The upregulation of insulin-like growth factor-1 in oral submucous fibrosis

Comparison of Immunohistochemical Markers in Oral Submucous Fibrosis and Oral Submucous Fibrosis Transformed to Oral Squamous Cell Carcinoma-A Systematic Review and Meta-Analysis

The objective of the study was to compare the expression of immunohistochemical (IHC) markers of oral submucous fibrosis (OSMF) (non-transformed group) to those of oral squamous cell carcinoma (OSCC) transformed from OSMF (transformed group). The search for comparative cross-sectional studies was carried out in PubMed and Scopus abiding to the PICO criteria, where expression of IHC markers in OSMF were compared with that of OSCC transformed from OSMF. The cellular distribution, number of positive cases, staining intensity, and mean immunoreactive score (IRS) of each IHC marker were evaluated in both groups. A total of 14 studies were included in the systematic review, in which immunoexpression of 15 epithelial and 4 connective tissue biomarkers were evaluated. Expression of β1-integrin, OCT-3, CD1a, CD207, survivin, Dickkopf-1, COX-2, hTERT, CTGF, MDM2, Ki-67, and α-SMA were increased during transformation of OSMF to OSCC. Conversely, expression of PTEN and lysyl oxidase decreased during transformation of OSMF to OSCC. Expression of a group of epithelial markers, such as COX2, hTERT, CTGF, survivin, MDM2, and p53, was 38 times lower in the non-transformed group cases compared to transformed group cases (95% CI: 58% to 10%; p = 0.01; and I² = 90%). Meta-analysis of all markers involved in cell metabolism/apoptosis, which included β1-integrin along with the above markers also suggested 42 times lower expression in the non-transformed group as compared to the transformed group (95% CI: 58% to 10%; p = 0.01; and I² = 90%). Sub-group analyses on cytoplasmic and nuclear epithelial markers were inconclusive. Meta-analysis of connective tissue markers was also inconclusive. No publication bias was found. Instead of delving into numerous markers without a strong basis for their use, it is advisable to further study the markers identified in this study to explore their clinical utility.

Lifestyle, Insulin Resistance and Semen Quality as Co-Dependent Factors of Male Infertility

Infertility is a problem that affects millions of couples around the world. It is known as a disease of couples, not individuals, which makes diagnosis difficult and treatment unclear. Male infertility can have many causes, from mechanical ones to abnormal spermatogenesis or spermiogenesis. Semen quality is determined by a number of factors, including those dependent on men themselves, with the number of infertile men growing every year. These include, e.g., diet, physical activity, sleep quality, stress, among many others. As these factors co-exist with insulin resistance, which is a disease closely related to lifestyle, it has been singled out in the study due to its role in affecting semen quality. In order to examine connections between lifestyle, insulin resistance, and semen quality, a review of literature published from 1989 to 2020 in the following databases PubMed/Medline, EMBASE (Elsevier), Scopus, Web of Science, and Google Scholar was performed. Hence, semen quality, environment, and insulin resistance are interrelated, thus it is difficult to indicate which aspect is the cause and which is the effect in a particular relationship and the nature of possible correlations. Since the influence of lifestyle on semen quality has been extensively studied, it is recommended that more thorough research be done on the relationship between insulin resistance and semen quality, comparing the semen quality of men with and without insulin resistance.

Arecoline Enhances Phosphodiesterase 4A Activity to Promote Transforming Growth Factor-β-Induced Buccal Mucosal Fibroblast Activation via cAMP-Epac1 Signaling Pathway

Chewing areca nut (betel quid) is strongly associated with oral submucous fibrosis (OSF), a pre-cancerous lesion. Among the areca alkaloids, arecoline is the main agent responsible for fibroblast proliferation; however, the specific molecular mechanism of arecoline affecting the OSF remains unclear. The present study revealed that arecoline treatment significantly enhanced Transforming growth factor-β (TGF-β)-induced buccal mucosal fibroblast (BMF) activation and fibrotic changes. Arecoline interacts with phosphodiesterase 4A (PDE4A) to exert its effects through modulating PDE4A activity but not PDE4A expression. PDE4A silence reversed the effects of arecoline on TGF-β-induced BMFs activation and fibrotic changes. Moreover, the exchange protein directly activated by cAMP 1 (Epac1)-selective Cyclic adenosine 3′,5′-monophosphate (cAMP) analog (8-Me-cAMP) but not the protein kinase A (PKA)-selective cAMP analog (N6-cAMP) remarkably suppressed α-smooth muscle actin(α-SMA) and Collagen Type I Alpha 1 Chain (Col1A1) protein levels in response to TGF-β1 and arecoline co-treatment, indicating that cAMP-Epac1 but not cAMP-PKA signaling is involved in arecoline functions on TGF-β1-induced BMFs activation. In conclusion, arecoline promotes TGF-β1-induced BMFs activation through enhancing PDE4A activity and the cAMP-Epac1 signaling pathway during OSF. This novel mechanism might provide more powerful strategies for OSF treatment, requiring further in vivo and clinical investigation.

