Molecular Patterns and Biology of HPV-Associated HNSCC

The Role of Biomarkers in HPV-Positive Head and Neck Squamous Cell Carcinoma: Towards Precision Medicine

Head and neck cancer (HNC) represents a significant global health challenge, with squamous cell carcinomas (SCCs) accounting for approximately 90% of all HNC cases. These malignancies, collectively referred to as head and neck squamous cell carcinoma (HNSCC), originate from the mucosal epithelium lining the larynx, pharynx, and oral cavity. The primary risk factors associated with HNSCC in economically disadvantaged nations have been chronic alcohol consumption and tobacco use. However, in more affluent countries, the landscape of HNSCC has shifted with the identification of human papillomavirus (HPV) infection, particularly HPV-16, as a major risk factor, especially among nonsmokers. Understanding the evolving risk factors and the distinct biological behaviors of HPV-positive and HPV-negative HNSCC is critical for developing targeted treatment strategies and improving patient outcomes in this complex and diverse group of cancers. Accurate diagnosis of HPV-positive HNSCC is essential for developing a comprehensive model that integrates the molecular characteristics, immune microenvironment, and clinical outcomes. The aim of this comprehensive review was to summarize the current knowledge and advances in the identification of DNA, RNA, and protein biomarkers in bodily fluids and tissues that have introduced new possibilities for minimally or non-invasive cancer diagnosis, monitoring, and assessment of therapeutic responses.

p16 and p53 can Serve as Prognostic Markers for Head and Neck Squamous Cell Carcinoma

OBJECTIVE

The present study aimed to explore the expression and clinical significance of human papilloma virus-related pathogenic factors (p16, cyclin D1, p53) in patients with head and neck squamous cell carcinoma (HNSCC) and construct a predictive model.

METHODS

The Cancer Genome Atlas was used to obtain clinical data for 112 patients with HNSCC. Expression of p16, p53, and cyclin D1 was quantified. We used the survival package of the R program to set the cut-off value. Values above the cut-off were considered positive, while values below the cut-off were negative. Kaplan-Meier analysis and univariate and multivariate Cox regression analyses were performed to investigate prognostic clinicopathological indicators and the expression of p16, p53, and cyclin D1. A predictive model was constructed based on the results of multifactor Cox regression analysis, and the accuracy of the predictive model was verified through final calibration analysis. Follow-up of patients with HNSCC at the Affiliated Hospital of Binzhou Medical University was conducted from 2015 to 2017, and reliability of the predictive model was validated based on follow-up data and molecular expression levels.

RESULTS

According to the results, expression of p16 and p53 was significantly associated with prognosis (P < .05). The predictive model constructed based on the expression levels of p16 and p53 was useful for evaluating the prognosis of patients with HNSCC. The predictive model was validated using follow-up data obtained from the hospital, and the trend of the follow-up results was consistent with the predictive model.

CONCLUSION

p16 and p53 can be used as key indicators to predict the prognosis of HNSCC patients and as critical immunohistochemical indicators in clinical practice. The survival model constructed based on p16 and p53 expression levels reliably predicts patient prognosis.

Exploring NK-Cell molecules that impact the immune response and microenvironment in head and neck squamous cell carcinoma

NK cells play a role in various cancers, but their role in head and neck squamous cell carcinoma (HNSCC) still needs to be explored. All public data are obtained from the Cancer Genome Atlas Program (TCGA) database. All analysis was performed using specific packages in R software. In our study, we quantified the immune microenvironment of HNSCC through multiple algorithms. Next, we identified NK cell-associated genes by quantifying NK cells, including SSNA1, TRIR, PAXX, DPP7, WDR34, EZR, PHLDA1 and ELOVL1. Then, we explored the single-cell expression pattern of these genes in the HNSCC microenvironment. Univariate Cox regression analysis indicated that the EZR, PHLDA1 and ELOVL1 were related to the prognosis of HNSCC patients. Following this, we selected EZR for further analysis. Our results showed that the patients with high EZR expression might have a poor prognosis and worse clinical features. Biological enrichment analysis showed that EZR is associated with many oncogenic pathways and a higher tumour stemness index. Meanwhile, we found that EZR can remodel the immune microenvironment of HNSCC. Moreover, we noticed that EZR could affect the immunotherapy and specific drug sensitivity, making it an underlying clinical target. In summary, our results can improve the understanding of NK cell in HNSCC. Meanwhile, we identified EZR as the underlying clinical target of HNSCC.

