The potential role of YAP in head and neck squamous cell carcinoma

Effect of deubiquitinases in head and neck squamous cell carcinoma (Review)

HNSCC includes nasopharyngeal, laryngeal and oral cancers, and its pathogenesis is influenced by various factors. As an essential part of the ubiquitin (Ub)-proteasome system (UPS), deubiquitinating enzymes (DUBs) maintain the homeostasis of Ub molecules and influence the physiological functions of cells and disease processes by removing ubiquitinated proteins. Accumulating evidence has confirmed that the aberrant expression of DUBs is involved in cell proliferation, metastasis, and apoptosis during the development of HNSCC, with some acting as oncogenes and others as tumor-suppressor genes. In this review, the DUBs implicated in HNSCC were summarized and the mechanisms underlying abnormal DUBs expression in signaling pathways were discussed. In addition, given the important role of DUBs in tumorigenesis, recent studies were reviewed and agonists and inhibitors of DUBs were summarized to identify more effective therapeutic strategies.

CTSG restraines the proliferation and metastasis of head and neck squamous cell carcinoma by blocking the JAK2/STAT3 pathway

BACKGROUND

Head and neck squamous cell carcinoma (HNSC) is recognized as the sixth most prevalent cancer globally, with around 900,000 new cases diagnosed each year. The management of HNSC poses significant challenges due to its rising incidence and suboptimal treatment outcomes in many patients. Thus, understanding the underlying molecular mechanisms that drive the onset and advancement of HNSC is crucial in order to steer the creation of novel treatment strategies. Previous researches have suggested that Cathepsin G (CTSG), a serine protease, may play a role in tumorigenesis, but its exact function in HNSC is still unknown.

METHODS

The TCGA and GTEx datasets were utilized to examine the expression and potential role of CTSG in pancancer. CTSG expression in HNSC tissues and normal tissues was analyzed using qRT-PCR, Western blot and immunohistochemistry techniques. The effects of altering CTSG expression on proliferation, migration, and apoptosis of HNSC cells were evaluated using various tests such as MTT assays, colony formation assays, wound-healing assays, transwell assays, flow cytometry, and xenograft tumor growth models. The functionality of CTSG on the JAK2/STAT3 pathway was validated using activators and inhibitors of this pathway after comfirming that CTSG could regulate this pathway.

RESULTS

In our study, we indicated that CTSG expression in HNSC tumor tissues was significantly lower than in adjacent normal tissues and CTSG gene level was positively correlated with patient prognosis. Additionally, we observed a decrease in tumor proliferation and migration, as well as an increase in apoptosis, following CTSG overexpression. Conversely, opposite effects were noted upon CTSG knockdown. Mechanistically, CTSG overexpression inhibited JAK2/STAT3 signaling, while CTSG knockdown activated it. This was confirmed by using IL-6 and JAK2 inhibitor.

CONCLUSION

CTSG impedes the proliferation and metastasis of HNSC in vivo and in vitro. CTSG is potential to act as a cancer suppressor in HNSC by focusing on the JAK2/STAT3 signaling pathway, indicating its possible use as a diagnostic marker and treatment target for HNSC.

Targeted CRISPR/Cas9 Lipid Nanoparticles Elicits Therapeutic Genome Editing in Head and Neck Cancer

Squamous cell carcinomas of the head and neck (HNSCC) originate in the upper aerodigestive tract, including the oral cavity, pharynx, and larynx. Current treatments of locally advanced HNSCC often lead to high treatment failure, and disease recurrence, resulting in poor survival rates. Advances in mRNA technologies and lipid nanoparticle (LNP) delivery systems led to several clinical trials involving LNP-CRISPR-Cas9 mRNA-based therapeutics. Despite these advances, achieving cell-type-specific extrahepatic mRNA delivery is still challenging. This study introduces a safe and effective intratumoral EGFR-targeted CRISPR-LNP delivery strategy for knocking out SOX2, which is a cancer-specific gene. To assess their therapeutic potential, it is shown that LNPs made from ionizable lipids with helper lipids co-encapsulating Cas9 mRNA and sgRNA targeting SOX2 (sgSOX2), lead to a ≈60% reduction in HNSCC cell viability in vitro. Next, using a xenograft HNSCC mouse model, targeted delivery of 𝜶EGFR- CRISPR-sgSOX2-LNPs to HNSCC cells resulted in a 90% inhibition of tumor growth and a 90% increase in survival for > 84 days, with tumor disappearance observed in 50% of the mice. These findings emphasize the potential of targeted mRNA-Cas9-LNPs in clinically accessible solid tumors, specifically in reaching tumor cells and inducing persistent therapeutic responses in tumors with high-recurrence rates like HNSCC.

