Observations on the effect of areca nut extracts on oral fibroblast proliferation

Green-Synthesized Silver Nanoparticles: Antifungal and Cytotoxic Potential for Further Dental Applications

Fungal infections caused by Candida albicans (C. albicans) are one of the most prevalent types of oral disorders in the elderly. It has been reported that drug resistance to fungal pathogens poses a severe risk to global healthcare systems and public health. Therefore, the goal of this work is to investigate the cytotoxic and antifungal properties of silver nanoparticles (AgNPs) produced using three different natural extracts: Berzelia lanuginose, Helichrysum cymosum, and Searsia crenata. According to the UV-Vis results, the synthesized AgNPs via B. lanuginose, H. cymosum, and S. crenata show surface plasmonic resonance (SPR) peaks at 430, 440, and 428 nm, respectively. HR-TEM revealed different shapes for the nanoparticles within the size ranges of 16-20, 31-60, and 57-72 nm for B. lanuginose, H. cymosum, and S. crenata, respectively. Using a human oral fibroblast cell line, the cytotoxicity of both AgNPs and plant extracts was tested at concentrations of 0.007, 0.012, 0.025, and 0.062 mg/mL (buccal mucosa fibroblasts). The antifungal activity showed growth inhibition zones of approximately 18 mm, 18.67 mm, and 18.33 mm for the AgNPs conjugated with B. lanuginose, H. cymosum, and S. crenata, respectively. For the studied samples, the minimum inhibitory concentration (MIC₅₀) was less than 0.015 mg/mL. The AgNPs exhibited antifungal activity that was concentration- and size-dependent. The results of this study offer new insights into the cytotoxicity and antifungal activity of the green-synthesized AgNPs.

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.

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

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

Estimation and correlative study of salivary nitrate and nitrite in tobacco related oral squamous carcinoma and submucous fibrosis

Oral cancer is one of the ten leading cancers of the world. In India, it is one of the common cancers and is an important public health problem. Tobacco plays significant role in etiology of oral squamous carcinoma. Tobacco which is chewed or smoked contains many alkaloids which are known carcinogens. Oral submucous fibrosis (OSMF) is a disease of the Indian subcontinent, which through immigration has a worldwide distribution. Betel nut chewing plays significant role in etiology of OSMF. The nut alkaloids have been shown experimentally to result in stimulation of collagen synthesis by fibroblasts in vitro, which can induce precancerous conditions.

Arecanut as an emerging etiology of oral cancers in India

Arecanut (AN) usage is widespread in Asian countries, especially India and Taiwan. The incidence of oral cancer is increasing day by day, but there is no exponential increase with tobacco usage. Especially in the country like Taiwan where betel quid mostly do not contain tobacco, AN can be correlated with the increased incidence of cancer. There are different studies in the literature about AN and oral cancer but none of them have concluded with the definite pathway for carcinogenesis. The present paper includes reviews of the literature for AN and oral cancer and summarizes the possible mechanisms associated with AN-induced carcinogenesis; and we have also tried to propose pathway of carcinogenesis.

Arecoline induced cell cycle arrest, apoptosis, and cytotoxicity to human endothelial cells

Betel quid (BQ) chewing is a common oral habit in South Asia and Taiwan. BQ consumption may increase the risk of oral squamous cell carcinoma (OSCC), oral submucous fibrosis (OSF), and periodontitis as well as systemic diseases (atherosclerosis, hypertension, etc.). However, little is known about the toxic effect of BQ components on endothelial cells that play important roles for angiogenesis, carcinogenesis, tissue fibrosis, and cardiovascular diseases. EAhy 926 (EAHY) endothelial cells were exposed to arecoline, a major BQ alkaloid, for various time periods. Cytotoxicity was estimated by 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay. The cell cycle distribution of EAHY cells residing in sub-G0/G1, G0/G1, S-, and G2/M phases was analyzed by propidium iodide staining of cellular DNA content and flow cytometry. Some EAHY cells retracted, became round-shaped in appearance, and even detached from the culture plate after exposure to higher concentrations of arecoline (> 0.4 mM). At concentrations of 0.4 and 0.8 mM, arecoline induced significant cytotoxicity to EAHY cells. At similar concentrations, arecoline induced G2/M cell cycle arrest and increased sub-G0/G1 population, a hallmark of apoptosis. Interestingly, prolonged exposure to arecoline (0.1 mM) for 12 and 21 days significantly suppressed the proliferation of EAHY cells, whereas EAHY cells showed adaptation and survived when exposed to 0.05 mM arecoline. These results suggest that BQ components may contribute to the pathogenesis of OSF and BQ chewing-related cardiovascular diseases via toxicity to oral or systemic endothelial cells, leading to impairment of vascular function. During BQ chewing, endothelial damage may be induced by areca nut components and associate with the pathogenesis of OSF, periodontitis, and cardiovascular diseases.

