Mutations of the APC, beta-catenin, and axin 1 genes and cytoplasmic accumulation of beta-catenin in oral squamous cell carcinoma

Wnt/β-catenin-YAP axis in the pathogenesis of primary intraosseous carcinoma NOS, deriving from odontogenic keratocyst

Odontogenic tumors (OGTs), which originate from cells of odontogenic apparatus and their remnants, are rare entities. Primary intraosseous carcinoma NOS (PIOC), is one of the OGTs, but it is even rarer and has a worse prognosis. The precise characteristics of PIOC, especially in immunohistochemical features and its pathogenesis, remain unclear. We characterized a case of PIOC arising from the left mandible, in which histopathological findings showed a transition from the odontogenic keratocyst to the carcinoma. Remarkably, the tumor lesion of this PIOC prominently exhibits malignant attributes, including invasive growth of carcinoma cell infiltration into the bone tissue, an elevated Ki-67 index, and lower signal for CK13 and higher signal for CK17 compared with the non-tumor region, histopathologically and immunohistopathologically. Further immunohistochemical analyses demonstrated increased expression of ADP-ribosylation factor (ARF)-like 4c (ARL4C) (accompanying expression of β-catenin in the nucleus) and yes-associated protein (YAP) in the tumor lesion. On the other hand, YAP was expressed and the expression of ARL4C was hardly detected in the non-tumor region. In addition, quantitative RT-PCR analysis using RNAs and dot blot analysis using genomic DNA showed the activation of Wnt/β-catenin signaling and epigenetic alterations, such as an increase of 5mC levels and a decrease of 5hmC levels, in the tumor lesion. A DNA microarray and a gene set enrichment analysis demonstrated that various types of intracellular signaling would be activated and several kinds of cellular functions would be altered in the pathogenesis of PIOC. Experiments with the GSK-3 inhibitor revealed that β-catenin pathway increased not only mRNA levels of ankyrin repeat domain1 (ANKRD1) but also protein levels of YAP and transcriptional co-activator with PDZ-binding motif (TAZ) in oral squamous cell carcinoma cell lines. These results suggested that further activation of YAP signaling by Wnt/β-catenin signaling may be associated with the pathogenesis of PIOC deriving from odontogenic keratocyst in which YAP signaling is activated.

ELOVL6 promotes the progression of head and neck squamous cell carcinoma via activating WNT/β-catenin pathway

This study was to explore the role of ELOVL6 in the development of head and neck squamous cell carcinoma (HNSCC). Considering its previously identified oncogenic role in hepatocellular carcinoma. ELOVL6 gene expression, clinicopathological analysis, enrichment analysis, and immune infiltration analysis were based on the data from Gene Expression Omnibus and The Cancer Genome Atlas, with additional bioinformatics analyses performed. Human HNSCC tissue microarray and cell lines were used. The expression of ELOVL6 in HNSCC was detected by quantitative polymerase chain reaction, immunohistochemistry assay, and western blot analysis. The proliferation ability of HNSCC cells, invasion, and apoptosis were evaluated using cell counting kit-8 method, Transwell assay, and flow cytometry, respectively. Based on the data derived from the cancer databases and our HNSCC cell and tissue studies, we found that ELOVL6 was overexpressed in HNSCC. Moreover, ELOVL6 expression level had a positive correlation with clinicopathology of HNSCC. Gene set enrichment analysis showed that ELOVL6 affected the occurrence of HNSCC through WNT signaling pathway. Functional experiments demonstrated that ELOVL6 knockdown inhibited the proliferation and invasion of HNSCC cells while promoting apoptosis. Additionally, compound 3f, an agonist of WNT/β-catenin signaling pathway, enhances the effect of ELOVL6 on the progression of HNSCC cells. ELOVL6 is upregulated in HNSCC and promotes the development of HNSCC cells by inducing WNT/β-catenin signaling pathway. ELOVL6 stands a potential target for the treatment of HNSCC and a prognosis indicator of human HNSCC.

Promoter DNA methylation patterns in oral, laryngeal and oropharyngeal anatomical regions are associated with tumor differentiation, nodal involvement and survival

Differentially methylated regions (DMRs) can be used as head and neck squamous cell carcinoma (HNSCC) diagnostic, prognostic and therapeutic targets in precision medicine workflows. DNA from 21 HNSCC and 10 healthy oral tissue samples was hybridized to a genome-wide tiling array to identify DMRs in a discovery cohort. Downstream analyses identified differences in promoter DNA methylation patterns in oral, laryngeal and oropharyngeal anatomical regions associated with tumor differentiation, nodal involvement and survival. Genome-wide DMR analysis showed 2,565 DMRs common to the three subsites. A total of 738 DMRs were unique to laryngeal cancer (n=7), 889 DMRs were unique to oral cavity cancer (n=10) and 363 DMRs were unique to pharyngeal cancer (n=6). Based on the genome-wide analysis and a Gene Ontology analysis, 10 candidate genes were selected to test for prognostic value and association with clinicopathological features. TIMP3 was associated with tumor differentiation in oral cavity cancer (P=0.039), DAPK1 was associated with nodal involvement in pharyngeal cancer (P=0.017) and PAX1 was associated with tumor differentiation in laryngeal cancer (P=0.040). A total of five candidate genes were selected, DAPK1, CDH1, PAX1, CALCA and TIMP3, for a prevalence study in a larger validation cohort: Oral cavity cancer samples (n=42), pharyngeal cancer tissues (n=25) and laryngeal cancer samples (n=52). PAX1 hypermethylation differed across HNSCC anatomic subsites (P=0.029), and was predominantly detected in laryngeal cancer. Kaplan-Meier survival analysis (P=0.043) and Cox regression analysis of overall survival (P=0.001) showed that DAPK1 methylation is associated with better prognosis in HNSCC. The findings of the present study showed that the HNSCC subsites oral cavity, pharynx and larynx display substantial differences in aberrant DNA methylation patterns, which may serve as prognostic biomarkers and therapeutic targets.

