Hypoxia-inducible factors in OSCC

Current Drug Delivery Strategies for Buccal Cavity Ailments using Mouth Dissolving Wafer Technology: A Comprehensive Review on the Present State of the Art

BACKGROUND

Mouth-dissolving wafer is polymer-based matrice that incorporates various pharmaceutical agents for oral drug delivery. This polymeric wafer is ingenious in the way that it needs not be administered with water, like in conventional tablet dosage form. It has better compliance among the pediatric and geriatric groups owing to its ease of administration.

OBJECTIVE

The polymeric wafer dissolves quickly in the oral cavity and is highly effective for a targeted local effect in buccal-specific ailments. It is a safe, effective, and versatile drug delivery carrier for a range of drugs used to treat a plethora of oral cavity-specific ailments that inflict common people, like thrush, canker sores, periodontal disease, benign oral cavity tumors, buccal neoplasm, and malignancies. This review paper focuses thoroughly on the present state of the art in mouth-dissolving wafer technology for buccal drug delivery and targeting. Moreover, we have also addressed present-time limitations associated with wafer technology to aid researchers in future developments in the arena of buccal drug delivery.

CONCLUSION

This dynamic novel formulation has tremendous future implications for designing drug delivery systems to target pernicious ailments and diseases specific to the buccal mucosa. In a nutshell, this review paper aims to summarize the present state of the art in buccal targeted drug delivery.

Panoramic view of key cross-talks underpinning the oral squamous cell carcinoma stemness - unearthing the future opportunities

The clinical management of oral cancer is often frequented with challenges that arise from relapse, recurrence, invasion and resistance towards the cornerstone chemo and radiation therapies. The recent conceptual advancement in oncology has substantiated the role of cancer stem cells (CSC) as a predominant player of these intricacies. CSC are a sub-group of tumor population with inherent adroitness to self-renew with high plasticity. During tumor evolution, the structural and functional reprogramming persuades the cancer cells to acquire stem-cell like properties, thus presenting them with higher survival abilities and treatment resistance. An appraisal on key features that govern the stemness is of prime importance to confront the current challenges encountered in oral cancer. The nurturing niche of CSC for maintaining its stemness characteristics is thought to be modulated by complex multi-layered components encompassing neoplastic cells, extracellular matrix, acellular components, circulatory vessels, various cascading signaling molecules and stromal cells. This review focuses on recapitulating both intrinsic and extrinsic mechanisms that impart the stemness. There are contemplating evidences that demonstrate the role of transcription factors (TF) in sustaining the neoplastic stem cell's pluripotency and plasticity alongside the miRNA in regulation of crucial genes involved in the transformation of normal oral mucosa to malignancy. This review illustrates the interplay between miRNA and various known TF of oral cancer such as c-Myc, SOX, STAT, NANOG and OCT in orchestrating the stemness and resistance features. Further, the cross-talks involved in tumor micro-environment inclusive of cytokines, macrophages, extra cellular matrix, angiogenesis leading pathways and influential factors of hypoxia on tumorigenesis and CSC survival have been elucidated. Finally, external factorial influence of oral microbiome gained due to the dysbiosis is also emphasized. There are growing confirmations of the possible roles of microbiomes in the progression of oral cancer. Given this, an attempt has been made to explore the potential links including EMT and signaling pathways towards resistance and stemness. This review provides a spectrum of understanding on stemness and progression of oral cancers at various regulatory levels along with their current therapeutic knowledge. These mechanisms could be exploited for future research to expand potential treatment strategies.

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.

Prognostic model based on telomere-related genes predicts the risk of oral squamous cell carcinoma

BACKGROUND

This study investigated a potential prognostic model based on telomere-related genes (TRGs) for the clinical prediction of oral squamous cell carcinoma (OSCC).

METHODS

Gene expression data and associated clinical phenotypes were obtained from online databases. Differentially expressed (DE)-TRGs were identified between OSCC and normal samples, followed by protein-protein interaction and enrichment analyses. Subsequently, the prognostic genes explored based on the DE-TRGs and survival data were applied in the establishment of the current prognostic model, and an integrated analysis was performed between high- and low-risk groups using a prognostic model. The expression of certain prognostic genes identified in the present study was validated using qPCR analysis and/or western blot in OSCC cell lines and clinical samples.

RESULTS

169 DE-TRGs were identified between the OSCC samples and controls. DE-TRGs are mainly involved in functions such as hypoxia response and pathways such as the cell cycle. Eight TRGs (CCNB1, PDK4, PLOD2, RACGAP1, MET, PLK1, KPNA2, and CCNA2) associated with OSCC survival and prognosis were used to construct a prognostic model. qPCR analysis and western blot showed that most of the eight prognostic genes were consistent with the current bioinformatics results. Analysis of the high- and low-risk groups for OSCC determined by the prognostic model showed that the current prognostic model was reliable.

CONCLUSIONS

A novel prognostic model for OSCC was constructed by TRGs. PLOD2 and APLK1 may participate in the progression of OSCC via responses to hypoxia and cell cycle pathways, respectively. TRGs, including KPNA2 and CCNA2, may serve as novel prognostic biomarkers for OSCC.

Mussel-Inspired Tantalum Nanocomposite Hydrogels for In Situ Oral Cancer Treatment

Oral squamous cell carcinoma (OSCC) is one of the most common oral malignancies. Radiotherapy is the primary noninvasive treatment of OSCC for avoiding surgery-induced facial deformities and impaired oral function. However, the specificity of in situ OSCC limits radiotherapeutic effects because of the hypoxia-induced low radiosensitivity of tumors and the low radiation tolerance of surrounding normal tissues. Here, we design a highly efficient and low-toxic radiosensitization strategy. On the one hand, biocompatible poly(vinyl pyrrolidone)-modified tantalum nanoparticles (Ta@PVP NPs) not only have strong X-ray deposition capability to upregulate oxidative stress but also have photothermal conversion efficiency to improve hypoxia for tumor radiosensitivity. On the other hand, to optimize the spatial distribution of Ta@PVP NPs within tumors, mussel-inspired catechol with bioadhesive properties is grafted on tumor microenvironment-responsive sodium alginate (DAA) to form in situ hydrogels for precision radiotherapy. On this basis, we find that Ta@PVP-DAA hydrogels effectively inhibit OSCC development in mice under photothermal-assisted radiotherapy without facial deformities and damage to surrounding normal tissues. Overall, our work not only promotes the exploration of Ta@PVP NPs as new radiosensitizers for OSCC but also develops a nanocomposite hydrogel system strategy as a promising paradigm for the precision treatment of orthotopic tumors.

Overexpression of Hypoxia-Inducible Factor-1α and Its Relation with Aggressiveness and Grade of Oral Squamous Cell Carcinoma

Hypoxia-inducible factor-1α (HIF-1α) has been shown to be involved in cancer metastasis in several cancer types. There is however conflicting evidence of HIF-1α expression with oral cancer prognosis. Therefore, this study set out to investigate HIF-1α overexpression and its relationship with the aggressiveness and grade of oral squamous cell carcinoma (OSCC) and to explore the diagnostic potential of HIF-1α overexpression in OSCC in a cohort of Pakistani patients. Immunostaining of HIF-1α was performed on 54 OSCC and 14 normal oral mucosa (NOM) tissue samples and various cut-offs were used to evaluate its immunohistochemical expression. HIF-1α expression in OSCC samples was significantly higher than in controls, with minimal immunoreactivity in NOM. HIF-1α overexpression was significantly associated with increased tumor size (p = 0.046). However, no association was found between HIF-1α overexpression and increasing Broder's histological grade or TNM stage. The cut-off >10% cells with moderate to marked intensity carried a sensitivity of 70% and a specificity of 100% to distinguish between tumor and control. ROC curve analysis of HIF-1α weighted histoscores showedHIF-1α overexpression as a highly sensitive and specific diagnostic test (p < 0.001, AUC = 0.833). HIF-1α overexpression is a tumor-specific finding associated with increased tumor size and carries a potential diagnostic role.

