (p16), used as a key biomarker for HPV status, exhibited the most extensive hyper-5hmC in HPV(+) tumors, while HPV(-) tumors showed hyper-5hmC in CDH13, TIMP2, MMP2 and other cancer-related genes. Among the previously reported two HPV(+) subtypes, IMU (stronger immune response) and KRT (more keratinization), the IMU subtype revealed hyper-5hmC and up-regulation of genes in cell migration, and hypo-5hmC with down-regulation in keratinization and cell junctions. We experimentally validated our key prediction of higher secreted and intracellular protein levels of the invasion gene MMP2 in HPV(-) oral cavity cell lines.

CONCLUSION

Our results implicate 5hmC in driving differences in keratinization, cell junctions and other cancer-related processes among tumor subtypes. We conclude that 5hmC levels are critical for defining tumor characteristics and potentially used to define clinically meaningful cancer patient subgroups.

Analysis of chemotherapy effect on the second primary malignancy for head and neck cancer patients by a nomogram based on SEER database

Second primary malignancy (SPM) ranks the second leading cause of death in patients with head and neck cancer (HNC), while studies exploring the risk factors for SPM are limited. To clarify this, we investigated the relationship between the chemotherapy and SPM using the Surveillance, Epidemiology, and End Results (SEER) database. 11 345 patients initially diagnosed with HNC between 1998 and 2016 were selected from the SEER database. First, these patients were divided into two groups according to chemotherapy or not. With Fine and Gray model, the subdistribution hazard ratio (sHR) of chemotherapy was calculated based on Propensity Score Matching (PSM). Second, the 11 345 cases were randomized into a training set and a validation set. Based on the training set, the different cumulative incidence of SPMs between the patients with and without chemotherapy was estimated respectively in the high‐ and low‐risk group according to the scores derived from a nomogram. Chemotherapy was negatively correlated to the SPMs (sHR: 0.847, 95% CI: 0.733‐0.977, P = .023) by conducting competing risk analysis. With chemotherapy, forest plots showed subgroups of squamous cell carcinoma (SCC, sHR: 0.815, 95% CI: 0.7‐0.948, P = .008), 50‐64 years old (sHR:0.794, 95% CI: 0.655‐0.962, P = .019), male (sHR:0.828, 95% CI: 0.703‐0.974, P = .023), and well/moderate histological grade (sHR:0.828, 95% CI: 0.688‐0.996, P = .045) were negatively correlated to SPMs; the nomogram showed the high‐risk population characterized as SCC, elder age, male, and well/moderate histological grade also tended to have lower incidence of SPMs (sHR: 0.805, 95% CI: 0.669‐0.969, P = .022). Despite HNC patients with characteristics of SCC, increased age, male, and well/moderate histological grade had higher risk of a SPM, they were also more likely to be benefitted from chemotherapy to avoid it.

Macrophage‑derived exosomes attenuate the susceptibility of oral squamous cell carcinoma cells to chemotherapeutic drugs through the AKT/GSK‑3β pathway

Although chemotherapy is initially effective in debulking tumor mass in a number of different types of malignancy, tumor cells gradually acquire chemoresistance and frequently progress to advanced clinical stage. Accumulating evidence has indicated that the tumor sensitivity to several chemotherapeutic drugs is regulated by tumor stromal cells including macrophages. However, the role of macrophages in the efficacy of chemotherapeutics on oral squamous cell carcinoma (OSCC) cells is poorly understood. In the present study, the effects of macrophage-secreted exosomes on the sensitivity of OSCC cells towards chemotherapeutic agents were examined. Specifically, the effects of exosomes derived from THP-1 cells and primary human macrophages (PHM) were assessed on the chemosensitivity of OSC-4 cells treated with 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum (CDDP). The THP-1- and PHM-derived exosomes promoted dose-dependent proliferation, decreased the proliferative inhibitory effects of 5-FU and CDDP and decreased apoptosis in OSC-4 cells through activation of the AKT/glycogen synthase kinase-3β signaling pathway. LY294002, a PI3K inhibitor, and MK-2206, an AKT inhibitor, were both able to suppress the observed decrease in sensitivity to chemotherapeutic agents induced by exosomes. Overall, the data from the present study suggested that the macrophage-derived exosomes may decrease the sensitivity to chemotherapeutic agents in OSCC cells. Thus, targeting the interaction between OSCC cells and macrophage-derived exosomes may be considered as a therapeutic approach to improve the chemosensitivity of the tumor microenvironment in oral cancer.

Senescence Induction by Combined Ionizing Radiation and DNA Damage Response Inhibitors in Head and Neck Squamous Cell Carcinoma Cells

DNA damage response inhibitors (DDRi) may selectively enhance the inactivation of tumor cells in combination with ionizing radiation (IR). The induction of senescence may be the key mechanism of tumor cell inactivation in this combinatorial treatment. In the current study the effect of combined IR with DDRi on the induction of senescence was studied in head and neck squamous cell carcinoma (HNSCC) cells with different human papilloma virus (HPV) status. The integrity of homologous recombination (HR) was assessed in two HPV positive, two HPV negative HNSCC, and two healthy fibroblast cell cultures. Cells were treated with the DDRi CC-115 (DNA-dependent protein kinase, DNA-pK; dual mammalian target of rapamycin, mTor), VE-822 (ATR; ataxia telangiectasia and Rad3-related kinase), and AZD0156 (ATM; ataxia telangiectasia mutated kinase) combined with IR. Effects on senescence, apoptosis, necrosis, and cell cycle were analyzed by flow cytometry. The fibroblast cell lines generally tolerated IR or combined treatment better than the tumor cell lines. The ATM and ATR inhibitors were effectively inducing senescence when combined with IR. The DNA-PK inhibitor was not an important inductor of senescence. HPV status and HR activity had a limited influence on the efficacy of DDRi. Induction of senescence and necrosis varied individually among the cell lines due to molecular heterogeneity and the involvement of DNA damage response pathways in senescence induction.