A novel m6A reader RBFOX2 expression is increased in oral squamous cell carcinoma and promotes tumorigenesis

BACKGROUND AND OBJECTIVE

Oral squamous cell carcinoma (OSCC) is a significant global health concern due to its aggressive nature and poor prognosis. Recent research has highlighted the important role of RNA modifications in cancer biology, especially N6-methyladenosine (m6A) modifications, which are controlled by a complex interplay of m6A regulators. This study specifically investigates RBFOX2, a new m6A reader, and its involvement in OSCC.

METHODS

Our study primarily utilized OSCC tissue, adjacent normal tissue samples, OSCC cell lines, and normal healthy oral keratinocytes to validate RBFOX2 mRNA expression. Additionally, we used the TCGA-HNSCC dataset for large cohort analysis and clinicopathological characterization. Furthermore, we visualized the RBFOX2 network to identify the primary functions of the protein.

RESULTS

Our research shows a noticeable increase in RBFOX2 expression in OSCC tissues compared to adjacent non-tumorous tissues, as determined by quantitative PCR and immunohistochemistry analyses. Functional pathway enrichment analysis revealed that RBFOX2 is involved in the receptor tyrosine kinase signaling pathway and the Hippo signaling pathway, which plays a critical role in oral cancer development and progression. Clinically, elevated RBFOX2 expression correlated with advanced tumor stages and poorer patient outcomes, demonstrating its prognostic value. These findings indicate that RBFOX2 acts as an oncogenic driver in OSCC as an m6A reader, facilitating the expression of m6A-modified oncogenes.

CONCLUSION

Our study identifies RBFOX2 as a critical player in OSCC pathogenesis and opens avenues for novel therapeutic strategies targeting the m6A regulatory machinery in this malignancy.

Single-nucleus CUT&RUN elucidates the function of intrinsic and genomics-driven epigenetic heterogeneity in head and neck cancer progression

Interrogating regulatory epigenetic alterations during tumor progression at the resolution of single cells has remained an understudied area of research. Here we developed a highly sensitive single-nucleus CUT&RUN (snCUT&RUN) assay to profile histone modifications in isogenic primary, metastatic, and cisplatin-resistant head and neck squamous cell carcinoma (HNSCC) patient-derived tumor cell lines. We find that the epigenome can be involved in diverse modes to contribute toward HNSCC progression. First, we demonstrate that gene expression changes during HNSCC progression can be comodulated by alterations in both copy number and chromatin activity, driving epigenetic rewiring of cell states. Furthermore, intratumor epigenetic heterogeneity (ITeH) may predispose subclonal populations within the primary tumor to adapt to selective pressures and foster the acquisition of malignant characteristics. In conclusion, snCUT&RUN serves as a valuable addition to the existing toolkit of single-cell epigenomic assays and can be used to dissect the functionality of the epigenome during cancer progression.

YAP-driven malignant reprogramming of oral epithelial stem cells at single cell resolution

Tumor initiation represents the first step in tumorigenesis during which normal progenitor cells undergo cell fate transition to cancer. Capturing this process as it occurs in vivo, however, remains elusive. Here we employ spatiotemporally controlled oncogene activation and tumor suppressor inhibition together with multiomics to unveil the processes underlying oral epithelial progenitor cell reprogramming into tumor initiating cells at single cell resolution. Tumor initiating cells displayed a distinct stem-like state, defined by aberrant proliferative, hypoxic, squamous differentiation, and partial epithelial to mesenchymal invasive gene programs. YAP-mediated tumor initiating cell programs included activation of oncogenic transcriptional networks and mTOR signaling, and recruitment of myeloid cells to the invasive front contributing to tumor infiltration. Tumor initiating cell transcriptional programs are conserved in human head and neck cancer and associated with poor patient survival. These findings illuminate processes underlying cancer initiation at single cell resolution, and identify candidate targets for early cancer detection and prevention.

