[Molecular basis of ameloblastoma pathogenesis: A review]

Ameloblastoma is the most common and highly invasive benign odontogenic tumor. Its pathogenesis is not yet fully understood.

Objective

To describe the most important molecular findings that promote the proliferative activity of ameloblastoma and the factors involved that encourage invasion into surrounding bone tissues.

Methodology

A search for scientific evidence was conducted through the following databases: Science Direct, Medline, Wiley, Web of Science, and Google Scholar. A total of 32 articles were reviewed, with inclusion criteria being articles published in English and Spanish; descriptive and analytical studies, narrative and systematic reviews published from January 2015 to June 2021. Letters to the editor were excluded.

Results

The biological molecular findings that allow ameloblastoma to invade surrounding tissues involve alterations in the RANK/RANKL/OPG pathways, transforming growth factor beta (TGF-β), Wnt/β-catenin pathway, and matrix metalloproteinases, as well as alterations in MAPK and SHH pathways that facilitate the proliferation and tumor development of ameloblastoma.

Conclusions

These findings are fundamental for a better understanding of the pathways involved in the pathogenesis of ameloblastoma.

Biological marker for the establishment of periodontal disease: cross-sectional study in the gingival tissue

BACKGROUND

The present study investigated the expression of COX-2, EMMPRIN, HIF-1α, and GLUT-1 in the gingival tissue to verify if there is a correlation between the immunoexpression of these proteins and the changes caused by the inflamed infiltrate present in the gingival tissues.

MATERIAL AND METHODS

A morphological analysis of epithelial changes (hyperplasia, exocytosis, spongiosis, and hydropic degeneration) was performed, as well as a semiquantitative analysis of the immunoexpression of COX-2, EMMPRIN, HIF-1α, and GLUT-1 in the epithelium and connective tissue of 60 specimens of gingival tissue.

RESULTS

Epithelial immunoexpression to COX-2 was observed in three cases, while EMMPRIN, HIF-1α, and GLUT-1 were strongly expressed in the basal layer of the epithelium and gradually decreased until the upper layers. In the connective tissue, COX-2 immunoexpression showed a statistically significant association (p < 0.001) with the gingival inflammatory infiltrate. In connective tissue, EMMPRIN and HIF-1α exhibited intense immunopositivity, while GLUT-1 was negative in most cases.

CONCLUSION

COX-2 expression may constitute a biological marker of gingival tissues since its epithelial immunoexpression may indicate a greater propensity for the establishment of periodontal disease.

Study of expression of GLUT-1 in oral potentially malignant disorders and oral squamous cell carcinoma: An immuno-histochemical analysis

Background

Glucose is the chief source of energy for cells, and glucose transporter 1 (GLUT-1) is one of the most common glucose transporters in humans. Tumour cells are known to express hypoxia-related protein, and these may allow tumour cells to survive under a sustained hypoxic environment. Surviving cells develop a more aggressive phenotype, which results in poor prognosis.

Aims and Objectives

Expression and comparison of GLUT-1 in normal tissues, potentially malignant disorders (PMDs), and oral squamous cell carcinoma (OSCC) and comparison of expression in different grades of OSCC.

Material and Methods

A total of 57 cases (10 normal, 17 PMD, and 30 cases of OSCC) were stained immuno-histochemically with GLUT-1. The expression was scored as 0, 1, 2, 3, and 4 for negative, mild, moderate, severe, and intense staining, respectively.

Results

GLUT-1 expression was detected in all grades of OSCC. A significant correlation was found on comparing normal and OSCC, normal and PMDs, and PMD and OSCC. The expression of GLUT-1 was significant when compared with different histopathological grades of OSCC.

Conclusions

Expression of GLUT-1 increased from normal to PMDs to increasing grades of OSCC and hence can be used as a prognostic predictive marker for OSCC.

miRNA Associated With Glucose Transporters in Oral Squamous Cell Carcinoma: A Systematic Review