Effect of regulatory cell death on the occurrence and development of head and neck squamous cell carcinoma

Head and neck cancer is a malignant tumour with a high mortality rate characterized by late diagnosis, high recurrence and metastasis rates, and poor prognosis. Head and neck squamous cell carcinoma (HNSCC) is the most common type of head and neck cancer. Various factors are involved in the occurrence and development of HNSCC, including external inflammatory stimuli and oncogenic viral infections. In recent years, studies on the regulation of cell death have provided new insights into the biology and therapeutic response of HNSCC, such as apoptosis, necroptosis, pyroptosis, autophagy, ferroptosis, and recently the newly discovered cuproptosis. We explored how various cell deaths act as a unique defence mechanism against cancer emergence and how they can be exploited to inhibit tumorigenesis and progression, thus introducing regulatory cell death (RCD) as a novel strategy for tumour therapy. In contrast to accidental cell death, RCD is controlled by specific signal transduction pathways, including TP53 signalling, KRAS signalling, NOTCH signalling, hypoxia signalling, and metabolic reprogramming. In this review, we describe the molecular mechanisms of nonapoptotic RCD and its relationship to HNSCC and discuss the crosstalk between relevant signalling pathways in HNSCC cells. We also highlight novel approaches to tumour elimination through RCD.

Hypoxia-related LncRNAs signature predicts prognosis and is associated with immune infiltration and progress of head and neck squamous cell carcinoma

Background

Disclosing prognostic information is necessary to enable good treatment selection and improve patient outcomes. Previous studies suggest that hypoxia is associated with an adverse prognosis in patients with HNSCC and that long non-coding RNAs (lncRNAs) show functions in hypoxia-associated cancer biology. Nevertheless, the understanding of lncRNAs in hypoxia related HNSCC progression remains confusing.

Methods

Data were downloaded from TCGA and GEO database. Bioinformatic tools including R packages GEOquery, limma, pheatmap, ggplot2, clusterProfiler, survivalROC and survcomp and LASSO cox analysis were utilized. Si-RNA transfection, CCK8 and real-time quantified PCR were used in functional study.

Results

GEO data (GSE182734) revealed that lncRNA regulation may be important in hypoxia related response of HNSCC cell lines. Further analysis in TCGA data identified 314 HRLs via coexpression analysis between differentially expressed lncRNAs and hypoxia-related mRNAs. 23 HRLs were selected to build the prognosis predicting model using lasso Cox regression analyses. Our model showed excellent performance in predicting survival outcomes among patients with HNSCC in both the training and validation sets. We also found that the risk scores were related to tumor stage and to tumor immune infiltration. Moreover, LINC01116 were selected as a functional study target. The knockdown of LINC01116 significantly inhibited the proliferation of HNSCC cells and effected the hypoxia induced immune and the NF-κB/AKT signaling.

Conclusions

Data analysis of large cohorts and functional experimental validation in our study suggest that hypoxia related lncRNAs play an important role in the progression of HNSCC, and its expression model can be used for prognostic prediction.

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NcRNAs regulations showed significance in hypoxia related response in HNSCC.

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314 lncRNAs coexpressed with hypoxia marker genes were identified as HRLs.

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An effective HRLs prognosis prediction model had been constructed and validated.

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Immune cells and pathways paly roles in hypoxia related progress of HNSCC.

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LINC01116 regulates HNSCC through hypoxia related immune and NF-κB/AKT signaling.

SNHG17/miR-384/ELF1 axis promotes cell growth by transcriptional regulation of CTNNB1 to activate Wnt/β-catenin pathway in oral squamous cell carcinoma

Increasing evidence proved the abnormal expression of long non-coding RNAs (lncRNAs) in various human malignancies, including oral squamous cell carcinoma (OSCC). Nevertheless, limited explorations concern the role of lncRNA small nucleolar RNA host gene 17 (SNHG17) in OSCC. Herein, SNHG17 was disclosed to be remarkably upregulated in OSCC cell lines and promoted OSCC cell growth. Further mechanistic studies, including DNA/RNA pull down, RIP, ChIP, and luciferase reporter gene assays, were conducted. It was confirmed that Wnt/β-catenin signaling pathway was involved in the SNHG17-mediated OSCC cell growth. Moreover, E74 like ETS transcription factor 1 (ELF1) was identified as the transcription activator of CTNNB1 (β-catenin mRNA) in OSCC. Inspired by competing for endogenous RNAs (ceRNAs) network, we were pleasantly surprised to find that SNHG17 and ELF1 functioned as ceRNAs in OSCC via competitively binding to microRNA-384 (miR-384). By using rescue assays, we revealed that SNHG17 facilitated OSCC cell growth through modulating miR-384/ELF1 axis. Importantly, we certified that ELF1 was indispensable for SNHG17-affected OSCC progression. Collectively, it can be concluded that SNHG17/miR-384/ELF1 axis contributed to OSCC cell growth via promoting CTNNB1 expression, thus activating Wnt/β-catenin signaling pathway.

A novel defined hypoxia-related gene signature to predict the prognosis of oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC), as the most common oral cancer globally, is very harmful to people's health. Hypoxia is closely related to many cancers. In this study, we have conducted a comprehensive exploration of the impact of hypoxia on OSCC.

Methods

First, we calculated the enrichment score (ES) of hypoxia-related genes in the sample based on the enrichment analysis of the single sample Gene Set Enrichment Analysis (ssGSEA) and expressed it as a potential hypoxia index (HPI). We first identified the relationship between HPI and survival time in OSCC tumor samples. Then we assessed the correlation between hypoxia and the degree of infiltration of various immune cells in OSCC tissues, and screened out gene mutations that may be related to HPI in OSCC. Finally, we constructed a prognostic model of hypoxia-related genes.

Results

In the immune cell infiltration of OSCC, we found that hypoxia was significantly related to the infiltration of eosinophils, macrophages, neutrophils, T helper cells and Th1 cells. In addition, NSD1 mutations may become a signal to suggest that patients with OSCC have higher HPI. Finally, we constructed a prognostic model of 6 sets of hypoxia-related genes (PGK1, JMJD6, S100A4, SLC2A3, DDIT4 and HK1) in OSCC.

Conclusions

Hypoxia is closely related to immune cell infiltration, gene mutation, and prognosis in OSCC patients.

The Molecular Basis and Therapeutic Aspects of Cisplatin Resistance in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a kind of malignant tumors with low survival rate and prone to have early metastasis and recurrence. Cisplatin is an alkylating agent which induces DNA damage through the formation of cisplatin-DNA adducts, leading to cell cycle arrest and apoptosis. In the management of advanced OSCC, cisplatin-based chemotherapy or chemoradiotherapy has been considered as the first-line treatment. Unfortunately, only a portion of OSCC patients can benefit from cisplatin treatment, both inherent resistance and acquired resistance greatly limit the efficacy of cisplatin and even cause treatment failure. Herein, this review outline the underlying mechanisms of cisplatin resistance in OSCC from the aspects of DNA damage and repair, epigenetic regulation, transport processes, programmed cell death and tumor microenvironment. In addition, this review summarizes the strategies applicable to overcome cisplatin resistance, which can provide new ideas to improve the clinical therapeutic outcome of OSCC.

Differentiated embryo chondrocyte 1, induced by hypoxia-inducible factor 1α, promotes cell migration in oral squamous cell carcinoma cell lines

OBJECTIVE

This study aimed to explore the correlation between differentiated embryo chondrocyte 1 (DEC1) and hypoxia-inducible factor 1α (HIF-1α) in oral squamous cell carcinoma (OSCC) and how they participate in tumor progression.

STUDY DESIGN

An immunohistochemical staining method was used to detect the expression of HIF-1α and DEC1 in 64 OSCC specimens, and the correlation between HIF-1α and DEC1 was analyzed. The expression of HIF-1α and DEC1 in OSCC cells under normoxic and hypoxic environments was assessed and analyzed by Western blotting and immunofluorescence. Furthermore, the DEC1 gene was silenced by siRNA and treated with cobalt chloride (CoCl₂) to analyze the effects that DEC1 and hypoxia might have on the migration ability of OSCC cells.

RESULTS

The expression of HIF-1α and DEC1 in OSCC was positively correlated. Using CoCl₂ to simulate a hypoxic environment increased the protein levels of HIF-1α and DEC1 in OSCC cells. The HIF-1α inhibitor LW6 decreased HIF-1α and DEC1 expression in OSCC cells in a hypoxic environment. Silencing the DEC1 gene reduced the migration ability of OSCC cells.

