β-catenin expression in areca quid chewing-associated oral squamous cell carcinomas and upregulated by arecoline in human oral epithelial cells

Cancer stem cells in head and neck squamous cell carcinoma and its associated markers: A review

ABSTRACT

Evidences of the current research say that cancer is multifactorial with varied mechanisms of origin. Most theories evolve either intrinsic (genetic) or extrinsic factors like tobacco and alcoholism as the major cause of oral cancer in India. There is growing evidence that human papilloma virus may act as a co-carcinogen, along with tobacco, in the causation of cancers. The cells being triggered by the agents may be somatic (differentiated functional cell) or a normal stem cell with multipotency or even the transient proliferative cells derived from the stem cells. These stem cells possess several features like slow cell cycle, ability to extrude chemotherapeutic drugs, exhibit epithelial mesenchymal transition, and inhibit apoptosis. Targeting these progenitor stem cells may aid in improving the overall prognosis of the patient. These cancer stem cells are targeted using various markers that are apparently more or less specific to various types of stem cells.

MiR-34a functions as a tumor suppressor in oral cancer through the inhibition of the Axl/Akt/GSK-3β pathway

Background/purpose

Oral cancer is a prevalent malignancy affecting men globally. This study aimed to investigate the regulatory role of miR-34a in oral cancer cells through the Axl/Akt/glycogen synthase kinase-3β (GSK-3β) pathway and its impact on cellular malignancy.

Materials and methods

We examined the effects of miR-34a overexpression on the malignancy of oral cancer cells. Multiple oral cancer cell lines were assessed to determine the correlation between endogenous miR-34a and Axl levels. Transfection experiments with miR-34a were conducted to analyze its influence on Axl mRNA and protein expression. Luciferase reporter assays were performed to investigate miR-34a's modulation of Axl gene transcription. Manipulation of miR-34a expression was utilized to demonstrate its regulatory effects on oral cancer cells through the Axl/Akt/GSK-3β pathway.

Results

Overexpression of miR-34a significantly suppressed the malignancy of oral cancer cells. We observed an inverse correlation between endogenous miR-34a and Axl levels across multiple oral cancer cell lines. Transfection of miR-34a resulted in decreased Axl mRNA and protein expression, and luciferase reporter assays confirmed miR-34a-mediated modulation of Axl gene transcription. The study revealed regulatory effects of miR-34a on oral cancer cells through the Axl/Akt/GSK-3β pathway, leading to alterations in downstream target genes involved in cellular proliferation and tumorigenesis.

Conclusion

Our findings highlight the significance of the miR-34a/Axl/Akt/GSK-3β signaling axis in modulating the malignancy of oral cancer cells. Targeting miR-34a may hold therapeutic potential in oral cancer treatment, as manipulating its expression can attenuate the aggressive behavior of oral cancer cells via the Axl/Akt/GSK-3β pathway.

Prognostic and Clinicopathological Significance of the Aberrant Expression of β-Catenin in Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

Simple Summary

β-catenin is a multifunctional protein whose physiological functions are mainly related to the maintenance of cell-cell adhesion by forming complexes with the adhesion molecule E-cadherin, both responsible for the preservation of squamous epithelia homeostasis. The loss of β-catenin expression in the cell membrane, the failure of cytoplasmic degradation mechanisms—essentially related to the activation of Wnt canonical oncogenic pathway—and/or its translocation to the nucleus—developing actions as a transcription factor of oncogenes—are aberrant mechanisms with oncogenic implications in oral carcinogenesis. In this systematic review and meta-analysis on 41 studies and 2746 oral squamous cell carcinoma (OSCC) patients we demonstrate that the aberrant expression of β-catenin—mainly the immunohistochemical analysis of its loss in the cell membrane—behaves as a prognostic biomarker, significantly associated with poor survival, essentially linked to the increased risk for the development of lymph node metastases, higher tumour size and clinical stage in these patients.