The scaffold protein AXIN1: gene ontology, signal network, and physiological function

AXIN1, has been initially identified as a prominent antagonist within the WNT/β-catenin signaling pathway, and subsequently unveiled its integral involvement across a diverse spectrum of signaling cascades. These encompass the WNT/β-catenin, Hippo, TGFβ, AMPK, mTOR, MAPK, and antioxidant signaling pathways. The versatile engagement of AXIN1 underscores its pivotal role in the modulation of developmental biological signaling, maintenance of metabolic homeostasis, and coordination of cellular stress responses. The multifaceted functionalities of AXIN1 render it as a compelling candidate for targeted intervention in the realms of degenerative pathologies, systemic metabolic disorders, cancer therapeutics, and anti-aging strategies. This review provides an intricate exploration of the mechanisms governing mammalian AXIN1 gene expression and protein turnover since its initial discovery, while also elucidating its significance in the regulation of signaling pathways, tissue development, and carcinogenesis. Furthermore, we have introduced the innovative concept of the AXIN1-Associated Phosphokinase Complex (AAPC), where the scaffold protein AXIN1 assumes a pivotal role in orchestrating site-specific phosphorylation modifications through interactions with various phosphokinases and their respective substrates.

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.

Comprehending the crosstalk between Notch, Wnt and Hedgehog signaling pathways in oral squamous cell carcinoma - clinical implications

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a malignant oral cavity neoplasm that affects many people, especially in developing countries. Despite several advances that have been made in diagnosis and treatment, the morbidity and mortality rates due to OSCC remain high. Accumulating evidence indicates that aberrant activation of cellular signaling pathways, such as the Notch, Wnt and Hedgehog pathways, occurs during the development and metastasis of OSCC. In this review, we have articulated the roles of the Notch, Wnt and Hedgehog signaling pathways in OSCC and their crosstalk during tumor development and progression. We have also examined possible interactions and associations between these pathways and treatment regimens that could be employed to effectively tackle OSCC and/or prevent its recurrence.

CONCLUSIONS

Activation of the Notch signaling pathway upregulates the expression of several genes, including c-Myc, β-catenin, NF-κB and Shh. Associations between the Notch signaling pathway and other pathways have been shown to enhance OSCC tumor aggressiveness. Crosstalk between these pathways supports the maintenance of cancer stem cells (CSCs) and regulates OSCC cell motility. Thus, application of compounds that block these pathways may be a valid strategy to treat OSCC. Such compounds have already been employed in other types of cancer and could be repurposed for OSCC.

Roles of the Wnt Signaling Pathway in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the most common type of head and neck tumor. It is a high incidence malignant tumor associated with a low survival rate and limited treatment options. Accumulating conclusions indicate that the Wnt signaling pathway plays a vital role in the pathobiological process of HNSCC. The canonical Wnt/β-catenin signaling pathway affects a variety of cellular progression, enabling tumor cells to maintain and further promote the immature stem-like phenotype, proliferate, prolong survival, and gain invasiveness. Genomic studies of head and neck tumors have shown that although β-catenin is not frequently mutated in HNSCC, its activity is not inhibited by mutations in upstream gene encoding β-catenin, NOTCH1, FAT1, and AJUBA. Genetic defects affect the components of the Wnt pathway in oral squamous cell carcinoma (OSCC) and the epigenetic mechanisms that regulate inhibitors of the Wnt pathway. This paper aims to summarize the groundbreaking discoveries and recent advances involving the Wnt signaling pathway and highlight the relevance of this pathway in head and neck squamous cell cancer, which will help provide new insights into improving the treatment of human HNSCC by interfering with the transcriptional signaling of Wnt.

Evidence for AJUBA-catenin-CDH4-linked differentiation resistance of mesenchymal stem cells implies tumorigenesis and progression of head and neck squamous cell carcinoma: a single-cell transcriptome approach

An increasing number of reports indicate that mesenchymal stem cells (MSCs) play an essential role in promoting tumorigenesis and progression of head and neck squamous cell carcinoma (HNSCC). However, the molecular mechanisms underlying this process remain unclear. Using the MSC model system, this study analyzes the molecular pathway by which differentiation resistant MSCs promote HNSCC. MSCs were cultured in osteogenic differentiation media and harvested on days 12 and 19. Cells were stained for cell differentiation analysis using Alizarin Red. The osteogenesis-resistant MSCs (OR-MSCs) and MSC-differentiation-derived osteoblasts (D-OSTBs) were identified and subjected to the single-cell transcriptome analysis. Gene-specific analyses of these two sub-populations were performed for the patterns of differential expression. A total of 1 780 differentially expressed genes were determined to distinguish OR-MSCs significantly from D-OSTB. Notably, AJUBA, β-catenin, and CDH4 expression levels were upregulated considerably within the OR-MSCs compared to D-OSTBs. To confirm their clinical relevance, a survey of a clinical cohort revealed a high correlation among the expression levels of AJUBA, β-catenin and CDH4. The results shed new light that OR-MSCs participate in the development of HNSCC via a pathway mediated by AJUBA, β-catenin, CDH4, and CTNNB1, thereby implying that MSC-based therapy is a promising therapeutic approach in the management of HNSCC.

Glycogen synthase kinase 3β in tumorigenesis and oncotherapy (Review)

Glycogen synthase kinase 3β (GSK 3β), a multifunctional serine and threonine kinase, plays a critical role in a variety of cellular activities, including signaling transduction, protein and glycogen metabolism, cell proliferation, cell differentiation, and apoptosis. Therefore, aberrant regulation of GSK 3β results in a broad range of human diseases, such as tumors, diabetes, inflammation and neurodegenerative diseases. Accumulating evidence has suggested that GSK 3β is correlated with tumorigenesis and progression. However, GSK 3β is controversial due to its bifacial roles of tumor suppression and activation. In addition, overexpression of GSK 3β is involved in tumor growth, whereas it contributes to the cell sensitivity to chemotherapy. However, the underlying regulatory mechanisms of GSK 3β in tumorigenesis remain obscure and require further in‑depth investigation. In this review, we comprehensively summarize the roles of GSK 3β in tumorigenesis and oncotherapy, and focus on its potentials as an available target in oncotherapy.

Wnt/β-Catenin Signaling in Oral Carcinogenesis

Oral carcinogenesis is a complex and multifactorial process that involves cumulative genetic and molecular alterations, leading to uncontrolled cell proliferation, impaired DNA repair and defective cell death. At the early stages, the onset of potentially malignant lesions in the oral mucosa, or oral dysplasia, is associated with higher rates of malignant progression towards carcinoma in situ and invasive carcinoma. Efforts have been made to get insights about signaling pathways that are deregulated in oral dysplasia, as these could be translated into novel markers and might represent promising therapeutic targets. In this context, recent evidence underscored the relevance of the Wnt/β-catenin signaling pathway in oral dysplasia, as this pathway is progressively "switched on" through the different grades of dysplasia (mild, moderate and severe dysplasia), with the consequent nuclear translocation of β-catenin and expression of target genes associated with the maintenance of representative traits of oral dysplasia, namely cell proliferation and viability. Intriguingly, recent studies provide an unanticipated connection between active β-catenin signaling and deregulated endosome trafficking in oral dysplasia, highlighting the relevance of endocytic components in oral carcinogenesis. This review summarizes evidence about the role of the Wnt/β-catenin signaling pathway and the underlying mechanisms that account for its aberrant activation in oral carcinogenesis.

