Adaptive ERK signalling activation in response to therapy and in silico prognostic evaluation of EGFR-MAPK in HNSCC

Deciphering the complex landscape of post-translational modifications on PKM2: Implications in head and neck cancer pathogenesis

In the vast landscape of human health, head and neck cancer (HNC) poses a significant health burden globally, necessitating the exploration of novel diagnostics and therapeutics. Metabolic alterations occurring within tumor microenvironment are crucial to understand the foundational cause of HNC. Post-translational modifications (PTMs) have recently emerged as a silent foe exerting a significantly heightened influence on various aspects of the biological processes associated with the onset and advancement of cancer, particularly in the context of HNC. There are numerous targets involved in HNC but recently, the enzyme pyruvate kinase M2 (PKM2) has come out as a hot target due to its involvement in glycolysis resulting in metabolic reprogramming of cancer cells. Various PTMs have been reported to affect the structure and function of PKM2 by modulating its activity. This review aims to investigate the impact of PTMs on the interaction between PKM2 and several signaling pathways and transcription factors in the context of HNC. These interactions possess significant ramification for cellular proliferation, apoptosis, angiogenesis and metastasis. This review primarily explores the role of PTMs influencing PKM2 and its involvement in tumor development. While acknowledging the significance of PKM2 interactions with other tumor regulators, the emphasis lies on dissecting PTM-related mechanisms rather than solely scrutinizing individual regulators. It lays the framework for the development of more sophisticated diagnostic tools and uncovers exciting possibilities for precision medicine essential for effectively addressing the complexity of this malignancy in a precise and focused manner.

Crosstalk between CAFs and tumour cells in head and neck cancer

Head and neck squamous cell carcinomas (HNSCCs) are amongst the most aggressive, complex, and heterogeneous malignancies. The standard of care treatments for HNC patients include surgery, radiotherapy, chemotherapy, or their combination. However, around 50% do not benefit while suffering severe toxic side effects, costing the individuals and society. Decades have been spent to improve HNSCC treatment outcomes with only limited success. Much of the research in HNSCC treatment has focused on understanding the genetics of the HNSCC malignant cells, but it has become clear that tumour microenvironment (TME) plays an important role in the progression as well as treatment response in HNSCC. Understanding the crosstalk between cancer cells and TME is crucial for inhibiting progression and treatment resistance. Cancer-associated fibroblasts (CAFs), the predominant component of stroma in HNSCC, serve as the primary source of extra-cellular matrix (ECM) and various pro-tumoral composites in TME. The activation of CAFs in HNSCC is primarily driven by cancer cell-secreted molecules, which in turn induce phenotypic changes, elevated secretive status, and altered ECM production profile. Concurrently, CAFs play a pivotal role in modulating the cell cycle, stemness, epithelial-mesenchymal transition (EMT), and resistance to targeted and chemoradiotherapy in HNSCC cells. This modulation occurs through interactions with secreted molecules or direct contact with the ECM or CAF. Co-culture and 3D models of tumour cells and other TME cell types allows to mimic the HNSCC tumour milieu and enable modulating tumour hypoxia and reprograming cancer stem cells (CSC). This review aims to provide an update on the development of HNSCC tumour models comprising CAFs to obtain better understanding of the interaction between CAFs and tumour cells, and for providing preclinical testing platforms of current and combination with emerging therapeutics.

N-phenyl pyrazoline derivative inhibits cell aggressiveness and enhances paclitaxel sensitivity of triple negative breast cancer cells