5'-Ectonucleotidase CD73/NT5E supports EGFR-mediated invasion of HPV-negative head and neck carcinoma cells

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) of malignant cells is a driving force of disease progression in human papillomavirus-negative (HPV-negative) head and neck squamous cell carcinomas (HNSCC). Sustained hyper-activation of epidermal growth factor receptor (EGFR) induces an invasion-promoting subtype of EMT (EGFR-EMT) characterized by a gene signature ("'EGFR-EMT_Signature'") comprising 5´-ectonucleotidase CD73. Generally, CD73 promotes immune evasion via adenosine (ADO) formation and associates with EMT and metastases. However, CD73 regulation through EGFR signaling remains under-explored and targeting options are amiss.

METHODS

CD73 functions in EGFR-mediated tumor cell dissemination were addressed in 2D and 3D cellular models of migration and invasion. The novel antagonizing antibody 22E6 and therapeutic antibody Cetuximab served as inhibitors of CD73 and EGFR, respectively, in combinatorial treatment. Specificity for CD73 and its role as effector or regulator of EGFR-EMT were assessed upon CD73 knock-down and over-expression. CD73 correlation to tumor budding was studied in an in-house primary HNSCC cohort. Expression correlations, and prognostic and predictive values were analyzed using machine learning-based algorithms and Kaplan-Meier survival curves in single cell and bulk RNA sequencing datasets.

RESULTS

CD73/NT5E is induced by the EGF/EGFR-EMT-axis and blocked by Cetuximab and MEK inhibitor. Inhibition of CD73 with the novel antagonizing antibody 22E6 specifically repressed EGFR-dependent migration and invasion of HNSCC cells in 2D. Cetuximab and 22E6 alone reduced local invasion in a 3D-model. Interestingly, combining inefficient low-dose concentrations of Cetuximab and 22E6 revealed highly potent in invasion inhibition, substantially reducing the functional IC50 of Cetuximab regarding local invasion. A role for CD73 as an effector of EGFR-EMT in local invasion was further supported by knock-down and over-expression experiments in vitro and by high expression in malignant cells budding from primary tumors. CD73 expression correlated with EGFR pathway activity, EMT, and partial EMT (p-EMT) in malignant single HNSCC cells and in large patient cohorts. Contrary to published data, CD73 was not a prognostic marker of overall survival (OS) in the TCGA-HNSCC cohort when patients were stratified for HPV-status. However, CD73 prognosticated OS of oral cavity carcinomas. Furthermore, CD73 expression levels correlated with response to Cetuximab in HPV-negative advanced, metastasized HNSCC patients.

CONCLUSIONS

In sum, CD73 is an effector of EGF/EGFR-mediated local invasion and a potential therapeutic target and candidate predictive marker for advanced HPV-negative HNSCC.

Expression and molecular regulation of non-coding RNAs in HPV-positive head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent malignancy worldwide. Accumulating evidence suggests that persistent HPV infection is closely related to a subset of HNSCC types, and the incidence of human papillomavirus (HPV)-positive HNSCC has been annually increasing in recent decades. Although the carcinogenesis of HPV-positive HNSCC has not been completely elucidated, it has been well confirmed that E6 and E7, the main viral oncoproteins are responsible for the maintenance of malignant transformation, promotion of cell proliferation, and increase in tumor invasion. Moreover, compared with HPV-negative HNSCC, HPV-positive HNSCC shows some special clinical-pathological features, which are possibly related to HPV infection and their specific regulatory mechanisms. Non-coding RNA (ncRNA) is a class of RNA lacking the protein-coding function and playing a critical regulatory role via multiple complex molecular mechanisms. NcRNA is an important regulatory pattern of epigenetic modification, which can exert significant effects on HPV-induced tumorigenesis and progression by deregulating downstream genes. However, the knowledge of ncRNAs is still limited, hence, a better understanding of ncRNAs could provide some insights for exploring the carcinogenesis mechanism and identifying valuable biomarkers in HPV-positive HNSCC. Therefore, in this review, we mainly focused on the expression profile of ncRNAs (including lncRNA, miRNA, and circRNA) and explored their regulatory role in HPV-positive HNSCC, aiming to clarify the regulatory mechanism of ncRNAs and identify valuable biomarkers for HPV-positive HNSCC.

