Activation of TGF-β pathway by areca nut constituents: a possible cause of oral submucous fibrosis

TUSC3, p53 and p21 genetic association with development of oral submucous fibrosis and oral squamous cell carcinoma among addictive tobacco chewers of Pakistan

BACKGROUND

This study delves into the intricate landscape of oral cancer, a global concern with a high incidence in Asian countries. We focus on oral squamous cell carcinoma (OSCC), primarily driven by the consumption of betel nut and its derivatives. OSCC often arises from premalignant lesions like oral submucous fibrosis (OSF). In Pakistan, OSCC is prevalent among men due to various addictive substances, including smokeless tobacco and chewing materials. Mutations in tumor suppressor genes, such as TP53 and p21, play crucial roles in this malignancy's development. We also explore the involvement of TUSC3 gene deletion in OSCC and OSF.

METHODS

In this study we investigated demographics, TUSC3 gene expression, deletion analysis, and TP53 and p21 genetic alterations in OSCC and OSF patients (blood and tissue of 50 samples in each condition) who had tobacco derivates usage history. The association analysis was carried out mainly through PCR based genotyping.

RESULTS

The study's patient cohort (OSCC and OSF) displayed a wide age range from 13 to 65 years (Mean = 32.96 years). Both conditions were more prevalent in males, with a male-female ratio of approximately 2.5:1. Chewing habits analysis revealed high frequencies of gutka use in both OSF and OSCC patients. TUSC3 expression analysis in OSCC cell lines indicated significant downregulation. Genotyping showed no TUSC3 deletion in OSF cases, but a deletion rate of over 22% in OSCC tissue samples. Analysis supported a significant association of TUSC3 deletion with OSCC development but not with OSF. Polymorphism in p53 exon 4 and p21 (rs1801270) were significantly associated with both OSCC and OSF, adding to their pathogenesis. Our findings further revealed a strong correlation between TUSC3 deletion and the excessive use of tobacco and related products, shedding light on the genetic underpinnings of OSCC development.

CONCLUSIONS

Notably, our study provides a crucial insight into genetic aspects underlying OSCC and OSF in response of addictive consumption of areca nut, betel quid, and tobacco derivatives. A significant association between TUSC3 deletion and OSCC development, along with polymorphisms in TP53 and p21, underscores the importance of further research into the molecular mechanisms driving oral cancer progression for improved diagnosis and treatment outcomes.

Plant leads for mitigation of oral submucous fibrosis: Current scenario and future prospect

The aim of this review is to enumerate medicinal plants and their bioactive compounds that may become potential leads in the mitigation of oral submucous fibrosis (OSMF) in the forthcoming future. It is focused on pathophysiology, risk factors, current treatment regimen, potential plant leads, and future therapies for OSMF. Data were extracted from a vast literature survey by using SciFinder, Web of Science, Google Scholar, and PubMed search engines with relevant keywords. Upon literature survey, we found that the phytochemical 'arecoline' present in the areca nut is the main causative agent of OSMF condition. Currently, OSMF is treated by immunomodulatory and anti-inflammatory agents such as corticosteroids, enzymes (hyaluronidase, chymotrypsin, and collagenase), anti-inflammatory mediators (isoxsuprine and pentoxifylline), dietary supplements (vitamins, antioxidants, and micronutrients), and anti-fibrotic cytokines like interferon-gamma that provides short-term symptomatic relief to OSMF patients. However, some plant leads have been proven effective in alleviating symptoms and mitigating OSMF, which ultimately improves the quality of OSMF patients' life. We concluded that plant drugs like lycopene, curcumin, Aloe vera, colchicine, and Glycyrrhiza glabra are effective against OSMF in various in vitro and/or clinical studies and are being used by modern and traditional practitioners.

Stromal thrombospondin 1 suppresses angiogenesis in oral submucous fibrosis

A decline in mucosal vascularity is a histological hallmark of oral submucous fibrosis (OSF), a premalignant disease that is largely induced by betel quid chewing. However, the lack of available models has challenged studies of angiogenesis in OSF. Here, we found that the expression of thrombospondin 1 (THBS1), an endogenous angiostatic protein, was elevated in the stroma of tissues with OSF. Using a fibroblast-attached organoid (FAO) model, the overexpression of THBS1 in OSF was stably recapitulated in vitro. In the FAO model, treatment with arecoline, a major pathogenic component in areca nuts, enhanced the secretion of transforming growth factor (TGF)-β1 by epithelial cells, which then promoted the expression of THBS1 in fibroblasts. Furthermore, human umbilical vein endothelial cells (HUVECs) were incorporated into the FAO to mimic the vascularized component. Overexpression of THBS1 in fibroblasts drastically suppressed the sprouting ability of endothelial cells in vascularized FAOs (vFAOs). Consistently, treatment with arecoline reduced the expression of CD31 in vFAOs, and this effect was attenuated when the endothelial cells were preincubated with neutralizing antibody of CD36, a receptor of THBS1. Finally, in an arecoline-induced rat OSF model, THBS1 inhibition alleviated collagen deposition and the decline in vascularity in vivo. Overall, we exploited an assembled organoid model to study OSF pathogenesis and provide a rationale for targeting THBS1.

Cyclic increase in the ADAMTS1-L1CAM-EGFR axis promotes the EMT and cervical lymph node metastasis of oral squamous cell carcinoma

The matrix metalloprotease A disintegrin and metalloprotease with thrombospondin motifs 1 (ADAMTS1) was reported to be involved in tumor progression in several cancer types, but its contributions appear discrepant. At present, the role of ADAMTS1 in oral squamous cell carcinoma (SCC; OSCC) remains unclear. Herein, The Cancer Genome Atlas (TCGA) database showed that ADAMTS1 transcripts were downregulated in head and neck SCC (HNSCC) tissues compared to normal tissues, but ADAMTS1 levels were correlated with poorer prognoses of HNSCC patients. In vitro, we observed that ADAMTS1 expression levels were correlated with the invasive abilities of four OSCC cell lines, HSC-3, SCC9, HSC-3M, and SAS. Knockdown of ADAMTS1 in OSCC cells led to a decrease and its overexpression led to an increase in cell-invasive abilities in vitro as well as tumor growth and lymph node (LN) metastasis in OSCC xenografts. Mechanistic investigations showed that the cyclic increase in ADAMTS1-L1 cell adhesion molecule (L1CAM) axis-mediated epidermal growth factor receptor (EGFR) activation led to exacerbation of the invasive abilities of OSCC cells via inducing epithelial-mesenchymal transition (EMT) progression. Clinical analyses revealed that ADAMTS1, L1CAM, and EGFR levels were all correlated with worse prognoses of HNSCC patients, and patients with ADAMTS1high/L1CAMhigh or EGFRhigh tumors had the shortest overall and disease-specific survival times. As to therapeutic aspects, we discovered that an edible plant-derived flavonoid, apigenin (API), drastically inhibited expression of the ADAMTS1-L1CAM-EGFR axis and reduced the ADAMTS1-triggered invasion and LN metastasis of OSCC cells in vitro and in vivo. Most importantly, API treatment significantly prolonged survival rates of xenograft mice with OSCC. In summary, ADAMTS1 may be a useful biomarker for predicting OSCC progression, and API potentially retarded OSCC progression by targeting the ADAMTS1-L1CAM-EGFR signaling pathway.