Protein kinase dysregulation induces cancer cell aggressiveness leading to rapid tumor progression and poor prognosis in TNBC patients. Many small-molecule kinase inhibitors have been tested in clinical trials to treat TNBC patients. In the previous study, we found that N-phenylpyrazoline small molecule acts as a protein kinase inhibitor in cervical cancer cells. However, there remains unknown about N-phenyl pyrazoline potency as a kinase inhibitor and its anti-cancer activity in TNBC cells. In this study, we investigated the activity of N-phenyl pyrazoline against TNBC cells via tyrosine kinase inhibition. Based on the MTT assay, the IC50 values for the N-phenyl pyrazoline 2, 5, A, B, C, and D against Hs578T were 12.63 µM, 3.95 µM, not available, 18.62 µM, 30.13 µM, and 26.79 µM, respectively. While only P5 exhibited the IC50 against MDA MB 231 (21.55 µM). Further, N-phenyl pyrazoline 5 treatment significantly inhibited the cell proliferation rate of Hs578T and MDA MB 231 cells. The migration assay showed that treatment with the compound N-phenyl pyrazoline 5 with 4 µM concentration significantly reduced cell migration of Hs578T cells. N-phenyl pyrazoline 5 treatment at 1 µM and 2 µM was able to reduce the tumorsphere size of Hs578t cells. A combination treatment of P5 and paclitaxel showed a synergistic effect with a combination index score > 1 in both TNBC cells. Further, the P5 predictively targeted the protein kinases that significantly correlated to breast cancer prognosis. The GSEA analysis result shows that receptor tyrosine kinase, Notch3, Notch4, and Ephrin signaling pathways were targeted by P5. The P5 treatment reduced the EGFR expression level and activation in TNBC cells.

Analysis of the effect of CCR7 on the microenvironment of mouse oral squamous cell carcinoma by single-cell RNA sequencing technology

BACKGROUND

Studies have shown that CCR7, an important inflammatory factor, can promote the proliferation and metastasis of oral squamous cell carcinoma (OSCC), but its role in the tumor microenvironment (TME) remains unclear. This paper explores the role of CCR7 in the TME of OSCC.

METHODS

In this work, we constructed CCR7 gene knockout mice and OSCC mouse models. Single-cell RNA sequencing (scRNA-seq) and bioinformatics were used to analyze the differences in the OSCC microenvironment between three CCR7 gene knockout mice (KO) and three wild-type mice (WT). Immunohistochemistry, immunofluorescence staining, and flow cytometry were used to analyze the expression of key genes in significantly different cell types between the KO and WT groups. An in vitro experiment was used to verify the effect of CCR7 on M2 macrophage polarization.

RESULTS

In the mouse OSCC models, the tumor growth rate in the KO group was significantly lower than that in the WT group. Eight main cell types (including tumor cells, fibroblasts, macrophages, granulocytes, T cells, endothelial cells, monocytes, and B cells) were identified by Seurat analysis. The scRNA-seq results showed that the proportion of tumor cells was lower, but the proportion of inflammatory cells was significantly higher in the KO group than in the WT group. CellPhoneDB analysis results indicated a strong interaction relationship between tumor cells and macrophages, T cells, fibroblasts, and endothelial cells. Functional enrichment results indicated that the expression level of the Dusp1 gene in the KO group was generally higher than that in the WT group in various cell types. Macrophage subclustering results indicated that the proportion of M2 macrophages in the KO group was lower than that in the WT group. In vitro experimental results showed that CCR7 can promote M2 macrophage polarization, thus promoting the proliferation, invasion and migration of OSCC cells.

CONCLUSIONS

CCR7 gene knockout can significantly inhibit the growth of mouse oral squamous cell carcinoma by promoting the polarization of M2 macrophages.

Cold Atmospheric Plasma Jet Irradiation Decreases the Survival and the Expression of Oncogenic miRNAs of Oral Carcinoma Cells

