Shooting at Moving and Hidden Targets-Tumour Cell Plasticity and the Notch Signalling Pathway in Head and Neck Squamous Cell Carcinomas

Annexin A1 Is Involved in the Antitumor Effects of 5-Azacytidine in Human Oral Squamous Carcinoma Cells

Background: the treatment of squamous cell carcinomas of the oral cavity (OSCCs) is limited by the lack of reliable diagnostic/prognostic, and predictive markers, as well as by intrinsic tumor cell heterogeneity. 5-azacytidine (5-AZA) offers opportunities for cancer cell reprogramming to develop new target-specific treatments. The protein annexin A1 (ANXA1) is downregulated in head and neck squamous cell carcinoma (HNSCC), correlated with pathological differentiation grade. Objectives: this work aimed to further investigate the role of ANXA1 in OSCC progression based on 5-AZA activity. Methods: we used CAL27 and CAL33 cell lines, which differ in drug sensitivity and differentiation status. Results: CAL27 showed a higher expression of the stemness markers compared to CAL33 cells, but this positivity was lost after treatment with 5-AZA. This drug also decreased CAL27 cell motility, promoting a less aggressive phenotype. Moreover, 5-AZA increased ANXA1 expression only in CAL27. After siRNA-mediated downmodulation, we witnessed a significant rise in cell motility and the inversion of E-/N-cadherin expression, which was reverted again by 5-AZA. To investigate the role of exogenous ANXA1 derived from the tumor microenvironment, we treated CAL27 with Ac2-26, an ANXA1 mimetic peptide. Interestingly, we found that this peptide alone showed impacts similar to 5-AZA in reversing the aggressive phenotype. All these effects were not evidenced in CAL33 cells. Finally, to prove the loop of the exogenous protein, we detected increased expression of its receptors, formyl peptide receptors (FPRs), and their activation, leading to oncosuppressor effects. Conclusions: we propose that ANXA1 mediates the effects of 5-AZA only in poorly differentiated stemlike CAL27 cell lines. This suggests the relevance of ANXA1 as a diagnostic/prognostic biomarker in OSCCs, paving the way for personalized therapies to overcome treatment difficulties.

Discovery of paradoxical genes: reevaluating the prognostic impact of overexpressed genes in cancer

Oncogenes are typically overexpressed in tumor tissues and often linked to poor prognosis. However, recent advancements in bioinformatics have revealed that many highly expressed genes in tumors are associated with better patient outcomes. These genes, which act as tumor suppressors, are referred to as "paradoxical genes." Analyzing The Cancer Genome Atlas (TCGA) confirmed the widespread presence of paradoxical genes, and KEGG analysis revealed their role in regulating tumor metabolism. Mechanistically, discrepancies between gene and protein expression-affected by pre- and post-transcriptional modifications-may drive this phenomenon. Mechanisms like upstream open reading frames and alternative splicing contribute to these inconsistencies. Many paradoxical genes modulate the tumor immune microenvironment, exerting tumor-suppressive effects. Further analysis shows that the stage- and tumor-specific expression of these genes, along with their environmental sensitivity, influence their dual roles in various signaling pathways. These findings highlight the importance of paradoxical genes in resisting tumor progression and maintaining cellular homeostasis, offering new avenues for targeted cancer therapy.

Chaperonin containing TCP1 subunit 6A may activate Notch and Wnt pathways to facilitate the malignant behaviors and cancer stemness in oral squamous cell carcinoma

Chaperonin containing TCP1 subunit 6A (CCT6A) was recently discovered to be involved in cancer pathogenesis and stemness; however, its role in oral squamous cell carcinoma (OSCC) has not been reported. The current study aimed to investigate the impact of CCT6A on OSCC cell malignant behaviors and stemness and to explore its potentially interreacted pathways. SCC-15 and HSC-3 cells were transfected with the plasmid loading control overexpression, CCT6A overexpression, control knockout, or CCT6A knockout. Wnt4 overexpression or Notch1 overexpression plasmids were transfected into CCT6A-knockout SCC-15 cells. Cell proliferation, apoptosis, invasion, stemness, Notch, and Wnt pathways were detected in both cell lines, whereas RNA sequencing was only performed in SCC-15 cells. CCT6A was upregulated in five OSCC cell lines, including SCC-15, HSC-3, SAT, SCC-9, and KON, compared to that in the control cell line. In SCC-15 and HSC-3 cells, CCT6A overexpression increased cell proliferation, invasion, sphere formation, CD133, and Sox2 expression, but decreased cell apoptosis; on the contrary, CCT6A knockout exhibited an opposite effect on the above indexes. RNA-sequencing data revealed that the Wnt and Notch pathways were involved in the CCT6A'effect on SCC-15 cell functions. CCT6A positively regulates the Wnt and Notch pathways in SCC-15 and HSC-3 cells. Importantly, it was shown that activation of the Wnt or Notch pathways attenuated the effect of CCT6A knockout on SCC-15 cell survival, invasion, and stemness. CCT6A may promote OSCC malignant behavior and stemness by activating the Wnt and Notch pathways.