Abstract

This systematic review and meta-analysis aims to evaluate the prognostic and clinicopathological significance of the aberrant expression of β-catenin (assessed through the immunohistochemical loss of membrane expression, cytoplasmic and nuclear expression) in oral squamous cell carcinoma (OSCC). We searched for primary-level studies published before October-2021 through PubMed, Embase, Web of Science, Scopus, and Google Scholar, with no limitation in regard to their publication date or language. We evaluated the methodological quality and risk of bias of the studies included using the QUIPS tool, carried out meta-analyses, explored heterogeneity and their sources across subgroups and meta-regression, and conducted sensitivity and small-study effects analyses. Forty-one studies (2746 patients) met inclusion criteria. The aberrant immunohistochemical expression of β-catenin was statistically associated with poor overall survival (HR = 1.77, 95% CI = 1.20–2.60, p = 0.004), disease-free survival (HR = 2.44, 95% CI = 1.10–5.50, p = 0.03), N+ status (OR = 2.39, 95% CI = 1.68–3.40, p < 0.001), higher clinical stage (OR = 2.40, 95% CI = 1.58–3.63, p < 0.001), higher tumour size (OR = 1.76, 95% CI = 1.23–2.53, p = 0.004), and moderately-poorly differentiated OSCC (OR = 1.57, 95% CI = 1.09–2.25, p = 0.02). The loss of β-catenin in the cell membrane showed the largest effect size in most of meta-analyses (singularly for poor overall survival [HR = 2.37, 95% CI = 1.55–3.62, p < 0.001], N+ status [OR = 3.44, 95% CI = 2.40–4.93, p < 0.001] and higher clinical stage [OR = 2.51, 95% CI = 1.17–5.35, p = 0.02]). In conclusion, our findings indicate that immunohistochemical assessment of the aberrant expression of β-catenin could be incorporated as an additional and complementary routine prognostic biomarker for the assessment of patients with OSCC.

Does Loss of Immunohistochemical Expression of Glypican 3 in Oral Squamous Cell Carcinoma Play a Role in the Wnt/β-catenin Signaling Pathway?

Glypican 3 (GPC3) is a cell membrane protein and plays a dual role, as a tumor suppressor and oncogene, depending on its structure. It is known to regulate the Wnt/β-catenin signaling pathway and affect cell growth and proliferation. β-catenin plays a major oncogenic role in progression of oral squamous cell carcinoma (OSCC); thus, this study aimed to explore the relationship between β-catenin and GPC3 in OSCC. Immunoexpression of GPC3 and β-catenin was evaluated semiquantitatively in tumor tissue (n=80) and normal oral mucosa tissue (n=20). For GPC3, the percentage of stained cells and the staining intensity were assessed. For β-catenin, the percentage of stained cells, localization, and intensity of staining were assessed at the tumor-invasive front. The Pearson correlation was used to determine the correlation between the GPC3 and β-catenin immunoreactivity. Significantly decreased expression of GPC3 (P=0.008) and a highly significant difference in the case of localization of β-catenin (P=0.0001) were observed in OSCC when compared with normal oral mucosa. Cytoplasmic expression with a shift of β-catenin expression to the nucleus was seen in OSCC in comparison with primarily membranous and membranous and cytoplasmic staining in normal mucosa. A significant difference was observed with respect to localization of stain, with β-catenin staining moving to the nuclear compartment with an increase in the tumor grade (P=0.011). No correlation was observed between β-catenin and GPC3 expression in OSCC cases. It is concluded that loss of expression of GPC3 in OSCC compared with normal oral mucosa indicates that it plays the role of a tumor suppressor gene in OSCC and its expression is therefore silenced in OSCC.

Expression of β-catenin in oral leukoplakia and oral submucous fibrosis: An immunohistochemical study

Background

Oral potentially malignant disorders have increased propensity to turn malignant than its apparently normal counterparts. Histopathological examination, although gold standard, needs adjunct technique to give accurate diagnosis. Immunohistochemistry has proved to be a promising adjunct to aid in the diagnosis so far. The quest for a definitive marker is still on. Beta-catenin (β-catenin), a structural protein has been evaluated to identify its likely role in malignant transformation of potentially malignant lesions and possibly designate it as one of the identifiable signature molecules in the transformation.

Aim and Objective

To evaluate and estimate the expression of β-catenin in different grades of dysplasia, oral submucous fibrosis (OSMF) and normal mucosa and compare the same.