Oral squamous cell carcinoma (OSCC) is a malignancy of the oral cavity with poor prognosis. Dysregulation in glycolytic pathways involving glucose transporters (GLUT) has been implicated in poor prognosis. Furthermore, GLUT expression in cancer cells is regulated by several miRNAs. However, there is a lack of data about miRNA involved in the regulation of GLUT in OSCC. The objective is to evaluate the role of miRNA in the regulation of GLUT in OSCC. Data sources include PubMed (MEDLINE), Scopus, and Web of Science. Studies evaluating the miRNA involved or associated with the regulation of GLUT in OSCC were included in the systematic review. Data pertaining to GLUT and associated miRNA expression were extracted from studies. Qualitative assessment was carried out for GLUT and miRNA. The Newcastle-Ottawa Scale was used for quality assessment. Ten study articles were included after analyzing 4675 papers. These studies evaluated the GLUT and miRNA expression between healthy and OSCC samples. There are variable expression patterns of GLUT in OSCC. Furthermore, it was dependent on miRNA. The GLUT1 and GLUT-3 were detected more frequently in OSCC, while no study reveals the expression of GLUT2, GLUT4, GLUT7, GLUT8, GLUT13, SGLT1, and SGLT2 with miRNA regulation. However, there was insufficient evidence on specific miRNA linked to GLUT1 or GLUT3 expression. There is evidence of the role of miRNA in the regulation of GLUT especially GLUT1 and GLUT3 in OSCC; however, a specific relation to miRNA was understudied. In the future, studies exploring a clearer understanding of the association between miRNA and the GLUT metabolic pathway in relation to OSCC are warranted. Furthermore, association of miRNA and GLUT with progression of disease, disease resistance, and prognosis is assessed for better treatment outcomes.

A Comparison of Podoplanin Expression in Oral Leukoplakia and Oral Squamous Cell Carcinoma: An Immunohistochemical Study

INTRODUCTION

Oral squamous cell carcinoma (OSCC) accounts for about 90% to 95% of all malignancies of the oral cavity.The majority of OSCCs are preceded by oral potentially malignant disorders (OPMDs). Podoplanin (PDPN) is a mucin-like small transmembrane glycoprotein. Alterations in PDPN immunoexpression have been reported in OPMDs and OSCCs.

OBJECTIVE

The objectives of this study were to evaluate the role of PDPN immunoexpression in oral leukoplakia (OL) and different histological grades of OSCC and to assess the role of PDPN as a potential biomarker for predicting the risk of malignant transformation.

MATERIALS AND METHODOLOGY

Immunohistochemical analysis for PDPN was performed in 45 histologically confirmed cases of formalin-fixed, paraffin-embedded specimens of different grades of OSCCs and 15 cases of OLs with 15 cases of the normal oral mucosa (NOM) as controls. The expression and distribution of this marker were analyzed in these lesions.

RESULTS

The immunoexpression of PDPN showed a significant increase in the expression of the percentage of positive cells, staining intensity, location of staining in the epithelium, tumor islands, and within the cells, as well as the mean lymphatic micro vessel density between NOMs, OLs, and different grades of OSCCs.

CONCLUSION

Upregulation of PDPN can be related to the malignant transformation of OLs and biological aggressiveness of OSCCs. The enhanced immunoexpression of PDPN signifies that this immunomarker can have a role in tumor cell differentiation and the neoplastic progression of OSCCs. Increased density of lymphatic vessels suggested an important role of lymphangiogenesis in tumor progression and also as a prognostic factor for lymph nodal metastasis.

Oral verrucous carcinoma: a diagnostic and therapeutic challenge

BACKGROUND

Verrucous carcinoma is a low-grade variant of squamous cell carcinoma with specific morphologic, cytokinetic and clinical features. Despite low mitotic activity and slow growth, it can infiltrate adjacent tissues in advanced stages but does not metastasize. The most frequently affected site is the oral cavity. The following article provides latest updates in the etiology, clinical presentation, diagnostics and treatment options in oral verrucous carcinoma and discusses the existing dilemmas linked to this unique malignancy.

CONCLUSIONS

Oral verrucous carcinoma must be differentiated from conventional squamous cell carcinoma due to its less aggressive behaviour with a more favourable prognosis. Close communication between clinician and pathologist is mandatory for making a correct diagnosis. Primary surgery with negative surgical margins seems to be the most successful treatment. However, management recommendations are not uniform since they are mostly based on case reports and small retrospective case series. Prospective and pooled multi-institutional studies are therefore needed.

Immunoexpression profile of hypoxia-inducible factor (HIF) targets in potentially malignant and malignant oral lesions: a pilot study

