Slug mediates myofibroblastic differentiation to promote fibrogenesis in buccal mucosa

Targeting MetaLnc9/miR-143/FSCN1 axis inhibits oxidative stress and myofibroblast transdifferentiation in oral submucous fibrosis

Background/purpose

Persistent activation of myofibroblasts is attributed to various dysregulated biological events conferring multiple types of fibrosis diseases, including oral submucous fibrosis (OSF). Although the significance of non-coding RNAs (ncRNAs) in the occurrence of fibrosis has been appreciated, the detailed mechanisms still have not been fully elucidated. The aim of this study was to identify key dysregulated ncRNAs and elucidate their pro-fibrotic mechanisms in promoting myofibroblast activation and the pathological development of OSF.

Materials and methods

Expression of non-coding RNAs and mRNAs in OSF cohort was determined using RNA sequencing and qRT-PCR. The molecular axis of pro-fibrotic ncRNAs were exploited via luciferase reporter activity assay and RNA expression rescue experiments. Functional assays, including collagen gel contraction, wound healing ability, cell migration, and reactive oxygen species (ROS) production, were conducted to assess the changes in the myofibroblastic phenotypes of primary human buccal mucosal fibroblasts.

Results

Herein, we found that long non-coding RNA MetaLnc9 was upregulated in OSF specimens and positively associated with several fibrosis markers. Silencing of MetaLnc9 diminished the features of activated myofibroblasts and the production of ROS. We not only showed that MetaLnc9 functioned as a competitive endogenous RNA of microRNA (miR)-143, but also demonstrated that the pro-fibrosis effect of MetaLnc9 on myofibroblast activities was mediated by suppression of miR-143. Moreover, our data showed that fascin actin-bundling protein 1 (FSCN1) was a direct target of miR-143 and positively related to MetaLnc9.

Conclusion

Upregulation of MetaLnc9 may enhance the activation of myofibroblasts by sponging miR-143 and titrating its inhibitory property on FSCN1.

Exosomal miR-17-5p derived from epithelial cells is involved in aberrant epithelium-fibroblast crosstalk and induces the development of oral submucosal fibrosis

Oral submucous fibrosis (OSF) is a chronic and inflammatory mucosal disease caused by betel quid chewing, which belongs to oral potentially malignant disorders. Abnormal fibroblast differentiation leading to disordered collagen metabolism is the core process underlying OSF development. The epithelium, which is the first line of defense against the external environment, can convert external signals into pathological signals and participate in the remodeling of the fibrotic microenvironment. However, the specific mechanisms by which the epithelium drives fibroblast differentiation remain unclear. In this study, we found that Arecoline-exposed epithelium communicated with the fibrotic microenvironment by secreting exosomes. MiR-17-5p was encapsulated in epithelial cell-derived exosomes and absorbed by fibroblasts, where it promoted cell secretion, contraction, migration and fibrogenic marker (α-SMA and collagen type I) expression. The underlying molecular mechanism involved miR-17-5p targeting Smad7 and suppressing the degradation of TGF-β receptor 1 (TGFBR1) through the E3 ubiquitination ligase WWP1, thus facilitating downstream TGF-β pathway signaling. Treatment of fibroblasts with an inhibitor of miR-17-5p reversed the contraction and migration phenotypes induced by epithelial-derived exosomes. Exosomal miR-17-5p was confirmed to function as a key regulator of the phenotypic transformation of fibroblasts. In conclusion, we demonstrated that Arecoline triggers aberrant epithelium-fibroblast crosstalk and identified that epithelial cell-derived miR-17-5p mediates fibroblast differentiation through the classical TGF-β fibrotic pathway, which provided a new perspective and strategy for the diagnosis and treatment of OSF.