Cardiovascular adverse events and immune-related adverse events associated with PD-1/PD-L1 inhibitors for head and neck squamous cell carcinoma (HNSCC)

While some literature has provided limited information about the potential cardiovascular risk and immune-related adverse events (irAEs) risk associated with PD-1/PD-L1 inhibitors in the treatment of Head and Neck Squamous Cell Carcinoma (HNSCC), the exact relevance is still uncertain. To assess the pharmacovigilance (PV), constituent ratio, severity, and reaction outcomes of major adverse cardiovascular events (MACE) and immune-related adverse events (irAEs) related to PD-1/PD-L1 inhibitors for HNSCC reported to the United States Food and Drug Administration Adverse Event Reporting System (FAERS). We analyzed reports of cardiovascular adverse events and irAEs associated with drug therapy for HNSCC submitted to FAERS from the 1st quarter 2015 to the 3rd quarter of 2023. Three PD-1/PD-L1 inhibitors were identified: nivolumab, pembrolizumab and durvalumab. Our primary composite endpoint was the PV of MACE and irAEs related to PD-1/PD-L1 inhibitors in the treatment of HNSCC, and the secondary endpoint was PV of other cardiovascular events. The software implemented was STATA 17.0 MP. 19,372 suspected drug-adverse event reports related to drug treatment in patients with HNSCC were identified, of which 916 reports were cardiovascular events, including 555 reports of MACE and 361 reports of other cardiovascular events. The PV signal regarding MACE was detected in durvalumab (PRR  = 2.12, 95% CI: 1.24-3.61; χ2  = 7.71; ROR  = 2.19, 95% CI: 1.24-3.86; IC  = 1.01; IC025  = 0.07) but not in nivolumab and pembrolizumab. The constituent ratio of MACE in all adverse events caused by nivolumab (OR  = 0.38, 95% CI: 0.19-0.73) and pembrolizumab (OR  = 0.48, 95% CI: 0.23-0.99) was significantly decreased, compared with durvalumab. A PV signal about other cardiovascular events was detected in durvalumab (PRR  = 3.04, 95% CI: 1.73-5.31; χ2  = 16.13; ROR  = 3.15, 95% CI: 1.74-5.70; IC  = 1.46; IC025  = 0.48), but it was not detected in nivolumab or pembrolizumab. The constituent ratio of other cardiovascular events in all adverse events caused by nivolumab (OR  = 0.25, 95% CI: 0.13-0.48) and pembrolizumab (OR  = 0.40, 95% CI: 0.20-0.80) was significantly decreased, compared with durvalumab. The constituent ratio of other cardiovascular events in all adverse events caused by nivolumab (OR  = 0.61, 95% CI: 0.38-0.99) was significantly decreased, compared with pembrolizumab. There were 40 cases of hypertension. A PV signal about hypertension was detected in pembrolizumab (PRR  = 3.72, 95% CI: 1.87-7.43; χ2  = 15.99; ROR  = 3.75, 95% CI: 1.87-7.51; IC  = 1.53, IC025  = 0.45), but it was not detected in nivolumab. The constituent ratio of hypertension in all adverse events caused by nivolumab (OR  = 0.09, 95% CI: 0.09-0.39) was significantly decreased, compared with pembrolizumab. There were 737 cases of irAEs. A PV signal about irAEs was detected in nivolumab (PPR  = 1.27, 95% CI: 1.05-1.53; χ2  = 6.38; ROR  = 1.28, 95% CI: 1.06-1.56; IC  = 0.29, IC025  = -0.00) and pembrolizumab (PPR  = 2.20, 95% CI: 1.79-2.71; χ2  = 56.55; ROR  = 2.31, 95% CI: 1.84-2.88; IC  = 1.03; IC025  = 0.68), but it was not detected in durvalumab. The constituent ratio of irAEs in all adverse events caused by nivolumab (OR  = 0.58, 95% CI: 0.44-0.76) significantly decreased, compared with pembrolizumab. By comparing the PV signals, constituent ratio, severity, and reaction outcome of the three drugs, we suppose that nivolumab can be used as the safest PD-1/PD-L1 inhibitor for HNSCC.