Oral submucous fibrosis stimulates invasion and epithelial-mesenchymal transition in oral squamous cell carcinoma by activating MMP-2 and IGF-IR

Oral submucous fibrosis (OSF) involves a high risk of malignant transformation and has been implicated in oral cancer. Limited studies have been conducted on the role of OSF in relation to the invasive capabilities and epithelial-mesenchymal transition (EMT) in oral cancer. Herein, we investigated the effects of OSF on the microenvironment of human oral cancer cells. The results showed that the conditioned medium (CM) of fibrotic buccal mucosal fibroblasts (fBMFs) strongly induced the invasion of oral cancer cells and increased the activities of matrix metalloproteinase-2. OSF significantly induced the EMT in oral cancer cells and downregulated epithelial markers, such as E-cadherin, but significantly elevated vimentin, fibronectin, N-cadherin, RhoA, Rac-1 and FAK. Insulin-like growth factor-1 (IGF-1) was elevated in OSF. The protein levels of the IGF-1R were upregulated specifically in fBMF CM treatment for oral cancer cells, and the IGFR gene was confirmed by The Cancer Genome Atlas patient transcriptome data. The Kaplan-Meier curve analysis revealed that patients with oral squamous cell carcinoma and high IGFR expression levels had poorer 5-year survival than those with low IGFR expression (p = 0.004). The fBMF-stimulated EMT cell model may recapture some of the molecular changes during EMT progression in clinical patients with oral cancer.

Emerging role of cellular senescence in the pathogenesis of oral submucous fibrosis and its malignant transformation

Senescence is a common denominator in wound healing, fibrosis, and cancer. Although, senescence is transiently antifibrotic, when prolonged, promotes fibrosis and malignant transformation. Eligible studies indexed in MEDLINE, Embase and Web of Science were searched to understand the role of cellular senescence in the pathogenesis of oral submucous fibrosis (OSF) and its malignant transformation. The senescence-associated secretory phenotype (SASP) components like IL-1, IL-6, and GRO-α induce double-strand DNA breaks in keratinocytes and drive genetic instability. SASP derived from myofibroblasts induces epithelial-mesenchymal transition in OSF and facilitates cancer progression. The use of senolytics has been shown to eliminate senescent cells from the areas of fibrosis, thereby preventing malignancy. Naturally occurring agents such as apigenin and kaempferol inhibit SASP. Mechanistic insight into the emerging role of senescence in the pathogenesis of OSF and modalities to inhibit senescence-associated antiapoptotic pathways as a supplementary therapy to prevent malignant transformation of OSF is underlined.

Areca Nut Chewing: Initiation, Addiction, and Harmful Effects Emphasizing the Barriers and Importance of Cessation

Areca nut is a highly addictive substance with carcinogenic properties and causes many harmful effects to the human body. Alkaloids are the major chemicals found in areca nut, and their mechanism of action has been studied for several years. About 600 million people around the world use areca nut, and its usage is higher in Asian countries. Areca nut chewers get used to the habit mainly due to social influence, stress, or lack of awareness. Some studies have reported a dependence syndrome related to areca nut chewing. Even though there are many ongoing research studies regarding tobacco addiction, less concern has been given to the areca nut addiction. There are only few studies related to areca nut cessation, and even those few cessation programs are mainly designed using tobacco cessation methodology. Sociocultural influence, behavioral factors, and accessibility are the main barriers to cessation. Behavior changing interventions proved to be more effective in areca nut cessation, but recently studies on pharmacological therapies are also emerging.

Genome-wide DNA methylation changes in oral submucous fibrosis

OBJECTIVE

Oral submucous fibrosis (OSF) is a debilitating potentially malignant condition of the buccal cavity characterized by extensive extracellular matrix deposition resulting in stiffness and trismus. As OSF is a progressive disease, we hypothesized that there would be extensive epigenetic changes in OSF tissues.

MATERIALS AND METHODS

Using the Infinium HumanMethylation450 BeadChip Array, we analyzed gross DNA methylation changes in seven OSF tissues compared to five controls. Comparison with transcriptomic data and pathway analyses was conducted to find commonly regulated genes.

RESULTS

A total of 3,294 differentially methylated regions mapping to 857 genes were identified. Comparison with transcriptome data revealed 38 downregulated-hypermethylated genes and 55 hypomethylated-upregulated genes. Using methylation-specific and qRT-PCR, aberrant hypomethylation and increased expression of FGF13, RPS6KA3, and ACSL4 genes were confirmed. Pathways involved in insulin signaling, ubiquitin-mediated proteolysis, nicotine addiction, and RAS/MAPK pathways were dysregulated, among others. Intriguingly, numerous genes located on the X chromosome were dysregulated in OSF tissues as the transcript for XIST gene was downregulated due to hypermethylation of the XIST promoter.

CONCLUSIONS

This study highlights global epigenetic dysregulation of tissues of the oral cavity in OSF patients and hints at possible X chromosomal dysregulation, previously not implicated in the pathogenesis of OSF.

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.

Signaling pathways promoting epithelial mesenchymal transition in oral submucous fibrosis and oral squamous cell carcinoma

Epithelial-mesenchymal transition (EMT) is a critical process that occurs during the embryonic development, wound healing, organ fibrosis and the onset of malignancy. Emerging evidence suggests that the EMT is involved in the invasion and metastasis of cancers. The inflammatory reaction antecedent to fibrosis in the onset of oral submucous fibrosis (OSF) and the role of EMT in its malignant transformation indicates a hitherto unexplored involvement of EMT. This review focuses on the role of EMT markers which are regulators of the EMT mediated complex network of molecular mechanisms involved in the pathogenesis of OSF and OSCC. Further the gene enrichment analysis and pathway analysis supports the association of the upregulated and downregulated genes in various EMT regulating pathways.

Proteomic Analysis Reveals Anti-Fibrotic Effects of Blue Light Photobiomodulation on Fibroblasts

BACKGROUND AND OBJECTIVES

This study was aimed at determining the effects of blue light photobiomodulation on primary adult mouse dermal fibroblasts (AMDFs) and the associated signaling pathways.