CONCLUSION

The hypoxic environment in OSCC could upregulate the expression of DEC1 by increasing the protein level of HIF-1α, and this process might be involved in the migration of tumor cells.

Current Understanding of the HIF-1-Dependent Metabolism in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the 10th most frequent human malignancy and is thus a global burden. Despite some progress in diagnosis and therapy, patients' overall survival rate, between 40 and 55%, has stagnated over the last four decades. Since the tumor node metastasis (TNM) system is not precise enough to predict the disease outcome, additive factors for diagnosis, prognosis, prediction and therapy resistance are urgently needed for OSCC. One promising candidate is the hypoxia inducible factor-1 (HIF-1), which functions as an early regulator of tumor aggressiveness and is a key promoter of energy adaptation. Other parameters comprise the composition of the tumor microenvironment, which determines the availability of nutrients and oxygen. In our opinion, these general processes are linked in the pathogenesis of OSCC. Based on this assumption, the review will summarize the major features of the HIF system-induced activities, its target proteins and related pathways of nutrient utilization and metabolism that are essential for the initiation, progression and therapeutic stratification of OSCC.

Hypoxia-Activated Prodrug Derivatives of Carbonic Anhydrase Inhibitors in Benzenesulfonamide Series: Synthesis and Biological Evaluation

Hypoxia, a common feature of solid tumours' microenvironment, is associated with an aggressive phenotype and is known to cause resistance to anticancer chemo- and radiotherapies. Tumour-associated carbonic anhydrases isoform IX (hCA IX), which is upregulated under hypoxia in many malignancies participating to the microenvironment acidosis, represents a valuable target for drug strategy against advanced solid tumours. To overcome cancer cell resistance and improve the efficacy of therapeutics, the use of bio-reducible prodrugs also known as Hypoxia-activated prodrugs (HAPs), represents an interesting strategy to be applied to target hCA IX isozyme through the design of selective carbonic anhydrase IX inhibitors (CAIs). Here, we report the design, synthesis and biological evaluations including CA inhibition assays, toxicity assays on zebrafish and viability assays on human cell lines (HT29 and HCT116) of new HAP-CAIs, harboring different bio-reducible moieties in nitroaromatic series and a benzenesulfonamide warhead to target hCA IX. The CA inhibition assays of this compound series showed a slight selectivity against hCA IX versus the cytosolic off-target hCA II and hCA I isozymes. Toxicity and viability assays have highlighted that the compound bearing the 2-nitroimidazole moiety possesses the lowest toxicity (LC50 of 1400 µM) and shows interesting results on viability assays.

SATB2 knockdown decreases hypoxia-induced autophagy and stemness in oral squamous cell carcinoma

Increasing evidence has suggested that special AT-rich sequence-binding protein 2 (SATB2) may be involved in the progression of numerous types of human cancer; however, the biological function of SATB2 in oral squamous cell carcinoma (OSCC) occurrence and progression remains relatively unknown. The present study aimed to investigate the potential role of SATB2 in the regulation of biological characteristics of OSSC during hypoxia. The expression of SATB2 in SCC9 cells was knocked down using small interfering RNA. Western blotting was used to determine the protein expression levels of SATB2, autophagy-related proteins microtubule-associated protein light chain (LC)3-I/II and Beclin-1, and stemness markers such as Oct-4 (POU class 5 homeobox 1), Sox-2 (SRY-box 2) and Nanog (nanog homeobox). Transmission electron microscopy and monodansylcadaverine staining were used to detect the presence of autophagosomes. Furthermore, the self-renewal capacity of cells was analyzed using colony forming assays; the cell proliferative, migratory and invasive ability were evaluated using CCK-8, wound healing and Transwell assays, respectively; and the cell cycle distribution and rate of apoptosis were detected using flow cytometry. The expression levels of SATB2, autophagy-related proteins and stemness markers were significantly increased in SCC9 cells following hypoxic treatment. Meanwhile, the genetic knockdown of SATB2 inhibited hypoxia-mediated autophagy by decreasing the expression levels of Beclin-1, and preventing the conversion of LC3-I to LC3-II and the accumulation of autophagosomes. The knockdown of SATB2 also inhibited the hypoxia-induced colony-forming ability and the expression of stemness markers. Functionally, it also inhibited the proliferative, migratory and invasive abilities of SCC9 cells, while inducing apoptosis and cell cycle arrest under hypoxia. In conclusion, the present study suggested that SATB2 may function as an oncogene in OSCC cells, and targeting SATB2 may be a potential therapeutic strategy for the treatment of OSCC.

Dissecting the Proton Transport Pathway in Oral Squamous Cell Carcinoma: State of the Art and Theranostics Implications

Cancer cells overexpress proton exchangers at the plasma membrane in order acidify the extracellular matrix and maintain the optimal pH for sustaining cancer growth. Among the families of proton exchangers implicated in carcinogenesis, carbonic anhydrases (CAs), monocarboxylate transporters (MCTs), Na⁺/H⁺ exchangers (NHEs), sodium bicarbonate cotransporters (NBCs), and vacuolar ATPases (V-ATPases) are highlighted. Considerable research has been carried out into the utility of the understanding of these machineries in the diagnosis and prognosis of several solid tumors. In addition, as therapeutic targets, the interference of their functions has contributed to the discovery or optimization of cancer therapies. According to recent reports, the study of these mechanisms seems promising in the particular case of oral squamous cell carcinoma (OSCC). In the present review, the latest advances in these fields are summarized, in particular, the usefulness of proton exchangers as potential prognostic biomarkers and therapeutic targets in OSCC.

Elevated microRNA-145 inhibits the development of oral squamous cell carcinoma through inactivating ERK/MAPK signaling pathway by down-regulating HOXA1

Background: Oral cancer is one of the most frequent solid cancers worldwide, and oral squamous cell carcinoma (OSCC) constitutes approximately 90% of oral cancers. The discovery of reliable prognostic indicators would be a potential strategy for OSCC treatment. In the present study, we aim to explore the underlying mechanism by which microRNA-145 (miR-145) affected OSCC. Methods: Forty-eight patients diagnosed with OSCC were enrolled to obtain the OSCC tissues and adjacent normal tissues. The targeting relationship between miR-145 and Homeobox A1 (HOXA1) was verified. In order to assess the effects of miR-145 in OSCC and the detailed regulatory mechanism, the SCC-9 cell line was adopted, in which expression of miR-145 and HOXA1 were altered by transfection. Then, a series of in vitro and in vivo experiments were performed to evaluate the cell viability, migration, invasion, and tumor growth. Results: miR-145 was poorly expressed and HOXA1 was highly expressed in OSCC. HOXA1 was verified as a target of miR-145 to mediate the activation of the extracellular signal-regulated kinase/mitogen activated protein kinase (ERK/MAPK) signaling pathway. In the circumstance of miR-145 elevation or HOXA1 depletion, the SCC-9 cell line manifested with inhibited cell viability, invasion, and migration in vitro, coupled with reduced tumor growth in vivo, with a decreased expression of ERK/MAPK signaling pathway-related genes/proteins. Conclusion: These findings suggested that miR-145 can inhibit HOXA1 to inactivate the ERK/MAPK signaling pathway, thereby suppressing OSCC cell proliferation, migration, and invasion to further inhibit the development of OSCC, highlighting a novel therapeutic target for the OSCC treatment.

Cancer Stem Cell based molecular predictors of tumor recurrence in Oral squamous cell carcinoma

OBJECTIVE

This study aimed to identify the cancer stem cell specific biomarkers that can be effective candidate prognosticators of oral squamous cell carcinoma.

DESIGN

Microarray-based meta-analysis derived transcriptional profile of head and neck cancers was compared with the Cancer Stem Cell database to arrive at a subset of markers. This subset was further co-related with clinico-pathological parameters, recurrence and survival of oral cancer patients (n = 313) in The Cancer Genome Atlas database and in oral cancer (n = 28) patients.