RNAs in tumour-derived extracellular vesicles and their significance in the tumour microenvironment

Small extracellular vesicles (sEVs) secreted by various types of cells serve as crucial mediators of intercellular communication within the complex tumour microenvironment (TME). Tumour-derived small extracellular vesicles (TDEs) are massively produced and released by tumour cells, recapitulating the specificity of their cell of origin. TDEs encapsulate a variety of RNA species, especially messenger RNAs, microRNAs, long non-coding RNAs, and circular RNAs, which release to the TME plays multifaced roles in cancer progression through mediating cell proliferation, invasion, angiogenesis, and immune evasion. sEVs act as natural delivery vehicles of RNAs and can serve as useful targets for cancer therapy. This review article provides an overview of recent studies on TDEs and their RNA cargo, with emphasis on the role of these RNAs in carcinogenesis.

The Notch inhibitor, FLI-06, increases the chemosensitivity of head and neck Squamous cell carcinoma cells to taxanes-based treatment

Aberration of Notch signaling is one of the key events involved in the development and progression of head and neck squamous cell carcinoma (HNSCC). The Notch pathway controls the tissue-specific differentiation of normal squamous epithelial cells and is frequently altered in squamous carcinomas, thus affecting their proliferation, growth, survival, and chemosensitivity or resistance against anti-cancer agents. In this study, we show that the use of novel, small-molecule inhibitors of Notch signaling, such as FLI-06, can have a beneficial effect on increasing the chemosensitivity of HNSCC to taxane-based chemotherapy. Inhibition of Notch signaling by FLI-06 alone virtually blocks the proliferation and growth of HNSCC cells in both 2D and 3D cultures and the zebrafish model, which is accompanied by down-regulation of key Notch target genes and proteins. Mechanistically, FLI-06 treatment causes cell cycle arrest in the G1-phase and induction of apoptosis in HNSCC, which is accompanied by increased c-JunS63 phosphorylation. Combining FLI-06 with Docetaxel shows a synergistic effect and partially blocks the cell growth of aggressive HNSCC cells via enhanced apoptosis and modification of c-JunS243 phosphorylation via GSK-3β inhibition. In conclusion, inhibition of Notch signaling in HNSCC cells that retain active Notch signaling significantly supports taxane-based anticancer activities via modulation of both the GSK-3β and the c-Jun.

Identification of MUC1-C as a Target for Suppressing Progression of Head and Neck Squamous Cell Carcinomas

The MUC1-C protein is aberrantly expressed in adenocarcinomas of epithelial barrier tissues and contributes to their progression. Less is known about involvement of MUC1-C in the pathogenesis of squamous cell carcinomas (SCC). Here, we report that the MUC1 gene is upregulated in advanced head and neck SCCs (HNSCC). Studies of HNSCC cell lines demonstrate that the MUC1-C subunit regulates expression of (i) RIG-I and MDA5 pattern recognition receptors, (ii) STAT1 and IFN regulatory factors, and (iii) downstream IFN-stimulated genes. MUC1-C integrates chronic activation of the STAT1 inflammatory pathway with induction of the ∆Np63 and SOX2 genes that are aberrantly expressed in HNSCCs. In extending those dependencies, we demonstrate that MUC1-C is necessary for NOTCH3 expression, self-renewal capacity, and tumorigenicity. The findings that MUC1 associates with ∆Np63, SOX2 and NOTCH3 expression by single-cell RNA sequencing analysis further indicate that MUC1-C drives the HNSCC stem cell state and is a target for suppressing HNSCC progression.