STUDY DESIGN/MATERIALS AND METHODS

Cultured AMDFs from adult C57BL/6 mice were irradiated by blue light from a light-emitting diode (wavelength = 463 ± 50 nm; irradiance = 5 mW/cm² ; energy density = 4-8 J/cm² ). The cells were analyzed using mass spectrometry for proteomics/phosphoproteomics, AlamarBlue assay for mitochondrial activity, time-lapse video for cell migration, quantitative polymerase chain reaction for gene expression, and immunofluorescence for protein expression.

RESULTS

Proteomic/phosphoproteomic analysis showed inhibition of extracellular signal-regulated kinases/mammalian target of rapamycin and casein kinase 2 pathways, cell motility-related networks, and multiple metabolic processes, including carbon metabolism, biosynthesis of amino acid, glycolysis/gluconeogenesis, and the pentose phosphate pathway. Functional analysis demonstrated inhibition of mitochondrial activities, cell migration, and mitosis. Expression of growth promoting insulin-like growth factor 1 and fibrosis-related genes, including transforming growth factor β1 (TGFβ1) and collagen type 1 ɑ2 chain diminished. Protein expression of α-smooth muscle actin, an important regulator of myofibroblast functions, was also suppressed.

CONCLUSIONS

Low-level blue light exerted suppressive effects on AMDFs, including suppression of mitochondrial activity, metabolism, cell motility, proliferation, TGFβ1 levels, and collagen I production. Low-level blue light can be a potential treatment for the prevention and reduction of tissue fibrosis, such as hypertrophic scar and keloids. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Survivin and insulin-like growth factor-I: potential role in the pathogenesis of acne and post-acne scar

BACKGROUNDS/OBJECTIVES

Acne is an inflammatory disease of the pilosebaceous unit (PSU). The over-expression of survivin and insulin-like growth factor (IGF)-I in some fibrotic disorders suggests a possible implication in the pathogenesis of acne and or post-acne scar. We aimed to evaluate their potential role in pathogenesis in acne and post-acne scar.

METHODS

Serum survivin and IGF-I levels were estimated in 30 patients with acne and post-acne scar compared to 30 controls.

RESULTS

There was a statistically significant difference in survivin and IGF-I levels between controls and patients (P < 0.05). However, there was no linear correlation between survivin and IGF-I.

CONCLUSIONS

Survivin and IGF-I could have a possible role in the pathogenesis of active acne and in post-inflammatory acne scar.

The role of myofibroblasts in the progression of oral submucous fibrosis: A systematic review

Oral Submucous Fibrosis (OSMF) is a chronic progressive scarring oral disease predominantly affecting people of South Asian origin. It is characterized by juxtaepithelial inflammatory cell infiltration followed by fibrosis in the lamina propria and submucosa of the oral mucosa. The pathogenesis of the disease is not well established and a number of mechanisms have been proposed regarding the pathogenesis. A renewed interest has been shown in myofibrobasts which have been implicated to play a significant role in the pathogenesis of OSMF. The myofibroblast were initially identified by means of electron microscopy in granulation tissue of healing wounds as a modulated fibroblast exhibiting features of smooth muscle cells, with prominent bundles of microfilaments, dense bodies scattered in between, and gap junctions. The presence of myofibroblasts has successively been described in practically all fibrotic situations characterized by tissue retraction and remodeling. This review paper is an attempt to identify all the studies involving myofibroblasts and explaining the pathogenesis in a simplified manner.

Regulation of hypoxia-inducible factor-1α in human buccal mucosal fibroblasts stimulated with arecoline

Hypoxia-inducible factor (HIF)-1α is consistently and dramatically upregulated in a variety of fibrotic diseases. The aim of this study was to compare HIF-1α expression from fibroblasts derived from human normal buccal mucosa and oral submucous fibrosis (OSF) specimens and further to explore the potential mechanisms that may lead to induce HIF-1α expression. OSF buccal mucosal fibroblasts (BMFs) demonstrated significantly higher HIF-1α mRNA expression than normal BMFs (p<0.005). Arecoline, the major areca nut alkaloid, was also found to elevate HIF-1α mRNA expression in a dose-dependent manner (p<0.05). Moreover, arecoline-induced HIF-1α expression was downregulated by mitogen-activated protein kinase inhibitor U0126, phosphatidylinositol 3-kinase inhibitor LY294002, p38 inhibitor SB203580, cyclooxygenase-2 inhibitor NS-398, and glutathione precursor N-acetyl-L-cysteine (p<0.05). Taken together, hypoxia plays an important role in the pathogenesis of areca quid chewing-associated OSF. These pharmacological agents may be further used as chemoprevention agents for OSF.

Aberrant SSEA-4 upregulation mediates myofibroblast activity to promote pre-cancerous oral submucous fibrosis

Oral submucous fibrosis (OSF), regarded as a precancerous condition, is characterized by juxta-epithelial inflammatory reaction followed by fibro-elastic change in the lamina properia and epithelial atrophy. The pathologic mechanisms of OSF still need to be further clarified. In the study, we investigated the functional expression of SSEA-4, which is a well-known stemness marker, in myofibroblast activity and the clinical significance in OSF tissues. The expression of SSEA-4 in OSF was evaluated by immunohistochemical staining. Functional analysis of SSEA-4 on myofibroblast activity of OSF was achieved by lentiviral silencing ST3GAL2. Immunohisitochemistry demonstrated that SSEA-4 expression was significantly higher expression in areca quid chewing-associated OSF tissues than those of normal oral mucosa tissues. From flow cytometry analysis, arecoline dose-dependently activated SSEA-4 expression in primary human normal buccal mucosal fibroblasts (BMFs). Sorted SSEA-4-positive cells from fibrotic BMFs (fBMFs) have higher colony-forming unit, collagen gel contraction, and α-smooth muscle actin (α-SMA) expression than SSEA-4-negative subset. Knockdown of ST3GAL2 in fBMFs suppressed SSEA-4 expression, collagen contraction, migration, invasiveness, and wound healing capability. Consistently, silencing ST3GAL2 was found to repress arecoline-induced myofibroblast activity in BMFs. The study highlights SSEA-4 as a critical marker for therapeutic intervention to mediate myofibroblast transdifferentiation in areca quid chewing-associated OSF.