Serpin peptidase inhibitor, clade E, member 2 is associated with malignant progression and clinical prognosis in oral squamous cell carcinoma

Background/purpose

The serpin peptidase inhibitor, clade E, member 2 (SERPINE2), is upregulated in breast cancer, prostate cancer, and urothelial carcinoma; however, limited information exists regarding its expression in oral cancer. Therefore, this study aimed to analyze the association between SERPINE2 expression and oral squamous cell carcinoma (OSCC) outcomes.

Materials and methods

SERPINE2 mRNA and protein expression in patients with head and neck squamous cell carcinoma and OSCC were investigated using online databases and tissue-array analysis. Its relationship with clinicopathological characteristics, OSCC prognosis and its biological function in OSCC cells were explored.

Results

Analysis using online databases revealed higher SERPINE2 expression in tumor tissues and its role as a prognostic factor. High SERPINE2 protein levels were significantly correlated with adverse pathological parameters, including advanced clinical stage and tumor status (P < 0.001), lymph nodes (P = 0.014), and distant metastases (P = 0.013). High SERPINE2 expression was associated with worse overall survival (P < 0.001) and was identified as an independent prognostic factor for OSCC. In vitro studies revealed that SERPINE2 knockdown significantly reduced cell proliferation, migration, and invasion in OSCC cell lines.

Conclusion

This study suggests that SERPINE2 may serve as a prognostic biomarker and potential therapeutic target for oral cancer.

Molecular pathways of oral submucous fibrosis and its progression to malignancy

OBJECTIVE

The review aims to comprehend various factors engaged in the alteration of molecular events resulting in Oral submucous fibrosis (OSMF) and its malignant transformation.

DESIGN

Literature pertinent to pathways involved in OSMF were explored in databases such as PubMed, Scopus and Google Scholar. The relevant literature was reviewed and critically appraised in this narrative review.

RESULTS

Areca nut components influence myriad of cellular molecules such as cytokines, growth factors, myofibroblasts, non-coding RNAs and alter their expression. These aberrantly expressed molecules drive the progression of OSMF from localized inflammation to fibrosis of buccal mucosa. The oral tissue suffers from oxidative stress, hypoxia, autophagy, aberration of cell cycle and DNA damage. Apoptosis of epithelial layer results in its atrophy facilitating deeper penetration of areca nut elements. With the advance of disease, epithelial-mesenchymal transition eventuates and promotes dysplasia. The jeopardized expression of various cellular molecules, suppressed apoptosis, along with increased genetic alterations and neovascularization favors the malignant transformation.

CONCLUSION

OSMF is a progressive disorder with complex mechanism of pathogenesis initiated by inflammation of oral mucosa. Continuous habit of areca nut chewing and the resulting insult to the tissues prevents healing process and is destined to debilitating disease which affects the quality of life with a higher probability of progression to malignancy.

MiR-424/TGIF2-Mediated Pro-Fibrogenic Responses in Oral Submucous Fibrosis

Oral submucous fibrosis (OSF) has been recognized as a potentially malignant disorder and is characterized by inflammation and the deposition of collagen. Among various regulators of fibrogenesis, microRNAs (miR) have received great attention but the detailed mechanisms underlying the miR-mediated modulations remain largely unknown. Here, we showed that miR-424 was aberrantly overexpressed in OSF tissues, and then we assessed its functional role in the maintenance of myofibroblast characteristics. Our results demonstrated that the suppression of miR-424 markedly reduced various myofibroblast activities (such as collagen contractility and migration ability) and downregulated the expression of fibrosis markers. Moreover, we showed that miR-424 exerted this pro-fibrosis property via direct binding to TGIF2, an endogenous repressor of the TGF-β signaling. In addition, our findings indicated that overexpression of miR-424 activated the TGF-β/Smad pathway, leading to enhanced myofibroblast activities. Altogether, our data revealed how miR-424 contributed to myofibroblast transdifferentiation, and targeting the miR-424/TGIF2 axis may be a viable direction for achieving satisfactory results from OSF treatment.

α-Mangostin Inhibits the Activation of Myofibroblasts via Downregulation of Linc-ROR-Mediated TGFB1/Smad Signaling

Oral submucous fibrosis (OSF) is a premalignant disorder and persistent activation of myofibroblasts is implicated in this pathological progression. Increasing attention has been addressed towards non-coding RNA-regulated myofibroblasts activities and the effects of phytochemicals on non-coding RNA modulation are of great importance. In the present study, we examined the anti-fibrosis property of α-mangostin, a xanthone isolated from the pericarp of mangosteen. We found that α-mangostin exhibited inhibitory potency in myofibroblast activities and expression of fibrosis markers at the concentrations that caused neglectable damage to normal cells. Apart from the downregulation of TGF-β1/Smad2 signaling, we found that α-mangostin attenuated the expression of long non-coding RNA LincROR as well. Our results demonstrated that the effects of α-mangostin on myofibroblast activation were reverted when LincROR was overexpressed. Additionally, we showed the expression of LincROR in OSF specimens was elevated and silencing of LincROR successfully attenuated myofibroblast characteristics and TGF-β1/Smad2 activation. Taken together, these findings indicated that the anti-fibrosis effects of α-mangostin merit consideration and may be due to the attenuation of LincROR.

Is Epithelial-Mesenchymal Transition a New Roadway in the Pathogenesis of Oral Submucous Fibrosis: A Comprehensive Review

Epithelial-mesenchymal transition (EMT) collectively refers to a series of episodes that reshape polarized, intact epithelial cells into discrete motile cells that can conquer the extracellular matrix (ECM). It performs a pivotal role in embryonic development, wound healing, and tissue repair. Surprisingly, the exact mechanism can also lead to the onset of malignancy and organ fibrosis contributing to scar formation and loss of function. transforming growth factor signaling, WNT signaling, Notch signaling, Hedgehog signaling, and receptor tyrosine kinase signaling, as well as non-transcriptional changes in response to extracellular cues, such as growth factors and cytokines, hypoxia, and contact with the surrounding ECM, are responsible for the initiation of EMT.

Although the pathogenesis of oral submucous fibrosis (OSMF) is multifactorial, compelling evidence suggests that it results from collagen deregulation. EMT is one of the spotlight events in the pathogenesis of OSMF, with myofibroblasts and keratinocytes being the victim cells. EMT is an essential step in both physiological and pathological events. The importance of EMT in the malignant development of OSMF and the inflammatory reaction preceding fibrosis implies a new upcoming area of research.

This review aims to focus on the EMT events that function as a double-edged sword between wound healing and fibrosis and further discuss the mechanisms along with the molecular pathways that direct changes in gene expression essential for the same in the oral cavity. As OSMF involves a risk of malignant transformation, understanding the cellular and molecular events will open more avenues for therapeutic breakthroughs targeting EMT.