Methodology

A total number of 40 cases including different grades of dysplasia, OSMF and normal mucosa were immunohistochemically stained, location and intensity of its expression were evaluated for β-catenin. The results were statistically analyzed using the one-way analysis of variance and Chi-square test.

Results

The expression of β-Catenin in the cytoplasm as well as in the nucleus increased from mild-to-moderate dysplasia to OSMF and to severe epithelial dysplasia in an increasing order. The expression is seen to translocate from membranous to cytoplasm to nucleus indicating a proliferative potential in these group of lesions.

Conclusion

β-catenin is a promising marker which indicates the malignant transformation potential in the higher grades of dysplasia and OSMF.

A Review on Role of Arecoline and Its Metabolites in the Molecular Pathogenesis of Oral Lesions with an Insight into Current Status of Its Metabolomics

Areca nut consumption is a popular habit in Southeast Asian countries. One of the important biologically active alkaloids of areca nut is arecoline, which plays a role in mediating the development of several pathologies of the primary exposure site, the oral cavity. Studies on the metabolism of arecoline revealed the formation of several metabolites which themselves might be toxic. Moreover, polymorphisms in genes encoding enzymes involved in the metabolism of arecoline might predispose an organism towards the development of oral cancer. The present review tries to accumulate all the relevant existing literature and then elucidate the molecular mechanism by which arecoline plays a role in the development of oral submucous fibrosis and oral cancer. Existing information regarding arecoline metabolism, enzymes involved in the metabolic process and biological effects of the metabolites of arecoline have also been compiled and compared to study the toxicity of metabolites with its parent compound arecoline and whether they play any role in the pathogenesis of oral cancer mediated by areca nut consumption. A repertoire of molecular targets has come up in the discussion whose expression profile is perturbed by arecoline. Construction of induction cascade from existing literature has given an idea about the process of molecular pathogenesis. The summarized and analysed data can help to determine the molecular mechanism and drug targets, which in turn could be helpful in the prevention or treatment of these pathological conditions. It also brings into light areas where further research needs to be directed.

The Significance of the Dysregulation of Canonical Wnt Signaling in Head and Neck Squamous Cell Carcinomas

The knowledge about the molecular alterations which are found in head and neck squamous cell carcinomas (HNSCC) has much increased in recent years. However, we are still awaiting the translation of this knowledge to new diagnostic and therapeutic options. Among the many molecular changes that are detected in head and neck cancer, the abnormalities in several signaling pathways, which regulate cell proliferation, cell death and stemness, seem to be especially promising with regard to the development of targeted therapies. Canonical Wnt signaling is a pathway engaged in the formation of head and neck tissues, however it is not active in adult somatic mucosal cells. The aim of this review paper is to bring together significant data related to the current knowledge on the mechanisms and functional significance of the dysregulation of the Wnt/β-catenin pathway in head and neck tumors. Research evidence related to the role of Wnt signaling activation in the stimulation of cell proliferation, migration and inhibition of apoptosis in HNSCC is presented. Moreover, its role in promoting stemness traits in head and neck cancer stem-like cells is described. Evidence corroborating the hypothesis that the Wnt signaling pathway is a very promising target of novel therapeutic interventions in HNSCC is also discussed.

Chemistry, metabolism and pharmacology of carcinogenic alkaloids present in areca nut and factors affecting their concentration

Areca Nut (AN), the seed of tropical palm tree Areca catechu, is a widely chewed natural product with estimated 600 million users across the world. Various AN products, thriving in the market, portray 'Areca nut' or 'Supari' as mouth freshener and safe alternative to smokeless tobacco. Unfortunately, AN is identified as a Group 1 human carcinogen by International Agency for Research on Cancer (IARC). Wide variation in the level of alkaloids, broadly ranging from 2 to 10 mg/gm dry weight, is observed in diverse variety of AN sold worldwide. For the first time, various factors influencing the formation of carcinogenic alkaloids in AN at various stages, including during the growth, processing, and storage of the nut, are discussed. Current review illustrates the mechanism of cancer induction by areca alkaloids in humans and also compiles dose-dependent pharmacology and toxicology data of arecoline, the most potent carcinogenic alkaloid in AN. Careful monitoring of the arecoline content in AN can potentially be used as a tool in product surveillance studies to identify the variations in characteristics of various AN sample sold worldwide. The article will help to generate public awareness and sensitize the government bodies to initiate campaigns against AN use and addiction.