Survivin as a Novel Biomarker in the Pathogenesis of Acne Vulgaris and Its Correlation to Insulin-Like Growth Factor-I

Survivin, a member of the inhibitor of apoptosis protein family, has an important role in cell cycle regulation. Insulin-like growth factor-I (IGF-I) is a polypeptide hormone with wide range of biologic effects including stimulation of lipogenesis in sebaceous glands. Their overexpression in some fibrotic disorders suggests a possible implication of both IGF-I and survivin in the pathogenesis of acne and/or acne scars. The current study aimed to assess and correlate serum levels of IGF-I and survivin in patients with active acne vulgaris and postinflammatory acne scars and to evaluate their lesional expressions in comparison to healthy controls. Serum IGF-I and survivin were estimated using commercially available ELISA kits and their tissues expressions were investigated using Western blotting. Our findings suggest that IGF-I and survivin could play potential roles in the pathogenesis of active acne vulgaris and more importantly in postinflammatory acne scars with significant positive correlation coefficient between serum levels of IGF-I and survivin which support IGF-I-/PI3K-/AKT-mediated downregulation of nuclear expression of FoxO transcription factors resulting in enhanced survivin expression.

Epithelial atrophy in oral submucous fibrosis is mediated by copper (II) and arecoline of areca nut

Exposure of oral cavity to areca nut is associated with several pathological conditions including oral submucous fibrosis (OSF). Histopathologically OSF is characterized by epithelial atrophy, chronic inflammation, juxtaepithelial hyalinization, leading to fibrosis of submucosal tissue and affects 0.5% of the population in the Indian subcontinent. As the molecular mechanisms leading to atrophied epithelium and fibrosis are poorly understood, we studied areca nut actions on human keratinocyte and gingival fibroblast cells. Areca nut water extract (ANW) was cytotoxic to epithelial cells and had a pro-proliferative effect on fibroblasts. This opposite effect of ANW on epithelial and fibroblast cells was intriguing but reflects the OSF histopathology such as epithelial atrophy and proliferation of fibroblasts. We demonstrate that the pro-proliferative effects of ANW on fibroblasts are dependent on insulin-like growth factor signalling while the cytotoxic effects on keratinocytes are dependent on the generation of reactive oxygen species. Treatment of keratinocytes with arecoline which is a component of ANW along with copper resulted in enhanced cytotoxicity which becomes comparable to IC(50) of ANW. Furthermore, studies using cyclic voltammetry, mass spectrometry and plasmid cleavage assay suggested that the presence of arecoline increases oxidation reduction potential of copper leading to enhanced cleavage of DNA which could generate an apoptotic response. Terminal deoxynucleotidyl transferase dUTP Nick End Labeling assay and Ki-67 index of OSF tissue sections suggested epithelial apoptosis, which could be responsible for the atrophy of OSF epithelium.

Elevation of Twist expression by arecoline contributes to the pathogenesis of oral submucous fibrosis

BACKGROUND/PURPOSE

Oral submucous fibrosis (OSF), a chronic progressive scarring disease, has been considered as a precancerous condition of oral mucosa. In this study, we investigated the functional role of Twist, an epithelial-mesenchymal transition (EMT) transcriptional factor, in myofibroblastic differentiation activity of OSF.

METHODS

Arecoline, a major areca nut alkaloid, was used to explore whether expression of Twist could be changed dose-dependently in human primary buccal mucosal fibroblasts (BMFs). Collagen gel contraction and migration capability in arecoline-stimulated BMFs and primary oral submucous fibrosis-derived fibroblasts (OSFs) with Twist knockdown was presented.

RESULTS

We observed that the treatment of arecoline dose-dependently increased Twist expression transcript and protein levels in BMFs. The myofibroblast activity including collagen gel contraction and migration capability also induced by arecoline, while knockdown of Twist reversed these phenomena. Importantly, inhibition of Twist led to the suppression collagen contraction and wound healing capability of primary cultivated OSFs. Clinically, Twist transcript and protein expression was higher in areca quid chewing-associated OSF tissues than in normal oral mucosa tissues.

CONCLUSION

This evidence suggests that upregulation of Twist might be involved in the pathogenesis of areca quid-associated OSF through dysregulation of myofibroblast activity.

Oral submucous fibrosis: an update

Oral submucous fibrosis (OSF) is a premalignant condition caused by betel chewing. It is very common in Southeast Asia but has started to spread to Europe and North America. OSF can lead to squamous cell carcinoma, a risk that is further increased by concomitant tobacco consumption. OSF is a diagnosis based on clinical symptoms and confirmation by histopathology. Hypovascularity leading to blanching of the oral mucosa, staining of teeth and gingiva, and trismus are major symptoms. Major constituents of betel quid are arecoline from betel nuts and copper, which are responsible for fibroblast dysfunction and fibrosis. A variety of extracellular and intracellular signaling pathways might be involved. Treatment of OSF is difficult, as not many large, randomized controlled trials have been conducted. The principal actions of drug therapy include antifibrotic, anti-inflammatory, and antioxygen radical mechanisms. Potential new drugs are on the horizon. Surgery may be necessary in advanced cases of trismus. Prevention is most important, as no healing can be achieved with available treatments.