Ultrastructural and hormonal changes in the pineal-testicular axis following arecoline administration in rats

Arecoline is an alkaloid of betel nut of Areca catechu. Betel nut is chewed by millions of people in the world and it causes oral and hepatic cancers in human. It has therapeutic value for the treatment of Alzheimer and schizophrenia. Arecoline has immunosuppressive, mutagenic and genotoxic effects in laboratory animals. It also affects endocrine functions. The objective of this study was to investigate the effects of arecoline on pineal-testicular axis in rats. Since pineal activity is different between day and night, the current study is undertaken in both the photophase and scotophase. The findings were evaluated by ultrastructural and hormonal studies of pineal and testicular Leydig cells, with quantitations of fructose and sialic acid of sex accessories. Arecoline treatment (10 mg/kg body weight daily for 10 days) caused suppression of pineal activity at ultrastructural level by showing dilatation of the cisternae of the rough endoplasmic reticulum (RER), large autophagosome-like bodies with swollen mitochondrial cristae, numerous lysosomes, degenerated synaptic ribbons and reduced number of synaptic-like microvesicles. Moreover, pineal and serum N-acetylserotonin and melatonin levels were decreased with increased serotonin levels in both the gland and serum. In contrast, testicular Leydig cell activity was stimulated with abundance of smooth endoplasmic reticulum (SER), electron-dense core vesicles and vacuolated secretory vesicles, and increased testosterone level in the arecoline recipients. Consequently, the testosterone target, like prostate, was ultrastructurally stimulated with abundance of RER and accumulation of secretory vesicles. Fructose and sialic acid concentrations were also significantly increased respectively in the coagulating gland and seminal vesicle. These results were more significant in the scotophase than the photophase. The findings suggest that arecoline inhibits pineal activity, but stimulates testicular function (testosterone level) and its target organs presumably via muscarinic cholinergic receptor in rats.

Development of an in vivo mouse model to study oral submucous fibrosis

BACKGROUND

Epidemiological data have shown an association of areca nut chewing with oral submucous fibrosis (OSF). Experimental evidence to confirm this has been limited. Fibrosis-promoting activity of areca nut was tested in an animal model.

METHOD

Buccal mucosa of a group of 20 female BALB/c strain mice, 10-12 weeks of age, was treated twice daily 6 days per week with topical application of aqueous areca nut extracts for 300-600 days. A control group (n = 20) was treated with 50 mM NaCl. The influence of areca nut on the oral epithelium and connective tissue was recorded semiquantitatively by light microscopy.

RESULTS

The areca nut-treated oral epithelium showed progressive changes in epithelial thickness leading to atrophy, increased cellularity of fibroblasts, fibrosis of connective tissue, focal infiltration of inflammatory cells and muscle atrophy. On killing after 600 days of treatment, the scores on cellularity, inflammation and muscle atrophy were significantly different to the control group (P = 0.03).

CONCLUSION

The study provides further evidence that areca nut contributes to the development of OSF in treated animals. The model has the potential to test synergism of areca nut with other carcinogens and any therapeutic interventions.

Areca nut extracts modulated expression of alkaline phosphatase and receptor activator of nuclear factor kappaB ligand in osteoblasts

OBJECTIVES

Areca chewers have a higher prevalence of periodontal diseases than non-chewers. This study was to determine the possible effects of ripe areca nut extracts (rANE) on viability and gene expression of alkaline phosphatase (ALP), receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in human osteoblasts.