Despite recent advancements, therapies against advanced oral squamous cell carcinoma (OSCC) remain ineffective, resulting in unsatisfactory therapeutic outcomes. Cold atmospheric plasma (CAP) offers a promising approach in the treatment of malignant neoplasms. Although the effects of CAP in abrogating OSCC have been explored, the exact mechanisms driving CAP-induced cancer cell death and the changes in microRNA (miRNA) expression are not fully understood. We fabricated and calibrated an argon-CAP device to explore the effects of CAP irradiation on the growth and expression of oncogenic miRNAs in OSCC. The analysis revealed that, in OSCC cell lines following CAP irradiation, there was a significant reduction in viability; a downregulation of miR-21, miR-31, miR-134, miR-146a, and miR-211 expression; and an inactivation of the v-akt murine thymoma viral oncogene homolog (AKT) and extracellular signal-regulated kinase (ERK) signals. Pretreatment with blockers of apoptosis, autophagy, and ferroptosis synergistically reduced CAP-induced cell death, indicating a combined induction of variable death pathways via CAP. Combined treatments using death inhibitors and miRNA mimics, alongside the activation of AKT and ERK following the exogenous expression, counteracted the cell mortality associated with CAP. The CAP-induced downregulation of miR-21, miR-31, miR-187, and miR-211 expression was rescued through survival signaling. Additionally, CAP irradiation notably inhibited the growth of SAS OSCC cell xenografts on nude mice. The reduced expression of oncogenic miRNAs in vivo aligned with in vitro findings. In conclusion, our study provides new lines of evidence demonstrating that CAP irradiation diminishes OSCC cell viability by abrogating survival signals and oncogenic miRNA expression.

Modulation of PD‑L1 expression by standard therapy in head and neck cancer cell lines and exosomes

Although checkpoint inhibitors (CPI) have recently extended the treatment options and improved clinical response of advanced stage head and neck squamous cell carcinoma (HNSCC), treatment success remains unpredictable. Programmed cell death ligand‑1 (PD‑L1) is a key player in immunotherapy. Tumor cells, and exosomes derived therefrom, are carriers of PD‑L1 and efficiently suppress immune responses. The aim of the present study was to analyze the influence of established therapies on PD‑L1 expression of HNSCC cell lines and their exosomes. The HNSCC cell lines, UM‑SCC‑11B, UM‑SCC‑14C and UM‑SCC‑22C were treated with fractionated radiotherapy (RT; 5x2 Gy), cisplatin (CT) and cetuximab (Cetux) as monotherapy, or combined therapy, chemoradiotherapy (CRT; RT and CT) or radioimmunotherapy (RT and Cetux). The expression of PD‑L1 and phosphorylated (p)ERK1/2 as a mediator of radioresistance were assessed using western blotting, immunohistochemistry and an ex vivo vital tissue culture model. Additionally, exosomes were isolated from concentrated supernatants of the (un‑)treated HNSCC cell lines by size exclusion chromatography. Exosomal protein expression levels of PD‑L1 were detected using western blotting and semi‑quantitative levels were calculated. The functional impact of exosomes from the (un‑)treated HNSCC cell lines on the proliferation (MTS assay) and apoptosis (Caspase 3/7 assay) of the untreated HNSCC cell lines were measured and compared. The HNSCC cell lines UM‑SCC‑11B and UM‑SCC‑22B showed strong expression of pERK1/2 and PD‑L1, respectively. RT upregulated the PD‑L1 expression in UM‑SCC‑11B and UM‑SCC‑14C and in exosomes from all three cell lines. CT alone induced PD‑L1 expression in all cell lines. CRT induced the expression of PD‑L1 in all HNSCC cell lines and exosomes from UM‑SCC‑14C and UM‑SCC‑22B. The data indicated a potential co‑regulation of PD‑L1 and activated ERK1/2, most evident in UM‑SCC‑14C. Exosomes from irradiated UM‑SCC‑14C cells protected the unirradiated cells from apoptosis by Caspase 3/7 downregulation. The present study suggested a tumor cell‑mediated regulation of PD‑L1 upon platinum‑based CRT in HNSCC and in exosomes. A co‑regulation of PD‑L1 and MAPK signaling response was hypothesized.