ZEB1 as an indicator of tumor recurrence for areca quid chewing-associated oral squamous cell carcinomas

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the sixth most prevalent malignancy worldwide and the third most common cancer in developing nation. Most OSCC patients relapse within months after receiving treatment. Therefore, searching the biomarkers of recurrence is urgently required to improve OSCC patient survival.

METHODS

We set out to explore whether expression of ZEB1 could be triggered in oral epithelial cells (SG and FaDu) by arecoline in vitro. Control and ZEB1-knockdown arecoline-stimulated SG and FaDu were subjected to migration/invasiveness/anchorage-independent growth assay. Primary and recurrent OSCC tissues from areca quid chewers were analyzed using real-time RT-PCR analysis for ZEB1 expression.

RESULTS

Arecoline led to dose-dependent elevation of ZEB1 expression in SG and FaDu cells. Downregulation of ZEB1 by lentiviral infection significantly reversed arecoline-induced oncogenicity including migration ability, cell invasiveness, and anchorage-independent growth in SG and FaDu cells. Clinically, the level of ZEB1 expression was higher in recurrent OSCC tumor samples but lower in primary lesions.

CONCLUSIONS

Targeting ZEB1 might offer a new strategy for the treatment of OSCC patients. ZEB1 can serve as a progression and relapse marker in OSCC patients.

Hypoxic regulation of plasminogen activator inhibitor-1 expression in human buccal mucosa fibroblasts stimulated with arecoline

BACKGROUND

Oral submucous fibrosis (OSF) is regarded as a pre-cancerous condition with fibrosis in oral subepithelial connective tissue. Hypoxia-inducible factor (HIF)-1α regulates a wide variety of profibrogenic genes, which are closely associated with tissue fibrosis. The aim of this study was to compare HIF-1α expression in normal buccal mucosa tissues and OSF specimens and further explore the potential mechanisms that may lead to the induction of HIF-1α expression.

METHOD

Twenty-five OSF specimens and six normal buccal mucosa were examined by immunohistochemistry. The expression of HIF-1α from fibroblasts cultured from OSF and normal buccal mucosa was measured by Western blot. Arecoline, a major areca nut alkaloid, was challenged to normal buccal mucosa fibroblasts (BMFs) to elucidate whether HIF-1α expression could affect by arecoline. In addition, the effects of arecoline on plasminogen activator inhibitor (PAI)-1 expression were evaluated in environmental hypoxia.

RESULTS

HIF-1α expression was significantly higher in OSF specimens and expressed mainly by fibroblasts, epithelial cells, and inflammatory cells. Fibroblasts derived from OSF were found to exhibit higher HIF-1α protein expression than BMFs (P < 0.05). Arecoline was found to upregulate HIF-1α protein in a dose-dependent manner (P < 0.05). Hypoxia increased arecoline-induced PAI-1 protein expression than normoxic conditions (P < 0.05).

CONCLUSION

These results suggest that HIF-1α expression is significantly upregulated in OSF tissues from areca quid chewers, implying a potential role as a biomarker for local tissue hypoxia. The activation of HIF-1α may promote fibrogenesis by an increase of PAI-1 expression and a subsequent elevation of extracellular matrix production in oral submucosa leading to fibrosis.

Arecoline-induced myofibroblast transdifferentiation from human buccal mucosal fibroblasts is mediated by ZEB1

Oral submucous fibrosis (OSF) is considered as a pre-cancerous condition of the oral mucosa and is highly associated with habitual areca quid chewing. Arecoline is the major alkaloid in areca quid and is thought to be involved in the pathogenesis of OSF. Our previous studies have demonstrated that arecoline could induce epithelial–mesenchymal transition (EMT)-related factors in primary human buccal mucosal fibroblasts (BMFs). Therefore, we investigated the expression of zinc finger E-box binding homeobox 1 (ZEB1), which is a well-known transcriptional factor in EMT, in OSF tissues and its role in arecoline-induced myofibroblast transdifferentiation from BMFs. The expression of ZEB1, as well as the myofibroblast marker α-smooth muscle actin (α-SMA), was significantly increased in OSF tissues, respectively. With immunofluorescence analysis, arecoline induced the formation of α-SMA-positive stress fibres in BMFs expressing nuclear ZEB1. Arecoline also induced collagen contraction of BMFs in vitro. By chromatin immunoprecipitation, the binding of ZEB1 to the α-SMA promoter in BMFs was increased by arecoline. The promoter activity of α-SMA in BMFs was also induced by arecoline, while knockdown of ZEB1 abolished arecoline-induced α-SMA promoter activity and collagen contraction of BMFs. Long-term exposure of BMFs to arecoline induced the expression of fibrogenic genes and ZEB1. Silencing of ZEB1 in fibrotic BMFs from an OSF patient also suppressed the expression of α-SMA and myofibroblast activity. Inhibition of insulin-like growth factor receptor-1 could suppress arecoline-induced ZEB1 activation in BMFs. Our data suggest that ZEB1 may participate in the pathogenesis of areca quid–associated OSF by activating the α-SMA promoter and inducing myofibroblast transdifferentiation from BMFs.