Hypermethylation status of DAPK, MGMT and RUNX3 in HPV negative oral and oropharyngeal squamous cell carcinoma

Squamous cell carcinoma of the oral cavity and oropharynx is the sixth most common type of cancer in the world. During tumorigenesis, gene promoter hypermethylation is considered an important mechanism of transcription silencing of tumor suppressor genes, such as DAPK, MGMT and RUNX3. These genes participate in signaling pathways related to apoptosis, DNA repair and proliferation whose loss of expression is possibly associated with cancer development and progression. In order to investigate associations between hypermethylation and clinicopathological and prognostic parameters, promoter methylation was evaluated in 72 HPV negative oral and oropharyngeal tumors using methylation-specific PCR. Hypermethylation frequencies found for DAPK, MGMT and RUNX3 were 38.88%, 19.44% and 1.38% respectively. Patients with MGMT hypermethylation had a better 2-year overall survival compared to patients without methylation. Being MGMT a repair gene for alkylating agents, it could be a biomarker of treatment response for patients who are candidates for cisplatin chemotherapy, predicting drug resistance. In view of the considerable levels of hypermethylation in cancer cells and, for MGMT, its prognostic relevance, DAPK and MGMT show potential as epigenetic markers, in a way that additional studies may test its viability and efficacy in clinical management.

Valproic Acid Synergizes With Cisplatin and Cetuximab in vitro and in vivo in Head and Neck Cancer by Targeting the Mechanisms of Resistance

Recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC) is a devastating malignancy with a poor prognosis. The combination of cisplatin (CDDP) plus cetuximab (CX) is one of the standard first-line treatments in this disease. However, this therapeutic regimen is often associated with high toxicity and resistance, suggesting that new combinatorial strategies are needed to improve its therapeutic index. In our study, we evaluated the antitumor effects of valproic acid (VPA), a well-known antiepileptic agent with histone deacetylase inhibitory activity, in combination with CDDP/CX doublet in head and neck squamous cell carcinoma (HNSCC) models. We demonstrated, in HNSCC cell lines, but not in normal human fibroblasts, that simultaneous exposure to equitoxic doses of VPA plus CDDP/CX resulted in a clear synergistic antiproliferative and pro-apoptotic effects. The synergistic antitumor effect was confirmed in four different 3D-self-assembled spheroid models, suggesting the ability of the combined approach to affect also the cancer stem cells compartment. Mechanistically, VPA enhanced DNA damage in combination treatment by reducing the mRNA expression of ERCC Excision Repair 1, a critical player in DNA repair, and by increasing CDDP intracellular concentration via upregulation at transcriptional level of CDDP influx channel copper transporter 1 and downregulation of the ATPAse ATP7B involved in CDDP-export. Valproic acid also induced a dose-dependent downregulation of epidermal growth factor receptor (EGFR) expression and of MAPK and AKT downstream signaling pathways and prevent CDDP- and/or CX-induced EGFR nuclear translocation, a well-known mechanism of resistance to chemotherapy. Indeed, VPA impaired the transcription of genes induced by non-canonical activity of nuclear EGFR, such as cyclin D1 and thymidylate synthase. Finally, we confirmed the synergistic antitumor effect also in vivo in both heterotopic and orthotopic models, demonstrating that the combined treatment completely blocked HNSCC xenograft tumors growth in nude mice. Overall, the introduction of a safe and generic drug such as VPA into the conventional treatment for R/M HNSCC represents an innovative and feasible antitumor strategy that warrants further clinical evaluation. A phase II clinical trial exploring the combination of VPA and CDDP/CX in R/M HNSCC patients is currently ongoing in our institute.

Evaluation of antioxidant network proteins as novel prognostic biomarkers for head and neck cancer patients

OBJECTIVES

Recurrence rates for head and neck squamous cell carcinoma (HNSCC) approach 50% at 5 years. Current staging fails to identify patients with a worse prognosis who might benefit from intensified treatment, which warrants improved prognostic biomarkers. The purpose of this retrospective case study is to identify potential prognostic biomarkers in patients with HNSCC including APE1 (DNA repair/redox gene regulator), NRF2 and PPARGC1A (redox gene regulators), SOD3 and DCN (antioxidant proteins).

MATERIALS AND METHODS

Differential protein expression between benign, carcinoma in situ (CIS), and invasive HNSCC tissue specimens from 77 patients was assessed using immunohistochemistry. Protein expression was analyzed with multivariate, pair-wise, and Kaplan-Meier survival analyses to identify potential prognostic biomarkers. Utilizing The Cancer Genome Atlas's transcriptome database, pair-wise and survival analysis was performed to identify potential prognostic biomarkers.