Impact of CCL4 gene polymorphisms and environmental factors on oral cancer development and clinical characteristics

In Taiwan, oral cancer has causally been associated with environmental carcinogens. CCL4 (C-C chemokine ligand 4), a macrophage inflammatory protein with a key role in inflammation and immune-regulation, was implicated in carcinogenesis by facilitating instability in the tumor environment. The purpose of this study was to identify gene polymorphisms of CCL4 specific to patients with oral squamous cell carcinoma (OSCC) susceptibility and clinicopathological characteristics. A total of 2,053 participants, including 1192 healthy people and 861 patients with oral cancer, were recruited for this study. Three single-nucleotide polymorphisms (SNPs) of the CCL4 gene were analyzed by a real-time PCR. We found that the T/T homozygotes of CCL4 rs1634507 G/T polymorphism and the GG haplotype of 2 CCL4 SNPs (rs1634507 and rs10491121) combined were associated with oral-cancer susceptibility. In addition, TA haplotype significantly decreased the risks for oral cancer by 0.118 fold. Among 1420 smokers, CCL4 polymorphisms carriers with the betel-nut chewing habit had a 15.476–20.247-fold greater risk of having oral cancer compared to CCL4 wild-type (WT) carriers without the betel-nut chewing habit. Finally, patients with oral cancer who had A/G heterozygotes of CCL4 rs10491121 A/G polymorphism showed a lower risk for an advanced tumor size (> T2) (p=0.046), compared to those patients with AA homozygotes. Our results suggest that the CCL4 rs1634507 SNP have potential predictive significance in oral carcinogenesis. Gene-environment interactions of CCL4 polymorphisms might influence oral-cancer susceptibility. CCL4 rs10491121 may be a factor to predict the tumor size in OSCC patients.

EMODIN DOWNREGULATES CELL PROLIFERATION MARKERS DURING DMBA INDUCED ORAL CARCINOGENESIS IN GOLDEN SYRIAN HAMSTERS

Background:

Cell-cycle disruption is the major characteristic features of neoplastic transformation and the status of cell-cycle regulators can thus be utilized to assess the prognostic significance in patients with cancer. The PCNA, cyclin D1, CDK4, CDK6 and survivin expression in the buccal mucosa was utilized to evaluate the Emodin efficacy on abnormal cell proliferation during 7,12-dimethylbenz(a)anthracene (DMBA) induced oral carcinogenesis in golden Syrian hamsters.

Materials and methods:

Topical application of DMBA, three times a week for 14 weeks, on the hamsters’ buccal pouches developed well differentiated squamous cell carcinoma.

Results:

Cyclin D1 and PCNA over-expression and up-regulation of CDK4, CDK6 and survivin were noticed in the buccal mucosa of hamsters treated with DMBA alone. Emodin administration (50mg/kg b.w) orally to hamsters treated with DMBA down-regulated the expression of cell proliferation markers in the buccal mucosa.

Conclusions:

The anti-cell proliferative role of Emodin is owing to its modulating efficacy on cell-cycle markers towards the tumor suppression during DMBA induced oral carcinogenesis.

The pharmacology, toxicology and potential applications of arecoline: a review

CONTEXT

Arecoline is an effective constituent of Areca catechu L. (Arecaceae) with various pharmacological effects. However, investigations also revealed that long use of arecoline could arouse some oral diseases.

OBJECTIVE

The present review gathers the fragmented information available in the literature (before 1 October 2015) regarding pharmacology and toxicology of arecoline. We also discussed the potential developments and applications of arecoline in the future.

METHODS

All the available information regarding the arecoline is compiled from scientific databases, including Science Direct, PubMed, Web of Science, Scopus, etc.