SIGNIFICANCE

This work reports a previously unrecognized role for MUC1-C in driving STAT1-mediated chronic inflammation with the progression of HNSCC and identifies MUC1-C as a druggable target for advanced HNSCC treatment.

MYO5A overexpression promotes invasion and correlates with low lymphocyte infiltration in head and neck squamous carcinoma

Head and neck squamous carcinoma (HNSC) poses a significant public health challenge due to its substantial morbidity. Nevertheless, despite advances in current treatments, the prognosis for HNSC remains unsatisfactory. To address this, single-cell RNA sequencing (RNA-seq) and bulk RNA-seq data combined with in vitro studies were conducted to examine the role of MYO5A (Myosin VA) in HNSC. Our investigation revealed an overexpression of MYO5A in HNSC that promotes HNSC migration in vitro. Remarkably, knockdown of MYO5A suppressed vimentin expression. Furthermore, analyzing the TCGA database evidenced that MYO5A is a risk factor for human papillomavirus positive (HPV+) HNSC (HR = 0.81, P < 0.001). In high MYO5A expression HNSC, there was a low count of tumor infiltrating lymphocytes (TIL), including activated CD4+ T cells, CD8+ T cells, and B cells. Of note, CD4+ T cells and B cells were positively associated with improved HPV+ HNSC outcomes. Correlation analysis demonstrated a decreased level of immunostimulators in high MYO5A-expressing HNSC. Collectively, these findings suggest that MYO5A may promote HNSC migration through vimentin and involve itself in the process of immune infiltration in HNSC, advancing the understanding of the mechanisms and treatment of HNSC.

Recent Advances in the Targeting of Head and Neck Cancer Stem Cells

Head and neck squamous cell carcinoma (HNSCC) is a very heterogeneous cancer with a poor overall response to therapy. One of the reasons for this therapy resistance could be cancer stem cells (CSCs), a small population of cancer cells with self-renewal and tumor-initiating abilities. Tumor cell heterogeneity represents hurdles for therapeutic elimination of CSCs. Different signaling pathway activations, such as Wnt, Notch, and Sonic-Hedgehog (SHh) pathways, lead to the expression of several cancer stem factors that enable the maintenance of CSC features. Identification and isolation of CSCs are based either on markers (CD133, CD44, and aldehyde dehydrogenase (ALDH)), side populations, or their sphere-forming ability. A key challenge in cancer therapy targeting CSCs is overcoming chemotherapy and radiotherapy resistance. However, in novel therapies, various approaches are being employed to address this hurdle such as targeting cell surface markers, other stem cell markers, and different signaling or metabolic pathways, but also, introducing checkpoint inhibitors and natural compounds into the therapy can be beneficial.

Optimization of a Three-Dimensional Culturing Method for Assessing the Impact of Cisplatin on Notch Signaling in Head and Neck Squamous Cell Carcinoma (HNSCC)

Head and neck squamous cell carcinoma (HNSCC) is a prevalent cancer type, with cisplatin being a primary treatment approach. However, drug resistance and therapy failure pose a significant challenge, affecting nearly 50% of patients over time. This research had two aims: (1) to optimize a 3D cell-culture method for assessing the interplay between tumor cells and cancer-associated fibroblasts (CAFs) in vitro; and (2) to study how cisplatin impacts the Notch pathway, particularly considering the role of CAFs. Using our optimized "3D sheet model" approach, we tested two HNSCC cell lines with different cisplatin sensitivities and moderate, non-mutated NOTCH1 and -3 expressions. Combining cisplatin with a γ-secretase inhibitor (crenigacestat) increased sensitivity and induced cell death in the less sensitive cell line, while cisplatin alone was more effective in the moderately sensitive line and sensitivity decreased with the Notch inhibitor. Cisplatin boosted the expression of core Notch signaling proteins in 3D monocultures of both lines, which was counteracted by crenigacestat. In contrast, the presence of patient-derived CAFs mitigated effects and protected both cell lines from cisplatin toxicity. Elevated NOTCH1 and NOTCH3 protein levels were consistently correlated with reduced cisplatin sensitivity and increased cell survival. Additionally, the Notch ligand JAG2 had additional, protective effects reducing cell death from cisplatin exposure. In summary, we observed an inverse relationship between NOTCH1 and NOTCH3 levels and cisplatin responsiveness, overall protective effects by CAFs, and a potential link between JAG2 expression with tumor cell survival.