METHODS

The effects of rANE on cell viability of osteoblast-like MG63 cells were determined using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) that measures metabolic activity. Gene expression of ALP, RANKL and OPG was examined using reverse transcription-polymerase chain reaction. ALP activity and RANKL protein were further examined using substrate assay and confocal laser scanning microscopy, respectively.

RESULTS

Relative viability was reduced to approximately 50% when 25 microg/ml of rANE was used. The expression of OPG mRNA in MG63 cells was not altered by rANE. However, decreased levels of mRNA and enzyme activity of ALP were observed. Moreover, the expressions of mRNA and protein of RANKL were stimulated by rANE in a dose-dependent manner.

CONCLUSIONS

The rANE affected morphology and viability of osteoblasts. We also present novel evidence demonstrating that areca nut may compromise the periodontal health of areca chewers by suppression of ALP gene expression and elevation of RANKL gene expression in osteoblasts.

Inhibitory Effects of Areca Nut Extracts on Phagocytosis ofActinobacillus actinomycetemcomitansATCC 33384 by Neutrophils

BACKGROUND

Areca quid chewers have a higher prevalence of periodontal disease than non-chewers. Little is known about the influence of areca quid on the immune system. This study was to determine the possible effects of the areca nut on phagocytic activity of human neutrophils.

METHODS

Aqueous extracts of ripe areca nut without husk (rANE), fresh and tender areca nut with husk (tANE), a major alkaloid (arecoline), and a phenolic component ([+]-catechin) of areca nut were examined for their effects on cellular viability using trypan blue exclusion assay. The possible effects on the phagocytic activity of neutrophils against a periodontal pathogen, Actinobacillus actinomycetemcomitans ATCC 33384, were determined using flow cytometry and confocal laser scanning microscopy.

RESULTS

At the concentrations tested, rANE, tANE, arecoline, and (+)-catechin did not significantly affect viability of neutrophils. However, rANE, tANE, arecoline, and (+)-catechin inhibited the phagocytic activity of neutrophils in a dose-dependent manner. Approximately 50% of the relative phagocytic activity of neutrophils was affected when 50 microg/ml of rANE, 400 microg/ml of tANE, 20,000 microg/ml of arecoline, or 2,500 microg/ml of (+)- catechin was used. Decreased levels of internalized fluorescent bacteria were also demonstrated. However, arecoline or (+)-catechin alone could not be used to explain the inhibitory effects observed for rANE and tANE.

CONCLUSIONS

Components of areca nut reduced the uptake of A. actinomycetemcomitans ATCC 33384 by human neutrophils. The inhibition of areca nut on phagocytosis of neutrophils may be one possible mechanism by which the areca nut compromises the periodontal health of areca quid chewers.

Alterations in expression of retinoid receptor beta and p53 in oral submucous fibrosis

OBJECTIVE

Knowledge of the molecular pathogenesis of oral submucous fibrosis (OSF), a potentially malignant condition with high risk of transition to oral cancer, is meagre. Alterations in the expression of retinoic acid receptor beta (RARbeta) and tumor suppressor gene, p53 are early events in oral tumorigenesis. The aim of this study was to investigate the alterations in the expression of RARbeta and p53 in OSF lesions and determine their association with disease pathogenesis.

METHODS

The expression of RARbeta and p53 proteins was analyzed by immunohistochemistry in 50 cases of OSF and 30 histologically normal oral tissues.

RESULTS

No detectable RARbeta expression was observed in 35 of 50 (70%) OSF cases. p53 protein accumulation was observed in 24 of 50 (48%) OSF cases analyzed. Thirty-six percent OSF lesions showed loss of RARbeta and p53 overexpression. Interestingly, 41 of 50 (82%) of OSF lesions showed altered expression of at least one of these two proteins.

CONCLUSION

Altered expression of either RARbeta or p53 in majority of OSF lesions suggests their association with disease pathogenesis and warrants follow-up to determine whether OSF lesions harboring concomitant alterations in RARbeta and p53 are at a high risk of transition to malignancy.