A Novel Subgroup of UCHL1-Related Cancers Is Associated with Genomic Instability and Sensitivity to DNA-Damaging Treatment

PURPOSE

Identification of molecularly-defined cancer subgroups and targeting tumor-specific vulnerabilities have a strong potential to improve treatment response and patient outcomes but remain an unmet challenge of high clinical relevance, especially in head and neck squamous cell carcinoma (HNSC).

EXPERIMENTAL DESIGN

We established a UCHL1-related gene set to identify and molecularly characterize a UCHL1-related subgroup within TCGA-HNSC by integrative analysis of multi-omics data. An extreme gradient boosting model was trained on TCGA-HNSC based on GSVA scores for gene sets of the MSigDB to robustly predict UCHL1-related cancers in other solid tumors and cancer cell lines derived thereof. Potential vulnerabilities of UCHL1-related cancer cells were elucidated by an in-silico drug screening approach.

RESULTS

We established a 497-gene set, which stratified the TCGA-HNSC cohort into distinct subgroups with a UCHL1-related or other phenotype. UCHL1-related HNSC were characterized by higher frequencies of genomic alterations, which was also evident for UCHL1-related cancers of other solid tumors predicted by the classification model. These data indicated an impaired maintenance of genomic integrity and vulnerability for DNA-damaging treatment, which was supported by a favorable prognosis of UCHL1-related tumors after radiotherapy, and a higher sensitivity of UCHL1-related cancer cells to irradiation or DNA-damaging compounds (e.g., Oxaliplatin).

CONCLUSION

Our study established UCHL1-related cancers as a novel subgroup across most solid tumor entities with a unique molecular phenotype and DNA-damaging treatment as a specific vulnerability, which requires further proof-of-concept in pre-clinical models and future clinical trials.

Biomarkers involved in the proliferation of the odontogenic keratocyst, glandular odontogenic cyst and botryoid odontogenic cyst

INTRODUCTION

Odontogenic cysts are a heterogeneous group of lesions with varied clinical behavior.

OBJECTIVE

To analyze the expression of the epidermal growth factor receptor (EGFR), Cyclin D1, and transcription factor SOX2 in the odontogenic epithelium evaluating the cell cycle control and cystic expansion.

METHODS

This was a cross-sectional study including 40 cases, 20 odontogenic keratocysts (OKC), 10 botryoid odontogenic cysts (BOC), and 10 glandular odontogenic cysts (GOC).

RESULTS

All cases of OKC, BOC, and GOC were positive for EGFR in all layers of the cyst lining. The highest expression of nuclear Cyclin D1 was observed in the suprabasal layer of OKCs and in the basal and suprabasal layers of GOC and BOC (p < 0.001). In addition, SOX2 was only expressed in the suprabasal layer of OKCs.

CONCLUSION

The high expression of EGFR in the cyst membrane suggests that EGF stimulates epithelial proliferation in BOCs, and the high expression of SOX2 in OKCs may be related to the presence of stem cells in the lesion. Cyclin D1 is related to cell cycle disruption in G1-S contributing to stimulates epithelial proliferation of OKCs and GOCs and BOCs.

Anti-EGFR monoclonal antibody Cetuximab displays potential anti-cancer activities in feline oral squamous cell carcinoma cell lines

Feline oral squamous cell carcinoma (FOSCC) is a malignant tumor characterized by an aggressive behavior and poor prognosis, for which no fully effective therapies are available. Studies of comparative oncology suggest that epidermal growth factor receptor (EGFR) may be a therapeutic target in FOSCC, similarly to human head and neck SCC (HNSCC), where the use of anti-EGFR monoclonal antibody Cetuximab has entered the clinical practice. The aim of this study was to assess the efficacy of Cetuximab in three validated preclinical models of FOSCC (SCCF1, SCCF2, SCCF3). Sequencing of tyrosine kinase domain of EGFR in the cell lines revealed a wild-type genotype, excluding the presence of activating mutations. Western blotting experiments demonstrated that Cetuximab inhibited activation of EGFR and its downstream kinase Akt in SCCF1, SCCF2 and SCCF3 along with HNSCC cell line CAL 27 included as control. Importantly, CCK-8 and trypan blue exclusion assays revealed that treatment with Cetuximab caused a decrease in cell proliferation and cell viability in all cell lines, with a general dose- and time-dependent trend. Cell death induced by Cetuximab was associated with cleavage of PARP, indicating occurrence of apoptosis. Taken together, our data suggest that Cetuximab exerts potential anti-cancer activities in FOSCC, paving the way for future translational studies aimed at assessing its employment in the therapy of this lethal cancer of cats.