The deubiquitinase USP7 and E3 ligase TRIM21 regulate vasculogenic mimicry and malignant progression of RMS by balancing SNAI2 homeostasis

BACKGROUND

Rhabdomyosarcoma (RMS) is a rare malignancy and the most common soft tissue sarcoma in children. Vasculogenic mimicry (VM) is a novel tumor microcirculation model different from traditional tumor angiogenesis, which does not rely on endothelial cells to provide sufficient blood supply for tumor growth. In recent years, VM has been confirmed to be closely associated with tumor progression. However, the ability of RMS to form VM has not yet been reported.

METHODS

Immunohistochemistry, RT-qPCR and western blot were used to test the expression level of SNAI2 and its clinical significance. The biological function in regulating vasculogenic mimicry and malignant progression of SNAI2 was examined both in vitro and in vivo. Mass spectrometry, co-immunohistochemistry, immunofluorescence staining, and ubiquitin assays were performed to explore the regulatory mechanism of SNAI2.

RESULTS

Our study indicated that SNAI2 was abnormally expressed in patients with RMS and RMS cell lines and promoted the proliferation and metastasis of RMS. Through cell tubule formation experiments, nude mice Matrigel plug experiments, and immunohistochemistry (IHC), we confirmed that RMS can form VM and that SNAI2 promotes the formation of VM. Due to SNAI2 is a transcription factor that is not easily drugged, we used Co-IP combined with mass spectrometry to screen for the SNAI2-binding protein USP7 and TRIM21. USP7 depletion inhibited RMS VM formation, proliferation and metastasis by promoting SNAI2 degradation. We further demonstrated that TRIM21 is expressed at low levels in human RMS tissues and inhibits VM in RMS cells. TRIM21 promotes SNAI2 protein degradation through ubiquitination in the RMS. The deubiquitinase USP7 and E3 ligase TRIM21 function in an antagonistic rather than competitive mode and play a key role in controlling the stability of SNAI2 to determine the VM formation and progression of RMS.

CONCLUSION

Our findings reveal a previously unknown mechanism by which USP7 and TRIM21 balance the level of SNAI2 ubiquitination, determining RMS vasculogenic mimicry, proliferation, and migration. This new mechanism may provide new targeted therapies to inhibit the development of RMS by restoring TRIM21 expression or inhibiting USP7 expression in RMS patients with high SNAI2 protein levels.

A Critical Interpretive Synthesis of the Role of Arecoline in Oral Carcinogenesis: Is the Local Cholinergic Axis a Missing Link in Disease Pathophysiology?

Arecoline is the primary active carcinogen found in areca nut and has been implicated in the pathogenesis of oral squamous cell carcinoma (OSCC) and oral submucous fibrosis (OSF). For this study, we conducted a stepwise review process by combining iterative scoping reviews with a post hoc search, with the aim of identifying the specific mechanisms by which arecoline initiates and promotes oral carcinogenesis. Our initial search allowed us to define the current trends and patterns in the pathophysiology of arecoline-induced OSF and OSCC, which include the induction of cell proliferation, facilitation of invasion, adhesion, and migration, increased collagen deposition and fibrosis, imbalance in immune and inflammatory mechanisms, and genotoxicity. Key molecular pathways comprise the activation of NOTCH1, MYC, PRDX2, WNT, CYR61, EGFR/Pl3K, DDR1 signaling, and cytokine upregulation. Despite providing a comprehensive overview of potential pathogenic mechanisms of OSF, the involvement of molecules functioning as areca alkaloid receptors, namely, the muscarinic and nicotinic acetylcholine receptors (AChRs), was not elucidated with this approach. Accordingly, our search strategy was refined to reflect these evidence gaps. The results of the second round of reviews with the post hoc search highlighted that arecoline binds preferentially to muscarinic AChRs, which have been implicated in cancer. Consistently, AChRs activate the signaling pathways that partially overlap with those described in the context of arecoline-induced carcinogenesis. In summary, we used a theory-driven interpretive review methodology to inform, extend, and supplement the conventional systematic literature assessment workflow. On the one hand, the results of this critical interpretive synthesis highlighted the prevailing trends and enabled the consolidation of data pertaining to the molecular mechanisms involved in arecoline-induced carcinogenesis, and, on the other, brought up knowledge gaps related to the role of the local cholinergic axis in oral carcinogenesis, thus suggesting areas for further investigation.