Regulation of cell growth by selective COX-2 inhibitors in oral carcinoma cell lines

Evidence indicates that NSAIDs that inhibit prostaglandin (PG) synthesis can reduce the incidence of colorectal cancers and that inhibition of cyclooxygenase-2 (COX-2) may be the underlying mechanism. The objective of this study was to investigate this putative mechanism by examining the effect of selective COX-2 inhibitors (Celebrex, DFU, NS-398) and COX-1 inhibitors (Aspirin) on the growth of two human oral carcinoma cell lines (OEC-M1 and KB) and one normal fibroblast cell line (NF). We found that the growth of OEC-M1 cells could be significantly inhibited by DFU concentrations above 30 microM (31%) after 4 days, and above 50 microM (35%) after 2 days in culture; by Celebrex at concentrations above 20 microM (52%) after 6 days, above 30 microM (36%) after 5 days, and above 40 microM (33%) after 4 days in culture; and by NS-398 above 1 microM (30%) after 6 days, and above 10 microM (35%) after 5 days in culture. The growth of KB cells could be significantly inhibited by DFU concentrations above 10 microM (33%) after 6 days, above 20 microM (35%) after 4 days in culture; and by Celebrex at concentrations above 10 microM (33%) after 5 days, and above 50 microM (30%) after 4 days in culture; and by NS-398 above 1 microM (45%) after 5 days, above 20 microM (36%) after 4 days in culture. The growth of NF cells could be significantly inhibited by DFU above 30 microM (45%) after 6 days, and above 40 microM (32%) after 3 days in culture, and by Celebrex at concentrations above 10 microM (42%) after 6 days, above 30 microM (31%) after 4 days, above 50 microM (32%) after 3 days in culture, and by NS-398 above 0.1 microM (35%) after 4 days, and above 1 microM (32%) after 3 days in culture. The growth-inhibitory concentration (IC50) values for DFU on OEC-M1, KB, and NF cells were about 39.1, 14.8, and 42.9 microM at 144 h, respectively, and on KB was about 45.2 microM at 120 h. The IC50 values for Celebrex on OEC-M1, KB, and NF cells were about 19.1, 8.6, and 15.8 microM at 144 h, respectively, and on KB and NF were about 27.7 and 35.3 microM, respectively, at 120 h. The IC50 values for NS-398 on OEC-M1, KB, and NF were about 18.9, 0.7 and 1 microM, respectively, at 144 h; on KB and NF values were about 10.8 and 1.4 microM, respectively, at 120 h and on KB and NF were about 26.6 and 4.1 microM, respectively, at 96 h. The results show that the growth of these cell lines is inhibited by three COX-2 selective inhibitors but not by any COX-1 selective inhibitors. These findings suggest that COX-2 may play an important role in the generation of biochemical mediators that stimulate the growth of human oral cancer and normal fibroblast cell lines.

Modulation of KGF-1 gene expression in oral fibroblasts by ripe areca nut extract

BACKGROUND

Areca chewing is a common habit of Asians, leading to a high propensity for a variety of oral diseases in this population. This research aimed to study the expression level of genes in oral fibroblast cell lines in response to exposure to ripe areca nut extract (rANE).

METHODS

Fifteen oral fibroblast cell lines obtained from individuals aged 20-77 years were established. Treatment of a cell line with 40 micro g/ml rANE for 24 h was performed to achieve RNA for cDNA microarray analysis.

RESULTS

Among some 320 genes exhibiting detectable expression levels, 14 were up-regulated and 26 were down-regulated more than 2.5-fold. Semi-quantitative RT-PCR analysis suggested that up-regulation of IL-6 expression and down-regulation of PDGFR, APP-1 and KGF-1 expressions in multiple cell lines assayed, were compatible with the results of the microarray analysis. Using quantitative real-time RT-PCR analysis, a remarkable down-regulation of KGF-1 expression in response to 40 microg/ml rANE, ranging 1.5-ninefold as compared to controls, was found in 60% (9/15) of the cell lines.