Head and Neck Squamous Cell Carcinoma: NT5E Could Be a Prognostic Biomarker

Head and neck squamous cell carcinoma (HNSCC) is a type of tumour with a relatively poor prognosis. In recent years, immune checkpoint inhibitors, such as CTLA-4 and PD-1/PDL-1 inhibitors, have improved the treatment status of advanced tumours. However, the emergence of drug resistance has brought difficulties to clinical treatment, and new immune checkpoint research is imminent. The hypoxia-adenosine pathway, in which CD73 encoded by the NT5E gene is a key enzyme for adenosine production, has been identified as an immune checkpoint of great potential. Therefore, NT5E may play an important role in HNSCC. We performed a detailed bioinformatics analysis of NT5E in HNSCC, and the results showed that the overexpression of NT5E in HNSCC was associated with poor prognosis. Our further investigation of the coexpression pattern of HNSCC could provide a reference for drug resistance and immunotherapy studies.

Clinical variables and magnetic resonance imaging-based radiomics predict human papillomavirus status of oropharyngeal cancer

BACKGROUND

Human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) have better prognosis and treatment response compared to HPV-negative OPSCC. This study aims to noninvasively predict HPV status of OPSCC using clinical and/or radiological variables.

METHODS

Seventy-seven magnetic resonance radiomic features were extracted from T1-weighted postcontrast images of the primary tumor of 153 patients. Logistic regression models were created to predict HPV status, determined with immunohistochemistry, based on clinical variables, radiomic features, and its combination. Model performance was evaluated using area under the curve (AUC).

RESULTS

Model performance showed AUCs of 0.794, 0.764, and 0.871 for the clinical, radiomic, and combined models, respectively. Smoking, higher T-classification (T3 and T4), larger, less round, and heterogeneous tumors were associated with HPV-negative tumors.

CONCLUSION

Models based on clinical variables and/or radiomic tumor features can predict HPV status in OPSCC patients with good performance and can be considered when HPV testing is not available.

EGFR overexpression increases radiotherapy response in HPV-positive head and neck cancer through inhibition of DNA damage repair and HPV E6 downregulation

High-risk Human Papillomavirus (HPV) infections have recently emerged as an independent risk factor in head and neck squamous cell carcinoma (HNSCC). There has been a marked increase in the incidence of HPV-induced HNSCC subtype, which demonstrates different genetics with better treatment outcome. Despite the favourable prognosis of HPV-HNSCC, the treatment modality, consisting of high dose radiotherapy (RT) in combination with chemotherapy (CT), remains similar to HPV-negative tumours, associated with toxic side effects. Epidermal growth factor receptor (EGFR) is overexpressed in over 80% of HNSCC and correlates with RT resistance. EGFR inhibitor Cetuximab is the only FDA approved targeted therapy for both HNSCC subtypes, however the response varies between HNSCC subtypes. In HPV-negative HNSCC, Cetuximab sensitises HNSCC to RT improving survival rates. To reduce adverse cytotoxicity of CT, Cetuximab has been approved for treatment de-escalation of HPV-positive HNSCC. The results of several recent clinical trials have concluded differing outcome to HPV-negative HNSCC. Here we investigated the role of EGFR in HPV-positive HNSCC response to RT. Remarkably, in HPV-positive HNSCC cell lines and in vivo tumour models, EGFR activation was strongly indicative of increased RT response. In response to RT, EGFR activation induced impairment of DNA damage repair and increased RT response. Furthermore, EGFR was found to downregulate HPV oncoproteinE6 expression and induced p53 activity in response to RT. Collectively, our data uncovers a novel role for EGFR in virally induced HNSCC and highlights the importance of using EGFR-targeted therapies in the context of the genetic makeup of cancer.

M2 macrophages reduce the radiosensitivity of head and neck cancer by releasing HB‑EGF