RESULTS

Previous research demonstrated that arecoline is one of the major effective constituents in A. catechu. Additionally, arecoline has a wide spectrum of pharmacological activities including effects on nervous, cardiovascular, digestive and endocrine systems and anti-parasitic effects. What's more, arecoline is reported to be the primary toxic constituent of A. catechu, and the main toxic effects include oral submucous fibrosis (OSF), oral squamous cell carcinoma (OSCC) and genotoxicity.

CONCLUSION

Arecoline has great potential to be a therapeutic drug for various ailments. However, further investigations are needed in the future to reduce or eliminate its toxicities before developing into new drug.

Beta-catenin in disease

In continuation with the previous review on “β-catenin in health”, in this review we discuss the role of β-catenin in the pathogenesis of common oral lesions in the oral and maxillofacial region- oral potentially malignant disorders, their progression to oral squamous cell carcinoma, salivary gland tumors and odontogenic tumours. This review is based on a pubmed search of all the lesions included in the review.

Identification of a combined biomarker for malignant transformation in oral submucous fibrosis

Background

Oral submucous fibrosis (OSF) is a chronic progressive disease of the oral cavity that is considered a common potentially malignant disorder in South Asia. Areca nut chewing is the main etiological factor, but its carcinogenic mechanism has yet to be proven. The purpose of this study was to identify the useful biomarkers in predicting high‐risk patients with OSF.

Methods

Thirty‐six cases of OSF and six cases of normal oral mucosa (NOM) were used for this study. Immunohistochemical staining was performed for Ki67, cyclin D1, p16, p53, β‐catenin, c‐Jun, c‐Met, and insulin‐like growth factor II mRNA‐binding protein 3 (IMP3). The expression patterns of NOM served as guidelines for the scoring system.

Results

The expression of Ki67, cyclin D1, c‐Met, IMP3, and β‐catenin showed a significant difference between OSF and NOM samples. The combined biomarkers of Ki67 and p16 showed significantly different expression between the transformation and non‐transformation groups. With discriminant analysis, we proposed a noble formula and cutoff value for predicting high‐risk patients with OSF.

Conclusion

The notable biomarkers in our present study were Ki67 and p16 showing significantly different expression levels between the transformation and non‐transformation groups. With the identification of high‐risk patients with OSF, we can expect to develop more intensive treatment modalities, leading to the reduction in cancer transformation rate from OSF.

Upregulation of vascular endothelial growth factor mRNA level is significantly related to progression and prognosis of oral squamous cell carcinomas

BACKGROUND/PURPOSE

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor. This study evaluated whether the VEGF mRNA level in oral squamous cell carcinoma (OSCC) tissue could be a biomarker to predict the progression and prognosis of OSCCs in Taiwan.

METHODS

This study used quantitative real-time reverse transcription-polymerase chain reaction (quantitative RT-PCR) to detect the VEGF mRNA levels in 60 OSCC specimens. Threshold cycle (CT) was defined as the PCR cycle number needed to generate a predetermined amount of DNA (threshold). The relative amount of tissue VEGF mRNA, standardized against the amount of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA, was expressed as ΔCT = (VEGF CT - GAPDH CT). For a chosen threshold, a smaller starting copy number of mRNA results in a higher CT value. Thus, the lower the ΔCT, the greater the copy number of VEGF mRNA in tissues.

RESULTS

The lower mean VEGF mRNA ΔCT value was significantly associated with OSCCs with larger tumor size (p = 0.040), positive lymph node metastasis (p = 0.023), and more advanced clinical stages (p = 0.008). VEGF mRNA ΔCT value < 4.2 (p = 0.026) was identified as an independent unfavorable prognosis factor using multivariate regression analyses. Moreover, Kaplan-Meier curve showed that OSCC patients with a VEGF mRNA ΔCT value < 4.2 had a significantly poorer overall survival than those with a VEGF mRNA ΔCT value ≥4.2 (log-rank test, p = 0.0427).

CONCLUSION

The OSCC tissue VEGF mRNA level can be used to predict the progression and prognosis of OSCCs in Taiwan.