Oral potentially malignant disorders (OPMD) are associated with an increased risk of oral squamous cell carcinoma (OSCC). OSCC has an aggressive profile and is the most prevalent among different head and neck malignancies. Most OSCC patients are diagnosed with advanced stage tumors and have a poor prognosis. Cancer cells are able to reprogram their metabolism, even in the presence of oxygen, enhancing the conversion of glucose to lactate via the glycolytic pathway, a phenomenon mainly regulated by hypoxia-inducible factor (HIF) signaling. Thus, several glycometabolism-related biomarkers are upregulated. This study aimed to evaluate the immunoexpression of the HIF targets GLUT1, GLUT3, HK2, PFKL, PKM2, pPDH, LDHA, MCT4, and CAIX in OPMD and OSCC samples, in order to identify potential correlations between biomarkers' immunoexpression, clinicopathological features, and prognostic parameters. OSCC and OPMD samples from 21 and 34 patients (respectively) were retrospectively collected and stained for the different biomarkers by immunohistochemistry. CAIX and MCT4 expressions were significantly higher in OSCC samples when compared with OPMD samples, while the rest were also expressed by OPMD. GLUT3 and PKM2 alone, and the concomitant expression of more than four glycometabolism-related biomarkers were significantly correlated with the presence of dysplasia in OPMD. When considering OSCC cases, a trend toward increased expression of biomarkers and poor clinicopathological features was observed, and the differences regarding HK2, PFKL, LDHA and MCT4 expression were significant. Moreover, HK2 and CAIX were correlated with low survival rates. GLUT1 and GLUT3 were significantly associated with poor outcome when their expression was observed in the hypoxic region of malignant lesions. OPMD and OSCC cells overexpress glycolysis-related proteins, which is associated with aggressive features and poor patient outcome. Further research is needed to deeply understand the glycolic phenotype in the process of oral carcinogenesis.

m6A-modified circFOXK2 targets GLUT1 to accelerate oral squamous cell carcinoma aerobic glycolysis

N⁶-methyladenosine (m⁶A) is an abundant nucleotide modification in mRNA, and its emerging roles have been gradually identified. However, the potential function of m⁶A and m⁶A-modified circular RNA (circRNA) is still unclear. Here, m⁶A-circRNA epitranscriptomic microarray analysis revealed a high-expressed m⁶A-modified circFOXK2 (hsa_circ_0000816, from FOXK2 gene) in oral squamous cell carcinoma (OSCC). For the biofunctions of OSCC, results revealed that circFOXK2 promoted the malignant phenotypes of OSCC cells. Methylated RNA immunoprecipitation sequencing (MeRIP-Seq) demonstrated that a remarkable m⁶A modified site was installed on glucose transporter 1 (GLUT1) mRNA. Mechanistically, circFOXK2 promoted the GLUT1 mRNA stability through cooperating with insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) in a m⁶A-dependent manner. In summary, the present study explored the oncogenic role of m⁶A-modified circFOXK2 in OSCC through the m⁶A-dependent IGF2BP3/GLUT1 axis, indicating a potential therapeutic target for OSCC.

Molecular Biomarkers of Malignant Transformation in Head and Neck Dysplasia

Head and neck squamous cell carcinoma (HNSCC) and its treatments are associated with substantial morbidity, often resulting in cosmetic deformity and loss of physiologic functions including speech and swallowing. Despite advancements in treatment, 5-year survival rates for mucosal malignancies remain below 70%. Effective prevention of HNSCC demands an understanding of the molecular pathways of carcinogenesis. Specifically, defining features of pre-cancerous dysplastic lesions that indicate a better or worse prognosis is necessary to help identify patients who are likely to develop a carcinoma and allow a more aggressive approach to management. There remains a need for identification of biomarkers that can provide both early prognostic and predictive value in clinical decision-making by serving as both therapeutic targets as well as predictors of therapy response. Here, we comprehensively review the most frequently altered molecular biomarkers of malignant transformation in head and neck dysplasia. These markers are involved in a wide range of cellular processes in head and neck carcinogenesis, including extracellular matrix degradation, cell motility and invasion, cell-cell adhesion, solute transport, immortalization, metabolism, the cell cycle and apoptosis, transcription, and cell signaling.

Microenvironment in Oral Potentially Malignant Disorders: Multi-Dimensional Characteristics and Mechanisms of Carcinogenesis

Oral potentially malignant disorders (OPMDs) are a group of diseases involving the oral mucosa and that have a risk of carcinogenesis. The microenvironment is closely related to carcinogenesis and cancer progression by regulating the immune response, cell metabolic activities, and mechanical characteristics. Meanwhile, there are extensive interactions between the microenvironments that remodel and provide favorable conditions for cancer initiation. However, the changes, exact roles, and interactions of microenvironments during the carcinogenesis of OPMDs have not been fully elucidated. Here, we present an updated landscape of the microenvironments in OPMDs, emphasizing the changes in the immune microenvironment, metabolic microenvironment, mechanical microenvironment, and neural microenvironment during carcinogenesis and their carcinogenic mechanisms. We then propose an immuno–metabolic–mechanical–neural interaction network to describe their close relationships. Lastly, we summarize the therapeutic strategies for targeting microenvironments, and provide an outlook on future research directions and clinical applications. This review depicts a vivid microenvironment landscape and sheds light on new strategies to prevent the carcinogenesis of OPMDs.