The Multiple Roles of CD147 in the Development and Progression of Oral Squamous Cell Carcinoma: An Overview

Cluster of differentiation (CD)147, also termed extracellular matrix metalloprotease inducer or basigin, is a glycoprotein ubiquitously expressed throughout the human body, the oral cavity included. CD147 actively participates in physiological tissue development or growth and has important roles in reactive processes such as inflammation, immunity, and tissue repair. It is worth noting that deregulated expression and/or activity of CD147 is observed in chronic inflammatory or degenerative diseases, as well as in neoplasms. Among the latter, oral squamous cell carcinoma (OSCC) is characterized by an upregulation of CD147 in both the neoplastic and normal cells constituting the tumor mass. Most interestingly, the expression and/or activity of CD147 gradually increase as healthy oral mucosa becomes inflamed; hyperplastic/dysplastic lesions are then set on, and, eventually, OSCC develops. Based on these findings, here we summarize published studies which evaluate whether CD147 could be employed as a marker to monitor OSCC development and progression. Moreover, we describe CD147-promoted cellular and molecular events which are relevant to oral carcinogenesis, with the aim to provide useful information for assessing whether CD147 may be the target of novel therapeutic approaches directed against OSCC.

circ_0000045 promotes proliferation, migration, and invasion of head and neck squamous cell carcinomas via regulating HSP70 and MAPK pathway

Objective

Head and neck squamous cell carcinoma (HNSCC) is one severe malignancy driven by complex cellular and signaling mechanisms. However, the roles of circular RNAs (circRNAs) in HNSCC’s development remains poorly understood. Therefore, this study investigated the functions of differentially expressed circRNAs in regulating HNSCC cell functions.

Methods

Differentially expressed circRNAs were characterized through RNA sequencing in HNSCC tissues. CircRNA’s identity was then confirmed using RT-PCR and Sanger’s sequencing. Next, expression levels of circRNA and mRNA were detected by qRT-PCR, after which protein abundances were measured by Western blotting. Subsequently, the proliferation, migration, and invasion of HNSCC cells was assessed by MTS, wound healing, and Transwell system, respectively, followed by identification of circRNA-binding proteins in HNSCC cells by circRNA pull-down, coupled with mass spectrometry.

Results

Great alterations in circRNA profiles were detected in HNSCC tissues, including the elevated expression of circ_0000045. As observed, silencing of circ_0000045 effectively repressed the proliferation, migration, and invasion of HNSCC cell lines (FaDu and SCC-9). Contrarily, circ_0000045’s overexpression promoted the proliferation, migration, and invasion in FaDu and SCC-9 cells. Results also showed that circ_0000045 was associated with multiple RNA-binding proteins in HNSCC cells, such as HSP70. Moreover, circ_0000045 knockdown enhanced HSP70 expression and inhibited JNK2 and P38’s expression in HNSCC cells, which were oppositely regulated by circ_0000045’s overexpression.

Conclusion

The high expression of circ_0000045; therefore, promoted cell proliferation, migration, and invasion during HNSCC’s development through regulating HSP70 protein and mitogen-activated protein kinase signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09880-y.