Elevation of S100A4 expression in buccal mucosal fibroblasts by arecoline: involvement in the pathogenesis of oral submucous fibrosis

Background

S100A4, a member of the calcium-binding proteins, is dramatically elevated in a variety of fibrotic diseases. Areca quid chewing is the most important etiological factor in the pathogenesis of oral submucous fibrosis (OSF). OSF has been considered as a pre-cancerous condition of oral mucosa. The aim of this study was to determine the critical role of S100A4 expression in the pathogenesis of OSF both in vitro and in vivo.

Methodology/Principal Finding

Thirty OSF tissues from areca quid chewers and ten normal buccal mucosa samples without areca quid chewing were analyzed by using immunohistochemistry for S100A4 expression in vivo. Collagen gel contraction capability and expression of tissue inhibitor of metalloproteinases 1 (TIMP1)/MMP9 in arecoline-stimulated BMFs with S100A4 knockdown was presented in vitro. Initially, S100A4 expression was higher in areca quid chewing-associated OSF specimens than normal buccal mucosa specimens (p = 0.001). Arecoline, a major areca nut alkaloid, led to dose- and time-dependent elevation of S100A4 expression in normal buccal mucosa fibroblasts BMFs (p<0.05). The additions of pharmacological agents rapamycin (mTOR inhibitor), PD98059 (ERK inhibitor), and Bay117082 (NF-κB inhibitor) were found to inhibit arecoline-induced S100A4 expression (p<0.05) in BMFs. Down-regulation of S100A4 by lentiviral infection significantly reversed arecoline-induced collagen gel contraction and TIMP1/MMP9 expression.

Conclusion/Significance

These results suggest that S100A4 expression is significantly up-regulated in OSF specimens. Arecoline-induced S100A4 expression was down-regulated by rapamycin, PD98059, and Bay117082. Targeting S100A4 might be a potential therapeutic target for OSF through TIMP1/MMP9 down-regulation.

Regulation of protease-activated receptor-1 expression in human buccal fibroblasts stimulated with arecoline

BACKGROUND

The purpose of this study was to compare the major thrombin receptor protease-activated receptor-1 (PAR-1) expression in normal human buccal mucosa and oral submucous fibrosis (OSF) specimens and further explore the potential mechanisms that may lead to induce PAR-1 expression.

METHODS

Thirty OSF and 10 normal buccal mucosa specimens were examined by immunohistochemistry. Buccal mucosal fibroblasts (BMFs) were challenged with arecoline by using Western blot analysis. N-acetyl-L-cysteine (NAC), LY294002, herbimycin A, NS-398, and PD98059 were added to find the possible regulatory mechanisms.

RESULTS

PAR-1 expression was significantly higher in OSF specimens (p < .05). Arecoline was found to elevate PAR-1 expression in a dose-dependent and time-dependent manner (p < .05). The addition of NAC, LY294002, herbimycin A, NS398, and PD98059 markedly inhibited the arecoline-induced PAR-1 expression (p < .05).

CONCLUSION

PAR-1 expression is significantly upregulated in areca quid chewing-associated OSF. Arecoline-induced PAR-1 expression was downregulated by NAC, LY294002, herbimycin A, NS398, and PD98059.

Association of betel nut with carcinogenesis: revisit with a clinical perspective

Betel nut (BN), betel quid (BQ) and products derived from them are widely used as a socially endorsed masticatory product. The addictive nature of BN/BQ has resulted in its widespread usage making it the fourth most abused substance by humans. Progressively, several additives, including chewing tobacco, got added to simple BN preparations. This addictive practice has been shown to have strong etiological correlation with human susceptibility to cancer, particularly oral and oropharyngeal cancers.

The PUBMED database was searched to retrieve all relevant published studies in English on BN and BQ, and its association with oral and oropharyngeal cancers. Only complete studies directly dealing with BN/BQ induced carcinogenesis using statistically valid and acceptable sample size were analyzed. Additional relevant information available from other sources was also considered.

This systematic review attempts to put in perspective the consequences of this widespread habit of BN/BQ mastication, practiced by approximately 10% of the world population, on oral cancer with a clinical perspective. BN/BQ mastication seems to be significantly associated with susceptibility to oral and oropharyngeal cancers. Addition of tobacco to BN has been found to only marginally increase the cancer risk. Despite the widespread usage of BN/BQ and its strong association with human susceptibility to cancer, no serious strategy seems to exist to control this habit. The review, therefore, also looks at various preventive efforts being made by governments and highlights the multifaceted intervention strategies required to mitigate and/or control the habit of BN/BQ mastication.

Quercetin in elimination of tumor initiating stem-like and mesenchymal transformation property in head and neck cancer

BACKGROUND

Previously, we enriched a subpopulation of head and neck cancer-derived tumor initiating cells (HNC-TICs) presented high tumorigenic, chemo-radioresistant, and coupled with epithelial-mesenchymal transition (EMT) properties. The purpose of this study was to investigate the therapeutic effect and molecular mechanisms of quercetin on HNC-TICs.

METHOD

ALDH1 activity of head and neck cancer cells with quercetin treatment was assessed by the Aldefluor assay flow cytometry analysis. Self-renewal, invasiveness, and EMT capability of HNC-TICs with different doses of quercetin was presented.

RESULTS

We first observed that the treatment of quercetin significantly downregulated the ALDH1 activity of head and neck cancer cells in a dose-dependent manner (p < .05). Moreover, quercetin reduced self-renewal property and stemness signatures expression in head and neck cancer-derived sphere cells. The migration ability of head and neck cancer-derived sphere cells was lessened under quercetin treatment partially due to the decreased productions of Twist, N-cadherin, and vimentin.