Fucoidan-Mediated Inhibition of Fibrotic Properties in Oral Submucous Fibrosis via the MEG3/miR-181a/Egr1 Axis

Oral submucous fibrosis (OSF) is a chronic fibrotic remodeling disease that can progress to oral cancer. However, efficient clinical diagnosis and treatment methods for OSF are still lacking. This study investigated the anti-fibrotic effect of fucoidan on oral fibrosis. To evaluate the fibrotic ability (myofibroblast activities), we performed wound-healing, Transwell migration, and collagen contraction assays by using patient-derived normal and fibrotic buccal submucous fibroblasts (BMFs and fBMFs, respectively). RNA-sequencing and dual-luciferase reporter and RNA immunoprecipitation chip assays were performed to identify the clinical significance and molecular mechanism of non-coding RNAs. Fucoidan suppressed the myofibroblast activities and inhibited the MEG3 in fBMFs. MEG3 was overexpressed in the OSF tissue and was positively associated with myofibroblast markers. Knockdown of MEG3 markedly inhibited myofibroblast activities, which were restored by inhibiting miR-181a and overexpressing Egr1. The results from luciferase reporter and RIP assays confirmed that MEG3 functioned as a competing endogenous RNA (ceRNA) and could directly target miR-181a, thereby preventing the miR-181a-mediated translational repression of Egr1. This study demonstrated that MEG3 exerts a profibrotic effect on OSF by targeting miR-181a/Egr1. Therefore, the administration of fucoidan may serve as a potential therapeutic strategy for OSF by targeting the overexpression of MEG3.

Leaving no stone unturned: Role of profibrotic genes in oral submucous fibrosis - A systematic review

Introduction

Understanding the molecular pathogenesis of an entity helps in devising the mode of progression as well as mode of therapy. Even with years of research to claim the understanding of the molecular pathogenesis of oral submucous fibrosis (OSMF) is limited. More deeper knowledge of the genes responsible for this will help in understanding and managing this disease better.

Materials and Methods

The articles published during a time period of 1990-2020 were chosen in accordance with the inclusion and exclusion criteria according to the PRISMA guidelines.

Results

From a total of 80 articles obtained from both electronic search of PUBMED, EMBASE, MEDLINE and Cochrane registry as well as the manual search only 21 articles were selected and analyzed.

Conclusion

Careful analysis of the samples revealed that transforming growth factor-beta may be a potential biomarker or a candidate for targeted therapy in OSMF.

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.

Long Non-Coding RNAs in Oral Submucous Fibrosis: Their Functional Mechanisms and Recent Research Progress

Many studies have shown that most genomes are transcribed into non-coding RNAs (ncRNAs), including microRNAs (miRs) and long non-coding RNAs (lncRNAs), which can affect different cell characteristics. LncRNAs are long heterologous RNAs that regulate gene expression and various signaling pathways during homeostasis and development. Studies have shown that a lncRNA is an important regulatory molecule that can be targeted to change the physiology and function of cells. Expression or dysfunction of lncRNAs is closely related to various genetic, autoimmune, and metabolic diseases. The importance of ncRNAs in oral submucosal fibrosis (OSF) has garnered much attention in recent years. However, most research has focused on miRs. The role of these molecules in OSF is incompletely understood. This review focuses on the emerging role and function of lncRNAs in OSF as novel regulators. Finally, the potential functional role of lncRNAs as biomarkers for OSF diagnosis is also described. LncRNAs are expected to become a new therapeutic target, but more research is needed to understand their biological functions more deeply.

Adipose-derived mesenchymal stem cell exosomes inhibit transforming growth factor-β1-induced collagen synthesis in oral mucosal fibroblasts

Oral submucosal fibrosis (OSF) is a potentially malignant oral disorder that requires the further development of advanced treatment strategies. TGF-β1 has been reported to be the main trigger for the increased collagen production and reduced activity of matrix degradation pathways in OSF. Exosomes are key mediators of paracrine signaling that have been proposed for direct use as therapeutic agents for tissue repair and regeneration. The present study aimed to investigate the effects of human adipose-derived mesenchymal stem cell (ADSC) exosomes (ADSC-Exos) on TGF-β1-treated oral fibroblasts in vitro and to unravel the potential underlying mechanism of action. Oral mucosal fibroblasts were obtained from the buccal tissues of patients without OSF during extraction of the third molar. ADSCs were obtained from three healthy female individuals during liposuction procedures. ADSC-Exos were isolated by ultracentrifugation and identified by electron microscopy, nanoparticle tracking and western blotting. Immunofluorescence and immunocytochemistry staining were performed to measure the expression levels of vimentin and α-smooth muscle actin in the fibroblasts. Reverse transcription-quantitative PCR and western blotting were used to determine the expression levels of mRNAs and proteins associated with collagen production. The p38 MAPK activator anisomycin was used to identify the underlying mechanisms of the effects of ADSC-Exos on TGF-β1-induced collagen synthesis in oral mucosal fibroblasts. The results of the present study revealed that ADSC-Exos exhibited a cup- or sphere-shaped morphology, with a mean diameter of 58.01±16.17 nm. ADSC-Exos were also found to be positive for CD63 and tumor susceptibility 101 expression. ADSC-Exos treatment reversed the TGF-β1-induced upregulation of collagen I and III protein expression. In addition, in the presence of TGF-β1, the expression levels of collagen type I α 1 chain and collagen type III α 1 chain mRNA were downregulated, whilst the expression levels of matrix metalloproteinase (MMP)1 and MMP3 were upregulated following ADSC-Exos treatment. The TGF-β1-induced upregulation in the phosphorylation of p38 in addition to the increased protein expression of collagens I and III were also reversed in fibroblasts following ADSC-Exos treatment. However, anisomycin treatment alleviated these ADSC-Exos-induced changes. In conclusion, findings from the present study suggest that ADSC-Exos may represent a promising strategy for OSF treatment by targeting the p38 MAPK signaling pathway.

Paeonol inhibits profibrotic signaling and HOTAIR expression in fibrotic buccal mucosal fibroblasts

BACKGROUND/PURPOSE

Betel nut chewing is the major risk factor of oral submucous fibrosis (OSF). Various studies have sought to discover alternative strategies to alleviate oral fibrogenesis. In the present study, we aimed to evaluate the anti-fibrosis effect of paeonol, a phenolic component derived from Paeonia Suffruticosa.

METHODS

The cytotoxicity of paeonol was tested using normal and fibrotic buccal mucosal fibroblasts (fBMFs) derived from OSF tissues. Collagen gel contraction, Transwell migration, invasion, and wound healing capacities were examined. Besides, the activation of TGF-β/Smad2 signaling and expression levels of type I collagen, α-SMA, and long non-coding RNA HOTAIR were measured as well.

RESULTS

Paeonol exerted a higher cytotoxic effect on fBMFs compared to normal BMFs. The arecoline-induced myofibroblast activities, including collagen gel contractility, cell motility, and wound healing ability were all suppressed by paeonol treatment. In addition, the activation of the TGF-β/Smad2 pathway was inhibited along with a lower expression of α-SMA and type I collagen in paeonol-treated cells. Also, the administration of paeonol decreased the mRNA expression of HOTAIR in fBMFs.

CONCLUSION

Our results indicate that paeonol may be a promising compound to attenuate the progression of oral fibrogenesis in OSF patients.

Understanding the molecular mechanism associated with reversal of oral submucous fibrosis targeting hydroxylysine aldehyde-derived collagen cross-links

Fibrosis is a pathological state characterized by excessive deposition of the extracellular matrix components leading to impaired tissue function in the affected organ. It results in scarring of the affected tissue akin to an over-healing wound as a consequence of chronic inflammation and repair in response to injury. Persistent trauma of susceptible oral mucosa due to habitual chewing of betel quid resulting in zealous healing of the mucosal tissue is one plausible explanation for the onset of oral submucous fibrosis (OSF). The irreversibility and resistance of collagen to degradation and its high potential to undergo malignant change are a major reason for morbidity in OSF. Hence, early diagnosis and timely treatment are crucial to prevent the progression of OSF to malignancy. This review focuses on the mechanistic insight into the role of collagen cross-links in advancing fibrosis and possible therapeutic targets that bring about a reversal of fibrosis. These options may be beneficial if attempted as a specific therapeutic modality in OSF as is in organ fibrosis. The upregulation of lysyl oxidase and lysyl hydroxylase has been shown to exhibit the higher levels of the hydroxylysine aldehyde-derived cross-links in fibrosis and tumor stroma promoting the tumor cell survival, resistance, and invasion. The in silico analysis highlights the potential drugs that may target the genes regulating collagen crosslinking.