Mare stromal endometrial cells differentially modulate inflammation depending on oestrus cycle status: an in vitro study

The modulation of inflammation is pivotal for uterine homeostasis. Here we evaluated the effect of the oestrus cycle on the expression of pro-inflammatory and anti-inflammatory markers in a cellular model of induced fibrosis. Mare endometrial stromal cells isolated from follicular or mid-luteal phase were primed with 10 ng/mL of TGFβ alone or in combination with either IL1β, IL6, or TNFα (10 ng/mL each) or all together for 24 h. Control cells were not primed. Messenger and miRNA expression were analyzed using real-time quantitative PCR (RT-qPCR). Cells in the follicular phase primed with pro-inflammatory cytokines showed higher expression of collagen-related genes (CTGF, COL1A1, COL3A1, and TIMP1) and mesenchymal marker (SLUG, VIM, CDH2, and CDH11) genes; p < 0.05. Cells primed during the mid-luteal overexpressed genes associated with extracellular matrix, processing, and prostaglandin E synthase (MMP2, MMP9, PGR, TIMP2, and PTGES; p < 0.05). There was a notable upregulation of pro-fibrotic miRNAs (miR17, miR21, and miR433) in the follicular phase when the cells were exposed to TGFβ + IL1β, TGFβ + IL6 or TGFβ + IL1β + IL6 + TNFα. Conversely, in cells from the mid-luteal phase, the treatments either did not or diminished the expression of the same miRNAs. On the contrary, the anti-fibrotic miRNAs (miR26a, miR29b, miR29c, miR145, miR378, and mir488) were not upregulated with treatments in the follicular phase. Rather, they were overexpressed in cells from the mid-luteal phase, with the highest regulation observed in TGFβ + IL1β + IL6 + TNFα treatment groups. These miRNAs were also analyzed in the extracellular vesicles secreted by the cells. A similar trend as seen with cellular miRNAs was noted, where anti-fibrotic miRNAs were downregulated in the follicular phase, while notably elevated pro-fibrotic miRNAs were observed in extracellular vesicles originating from the follicular phase. Pro-inflammatory cytokines may amplify the TGFβ signal in the follicular phase resulting in significant upregulation of extracellular matrix-related genes, an imbalance in the metalloproteinases, downregulation of estrogen receptors, and upregulation of pro-fibrotic factors. Conversely, in the luteal phase, there is a protective role mediated primarily through an increase in anti-fibrotic miRNAs, a decrease in SMAD2 phosphorylation, and reduced expression of fibrosis-related genes.

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.

XIST/let-7i/HMGA1 axis maintains myofibroblasts activities in oral submucous fibrosis

Long non-coding RNA XIST promotes the development of various types of head and neck cancers, but its role in the progression of precancerous oral submucous fibrosis (OSF) has not been determined yet. As such, we aimed to examine whether XIST implicates in the regulation of myofibroblast activation. Our results showed that the expression of XIST was upregulated in OSF tissues and fibrotic buccal mucosal fibroblasts (fBMFs), and the silencing of XIST downregulated several myofibroblasts features. We demonstrated that elevation of let-7i after inhibition of XIST may lead to reduced myofibroblast activation. On the contrary, overexpression of high mobility group AT-Hook 1 (HMGA1) following the suppression of let-7i may result in enhanced myofibroblast activities. Moreover, we showed that the suppressive effect of silencing of XIST on myofibroblasts hallmarks was reversed by let-7i inhibition or HMGA1 overexpression, suggesting the pro-fibrotic property of XIST was mediated by downregulation of let-7i and upregulation of HMGA1. These findings revealed that myofibroblast activation of fBMFs may attribute to the alteration of the XIST/let-7i/HMGA1 axis. Therapeutic approaches to target this axis may serve as a promising direction to ameliorate the malignant progression of OSF.