RESULTS

Meta-analysis in combination with database comparison identified a panel of 221 genes specific to head and neck cancers. Correlation of expression levels of these markers in the oral cancer cohort of The Cancer Genome Atlas (n = 313) with treatment outcome identified 54 genes (p < 0.05 or fold change >2) associated with disease recurrence, 8 genes (NQO1, UBE2C, EDNRB, FKBP4, STAT3, HOXA1, RIT1, AURKA) being significant with high fold change. Assessment of the efficacy of the subset (n = 54) as survival predictors identified an additional 4 genes (CDK1, GINS2, PHF5 A, ERBB2) that co-related with poor disease-free survival (p < 0.05). CDK1 showed a significant association with the clinical stage, margin status and with advanced pathological parameters. Initial patient validation indicated that CDK1 and NQO1 significantly co-related with the poor disease-free and overall survival (p < 0.05).

CONCLUSION

This panel of oral cancer specific, cancer stem cell associated markers identified in this study, a subset of which was validated, will be of clinical benefit subject to large scale validation studies.

Role of vitamin D and vitamin D receptor (VDR) in oral cancer

Oral cancer is known as one of the most common cancers, with a poor prognosis, related to delayed clinical diagnosis, either due to the lack of particular biomarkers related to the disease or costly therapeutic alternatives. Vitamin D executes its functions by interacting with the vitamin D receptor (VDR), both in healthy and diseased individuals, including oral cancer. This review discusses the role of vitamin D and VDR on tumorigenesis, emphasizing on oral cancer. Furthermore, regulation of VDR expression, mechanisms of anticancer effects of calcitriol, oral cancer chemoresistance and its relation with VDR and polymorphisms of VDR gene will be discussed. The manuscript is prepared mainly using the information collected from PubMed and MEDLINE.

Participation of hypoxia-inducible factor-1α and lymphangiogenesis in metastatic and non-metastatic lower lip squamous cell carcinoma

This study evaluated the lymphatic density and HIF-1α immunoexpression in lower lip squamous cell carcinoma (LLSCC) and their correlation with clinicopathological (nodal metastasis, clinical stage, histological grade, recurrence and disease outcome) and survival parameters in 20 metastatic and 20 non-metastatic LLSCCs. Lymphatic density was established by counting microvessels (D2-40⁺) at the tumor core (intratumoral lymphatic density, ILD) and at the invasive front (peritumoral lymphatic density, PLD) and percentages of immunopositive cells for HIF-1α were established. No statistically significant differences in lymphatic densities in relation to clinicopathological parameters were observed (P > 0.05). All cases exhibited nuclear and cytoplasmic HIF-1α immunoexpression, with relatively high percentages of positivity, but this expression was not statistically different in relation to clinicopathological variables (P > 0.05). Positive correlations were observed between ILD and PLD (P = 0.002), and between nuclear HIF-1α immunoexpression at the tumor core and ILD (P = 0.001). The results suggest ILD and PLD are not directly related to the development of lymph node metastasis in LLSCC. The striking expression of HIF-1α suggests the involvement of this protein in the etiopathogenesis of LLSCCs, possibly stimulating lymphangiogenesis at the tumor core. However, this protein does not seem to exert a determining influence on the biological aggressiveness of these tumors.

Immunohistochemical Evaluation of GLUT-3 and GLUT-4 in Oral Epithelial Dysplasia and Oral Squamous Cell Carcinoma

Objectives

To evaluate immunohistochemically the expression of GLUT-3 and GLUT-4 in oral epithelial dysplasia (OED) and the oral squamous cell carcinoma (OSCC) and assess possible involvement in the malignant transformation of oral lesions.

Methods

Tissue samples of 15 cases of OSCC and 15 of OED were subjected to immunohistochemistry with anti-GLUT-3 and anti-GLUT-4 antibodies. Five fields of each case were analyzed, to provide percentages of positive cells at 400X magnification.

Result

GLUT-3 and GLUT-4 were positive in 100% of the analyzed samples, the percentage immunolabeling for GLUT-3 ranging from 19% to 73% in the OED group and 10% to 89% in the OSCC group. Positive immunolabeling for GLUT-4 ranged from 15.2% to 79.9% in the OSCC group and 27.1% to 92.6% in the OED group. Statistical analysis with the Mann-Whitney test revealed that there was a higher expression of GLUT-4 in the OED group than in the OSCC group (p=0.04) without any significant difference in the GLUT-3 expression (p=0.852).

Conclusion

GLUT-4 expression may indicate some role in oncogenic mechanisms which can determine a malignant phenotype. Thus, it is suggested that further studies on the role of GLUT-3 in oral carcinogenesis be conducted.

Deubiquitination and stabilization of programmed cell death ligand 1 by ubiquitin-specific peptidase 9, X-linked in oral squamous cell carcinoma

Background

The immune checkpoint protein programmed cell death ligand 1 (PD‐L1) binds to PD1 to promote tumor cell escape from the killing effect of the immune system. However, there are few studies on the regulatory mechanisms of PD‐L1 in tumors. Although PD‐L1 has been reported to undergo ubiquitination in some cancers, its regulatory mechanisms in oral squamous cell carcinoma (OSCC) are unclear. Therefore, we aimed to investigate this phenomenon.

Methods

We examined the expression and function of USP9X and PD‐L1 in human oral keratinocytes (HOK) and OSCC cell lines (HN4 and HN30) as the control and relevant cancer cells using western blotting, immunoprecipitation, immunohistochemistry (IHC), T‐cell‐mediated tumor cell killing assay, and liquid chromatography‐mass spectrometry.

Results

Programmed cell death ligand 1 was highly expressed in OSCC by the regulation of the ubiquitin‐proteasome pathway. Furthermore, we discovered that ubiquitin‐specific peptidase 9, X‐linked (USP9X) could be combined with PD‐L1 to induce its deubiquitination and stabilize its protein expression in OSCC.

Conclusion

Our data indicate that USP9X deubiquitinates and stabilizes PD‐L1. Suppressing the expression of USP9X blocks tumor cell growth. The results provide a theoretical basis for USP9X as a therapeutic target.

EGFR-mediated signaling pathway influences the sensitivity of oral squamous cell carcinoma to JQ1

Inhibiting BRD4 has emerged as a promising anticancer strategy, and inhibitors such as JQ1 can suppress cell growth in oral squamous cell carcinoma (OSCC). However, the mechanism through which JQ1 exerts its anticancer activity has not been reported. Moreover, JQ1 does not markedly inhibit proliferation and increase apoptosis in OSCC when used as a monotherapy. Herein, we explore the mechanism of JQ1 in OSCC and probe ways to increase its therapeutic potential. In this study, we used two cell lines, Cal27, and Scc25. We found that BRD4 was highly expressed in OSCC tissues when compared with adjacent non-tumor tissues, and JQ1 worked through the EGFR-mediated signaling pathway in tumor cells. Furthermore, we demonstrated that JQ1 induced an increased treatment effect in vitro and in vivo when combined with a PI3K inhibitor. Interestingly, subsequent mechanistic analyses indicated that further suppressing EGFR and BRD4 expression was instrumental to this functional synergism. Moreover, we found that upregulating EGFR expression by EGF stimulation protected cells treated with JQ1 from apoptosis, while knockdown of EGFR before addition of JQ1 successfully mimicked the combination treatment results. In summary, our findings revealed that JQ1 can act by inhibiting the EGFR-mediated signaling pathway, and EGFR expression influences the sensitivity of OSCC to JQ1. Regarding clinical use, this study demonstrates that BRD4 is a novel therapeutic target and EGFR can be used as a biomarker to identify the most appropriate anti-BRD4 treatment strategy in OSCC.

Identification and validation long non-coding RNAs of oral squamous cell carcinoma by bioinformatics method

Gene markers of oral squamous cell carcinoma (OSCC) have great significance on early diagnosis and treatment of clinical oral cancer. In this study, we used RNA-Seq data from OSCC patients and filtered differentially-expressed long non-coding RNA (lncRNA) to further clarify the molecular mechanism. Firstly, we downloaded datasets of OSCC from National Center for Biotechnology Information(NCBI), which were predicted and analyzed by cufflinks and tophat. Then, differentially expressed lncRNA enrichment was performed with The Database for Annotation, Visualization and Integrated Discovery (DAVID). Finally, we verified the gene expression via in vitro assays. Results showed that 52 lncRNAs were significantly differentially expressed compared to those in normal oral tissues, three highly expressed genes (XLOC_002599, XLOC_002634 and XLOC_132858) were verified by RT-PCR, which was consistent with the prediction. XLOC_002634 (GAS5) transcript levels were reduced both in vivo and in vitro assays, which confirmed that the expression of GAS5 was comparatively low in OSCC. Over-expression of GAS5 in cancer cells inhibited cell proliferation. Moreover, the migration and invasion potential of cancer cells were inhibited compared to control groups. All in all, the study indicated that the decrease in GAS5 expression may contribute to OSCC tumor pathogenesis and serve as a potential target for cancer therapy.