Oral squamous cell carcinomas: state of the field and emerging directions

Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% of oral malignancies and impairs appearance, pronunciation, swallowing, and flavor perception. In 2020, 377,713 OSCC cases were reported globally. According to the Global Cancer Observatory (GCO), the incidence of OSCC will rise by approximately 40% by 2040, accompanied by a growth in mortality. Persistent exposure to various risk factors, including tobacco, alcohol, betel quid (BQ), and human papillomavirus (HPV), will lead to the development of oral potentially malignant disorders (OPMDs), which are oral mucosal lesions with an increased risk of developing into OSCC. Complex and multifactorial, the oncogenesis process involves genetic alteration, epigenetic modification, and a dysregulated tumor microenvironment. Although various therapeutic interventions, such as chemotherapy, radiation, immunotherapy, and nanomedicine, have been proposed to prevent or treat OSCC and OPMDs, understanding the mechanism of malignancies will facilitate the identification of therapeutic and prognostic factors, thereby improving the efficacy of treatment for OSCC patients. This review summarizes the mechanisms involved in OSCC. Moreover, the current therapeutic interventions and prognostic methods for OSCC and OPMDs are discussed to facilitate comprehension and provide several prospective outlooks for the fields.

Modulation of Notch Signaling by Small-Molecular Compounds and Its Potential in Anticancer Studies

Notch signaling is responsible for conveying messages between cells through direct contact, playing a pivotal role in tissue development and homeostasis. The modulation of Notch-related processes, such as cell growth, differentiation, viability, and cell fate, offer opportunities to better understand and prevent disease progression, including cancer. Currently, research efforts are mainly focused on attempts to inhibit Notch signaling in tumors with strong oncogenic, gain-of-function (GoF) or hyperactivation of Notch signaling. The goal is to reduce the growth and proliferation of cancer cells, interfere with neo-angiogenesis, increase chemosensitivity, potentially target cancer stem cells, tumor dormancy, and invasion, and induce apoptosis. Attempts to pharmacologically enhance or restore disturbed Notch signaling for anticancer therapies are less frequent. However, in some cancer types, such as squamous cell carcinomas, preferentially, loss-of-function (LoF) mutations have been confirmed, and restoring but not blocking Notch functions may be beneficial for therapy. The modulation of Notch signaling can be performed at several key levels related to NOTCH receptor expression, translation, posttranslational (proteolytic) processing, glycosylation, transport, and activation. This further includes blocking the interaction with Notch-related nuclear DNA transcription. Examples of small-molecular chemical compounds, that modulate individual elements of Notch signaling at the mentioned levels, have been described in the recent literature.

The value of lymphocyte to monocyte ratio in the prognosis of head and neck squamous cell carcinoma: a meta-analysis

Objectives

Although lymphocyte-monocyte ratio (LMR) is a potential prognostic biomarker in many tumor indications, a doubt occurs around its association with head and neck squamous cell carcinoma (HNSCC). We aimed to evaluate the predictive value of LMR in patients with HNSCC.

Methods

We searched PubMed, Web of Science, EMBASE, and the Cochrane database from inception to May 8, 2023 for systematic review and meta-analysis on LMR and outcomes related to HNSCC development. STATA software was used to estimate the correlation between LMR and prognosis. The risk ratio (hazard ratio, HR) and 95% confidence interval l (CI) for overall survival (OS), disease-free survival (DFS), cancer-specific survival (CSS), and progression-free survival (PFS) were calculated, and the association between LMR and OS was further validated by subgroup analysis. The source of heterogeneity with the results of subgroup analysis was analyzed by meta-regression analysis. This meta-analysis was registered at PROSPERO (CRD42023418766).

Results

After a comprehensive exploration, the results of 16 selected articles containing 5,234 subjects were evaluated. A raised LMR was connected to improved OS (HR = 1.36% CI [1.14-1.62] P = 0.018), DFS (HR = 0.942, 95% CI [0.631-1.382], P = 0.02), and PFS (HR = 0.932, 95% CI [0.527-1.589], P < 0.022). Subgroup analysis indicated that patients with a low LMR level had a poor prognosis with a critical value of ≥4. The LMR was found to be prognostic for cases with an LMR of <4. The meta-regression analysis showed that the cut-off values and treatment methods were the primary sources of high heterogeneity in patients with HNSCC.