CONCLUSION

Quercetin suppressing HNC-TICs characteristics may therefore be valuable therapeutics clinically in combination with standard treatment modalities.

Areca nut in pathogenesis of oral submucous fibrosis: revisited

BACKGROUND

Oral submucous fibrosis is a disease due to a chronic, insidious change in fibro-elasticity, characterized by burning sensation in the oral cavity, blanching, and stiffening of the oral mucosa and oropharynx leading to trismus and inability to open the mouth. The symptoms and signs depend on the progression of the lesions and number of affected sites. It is predominantly seen in Indians and other Asians. Once the disease has developed, there is neither regression nor any effective treatment. It is considered as a pre-malignant stage of oral cancer, and the reported risk of malignant transformation varies from 2.3-7.6%.

CONCLUSIONS

The common etiological factor considered for this unremitting disease is use of areca nut; however, the precise mechanism still remains elusive and controversial. A wide range of treatment consisting of drugs, surgical therapy, and physiotherapy have been attempted till date, with varying degrees of benefit, but none of them have proved to be a cure for this disease. This field remains open for clinical trials and research. This paper aims to give an overview on the role of areca nut in the pathogenesis and malignant potential of oral submucous fibrosis.

Management of oral submucous fibrosis: an overview

Oral submucous fibrosis is a disease due to a chronic, insidious change in fibroelasticity, characterized by burning sensation in the oral cavity, blanching, and stiffening of the oral mucosa and oro-pharynx leading to trismus and inability to open the mouth. The symptoms and signs depend on the progression of the lesions and number of affected sites. It is predominantly seen in Indians and other Asians. Once, the disease has developed, there is neither regression nor any effective treatment. It is considered as a pre-malignant stage of oral cancer and reported risk of malignant transformation varies from 2.3-7.6%.The common etiological factor considered for this unremitting disease is use of areca nut; however, the precise pathogenesis still remains elusive and controversial. A wide range of treatment consisting of drug management, surgical therapy, and physiotherapy have been attempted till date; with varying degrees of benefit, but none of them have proved to be a cure for this disease. This field remains open for clinical trials and research. This paper aims to provide an overview on various management modalities available for oral submucous fibrosis.

Involvement of IGF-1/IGFBP-3 signaling on the conspicuousness of facial pores

Conspicuous facial pores are one type of serious esthetic defects for many women. We previously reported that the severity of impairment of skin architecture around facial pores correlates well with the appearance of facial pores in several ethnic groups. In our last report, we showed that serum levels of insulin-like growth factor-1 (IGF-1) correlate well with facial pore size and with the severity of impairment of epidermal architecture around facial pores. However, our results could not fully explain the implication between facial pores and IGF signaling. In this study, we conducted a histological analysis of facial skin to determine whether potential changes in IGF-1 availability occur in the skin with or without conspicuous pores. Immunohistochemical observations showed that expression of insulin-like growth factor binding protein-3 (IGFBP-3) is limited to the suprapapillary epidermis around facial pores and to basal cells of rete pegs without tips in epidermis with conspicuous pores. In contrast, in basal cells of skin without conspicuous pores, IGFBP-3 expression is very low. Ki-67 and IGF-1 receptor-positive cells are abundant in basal cells in the tips of the rete pegs in skin with typical epidermal architecture around facial pores. No obvious differences were observed in the expression of filaggrin, involucrin, K1, K6 or K17 in skin with or without conspicuous pores. However, increased expression of K16 was observed in skin with conspicuous pores suggesting hyperproliferation. These results suggest that the IGF-1/IGFBP-3 signaling pathway is involved in the formation of conspicuous facial pores due to the epidermal architecture around facial pores.

Discovery of novel biomarkers in oral submucous fibrosis by microarray analysis

Oral submucous fibrosis (OSF) is a high-risk precancerous condition of the oral cavity. Areca nut chewing is its key etiologic factor, but the full pathogenesis is still obscure. In this study, microarray analysis was used to characterize the mRNA changes of 14,500 genes in four OSF and four normal buccal mucosa samples to identify novel biomarkers of OSF. Five candidate genes with the most differential changes were chosen for validation. The correlation between clinicopathologic variables of 66 OSF patients and the expression of each gene was assessed by immunohistochemistry. The microarray analysis showed that 661 genes were up-regulated (fold value >2) and 129 genes were down-regulated (fold value <0.5) in OSF (q < 0.01). The top three up-regulated genes [Loricrin, Cartilage oligomeric matrix protein (COMP), Cys-X-Cys ligand 9 (CXCL9)] with the largest fold changes and the top two down-regulated genes [keratin 19 (KRT19), cytochrome P450 3A5 (CYP 3A5)] with the most significantly differential changes in OSF were chosen as candidate biomarkers. In immunohistochemical results, the expression of Loricrin and COMP showed statistically significant association with histologic grade of OSF (P = 0.03 and 0.006, respectively). COMP was found to be overexpressed frequently in patients with the habit of areca nut chewing for more than 4 years (P = 0.002). CYP 3A5 was revealed an inverse correlation with histologic grade (P = 0.04). This pilot study showed that five novel genes might play important roles in the pathogenesis of OSF and may be clinically useful for early detection of OSF.