CONCLUSION

This study established a novel toxicogenomic database for rANE. The down-regulation of KGF-1 expression in oral fibroblast cell lines potentially impairs the proliferation of overlying keratinocytes, which could partially explain the frequent epithelial atrophy observed in chronic areca chewers in vivo.

Genotoxic effect of raw betel-nut extract in relation to endogenous glutathione levels and its mechanism of action in mammalian cells

The mutagenic and carcinogenic potency of betel-nut components is well established. This study was undertaken to determine the genotoxic potency of an aqueous extract of raw betel nut (AEBN) in relation to the endogenous glutathione (GSH) level in mouse bone marrow cells (BMC) and human peripheral blood lymphocytes (PBLs), and to find out whether arecoline (ARC), an alkaloid of betel nut, could generate reactive oxygen species (ROS) in these cells. It was observed that AEBN has genotoxic properties, which is further enhanced by depletion of endogenous GSH levels. However, the degree of enhancement varies with the type of parameter and cell system studied. The present data indicate that the generation of ROS by ARC could partially contribute to the induction of chromosomal aberrations (CAs), since the frequency of ARC-induced CAs was reduced either by post-treatment with superoxide dismutase (SOD) or in anoxic conditions. However, the induction of sister chromatid exchanges (SCEs) probably involves p53-dependent changes in cell proliferation and allowing some repair of DNA damage. The extent of damage for each parameter was higher when the mice were exposed to AEBN for 30 days than 5 days. Longer exposure showed higher level of p53 expression in mouse BMC, which could block the damaged cells from proliferation and allow the cells to repair the DNA damage.

The effect of betel nut extract on cell growth and prostaglandin endoperoxide synthase in human epidermoid carcinoma cells

The objective of this study was to find out whether prostaglandin endoperoxide synthase (PHS) involves the action of betel nut extract (BNE) on the growth of oral cancers. Therefore, growth and PHS activity were examined in two human oral carcinoma cell lines (OEC-M1 and KB) and one normal fibroblast cell line (NF) in the presence of increasing BNE concentration. BNE at concentrations above 50 microg/ml significantly inhibited the cell growth of OEC-M1 after 72 h in culture, of KB and NF after 48 h in culture. The IC50 of BNE in OEC-M1, KB and NF at 24 h in culture was about 406, 37.5 and 140 microg/ml respectively. PHS activity in OEC-M1 was significantly increased by low BNE concentrations (50 microg/ml, 114%; 100 microg/ml, 33%; 150 microg/ml, 30%) but significantly reduced at higher BNE concentrations (300 microg/ml, 33%; 500 microg/ml, 61%). The PHS activity in KB was significantly inhibited by BNE and this effect was intensified as concentrations increased (50 microg/ml, 31%; 100 microg/ml, 24%; 150 microg/ml, 43%; 300 microg/ml, 60%; 500 microg/ml, 92%). Similar to that in OEC-M1, the PHS activity in NF was significantly increased at low BNE concentrations (50 microg/ml, 139%; 100 microg/ml, 87%;150 microg/ml, 77%) but reduced at higher concentrations (300 microg/ml, 55%; 500 microg/ml, 72%). The PHS activity in all cell lines was almost completely blocked by indomethacin (5 x 10(-6) M). We conclude that these findings suggest that PHS may be an important biochemical mediator of the effect of BNE on the growth of two human oral carcinoma cell lines.

The oral health consequences of chewing areca nut

Deleterious effects of areca nut on oral soft tissues are published extensively in the dental literature. Its effects on dental caries and periodontal tissues, two major oral diseases, are less well researched. Areca-induced lichenoid lesions mainly on buccal mucosa or tongue are reported at quid retained sites. In chronic chewers a condition known as betel chewer's mucosa, a discoloured areca nut-encrusted change, is often found where the quid particles are retained. Areca nut chewing is implicated in oral leukoplakia and submucous fibrosis, both of which are potentially malignant in the oral cavity. Oral cancer often arises from such precancerous changes in Asian populations. In 1985 the International Agency for Research on Cancer concluded that there is limited evidence to conclude that areca chewing may directly lead to oral cancer. There is, however, new information linking oral cancer to pan chewing without tobacco, suggesting a strong cancer risk associated with this habit. Public health measures to quit areca use are recommended to control disabling conditions such as submucous fibrosis and oral cancer among Asian populations.