Conclusions

Our study suggested that an elevated LMR is a potential prognostic biomarker in patients with HNSCC and could be used to predict patient outcomes.

Tumor microenvironmental modification by the current target therapy for head and neck squamous cell carcinoma

Current clinical and observational evidence supports the EXTREME regimen as one of the standards of care for patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) followed by the administration of immune checkpoint inhibitors (ICIs). In addition to the inhibition of the epidermal growth factor receptor (EGFR) pathway, cetuximab-mediated EGFR blockade has been shown to modulate tumor microenvironment (TME) characteristics, such as antibody-dependent cellular cytotoxicity (ADCC) activity, cytotoxic T-lymphocyte (CTL) infiltration into the tumor, anti-angiogenesis activity, and cytokine secretion via associated natural killer (NK) cells, etc.. On the other hand, there are reports that nivolumab affects the TME via Programmed cell death 1 (PD-1) inhibition, Interleukin-10 upregulation via T-cells, myeloid-derived suppressor cell-mediated immune escape induction, and tumor vessel perfusion by promoting CD8 + T-cell accumulation and Interferon-γ production in treatment-sensitive tumor cells. Actually, nivolumab administration can give T cells in the TME both immune superiority and inferiority. HNSCC treatment using cetuximab increases the frequency of FoxP3 + intratumoral effector regulatory T cells (Tregs) expressing CTL associated antigen (CTLA)-4, and targeting CTLA-4 + Tregs using ipilimumab restores the cytolytic function of NK cells, which mediate ADCC activity. Treg-mediated immune suppression also contributes to clinical response to cetuximab treatment, suggesting the possibility of the addition of ipilimumab or the use of other Treg ablation strategies to promote antitumor immunity. Moreover, also in hyper progression disease (HPD), intratumoral frequency of FoxP3 + effector Tregs expressing CTLA-4 is increased. Therefore, combination treatment with cetuximab plus anti-CTLA-4 antibody ipilimumab for HNSCC and this combination therapy after nivolumab administration for HPD may be expected to result in a higher tumor-control response. Based on the above evidence, we here suggest the efficacy of using these therapeutic strategies for patients with local-advanced, recurrent, and metastatic HNSCC and patients who do not respond well to nivolumab administration.

Identification of novel prognostic indicators for oral squamous cell carcinoma based on proteomics and metabolomics

BACKGROUND

The low 5-year survival rate of oral squamous cell carcinoma (OSCC) suggests that new prognostic indicators need to be identified to aid the clinical management of patients.

METHODS

Saliva samples from OSCC patients and healthy controls were collected for proteomic and metabolomic sequencing. Gene expressed profiling was downloaded from TCGA and GEO databases. After the differential analysis, proteins with a significant impact on the prognosis of OSCC patients were screened. Correlation analysis was performed with metabolites and core proteins were identified. Cox regression analysis was utilized to stratify OSCC samples based on core proteins. The prognostic predictive ability of the core protein was then evaluated. Differences in infiltration of immune cells between the different strata were identified.

RESULTS

There were 678 differentially expressed proteins (DEPs), 94 intersected DEPs among them by intersecting with differentially expressed genes in TCGA and GSE30784 dataset. Seven core proteins were identified that significantly affected OSCC patient survival and strongly correlated with differential metabolites (R² > 0.8). The samples were divided into high- and low-risk groups according to median risk score. The risk score and core proteins were well prognostic factor in OSCC patients. Genes in high-risk group were enriched in Notch signaling pathway, epithelial mesenchymal transition (EMT), and angiogenesis. Core proteins were strongly associated with the immune status of OSCC patients.

CONCLUSIONS

The results established a 7-protein signatures with the hope of early detection and the capacity for risk assessment of OSCC patient prognosis. Further providing more potential targets for the treatment of OSCC.