The aim of the present study was to examine the potential role of human heparin‑binding epidermal growth factor (HB‑EGF) secreted by M2 macrophages in the development of radioresistance in head and neck squamous cell carcinoma (HNSCC). Immunohistochemistry was used to detect radiosensitivity in human papilloma virus (HPV)‑positive and HPV‑negative HNSCC tissues and immunohistochemical staining with specific antibodies for macrophage surface markers was used to assess the infiltration of M1 and M2 macrophages in HPV‑positive and ‑negative HNSCC tissues. The expression of HB‑EGF in HPV‑positive and ‑negative HNSCC tissues was determined by multi‑cytokine detection in order to determine the relationship between HB‑EGF and radiosensitivity. M1 and M2 macrophages were co‑cultured with the HNSCC cell line CAL27 and treated with HB‑EGF and its neutralizing antibodies to assess radiation sensitivity. Finally, the major DNA double‑strand break repair pathways required for the activation of HB‑EGF and promotion of epidermal growth factor receptor (EGFR) were identified. The results revealed that radiosensitivity was higher in HPV‑positive HNSCC compared with HPV‑negative. There was a higher infiltration of M2 macrophages in HPV‑negative HNSCC, which were revealed as the main source of HB‑EGF secretion. Furthermore, it was determined that overexpression of HB‑EGF induced radioresistance in HPV‑negative HNSCC. HB‑EGF promoted the activation of the non‑homologous end‑joining pathway by activating EGFR. To the best of our knowledge, this is the first study to demonstrate the association between HB‑EGF and radiosensitivity in HNSCC. These results indicated that the secretion of HB‑EGF by M2 macrophages could induce radioresistance of HPV‑negative HNSCC.

Beyond MicroRNAs: Emerging Role of Other Non-Coding RNAs in HPV-Driven Cancers

Persistent infection with high-risk Human Papilloma Virus (HPV) leads to the development of several tumors, including cervical, oropharyngeal, and anogenital squamous cell carcinoma. In the last years, the use of high-throughput sequencing technologies has revealed a number of non-coding RNA (ncRNAs), distinct from micro RNAs (miRNAs), that are deregulated in HPV-driven cancers, thus suggesting that HPV infection may affect their expression. However, since the knowledge of ncRNAs is still limited, a better understanding of ncRNAs biology, biogenesis, and function may be challenging for improving the diagnosis of HPV infection or progression, and for monitoring the response to therapy of patients affected by HPV-driven tumors. In addition, to establish a ncRNAs expression profile may be instrumental for developing more effective therapeutic strategies for the treatment of HPV-associated lesions and cancers. Therefore, this review will address novel classes of ncRNAs that have recently started to draw increasing attention in HPV-driven tumors, with a particular focus on ncRNAs that have been identified as a direct target of HPV oncoproteins.

Circulating HPV16 DNA may complement imaging assessment of early treatment efficacy in patients with HPV-positive oropharyngeal cancer

Background

Early detection of treatment failure may improve clinical outcome and overall survival in patients with head and neck cancer after first-line treatment. Circulating cell-free HPV16 DNA (cfHPV16 DNA) was evaluated as a possible complementary marker to radiological assessment of early response in patients with HPV-related oropharyngeal cancer (OPC) after radiotherapy alone or combined with chemotherapy.

Methods

The study included 66 patients with HPV-related OPC receiving radical radiotherapy alone or in combination with chemotherapy. cfHPV16 DNA was assessed in the blood of all patients before treatment using TaqMan-based qPCR. Subsequent analysis of cfHPV16 DNA was performed 12 weeks after treatment completion, along with radiological assessment of early treatment results.

Results

Complete (CRR) and incomplete radiological response (IRR) was found in 43 (65%) and 23 (35%) patients respectively. cfHPV16 DNA was present in 5 (28%) patients with IRR, while only in 1 (4%) with CRR. Three of five patients with IRR that were positive for cfHPV16 DNA exhibited histopathologically confirmed local or regional treatment failure, and other two developed distant metastases. None of the patients with negative cfHPV16 DNA presented disease failure.

Conclusion

The post-treatment assessment of cfHPV16 DNA in patients with HPV-related OPC may be used as a complementary biomarker to conventional imaging-based examinations for early identification of treatment failure.

MAGE-A11 Expression Predicts Patient Prognosis in Head and Neck Squamous Cell Carcinoma

Background

Head and neck squamous cell carcinomas (HNSCCs) are the sixth most common cancer worldwide. Growing evidence showed that Melanoma-associated antigen-A11 (MAGE-A11) was abnormally expressed in various malignancies, but MAGE-A11 expression and its biological roles in HNSCC had not been reported in detail. The aim of the study was to investigate the association between MAGE-A11 signatures and clinicopathological features of HNSCC patients and uncover its potential mechanisms in HNSCC patients.

Methods

In the present study, we analyzed the expression of MAGE-A11 gene and evaluated the impact of MAGE-A11 genes expression on clinical outcome from the Cancer Genome Atlas (TCGA) database. MAGE-A11 expression was assessed in a well-characterized series of HNSCC (N = 75) with long-term follow-up and 10 cases of adjacent non-cancerous tissues, which were diagnosed between 2013 and 2014, by using immunohistochemistry. The correlation between MAGE-A11 expression and clinicopathological factors was analyzed. Kaplan-Meier and Cox regression analyses were used to assess the prognostic significance of MAGE-A11 expression among HNSCC patients.