Role of areca nut in betel quid-associated chemical carcinogenesis: current awareness and future perspectives

Betel quid (BQ)-chewing is a popular oral habit with potential links to the occurrence of oral cancer. Many of the literature-based studies reveal that areca nut (AN) extract may demonstrate mutagenic and genotoxic effects, in addition to inducing preneoplastic as well as neoplastic lesions in experimental animals. Areca nut should, thus, be highly suspected as a human carcinogen. Toxicity studies relating to AN-contained polyphenols and tannins are not conclusive, with both carcinogenic and anti-carcinogenic effects being reported. The mutagenicity and genotoxicity of areca alkaloids has been detected by many short-term assays. However, their genotoxicity to oral fibroblasts and keratinocytes, the target cells of BQ, has not been identified. It would thus appear that AN toxicity is not completely due to its polyphenol, tannin and alkaloid content. The single agent which is responsible for AN carcinogenicity awaits further clarification. Reactive oxygen species produced during auto-oxidation of AN polyphenols in the BQ-chewer's saliva, are crucial in the initiation and promotion of oral cancer. Nitrosation of areca alkaloids also produces AN-specific nitrosamines, that have been demonstrated to be mutagenic, genotoxic and are capable of inducing tumors in experimental animals. Arecaidine and AN extract are further suggested to be tumor promoters. Antioxidants such as glutathione and N-acetyl-L-cysteine can potentially prevent such AN-elicited cytotoxicity. Further studies are needed to delineate the metabolism of AN ingredient and their roles in the multi-step chemical carcinogenesis, in order to enhance the success of the future chemoprevention of oral cancer and oral submucous fibrosis.

The upregulation of lysyl oxidase in oral submucous fibrosis and squamous cell carcinoma

Lysyl oxidase (LO) takes part in the initial steps of converting soluble monomers of collagen and elastin into insoluble fibres in the extracellular matrix. We have studied the immunolocalization of LO as a marker of fibrogenesis in oral submucous fibrosis (OSF). Oral biopsies from 13 subjects with OSF, 6 with histologically confirmed squamous cell carcinoma (SCC) arising in OSF and 10 SCC nonrelated to OSF, were examined. Strong positive staining was observed in 7/13 OSF samples in the cytoplasmic processes of fibroblasts and extracellularly in the upper third of the lamina propria. Furthermore, LO was found to co-localize in the areas stained strongly for collagen and elastin by histochemical stains. Examination of SCC tissues showed localization of LO adjacent to invading epithelial islands as evidence of a stromal reaction both in carcinomas arising from OSF and in SCC from non-OSF cases. These findings suggest that upregulation of LO may be an important factor in the pathogenesis of OSF and in the early stromal reaction of oral cancer.

Chemical composition and toxicity of Taiwanese betel quid extract

In this genotoxic study, the Ames Salmonella microsome test showed that an aqueous extract of betel quid did not induce mutagenicity in Salmonella typhimurium strains TA98 and TA100. Mammalian cell studies (Chinese hamster ovary K1 cell; CHO-K1 cell) revealed that only higher concentrations (100 and 1000 microg/ml) of aqueous extract weekly increased the frequencies of sister-chromatid exchange (SCE) in the absence of S9. Animal (male Sprague-Dawley rat) studies showed that low-dose feeding (0.53 g dry aqueous extract/kg diet) significantly increased the activities of glutathione (GSH) peroxidase and cytoplasmic glutathione S-transferase (cGST) of liver, high-dose feeding (26.5 g dry aqueous extract/kg diet) lowered the contents of GSH and total glutathione. The effect of an aqueous extract of betel quid on the oxidation of 2'-deoxyguanosine (2'-dG) to 8-hydroxy-2'-deoxyguanosine (8-OH-dG) evaluated that this aqueous extract may act as a pro-oxidant at lower dosage and may be dependent on the iron ions in the model system. However, the aqueous extract of betel quid showed antioxidant activity at higher doses by the ability of the scavenging effect of the hydroxyl radicals.