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.

Carcinogenic Effects of Areca Nut and Its Metabolites: A Review of the Experimental Evidence

Oral cancers (OC) are among the most frequent malignancies encountered in Southeast Asia, primarily due to the prevalent habit of betel quid (BQ) and smokeless tobacco use in this region. Areca nut (AN), the primary ingredient in BQ, contains several alkaloids, including arecoline, arecaidine, guvacoline, and guvacine. These have been associated with both the AN abuse liability and carcinogenicity. Additionally, variations in AN alkaloid levels could lead to differences in the addictiveness and carcinogenic potential across various AN-containing products. Recent studies based on animal models and in vitro experiments show cellular and molecular effects induced by AN. These comprise promoting epithelial-mesenchymal transition, autophagy initiation, tissue hypoxia, genotoxicity, cytotoxicity, and cell death. Further, clinical research endorses these undesired harmful effects in humans. Oral submucosal fibrosis, a potentially malignant disease of the oral cavity, is predominantly reported from the geographical areas of the globe where AN is habitually chewed. OC in chronic AN users presents a more aggressive phenotype, such as resistance to anti-cancer drugs. The available evidence on the carcinogenicity of AN based on the findings reported in the recently published experimental studies is discussed in the present review.

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.

An experimental model of the epithelial to mesenchymal transition and pro-fibrogenesis in urothelial cells related to bladder pain syndrome/interstitial cystitis

Background

Suitable in vitro models are needed to investigate urothelial epithelial to mesenchymal transition (EMT) and pro-fibrogenesis phenotype in bladder pain syndrome/interstitial cystitis (BPS/IC). This study is to establish a novel experimental BPS/IC cell model and explore how different concentrations of tumor necrosis factor (TNF)-α influence the EMT and pro-fibrogenesis phenotype of urothelial cells.

Methods

SV-HUC-1 urothelial cells were cultured with 2, 10, or 50 ng/mL TNF-α to mimic chronic inflammatory stimulation. The EMT and pro-fibrogenesis phenotype, including production of collagen I and pro-fibrosis cytokines, were estimated after 72 h of culture.

Results

The bladder urothelial cells of BPS/IC exhibited upregulated vimentin, TNF-α and TNF receptor, downregulated E-cadherin, and increased collagen I. Higher concentrations of TNF-α (10 and 50 ng/mL) produced an obvious mesenchymal morphology, enhanced invasion and migratory capacity, increased expression of vimentin, and decreased expression of E-cadherin. Collagen I was increased in cells treated with 2 and 10 ng/mL TNF-α after 72 h. Secretion of interleukin (IL)-6 and IL-8 was promoted with 10 and 50 ng/mL TNF-α, while that of IL-1β or transforming growth factor-β was unaffected. Slug and Smad2 were upregulated by TNF-α after 72 h. The Smad pathway was activated most strongly with 10 ng/mL TNF-α and Slug pathway activation was positively correlated with the concentration of TNF-α.

Conclusions

Sustained 10 ng/mL TNF-α stimulation induced the EMT and pro-fibrogenesis phenotype resembling BPS/IC in SV-HUC-1 cells. Minor inflammatory stimulation induced the pro-fibrogenesis phenotype while severe inflammatory stimulation was more likely to produce significant EMT changes. Different degrees of activation of the Slug and Smad pathways may underlie this phenomenon.

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.