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.

Photodynamic Therapy in Melanoma - Where do we Stand?

BACKGROUND

Malignant melanoma is one of the most aggressive malignant tumors, with unpredictable evolution. Despite numerous therapeutic options, like chemotherapy, BRAF inhibitors and immunotherapy, advanced melanoma prognosis remains severe. Photodynamic therapy (PDT) has been successfully used as the first line or palliative therapy for the treatment of lung, esophageal, bladder, non melanoma skin and head and neck cancers. However, classical PDT has shown some drawbacks that limit its clinical application in melanoma.

OBJECTIVE

The most important challenge is to overcome melanoma resistance, due to melanosomal trapping, presence of melanin, enhanced oxidative stress defense, defects in the apoptotic pathways, immune evasion, neoangiogenesis stimulation.

METHOD

In this review we considered: (1) main signaling molecular pathways deregulated in melanoma as potential targets for personalized therapy, including PDT, (2) results of the clinical studies regarding PDT of melanoma, especially advanced metastatic stage, (3) progresses made in the design of anti-melanoma photosensitizers (4) inhibition of tumor neoangiogenesis, as well as (5) advantages of the derived therapies like photothermal therapy, sonodynamic therapy.

RESULTS

PDT represents a promising alternative palliative treatment for advanced melanoma patients, mainly due to its minimal invasive character and low side effects. Efficient melanoma PDT requires: (1) improved, tumor targeted, NIR absorbing photosensitizers, capable of inducing high amounts of different ROS inside tumor and vasculature cells, possibly allowing a theranostic approach; (2) an efficient adjuvant immune therapy.

CONCLUSION

Combination of PDT with immune stimulation might be the key to overcome the melanoma resistance and to obtain better, sustainable clinical results.

Dysregulation of ß-catenin, WISP1 and TCF21 predicts disease-specific survival and primary response against radio(chemo)therapy in patients with locally advanced squamous cell carcinomas of the head and neck

OBJECTIVE

The objective of this study was to determine the prognostic and predictive impact of β-catenin, TCF21 and WISP1 expression in patients with squamous cell carcinomas of the head and neck who underwent primary radiotherapy or concomitant chemoradiotherapy.

STUDY DESIGN

Prospective cohort study.

SETTING

University hospital.

PARTICIPANTS

Protein expression profiles of β-catenin, TCF21, WISP1 and p16 were determined by immunohistochemical analyses in tissue samples of 59 untreated patients. Expression was correlated with different outcome parameters.

MAIN OUTCOME MEASURES

Impact of TNM classification, grading, sex, age, gender, type of therapy, response to therapy and p16 status on disease-specific (DSS) and disease-free survival (DFS).

RESULTS

Patients with high expression of TCF21 were associated with significantly worse disease-specific survival (P = 0.005). In a multivariable analysis, TCF21 was a significant determinant of disease-specific survival. (HR 3.01; P = 0.036). Conversely, low expression of β-catenin (P = 0.025) and WISP1 (P = 0.037) revealed a better response to radiotherapy.

CONCLUSION

Since data show that TCF21 is a prognostic factor for disease-specific survival and WISP1 and ß-catenin are predictive factors for clinical outcome after definitive radiotherapy, further studies are warranted to prove these preliminary but very promising findings.

Current Insights into Oral Cancer Epigenetics

Epigenetic modifications have emerged into one of the cancer hallmarks, replacing the concept of malignant pathologies as being solely genetic-based conditions. The epigenetic landscape is responsible for normal development but also for the heterogeneity among tissues in terms of gene expression patterns. Dysregulation in these mechanisms has been associated with disease stage, and increased attention is now granted to cancer in order to take advantage of these modifications in terms of novel therapeutic strategies or diagnosis/prognosis tools. Oral cancer has also been subjected to epigenetic analysis with numerous studies revealing that the development and progression of this malignancy are partially induced by an altered epigenetic substrate together with genetic alterations and prolonged exposure to environmental risk factors. The present review summarizes the most important epigenetic modifications associated with oral cancer and also their potential to be used as new therapeutic targets.

E-Cadherin/β-Catenin Complex: A Target for Anticancer and Antimetastasis Plants/Plant-derived Compounds

Plants reputed to have cancer-inhibiting potential and putative active components derived from those plants have emerged as an exciting new field in cancer study. Some of these compounds have cancer-inhibiting potential in different clinical staging levels, especially metastasis. A few of them which stabilize cell-cell adhesions are controversial topics. This review article introduces some effective herbal compounds that target E-cadherin/β-catenin protein complex. In this article, at first, we briefly review the structure and function of E-cadherin and β-catenin proteins, Wnt signaling pathway, and its target genes. Then, effective compounds of the Teucrium persicum, Teucrium polium, Allium sativum (garlic), Glycine max (soy), and Brassica oleracea (broccoli) plants, which influence stability and cellular localization of E-cadherin/β-catenin complex, were studied. Based on literature review, there are some compounds in these plants, including genistein of soy, sulforaphane of broccoli, organosulfur compounds of garlic, and the total extract of Teucrium genus that change the expression of variety of Wnt target genes such as MMPs, E-cadherin, p21, p53, c-myc, and cyclin D1. So they may induce cell-cycle arrest, apoptosis and/or inhibition of Epithelial-Mesenchymal Transition (EMT) and metastasis.

WNT inhibitory factor 1 promoter hypermethylation is an early event during gallbladder cancer tumorigenesis that predicts poor survival

Gallbladder cancer (GBC) is the most common malignant tumor in the human biliary tract, but the lack of a marker for timely diagnosis leads to an extremely poor prognosis. In this study, we assessed CpG sites in the WIF-1 promoter using bisulfite sequencing PCR and methylation-specific PCR to detect methylation in gallbladder cancer and cholecystitis tissues. WIF-1 promoter methylation was present in 36 of 50 (72.0%) gallbladder cancers but only 5 of 20 (25.0%) cholecystitis tissues (P=0.000<0.05), suggesting that WIF-1 promoter methylation might participate in the malignant transformation of cholecystitis into gallbladder cancer. WIF-1 methylation was negatively correlated with WIF-1 protein expression by immunohistochemistry, demonstrating that WIF-1 expression is downregulated by promoter hypermethylation. We analyzed the prognosis of 50 GBC patients with 5years of follow-up. Univariate analysis revealed that patients with hypermethylated WIF-1 exhibited worse overall survival than those with hypomethylated WIF-1 (χ²=8.137, P=0.004<0.05). Furthermore, multivariate analysis revealed that WIF-1 methylation was an independent prognostic factor for 5-year overall survival (P=0.011). Therefore, WIF-1 methylation is a candidate as a marker for early gallbladder cancer diagnosis and prognosis.