The functional roles of microRNAs in the pathogenesis of oral submucous fibrosis

Oral potentially malignant disorders (OPMD) are lesions that may precede the onset of cancers in the oral cavity, and oral submucosal fibrosis (OSF) is one of the OPMD that is usually found in the buccal mucosa. Considerable effort has been made to elucidate the pathogenesis of OSF, and emerging evidence has suggested that microRNAs may play significant roles in the development of OSF. Several studies demonstrated that aberrant expression of miRNAs is also observed in the fibrotic BMFs (fBMFs) derived from OSF tissues. For instance, it has been shown that miR-10b, miR-21, and miR-1246 are significantly elevated, and miR-29b, miR-200b, and miR-200c are reduced in fBMFs. This review systematically summarizes the current knowledge regarding the aberrant expression of microRNAs, molecular mechanisms underlying oral fibrogenesis by the dysregulated microRNAs, and how the interaction between microRNAs and long non-coding RNAs contributes to the progression of OSF. An overview of the modes of action by these microRNAs will provide a fundamental basis for clinical application.

Depletion of miR-155 hinders the myofibroblast activities and reactive oxygen species generation in oral submucous fibrosis

BACKGROUND/PURPOSE

Emerging evidence suggests the significance of microRNA-155 (miR-155) in fibrogenesis and oxidative stress accumulation, but its function in oral submucous fibrosis (OSF) has not been investigated. In this study, we assessed the expression of miR-155 and its effects on the maintenance of myofibroblast activation.

METHODS

qRT-PCR was conducted to assess the expression of miR-155 in OSF tissues and fibrotic buccal mucosal fibroblasts (fBMFs) derived from OSF samples. Collagen gel contraction, migration, and invasion capabilities were examined in fBMFs. DCFDA ROS assay was used to examine ROS generation. A luciferase reporter assay was carried out to verify the relationship between miR-155 and its potential target RPTOR.

RESULTS

We showed that the expression of miR-155 was aberrantly upregulated in OSF specimens and fBMFs. Inhibition of miR-155 ameliorated various myofibroblast activities, including collagen gel contraction, migration, and invasion abilities as well as ROS production. Results from the luciferase reporter assay demonstrated that miR-155 directly interacted with its target RPTOR.

CONCLUSION

Taken together, these findings indicate that miR-155 is implicated in the pathogenesis of oxidative stress-associated OSF, possibly through the regulation of RPTOR.

Potential Application of an Aqueous Extract of Tinospora Cordifolia (Thunb.) Miers (Giloy) in Oral Submucous Fibrosis-An In Vitro Study

The in vitro antifibrotic activity of Tinospora cordifolia (Thunb.) Miers (giloy) was assessed to explore its potential for the management of oral submucous fibrosis. Epithelial cells dissociated from the tissue obtained from histopathologically normal oral mucosa during surgical extraction of third molars were cultured and fibrosis was induced by TGF-β1 in the oral keratinocytes. Cell viability was assessed by MTT and comparative gene expression analysis was carried out in the fibrosis-induced oral keratinocytes treated with various concentrations of Tinospora cordifolia extract (TcE) for matricellular protein-related gene expression. Concentrations of 0.5 µg/mL and 1 µg/mL TcE demonstrated a significant reduction in the expression of CTGF, SERPINE1, COL1A1, FN1, MMP1, MMP2, MMP3, and TIMP2 and an increase in the expression of PLAU, COL3A1, TIMP1, and TIMP3. Although TcE was found to reduce the expression of several fibrotic genes and increase the expression of antifibrotic genes, a varied effect was found, causing increased expression of COL3A1 and decreased expression of TIMP2 on TGF-β1-induced human buccal epithelial cells. However, further studies are warranted to assess the exact mechanism of antifibrotic activity and its clinical applications.

Honokiol inhibits arecoline-induced oral fibrogenesis through transforming growth factor-β/Smad2/3 signaling inhibition

BACKGROUND/PURPOSE

The habit of areca nut chewing has been regarded as an etiological factor of precancerous oral submucous fibrosis (OSF). In the present study, we aimed to evaluate the anti-fibrosis effect of honokiol, a polyphenolic component derived from Magnolia officinalis.

METHODS

The cytotoxicity of honokiol was tested using normal and fibrotic buccal mucosal fibroblasts (fBMFs) derived from OSF tissues. Collagen gel contraction, Transwell migration, invasion, and wound healing capacities were examined. Besides, the expression of TGF-β/Smad2 signaling as well as α-SMA and type I collagen were measured as well.

RESULTS

Honokiol exerted higher cytotoxicity of fBMFs compared to normal cells. The arecoline-induced myofibroblast activities, including collagen gel contractility, cell motility and wound healing capacities were all suppressed by honokiol treatment. In addition, the expression of the TGF-β/Smad2 pathway was downregulated along with a lower expression of α-SMA and type I collagen in honokiol-receiving cells.

CONCLUSION

Our data suggest that honokiol may be a promising compound to alleviate the progression of oral fibrogenesis and prevent the transformation of OSF oral epithelium into cancer.

Small Molecule "Silmitasertib" Repurposed as Inhibitor of Transforming Growth Factor Beta 1 for the Development of Therapeutics for Oral Submucous Fibrosis

Oral submucous fibrosis (OSMF) is considered a premalignant condition characterized by aggressive fibrosis of the submucosal tissues of the oral cavity reflecting its malignant transformation potential. Activation of transforming growth factor beta (TGF-β) signaling has been reported to lead increased collagen production and fibrosis. Recently, significant upregulation of TGF-β1 has been reported in OSMF as compared to normal tissues. Therefore, inhibition of the TGF-β1 may pave for the development of therapeutics of OSMF. Based on the structure-assisted drug designing, we found "silmitasertib" as potent inhibitor of TGF-β1. We suggest that this molecule can be validated and implemented for the treatment of OSMF.

Targeting lncRNA H19/miR-29b/COL1A1 Axis Impedes Myofibroblast Activities of Precancerous Oral Submucous Fibrosis

Oral submucous fibrosis (OSF) is known as a potentially malignant disorder, which may result from chemical irritation due to areca nuts (such as arecoline). Emerging evidence suggests that fibrogenesis and carcinogenesis are regulated by the interaction of long noncoding RNAs (lncRNAs) and microRNAs. Among these regulators, profibrotic lncRNA H19 has been found to be overexpressed in several fibrosis diseases. Here, we examined the expression of H19 in OSF specimens and its functional role in fibrotic buccal mucosal fibroblasts (fBMFs). Our results indicate that the aberrantly overexpressed H19 contributed to higher myofibroblast activities, such as collagen gel contractility and migration ability. We also demonstrated that H19 interacted with miR-29b, which suppressed the direct binding of miR-29b to the 3′-untranslated region of type I collagen (COL1A1). We showed that ectopic expression of miR-29b ameliorated various myofibroblast phenotypes and the expression of α-smooth muscle actin (α-SMA), COL1A1, and fibronectin (FN1) in fBMFs. In OSF tissues, we found that the expression of miR-29b was downregulated and there was a negative correlation between miR-29b and these fibrosis markers. Lastly, we demonstrate that arecoline stimulated the upregulation of H19 through the transforming growth factor (TGF)-β pathway. Altogether, this study suggests that increased TGF-β secretion following areca nut chewing may induce the upregulation of H19, which serves as a natural sponge for miR-29b and impedes its antifibrotic effects.