Impact of hyperglycemia on the expression of GLUT1 during oral carcinogenesis in rats

BACKGROUND

On the background of the epidemiological link between diabetes and oral cancer, the present study aimed to analyze the potential involvement of selected glucose transporters (GLUT1/GLUT3/GLUT4), if any, in such putative association.

METHODS AND RESULTS

Oral carcinogenesis was induced by 4-nitroquinoline N-oxide in 10 non-diabetic and 10 diabetic rats; 8 non-diabetic and 7 diabetic rats served as controls. Expressions of selected GLUTs at mRNA and protein levels were analyzed in oral tissue (normal/lesion) by quantitative real-time PCR and immunohistochemistry respectively. Premalignant lesions (hyperplasia/dysplasia/carcinoma-in-situ) appeared on tongues of carcinogen-treated animals. Significant increase of GLUT1mRNA level was seen from normal to lesion tongues, along increasing lesion grades (from hyperplasia/mild dysplasia to moderate/severe dysplasia) and in lesions induced under hyperglycemic condition than that induced under normoglycemic one; a similar trend was found in transcript variant-1 of GLUT1, but not in variant-2. GLUT3 and GLUT4 mRNA levels were comparable among lesions irrespective of grades and glycemic status. Concordant to mRNA level, overall expression of GLUT1 protein was higher in tongue lesions in presence of hyperglycemia than in absence of such condition; non-lesion portions of tongues exposed to carcinogen showed a similar trend. Moreover in carcinogen-treated groups, non-lesion and lesion portions of tongues under hyperglycemic condition showed predominantly membranous expression for GLUT1 which was again significantly higher than equivalent portions of tongue under normoglycemic condition.

CONCLUSION

Hyperglycemia seemed to favor GLUT1 over-expression and membrane localization of the protein during oral carcinogenesis. GLUT1 transcript variant-1 appeared to be more important than variant-2 in disease pathogenesis.

The Role of Glucose Transporters in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a prevalent malignancy associated with a poor prognosis. The Warburg effect can be observed in OSCCs, with tumours requiring a robust glucose supply. Glucose transporters (GLUTs) and sodium-glucose co-transporters (SGLTs) are overexpressed in multiple malignancies, and are correlated with treatment resistance, clinical factors, and poor overall survival (OS). We conducted a systematic review to evaluate the differences in GLUT/SGLT expression between OSCC and normal oral keratinocytes (NOK), as well as their role in the pathophysiology and prognosis of OSCC. A total of 85 studies were included after screening 781 papers. GLUT-1 is regularly expressed in OSCC and was found to be overexpressed in comparison to NOK, with high expression correlated to tumour stage, treatment resistance, and poor prognosis. No clear association was found between GLUT-1 and tumour grade, metastasis, and fluorodeoxyglucose (FDG) uptake. GLUT-3 was less thoroughly studied but could be detected in most samples and is generally overexpressed compared to NOK. GLUT-3 negatively correlated with overall survival (OS), but there was insufficient data for correlations with other clinical factors. Expression of GLUT-2/GLUT-4/GLUT-8/GLUT-13/SGLT-1/SGLT-2 was only evaluated in a small number of studies with no significant differences detected. GLUTs 7 and 14 have never been evaluated in OSCC. In conclusion, the data demonstrates that GLUT-1 and GLUT-3 have a role in the pathophysiology of OSCC and represent valuable biomarkers to aid OSCC diagnosis and prognostication. Other GLUTs are comparatively understudied and should be further analysed because they may hold promise to improve patient care.

Prognostic significance of hypoxia-inducible factor-1α expression in advanced pharyngeal cancer without human papillomavirus infection

OBJECTIVE

This study aimed to clarify the association between both hypoxia-inducible factor-1α and glucose transporter type-1 expression and survival outcome in advanced pharyngeal cancer without human papillomavirus infection.

METHOD

Twenty-five oropharyngeal and 55 hypopharyngeal cancer patients without human papillomavirus infection were enrolled. All patients had stage III-IV lesions and underwent concurrent chemoradiotherapy or surgery. Hypoxia-inducible factor-1α and glucose transporter type-1 expression were investigated in primary lesions by immunohistochemistry.