RESULTS

APE1, NRF2, PPARGC1A, SOD3, and DCN expression in HNSCC in relation to, lymph node invasion, and patient survival were examined. Elevated APE1 protein expression in CIS corresponded with reduced survival (p = 0.0243). Increased APE1 gene expression in stage T4a HNSCC was associated with reduced patient survival (p < 0.015). Increased PPARGC1A in invasive tumor correlated with reduced survival (p = 0.0281). Patients with lymph node invasion at diagnosis had significantly increased APE1 protein in the primary sites (p < 0.05). Patients with poorly differentiated invasive tumors had reduced PPARGC1A in CIS proximal to the invasive tumor and had elevated DCN and SOD3 in proximal benign tissue (p < 0.05).

CONCLUSIONS

The expression of APE1, DCN, and SOD3 is a potential prognostic signature that identifies patients with worsened survival.

Anti-Proliferative Effect of Statins Is Mediated by DNMT1 Inhibition and p21 Expression in OSCC Cells

Statins, also known as HMG-CoA reductase inhibitors, are a class of cholesterol-lowering drugs and their anti-cancer effects have been studied in different types of malignant diseases. In the present study, we investigated the anti-proliferative effects of statins, including cerivastatin and simvastatin, on oral squamous cell carcinoma (OSCC) cells. Our data showed that statins inhibited the proliferation of three OSCC cell lines in a dose-dependent manner and this growth inhibition was confirmed through G0/G1 cell cycle arrest. Accordingly, we found the upregulation of p21 and downregulation of cyclin-dependent kinases, including CDK2, CDK4, and CDK6, in the statin-treated cells. Importantly, we clearly showed that statins were able to inhibit the expression of DNA methyltransferase 1 (DNMT1) and further promote the expression of p21. Taken together, our data demonstrated that the anti-proliferative effect of statins is mediated by suppressing DNMT1 expression, thus promoting p21 expression and leading to G0/G1 cell cycle arrest in OSCC cells.

Entinostat is a novel therapeutic agent to treat oral squamous cell carcinoma

INTRODUCTION

Alterations of the epigenome may influence cancer initiation and progression. At the cellular level, histones are key regulators of chromatin accessibility and gene transcription; thus, the inhibition of histone deacetylase enzymes (HDACs) constitutes an attractive target for therapy. In this study, we investigated the effects of the HDAC inhibitor entinostat on oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

We tested the effects of entinostat on OSCC cell lines. Cell viability and growth were analyzed using MTT assay. Cell cycle analysis, cell apoptosis, cancer stem cell (CSC) content, and the concentration of reactive oxygen species (ROS) in OSCC tumor cells were assessed using flow cytometry. The expression of histones and cell cycle regulatory proteins was examined by Western blot.

RESULTS

The administration of entinostat resulted in reduced proliferation of OSCC cells, followed by cell cycle arrest at the G0/G1 phase, as well as substantial tumor apoptosis. We found an increase in ROS production and significant reductions in CSCs. We also found that entinostat caused increased acetylation histone H3 and histone H4, and changes in the expression of cell cycle-associated proteins such as p21.

CONCLUSION

This study indicates that entinostat is a potential novel therapeutic agent for OSCC by halting tumor proliferation, inducing cytotoxicity and intracellular ROS, and attacking the CSCs.

PTBP1 modulates osteosarcoma chemoresistance to cisplatin by regulating the expression of the copper transporter SLC31A1

Chemoresistance is the main obstacle of treatment in patients with osteosarcoma. RNA‐binding protein PTBP1 has been identified as an oncogene in various cancers. However, the role of PTBP1 in osteosarcoma, especially in chemoresistant osteosarcoma, and the underlying mechanism remain unclear. In this study, we aimed to explore the functions of PTBP1 in chemoresistance of osteosarcoma. We found that PTBP1 was significantly increased in chemotherapeutically insensitive osteosarcoma tissues and cisplatin‐resistant osteosarcoma cell lines (MG‐63_CISR and U‐2OS_CISR) as compared to chemotherapy‐sensitive osteosarcoma tissues and cell lines. Knock‐down of PTBP1 can enhance the anti‐proliferation and apoptosis‐induced effects of cisplatin in MG‐63_CISR and U‐2OS_CISR cells. Moreover, PTBP1 knock‐down significantly up‐regulated the expression of the copper transporter SLC31A1, as indicated by transcriptome sequencing. Through RNA immunoprecipitation, dual‐luciferase reporter assay and RNA stability detection, we confirmed that PTBP1 binds to SLC31A1 mRNA and regulates the expression level of SLC31A1 by affecting mRNA stability. Additionally, SLC31A1 silencing abrogated the chemosensitizing effect of PTBP1 knock‐down in MG‐63_CISR and U‐2OS_CISR cells. Using a nude mouse xenograft model, we further confirmed that PTBP1 knock‐down enhanced chemoresistant osteosarcoma responsiveness to cisplatin treatment in vivo. Collectively, the present study suggests that PTBP1 is a crucial determinant of chemoresistance in osteosarcoma.