Precision drugging of the MAPK pathway in head and neck cancer

The mitogen-activating protein kinase (MAPK) pathway is central for cell proliferation, differentiation, and senescence. In human, germline defects of the pathway contribute to developmental and congenital head and neck disorders. Nearly 1/5 of head and neck squamous cell carcinoma (HNSCC) harbors MAPK pathway mutations, which are largely activating mutations. Yet, previous approaches targeting the MAPK pathway in HNSCC were futile. Most recent clinical evidences reveal remarkable, or even exceptional pharmacologic vulnerabilities of MAPK1-mutated, HRAS-mutated, KRAS-germline altered, as well as BRAF-mutated HNSCC patients with various targeted therapies, uncovering diverse opportunities for precision drugging this pathway at multiple “genetically condemned” nodes. Further, recent patient tumor omics unveil novel effects of MAPK aberrations on direct induction of CD8⁺ T cell recruitment into the HNSCC microenvironment, providing evidences for future investigation of precision immunotherapy for this large subset of patients. MAPK pathway-mutated HNSCC should warrant precision therapy assessments in vigorous manners.

HPV-Related Promoter Methylation-Based Gene Signature Predicts Clinical Prognosis of Patients With Cervical Cancer

Persistent high-risk HPV infection drives tumorigenesis in various human malignancies, including cervical, oropharyngeal, anal, and vulvar carcinomas. Although HPV-related tumors arise in several different sites, they share many common genetic and epigenetic events. Complex and heterogeneous genomic aberrations and mutations induced by high-risk HPV contribute to the initiation and progression of cervical cancer (CC). However, the associations between high-risk HPV infection and DNA methylation have not been clearly investigated. In the present study, HPV-related gene promoter methylation signature was comprehensively analyzed using multiple interactive platforms. CC patients were successfully classified into high-risk and low-risk groups with significant differences in clinical outcomes based on the HPV-related gene promoter methylation signature. Moreover, the protein levels of ALDH1A2 and clinical prognostic value were confirmed in the CC patients cohort. In summary, our study provides compelling evidence that HPV-related gene promoter methylation signature serves as a strong prognostic signature for CC patients. Clinical investigations in large CC patient cohorts are greatly needed to pave the way to implement epigenetic biomarkers into better clinical management.

Current and Emerging Molecular Therapies for Head and Neck Squamous Cell Carcinoma

Head and neck cancer affects nearly 750,000 patients, with more than 300,000 deaths annually. Advances in first line surgical treatment have improved survival rates marginally particularly in developed countries, however survival rates for aggressive locally advanced head and neck cancer are still poor. Recurrent and metastatic disease remains a significant problem for patients and the health system. As our knowledge of the genomic landscape of the head and neck cancers continues to expand, there are promising developments occurring in molecular therapies available for advanced or recalcitrant disease. The concept of precision medicine is underpinned by our ability to accurately sequence tumour samples to best understand individual patient genomic variations and to tailor targeted therapy for them based on such molecular profiling. Not only is their purported response to therapy a factor of their genomic variation, but so is their inclusion in biomarker-driven personalised medicine therapeutic trials. With the ever-expanding number of molecular druggable targets explored through advances in next generation sequencing, the number of clinical trials assessing these targets has significantly increased over recent years. Although some trials are focussed on first-line therapeutic approaches, a greater majority are focussed on locally advanced, recurrent or metastatic disease. Similarly, although single agent monotherapy has been found effective in some cases, it is the combination of drugs targeting different signalling pathways that seem to be more beneficial to patients. This paper outlines current and emerging molecular therapies for head and neck cancer, and updates readers on outcomes of the most pertinent clinical trials in this area while also summarising ongoing efforts to bring more molecular therapies into clinical practice.