Transcription factor AP-2β suppresses cervical cancer cell proliferation by promoting the degradation of its interaction partner β-catenin

Transcription factor AP-2β mediates the transcription of a number of genes implicated in mammalian development, cell proliferation, and carcinogenesis. Although the expression pattern of AP-2β has been analyzed in cervical cancer cell lines, the functions and molecular mechanism of AP-2β are unknown. Here, we found that AP-2β significantly inhibits TCF/LEF reporter activity. Moreover, AP-2β and β-catenin interact both in vitro through GST pull-down assays and in vivo by co-immunoprecipitation. We further identified the interaction regions to the DNA-binding domain of AP-2β and the 1-9 Armadillo repeats of β-catenin. Moreover, AP-2β binds with β-TrCP and promotes the degradation of endogenous β-catenin via the proteasomal degradation pathway. Immunohistochemistry analysis revealed a negative correlation between the two proteins in cervical cancer tissues and cell lines. Finally, functional analysis showed that AP-2β suppresses cervical cancer cell growth in vitro and in vivo by inhibiting the expression of Wnt downstream genes. Taken together, these findings demonstrated that AP-2β functions as a novel inhibitor of the Wnt/β-catenin signaling pathway in cervical cancer.

High-resolution Melting Analysis for Gene Scanning of Adenomatous Polyposis Coli (APC) Gene With Oral Squamous Cell Carcinoma Samples

BACKGROUND

There have been many different mutations reported for the large adenomatous polyposis coli (APC) tumor suppressor gene. APC mutations result in inactivation of APC tumor suppressor action, allowing the progression of tumorigenesis. The present study utilized a highly efficient method to identify APC mutations and investigated the association between the APC genetic variants Y486Y, A545A, T1493T, and D1822V and susceptibility to oral squamous cell carcinoma (OSCC).

METHODS

High-resolution melting (HRM) analysis was used to characterize APC mutations. Genomic DNA was extracted from 83 patient specimens of OSCC and 50 blood samples from healthy control subjects. The 14 exons and mutation cluster region of exon 15 were screened by HRM analysis. All mutations were confirmed by direct DNA sequencing.

RESULTS

Three mutations and 4 single nucleotide polymorphisms (SNPs) were found in this study. The mutations were c.573T>C (Y191Y) in exon 5, c.1005A>G (L335L) in exon 9, and c.1488A>T (T496T) in exon 11. Two SNPs, c.4479G>A (T1493T) and c.5465A>T (D1822V), were located in exon 15, whereas c.1458T>C (Y486Y) and c.1635G>A (A545A) were located in exon 11 and 13, respectively. There was no observed association between OSCC risk and genotype for any of the 4 APC SNPs.

CONCLUSIONS

The mutation of APC is rare in Taiwanese patients with OSCC. HRM analysis is a reliable, accurate, and fast screening method for APC mutations.

The Role of Wnt Signaling in Squamous Cell Carcinoma

Aberrant Wnt signaling pathway is a common feature of tumors and also plays important roles in tumor progression and metastasis of many cancer types. Various lines of evidence suggest that genetic defects affect Wnt pathway components, as well as epigenetic mechanisms that modulate the suppressors of Wnt pathway in oral squamous cell carcinoma. Recently, the newly discovered microRNAs are important molecular regulators in gene expression through transcription and translation repression. They play fundamental roles in a wide spectrum of biological functions, including cancer. In this review, we aim to accumulate recent research findings on the roles of Wnt/β-catenin signaling and discuss how microRNAs affect Wnt/β-catenin signaling in oral squamous cell carcinoma tumorigenesis. Apparently, investigations into the role of microRNAs with regard to the Wnt pathway in oral squamous cell carcinoma may help in the development of better strategies for tumor treatment.

Deregulation of secreted frizzled-related proteins is associated with aberrant β-catenin activation in the carcinogenesis of oral submucous fibrosis

Secreted frizzled-related proteins (SFRPs), the first identified Wnt antagonists, have been well recognized as tumor suppressors in multiple human cancers through suppressing the Wnt/β-catenin pathway. To better elucidate the mechanisms of SFRPs involved in the carcinogenesis of oral submucous fibrosis (OSF), one of the precancerous lesions of oral squamous cell carcinoma (OSCC), we investigated expression and localization of SFRP1, SFRP5, and β-catenin in normal oral epithelium, OSF, and OSCC tissues. We found that SFRP1 and SFRP5 were readily expressed in normal oral mucous tissues but gradually decreased in OSF early, moderately advanced, and advanced tissues and rarely expressed in OSCC tissues. We found the changes of SFRP1 localization and SFRP5 localization from nucleus to cytoplasm in the carcinogenesis of OSF. There is a significant association among reduced SFRP1, SFRP5, and cytoplasmic/nuclear β-catenin expression, which is correlated with higher tumor grade and stage of OSCC. We further found that SFRP1 and SFRP5 were frequently methylated in OSCC cases with betel quid chewing habit but not in normal oral mucous and different stages of OSF tissues, suggesting that methylation of SFRP1 and SFRP5 is tumor specific in the carcinogenesis of OSF. Taken together, our data demonstrated that reduced SFRP1 and SFRP5 by promoter methylation could lead to cytoplasmic/nuclear accumulation of β-catenin and tumor progression. The changes of SFRPs and β-catenin localization, as well as SFRPs' methylation, could be useful predictors or biomarkers of OSF malignant progression and prognosis.