Epigenetic Modification of CFTR in Head and Neck Cancer

Cystic fibrosis transmembrane conductance regulator (CFTR), a cyclic AMP (cAMP)-regulated chloride channel, is critical for secretion and absorption across diverse epithelia. Mutations or absence of CFTR result in pathogeneses, including cancer. While CFTR has been proposed as a tumor suppressing gene in tumors of the intestine, lung, and breast cancers, its effects in head and neck cancer (HNC) have yet to be investigated. This study aimed to define expression patterns and epigenetic modifications of CFTR in HNC. CFTR was expressed in normal but not in HNC cells and tissues. Treatment with 5-aza-2'-deoxycytidine (5-Aza-CdR) was associated with rescued expression of CFTR, whose function was confirmed by patch clamp technique. Further experiments demonstrated that CFTR CpG islands were hypermethylated in cancer cells and tissues and hypomethylated in normal cells and tissue. Our results suggest that CFTR epigenetic modifications are critical in both down-regulation and up-regulation of CFTR expression in HNC and normal cells respectively. We then investigated the impact of CFTR on expressions and functions of cancer-related genes. CFTR silencing was closely associated with changes to other cancer-related genes, suppressing apoptosis while enhancing proliferation, cell motility, and invasion in HNC. Our findings demonstrate that hypermethylation of CFTR CpG islands and CFTR deficiency is closely related to HNC.

Prognostic value of epithelial-mesenchymal transition-inducing transcription factors in head and neck squamous cell carcinoma: A meta-analysis

Epithelial-mesenchymal transition (EMT) plays a critical role in cancer progression and is primarily regulated by several EMT-inducing transcription factors (EMT-TFs), including TWIST1, TWIST2, SNAI1, SNAI2, ZEB1, and ZEB2. However, the prognostic value of EMT-TFs remains controversial in head and neck squamous cell carcinoma (HNSCC). Studies on the prognostic role of EMT-TFs in HNSCC were searched for in the Web of Science, Science Direct, Proquest, EMBASE, PubMed, and Cochrane Library. Meta-analysis was performed by using Revman 5.2 software. The pooled analysis showed that overexpression of EMT-TFs indicated a poor overall survival (OS) (HR = 1.93, 95% CI = 1.67-2.23) of HNSCC. Subgroup analysis for individual EMT-TFs revealed that overexpression of TWIST1 (HR = 1.61, 95% CI = 1.29-2.02), SNAI1 (HR = 2.17, 95% CI = 1.63-2.88), SNAI2 (HR = 1.90, 95% CI = 1.38-2.62), and ZEB1 (HR = 2.70, 95% CI = 1.61-4.53) were significantly associated with poor OS of HNSCC. These findings support the hypothesis that overexpression of EMT-TFs indicates a poor prognosis for HNSCC patients.

Knockdown of SET Domain, Bifurcated 1 suppresses head and neck cancer cell viability and wound-healing ability in vitro

Head and neck cancer (HNC) is the sixth most common cancer worldwide and therefore presents a global public health problem. There are no standard algorithms for the diagnosis and follow-up of the disease, and no effective current treatment approaches exist. Therefore, the discovery of new biomolecules and the design of new strategies to aid in early diagnosis is necessary, along with establishing prognostic factors of HNC. In several cancer studies, the upregulation of SET Domain, Bifurcated 1 (SETDB1) has been reported to be tumor-inducing and to indicate a cancer-invasive prognosis, leading to the modulation of genes associated with different signaling pathways; however, the literature is sparse regarding the relationship between SETDB1 and HNC. In our study, three HNC primary cell lines and their corresponding metastatic cell lines were used. The quantitative reverse transcriptase-polymerase chain reaction and western blotting data indicated that the SETDB1 mRNA and protein expression levels were higher in all metastatic cell lines compared to their primary cell lines (P < 0.05 for all). To investigate the role of SETDB1 in HNC biology, in vitro functional analyses were carried out using small interference RNA (siRNA) technology, cell viability, scratch wound-healing, and the caspase-3 activity assay of gene expression of SETDB1 to compare primary and metastatic cell lines of HNC. Metastatic cells were more susceptible to this suppression, which decreased the vitality of cells and their ability of wound-healing and induced level of caspase-3 activity (P < 0.05 for all). This functional study has shown that SETDB1 plays an important role in head and neck carcinogenesis. Therefore, SETDB1 may be an attractive therapeutic target molecule and also a potential diagnostic and prognostic biomarker in HNC.

Epigenetic Modifications in Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common human malignancy in the world, with high mortality and poor prognosis for patients. Among the risk factors are tobacco and alcohol intake, human papilloma virus, and also genetic and epigenetic modifications. Many studies show that epigenetic events play an important role in HNSCC development and progression, including DNA methylation, chromatin remodeling, histone posttranslational covalent modifications, and effects of non-coding RNA. Epigenetic modifications may influence silencing of tumor suppressor genes by promoter hypermethylation, regulate transcription by microRNAs and changes in chromatin structure, or induce genome instability through hypomethylation. Moreover, getting to better understand aberrant patterns of methylation may provide biomarkers for early detection and diagnosis, while knowledge about target genes of microRNAs may improve the therapy of HNSCC and extend overall survival. The aim of this review is to present recent studies which demonstrate the role of epigenetic regulation in the development of HNSCC.