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.

The Role of Increased Connective Tissue Growth Factor in the Pathogenesis of Oral Submucous Fibrosis and its Malignant Transformation-An Immunohistochemical Study

Connective tissue growth factor (CTGF), a matricellular protein of the CCN family of extracellular matrix-associated heparin-binding proteins, is highly expressed in various organ fibrosis and several malignant tumors. Although a few studies have been conducted using CTGF in oral submucous fibrosis (OSF) and oral squamous cell carcinoma, no study has demonstrated its relation with various stages of OSF and its malignant transformation. The present study investigated the possible role of CTGF in the pathogenesis of OSF and its malignant transformation by using immunohistochemistry. Ten formalin-fixed paraffin-embedded tissue blocks, each of Stage 1 OSF, Stage 2 OSF, Stage 3 OSF, Stage 4 OSF, well- differentiated squamous cell carcinoma (WDSCC) with OSF and WDSCC without OSF were stained for CTGF by immunohistochemistry. Ten cases of healthy buccal mucosa (NOM) were included as controls. The present study demonstrated a statistically significant expression of CTGF in the epithelium and connective tissue of OSF and WDSCC with and without OSF cases against its complete absence in NOM. We observed an upregulation of CTGF expression from NOM to various stages of OSF to WDSCC with or without OSF. A gradual upregulation of the CTGF expression in various stages of OSF to WDSCC (with and without OSF) against its complete absence in NOM suggests that CTGF plays an important role in the pathogenesis of OSF and its malignant transformation.

Inhibition of lncRNA HOTTIP ameliorated myofibroblast activities and inflammatory cytokines in oral submucous fibrosis

BACKGROUND/PURPOSE

Long non-coding RNA HOXA transcript at the distal tip (HOTTIP) has been reported to contribute to multiple carcinomas, but whether it involves in the progression of precancerous conditions remains to be determined. Oral submucous fibrosis (OSF) has been known as an oral potentially malignant disorder and attributed to the persistent activation of the myofibroblast.

METHODS

The relative expression of HOTTIP in OSF tissues has been employed by RNA-sequencing and RT-PCR analysis. HOTTIP associated myofibroblasts activities and markers in fibrotic buccal mucosal fibroblast (fBMFs) through loss of function approaches have been evaluated.

RESULTS

In the present study, we found that the expression of HOTTIP was overexpressed in the OSF tissues and positively correlated with several fibrosis markers. To investigate its significance of myofibroblast activation, we first verified the expression level of HOTTIP in the patient-derived fibrotic buccal mucosal fibroblast (fBMFs) was upregulated and conducted the shRNA-mediated knockdown experiment to inhibit its expression followed by numerous examinations. We demonstrated that suppression of HOTTIP downregulated the expression of myofibroblast marker, α-SMA, and type I collagen along with the diminished myofibroblast activities (collagen gel contraction and migration capacities). Furthermore, we showed that silencing HOTTIP lessened the production of various pro-inflammatory cytokines (IL-6 and TNF-α).

CONCLUSION

Collectively, our results suggest that HOTTIP plays a crucial role in the persistent activation of myofibroblasts as well as the chronic inflammation and collagen deposition.

Toward Regulatory Effects of Curcumin on Transforming Growth Factor-Beta Across Different Diseases: A Review

Immune response, proliferation, migration and angiogenesis are juts a few of cellular events that are regulated by transforming growth factor-β (TGF-β) in cells. A number of studies have documented that TGF-β undergoes abnormal expression in different diseases, e.g., diabetes, cancer, fibrosis, asthma, arthritis, among others. This has led to great fascination into this signaling pathway and developing agents with modulatory impact on TGF-β. Curcumin, a natural-based compound, is obtained from rhizome and roots of turmeric plant. It has a number of pharmacological activities including antioxidant, anti-inflammatory, anti-tumor, anti-diabetes and so on. Noteworthy, it has been demonstrated that curcumin affects different molecular signaling pathways such as Wnt/β-catenin, Nrf2, AMPK, mitogen-activated protein kinase and so on. In the present review, we evaluate the potential of curcumin in regulation of TGF-β signaling pathway to corelate it with therapeutic impacts of curcumin. By modulation of TGF-β (both upregulation and down-regulation), curcumin ameliorates fibrosis, neurological disorders, liver disease, diabetes and asthma. Besides, curcumin targets TGF-β signaling pathway which is capable of suppressing proliferation of tumor cells and invading cancer cells.

Arecoline suppresses epithelial cell viability by upregulating tropomyosin-1 through the transforming growth factor-β/Smad pathway

CONTEXT

Oral submucous fibrosis (OSF) is a chronic and progressive disease. Arecoline, present in betel nuts, has been proposed as a vital aetiological factor. However, the underlying mechanism remains unclear.

OBJECTIVES

This research elucidates the expression of tropomyosin-1 (TPM1) and its regulation mechanism in HaCaT cells treated with arecoline.

MATERIALS AND METHODS

HaCaT cells were assigned into three groups: (1) Control; (2) Treated with arecoline (0.16 mM) for 48 h (3) Treated with arecoline (0.16 mM) and transfected with small interfering RNA (siRNA) for TPM1 (50 nM) for 48 h. CCK8, cell cycle, and apoptosis phenotypic analyses were performed. PCR and western blot analyses were performed to detect the expression level of TPM1 and examine the related signalling pathway.

RESULTS

The IC₅₀ of arecoline was approximately 50 μg/mL (0.21 mM). The arecoline dose (0.16 mM) and time (48 h) markedly increased TPM1 expression at the mRNA and protein levels in HaCaT cells. Arecoline suppressed the cell growth, caused cell cycle arrest at the G1 phase, and induced cell apoptosis in HaCaT cells. siRNA-mediated knockdown of TPM1 attenuated the effect of arecoline on cell proliferation, apoptosis, and cell cycle arrest at the G1 phase. Furthermore, blocking of the transforming growth factor (TGF)-β receptor using SB431542 significantly suppressed TPM1 expression in the cells treated with arecoline.

DISCUSSION AND CONCLUSIONS

Arecoline suppresses HaCaT cell viability by upregulating TPM1 through the TGF-β/Smad signalling pathway. This research provides a scientific basis for further study of arecoline and TPM1 in OSF and can be generalised to broader pharmacological studies. TPM1 may be a promising molecular target for treating OSF.

Arecoline enhances miR-21 to promote buccal mucosal fibroblasts activation

BACKGROUND/PURPOSE

Oral submucous fibrosis (OSF) is an irreversible fibrosis disease and a potentially malignant disorder in the oral cavity. Various studies have shown that miR-21 was implicated in the fibrogenesis and carcinogenesis, but its functional role in the development of OSF has not been investigated.