Expression and promoter methylation of Wnt inhibitory factor-1 in the development of oral submucous fibrosis

Oral squamous cell carcinoma (OSCC) is a type of head and neck malignancy with a high mortality rate. Oral submucous fibrosis (OSF) is the pre-cancerous lesion of OSCC, whose molecular mechanisms in OSCC tumorigenesis remain largely unclear. Activation of the Wnt/β-catenin signaling pathway plays an important role in oral mucous carcinogenesis, although rare mutations of Wnt signaling molecules are found in OSCC, suggesting an epigenetic mechanism mediating aberrant Wnt/β‑catenin signaling in OSCC. Wnt inhibitory factor-1 (WIF1) is an Wnt antagonist, and its downregulation and methylation have been reported in a number of malignancies. However, the expression and methylation of WIF1 in the development of OSF have yet to be reported. In the present study, we investigated the WIF1 expression level by immuno-histochemical staining and semi‑quantitative RT-PCR in normal oral, OSF and OSCC tissues, as well as the methylation status by methylation-specific PCR and bisulfite genomic sequencing. The results showed that WIF1 was readily expressed in normal oral mucous tissues, but decreased gradually in OSF early, moderately advanced and advanced tissues, and was less expressed in OSCC tissues. Moreover, WIF1 was able to translocate from the nuclear to cytoplasm in OSF and OSCC tissues. Furthermore, WIF1 was frequently methylated in OSCC cases with betel quid chewing habit, but not in normal oral mucous and different stages of OSF tissues, suggesting WIF1 methylation is tumor-specific in the development of OSF. Thus, the results demonstrated that WIF1 is frequently downregulated or silenced by promoter methylation in the carcinogenesis of OSF, which serves as a potential epigenetic biomarker for the early detection of OSCC.

Gene and miRNA expression changes in squamous cell carcinoma of larynx and hypopharynx

Laryngo-pharyngeal squamous cell carcinomas are one of the most common head and neck cancers. Despite the presence of a large body of information, molecular biomarkers are not currently used in the diagnosis, treatment and management of patients for this group of cancer. Here, we have profiled expression of genes and microRNAs of larynx and hypopharynx tumors using high-throughput sequencing experiments. We found that matrix metalloproteinases along with SCEL, CRNN, KRT4, SPINK5, and TGM3 among others have significantly altered expression in these tumors. Alongside gene expression, the microRNAs hsa-miR-139, hsa-miR-203 and the hsa-miR-424/503 cluster have aberrant expression in these cancers. Using target genes for these microRNAs, we found the involvement of pathways linked to cell cycle, p53 signaling, and viral carcinogenesis significant (P-values 10(-13), 10(-9) and 10(-7) respectively). Finally, using an ensemble machine-learning tool, we discovered a unique 8-gene signature for this group of cancers that differentiates the group from the other tumor subsites of head and neck region. We investigated the role of promoter methylation in one of these genes, WIF1, and found no correlation between DNA methylation and down-regulation of WIF1. We validated our findings of gene expression, 8-gene signature and promoter methylation using q-PCR, data from TCGA and q-MSP respectively. Data presented in this manuscript has been submitted to the NCBI Geo database with the accession number GSE67994.

GSK-3 as potential target for therapeutic intervention in cancer

The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) was initially identified and studied in the regulation of glycogen synthesis. GSK-3 functions in a wide range of cellular processes. Aberrant activity of GSK-3 has been implicated in many human pathologies including: bipolar depression, Alzheimer's disease, Parkinson's disease, cancer, non-insulin-dependent diabetes mellitus (NIDDM) and others. In some cases, suppression of GSK-3 activity by phosphorylation by Akt and other kinases has been associated with cancer progression. In these cases, GSK-3 has tumor suppressor functions. In other cases, GSK-3 has been associated with tumor progression by stabilizing components of the beta-catenin complex. In these situations, GSK-3 has oncogenic properties. While many inhibitors to GSK-3 have been developed, their use remains controversial because of the ambiguous role of GSK-3 in cancer development. In this review, we will focus on the diverse roles that GSK-3 plays in various human cancers, in particular in solid tumors. Recently, GSK-3 has also been implicated in the generation of cancer stem cells in various cell types. We will also discuss how this pivotal kinase interacts with multiple signaling pathways such as: PI3K/PTEN/Akt/mTORC1, Ras/Raf/MEK/ERK, Wnt/beta-catenin, Hedgehog, Notch and others.

Refining the role for adult stem cells as cancer cells of origin

Significant progress has been made to identify the cells at the foundation of tumorigenesis, the cancer cell of origin (CCO). The majority of data points towards resident adult stem cells (ASCs) or primitive progenitors as the CCO for those cancers studied, highlighting the importance of stem cells not only as propagators but also as initiators of cancer. Recent data suggest tumor initiation at the CCOs can be regulated through both intrinsic and extrinsic signals and that the identity of the CCOs and their propensity to initiate tumorigenesis is context dependent. In this review, we summarize some of the recent findings regarding CCOs and solid tumor initiation and highlight its relation with bona fide human cancer.

β-catenin in oral cancer: an update on current knowledge

β-Catenin is a multiple function protein. These functions derive from its interactions with other cell proteins, both on the cell membrane, in the cytoplasm and in the nucleus. β-Catenin forms a complex with the adhesion molecule E-cadherin, promoting cell-cell adhesion and thereby preventing the cell dissociation that is required for cancer invasion and progression mechanisms. There is also a dynamic pool of cytoplasmic β-catenin that serves as connection between the extracellular microenvironment and the nucleus. Cytoplasmic β-catenin acts as a transcription factor for the nucleus in the canonical Wnt pathway, activating the transcription of various genes. Structural or functional alterations of β-catenin can promote cancer progression. This review addresses the current knowledge on the implications of β-catenin in the development of oral cancer.

KCTD1 suppresses canonical Wnt signaling pathway by enhancing β-catenin degradation

The canonical Wnt signaling pathway controls normal embryonic development, cellular proliferation and growth, and its aberrant activity results in human carcinogenesis. The core component in regulation of this pathway is β-catenin, but molecular regulation mechanisms of β-catenin stability are not completely known. Here, our recent studies have shown that KCTD1 strongly inhibits TCF/LEF reporter activity. Moreover, KCTD1 interacted with β-catenin both in vivo by co-immunoprecipitation as well as in vitro through GST pull-down assays. We further mapped the interaction regions to the 1-9 armadillo repeats of β-catenin and the BTB domain of KCTD1, especially Position Ala-30 and His-33. Immunofluorescence analysis indicated that KCTD1 promotes the cytoplasmic accumulation of β-catenin. Furthermore, protein stability assays revealed that KCTD1 enhances the ubiquitination/degradation of β-catenin in a concentration-dependent manner in HeLa cells. And the degradation of β-catenin mediated by KCTD1 was alleviated by the proteasome inhibitor, MG132. In addition, KCTD1-mediated β-catenin degradation was dependent on casein kinase 1 (CK1)- and glycogen synthase kinase-3β (GSK-3β)-mediated phosphorylation and enhanced by the E3 ubiquitin ligase β-transducin repeat-containing protein (β-TrCP). Moreover, KCTD1 suppressed the expression of endogenous Wnt downstream genes and transcription factor AP-2α. Finally, we found that Wnt pathway member APC and tumor suppressor p53 influence KCTD1-mediated downregulation of β-catenin. These results suggest that KCTD1 functions as a novel inhibitor of Wnt signaling pathway.