The interplay between microbiome and host factors in pathogenesis and therapy of head and neck cancer

Heterogeneous cancers that lack strong driver mutations with high penetrance, such as head and neck squamous cell carcinoma (HNSCC), present unique challenges to understanding their aetiology due to the complex interactions between genetics and environmental factors. The interplay between lifestyle factors (such as poor oral hygiene, smoking, or alcohol consumption), the oral and gut microbiome, and host genetics appears particularly important in the context of HNSCC. The complex interplay between the gut microbiota and cancer treatment outcomes has also received increasing attention in recent years. This review article describes the bidirectional communication between the host and the oral/gut microbiome, focusing on microbiome-derived metabolites and their impact on systemic immune responses and the modulation of the tumour microenvironment. In addition, we review the role of host lifestyle factors in shaping the composition of the oral/gut microbiota and its impact on cancer progression and therapy. Overall, this review highlights the rationality of considering the oral/gut microbiota as a critical determinant of cancer therapy outcomes and points to therapeutic opportunities offered by targeting the oral/gut microbiota in the management of HNSCC.

Circ_0002722-induced regulation of YAP promotes platinum resistance in oral squamous cell carcinoma: Implications for verteporfin therapy

Oral squamous cell carcinoma (OSCC) poses a significant public health burden due to its high prevalence and poor prognosis. Platinum resistance is one of the major challenges in OSCC treatment. Yes-associated protein (YAP) has been identified as a pivotal player in OSCC tumorigenesis and progression. Circular RNA (circRNA) has been implicated in chemoresistance in various cancers by regulation the function of microRNA. Nevertheless, the specific mechanisms linking circRNA to YAP expression in OSCC remain poorly understood. In this study, we detected the YAP and circRNA hsa_circ_0002722 (circ_0002722) expression by western blot (WB) and quantitative polymerase chain reaction (qPCR). We found that YAP and circ_0002722 were up-regulated in platinum resistance in OSCC tissues. Furthermore, transfection of circ_0002722 siRNA into platinum-resistant cells revealed that circ_0002722 acted as a regulator of miR-1305, which influenced YAP expression and thereby affected platinum sensitivity. In vivo experiments corroborated the synergistic effects of cisplatin and verteporfin (a YAP inhibitor) in combating platinum resistance. Targeting YAP emerges as a promising therapeutic strategy for addressing platinum resistance in OSCC, with circ_0002722 serving as a potential therapy target and valuable diagnostic marker. These findings shed light on the underlying mechanisms of platinum resistance, paving the way for the development of effective treatment approaches.

Exploring the Relationship Between YAP (Yes-Associated Protein) and VEGF-A with Distant Metastasis in Nasopharyngeal Carcinoma

OBJECTIVE

To investigate the relationship between Yes-Associated Protein (YAP) and Vascular Endothelial Growth Factor-A (VEGF-A) in nasopharyngeal carcinoma (NPC) and evaluate their potential as predictive biomarkers for distant metastasis.

METHODS

This observational analytic study was conducted from May to August 2023, including 60 NPC cases diagnosed histopathologically at the Department of Anatomical Pathology, Faculty of Medicine, Universitas Indonesia/Cipto Mangunkusumo Hospital. The study involved 30 NPC cases with distant metastasis and 30 without distant metastasis. Immunohistochemical analysis was performed using primary antibodies (rabbit YAP, D8H1X; mouse VEGF, clone C-1 sc-7269). Expression levels of YAP and VEGF-A were semi-quantitatively assessed using the H-score formula on 500 tumor cells. Cutoff points for YAP and VEGF-A were determined through Receiver Operating Characteristic (ROC) curve analysis and the Youden index. Statistical analyses, including Chi-square tests, were conducted using SPSS 25.0 to evaluate the relationship between marker expression and the presence of distant metastasis.

RESULTS

A significant difference in YAP expression was observed between NPC cases with distant metastasis (80%) and those without (23.3%, p<0.001). Similarly, VEGF-A expression was notably higher in cases with distant metastasis (86.7%) compared to those without (20%, p<0.001). A significant association between YAP and VEGF-A expression was found (p=0.001). ROC curve analysis showed that YAP (AUC=0.738, 95% CI 0.602-0.874) and VEGF-A (AUC=0.842, 95% CI 0.735-0.950) effectively predict distant metastasis. The double co-high-expression group (elevated YAP and VEGF-A) exhibited a significantly higher rate of distant metastasis compared to the non-double co-high-expression group (p<0.001).