Galectin‑3 blockade suppresses the growth of cetuximab‑resistant human oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a cancer associated with high mortality (accounting for 3.1/100,000 deaths per year in Brazil in 2013) and a high frequency of amplification in the expression of the epidermal growth factor receptor (EGFR). Treatment with the EGFR inhibitor cetuximab leads to drug resistance in patients with OSCC due to unknown mechanisms. Galectin‑3 (Gal‑3) is a β‑galactoside binding lectin that regulates multiple signaling pathways in cells. The present study aimed to investigate the effect of Gal‑3 in cetuximab‑resistant (cet‑R) OSCC. The OSCC HSC3 cell line was selected to establish a mouse xenograft model, which was treated with cetuximab to induce resistance. Subsequently, a Gal‑3 inhibitor was used to treat cet‑R tumors, and the tumor volume was monitored. The expression of Gal‑3, phosphorylated (p)‑ERK1/2 and p‑Akt was assessed using immunohistochemistry. The combined effect of cetuximab and the Gal‑3 inhibitor on HSC3 tumor xenografts was also investigated. HSC3 cells were cultured in vitro to investigate the regulatory effects of Gal‑3 on ERK1/2 and Akt via western blotting. In addition, the effects of the Gal‑3 inhibitor on the proliferation, colony formation, invasion and apoptosis of HSC3 cells were investigated by performing Cell Counting Kit‑8, colony formation, Transwell and apoptosis assays, respectively. In cet‑R OSCC tumors, increased expression of Gal‑3, p‑ERK1/2 and p‑Akt was observed. Further research demonstrated that Gal‑3 regulated the expression of both ERK1/2 and Akt in HSC3 cells by promoting phosphorylation. Moreover, the Gal‑3 inhibitor decreased the proliferation and invasion, but increased the apoptosis of cet‑R HSC3 cells. In addition, the Gal‑3 inhibitor suppressed the growth of cet‑R tumors. Collectively, the results indicated that the Gal‑3 inhibitor and cetuximab displayed a synergistic inhibitory effect on OSCC tumors. In summary, the present study demonstrated that Gal‑3 may serve an important role in cet‑R OSCC. The combination of cetuximab and the Gal‑3 inhibitor may display a synergistic antitumor effect, thereby inhibiting the development of cetuximab resistance in OSCC.

Molecular Pathways and Druggable Targets in Head and Neck Squamous Cell Carcinoma

Head and neck cancers are a heterogeneous group of neoplasms, affecting an ever increasing global population. Despite advances in diagnostic technology and surgical approaches to manage these conditions, survival rates have only marginally improved and this has occurred mainly in developed countries. Some improvements in survival, however, have been a result of new management and treatment approaches made possible because of our ever-increasing understanding of the molecular pathways triggered in head and neck oncogenesis, and the growing understanding of the abundant heterogeneity of this group of cancers. Some important pathways are common to other solid tumours, but their impact on reducing the burden of head and neck disease has been less than impressive. Other less known and little-explored pathways may hold the key to the development of potential druggable targets. The extensive work carried out over the last decade, mostly utilising next generation sequencing has opened up the development of many novel approaches to head and neck cancer treatment. This paper explores our current understanding of the molecular pathways of this group of tumours and outlines associated druggable targets which are deployed as therapeutic approaches in head and neck oncology with the ultimate aim of improving patient outcomes and controlling the personal and economic burden of head and neck cancer.

Targeting ERK combined with apatinib may be a promising therapeutic strategy for treating oral squamous cell carcinoma

Apatinib is an oral tyrosine kinase inhibitor that targets VEGFR2 signaling and shows potent antitumor effects in various cancers. In this study, we explored the efficacy of apatinib against oral squamous cell carcinoma (OSCC). The relationships between VEGFR2 protein expression and clinical variables were investigated in OSCC patients. OSCC tissues had higher VEGFR2 levels than paracancerous tissues. Compared to patients with low VEGFR2 expression, patients with high VEGFR2 expression had poorer overall survival (OS) and disease-free survival (DFS). Apatinib significantly induced G0/G1 phase arrest and apoptosis, inhibited cell growth and colony formation ability, and blocked autophagic flux by downregulating p-AKT and p-mTOR signaling via the VEGFR2/AKT/mTOR pathway in vitro. Moreover, the inhibition of ERK phosphorylation increased apatinib-induced apoptosis in vitro and in vivo. Apatinib synergized with SCH772984 to achieve a more significant suppression of tumor growth than individual treatment, suggesting the combination of apatinib and SCH772984 as a potent OSCC therapy.