RESULTS

There were 41 and 39 cases with low and high hypoxia-inducible factor-1α expression, and 28 and 52 cases with low and high glucose transporter type-1 expression, respectively. There was no significant correlation between hypoxia-inducible factor-1α and glucose transporter type-1 expression. In univariate analysis, nodal metastasis, clinical stage and high hypoxia-inducible factor-1α expression, but not glucose transporter type-1 expression, predicted significantly worse prognosis. In multivariate analysis, hypoxia-inducible factor-1α overexpression was significantly correlated with poor overall survival, disease-specific survival and recurrence-free survival.

CONCLUSION

High hypoxia-inducible factor-1α expression was an independent risk factor for poor prognosis for advanced human papillomavirus-unrelated pharyngeal cancer.

Evaluation of glucose transporter-1 expression in oral epithelial dysplasia and oral squamous cell carcinoma: An immunohistochemical study

Introduction

Oral squamous cell carcinoma (OSCC) is the most common malignancy of oral cavity and is commonly preceded by oral potentially malignant disorders. Glucose transporter-1 (GLUT-1) protein expression is upregulated in malignant cells that show increased glucose uptake. Alterations in GLUT-1 expression have been reported in several potentially malignant and malignant lesions.

Aims and Objectives

The aims and objectives of this study were to analyze and assess the role of GLUT-1 immunomarker in oral epithelial dysplasia (OED) and OSCC, to demonstrate and analyze the presence, location and intensity of GLUT-1 immunomarker in low-risk and high-risk OEDs and in different grades of OSCC and to correlate the expression of GLUT-1 immunomarker between normal oral mucosa (NOM), OED and different grades of OSCC.

Materials and Methodology

A total of ninety paraffin-embedded tissue blocks, 15 each of NOM; low-risk and high-risk OED and well, moderately and poorly differentiated OSCC were stained with the immunomarker GLUT-1.

Results and Observation

GLUT-1 immunoexpression was statistically significant in terms of number of positive cells, staining intensity, IRS score and level of staining within the epithelium and also within the cell between NOM, OED and OSCC.

Conclusion

Increased GLUT-1 expression has a consistent role in the malignant transformation of OED and aggressiveness of OSCC.

Can Increased Metabolic Status be a Grading Tool for Oral Squamous Cell Carcinoma? A Glucose Transporter 1 Immunoexpression Study

Background:

Glucose transporter-1 (GLUT-1) is a GLUT protein whose expression is upregulated in malignant cells where enhanced uptake of glucose is observed.

Aim:

The aim of this study is to evaluate the expression of GLUT-1 protein in oral squamous cell carcinoma (OSCC) tissue sections using immunohistochemistry and to describe the relationship between increased metabolic status and the grades of OSCC.

Materials and Methods:

This is cross-sectional study with 76 formalin-fixed paraffin-embedded tissue blocks of OSCC, obtained from the archives of the department. All the cases were scored using Bryne's grading system by three oral pathologists independently. The tissue sections were then stained using immunohistochemistry with anti-GLUT-1 rabbit monoclonal antibody.

Results:

Staining intensity and localization of positively stained slides were evaluated. Overall, a significant correlation between Bryne's histopathological grading system for OSCC and GLUT-1 immunohistochemical expression was observed. Thus, high GLUT-1 expressions are observed with increasing grades of OSCC.

Conclusion:

This study shows that a significant positive correlation exists between GLUT-1 immunoexpression and histological grading of OSCC. Thus, GLUT-1 expression can be used as a diagnostic adjunct and prognostic marker for OSCC patients.

CD147 promotes glucose metabolism, invasion and metastasis via PI3K/AKT pathway in oral squamous cell carcinomas

Background

The incidence of oral cancers, especially that of oral squamous cell carcinoma (OSCC), has increased significantly in the last few decades. Aggressive tumor progression and metastasis are the key factors responsible for the high mortality rate associated with OSCC. CD147 is known to play a key role in tumor metastasis and is associated with poor prognosis in oral cancer. It is also a crucial regulator of glucose metabolism in cancer cells. The aim of this study was to determine the effect of CD147 on OSCC invasiveness, metastasis and glucose metabolism, as well as the underlying mechanism.

Methods

CD147 was knocked down in the human OSCC lines SCC-25 and CAL-27, and both the wild-type and knockdown cells were then stably transfected with PI3K cDNA. Glucose metabolism and in vitro migration of the OSCC cells were respectively analyzed by glucose uptake and lactate secretion assays, and transwell assay.

Results

Knocking down CD147 in the OSCC cells significantly reduced their migration, and decreased glucose metabolism. The inhibitory effects of blocking CD147 were reversed upon PI3K overexpression.

Conclusions

CD147 mediates its oncogenic effects via the PI3K/AKT pathway, and is a potential prognostic factor and therapeutic target for OSCC.