Hypoxia induces TFE3 expression in head and neck squamous cell carcinoma

To assess the role of transcription factor μE3 (TFE3) in the tumorigenesis of head and neck squamous cell carcinoma (HNSCC), human HNSCC tissue arrays were investigated for TFE3 expression. Human HNSCC tissues with neoadjuvant inductive chemotherapey (docetaxel, cisplatin and fluorouracil, TPF) and mice HNSCC tissues from transgenic mice model were evaluated for TFE3 expression and the hypoxia pathway. The roles of EGF/EGFR mediated hypoxia in TFE3 nuclear expression were analyzed in vitro and in vivo. TFE3 expression was higher in human HNSCC tissues compared with that in normal oral mucosa. Moreover, high TFE3 expression was related to HIF-1α, PAI-1, and EGFR, which demonstrated the activation of the hypoxia pathway in HNSCC tissues. Furthermore, elevated TFE3 expression was observed in HNSCC after cisplatin-based chemotherapy, and high TFE3 expression may indicate poor response to TPF inductive chemotherapy. Furthermore, similar changes with increased TFE3 were observed in HNSCC of the transgenic mouse HNSCC model. Hypoxic culture in the human HNSCC cell line increased TFE3 expression, which promoted cell survival under hypoxia. EGFR inhibiton by cetuximab could attenuate hypoxia-induced TFE3 in the HNSCC cell line and transgenic mouse HNSCC model. These findings indicated that TFE3 was an important hypoxia-induced transcriptional factor in HNSCC. TFE3 could be regarded as a durgable therapeutic oncotarget by EGFR inhibition.

Blockade of adenosine A2A receptor enhances CD8+ T cells response and decreases regulatory T cells in head and neck squamous cell carcinoma

BACKGROUND

Cancer immunotherapy offers a promising approach in cancer treatment. The adenosine A2A receptor (A2AR) could protect cancerous tissues from immune clearance via inhibiting T cells response. To date, the role of A2AR in head and neck squamous cell carcinoma (HNSCC) has not been investigated. Here, we sought to explore the expression and immunotherapeutic value of A2AR blockade in HNSCC.

METHODS

The expression of A2AR was evaluated by immunostaining in 43 normal mucosae, 48 dysplasia and 165 primary HNSCC tissues. The immunotherapeutic value of A2AR blockade was assessed in vivo in genetically defined immunocompetent HNSCC mouse model.

RESULTS

Immunostaining of HNSCC tissue samples revealed that increased expression of A2AR on tumor infiltrating immune cells correlated with advanced pathological grade, larger tumor size and positive lymph node status. Elevated A2AR expression was also detected in recurrent HNSCC and HNSCC tissues with induction chemotherapy. The expression of A2AR was found to be significantly correlated with HIF-1α, CD73, CD8 and Foxp3. Furthermore, the increased population of CD4⁺Foxp3⁺ regulatory T cells (Tregs), which partially expressed A2AR, was observed in an immunocompetent mouse model that spontaneously develops HNSCC. Pharmacological blockade of A2AR by SCH58261 delayed the tumor growth in the HNSCC mouse model. Meanwhile, A2AR blockade significantly reduced the population of CD4⁺ Foxp3⁺ Tregs and enhanced the anti-tumor response of CD8⁺ T cells.

CONCLUSIONS

These results offer a preclinical proof for the administration of A2AR inhibitor on prophylactic experimental therapy of HNSCC and suggest that A2AR blockade can be a potential novel strategy for HNSCC immunotherapy.

Clinical and prognostic significance of HIF-1α overexpression in oral squamous cell carcinoma: a meta-analysis

BACKGROUND

Recent studies have indicated an association between hypoxia inducible factor-1 alpha (HIF-1α) expression and poor prognosis in patients with oral squamous cell carcinoma (OSCC); however, definitive evidence of this association is yet to be obtained. We performed a meta-analysis to evaluate the association of HIF-1α expression with clinicopathological characteristics and overall survival (OS) of patients with OSCC.

METHODS

A literature search for relevant studies published in English language as of February 05, 2016, was performed on PubMed, Web of Science, and EMBASE databases. Eighteen studies with a combined study population of 1474 patients with OSCC are included in the meta-analysis. Odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) was calculated using random-effects model or fixed-effects model.

RESULTS

HIF-1α overexpression was significantly associated with larger tumor size (OR = 2.28, 95% CI = 1.49-3.50, P = 0.017), advanced TNM stage (OR = 2.29, 95% CI = 1.50-3.49, P = 0.158), and lymph node metastasis (OR = 2.05, 95% CI = 1.19-3.53, P < 0.001), but not with poor differentiation (OR = 1.21, 95% CI = 0.55-2.64, P = 0.024). These results demonstrated an association between HIF-1α expression and biological behavior of OSCC. On pooled analyses, high expression of HIF-1α was associated with worse OS (HR = 1.70, 95% CI = 1.10-2.61, P < 0.001). On subgroup analyses, overexpression of HIF-1α was significantly associated with poor prognosis in Asian population (HR = 2.33, 95% CI = 1.72-3.15, P = 0.862).

CONCLUSIONS

Our findings demonstrate an association of HIF-1α overexpression with tumor size, tumor stage, lymph node metastasis, and overall survival. HIF-1α could be an independent prognostic marker in patients with OSCC.

Analysis of GLUT-1, GLUT-3, and angiogenic index in syndromic and non-syndromic keratocystic odontogenic tumors

The aim of this study was to evaluate the immunoexpression of glucose transporters 1 (GLUT-1) and 3 (GLUT-3) in keratocystic odontogenic tumors associated with Gorlin syndrome (SKOTs) and non-syndromic keratocystic odontogenic tumors (NSKOTs), and to establish correlations with the angiogenic index. Seventeen primary NSKOTs, seven recurrent NSKOTs, and 17 SKOTs were selected for the study. The percentage of immunopositive cells for GLUT-1 and GLUT-3 in the epithelial component of the tumors was assessed. The angiogenic index was determined by microvessel count. The results were analyzed statistically using the nonparametric Kruskal-Wallis test and Spearman's correlation test. High epithelial immunoexpression of GLUT-1 was observed in most tumors (p = 0.360). There was a higher frequency of negative cases for GLUT-3 in all groups. The few GLUT-3-positive tumors exhibited low expression of this protein in epithelial cells. No significant difference in the angiogenic index was observed between groups (p = 0.778). GLUT-1 expression did not correlate significantly with the angiogenic index (p > 0.05). The results suggest that the more aggressive biological behavior of SKOTs when compared to NSKOTs may not be related to GLUT-1 or GLUT-3 expression. GLUT-1 may play an important role in glucose uptake by epithelial cells of KOTs and this process is unlikely related to the angiogenic index. GLUT-1 could be a potential target for future development of therapeutic strategies for KOTs.

The role of hypoxia-inducible factors in tumor angiogenesis and cell metabolism

Hypoxia-inducible factor (HIF) is a main heterodimeric transcription factor that regulates the cellular adaptive response to hypoxia by stimulating the transcription of a series of hypoxia-inducible genes. HIF is frequently upregulated in solid tumors, and the overexpression of HIF can promote tumor progression or aggressiveness by blood vessel architecture and altering cellular metabolism. In this review, we focused on the pivotal role of HIF in tumor angiogenesis and energy metabolism. Furthermore, we also emphasized the possibility of HIF pathway as a potential therapeutic target in cancer.