CONCLUSION

Elevated expressions of YAP and VEGF-A are significantly associated with distant metastasis in NPC, suggesting their potential as biomarkers for predicting metastatic risk.

Gene-Expression Patterns of Tumor and Peritumor Tissues of Smoking and Non-Smoking HPV-Negative Patients with Head and Neck Squamous Cell Carcinoma

We studied the gene-expression patterns in specimens of tumor and peritumor tissue biopsies of 26 patients with head and neck carcinomas depending on smoking status. Histological and immunohistochemical examinations verified that all tumors belonged to the "classical" subgroup of head and neck carcinomas, and the HPV-negative tumor status was confirmed. The expression of 28 tumor-associated genes determined by RT-PCR was independent of patients' sex or age, TNM status, degree of differentiation, or tissue localization. Moreover, in peritumor tissue, none of the 28 genes were differentially expressed between the groups of smoking and nonsmoking patients. During oncotransformation in both studied groups, there were similar processes typical for HNSCC progression: the expression levels of paired keratins 4 and 13 were reduced, while the expression levels of keratin 17 and CD44 were significantly increased. However, further investigation revealed some distinctive features: the expression of the genes EGFR and TP63 increased significantly only in the nonsmoking group, and the expression of IL6, CDKN2A, EGF, and PITX1 genes changed only in the smoking group. In addition, correlation analysis identified several clusters within which genes displayed correlations in their expression levels. The largest group included 10 genes: TIMP1, TIMP2, WEE1, YAP, HIF1A, PI3KCA, UTP14A, APIP, PTEN, and SLC26A6. The genetic signatures associated with smoking habits that we have found may serve as a prerequisite for the development of diagnostic panels/tests predicting responses to different therapeutic strategies for HNSCC.

scGIST: gene panel design for spatial transcriptomics with prioritized gene sets

A critical challenge of single-cell spatial transcriptomics (sc-ST) technologies is their panel size. Being based on fluorescence in situ hybridization, they are typically limited to panels of about a thousand genes. This constrains researchers to build panels from only the marker genes of different cell types and forgo other genes of interest, e.g., genes encoding ligand-receptor complexes or those in specific pathways. We propose scGIST, a constrained feature selection tool that designs sc-ST panels prioritizing user-specified genes without compromising cell type detection accuracy. We demonstrate scGIST's efficacy in diverse use cases, highlighting it as a valuable addition to sc-ST's algorithmic toolbox.

The mechanisms of action of metformin on head and neck cancer in the pre-clinical setting: a scoping review

This scoping review identifies the mechanistic pathways of metformin when used to treat head and neck cancer cells, in the pre-clinical setting. Understanding the underlying mechanisms will inform future experimental designs exploring metformin as a potential adjuvant for head and neck cancer. This scoping review was conducted according to the Joanna-Briggs Institute framework. A structured search identified 1288 studies, of which 52 studies fulfilled the eligibility screen. The studies are presented in themes addressing hallmarks of cancer. Most of the studies demonstrated encouraging anti-proliferative effects in vitro and reduced tumor weight and volume in animal models. However, a few studies have cautioned the use of metformin which supported cancer cell growth under certain conditions.

The significance of Hippo pathway protein expression in oral squamous cell carcinoma

Introduction

The Hippo pathway consists of mammalian sterile 20-like kinase 1/2 (MST1/2), large tumor suppressor 1/2 (LATS1/2), and yes-associated protein (YAP)1. Herein, we present the first report on the significance of major Hippo pathway protein expression in oral squamous cell carcinoma (OSCC).

Methods

The analyses included oral epithelial dysplasia (OED, n = 7), carcinoma in situ (CIS, n = 14), and oral squamous cell carcinoma (OSCC, n = 109).