Results

The results showed that MAGE-A11 mRNA expression was increased in HNSCC tissues compared to "normal" tissues (P < 10^-12). MAGE-A11 protein expression was not correlated with lymph node status, relapse, age, gender, histological grade, differentiation, clinical stage, tumor size, radiotherapy or chemotherapy. The patients with high MAGE-A11 expression had lower 5-year overall survival (OS) rates than those with low MAGE-A11 expression as determined using the Kaplan-Meier method. The univariate and multivariate analyses confirmed that elevated MAGE-A11 was an independent prognostic factor for the OS of HNSCC patients.

Conclusion

These findings indicate that MAGE-A11 may be a valuable diagnostic or prognostic marker as well as a potential molecular therapy target for HNSCC patients.

Overexpression of TRMT12 may independently predict poor overall survival in patients with head and neck squamous cell carcinoma

Purpose

The TRMT12 is a novel oncogene involved in breast cancer. However, the association between TRMT12 and head and neck squamous cell carcinoma (HNSCC) remains unclear.

Materials and methods

The levels of TRMT12 mRNA in HNSCC and normal tissues were analyzed using data from the Cancer Genome Atlas-HNSC. The expression of TRMT12 was also determined using quantitative real-time polymerase chain reaction in 165 paired HNSCC and adjacent normal tissues, which were used as the validation cohort.

Results

TRMT12 expression was significantly increased in HNSCC tissues versus normal tissues. High TRMT12 expression was significantly associated with human papillomavirus infection, perineural invasion, tumor invasion, lymphatic metastasis, and clinical stage. Moreover, elevated TRMT12 expression was correlated with unfavorable overall survival (hazard ratio [HR]: 1.711, 95% confidence interval [CI]: 1.141-2.567, P=0.009) and recurrence-free survival (HR: 1.648, 95% CI: 1.060-2.563, P=0.027) in HNSCC patients.

Conclusion

TRMT12 was significantly upregulated in HNSCC tissues, which may be attributed to both genetic and epigenetic alterations. Increased TRMT12 expression may be involved in the progression and metastasis of HNSCC, and serve as an independent biomarker of poor prognosis in HNSCC with respect to overall survival and recurrence-free survival.

A nomogram based on a gene signature for predicting the prognosis of patients with head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignant tumors. The purpose of this study was to establish and validate a gene-expression-based prognostic signature in non-metastatic patients with HNSCC.

MATERIALS AND METHODS

All the patients were retrieved from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. We randomly divided the GSE65858 samples into 70% (training cohort, n = 190) and 30% (internal validation cohort, n = 72). A total of 36 samples collected from the TCGA HNSCC databases were selected as an independent external validation cohort. The oligo package in R was used to normalize the raw data before analysis. Data characteristics were extracted, and a gene signature was built via the least absolute shrinkage and selection operator regression model. The predictive model was developed by multivariable Cox regression analysis. T stage, N stage, human papilloma virus status, and the gene signature were incorporated in this predictive model, which was shown as a nomogram. Calibration and discrimination were performed to assess the performance of the nomogram. The clinical utility of this nomogram was assessed by the decision curve analysis.

RESULTS

Overall, 2001 significant messenger RNAs in HNSCC samples were identified compared with normal samples. The gene signature contained seven genes and significantly correlated with overall survival. The gene signature was also significant in subgroup analysis of the primary cohort. The calibration was plotted in the external cohort (C-index 0.90, 95% CI 0.85, 0.95) compared with the training (C-index 0.76, 95% CI 0.73, 0.79) and internal (C-index 0.71, 95% CI 0.66, 0.77) cohorts. In clinic, a decision curve analysis demonstrated that the model including the prognostic gene signature score status was better than that without it.

CONCLUSION

This study developed and validated a predictive model, which can promote the individualized prediction of overall survival in non-metastatic patients with HNSCC.