Arecoline induces epithelial-mesenchymal transformation and promotes metastasis of oral cancer by SAA1 expression

Arecoline, the main alkaloid of areca nut, is well known for its role in inducing submucosal fibrosis and oral squamous cell carcinoma (OSCC), however the mechanism remains unclear. The aim of this study was to establish an arecoline‐induced epithelial‐mesenchymal transformation (EMT) model of OSCC cells and to investigate the underlying mechanisms. CAL33 and UM2 cells were induced with arecoline to establish an EMT cell model and perform RNA‐sequence screening. Luminex multiplex cytokine assays, western blot, and RT‐qPCR were used to investigate the EMT mechanism. Arecoline at a concentration of 160 μg/ml was used to induce EMT in OSCC cells, which was confirmed using morphological analysis, transwell assays, and EMT marker detection. RNA‐sequence screening and Luminex multiplex cytokine assays showed that many inflammatory cytokines (such as serum amyloid A1 [SAA1], interleukin [IL]‐6, IL‐36G, chemokine [CCL]2, and CCL20) were significantly altered during arecoline‐induced EMT. Of these cytokines, SAA1 was the most highly upregulated. SAA1 overexpression induced EMT and promoted the migration and invasion of CAL33 cells, while SAA1 knockdown attenuated arecoline‐induced EMT. Moreover, arecoline enhanced cervical lymph node metastasis in an orthotopic xenograft model of the tongue established using BALB/c nude mice. Our findings revealed that arecoline induced EMT and enhanced the metastatic capability of OSCC by the regulation of inflammatory cytokine secretion, especially that of SAA1. Our study provides a basis for understanding the mechanism of OSCC metastasis and suggests possible therapeutic targets to prevent the occurrence and development of OSCC associated with areca nut chewing.

Effect of metabolic syndrome on incidence of oral potentially malignant disorder: a prospective cohort study in Taiwan

OBJECTIVES

We aimed to assess the effect of metabolic syndrome (MetS) on incident oral potentially malignant disorder (OPMD).

DESIGN

We conducted a prospective cohort study of the Changhua community-based integrated screening (CHCIS) programme and nationwide oral cancer screening programme during the period between 2005 and 2014.

SETTING

CHCIS, Taiwan.

PARTICIPANTS

We enrolled 17 590 participants aged 30 years and older.

MAIN OUTCOMES AND MEASURES

We assessed the impact of MetS on the outcome measured by incident OPMD.

RESULTS

The incidences of OPMD among subjects with and without MetS were 7.68 ‰ and 5.38 ‰, respectively. After adjusting for confounders, subjects with MetS exhibited a statistically greater risk of developing OPMD compared with those who were free of MetS by 33% (adjusted rate ratio, aRR=1.33, 95% CI 1.14 to 1.55). Individual components of MetS still remained significant, including central obesity (aRR=1.22, 95% CI 1.04 to 1.44), hypertriglyceridaemia (aRR=1.26, 95% CI 1.07 to 1.49) and hyperglycaemia (aRR=1.20, 95% CI 1.02 to 1.41). Central obesity and hypertriglyceridaemia were also statistically associated with a subtype of OPMD, namely, leukoplakia.

CONCLUSION

The temporal influence of MetS on the risk of incident OPMD was noted in our prospective cohort study. Therefore, promoting an MetS prevention and control programme might reduce the occurrence of OPMD and oral cancer.

miR-10b regulated by Twist maintains myofibroblasts activities in oral submucous fibrosis

BACKGROUND/PURPOSE

Oral submucous fibrosis (OSF) is an oral precancerous disorder associated with the habit of areca nut chewing. MiR-10b has been shown to be upregulated in the oral cancer cells and induced by Twist. Our previous work has revealed that Twist participated in the pathogenesis of OSF and therefore we aimed to investigate whether Twist/miR-10b axis was involved in the activation of myofibroblast in the oral cavity.

METHODS

The expression levels of miR-10b in OSF tissues and fibrotic buccal mucosal fibroblasts (fBMFs) were examined. Besides, the expression of miR-10b was determined in fBMFs following knockdown of Twist or in BMFs after arecoline stimulation. Myofibroblast activities, including collagen gel contraction, migration and wound healing abilities, as well as the expression of α-SMA were measured in fBMFs treated with miR-10b inhibitor. Last, we investigated whether the effect of Twist overexpression could be reversed by suppression of miR-10b.