The Protective Effects of Areca catechu Extract on Cognition and Social Interaction Deficits in a Cuprizone-Induced Demyelination Model

Schizophrenia is a serious psychiatric illness with an unclear cause. One theory is that demyelination of white matter is one of the main pathological factors involved in the development of schizophrenia. The current study evaluated the protective effects of Areca catechu nut extract (ANE) on a cuprizone-induced demyelination mouse model. Two doses of ANE (1% and 2%) were administered orally in the diet for 8 weeks. Animals subjected to demyelination showed impaired spatial memory and less social activity. In addition, mice subjected to demyelination displayed significant myelin damage in cortex and demonstrated a higher expression of NG2 and PDGFRα and AMPK activation. ANE treatment not only significantly enhanced cognitive ability and social activity, but also protected myelin against cuprizone toxicity by promoting oligodendrocyte precursor cell (OPC) differentiation. In addition, ANE treatment demonstrated significant dephosphorylation of AMPKα, indicating a regulatory role for ANE in schizophrenia. This study showed that ANE treatment may enhance cognitive ability and social activity by facilitating OPC differentiation and protecting against myelin damage in cortex. Results also suggest the AMPK signaling pathway may be involved in this process.

Relevance of cancer initiating/stem cells in carcinogenesis and therapy resistance in oral cancer

Oral squamous cell carcinoma (OSCC) acquires the top most position among the other malignancies and patients die with this disease complication within 5years. One of the causes behind this scenario is the identified sub-population in heterogeneous tumor mass that are purported as cancer stem cells (CSCs) or tumor-initiating cells (TICs). Oral CSCs populations show upregulation of the stem cell related genes Oct-4, Nanog, Nestin, CK19, BMI-1, CD117 (c-kit), CD44 and CD133 with sunken expression of involucrin and CK13. This small proportion of tumor cells can sustain tumor growth, proliferation, invasion and distant metastasis playing a pivotal role in relapse of oral cancer. Unanimous risk factors include prevalent use of cigarette smoking, tobacco chewing with less explored HPV infection play an important role in origin of CSCs. Moreover, highly apoptotic resistant oral CSCs show enhanced protective autophagy for survival. Several studies report them to be more chemo and radiation resistant than non-stem cell population implicating the failure of the present cancer therapy. This resistance associated with normal stem cell protective mechanisms including increased expression of drug efflux pumps, alteration in program cell death, cell cycle, and DNA repair mechanisms. Notably, CSCs appear to play a major role in tumor recurrence and metastatic spread, common causes of the high morbidity and ultimately the death of the majority of patients with oral cancer. In this review we would like to highlight the intricate crosstalk of the cancer initiating/stem cells involved in carcinogenesis and potential hurdle to oral cancer therapy.

The expression of O(6) -methylguanine-DNA methyltransferase in human oral keratinocytes stimulated with arecoline

BACKGROUND

O(6) -methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that can protect cells from carcinogenic effects of alkylating agents by removing adducts from the O(6) position of guanine. Evidences indicated that areca quid chewing may increase the risk of oral squamous cell carcinoma (OSCC). This study was to investigate the role of MGMT expression in OSCCs and the normal oral tissues.

METHODS

Thirty-two OSCCs from areca quid chewers and ten normal oral tissue biopsy samples without areca quid chewing were analyzed by the immunohistochemistry for MGMT. Primary human oral keratinocytes (HOKs) were challenged with arecoline, the major alkaloid of areca nut, by Western blot. Nicotine, an important component of cigarette smoke, was added to find the possible regulatory mechanisms.

RESULTS

Significant association was observed between low MGMT expression and advanced clinical stage of OSCCs and lymph node metastasis (P = 0.03). MGMT expression was significantly higher in patients only chewing areca quid than patients both chewing areca quid and smoking (P = 0.028). Arecoline was found to elevate MGMT expression in a dose- and time-dependent manner. The addition of nicotine was found to enhance arecoline-induced MGMT expression.

CONCLUSION

Our results indicate that MGMT could be used clinically as a predictive marker for tumor processing, the potential for lymph node metastasis as well as advanced clinical stage. MGMT expression was significantly upregulated by arecoline in HOKs. Nicotine has a synergistic effect of arecoline-induced MGMT expression. The cigarette smoking may act synergistically in the pathogenesis of OSCC in areca quid chewers via the upregulation of MGMT.