Glucose metabolism changes during the development and progression of oral tongue squamous cell carcinomas

Previous studies have revealed several genes involved in the carcinogenesis of oral cancer. However, the detailed mechanisms underlying this process are poorly understood. Previously, we established a database cataloging the transcriptional progression profile of oral carcinogenesis and identified several candidate genes with continuously increasing or decreasing expression, which specifically promote the transition of oral premalignant lesions to invasive carcinomas. In this study, using our microarray database, we attempted to determine significant genes that may contribute to metabolic alterations during oral carcinogenesis. After performing a literature survey, we focused on 15 candidate genes associated with glucose metabolism changes, particularly the tri-carboxylic acid cycle, and investigated the mRNA-expression status of these genes with our database. Only the solute carrier family 2 member 1 gene (also known as GLUT1), showed significantly increased mRNA expression during oral tumorigenesis. Immunohistochemical analysis confirmed that GLUT1 protein expression significantly increased during oral carcinogenesis. In addition, tumors with high expression of this protein significantly correlated with nodal status (P=0.002). Kaplan-Meier survival curves clearly demonstrated the adverse impact of high GLUT1 protein expression on disease-free survival (P=0.004). GLUT1 mRNA and protein expression increased in the order of normal mucosal tissues, epithelial dysplastic lesions and invasive carcinomas. Therefore, metabolic alterations, especially in glucose metabolism, occurred at the very early stage of development of oral malignancies. In addition, GLUT1 played a significant role in oral cancer, acquiring a malignant phenotype.

Glucose transporter 1 in health and disease

Glucose, a major source of energy for all cells, is transported into cells with the help of glucose transporters (GLUTs). These transporters are of two types, namely sodium-dependent GLUTs and facilitative GLUTs. These transporters are present in a tissue-specific pattern and have substrate specificity. Among these transporters, GLUT1 (facilitative GLUT) is present ubiquitously on all tissues of the body and helps in the basal uptake of glucose. GLUT1 is known to have many physiological functions in the body from the time of implantation of an embryo and is also seen associated with pathologies, including cancers. This review mainly focuses on GLUT1 in physiological and pathological conditions and the recent advances related to its role in cancer development and applications in cancer therapeutics.

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.

Glucose Transporter 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study

INTRODUCTION

An array of odontogenic lesions manifest in the maxillofacial region with variable presentations. The biological behavior of lesions, such as odontogenic keratocyst (OKC), dentigerous cyst (DC), and ameloblastoma (AM) always invite debate. Glucose transporter 1 (GLUT-1) is proven to be an indicator of metabolic behavior of several benign and malignant neoplasms.

AIM

The purpose of this study was to evaluate the expression of GLUT-1 in OKC, DC, and AM to understand their metabolic behavior.

MATERIALS AND METHODS

Immunohistochemical expression of GLUT-1 was evaluated in each of the 15 cases of OKC, DC, and AM. The number of labeled cells, staining intensity, and membrane or cytoplasmic expressions were the parameters assessed and analyzed using chi-square test.

RESULTS

All cases showed positive GLUT-1 expression: 86.6% OKC showed more than 50% labeled cells followed by DC (40%) and AM (26.5%); 53.3% OKC showed strong intensity in comparison to AM, which showed weak intensity in 53.3% cases; 86.6% of OKCs showed both membrane and cytoplasmic expression followed by DC (40%) and AM (26.6%), whereas 73.3% of AM showed only membrane expression followed by DC (60%) and OKC (13.3%).

CONCLUSION

Odontogenic keratocyst was found out to be more metabolically active followed by DC and AM.

Diagnostic Biomarkers in Oral Verrucous Carcinoma: A Systematic Review

Oral verrucous carcinoma (OVC), a low-grade variant of oral squamous cell carcinoma (OSCC), is most frequently seen in the oral cavity. No clear etiology has been found for this lesion, but human papilloma virus, chewing betel nuts, and ultraviolet radiation are suggested as probable causes. Differential diagnosis of OVC is challenging for oral pathologists. The aim of this study was to review the molecular-based approaches for differential diagnosis of OVC. An electronic search was conducted in Medline and Scopus from January 2004 to July 2015 limited to English language publications. Published papers on verrucous carcinoma (VC) were found according to the inclusion and exclusion criteria and analyzed qualitatively. Data extraction were performed according to PRISMA statement. A total of 423 articles were reviewed; out of which, 26 articles completely fulfilled the inclusion criteria. Most of the included studies investigated proliferative and apoptotic biomarkers such as p53 and Ki67. No definite conclusion was drawn for cytoskeletal biomarkers due to variability of factors and lack of significant expression. However, it seems that cytokeratin10 (CK 10) can be useful for differentiation of OVC and benign squamous lesions. Among cell surface and extracellular matrix biomarkers tissue biomarkers, matrix metalloproteinase (MMP)-2, -9, CD31 and CD68 seem to be useful for differentiation of OVC and OSCC and glucose transporter-1 (GLUT-1) can help in differentiation of OVC from oral epithelial dysplasia. Differences among OVC, OSCC and normal epithelium in expression profiles of the investigated biomarkers help in their differential diagnosis; although, clinicohistopathological similarities among verrucous hyperplasia, noninvasive OVC and invasive well-differentiated OSCC make the diagnosis difficult. Further studies are required to better differentiate these oral lesions.