METHODS

The expression levels of miR-21 in arecoline-stimulated normal buccal mucosal fibroblasts (BMFs) and OSF specimens were determined by qRT-PCR. Exogenous administration of TGF-β and its inhibitor (SB431542) were utilized to examine the involvement of TGF-β signaling in miR-21 alteration. Collagen gel contraction, transwell migration, and invasion assays were used to assess the myofibroblast activities. The relationship between α-SMA and miR-21 was calculated using the Pearson correlation coefficient.

RESULTS

MiR-21 expression was induced in BMFs by arecoline treatment in a dose-dependent manner. Our results showed that this upregulation was mediated by TGF-β signaling. Subsequently, we demonstrated that the administration of the miR-21 inhibitor suppressed the arecoline-induced myofibroblast characteristics, including a higher collagen gel contractility and cell motility, in normal BMFs. Furthermore, inhibition of miR-21 was sufficient to attenuate the myofibroblast features in fibrotic BMFs. Besides, we showed that the expression of miR-21 was aberrantly upregulated in the OSF tissues and there was a positive correlation between miR-21 and myofibroblast marker, α-SMA.

CONCLUSION

MiR-21 overexpression in OSF may be due to the stimulation of areca nut, which was mediated by the TGF-β pathway. Our data suggested that the repression of miR-21 was a promising direction to palliate the development and progression of OSF.

Oxidative-protective effect of nuclear receptor coactivator 7 on arecoline-induced endothelial-to-mesenchymal transition

OBJECTIVE

Overproduction of reactive oxygen species (ROS) has been implicated in inflammatory activities and tumorigenesis in oral submucous fibrosis (OSF). Nuclear receptor coactivator 7 (NCOA7) is capable of regulating cellular responses to ROS. The aim of this study was to investigate the expression of NCOA7 in endothelial cells and the role of NCOA7 in areca nut-induced endothelial-to-mesenchymal transition (EndMT).

STUDY DESIGN

Immunohistochemistry and immunofluorescence were used to detect the expression of NCOA7 in endothelia. Human umbilical vein endothelial cells (HUVECs) were treated with various dosages of arecoline (0, 5, 10, 20 μg/mL); then NCOA7 expression, the correlation of NCOA7 with EndMT, and the potential signaling were analyzed by using small interfering RNA (siRNA) transfection, reverse transcription polymerase chain reaction, Western blotting, and flow cytometry.

RESULTS

NCOA7 was significantly elevated in OSF tissues, as detected with immunohistochemistry and immunofluorescence. After arecoline treatment, NCOA7 expression and EndMT were induced in HUVECs. Transfection of HUVECs with si-NCOA7, which reduced 73% of NCOA7 expression, aggravated the arecoline-induced EndMT process. Inhibition of ROS markedly, but not completely, reverses this arecoline-induced EndMT in si-NCOA7 cells.

CONCLUSIONS

This study highlights NCOA7 as a potential target for therapeutic intervention to mediate EndMT via ROS species production.

Genetic Susceptibility and Protein Expression of Extracellular Matrix Turnover-Related Genes in Oral Submucous Fibrosis

Betel quid (BQ) chewing increased the risk of oral cancer and oral submucous fibrosis (OSMF), an oral premalignant disorder (OPMD) with malignant transformation potential. BQ components such as areca nut (AN), trauma by coarse AN fiber, catechin, copper, alkaloids, stimulated reactive oxygen species (ROS), inflammation and cytotoxicity are suggested to be the contributing factors. They may induce tissue inflammation, proliferation of fibroblasts and collagen deposition, myofibroblast differentiation and contraction, collagen cross-links and inhibit collagen phagocytosis, finally leading to the development of OSMF and oral cancer. These events are mediated by BQ components-induced changes of extracellular matrix (ECM) turnover via regulation of TGF-β1, plasminogen activator inhibitor-1 (PAI-1), cystatin, lysyl oxidase (LOX) and tissue inhibitors of metalloproteinases (TIMPs) and metalloproteinases (MMPs). Genetic susceptibility is also involved in these disease processes. Further understanding the molecular mechanisms of BQ-induced OSMF and oral cancer can be helpful for future disease prevention and treatment.

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.

Index of Cancer-Associated Fibroblasts Is Superior to the Epithelial-Mesenchymal Transition Score in Prognosis Prediction

In many solid tumors, tissue of the mesenchymal subtype is frequently associated with epithelial–mesenchymal transition (EMT), strong stromal infiltration, and poor prognosis. Emerging evidence from tumor ecosystem studies has revealed that the two main components of tumor stroma, namely, infiltrated immune cells and cancer-associated fibroblasts (CAFs), also express certain typical EMT genes and are not distinguishable from intrinsic tumor EMT, where bulk tissue is concerned. Transcriptomic analysis of xenograft tissues provides a unique advantage in dissecting genes of tumor (human) or stroma (murine) origins. By transcriptomic analysis of xenograft tissues, we found that oral squamous cell carcinoma (OSCC) tumor cells with a high EMT score, the computed mesenchymal likelihood based on the expression signature of canonical EMT markers, are associated with elevated stromal contents featured with fibronectin 1 (Fn1) and transforming growth factor-β (Tgfβ) axis gene expression. In conjugation with meta-analysis of these genes in clinical OSCC datasets, we further extracted a four-gene index, comprising FN1, TGFB2, TGFBR2, and TGFBI, as an indicator of CAF abundance. The CAF index is more powerful than the EMT score in predicting survival outcomes, not only for oral cancer but also for the cancer genome atlas (TCGA) pan-cancer cohort comprising 9356 patients from 32 cancer subtypes. Collectively, our results suggest that a further distinction and integration of the EMT score with the CAF index will enhance prognosis prediction, thus paving the way for curative medicine in clinical oncology.

Positive Feedback Loop of SNAIL-IL-6 Mediates Myofibroblastic Differentiation Activity in Precancerous Oral Submucous Fibrosis

Oral submucosal fibrosis (OSF) is a premalignant disorder of the oral cavity, and areca nut chewing is known to be a major etiological factor that could induce epithelial to mesenchymal transition (EMT) and activate buccal mucosal fibroblasts (BMFs). However, this detailed mechanism is not fully understood. In this study, we showed that the upregulation of Snail in OSF samples and fibrotic BMFs (fBMFs) may result from constant irritation by arecoline, a major alkaloid of the areca nut. The elevation of Snail triggered myofibroblast transdifferentiation and was crucial to the persistent activation of fBMFs. Meanwhile, Snail increased the expression of numerous fibrosis factors (e.g., α-SMA and collagen I) as well as IL-6. Results from bioinformatics software and a luciferase-based reporter assay revealed that IL-6 was a direct target of Snail. Moreover, IL-6 in BMFs was found to further increase the expression of Snail and mediate Snail-induced myofibroblast activation. These findings suggested that there was a positive loop between Snail and IL-6 to regulate the areca nut-associated myofibroblast transdifferentiation, which implied that the blockage of Snail may serve as a favorable therapeutic strategy for OSF treatment.