Jordan R. Fibro-osseous lesions of the craniofacial bones: β-catenin immunohistochemical analysis and CTNNB1 and APC mutation analysis

The canonical Wnt/β-catenin pathway is involved in the formation of craniofacial skeleton and oral tissues. Aberrant nuclear localization of β-catenin protein has been described in several human diseases including a subset of odontogenic tumors thereby suggesting an important role in tumor development. Fibro-osseous lesions of the craniofacial skeleton comprise several neoplastic, and reactive mesenchymal proliferations in which β-catenin status is unknown. To study this, we immunostained 171 fibro-osseous lesions for β-catenin protein and, for lesions with nuclear positivity, sequenced exon 3 of the CTNNB1 gene and exon 15 of the APC gene. Nuclear β-catenin immunostaining was detected in 34 (20 %) tumors with no correlation between nuclear positivity and either age, gender, or tissue decalcification status (p = 0.2, 0.17, 0.12, respectively). Absent nuclear β-catenin in fibrous dysplasia was the only diagnostically significant finding (p = 0.0034). A single point mutation at Asp56 of CTNNB1 was identified in one case of ossifying fibroma. A second ossifying fibroma and one desmoplastic fibroma demonstrated point mutations (Glu1317 and Glu1536, respectively [corrected] ) in the APC gene. These findings show that apart from fibrous dysplasia where nuclear β-catenin is rare, nuclear β-catenin staining has limited utility in discriminating among the craniofacial fibro-osseous lesions. The molecular mechanisms underlying nuclear β-catenin accumulation in the positive tumors is unlikely to be mediated by CTNNB1 exon 3 or APC exon 15 mutations in most cases.

Beta-catenin and epithelial tumors: a study based on 374 oropharyngeal cancers

Introduction. Although altered regulation of the Wnt pathway via beta-catenin is a frequent event in several human cancers, its potential implications in oral/oropharyngeal squamous cell carcinomas (OSCC/OPSCC) are largely unexplored. Work purpose was to define association between beta-catenin expression and clinical-pathological parameters in 374 OSCCs/OP-SCCs by immunohistochemistry (IHC). Materials and Methods. Association between IHC detected patterns of protein expression and clinical-pathological parameters was assessed by statistical analysis and survival rates by Kaplan-Meier curves. Beta-catenin expression was also investigated in OSCC cell lines by Real-Time PCR. An additional analysis of the DNA content was performed on 22 representative OSCCs/OPSCCs by DNA-image-cytometric analysis. Results and Discussion. All carcinomas exhibited significant alterations of beta-catenin expression (P < 0.05). Beta-catenin protein was mainly detected in the cytoplasm of cancerous cells and only focal nuclear positivity was observed. Higher cytoplasmic expression correlated significantly with poor histological differentiation, advanced stage, and worst patient outcome (P < 0.05). By Real-Time PCR significant increase of beta-catenin mRNA was detected in OSCC cell lines and in 45% of surgical specimens. DNA ploidy study demonstrated high levels of aneuploidy in beta-catenin overexpressing carcinomas. Conclusions. This is the largest study reporting significant association between beta-catenin expression and clinical-pathological factors in patients with OSCCs/OPSCCs.

Potential canonical wnt pathway activation in high-grade astrocytomas

Aberrant wnt pathway activation through cytoplasmic stabilization of β-catenin is crucial for the development of various human malignancies. In gliomagenesis, the role of canonical (i.e., β-catenin-dependent) signalling is largely unknown. Here, we studied canonical wnt pathway activation in 15 short-term cultures from high-grade gliomas and potential pathomechanisms leading to cytoplasmic β-catenin accumulation. Furthermore, we assessed the prognostic relevance of β-catenin expression in a tissue microarray comprising 283 astrocytomas. Expression of β-catenin, its transcriptional cofactors TCF-1 and TCF-4 as well as GSK-3β and APC, constituents of the β-catenin degradation complex was confirmed by RT-PCR in all cultures. A cytoplasmic β-catenin pool was detectable in 13/15 cultures leading to some transcriptional activity assessed by luciferase reporter gene assay in 8/13. Unlike other malignancies, characteristic mutations of β-catenin and APC leading to cytoplasmic stabilization of β-catenin were excluded by direct sequencing or protein truncation test. In patient tissues, β-catenin expression was directly and its degradation product's (β-catenin-P654) expression was inversely correlated with WHO grade. Increased β-catenin expression and low β-catenin-P654 expression were associated with shorter survival. Altogether, we report on potential canonical wnt pathway activation in high-grade gliomas and demonstrate that β-catenin expression in astrocytomas is associated with increased malignancy and adverse outcome.

Nuclear translocation of β-catenin synchronized with loss of E-cadherin in oral epithelial dysplasia with a characteristic two-phase appearance

AIMS

One of the important histopathological characteristics of oral epithelial dysplasia is a two-phase appearance of rete processes, comprising an upper layer of keratinized cells and a lower layer of basaloid cells, and thereby creating a sharp contrast between these two separate cell populations. The aim of this study was to determine the cellular adhesion status of the basaloid cells.

METHODS AND RESULTS

Immunohistochemistry for β-catenin, E-cadherin and their related molecules was carried out in surgical specimens of two-phase epithelial dysplasia of the oral mucosa. The lower-half basaloid cells and the upper keratinized cells were microdissected separately, and extracted DNA samples were subjected to methylation-specific polymerase chain reaction amplification for E-cadherin. β-Catenin was immunolocalized within the nuclei and cytoplasm of Ki67-positive lower-half basaloid cells, as well as on the cell membrane of upper parakeratotic cells. The basaloid cells of the lower-half were also positive for matrix metalloproteinase-7 and cyclin D1, β-catenin target gene products, α-dystroglycan, tenascin-C, and perlecan, but not for E-cadherin. The promoter region of the E-cadherin gene was hypermethylated.

CONCLUSIONS

The solid proliferation of lower-half E-cadherin-free basaloid cells is enhanced by Wnt signalling cascades, as well as by the intraepithelial extracellular matrix or its bound growth factors.