Prognostic value of GLUT-1 expression in oral squamous cell carcinoma: A prisma-compliant meta-analysis

BACKGROUND

A variety of studies have evaluated the correlation between glucose transporter-1 (GLUT-1) expression and prognosis of oral squamous cell carcinoma (OSCC); however, the results were inconsistent and inconclusive. A meta-analysis was performed to assess the prognostic significance of GLUT-1 in OSCC.

METHODS

Electronic databases of PubMed, Embase, and Web of Science were searched for relevant studies. The last search was updated on July 2016. Odds ratio (OR) and 95% confidence interval (CI) were pooled to evaluate the relationship between GLUT-1 and clinical features and hazard ratio (HR) and 95% CI were combined to measure the effect of GLUT-1 on overall survival (OS). P value < 0.05 was considered as statistically significant.

RESULTS

A total of 13 studies with 1301 subjects were included for meta-analysis. The pooled data showed that high GLUT-1 expression was associated with advanced tumor stages (n = 7, OR = 2.99, 95% CI: 2.01-4.46, P < 0.001), higher tumor grade (n = 5, OR = 3.34, 95%CI: 1.12-9.94, P = 0.031), tumor size (n = 5, OR = 3.36, 95%CI: 2.04-5.51, P < 0.001), lymph node metastasis (n = 5, OR = 3.15, 95%CI: 1.89-5.25, P < 0.001), tobacco use (n = 3, OR = 2.18, 95%CI: 1.18-4.01, P = 0.013), and distant metastasis (n = 2, OR = 3.06, 95%CI: 1.19-7.9, P = 0.02). Furthermore, increased GLUT-1 expression was also correlated with shorter OS (n = 8, HR = 1.88, 95%CI: 1.51-2.33, P < 0.001). No significant publication bias was detected in this meta-analysis.

CONCLUSION

GLUT-1 overexpression was in connection with aggressive clinical features and worse OS in OSCC. However, further studies are still needed to verify whether GLUT-1 could serve as a prognostic biomarker for OSCC.

The role of hypoxia in oral cancer and potentially malignant disorders: a review

Oral and oropharyngeal cancer are major health problems globally with over 500 000 new cases diagnosed annually. Despite the fact that oral cancer is a preventable disease and has the potential for early detection, the overall survival rate remains at around 50%. Most oral cancer cases are preceded by a group of clinical lesions designated 'potentially malignant disorders'. It is difficult to predict if and when these lesions may transform to malignancy, and in turn it is difficult to agree on appropriate management strategies. Understanding underlying molecular pathways would help in predicting the malignant transformation of oral potentially malignant disorders and ultimately identifying effective methods for early detection and prevention of oral cancer. Reprogramming energy metabolism is an emerging hallmark of cancer that is predominantly controlled by hypoxia-induced genes regulating angiogenesis, tumour vascularization, invasion, drug resistance and metastasis. This review aims to highlight the role of hypoxia in oral carcinogenesis and to suggest future research implications in this arena.

Immunohistochemical Expression of GLUT-1 and HIF-1α in Tooth Germ, Ameloblastoma, and Ameloblastic Carcinoma

Hypoxia-inducible factor-1α (HIF-1α) promotes proteins that enable cell survival during hypoxia, such as glucose transporter 1 (GLUT-1). Their coexpression has been associated with aggressiveness in malignancies and has not been studied in odontogenic tumors. Immunohistochemical expression of HIF-1α and GLUT-1 was analyzed in 13 tooth germs (TGs), 55 ameloblastomas (AMs), and 3 ameloblastic carcinomas (ACs). HIF-1α was negative in all TGs, and just 1 case of AM and 1 of AC had nuclear positivity. GLUT-1 expressed in ameloblastic cells of all TGs, AMs, and ACs, with an increasing intensity, respectively, and was significantly higher in solid AM than in unicystic AM (P = .041). Absence of nuclear HIF-1α in TGs and most AMs suggest that GLUT-1 may be induced by alternative pathways to hypoxia. However, in ACs, HIF-1α may be activated; however, to confirm this, additional cases are needed. GLUT-1 overexpression could be related to aggressiveness in AMs and ACs and must represent a normal metabolite in TGs.