Localized peripheral autonomous neuropathy and dysfunctional myoepithelial cells: A novel hypothesis for xerostomia in oral submucous fibrosis

Oral submucous fibrosis (OSMF) is a potentially malignant disorder of the oral cavity characterized by submucosal deposition of dense collagen bundles leading to limited mouth opening. Besides, patients also complain about the burning sensation in the oral cavity and xerostomia. These symptoms have a major impact on the functional and psychological domains of oral health-related quality of life. However, the pathogenesis of xerostomia in OSMF is not yet well established. In our routine histopathology practice, we observed fibrosis surrounding minor salivary glands, distended acini, obliteration of acinar lumen and loss of interstitial spaces. Based on these features, we hypothesized that fibrosis in OSMF drives localized peripheral autonomous neuropathy in minor salivary glands, which leads to dysfunctional myoepithelial cells. These dysfunctional myoepithelial cells will unable to contract and expel saliva out of the salivary secretary unit, thus leading to xerostomia. In the present paper, experiments are recommended to prove this hypothesis, which can be exploited in the future for the development of appropriate drugs.

Photobiomodulation therapy inhibits oral submucous fibrosis in mice

Objectives

Oral submucous fibrosis (OSMF) is a chronic inflammatory disease and a potentially malignant oral disorder. However, the best therapeutic treatment for OSMF remains uncertain. Our previous study showed that photobiomodulation (PBM) therapy and forskolin could reduce arecoline‐induced fibrosis reactions via the cAMP pathway. The present study aimed to establish an animal model of areca nut extract (ANE)‐induced OSMF and to evaluate the therapeutic potential of PBM and forskolin for ANE‐induced OSMF.

Subjects and methods

The mice were divided into five groups. The buccal tissues were harvested for histomorphological analysis and immunoblotting.

Results

Our results showed that PBM significantly reduced the development of ANE‐induced OSMF, quantified by changes in submucosal layer thickness and collagen deposition. Additionally, PBM could extensively reduce the protein expression of the fibrotic marker genes alpha‐smooth muscle actin (α‐SMA) and connective tissue growth factor (CTGF) in buccal submucous lesions. However, forskolin treatment significantly decreased the protein expression of fibrotic marker genes but slightly decreased the observed histomorphological changes.

Conclusions

We established an ANE‐induced OSMF mouse model, which also provided a model for the development of a therapeutic treatment for OSMF. The anti‐fibrotic effects of PBM and forskolin may be useful for clinical interventions.

Expression of transforming growth factor beta in oral submucous fibrosis

Background

Oral submucous fibrosis (OSMF) is a premalignant condition mainly caused by areca nut chewing and is characterized by progressive fibrosis of submucosal tissues and epithelial atrophy. Activation of transforming growth factor beta (TGF-β) signaling is considered main causative event for increased collagen production and fibrosis. In this study, molecular pathogenesis of OSMF was investigated based on the expression of the TGF-β genes in OSMF tissues compared to normal controls.

Methods

A total of 33 OSMF and 10 normal tissues were collected from patients and their clinic-epidemiological data was recorded. The expression of TGF-β isoform genes- TGF β1, TGF β2, TGF β3 and its receptor TGF βR1, TGF βR2 was studied by real time polymerase chain reaction (PCR). Comparison of the expression of these genes among normal controls and OSMF patients was done. The PCR results were confirmed by histopathological and immunohistochemical staining.

Results

The histological changes included atrophic epithelium, loss of rete ridges, presence of inflammatory cells and dense collagen bundles in connective tissue. PCR showed statistically significant upregulation of TGF-β isoforms in OSMF as compared to normal tissues. Of the three isoforms, maximum fold change was observed in TGF-β1. Similarly, both TGF-βR1 and TGF-βR2 were found to be elevated in OSMF tissues compared to normal. The semi-quantitative analysis by immunohistochemical staining revealed statistically significant difference between normal and OSMF tissues.

Conclusion

TGF-β signaling plays a major role in the molecular pathogenesis of OSMF as shown by increased mRNA expression of all the three TGF-β isotypes and their receptors.

Network-based identification of signature genes KLF6 and SPOCK1 associated with oral submucous fibrosis

The molecular mechanism of oral submucous fibrosis (OSF) is yet to be fully elucidated. The identification of reliable signature genes to screen patients with a high risk of OSF and to provide oral cancer surveillance is therefore required. The present study produced a filtering criterion based on network characteristics and principal component analysis, and identified the genes that were involved in OSF prognosis. Two gene expression datasets were analyzed using meta-analysis, the results of which revealed 1,176 biologically significant genes. A co-expression network was subsequently constructed and weighted gene modules were detected. The pathway and functional enrichment analyses of the present study allowed for the identification of modules 1 and 2, and their respective genes, SPARC (osteonectin), cwcv and kazal like domain proteoglycan 1 (SPOCK1) and kruppel like factor 6 (KLF6), which were involved in the occurrence of OSF. The results revealed that both genes had a prominent role in epithelial to mesenchymal transition during OSF progression. The genes identified in the present study require further exploration and validation within clinical settings to determine their roles in OSF.

Discoidin Domain Receptor-1 (DDR1) is Involved in Angiolymphatic Invasion in Oral Cancer

The discoidin domain receptor-1 (DDR1) is a non-integrin collagen receptor recently implicated in the collective cell migration of other cancer types. Previously, we identified an elevated expression of DDR1 in oral squamous cell carcinoma (OSCC) cells. Through the data mining of a microarray dataset composed of matched tumor-normal tissues from forty OSCC patients, we distilled overexpressed genes statistically associated with angiolymphatic invasion, including DDR1, COL4A5, COL4A6 and PDPN. Dual immunohistochemical staining further confirmed the spatial locations of DDR1 and PDPN in OSCC tissues indicative of collective cancer cell invasion. An elevated DDR1 expression at both the transcription and protein level was observed by treating keratinocytes with collagen of fibrillar or basement membrane types. In addition, inhibition of DDR1 kinase activity in OSCC TW2.6 cells disrupted cell cohesiveness in a 2D culture, reduced spheroid invasion in a collagen gel matrix, and suppressed angiolymphatic invasion in xenograft tissues. Taken together, these results suggest that collagen deposition in the affected tissues followed by DDR1 overexpression could be central to OSCC tumor growth and angiolymphatic invasion. Thus, DDR1 inhibitors are potential therapeutic compounds in restraining oral cancer, which has not been previously explored.

Comparative Evaluation of SMAD-2 Expression in Oral Submucous Fibrosis and Reactive Oral Lesions

BACKGROUND

The event of fibrosis encompasses involvement of definite immunological and molecular mechanisms. As quite a lot of pro-fibrotic pathways are concerned, a multipronged approach is obligatory to cognize the fibrotic events. SMAD signaling pathway hasn't been studied oral fibrotic events.In the progression of cramming the SMAD signaling pathway in OSMF, the first initiator protein of the pathway was considered for evaluation in the present study.

MATERIALS AND METHODS

A total of 100 subjects consisting of 20 controls, 40 patients with reactive lesions such as Traumatic Fibroma, Epulis Fissuratum and Gingival Hyperplasia and 40 patients with Oral Submucous Fibrosis were recruited for the study. Tissue homogenates were assayed by quantitative sandwich enzyme immunoassay technique using Human Mothers Against Decapentaplegic Homolog 2 (Smad2).

RESULTS

SMAD 2 expression values showed significant difference between control and OSMF group. However, the difference between reactive lesions with control and OSMF were not statistically significant.

CONCLUSION

Graded increase of SMAD 2 expression from control,reactive lesions and OSMF were observed accentuating the role of SMAD signalling pathway in fibro genesis. Further this can be validated to generate effective antifibrotic targets.