A High-Content Screening Approach to Identify MicroRNAs Against Head and Neck Cancer Cell Survival and EMT in an Inflammatory Microenvironment

Head and neck squamous cell carcinoma (HNSCC) is among the most common cancer types. Metastasis, the main cause of death by cancer, can be promoted by an inflammatory microenvironment, which induces epithelial-mesenchymal transition (EMT) through a NF-κB-mediated stabilization of Snail. Here, we aimed to explore how microRNAs (miRs) can affect cell survival and EMT in HNSCC cells under an inflammatory microenvironment. By using a high-content screening (HCS) approach, we evaluated alterations in morphometric parameters, as well as expression/localization of Snail/Slug, in HNSCC cells primed with TNF-α. Based on those quantitation, we established the optimal experimental conditions of EMT induction driven by TNF-α. Those conditions were applied to cells transfected with distinct miRs (N = 31), followed by clusterization of miRs based on alterations related to cell survival and EMT. The signaling pathways enriched with molecular targets from each group of miRs were identified by in silico analyses. Finally, cells were transfected with siRNAs against signaling pathways targeted by miRs with anti-survival/EMT effect and evaluated for alterations in cell survival and EMT. Overall, we observed that TNF-α, at 20 ng/ml, induced EMT-related changes in cell morphology, Snail/Slug expression, and cell migration. Predicted targets of miRs with anti-survival/EMT effect were enriched with targets of NF-κB, PI3K/ATK, and Wnt/beta catenin pathways. Strikingly, individual gene silencing of elements from those pathways, namely RELA (NF-kB), AKT1 (PI3K/AKT), and CTNNB1 (Wnt/beta catenin) reduced cell survival and/or expression of Snail/Slug in cells stimulated with TNF-α. As a whole, our HCS approach allowed for the identification of miRs capable of inhibiting cell survival and EMT considering the presence of an inflammatory microenvironment, also indicating the common signaling pathways and molecular targets most likely to underlie those alterations. These findings may contribute to the development of targeted therapies against HNSCC.

Altered DNA methylation is associated with aberrant stemness gene expression in early‑stage HNSCC

Head and neck squamous cell carcinoma (HNSCC) is characterized by morphological and functional cellular heterogeneity, which are properties of progenitor cells, as opposed to cell alterations caused by accidental expression of stem cell‑related molecules. The expression levels of stemness molecules and their distribution in HNSCC are unclear. As regards sporadic cellular heterogeneity, methylation is an important factor for transcriptional regulation in tumors. Integrative screening analysis of mRNA expression and altered methylation status was performed with original microarrays in 12 tumor and non‑tumor pairs of oral squamous cell carcinoma (SCC) cases. From this data set, genes regulated via aberrant DNA methylation and classified proteins were validated by function clustering. Olfactomedin 4 (OLFM4), known as an intestinal stemness molecule and cell‑cell adhesion factor, was found to be highly expressed in tumors, with an mRNA expression ratio [tumor/normal (T/N)] of 40.7686 and low methylation (‑18.02%) in the promoter region. In addition, the OLFM4 expression levels increased following treatment with the demethylating agent 5‑azacytidine in two HNSCC cell lines. Furthermore, the expression levels of OLFM4 in 59 cases of early‑stage tongue SCC were analyzed using immunohistochemistry to examine protein expression corresponding to the histopathological definition of tumors and to evaluate prognosis. The aberrant stemness gene expression caused by altered DNA methylation appeared to regulate early‑stage HNSCC characteristics. The results of the present study indicated a correlation between OLFM4 expression and promoter methylation, and suggest that it plays an important role in tumor cell heterogeneity in HNSCC.

Interference with the bromodomain epigenome readers drives p21 expression and tumor senescence

Head and neck cancer (HNSCC) are one of the most common solid malignancies of the world, being responsible for over 350,000 deaths every year. Much of the complications in managing and treating HNSCC advent from the complex genetic and epigenetic landscape of the disease. Emerging information has shown promising results in targeting BRD4, an epigenetic regulator bromodomain that functions as a scaffold for transcription factors at promoters and super-enhancers. Here we show that by disrupting the interaction between BRD4 and histones using the bromodomain inhibitor JQ1, HNSCC cells undergo cell growth arrest followed by cellular senescence. Mechanistically, JQ1 negatively impacted the phosphorylation levels of SIRT1 along with the acetylation levels of mutant p53 (active). In vivo administration of JQ1 resulted in disruption of HNSCC growth along with the activation of cellular senescence, observed by the accumulation of DNA double-strand breaks, p16^ink4, accumulation of senescence-associated beta-galactosidase, and loss of phosphorylated Sirt1^ser47. Furthermore, we also demonstrate that JQ1 was efficient in reducing the population of cancer stem cells from HNSCC xenografts.

SIRT1: a potential tumour biomarker and therapeutic target

SIRT1, which is highly homologous to yeast silent information regulator 2, has recently garnered tremendous attention because of its various regulatory effects in several pathological conditions. Numerous studies have found that SIRT1 is highly expressed in a broad range of tumours compared with the paracancerous tissue. However, the role of SIRT1 in malignancies has yet to be systematically elucidated, and its use as a promising biomarker or therapeutic target for tumours has not been well-reported. Herein, we focus on the roles of SIRT1 in cancers and summarise the potential use of SIRT1 as a promising tumour biomarker or therapeutic target.