The upregulation of metallothionein-1 expression in areca quid chewing-associated oral squamous cell carcinomas

Metallothioneins (MTs) are a family of low molecular weight, cysteine-rich, inducible, intracellular proteins that bind heavy metals with high affinity. MT-1 is known as a stress-inducible protein and functions as an antioxidant enzyme. Areca quid chewing is a major risk factor in the development and further progression of oral squamous cell carcinoma (OSCC). The aim of this study was to compare MT-1 expression in normal human oral epithelium and OSCC and further explore the potential mechanism that may lead to induce MT-1 expression. Thirty four OSCC and 10 normal epithelium specimens were examined by immunohistochemistry and analyzed by the clinico-pathological profiles. The oral epithelial cell line GMN cells were challenged with arecoline, a major areca nut alkaloid, by reverse-transcriptase polymerase chain reaction. Furthermore, tobacco smoke carcinogen benzo[a]pyrene (BaP) and glutathione (GSH) precursor N-acetyl-l-cysteine (NAC) were added to find the possible regulatory mechanisms. The results from immunohistochemistry demonstrated that MT-1 expression was significantly higher in OSCC specimens (p<0.05). No significant difference in MT-1 expression was observed with respect to age, sex, T category, and stage (p>0.05). The high MT-1 expression was associated with lymph node metastasis (p=0.012). In addition, arecoline was found to elevate MT-1 mRNA in a dose-dependent manner (p<0.05). Furthermore, the addition of BaP enhanced the arecoline-induced MT-1 expression (p<0.05). The addition of NAC markedly inhibited the arecoline-induced MT-1 expression (p<0.05). These results lead to the conclusion that MT-1 expression is significantly upregulated in areca quid chewing associated-OSCC. The expression profile suggests MT-1 could be used clinically as a marker for tumors possessing the potential for lymph node metastasis. The compounds of tobacco products may act synergistically in the pathogenesis of OSCC in areca quid chewers. The regulation of MT-1 expression induced by arecoline is critically dependent on the intracellular GSH concentration.

The upregulation of heat shock protein 70 expression in areca quid chewing-associated oral squamous cell carcinomas

Heat shock protein 70 (HSP70) is an important stress-induced protein. Areca quid chewing is a major risk factor of oral squamous cell carcinoma (OSCC). The aim of this study was to compare HSP70 expression in normal human oral epithelium and OSCC and further to explore the potential mechanisms that may lead to induce HSP70 expression. 41 OSCC and 10 normal epithelium specimens were examined by immunohistochemistry and analyzed by the clinico-pathological profiles. The oral epithelial cell line GNM cells were challenged with arecoline, a major areca nut alkaloid, by using Western blot analysis. Furthermore, glutathione precursor N-acetyl-l-cysteine (NAC), AP-1 inhibitor curcumin, extracellular signal-regulated protein kinase inhibitor PD98059, and protein kinase C inhibitor staurosporine were added to find the possible regulatory mechanisms. The results from immunohistochemistry demonstrated that HSP70 expression was significantly higher in OSCC specimens (p<0.05). No significant difference in HSP70 expression was observed with respect to age, sex, T category, and stage (p>0.05). The low HSP70 expression was associated with lymph node metastasis (p=0.005). The high HSP70 expression was found in poor differentiated tumor groups (p=0.036). Arecoline was found to elevate HSP70 expression in a dose- and time-dependent manner (p<0.05). The addition of NAC, curcumin, PD98059, and staurosporine markedly inhibited the arecoline-induced HSP70 expression (p<0.05). Taken together, HSP70 expression is significantly upregulated in areca quid chewing-associated OSCC. HSP70 could be used clinically as a marker for tumors possessing the potential for differentiation as well as lymph node metastasis. In addition, arecoline-induced HSP70 expression was downregulated by NAC, curcumin, PD98059, and staurosporine.

The role of epithelial-mesenchymal transition in oral squamous cell carcinoma and oral submucous fibrosis

Epithelial-mesenchymal transition (EMT) is an indispensable mechanism during morphogenesis. Interest and research in EMT are currently at a high level due to its important role in cancer and fibrosis. Emerging evidence suggests that EMT is also a crucial event in oral squamous cell carcinoma (OSCC). Oral submucous fibrosis (OSF) is a chronic debilitating disease and a premalignant condition of the oral cavity. It is characterized by a generalized submucosal fibrosis. The pathogenesis of the disease is not well established. Epidemiological evidence strongly indicates an association between the betel quid (BQ) chewing habit and OSF. In a simplistic view, OSF represents a failed wound-healing process of the oral mucosa after chronic, sustained injury. This review highlights the signaling pathways involved in EMT, recent advances in the study of EMT in OSCC, and summarizes the evidence supporting a role for EMT in the pathogenesis of OSF.

The upregulation of cystatin C in oral submucous fibrosis

Cystatin C is a 13kDa non-glycosylated basic protein belonging to cystatin family. It is consistently and dramatically upregulated in a variety of fibrotic diseases. The aim of this study was to compare cystatin C expression in normal human buccal mucosa and oral submucous fibrosis (OSF) specimens and further explore the potential mechanism that may lead to induction of cystatin C expression. Twenty-five OSF specimens and six of normal buccal mucosa were examined by immunohistochemistry. The activity of cystatin C from fibroblasts cultured from OSF and normal buccal mucosa were evaluated by using reverse-transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay. Furthermore, the effect of arecoline, the major areca nut alkaloid, was explored. Cystatin C expression was significantly higher in OSF specimens (p<0.05) and expressed mainly by fibroblasts, endothelial cells, and inflammatory cells. OSF demonstrated significantly higher cystatin C expression than normal buccal mucosa fibroblasts both in mRNA and protein levels (p<0.05). In addition, arecoline was also found to elevate cystatin C mRNA and protein expression in a dose-dependent manner (p<0.05). Taken together, the data demonstrate that cystatin C expression is significantly upregulated in OSF from areca quid chewers and arecoline may be responsible for the enhanced cystatin C expression in vivo.