Results

Cytoplasmic expression of MST1, LATS1, and LATS2 was low in OED, CIS, and OSCC. The cytoplasmic expression of MST2 was high in OED (5/7 cases), CIS (9/14 cases), and poorly differentiated OSCC (8/8 cases) but was low/lost in a proportion of differentiated OSCC (60/101 cases). The expression of YAP1 was associated with differentiation; low YAP expression was significantly more frequent in well-differentiated OSCC (35/71 cases), compared to moderately and poorly differentiated OSCC (11/38 cases). An infiltrative invasion pattern was associated with a high expression of MST2 and high expression of YAP1. The high expression of YAP1 was associated with features of epithelial-to-mesenchymal transition (EMT), such as the loss of E-cadherin and high expression of vimentin, laminin 5, and Slug. High expression of protein arginine methyltransferase (PRMT) 1 or 5, which positively regulates YAP activity, was associated with the high expression of YAP1 (p < 0.0001).

Conclusion

Among the major Hippo pathway proteins, MST2 displayed a distinctive expression pattern in a significant proportion of differentiated OSCC, suggesting a possible differential role for MST2 depending on the course of OSCC progression. A high YAP1 expression may indicate aggressive OSCC with EMT via PRMTs at the invasive front.

TM4SF19 controls GABP-dependent YAP transcription in head and neck cancer under oxidative stress conditions

Tobacco and alcohol are risk factors for human papillomavirus-negative head and neck squamous cell carcinoma (HPV- HNSCC), which arises from the mucosal epithelium of the upper aerodigestive tract. Notably, despite the mutagenic potential of smoking, HPV- HNSCC exhibits a low mutational load directly attributed to smoking, which implies an undefined role of smoking in HPV- HNSCC. Elevated YAP (Yes-associated protein) mRNA is prevalent in HPV- HNSCC, irrespective of the YAP gene amplification status, and the mechanism behind this upregulation remains elusive. Here, we report that oxidative stress, induced by major risk factors for HPV- HNSCC such as tobacco and alcohol, promotes YAP transcription via TM4SF19 (transmembrane 4 L six family member 19). TM4SF19 modulates YAP transcription by interacting with the GABP (Guanine and adenine-binding protein) transcription factor complex. Mechanistically, oxidative stress induces TM4SF19 dimerization and topology inversion in the endoplasmic reticulum membrane, which in turn protects the GABPβ1 subunit from proteasomal degradation. Conversely, depletion of TM4SF19 impairs the survival, proliferation, and migration of HPV- HNSCC cells, highlighting the potential therapeutic relevance of targeting TM4SF19. Our findings reveal the roles of the key risk factors of HPV- HNSCC in tumor development via oxidative stress, offering implications for upcoming therapeutic approaches in HPV- HNSCC.

Involvement of the OTUB1-YAP1 axis in driving malignant behaviors of head and neck squamous cell carcinoma

BACKGROUND

Comprehending the molecular mechanisms underlying head and neck squamous cell carcinoma (HNSCC) is vital for the development of effective treatment strategies. Deubiquitinating enzymes (DUBs), which regulate ubiquitin-dependent pathways, are potential targets for cancer therapy because of their structural advantages. Here we aimed to identify a potential target for HNSCC treatment among DUBs.

METHODS

A screening process was conducted using RNA sequencing data and clinical information from HNSCC patients in the TCGA database. A panel of 88 DUBs was analyzed to identify those associated with poor prognosis. Subsequently, HNSCC cells were modified to overexpress specific DUBs, and their effects on cell proliferation and invasion were evaluated. In vivo experiments were performed to validate the findings.

RESULTS

In HNSCC patients, USP10, USP14, OTUB1, and STAMBP among the screened DUBs were associated with a poor prognosis. Among them, OTUB1 showed the most aggressive characteristics in both in vitro and in vivo experiments. Additionally, OTUB1 regulated the stability and nuclear localization of YAP1, a substrate involved in cell proliferation and invasion. Notably, OTUB1 expression exhibited a positive correlation with the HNSCC-YAP score in HNSCC cells.

CONCLUSIONS

This study highlights the critical role of OTUB1 in HNSCC progression via modulating YAP1. Targeting the OTUB1-YAP1 axis holds promise as a potential therapeutic strategy for HNSCC treatment.