Identification of Novel MicroRNAs and Their Diagnostic and Prognostic Significance in Oral Cancer

Background: Oral cancer is one of the most prevalent cancers worldwide. Despite that the oral cavity is easily accessible for clinical examinations, oral cancers are often not promptly diagnosed. Furthermore, to date no effective biomarkers are available for oral cancer. Therefore, there is an urgent need to identify novel biomarkers able to improve both diagnostic and prognostic strategies. In this context, the development of innovative high-throughput technologies for molecular and epigenetics analyses has generated a huge amount of data that may be used for the identification of new cancer biomarkers. Methods: In the present study, GEO DataSets and TCGA miRNA profiling datasets were analyzed in order to identify miRNAs with diagnostic and prognostic significance. Furthermore, several computational approaches were adopted to establish the functional roles of these miRNAs. Results: The analysis of datasets allowed for the identification of 11 miRNAs with a potential diagnostic role for oral cancer. Additionally, eight miRNAs associated with patients' prognosis were also identified; six miRNAs predictive of patients' overall survival (OS) and one, hsa-miR-let.7i-3p, associated with tumor recurrence. Conclusion: The integrated analysis of different miRNA expression datasets allows for the identification of a set of miRNAs that, after validation, may be used for the early detection of oral cancers.

Differential Activation of ERK Signaling in HPV-Related Oropharyngeal Squamous Cell Carcinoma

Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) forms a distinct tumor entity with better survival clinical outcome. Numerous underlying molecular mechanisms have been postulated for differences in treatment response, but the impact of MEK/ERK signaling, a main driver of carcinogenesis in various cancers including OPSCC and key player mediating therapy resistance remains elusive. In a retrospective experimental cohort study, primary tumor samples from OPSCC patients (n = 124) were available on tissue microarrays (TMAs) and expression levels of phosphorylated ERK1/2 (pERK1/2) were detected by immunohistochemical staining. Correlations of pERK1/2 expression patterns with clinicopathological features and clinical outcome were evaluated by statistical analysis. A low pERK1/2 expression was strongly associated with HPV-related OPSCC, while primary tumors with high pERK1/2 staining showed a distinctly worse survival outcome and were associated with higher cellular differentiation. Co-activation of both ERK1/2 and AKT was a common event and was associated with unfavorable prognosis in our cohort. However, the combinatorial analysis of pAKT (Ser473) and pERK1/2 did not strengthen the predictive power of pERK1/2, suggesting that pERK1/2 plays a more significant function in OPSCC. In summary, our data provide a compelling experimental and statistical evidence that low levels of tumor cell intrinsic ERK1/2 activation contribute at least in part to the favorable outcome of HPV-related OPSCC. On the other hand, presented findings indicate that non-HPV-related OPSCC with elevated ERK phosphorylation are at high risk for treatment failure and might benefit from targeted therapy of MEK/ERK signaling.

A History of Innovations in the Diagnosis and Treatment of Oral and Head and Neck Cancer

Historical records as far back as 3000 BCE show that oral and head and neck cancer was a disease process well known to Egyptian physicians. Luminaries such as Hippocrates, Galen, Pott, and Virchow were instrumental in shaping our understanding of the etiology and pathogenesis of cancer. During the 20th century, evidence-based medicine catalyzed the development of rigorous science-based diagnostic and treatment protocols. The use of surgery, therapeutic radiation, and chemotherapy as single-treatment agents or in combination with one another gradually emerged as the preferred approach to cancer therapy. The recognition of tobacco, alcohol, and human papillomavirus as etiological agents in oral and head and neck cancer prompted the development of new diagnostic aids and treatment strategies to mitigate cancer progression. More in-depth mechanistic insights into the multistep process of oral and head and neck cancer were made possible by the use of the hamster buccal pouch and mouse models. New technologies, such as the sequencing of the human genome, metabolomics, and proteomics, have provided the foundation for what we today call precision medicine. The future success of tailored medical treatment for cancer patients will depend on the discovery of new druggable targets with improved therapeutic efficacy. As the precision and sensitivity of existing tools for prevention and risk assessment improve, greater accuracy will be achieved in predicting health outcomes.

Systems Biology Approaches and Precision Oral Health: A Circadian Clock Perspective

A vast majority of the pathophysiological and metabolic processes in humans are temporally controlled by a master circadian clock located centrally in the hypothalamic suprachiasmatic nucleus of the brain, as well as by specialized peripheral oscillators located in other body tissues. This circadian clock system generates a rhythmical diurnal transcriptional-translational cycle in clock genes and protein expression and activities regulating numerous downstream target genes. Clock genes as key regulators of physiological function and dysfunction of the circadian clock have been linked to various diseases and multiple morbidities. Emerging omics technologies permits largescale multi-dimensional investigations of the molecular landscape of a given disease and the comprehensive characterization of its underlying cellular components (e.g., proteins, genes, lipids, metabolites), their mechanism of actions, functional networks and regulatory systems. Ultimately, they can be used to better understand disease and interpatient heterogeneity, individual profile, identify personalized targetable key molecules and pathways, discover novel biomarkers and genetic alterations, which collectively can allow for a better patient stratification into clinically relevant subgroups to improve disease prediction and prevention, early diagnostic, clinical outcomes, therapeutic benefits, patient's quality of life and survival. The use of “omics” technologies has allowed for recent breakthroughs in several scientific domains, including in the field of circadian clock biology. Although studies have explored the role of clock genes using circadiOmics (which integrates circadian omics, such as genomics, transcriptomics, proteomics and metabolomics) in human disease, no such studies have investigated the implications of circadian disruption in oral, head and neck pathologies using multi-omics approaches and linking the omics data to patient-specific circadian profiles. There is a burgeoning body of evidence that circadian clock controls the development and homeostasis of oral and maxillofacial structures, such as salivary glands, teeth and oral epithelium. Hence, in the current era of precision medicine and dentistry and patient-centered health care, it is becoming evident that a multi-omics approach is needed to improve our understanding of the role of circadian clock-controlled key players in the regulation of head and neck pathologies. This review discusses current knowledge on the role of the circadian clock and the contribution of omics-based approaches toward a novel precision health era for diagnosing and treating head and neck pathologies, with an emphasis on oral, head and neck cancer and Sjögren's syndrome.