Increasing Incidence rates of Oropharyngeal Squamous Cell Carcinoma in Germany and Significance of Disease Burden Attributed to Human Papillomavirus

Increasing incidences of head and neck cancers and rising proportions of these associated with human papillomavirus (HPV), especially in the oropharynx, have been reported in international studies. So far, the trends and contribution of HPV to the number of newly diagnosed cases of oropharyngeal squamous cell carcinomas (OPSCC) in Germany are uncertain. We investigated HPV association and incidence rates in a cohort of consecutively included patients with OPSCC in Giessen 2000-2017, and compared our results with regional (Giessen and the federal state of Hesse), national (Germany), and international (United States) databases. Regional data show a significant increase in the overall incidence rates of oropharyngeal cancers and in the incidence of HPV-associated cancers of the subsites tonsils and oropharynx, whereas other oropharyngeal subsites show no significant change. Analysis of national databases shows a significant incidence increase in Germany and in the United States. The rise in incidence is predominantly attributable to male patients in the US population, whereas in Germany rising OPSCC incidence is more associated with females. There is a significant elevation of OPSCC incidence rates in Germany, which corresponds to the recognized incidence increase of HPV-related oropharyngeal cancers based on experimental data from consecutively included patients of our cohort. Our investigation shows different patterns of this increase in Germany and in the United States, which demonstrates spatial heterogeneity and the need for population-based investigations regarding the role of HPV in oropharyngeal cancer.

EpCAM ectodomain EpEX is a ligand of EGFR that counteracts EGF-mediated epithelial-mesenchymal transition through modulation of phospho-ERK1/2 in head and neck cancers

Head and neck squamous cell carcinomas (HNSCCs) are characterized by outstanding molecular heterogeneity that results in severe therapy resistance and poor clinical outcome. Inter- and intratumoral heterogeneity in epithelial-mesenchymal transition (EMT) was recently revealed as a major parameter of poor clinical outcome. Here, we addressed the expression and function of the therapeutic target epidermal growth factor receptor (EGFR) and of the major determinant of epithelial differentiation epithelial cell adhesion molecule (EpCAM) in clinical samples and in vitro models of HNSCCs. We describe improved survival of EGFR^low/EpCAM^high HNSCC patients (n = 180) and provide a molecular basis for the observed disparities in clinical outcome. EGF/EGFR have concentration-dependent dual capacities as inducers of proliferation and EMT through differential activation of the central molecular switch phosphorylated extracellular signal–regulated kinase 1/2 (pERK1/2) and EMT transcription factors (EMT-TFs) Snail, zinc finger E-box-binding homeobox 1 (Zeb1), and Slug. Furthermore, soluble ectodomain of EpCAM (EpEX) was identified as a ligand of EGFR that activates pERK1/2 and phosphorylated AKT (pAKT) and induces EGFR-dependent proliferation but represses EGF-mediated EMT, Snail, Zeb1, and Slug activation and cell migration. EMT repression by EpEX is realized through competitive modulation of pERK1/2 activation strength and inhibition of EMT-TFs, which is reflected in levels of pERK1/2 and its target Slug in clinical samples. Accordingly, high expression of pERK1/2 and/or Slug predicted poor outcome of HNSCCs. Hence, EpEX is a ligand of EGFR that induces proliferation but counteracts EMT mediated by the EGF/EGFR/pERK1/2 axis. Therefore, the emerging EGFR/EpCAM molecular cross talk represents a promising target to improve patient-tailored adjuvant treatment of HNSCCs.

Head and neck squamous cell carcinomas (HNSCCs) display poor survival, with death rates above 55%. Major factors affecting survival are metastases’ formation and therapy resistance. Phenotypic changes during partial epithelial-mesenchymal transition (EMT) provide tumor cells with increased migration, invasion, and therapy resistance. Understanding molecular mechanisms of EMT, as a central process of the metastatic cascade and the development of therapy resistance, is therefore important. In the present work, we identified molecular cross talk between epidermal growth factor receptor (EGFR) and epithelial cell adhesion molecule (EpCAM) as a novel determinant of clinical outcome in HNSCCs. Low levels of EGFR but high levels of EpCAM (EGFR^low/EpCAM^high) were associated with favorable prognosis, with survival rates above 90%, whereas EGFR^high/EpCAM^low correlated with poor survival, below 10%. EGFR was shown to have a concentration-dependent capacity to induce proliferation and EMT. Proteolytic cleavage of the extracellular domain of EpCAM (EpEX) produces a ligand of EGFR that induces EGFR-dependent proliferation but counteracts EGF-induced EMT. We delineate an EGFR/extracellular signal–regulated kinase 1/2 (ERK1/2)/EpCAM signaling axis that may be a promising therapeutic target for HNSCCs.