Targeted therapy for head and neck cancer: signaling pathways and clinical studies

Head and neck cancer (HNC) is malignant, genetically complex and difficult to treat and is the sixth most frequent cancer, with tobacco, alcohol and human papillomavirus being major risk factors. Based on epigenetic data, HNC is remarkably heterogeneous, and treatment remains challenging. There is a lack of significant improvement in survival and quality of life in patients with HNC. Over half of HNC patients experience locoregional recurrence or distal metastasis despite the current multiple traditional therapeutic strategies and immunotherapy. In addition, resistance to chemotherapy, radiotherapy and some targeted therapies is common. Therefore, it is urgent to explore more effective and tolerable targeted therapies to improve the clinical outcomes of HNC patients. Recent targeted therapy studies have focused on identifying promising biomarkers and developing more effective targeted therapies. A well understanding of the pathogenesis of HNC contributes to learning more about its inner association, which provides novel insight into the development of small molecule inhibitors. In this review, we summarized the vital signaling pathways and discussed the current potential therapeutic targets against critical molecules in HNC, as well as presenting preclinical animal models and ongoing or completed clinical studies about targeted therapy, which may contribute to a more favorable prognosis of HNC. Targeted therapy in combination with other therapies and its limitations were also discussed.

The Role of Deubiquitinating Enzyme in Head and Neck Squamous Cell Carcinoma

Ubiquitination and deubiquitination are two popular ways for the post-translational modification of proteins. These two modifications affect intracellular localization, stability, and function of target proteins. The process of deubiquitination is involved in histone modification, cell cycle regulation, cell differentiation, apoptosis, endocytosis, autophagy, and DNA repair after damage. Moreover, it is involved in the processes of carcinogenesis and cancer development. In this review, we discuss these issues in understanding deubiquitinating enzyme (DUB) function in head and neck squamous cell carcinoma (HNSCC), and their potential therapeutic strategies for HNSCC patients are also discussed.

Fluid Biomarkers in HPV and Non-HPV Related Oropharyngeal Carcinomas: From Diagnosis and Monitoring to Prognostication-A Systematic Review

Biomarkers are crucial in oncology, from detection and monitoring to guiding management and predicting treatment outcomes. Histological assessment of tissue biopsies is currently the gold standard for oropharyngeal cancers, but is technically demanding, invasive, and expensive. This systematic review aims to review current markers that are detectable in biofluids, which offer promising non-invasive alternatives in oropharyngeal carcinomas (OPCs). A total of 174 clinical trials from the PubMed search engine in the last 5 years were identified and screened by 4 independent reviewers. From these, 38 eligible clinical trials were found and subsequently reviewed. The biomarkers involved, categorized by human papillomavirus (HPV)-status, were further divided according to molecular and cellular levels. Recent trials investigating biomarkers for both HPV-positive and HPV-negative OPCs have approaches from various levels and different biofluids including plasma, oropharyngeal swabs, and oral rinse. Promising candidates have been found to aid in detection, staging, and predicting prognosis, in addition to well-established factors including HPV-status, drinking and smoking status. These studies also emphasize the possibility of enhancing prediction results and increasing statistical significance by multivariate analyses. Liquid biopsies offer promising assistance in enhancing personalized medicine for cancer treatment, from lowering barriers towards early screening, to facilitating de-escalation of treatment. However, further research is needed, and the combination of liquid biopsies with pre-existing methods, including in vivo imaging and invasive techniques such as neck dissections, could also be explored in future trials.

Integrating Genetic Alterations and the Hippo Pathway in Head and Neck Squamous Cell Carcinoma for Future Precision Medicine

Genetic alterations and dysregulation of signaling pathways are indispensable for the initiation and progression of cancer. Understanding the genetic, molecular, and signaling diversities in cancer patients has driven a dynamic change in cancer therapy. Patients can select a suitable molecularly targeted therapy or immune checkpoint inhibitor based on the driver gene alterations determined by sequencing of cancer tissue. This “precision medicine” approach requires detailed elucidation of the mechanisms connecting genetic alterations of driver genes and aberrant downstream signaling pathways. The regulatory mechanisms of the Hippo pathway and Yes-associated protein/transcriptional co-activator with PDZ binding motif (YAP/TAZ) that have central roles in cancer cell proliferation are not fully understood, reflecting their recent discovery. Nevertheless, emerging evidence has shown that various genetic alterations dysregulate the Hippo pathway and hyperactivate YAP/TAZ in cancers, including head and neck squamous cell carcinoma (HNSCC). Here, we summarize the latest evidence linking genetic alterations and the Hippo pathway in HNSCC, with the aim of contributing to the continued development of precision medicine.