Preparation of GST Inhibitor Nanoparticle Drug Delivery System and Its Reversal Effect on the Multidrug Resistance in Oral Carcinoma

During the chemotherapy of cancer, drug resistance is the first issue that chemotherapeutic drugs cannot be effectively used for the treatment of cancers repeatedly for a long term, and the main reason for this is that tumor cell detoxification is mediated by GSH (glutathione) catalyzed by GST (glutathione-S-transferase). In this study, a GST inhibitor, ethacrynic acid (ECA), was designed to be coupled with methoxy poly(ethylene glycol)-poly(lactide) (MPEG-PLA) by disulfide bonds to prepare methoxy poly(ethylene glycol)-poly(lactide)-disulphide bond-mthacrynic acid (MPEG-PLA-SS-ECA) as a carrier material of the nanoparticles. Nanoparticles of pingyangmycin (PYM) and carboplatin (CBP) were prepared, respectively, and their physicochemical properties were investigated. The ECA at the disulfide could be released in the presence of GSH, the pingyangmycin, carboplatin and ECA were all uniformly released, and the nanoparticles could release all the drugs completely within 10 days. The half maximal inhibitory concentration (IC₅₀₎ of the prepared MPEG-PLA-SS-ECA/CBP and MPEG-PLA-SS-ECA/PYM nanoparticles in drug-resistant oral squamous cell carcinoma cell lines SCC15/CBP and SCC15/PYM cells was 12.68 μg·mL^-¹ and 12.76 μg·mL^-¹, respectively; the resistant factor RF of them in the drug-resistant cells were 1.51 and 1.24, respectively, indicating that MPEG-PLA-SS-ECA nanoparticles can reverse the drug resistance of these two drug-resistant cells.

Associations among pretreatment tumor necrosis and the expression of HIF-1α and PD-L1 in advanced oral squamous cell carcinoma and the prognostic impact thereof

OBJECTIVE

The treatment strategies for advanced oral squamous cell carcinoma (OSCC), especially with necrotic changes, are not effective. The programmed death ligand 1 (PD-L1) immune escape may be one of the underlying sources of resistance. Furthermore, anti-PD-L1 directed immunotherapy may be another choice for adjuvant therapy. Therefore, the expression of PD-L1 in advanced OSCC with necrotic changes is very important.

MATERIALS AND METHODS

A total of 218 eligible patients with advanced stage (stage III/IV) OSCC and neck metastasis were enrolled. The presence of necrosis was reviewed by pretreatment magnetic resonance imaging. Paired paraffin-embedded primary tumor and metastatic lymph nodes (LN) sections were stained with antibodies against hypoxia-inducible factor-1α (HIF-1α) and PD-L1. Moderate-to strong HIF-1α nuclear staining in >10% and cell surface PD-L1 expression in >5% of OSCC cells were recorded as a positive result.

RESULTS

For advanced OSCC with necrotic changes, there was substantial agreement in primary tumor (kappa value 0.54) and almost perfect agreement in metastatic LN (kappa value 0.86) between HIF-1α and PD-L1 expression. The patients with both necrosis and positive PD-L1 expression in OSCC surrounding necrosis had worse disease control and survival outcomes. After multivariate analysis, metastatic LN necrosis and positive PD-L1 expression were found to be significant independent adverse factors.

CONCLUSION

Advanced OSCC patients with both necrosis and positive PD-L1 expression in OSCC surrounding necrosis had worse outcome. The aggressive behavior of advanced OSCC could be partially related to PD-L1 immune escape. These patients may be good candidates for anti-PD-L1 immunotherapy.

Apoptosis resistance-related ABCB5 and DNaseX (Apo10) expression in oral carcinogenesis

BACKGROUND

Apoptosis resistance is a crucial factor for the carcinogenesis of oral squamous cell carcinoma (OSCC).

METHODS

Expression of apoptosis resistance-related ATP-binding cassette (ABC) transporter ABCB5 [subfamily B (MDR/TAP) member 5] and DNaseX (Apo10) were analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I-III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry.

RESULTS

Expression of ABCB5 and Apo10 were significantly increased in the carcinogenesis of OSCC compared with normal tissue. Compared with SIN I-III, ABCB5 expression was significantly decreased in OSCC. Apo10 expression did not significantly differ from OSCC compared with SIN I-III.

CONCLUSIONS

This study provides the first evidence of the expression of ABCB5 and Apo10 in the multi-step carcinogenesis of OSCC. Overcoming drug resistance of ABCB5+ and Apo10+ cells in precursor lesions and tumors by natural compounds may act as sensitizers for apoptosis or could be useful for chemoprevention.

ErbB3 upregulation by the HNSCC 3D microenvironment modulates cell survival and growth

Head and neck squamous carcinomas (HNSCC) present as dense epithelioid three-dimensional (3D) tumor nests that can mediate signals via the human epidermal growth factor receptor (ErbB) tyrosine kinase family to promote intratumoral survival and growth. We examined the role of the tumor microenvironment on ErbB receptor family expression and found that the status of intercellular organization altered the receptor profile. We showed that HNSCC cells forced into tumor island-like 3D aggregates strongly upregulated ErbB3 at the level of transcription. Not only was the elevated ErbB3 responsive to HRG-β1-induced enhanced signaling mechanism, but also analysis by siRNA-knockdown and kinase inhibitor strategies revealed that the ErbB3/AKT signaling pathway was sufficient to enhance tumor cell survival and growth potential. Elevated ErbB3 expression in the high-density 3D culture system was strongly associated with hypoxia-induced HIF-1α. Hypoxia-regulated ErbB3 expression was mediated by the HIF-1α-binding consensus sequence in the ErbB3 proximal promoter. The findings show that the local 3D tumor microenvironment can trigger reprograming and switching of ErbB family members and thereby influence ErbB3-driven tumor growth.

Distribution of Hypoxia-Inducible Factor-1α and Glucose Transporter-1 in Human Tongue Cancers

PURPOSE

Oral squamous cell carcinomas have the potential for rapid and unlimited growth. Therefore, hypoxic tissue areas are common in these malignant tumors and contribute to cancer progression, therapy resistance, and poor outcomes. The aim of the present study was to analyze the gene product distribution of hypoxia-inducible factor-1α (HIF-1α) and glucose transporter-1 (GLUT-1) in cases of tongue squamous cell carcinoma (TSCC) and to identify a preliminary correlation between these proteins and clinical staging and Brynes's histologic grading system (HGS).

MATERIALS AND METHODS

The sample included 57 cases of TSCC. Histologic sections of 3 μm were submitted to the immunoperoxidase method and semiquantitative analysis. The association between HIF-1α and GLUT-1 expression in TSCC and the clinical stage and the HGS of Bryne (1998) was evaluated using the χ(2) test, with the significance level set at 0.05 (α = 0.05).

RESULTS

HIF-1α was mainly expressed in the nucleus/cytoplasm of neoplastic cells, most specimens exhibited diffuse staining in neoplastic cells (84.2%), and focal staining was only observed in perinecrotic areas (15.8%). GLUT-1 was expressed in the cytoplasm and membrane of malignant cells, and diffuse staining was observed in all cases. The intensity of HIF-1α expression correlated significantly with clinical stage (P = .011) and HGS (P = .002). A significant association was observed between the distribution of HIF-1α expression and metastasis (P = .040). Immunoexpression of GLUT-1 correlated significantly with clinical stage (P = .002) and HGS (P = .000). GLUT-1 expression in the peripheral island was predominant in most low-grade tumors (78.6%); in the high-grade cases, the expression prevailed in the location center/periphery (55.8%). Comparison of the location of the tumor island in the different histologic grades showed a statistically significant difference (P = .025).

CONCLUSION

The expression of HIF and GLUT proteins within TSCC appears to be associated with disease stage, grade, and the presence of metastases. Additional studies are needed to evaluate the diagnostic and prognostic uses of these proteins in the treatment of TSCC.