Targeting PI3K/AKT/mTOR Signaling Pathway as a Radiosensitization in Head and Neck Squamous Cell Carcinomas

Globally, there are over half a million new patients with head and neck squamous cell carcinomas (HNSCC) every year. The current therapeutic approaches to HNSCC are surgery and adjuvant radiotherapy. These approaches carry a high incidence of metastasis or recurrence from HNSCC cells' radioresistance. Recent studies have revealed that a combination with radiosensitizers can be used to improve the radioresistance in HNSCC; however, few agents are approved as radiosensitizers. The constitutive activation of phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is a vitally oncogenic type of signaling that promotes tumorigenesis, metastasis, and radiotherapy resistance in HNSCC. Pharmacological targeting of PI3K/AKT/mTOR signaling pathway is considered a promising strategy of radiosensitization in HNSCC. In this review, we summarize the oncogenic significance of PI3K/AKT/mTOR signaling in HNSCC with radiotherapy resistance and highlight the therapeutic potential of small molecule inhibitors against PI3K/AKT/mTOR signaling for the radiosensitization in HNSCC treatment. It provides a mechanistic framework for the development of new drugs for radiosensitization in HNSCC radiotherapy via targeting PI3K/AKT/mTOR signaling pathway.

Curcuminoids as Modulators of EMT in Invasive Cancers: A Review of Molecular Targets With the Contribution of Malignant Mesothelioma Studies

Curcuminoids, which include natural acyclic diarylheptanoids and the synthetic analogs of curcumin, have considerable potential for fighting against all the characteristics of invasive cancers. The epithelial-to-mesenchymal transition (EMT) is a fundamental process for embryonic morphogenesis, however, the last decade has confirmed it orchestrates many features of cancer invasiveness, such as tumor cell stemness, metabolic rewiring, and drug resistance. A wealth of studies has revealed EMT in cancer is in fact driven by an increasing number of parameters, and thus understanding its complexity has now become a cornerstone for defining future therapeutic strategies dealing with cancer progression and metastasis. A specificity of curcuminoids is their ability to target multiple molecular targets, modulate several signaling pathways, modify tumor microenvironments and enhance the host’s immune response. Although the effects of curcumin on these various parameters have been the subject of many reviews, the role of curcuminoids against EMT in the context of cancer have never been reviewed so far. This review first provides an updated overview of all EMT drivers, including signaling pathways, transcription factors, non-coding RNAs (ncRNAs) and tumor microenvironment components, with a special focus on the most recent findings. Secondly, for each of these drivers the effects of curcumin/curcuminoids on specific molecular targets are analyzed. Finally, we address some common findings observed between data reported in the literature and the results of investigations we conducted on experimental malignant mesothelioma, a model of invasive cancer representing a useful tool for studies on EMT and cancer.

Roles of Notch Signaling in the Tumor Microenvironment

The Notch signaling pathway is an architecturally simple signaling mechanism, well known for its role in cell fate regulation during organ development and in tissue homeostasis. In keeping with its importance for normal development, dysregulation of Notch signaling is increasingly associated with different types of tumors, and proteins in the Notch signaling pathway can act as oncogenes or tumor suppressors, depending on the cellular context and tumor type. In addition to a role as a driver of tumor initiation and progression in the tumor cells carrying oncogenic mutations, it is an emerging realization that Notch signaling also plays a role in non-mutated cells in the tumor microenvironment. In this review, we discuss how aberrant Notch signaling can affect three types of cells in the tumor stroma-cancer-associated fibroblasts, immune cells and vascular cells-and how this influences their interactions with the tumor cells. Insights into the roles of Notch in cells of the tumor environment and the impact on tumor-stroma interactions will lead to a deeper understanding of Notch signaling in cancer and inspire new strategies for Notch-based tumor therapy.

Diagnostics of HNSCC Patients: An Analysis of Cell Lines and Patient-Derived Xenograft Models for Personalized Therapeutical Medicine

Head and neck squamous cell carcinomas (HNSCC) are very frequent worldwide, and smoking and chronic alcohol use are recognized as the main risk factors. For oropharyngeal cancers, HPV 16 infection is known to be a risk factor as well. By employing next-generation sequencing, both HPV-positive and negative HNSCC patients were detected as positive for PI3K mutation, which was considered an optimal molecular target. We analyzed scientific literature published in the last 5 years regarding the newly available diagnostic platform for targeted therapy of HNSCC HPV+/−, using HNSCC-derived cell lines cultures and HNSCC pdx (patient-derived xenografts). The research results are promising and require optimal implementation in the management of HNSCC patients.