Mechanisms of Cisplatin Resistance in HPV Negative Head and Neck Squamous Cell Carcinomas

Head and neck squamous cell carcinomas (HNSCCs) are the eighth most common cancers worldwide. While promising new therapies are emerging, cisplatin-based chemotherapy remains the gold standard for advanced HNSCCs, although most of the patients relapse due to the development of resistance. This review aims to condense the different mechanisms involved in the development of cisplatin resistance in HNSCCs and highlight future perspectives intended to overcome its related complications. Classical resistance mechanisms include drug import and export, DNA repair and oxidative stress control. Emerging research identified the prevalence of these mechanisms in populations of cancer stem cells (CSC), which are the cells mainly contributing to cisplatin resistance. The use of old and new CSC markers has enabled the identification of the characteristics within HNSCC CSCs predisposing them to treatment resistance, such as cell quiescence, increased self-renewal capacity, low reactive oxygen species levels or the acquisition of epithelial to mesenchymal transcriptional programs. In the present review, we will discuss how cell intrinsic and extrinsic cues alter the phenotype of CSCs and how they influence resistance to cisplatin treatment. In addition, we will assess how the stromal composition and the tumor microenvironment affect drug resistance and the acquisition of CSCs' characteristics through a complex interplay between extracellular matrix content as well as immune and non-immune cell characteristics. Finally, we will describe how alterations in epigenetic modifiers or other signaling pathways can alter tumor behavior and cell plasticity to induce chemotherapy resistance. The data generated in recent years open up a wide range of promising strategies to optimize cisplatin therapy, with the potential to personalize HNSCC patient treatment strategies.

CD44 promotes hepatocellular carcinoma progression via upregulation of YAP

Hepatocellular carcinoma (HCC) is a common malignancy in human. CD44 is a transmembrane glycoprotein which is frequently overexpressed in cancer of various origins. The function and mechanism of CD44 in HCC remains elusive. In this study, we reported that CD44 was overexpressed in HCC to promote the proliferation and migration of HCC cells via oncogenic YAP, which is the key downstream regulator in Hippo pathway. These findings suggest that CD44-YAP is a probable important axis in pathogenesis of HCC, providing an insight in to HCC pathogenesis as well as potential targets for the intervention of HCC.

Precision Medicine Gains Momentum: Novel 3D Models and Stem Cell-Based Approaches in Head and Neck Cancer

Despite the current progress in the development of new concepts of precision medicine for head and neck squamous cell carcinoma (HNSCC), in particular targeted therapies and immune checkpoint inhibition (CPI), overall survival rates have not improved during the last decades. This is, on the one hand, caused by the fact that a significant number of patients presents with late stage disease at the time of diagnosis, on the other hand HNSCC frequently develop therapeutic resistance. Distinct intratumoral and intertumoral heterogeneity is one of the strongest features in HNSCC and has hindered both the identification of specific biomarkers and the establishment of targeted therapies for this disease so far. To date, there is a paucity of reliable preclinical models, particularly those that can predict responses to immune CPI, as these models require an intact tumor microenvironment (TME). The "ideal" preclinical cancer model is supposed to take both the TME as well as tumor heterogeneity into account. Although HNSCC patients are frequently studied in clinical trials, there is a lack of reliable prognostic biomarkers allowing a better stratification of individuals who might benefit from new concepts of targeted or immunotherapeutic strategies. Emerging evidence indicates that cancer stem cells (CSCs) are highly tumorigenic. Through the process of stemness, epithelial cells acquire an invasive phenotype contributing to metastasis and recurrence. Specific markers for CSC such as CD133 and CD44 expression and ALDH activity help to identify CSC in HNSCC. For the majority of patients, allocation of treatment regimens is simply based on histological diagnosis and on tumor location and disease staging (clinical risk assessments) rather than on specific or individual tumor biology. Hence there is an urgent need for tools to stratify HNSCC patients and pave the way for personalized therapeutic options. This work reviews the current literature on novel approaches in implementing three-dimensional (3D) HNSCC in vitro and in vivo tumor models in the clinical daily routine. Stem-cell based assays will be particularly discussed. Those models are highly anticipated to serve as a preclinical prediction platform for the evaluation of stable biomarkers and for therapeutic efficacy testing.