Serum vitamin D levels of patients with oral squamous cell carcinoma (OSCC) and expression of vitamin D receptor in oral precancerous lesions and OSCC

Background: Resistance to programmed cell death (apoptosis) is a crucial factor for the carcinogenesis of oral squamous cell carcinoma (OSCC). Vitamin D (calcitriol) may overcome apoptosis resistance in tumor cells of OSCC. Vitamin D receptor (VDR) expression in oral precancerous lesions of OSCC has not been analyzed and serum vitamin D level seems to be a predictor of cancer development. Material and Methods: Expression of VDR was analyzed in normal oral mucosa (n=5), oral precursor lesions (simple hyperplasia, n=11; squamous intraepithelial neoplasia, SIN I-III, n=35), and OSCC specimen (n=42) by immunohistochemistry (IHC). Moreover, serum vitamin D levels were measured by 25(OH)D3 (calcidiol) in patients with OSCC (n=42) and correlated with IHC results. Results: Expression of VDR was significantly increased in precancerous and OSCC compared with normal tissue. Compared with SIN I-III lesions VDR expression significantly decreased in OSCC. Severe vitamin D deficiency was detected in our OSCC patient cohort but there was no significant correlation analyzed between serum vitamin D levels and corresponding immunohistochemically detected VDR expression in OSCC. Conclusions: Our survey provides the first evidence of VDR expression in precancerous lesions of OSCC. Apoptosis induction of VDR+ cells in oral precancerous lesions and OSCC by natural vitamin D or synthetic vitamin D compounds could be useful for chemoprevention. Moreover, systemically and/or locally applied, these compounds may act as sensitizers for apoptosis mediated by radio-, and chemotherapy treatment in OSCC.

Key words:Oral cancer, oral precancer, lichen planus, leukoplakia, apoptosis, serum 25(OH)D3, vitamin D receptor, chemoprevention, multistep carcinogenesis.

Glutaminolysis and carcinogenesis of oral squamous cell carcinoma

Glutaminolysis is a crucial factor for tumor metabolism in the carcinogenesis of several tumors but has not been clarified for oral squamous cell carcinoma (OSCC) yet. Expression of glutaminolysis-related solute carrier family 1, member 5 (SLC1A5)/neutral amino acid transporter (ASCT2), glutaminase (GLS), and glutamate dehydrogenase (GLDH) was analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I-III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry. SLC1A5/ASCT2 and GLS were significantly overexpressed in the carcinogenesis of OSCC compared with normal tissue, while GLDH was weakly detected. Compared with SIN I-III SLC1A5/ASCT2 and GLS expression were significantly increased in OSCC. GLDH expression did not significantly differ from SIN I-III compared with OSCC. This study shows the first evidence of glutaminolysis-related SLC1A5/ASCT2, GLS, and GLDH expression in OSCC. The very weak GLDH expression indicates that glutamine metabolism is rather related to nucleotide or protein/hexosamine biosynthesis or to the function as an antioxidant (glutathione) than to energy production or generation of lactate through entering the tricarboxylic acid cycle. Overcoming glutaminolysis by targeting c-Myc oncogene (e.g. by natural compounds) and thereby cross-activation of mammalian target of rapamycin complex 1 or SLC1A5/ASCT2, GLS inhibitors may be a useful strategy to sensitize cancer cells to common OSCC cancer therapies.

Proton channels and exchangers in cancer

Although cancer is characterized by an intratumoral genetic heterogeneity, a totally deranged pH control is a common feature of most cancer histotypes. Major determinants of aberrant pH gradient in cancer are proton exchangers and transporters, including V-ATPase, Na+/H+ exchanger (NHE), monocarboxylate transporters (MCTs) and carbonic anhydrases (CAs). Thanks to the activity of these proton transporters and exchangers, cancer becomes isolated and/or protected not only from the body reaction against the growing tumor, but also from the vast majority of drugs that when protonated into the acidic tumor microenvironment do not enter into cancer cells. Proton transporters and exchangers represent a key feature tumor cells use to survive in the very hostile microenvironmental conditions that they create and maintain. Detoxifying mechanisms may thus represent both a key survival option and a selection outcome for cells that behave as unicellular microorganisms rather than belonging to an organ, compartment or body. It is, in fact, typical of malignant tumors that, after a clinically measurable yet transient initial response to a therapy, resistant tumor clones emerge and proliferate, thus bursting a more malignant behavior and rapid tumor progression. This review critically presents the background of a novel and efficient approach that aims to fight cancer through blocking or inhibiting well characterized proton exchangers and transporters active in human cancer cells. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

The use of CA-IX as a diagnostic method for oral leukoplakia

The presence and degree of dysplasia are important diagnostic and prognostic criteria for oral leukoplakia, but evaluation of dysplasia is difficult and subjective. Carbonic anhydrase-IX (CA-IX) is expressed primarily in tumor cells and is considered a specific hypoxia marker. We investigated the role of CA-IX in oral leukoplakia. We investigated 30 specimens of oral leukoplakia and 35 dysplasia specimens adjacent to the tumor margin. We analyzed clinical variables including age, sex, degree of dysplasia, and smoking, clinical appearance of leukoplakia, number of lesions, location, size, clinical monitoring, malignant transformation and recurrence. For the immunohistochemical study, we used a noncommercial monoclonal antibody against human CA-IX MAb M75. We found greater CA-IX positivity in nonsmokers, erythroplakia and mottled leukoplakia, those located on the tongue, patients with multiple lesions, 2-4 cm leukoplakias and in recurrent cases, although differences were not statistically significant. All lesions in all samples without dysplasia were negative for CA-IX; however, for all other categories of dysplasia, the percentages of positivity and negativity varied. Regarding the diagnostic index values, we found a sensitivity of 32%, specificity of 100%, a positive predictive value of 100% and a negative predictive value of 13%. Leukoplakias appear mainly in females and potentially are malignant; more than 90% have some degree of dysplasia, and therefore require close clinical and histopathological monitoring. The CA-IX immunohistochemical marker may be useful for screening samples without dysplasia owing to its high specificity.

Expression of Glucose Transporters 1 and 3 in Metastatic and Non-Metastatic Lower Lip Squamous Cell Carcinoma

This study aimed to evaluate the immunoexpression of glucose transporters 1 (GLUT-1) and 3 (GLUT-3) in metastatic and non-metastatic lower lip squamous cell carcinoma (LLSCC). Twenty LLSCCs with regional nodal metastasis and 20 LLSCCs without metastasis were selected. The distribution of staining and the percentage of GLUT-1 and GLUT-3 staining in each tumor core and at the deep invasive front were assessed. Most tumors (70%) exhibited peripheral staining for GLUT-1 in nests, sheets and islands of neoplastic cells, whereas predominantly central staining was observed for GLUT-3 (72.5%). A high percentage of GLUT-1-positive cells was observed at the deep invasive front and in the tumor core of metastatic and non-metastatic tumors (p>0.05). The percentage of GLUT-1-positive cells was much higher than that of GLUT-3-positive cells both in the deep invasive front (p<0.001) and in the tumor core (p<0.001) of LLSCCs. No significant differences in the percentage of GLUT-1- and GLUT-3-positive cells were observed according to nodal metastasis, clinical stage or histological grade of malignancy (p>0.05). In conclusion, the results of the present study suggest an important role of GLUT-1 in glucose uptake in LLSCCs, although this protein does not seem to be involved in the progression of these tumors. On the other hand, GLUT-3 expression may represent a secondary glucose uptake mechanism in LLSCCs.

2-Deoxy-D-glucose targeting of glucose metabolism in cancer cells as a potential therapy

Cancer cells are characterized by altered glucose metabolism known as the Warburg effect in which aerobic glycolysis is increased. Glucose is converted to lactate even under sufficient oxygen tension. Interfering with this process may be a potential effective strategy to cause cancer cell death because these cells rely heavily on glucose metabolism for survival and proliferation. 2-Deoxy-D-glucose (2DG), a glucose analog, targets glucose metabolism to deplete cancer cells of energy. In addition, 2DG increases oxidative stress, inhibits N-linked glycosylation, and induces autophagy. It can efficiently slow cell growth and potently facilitate apoptosis in specific cancer cells. Although 2DG itself has limited therapeutic effect in many types of cancers, it may be combined with other therapeutic agents or radiotherapy to exhibit a synergistic anticancer effect. In this review, we describe the Warburg effect and discuss 2DG and its underlying mechanisms and potential application for cancer treatment.

Association of cancer metabolism-related proteins with oral carcinogenesis - indications for chemoprevention and metabolic sensitizing of oral squamous cell carcinoma?

Background

Tumor metabolism is a crucial factor for the carcinogenesis of oral squamous cell carcinoma (OSCC).