The role of the adenomatous polyposis coli (APC) in oral squamous cell carcinoma

The main cause of death in oral squamous cell carcinomas (OSCC) is metastasis. Intercellular adhesion is mediated by a family of glycoproteins called cadherins and other molecules like catenins and APC (adenomatous polyposis coli) among other. The WNT (wingless-type) gene family is a group of genes, key signaling pathway for embryonic development and oncogenesis. The goal of this paper is to describe the role of the APC gene, and its derivatives, in the carcinogenicity pathway of WNT-1, identifying its role as a tumor suppressor gene in OSCC, while describing the genetic (loss of heterozygosity and mutations) and epigenetic alterations that modulate its expression and evaluate its relationship with the clinicopathological parameters of this type of tumors. As for APC, its activity as a tumor suppressor gene appears muted on a relatively frequent basis in these tumors, either by LOH, mutations or epigenetic control mechanisms, thus resulting in a low degree of agreement between the results of different studies.

Aberrant activation of Wnt/β-catenin signaling pathway contributes to the sequential progression of DMBA-induced HBP carcinomas

Wnt signaling pathway mediated via interactions between β-catenin and members of the TCF/LEF-1 family of transcription factors plays a central role in the regulation of epithelial cell proliferation, apoptosis, differentiation, adhesion, epithelial-mesenchymal transition, and invasion. Aberrant activation of the Wnt/β-catenin signaling pathway with overexpression of Wnt and Fz, mutations of APC, β-catenin, and axin 1, and cytoplasmic accumulation of β-catenin have been frequently reported in a broad spectrum of human malignancies including oral squamous cell carcinomas (OSCCs). However, changes in the components of the Wnt signaling pathway have not been documented during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis, a paradigm for oral oncogenesis and chemointervention. In this study, we evaluated the role of β-catenin accumulation and Wnt ligands, Wnt signaling members (Fz, Dvl, APC, GSK-3β, axin, and WIF) and the downstream targets of Wnt (cyclin D1, MMP-2, and MMP-9) during the sequential progression of DMBA-induced HBP carcinomas by semi-quantitative RT-PCR and western blot analyses. Our data reveal a correlation between β-catenin accumulation and activation of Wnt signaling, and its downstream effector molecules during the sequential development of HBP carcinomas from hyperplasia to invasive carcinoma through dysplasia. Our data also support a pivotal role for β-catenin in the malignant transition of the HBP. Aberrant Wnt signaling may be a hallmark of progression to malignancy during DMBA-induced HBP carcinogenesis and could be a potential preventive and therapeutic target for suppression of OSCC.

PGE₂ targets squamous cell carcinoma cell with the activated epidermal growth factor receptor family for survival against 5-fluorouracil through NR4A2 induction

We found a linear correlation between the Prostaglandin E(2) (PGE(2)) amount and the NR4A2 expression in oral squamous cell carcinoma (SCC) tissues through a statistical analysis among 41 clinical cases. In SCC cell lines, PGE(2) receptor (EP) ligation by exogenous PGE(2) promoted the NR4A2 expression in the cAMP/protein kinase A (PKA)-dependent manner. The process required a nature of SCC cell represented by constitutive activated epidermal growth factor receptor (EGFR) family. Targeted inactivation of the EGFRs interfered the PGE(2)-dependent NR4A2 expression. The PGE(2)-dependent NR4A2 induction is essential for the resistance to anti-cancer drug-induced apoptosis especially in SCC cells which showed constitutive EGFRs activity via autocrine epiregulin, a ligand for EGFRs. Conversely, SCC cells which lack epiregulin expression in their nature could gain the ability to promote the NR4A2 expression in response to PGE(2) and attain the resistance to anti-cancer drug-induced apoptosis under the existence of exogenous epiregulin. These findings suggest that susceptibility of SCC to anti-cancer drug could be compromised when PGE(2) was delivered in the microenvironment of SCC cells supported by constitutive EGFR family activities as their nature.

Lentivirus-mediated gene silencing of beta-catenin inhibits growth of human tongue cancer cells

BACKGROUND

Beta-catenin is one of the key components of Wnt signaling pathway. Increased level of this protein has been proved to be associated with enhanced cellular proliferation and the development of many kinds of cancers. But its role in the carcinogenesis in human tongue squamous cell carcinoma, one of the most common carcinomas of the human oral cavity, remains poorly characterized.

METHODS

In this study, we used lentivirus-mediated RNA interference (RNAi) targeted against beta-catenin to determine the effects of decreasing the high constitutive level of this protein in human tongue carcinoma cell line Tca8113.

RESULTS

Our studies demonstrated that RNAi directly against beta-catenin markedly decreased beta-catenin gene expression and inhibited cellular proliferation as reflected in the reduced growth of tongue cancer cells both in vitro and in nude mice.

CONCLUSIONS

RNA interference (RNAi) targeting against beta-catenin can induce cell growth suppression of tongue cancer and may have the potential as a therapeutic modality to treat human tongue cancer.

Glycogen synthase kinase 3 beta: can it be a target for oral cancer

Despite progress in treatment approaches for oral cancer, there has been only modest improvement in patient outcomes in the past three decades. The frequent treatment failure is due to the failure to control tumor recurrence and metastasis. These failures suggest that new targets should be identified to reverse oral epithelial dysplastic lesions. Recent developments suggest an active role of glycogen synthase kinase 3 beta (GSK3 β) in various human cancers either as a tumor suppressor or as a tumor promoter. GSK3β is a Ser/Thr protein kinase, and there is emerging evidence that it is a tumor suppressor in oral cancer. The evidence suggests a link between key players in oral cancer that control transcription, accelerated cell cycle progression, activation of invasion/metastasis and anti-apoptosis, and regulation of these factors by GSK3β. Moreover, the major upstream kinases of GSK3β and their oncogenic activation by several etiological agents of oral cancer support this hypothesis. In spite of all this evidence, a detailed analysis of the role of GSK3β in oral cancer and of its therapeutic potential has yet to be conducted by the scientific community. The focus of this review is to discuss the multitude of roles of GSK3β, its possible role in controlling different oncogenic events and how it can be targeted in oral cancer.