DNA hypermethylation of sirtuin 1 (SIRT1) caused by betel quid chewing-a possible predictive biomarker for malignant transformation

BACKGROUND

DNA hypermethylation of tumor suppressor genes is observed in precancerous lesions and oral cancer of individuals with the habits of betel quid (BQ) chewing. SIRT1 has been identified as playing a role in the maintenance of epithelial integrity, and its alteration is often related to carcinogenesis. However, the methylation and transcription status of SIRT1 in patients with BQ chewing-related oral cancer has not been investigated. We examined the methylation status of SIRT1 in paraffin-embedded tissue samples of oral squamous cell carcinoma (OSCC) obtained from BQ chewing and non-chewing patients and in tissue samples from healthy control subjects. In addition, we examined whether the hypermethylation of SIRT1 followed by its transcriptional downregulation in the human gingival epithelial cells could be caused by arecoline, a major component of BQ. Furthermore, we investigated the methylation status of SIRT1 in smear samples of macroscopically healthy buccal mucosa from subjects with a habit of BQ chewing.

RESULTS

SIRT1 was significantly hypermethylated in tissue samples of OSCC from BQ chewers and non-chewers than in oral mucosa from healthy control subjects. Results also showed that the hypermethylation level of SIRT1 was significantly higher in OSCC of patients with BQ chewing habits than in those of non-chewing habits (p < 0.05). Our in vitro model showed that hypermethylation is followed by downregulation of the transcriptional level of SIRT1 (p < 0.05). The methylation levels of SIRT1 in the smear samples obtained from BQ chewing individuals were significantly higher than those in the samples obtained from individuals that did not chew BQ. The duration of BQ chewing habits was correlated positively to the frequency of SIRT1 hypermethylation (p < 0.05).

CONCLUSIONS

Our results suggest that DNA hypermethylation of SIRT1 is involved in the occurrence of oral cancer in BQ chewing patients and that hypermethylation in the oral mucosa of BQ chewers could be a predictive marker for the occurrence of malignant transformation. This is the first report that showed DNA hypermethylation in clinically healthy oral epithelium of BQ chewers. Our study shows evidence that DNA hypermethylation may be an early event of oral carcinogenesis prior to observable clinical changes.

Molecular pathways regulated by areca nut in the etiopathogenesis of oral submucous fibrosis

Many oral mucosal lesions are due to substance abuse, such as tobacco and areca nut, amongst others. There is considerable evidence that oral lesions/disorders such as some leukoplakias, most erythroplakias, and submucous fibrosis have malignant potential, with a conversion rate of 5%-10% over a 10-year period. There have been several reports on possible biomarkers that predict malignant conversion of the oral lesions associated with these disorders. Management of these is mostly surgical removal of the lesion followed by observation, and in some cases treatment by antioxidants and anti-inflammatory agents. Oral submucous fibrosis is due to excessive deposition of extracellular matrix in the connective tissue plus, particularly, collagens. The deposition of collagen leads to stiffness of the affected regions and results in difficulty in mouth opening. Areca nut chewing is proposed as the most probable etiological factor in the manifestation of oral submucous fibrosis. Several studies suggest involvement of proinflammatory cytokines, dysregulated by areca nut, in the development of the disease. Amongst these, transforming growth factor-β is in the forefront, which is also shown to be involved in fibrosis of other organs. This review addresses the molecular mechanisms involved in oral submucous fibrosis development and provides a model for the regulation of transforming growth factor-β by areca nut. It provides an exemplar of the role of modern molecular techniques in the study of oral disease.

E3 ligase carboxyl-terminus of Hsp70-interacting protein (CHIP) suppresses fibrotic properties in oral mucosa

BACKGROUND/PURPOSE

Oral submucous fibrosis (OSF) represents a precancerous lesion of oral mucosa that may progress into oral cancer and its major etiological factor is areca nut chewing. Carboxyl-terminus of Hsp70-interacting protein (CHIP) functions as an ubiquitin E3 ligase and is associated with fibrosis diseases. In the current study, we sought to investigate whether CHIP participated in the areca nut-mediated OSF development.

METHODS

The mRNA expression of CHIP in arecoline-stimulated buccal mucosal fibroblasts (BMFs) and OSF tissues was determined by qRT-PCR. Collagen gel contraction, migration and invasion assays were carried out to evaluate the myofibroblast activation. The protein expression levels of α-SMA and transglutaminase 2 (TGM2) were assessed by Western blot.

RESULTS

The expression level of CHIP was reduced in BMFs following arecoline treatment in a dose-dependent manner, which was consistent with the observation of lower CHIP expression in OSF specimen compared to the normal counterparts. Ectopic expression of CHIP mitigated the myofibroblast activities, including elevated collagen gel contractility and cell motility. In addition, we showed that overexpression of CHIP downregulated the α-SMA and TGM-2 expression, which may lead to less fibrosis alteration.

CONCLUSION

CHIP may not only function as a key regulator of protein quality control but also a critical deciding factor to oral fibrogenesis. Our findings suggested that CHIP possesses the anti-fibrotic effect, which may be mediated by TGM2 regulation. Restoration of CHIP could be a therapeutic direction to help OSF patients.

Overview of biological mechanisms of human carcinogens

This review summarizes the carcinogenic mechanisms for 109 Group 1 human carcinogens identified as causes of human cancer through Volume 106 of the IARC Monographs. The International Agency for Research on Cancer (IARC) evaluates human, experimental and mechanistic evidence on agents suspected of inducing cancer in humans, using a well-established weight of evidence approach. The monographs provide detailed mechanistic information about all carcinogens. Carcinogens with closely similar mechanisms of action (e.g. agents emitting alpha particles) were combined into groups for the review. A narrative synopsis of the mechanistic profiles for the 86 carcinogens or carcinogen groups is presented, based primarily on information in the IARC monographs, supplemented with a non-systematic review. Most carcinogens included a genotoxic mechanism.

A prospective trial of CONfocal endomicroscopy in CYSTic lesions of the pancreas: CONCYST-01

Background and study aims  Pancreatic cystic lesions (PCL) are common. While some harbor malignant potential, accurate preoperative diagnosis remains challenging. Needle-based confocal laser endomicroscopy (nCLE) via a 19G FNA needle enables real-time imaging of the cyst wall. This study evaluated the safety and utility of nCLE in patients with an indeterminate PCL undergoing EUS-FNA. Patients and methods  The CONCYST study prospectively recruited patients with indeterminate PCL attending three hepatopancreaticobiliary (HPB) referral centers in the UK, with indeterminate PCL, who required EUS-FNA between July 2014 and October 2016. Following the procedure, all patients were followed up in telephone clinic for at least 12 months. Ethical approval for the study was granted by the National Research Ethics Service (14/LO/0040). Results  Sixty-seven patient were recruited, 11 excluded and 56 included in the final analysis: 35 male, 21 female; median age 68 (range 28 - 80). Recognizable confocal images were obtained in 48 of 56 cases. Median nCLE scanning time was 5 minutes and did not exceed 10 minutes in any case. EUS-nCLE findings correlated with final diagnosis (based on imaging, cytology and multidisciplinary team review) in 43/56 (77 %) of cases, compared with 37/56 (66 %) for cytology alone ( P  = 0.12). One patient experienced mild pruritus following the procedure and another developed an infected pseudocyst, which resolved with antibiotics. Conclusions  EUS-nCLE under conscious sedation in the day case setting is safe and provides additional information to standard EUS-FNA for diagnosing indeterminate PCL.