Prognostic significance of monocarboxylate transporter expression in oral cavity tumors

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of cancer. The majority of patients present advanced stage disease and has poor survival. Therefore, it is imperative to search for new biomarkers and new alternative and effective treatment options. Most cancer cells rely on aerobic glycolysis to generate energy and metabolic intermediates. This phenotype is a hallmark of cancer, characterized by an increase in glucose consumption and production of high amounts of lactate. Consequently, cancer cells need to up-regulate many proteins and enzymes related with the glycolytic metabolism. Thus, the aim of this study was to characterize metabolic phenotype of oral cavity cancers (OCC) by assessing the expression pattern of monocarboxylate transporters (MCTs) 1, 2 and 4 and other proteins related with the glycolytic phenotype.

MATERIAL AND METHODS

We evaluated the immunohistochemical expression of MCT1, MCT4, CD147, GLUT1 and CAIX in 135 human samples of OCC and investigated the correlation with clinicopathological parameters and the possible association with prognosis.

RESULTS

We observed that all proteins analyzed presented significantly higher plasma membrane expression in neoplastic compared to non-neoplastic samples. MCT4 was significantly associated with T-stage and advanced tumoral stage, while CD147 was significantly correlated with histologic differentiation. Interestingly, tumors expressing both MCT1 and MCT4 but negative for MCT2 were associated with shorter overall survival.

CONCLUSION

Overexpression of MCT1/4, CD147, GLUT1 and CAIX, supports previous findings of metabolic reprograming in OCC, warranting future studies to explore the hyper-glycolytic phenotype of these tumors. Importantly, MCT expression revealed to have a prognostic value in OCC survival.

Oral verrucous carcinoma: From multifactorial etiology to diverse treatment regimens (Review)

Oral verrucous carcinoma (OVC) is a verrucous variant of oral squamous cell carcinoma (OSCC), which accounts for 2-12% of all oral carcinomas with a 5-year survival rate of only approximately 50%. Enormous effort has been dedicated to this cancer, and the past decades have witnessed significant advances in relevant diagnostic and therapeutic approaches. Currently, there exist three challenges from primary sub-fields of research and clinical practice of the cancer, namely multifactorial etiology, complex molecular mechanism, and deficient treatment. This study reviews the existing literature on the cancer, encompassing its etiology, clinical manifestations and pathology, molecular mechanism, diagnosis and differential diagnosis, and treatment. For improved treatment of OVC, multifactorial etiology analysis, incorporation of effective biomarkers for mechanism illustration, and integration of multidisciplinary modalities are expounded, in an attempt to resolve the challenges and to provide a useful guide for future research in the field.

Expression of GLUT-1 in oral squamous cell carcinoma in tobacco and non-tobacco users

BACKGROUND

GLUTs are a family of proteins that mediate glucose transport through the membrane, expressed in head and neck squamous cell carcinoma. GLUT-1 positivity in malignant cells indicates increased proliferative activity, energy requirements, aggressive behaviour and poor radiation response.

AIM

To observe the expression of GLUT-1 protein in oral squamous cell carcinoma in tobacco and non-tobacco users and to correlate the expression with histopathological grading and pathological staging.

METHODS

50 cases (25 tobacco and 25 non-tobacco) of oral squamous cell carcinoma, selected during period of August 2014 to July 2015. Histopathological grading, TNM and staging were done. Immunohistochemical staining was performed using standard protocol for paraffin embedded sections. Analysis was performed on SPSS software (Windows version 17.0).

RESULTS

Significant association of GLUT-1 expression was found with history of tobacco (p < 0.001), Bryne's grade (p < 0.001), tumour size (p = 0.001), nodal metastasis (p = 0.022) and stage (p < 0.001). Higher GLUT-1 expression in stage II, stage III and stage IV was found as compared to stage I. GLUT-1 immunoexpression also shows progressive switch from membranous to cytoplasmic to combined location correlating with histopathologic grade and pTNM stage.

CONCLUSION

GLUT-1 expression correlates significantly with histological grade and pTNM staging of oral squamous cell carcinoma. It also significantly correlates with tobacco addiction. Thus, GLUT-1 expression may serve as a biomarker for patients of oral squamous cell carcinoma.