Immunohistochemical study of β-catenin and functionally related molecular markers in tongue squamous cell carcinoma and its correlation with cellular proliferation

β-catenin plays an important role in the maintenance of cell adhesion and is a key component of the Wnt signaling pathway. However, little is known about its prognostic significance or its role in tumor progression in tongue squamous cell carcinoma (SCC). This study conducted an immunohistochemical analysis of the expression of β-catenin. Moreover, its possible correlation with clinical parameters and with the expression of the functionally related molecular markers cyclin D1 and p53 was evaluated in 50 cases of tongue SCC and 10 cases of normal tongue epithelium. The ki-67 labeling index (LI) was also examined to evaluate cellular proliferation. Our results showed a higher frequency of abnormal β-catenin expression, positive cyclin D1 and p53 expression, and a significantly higher ki-67 LI in the tongue SCC samples compared with normal tongue epithelium (P<0.05). Abnormal β-catenin and a higher ki-67 expression was significantly associated with moderately or poorly differentiated carcinoma (P<0.05). Cyclin D1-positive immunostaining showed a statistically significant association with lymph node metastasis (P<0.05). Furthermore, the abnormal expression of β-catenin significantly correlated with a higher ki-67 LI and p53 expression (P<0.05); however, there was no correlation with cyclin D1 expression (P>0.05). Taken together, our results suggest that abnormal β-catenin expression is related to the impaired cellular differentiation and proliferation involved in tumor progression in tongue SCC.

Wnt/beta-catenin signaling in oral tissue development and disease

The Wnt/beta-catenin signaling pathway is one of several key conserved intercellular signaling pathways in animals, and plays fundamental roles in the proliferation, regeneration, differentiation, and function of many cell and tissue types. This pathway is activated in a dynamic manner during the morphogenesis of oral organs, including teeth, taste papillae, and taste buds, and is essential for these processes to occur normally. Conversely, forced activation of Wnt/beta-catenin signaling promotes the formation of ectopic teeth and taste papillae. In this review, we discuss our current understanding of the roles of Wnt/beta-catenin signaling in oral tissue development and in related human diseases, and the potential of manipulating this pathway for therapeutic purposes.

Regulator of G-protein signaling (RGS) proteins in cancer biology

The regulator of G-protein signaling (RGS) family is a diverse group of multifunctional proteins that regulate cellular signaling events downstream of G-protein coupled receptors (GPCRs). In recent years, GPCRs have been linked to the initiation and progression of multiple cancers; thus, regulators of GPCR signaling are also likely to be important to the pathophysiology of cancer. This review highlights recent studies detailing changes in RGS transcript expression during oncogenesis, single nucleotide polymorphisms in RGS proteins linked to lung and bladder cancers, and specific roles for RGS proteins in multiple cancer types.

Aberrant beta-catenin expression and adenomatous polyposis coli gene mutation in ameloblastoma and odontogenic carcinoma

The Wnt pathway is involved in carcinogenesis and three regulatory genes of the Wnt pathway, APC (adenomatous polyposis coli), beta-catenin and Axin are frequently mutated in some primary human cancers. This study was conducted to clarify the relation of beta-catenin accumulation and the mutation of the CTNNB1 (beta-catenin) gene with the mutation of APC gene in the process of development of odontogenic tumors including ameloblastoma and odontogenic carcinoma (OC). beta-Catenin accumulation was examined by immunohistochemistry in formalin-fixed, paraffin-embedded samples of six ameloblastomas and eight OCs. We also performed a mutation analysis of CTNNB1 and APC to examine the cause of beta-catenin accumulation. All ameloblastoma cases and six out of eight (75%) OC cases exhibited beta-catenin accumulation in the nucleus. CTNNB1 mutation was only found in one OC case, whereas three of six (50%) ameloblastoma cases and two out of eight (25%) OC cases had APC mutations within the mutational cluster region. Our findings suggest that aberrant beta-catenin expression and APC missense mutation may play an important role for the pathogenesis of epithelial odontogenic tumors.

Evaluation of a variant in the transcription factor 7-like 2 (TCF7L2) gene and prostate cancer risk in a population-based study

BACKGROUND

Transcription factor 7-like 2 (TCF7L2) is a high mobility group-box containing protein that is a critical member of the Wnt/beta-catenin canonical signaling pathway. In addition to its recently recognized role in diabetes, aberrant TCF7L2 expression has been implicated in cancer through regulation of cell proliferation and apoptosis by c-MYC and cyclin D. It has been hypothesized that germline variants within the TCF7L2 gene previously associated with diabetes may affect cancer risk through the Wnt/beta-catenin signaling pathway. Specifically, the same risk allele of single nucleotide polymorphism (SNP) rs12255372 that is associated with diabetes (T allele) has recently been associated with an increased risk of breast cancer.

METHODS

Here, we investigated associations between rs12255372 and prostate cancer risk among 1,457 cases and 1,351 controls from a population-based study.

RESULTS

The variant TT genotype was not associated with overall prostate cancer risk. However, there was evidence that men homozygous for the variant T allele had an elevated relative risk of more aggressive prostate cancer, as defined by high Gleason score (OR = 1.7, 95% CI = 1.0-2.8) or regional/distant stage (OR = 1.7, 95% CI = 1.1-2.6) disease.

CONCLUSIONS

Our findings suggest that this variant in the TCF7L2 gene may be associated with risk of developing more clinically significant disease. These results need to be confirmed, but provide initial evidence that the TCF7L2 gene may alter risk of developing more aggressive prostate cancer.

Altered expression of desmocollin 3, desmoglein 3, and beta-catenin in oral squamous cell carcinoma: correlation with lymph node metastasis and cell proliferation

Desmocollin 3 (Dsc3) and desmoglein 3 (Dsg3) are both transmembrane glycoproteins that belong to the cadherin family of calcium-dependent cell adhesion molecules. beta-Catenin is a member of the cadherin-catenin complex that mediates homotypic cell-cell adhesion and is also an important molecule in the wnt signaling pathway. In this study, we examined the simultaneous expression level of Dsc3, Dsg3, and beta-catenin in oral squamous cell carcinomas (OSCCs) and normal oral epithelia using immunohistochemistry. There was a significant correlation (p < 0.05) among the following variables in OSCCs: reduced or loss of expression of Dsc3, Dsg3, and beta-catenin compared to normal oral epithelium, reduced or loss of expression of Dsc3 and histological grade (moderately or poorly differentiated), and reduced or loss of expression of beta-catenin and lymph node metastasis. Furthermore, a positive correlation was found between reduced or loss of beta-catenin staining and reduced or loss of Dsc3 staining in lymph node metastatic cancer tissue (r = 0.734, p < 0.05). These results suggest an abnormal expression of Dsc3, Dsg3, and beta-catenin induced in the progression of oral carcinomas and that the Dsc3 expression level might be related to the regulation of beta-catenin in lymph node metastasis and cell proliferation in OSCCs.