Methods

Expression of IGF-R1, glycolysis-related proteins (GLUT-1, HK 2, PFK-1, LDHA, TKTL1), mitochondrial enzymes (SDHA, SDHB, ATP synthase) were analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I-III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry and real-time polymerase chain reaction (qPCR) analysis in OSCC cell lines. Metabolism-related proteins were correlated with proliferation activity (Ki-67) and apoptotic properties (TUNEL assay) in OSCC. Specificity of antibodies was confirmed by western blotting in cancer cell lines.

Results

Expression of IGF-R1, glycolysis-related proteins (GLUT-1, HK 2, LDHA, TKTL1), and mitochondrial enzymes (SDHA, SDHB, ATP synthase) were significantly increased in the carcinogenesis of OSCC. Metabolic active regions of OSCC were strongly correlated with proliferating cancer (Ki-67+) cells without detection of apoptosis (TUNEL assay).

Conclusions

This study provides the first evidence of the expression of IGF-R1, glycolysis-related proteins GLUT-1, HK 2, PFK-1, LDHA, and TKTL1, as well as mitochondrial enzymes SDHA, SDHB, and ATP synthase in the multi-step carcinogenesis of OSCC. Both, hypoxia-related glucose metabolism and mitochondrial oxidative phosphorylation characteristics are associated with the carcinogenesis of OSCC. Acidosis and OXPHOS may drive a metabolic shift towards the pentose phosphate pathway (PPP). Therefore, inhibition of the PPP, glycolysis, and targeted anti-mitochondrial therapies (ROS generation) by natural compounds or synthetic vitamin derivatives may act as sensitizer for apoptosis in cancer cells mediated by adjuvant therapies in OSCC.

Transcutaneous carbon dioxide induces mitochondrial apoptosis and suppresses metastasis of oral squamous cell carcinoma in vivo

Squamous cell carcinoma (SCC) is the main histological type of oral cancer. Its growth rate and incidence of metastasis to regional lymph nodes is influenced by various factors, including hypoxic conditions. We have previously reported that transcutaneous CO₂ induces mitochondrial apoptosis and decreases lung metastasis by reoxygenating sarcoma cells. However, previous studies have not determined the sequential mechanism by which transcutaneous CO₂ suppresses growth of epithelial tumors, including SCCs. Moreover, there is no report that transcutaneous CO₂ suppresses lymphogenous metastasis using human cell lines xenografts. In this study, we examined the effects of transcutaneous CO₂ on cancer apoptosis and lymphogenous metastasis using human SCC xenografts. Our results showed that transcutaneous CO₂ affects expressions of PGC-1α and TFAM and protein levels of cleavage products of caspase-3, caspase-9 and PARP, which relatives mitochondrial apoptosis. They also showed that transcutaneous CO₂ significantly inhibits SCC tumor growth and affects expressions of HIF-1α, VEGF, MMP-2 and MMP-9, which play essential roles in tumor angiogenesis, invasion and metastasis. In conclusion, transcutaneous CO₂ suppressed tumor growth, increased mitochondrial apoptosis and decreased the number of lymph node metastasis in human SCC by decreasing intra-tumoral hypoxia and suppressing metastatic potential with no observable effect in vivo. Our findings indicate that transcutaneous CO₂ could be a novel therapeutic tool for treating human SCC.

Risk prediction for malignant conversion of oral epithelial dysplasia by hypoxia related protein expression

AIMS

Increased aerobic glycolysis is a unique finding in cancers and hypoxia-related proteins are associated with aerobic glycolysis. Therefore, we aimed to investigate whether hypoxia-related proteins can be predictive markers for malignant conversion of oral premalignant lesions with epithelial dysplasia (OED).

METHODS

Expression of HIF-1α, Glut-1 and CA9 were detected in clinical samples of eight normal oral mucosa, 85 transitional areas of oral squamous cell carcinoma (OSCC) and 28 OED with or without malignant conversion using immunohistochemistry and were also comparatively detected in immortalised human oral keratinocyte (IHOK) and OSCC cell lines under hypoxia using immunoblotting.

RESULTS

Sequential expression of HIF-1α, Glut-1 and CA9 was found both in transitional areas of OSCC and cell lines of IHOK and OSCC under hypoxia, supporting hypoxia-aerobic glycolysis-acidosis axis. Expression of all proteins showed significant association with malignant conversion of OED and CA9 was an independent risk factor of malignant transformation of OED. But the predictability of malignant transformation was improved when all three proteins were applied together.

CONCLUSION

High expression of CA9 was an independent predictive marker of malignant conversion. Moreover, the combined application of these three proteins may be useful to assess the risk of malignant conversion of OED.

GLUT-1(+)/TKTL1(+) coexpression predicts poor outcome in oral squamous cell carcinoma

OBJECTIVE

Tumor hypoxia is a crucial negative prognostic factor associated with outcome of oral squamous cell carcinoma (OSCC).

STUDY DESIGN

Expression of glucose transporter 1 (GLUT-1) (solute carrier family 2 [facilitated glucose transporter], member 1 [SLC2A1]) was analyzed in OSCC specimen (n = 161) and cancer cell lines by immunohistochemistry and Western blotting. GLUT-1 expression on protein level was correlated with transketolase-like 1 (TKTL1) expression, clinical characteristics, and effect on survival. Subgroup analysis was performed for GLUT-1/TKTL1 coexpression.

RESULTS

GLUT-1 expression was significantly correlated with TKTL1 expression (P < .0001) and recurrence of the tumor (P = .001). Multivariate analysis did not find GLUT-1 expression to be an independent prognostic factor (P = .2478). GLUT-1(+)/TKTL1(+) subgroup showed the worst effect on survival compared with the GLUT-1(-)/TKTL1(-) subgroup (P = .0002).

CONCLUSIONS

This study provides evidence that tumors linked with combined enhanced glucose uptake (GLUT-1(+)) and hypoxia-related glucose metabolism (TKTL1(+)) characteristics (GLUT-1(+)/TKTL1(+) coexpression) are associated with shorter survival in OSCC.

Prognostic impact of cigarette smoking on the survival of patients with established nasopharyngeal carcinoma

BACKGROUND

Cigarette smoking is associated with the etiology of nasopharyngeal carcinoma; however, the influence of smoking on survival in patients with established nasopharyngeal carcinoma remains unknown.

METHODS

We retrospectively analyzed 1,849 patients with nasopharyngeal carcinoma who were categorized as never, former, and current smokers. Cumulative effect of smoking was defined in terms of pack-years. Associations between cigarette exposure and survival were estimated by Cox proportional hazards model.

RESULTS

The risks of death, progression, locoregional relapse, and distant metastasis were significantly higher for former and current smokers (all P ≤ 0.002) than never smokers. Heavy smokers with high pack-years had HRs for death of 3.31 [95% confidence interval (CI), 2.58-4.26; P < 0.001], for progression of 2.53 (95% CI, 2.03-3.16; P < 0.001), and for distant metastasis of 2.65 (95% CI, 1.89-3.70; P < 0.001). Specifically, in the cohort of 495 patients treated with intensity-modulated radiotherapy/three-dimensional conformal radiotherapy, we obtained similarly significant results. All of the survival outcomes remained significant in multivariate analyses.

CONCLUSIONS

Pretreatment cigarette smoking is an independent, poor prognostic factor for patients with nasopharyngeal carcinoma, which is associated with increased risk of death, progression, locoregional relapse, and distant metastasis, with the risk increasing with pack-years.

IMPACT

It is clear that cigarette smoking not only promotes carcinogenesis in the normal nasopharyngeal epithelium, but also affects the survival of patients with nasopharyngeal carcinoma.

Oxygen metabolism in oral cancer: HIF and GLUTs (Review)

Oral cancer is a significant cause of morbidity and mortality, and has a poor prognosis. This has encouraged additional studies into factors that may affect the development of this disease. The biological behavior of malignant neoplasms is complex. Studies have investigated the energy metabolism of tumor cells, in an endeavor to elucidate the tumor biology. The identification of molecular signatures and mechanisms, in order to understand tumor progression, may facilitate the identification of novel predictive and prognostic markers. Pathways that influence tumor progression, such as those involving hypoxia-inducible factor (HIF) and glucose transporter (GLUT) proteins, have been the targets of recent studies.