RESULTS

MiR-10b expression was overexpressed in both OSF tissues and fBMFs. The silence of Twist resulted in the downregulation of miR-10b in fBMFs and arecoline treatment led to an increase of miR-10b in a dose-dependent manner. Inhibition of miR-10b ameliorated the activation of myofibroblasts and the expression of α-SMA. Moreover, we demonstrated that suppression of miR-10b hindered the increased collagen gel contraction caused by Twist overexpression.

CONCLUSION

MiR-10b upregulation in OSF may be due to the stimulation of areca nut, leading to elevated myofibroblast activation. Our findings showed that the areca nut-induced expression of miR-10b was under the regulation of Twist and inhibition of miR-10b may provide a direction for treatment of OSF.

Multifaceted Mechanisms of Areca Nuts in Oral Carcinogenesis: the Molecular Pathology from Precancerous Condition to Malignant Transformation

Oral cancer is one of the most frequent malignant diseases worldwide, and areca nut is a primary carcinogen causing this cancer in Southeast Asia. It has been widely reported that areca nut induced several cytotoxic effects in oral cells, including ROS generation, inflammation, tissue hypoxia, DNA damage, and cell invasion. Recently, through chronic exposure model, more extensive pathological effects due to areca nut have been found. These include the induction of autophagy, promotion of epithelial- mesenchymal transition, and facilitation of cancer stemness conversion. Clinical findings support these adverse effects. Oral submucosal fibrosis, a premalignant condition, is prevalent in the area with habitual chewing of areca nuts. Consistently, oral cancer patients with habitual chewing areca nut exhibit more aggressive phenotypes, including resistance to chemo-radiotherapy. In this review, we comprehensively discuss and concisely summarize the up-to-date molecular and cellular mechanisms by which areca nuts contribute to malignant transformation. This review may provide critical information regarding clinical applications in risk assessment, disease prevention, diagnosis, and personalized therapeutics for areca nut-induced oral malignancy.

Oral Submucous Fibrosis: A Review on Etiopathogenesis, Diagnosis, and Therapy

Oral submucous fibrosis (OSF) is characterized by abnormal collagen deposition. It is a precancerous disorder and transforms into a malignant tumor in 1.5–15% of all cases. Symptoms include submucous fibrosis, ulceration, xerostomia, a burning sensation, and restricted mouth opening. All of these greatly interfere with patient quality of life. The present review introduces OSF from a molecular perspective and summarizes what is known about its underlying mechanisms, diagnostic biomarkers, and therapeutic interventions. In addition to the aggressive treatment of OSF, its prevention is also important. Future research should, therefore, focus on improving the oral health literacy of the patients susceptible to OSF.

Arctigenin Reduces Myofibroblast Activities in Oral Submucous Fibrosis by LINC00974 Inhibition

Oral submucous fibrosis (OSF) is an oral precancerous condition associated with the habit of areca nut chewing and the TGF-β pathway. Currently, there is no curative treatment to completely heal OSF, and it is imperative to alleviate patients’ symptoms and prevent it from undergoing malignant transformation. Arctigenin, a lignan extracted from Arctium lappa, has been reported to have a variety of pharmacological activities, including anti-fibrosis. In the present study, we examined the effect of arctigenin on the cell proliferation of buccal mucosal fibroblasts (BMFs) and fibrotic BMFs (fBMFs), followed by assessment of myofibroblast activities. We found that arctigenin was able to abolish the arecoline-induced collagen gel contractility, migration, invasion, and wound healing capacities of BMFs and downregulate the myofibroblast characteristics of fBMFs in a dose-dependent manner. Most importantly, the production of TGF-β in fBMFs was reduced after exposure to arctigenin, along with the suppression of p-Smad2, α-smooth muscle actin, and type I collagen A1. In addition, arctigenin was shown to diminish the expression of LINC00974, which has been proven to activate TGF-β/Smad signaling for oral fibrogenesis. Taken together, we demonstrated that arctigenin may act as a suitable adjunct therapy for OSF.