Comparative Therapeutic Exploitability of Acute Adaptation Mechanisms to Photon and Proton Irradiation in 3D Head and Neck Squamous Cell Carcinoma Cell Cultures

For better tumor control, high-precision proton beam radiation therapy is currently being intensively discussed relative to conventional photon therapy. Here, we assumed that radiation type-specific molecular response profiles in more physiological 3D, matrix-based head and neck squamous cell carcinoma (HNSCC) cell cultures can be identified and therapeutically exploited. While proton irradiation revealed superimposable clonogenic survival and residual DNA double strand breaks (DSB) relative to photon irradiation, kinome profiles showed quantitative differences between both irradiation types. Pharmacological inhibition of a subset of radiation-induced kinases, predominantly belonging to the mitogen-activated protein kinase (MAPK) family, failed to sensitize HNSCC cells to either proton or photon irradiation. Likewise, inhibitors for ATM, DNA-PK and PARP did not discriminate between proton and photon irradiation but generally elicited a radiosensitization. Conclusively, our results suggest marginal cell line-specific differences in the radiosensitivity and DSB repair without a superiority of one radiation type over the other in 3D grown HNSCC cell cultures. Importantly, radiation-induced activity changes of cytoplasmic kinases induced during the first, acute phase of the cellular radiation response could neither be exploited for sensitization of HNSCC cells to photon nor proton irradiation.

The PI3K/Akt/mTORC signaling axis in head and neck squamous cell carcinoma: Possibilities for therapeutic interventions either as single agents or in combination with conventional therapies

The latest advances in the sequencing methods in head and neck squamous cell carcinoma (HNSCC) tissues have revolutionized our understanding of the disease by taking off the veil from the most frequent genetic alterations in the components of the oncogenic pathways. Among all the identified alterations, aberrancies in the genes attributed to the phosphoinositide 3-kinases (PI3K) axis have attracted special attention as they were altered in more than 90% of the tissues isolated from HNSCC patients. In fact, the association between these aberrancies and the increased risk of cancer metastasis suggested this axis as an "Achilles Heel" of HNSCC, which may be therapeutically targeted. The results of the clinical trials investigating the therapeutic potential of the inhibitors targeting the components of the PI3K axis in the treatment of HNSCC patients, either alone or in a combined-modal strategy, opened a new chapter in the treatment strategy of this malignancy. The present study aimed to review the importance of the PI3K axis in the pathogenesis of HNSCC and also provide a piece of information about the breakthroughs and challenges of PI3K inhibitors in the therapeutic strategies of the disease.

Mitogen-activated protein kinase inhibition-induced modulation of epidermal growth factor receptor signaling in human head and neck squamous cell carcinoma

BACKGROUND

Epidermal growth factor receptor (EGFR) overexpression is one of the most notable characteristics in head and neck squamous cell carcinoma (HNSCC). The MAPK kinase (MEK) inhibitor trametinib has shown efficacy to treat HNSCC; however, the molecular mechanism remains unclear.

METHODS

HNSCC lines, mouse models, Western blot, and flow cytometry were employed to analyze the anticancer effects of trametinib.

RESULTS

The JHU-011, JHU-022, and JHU-029 HNSCC cells with different genetic alterations were highly susceptible to trametinib. Trametinib effectively reduced EGFR expression, which was accompanied by the reduction of pro-survival protein MYC, and the increased expression of a MYC-targeted cyclin-dependent kinase inhibitor p27kip1 and pro-apoptotic protein BIM. Trametinib resulted in G1 arrest of the cells, markedly reduced cell numbers in S phase, and significantly increased apoptosis. In mouse models, trametinib strongly inhibited tumors growth.

CONCLUSIONS

The MAPK-ERK signaling inhibition by trametinib may target EGFR and the downstream proteins against HNSCC.