Combined class I histone deacetylase and mTORC1/C2 inhibition suppresses the initiation and recurrence of oral squamous cell carcinomas by repressing SOX2

Treatment of oral squamous cell carcinoma (OSCC) remains a challenge because of the lack of effective early treatment strategies and high incidence of relapse. Here, we showed that combined 4SC-202 (a novel selective class I HDAC inhibitor) and INK128 (a selective mTORC1/C2 inhibitor) treatment exhibited synergistic effects on inhibiting cell growth, sphere-forming ability, subcutaneous tumor formation and ALDH1⁺ cancer stem cells (CSCs) in OSCC. The initiation of OSCC was significantly inhibited by combined treatment in 4NQO-induced rat model. In addition, upregulated SOX2 was associated with advanced and metastatic tumors in OSCC patients and was responsible for the drug-resistance property of OSCC cells. The inhibitory effect of combined treatment on cell viability and ALDH1⁺ CSCs were attenuated by SOX2 verexpression. Furthermore, combined treatment can effectively overcome chemoresistance and inhibit the growth of recurrent OSCC in vitro and in vivo. Mechanistically, 4SC-202 and INK128 repressed SOX2 expression through miR-429/miR-1181-mediated mRNA degradation and preventing cap-dependent mRNA translation, respectively. These results suggest that combined class I histone deacetylase and mTORC1/C2 inhibition suppresses the carcinogenesis and recurrence of OSCC by repressing SOX2.

Molecular Biomarkers Related to Oral Carcinoma: Clinical Trial Outcome Evaluation in a Literature Review

Backgrounds

The objective of the present research was to systematically revise the international literature about the genetic biomarkers related to oral cancer (OC) evaluating the recent findings in clinical studies.

Methods

A comprehensive review of the current literature was conducted according to the PRISMA guidelines by accessing the NCBI PubMed database. The authors conducted the search of articles in the English language published from 2008 to 2018. The present systematic review included only papers with significant results about correlation between wound healing, genetic alteration, and OC. Prognostic capacity of genetic markers was not evaluated in vivo.

Results

The first analysis with filters recorded about 1884 published papers. Beyond reading and consideration of suitability, only 20 and then 8 papers, with case report exclusion, were recorded for the revision.

Conclusion

All the researches recorded the proteomic and genetic alterations in OC human biopsy cells. The gene modification level in the different studies, compared with samples of healthy tissues, has always been statistically significant, but it is not possible to associate publications with each other because each job is based on the measurement of different biomarkers and gene targets. Further investigations should be required in order to state scientific evidence about a clear advantage of using these biomarkers for diagnostic purpose.

Sleep and Neurochemical Modulation by DZNep and GSK-J1: Potential Link With Histone Methylation Status

Histone methylation/demethylation plays an important modulatory role in chromatin restructuring, RNA transcription and is essential for controlling a plethora of biological processes. Due to many human diseases have been related to histone methylation/demethylation, several compounds such as 3-deazaneplanocin A (DZNep) or 3-((6-(4,5-Dihydro-1H-benzo[d]azepin-3(2H)-yl)-2-(pyridin-2-yl)pyrimidin-4-yl)amino)propanoic acid; N-[2-(2-pyridinyl)-6-(1,2,4,5-tetrahydro-3H-3-benzazepin-3-yl)-4-pyrimidinyl]-β-Alanine (GSK-J1), have been designed to inhibit histone methylase or suppress histone demethylase, respectively. In the present study, we investigated the effects on the sleep-wake cycle and sleep-related neurochemical levels after systemic injections of DZNep or GSK-J1 given during the light or dark phase in rats. DZNep dose-dependently (0.1, 1.0, or 10 mg/kg, i.p.) prolonged wakefulness (W) duration while decreased slow wave sleep (SWS) and rapid eye movement sleep (REMS) time spent during the lights-on period with no changes observed in dark phase. In opposite direction, GSK-J1 (0.1, 1.0, or 10 mg/kg, i.p.) injected at the beginning of the lights-on period induced no statistical changes in W, SWS, or REMS whereas if administered at darkness, we found a diminution in W and an enhancement in SWS and REMS. Finally, brain microdialysis experiments in freely moving animals were used to evaluate the effects of DZNep or GSK-J1 treatments on contents of sleep-related neurochemicals. The results showed that DZNep boosted extracellular levels of dopamine, norepinephrine, epinephrine, serotonin, adenosine, and acetylcholine if injected at the beginning of the lights-on period whereas GSK-J1 exerted similar outcomes but when administered at darkness. In summary, DZNep and GSK-J1 may control the sleep-wake cycle and sleep-related neurochemicals through histone methylation/demethylation activity.

Not Everyone Fits the Mold: Intratumor and Intertumor Heterogeneity and Innovative Cancer Drug Design and Development

Disruptive innovations in medicine are game-changing in nature and bring about radical shifts in the way we understand human diseases, their treatment, and/or prevention. Yet, disruptive innovations in cancer drug design and development are still limited. Therapies that cure all cancer patients are in short supply or do not exist at all. Chief among the causes of this predicament is drug resistance, a mechanism that is much more dynamic than previously understood. Drug resistance has limited the initial success experienced with biomarker-guided targeted therapies as well. A major contributor to drug resistance is intratumor heterogeneity. For example, within solid tumors, there are distinct subclones of cancer cells, presenting profound complexity to cancer treatment. Well-known contributors to intratumor heterogeneity are genomic instability, the microenvironment, cellular genotype, cell plasticity, and stochastic processes. This expert review explains that for oncology drug design and development to be more innovative, we need to take into account intratumor heterogeneity. Initially thought to be the preserve of cancer cells, recent evidence points to the highly heterogeneous nature and diverse locations of stromal cells, such as cancer-associated fibroblasts (CAFs) and cancer-associated macrophages (CAMs). Distinct subpopulations of CAFs and CAMs are now known to be located immediately adjacent and distant from cancer cells, with different subpopulations exerting different effects on cancer cells. Disruptive innovation and precision medicine in clinical oncology do not have to be a distant reality, but can potentially be achieved by targeting these spatially separated and exclusive cancer cell subclones and CAF subtypes. Finally, we emphasize that disruptive innovations in drug discovery and development will likely come from drugs whose effect is not necessarily tumor shrinkage.

5-Aza-CdR promotes partial MGMT demethylation and modifies expression of different genes in oral squamous cell carcinoma

OBJECTIVE

Treatment strategies for oral squamous cell carcinoma (OSCC) vary, depending on the stage of diagnosis. Surgery and radiotherapy are options for localized lesions for stage I patients, whereas chemotherapy is the main treatment for metastatic OSCC. However, aggressive tumors can relapse, frequently causing death. In an attempt to address this, novel treatment protocols using drugs that alter the epigenetic profile have emerged as an alternative to control tumor growth and metastasis. Therefore, the objective in this study was to investigate the effect of the demethylating drug 5-aza-CdR in SCC9 OSCC cells.

STUDY DESIGN

SCC9 cells were treated with 5-Aza-CdR at concentrations of 0.3μM and 2μM for 24hours and 48hours. DNA methylation of the MGMT, BRCA1, APC, c-MYC, and hTERT genes were investigated by using the methylation-specific high-resolution melting technique. Real time-polymerase chain reaction and quantitative polymerase chain reaction were performed to analyze gene expression.

RESULTS

5-Aza-CdR promoted demethylation of MGMT and modified the transcription of all analyzed genes. Curiously, 5-aza-CdR at the concentration of 0.3μM was more efficient than 2μM in SCC9 cells.

CONCLUSIONS

We observed that 5-aza-CdR led to MGMT demethylation, upregulated the transcription of 3 important tumor suppressor genes, and promoted the downregulation of c-Myc.

Interfering with bromodomain epigenome readers as therapeutic option in mucoepidermoid carcinoma

PURPOSE

Emerging evidence indicates that bromodomains comprise a conserved class of epigenome readers involved in cancer development and inflammation. Bromodomains are associated with epigenetic modifications of gene transcription through interactions with lysine residues of histone tails. Particularly, the bromodomain and extra-terminal domain (BET) family member BRD4 has been found to be involved in the control over oncogenes, including c-MYC, and in the maintenance of downstream inflammatory processes. The objective of this study was to evaluate the effect of pharmacologically displacing BRD4 in mucoepidermoid carcinoma (MEC) cells.

METHODS

We assessed the presence of BRD4 levels in a panel of human MEC tissue samples in conjunction with histological grading and clinical information. In vitro studies were carried out using human MEC-derived cell lines. The BET inhibitor iBET762 was administered to MEC cells to assess the impact of disrupted BRD4 signaling on colony forming capacities and cell cycle status. The activation of cellular senescence induced by iBET762 was determined by immunohistochemical staining for p16^ink4. Flow cytometry was used to identify populations of cancer stem cells in MEC-derived cell lines.

RESULTS

We found that primary human MECs and MEC-derived cell lines are endowed with high BRD4 expression levels compared to those in normal salivary glands. We also found that, by displacing BRD4 from chromatin using the BET inhibitor iBET762, MEC cells lose their colony forming capacities and undergo G1 cell cycle arrest and senescence. Finally, we found that targeted displacement of BRD4 from chromatin results in depletion of cancer stem cells from the overall MEC cell populations.

CONCLUSIONS

Our findings indicate that bromodomain-mediated gene regulation constitutes an epigenetic mechanism that is deregulated in MEC cells and that the use of BET inhibitors may serve as a feasible therapeutic strategy to manage MECs.