Inhibition of the synthesis of eicosanoid-like substances in a human oral cancer cell line by interferon-gamma and eicosapentaenoic acid

The objectives were to examine the production of eicosanoids in a Chinese human oral cancer cell line (OEC-M1) and to test the effects of interferon-gamma (IFN-gamma), eicosapentaenoic acid (EPA) and enzyme inhibitors on this biosynthesis. The eicosanoids were identified by reverse phase-high performance liquid chromatography. Two predominant peaks appeared in the chromatograms. One compound (P-1) was identified by ultraviolet absorption at a lambda(max) of 278nm with shoulders at 272 and 284nm. The other compound (P-2) was identified by ultraviolet absorption at a lambda(max) of 284 nm with shoulders at 278 and 290 nm. The production of P- was significantly inhibited by the addition of IFN-gamma (200 and 400 U/ml), and EPA (10 to 40 microM). It was only partially inhibited (p < 0.05) by indomethacin (INDO) (0.5 and 1 microM), nordihydroguaiaretic acid (NDGA) (30 and 60 microM/ml), and eicosa-5,8,11,14-tetraynoic acid (ETYA) (20-60 microM). It was almost completely inhibited by indomethacin (2 and 3 microM), and dexamethasone (0.6 and 6 microM). The production of P-2 was almost completely inhibited by IFN-gamma (200 and 400 U/ml), and partially inhibited (p < 0.05) by EPA (10 and 20 microM), NDGA (30 and 60 microM), ETYA (20 and 40 microM), dexamethasone (0.6 and 6 microM). The production of both peaks was significantly reduced by excluding arachidonic acid (AA), and almost completely inhibited by heating at 100 degrees C for 10 min during incubation. These results demonstrate that two eicosanoid-like compounds are synthesized by the OEC-M cell line and that their production can be modulated by IFN-gamma, EPA, indomethacin, NDGA, ETYA, and dexamethasone.

p53 aberrations in oral submucous fibrosis and oral squamous cell carcinoma detected by immunocytochemistry and PCR-SSCP

An archival series of oral biopsies from Karachi, Pakistan, consisting of 21 cases of oral submucous fibrosis (OSF) and 27 cases of squamous cell carcinoma (SCC), of which 6 had arisen from OSF, were used to examine the aberrations in the structure and expression of the p53 tumour suppressor gene. The PCR-SSCP method was used for mutation analysis of exons 2-9, and (over)expression of p53 protein was detected by immunocytochemistry using monoclonal antibody DO 7. Positive immunostaining was observed in 15/20 (75%) of OSF specimens, 3/6 (50%) of SCC arising from OSF and 14/21 (67%) of SCC not arising from OSF. Mobility shifts in SSCP indicative of a mutation in p53 or loss of heterozygosity (deletion of a band) were seen in 13/21 cases of OSF and 15/27 cases of SCC. There was concordance between immunocytochemistry and SSCP results in a majority (33/48) of samples. Though the number of analysed SCC cases arising from OSF was limited, the results suggest that p53 mutation/protein stabilisation may play a part in the pathogenesis of OSF and its progression to SCC.

The fibroblast population in oral submucous fibrosis

The purpose of the investigation was to compare the morphology of fibroblasts cultured from healthy oral mucosa and mucosa of patients with oral submucous fibrosis (OSF) and to collate the occurrence of cell types of similar morphology. Cells cultured from biopsy specimens from the buccal mucosa of six subjects who did not chew the areca nut and six patients with OSF who chewed areca nut were grown according to standard techniques. Ninety cells per cell line were recorded daily for 8 days, classified into types F1, F2 and F3 according to their morphology, and the results statistically analyzed. We found that there was a relative increase of F3 cells in relation to F1 cells in OSF, resulting in the ratio of F3 to F1 cells being significantly larger in OSF than the ratio in the controls. As it has been reported that F3 cells in rat connective tissues produce significantly more collagen types I and III than F1 cells, we concluded that a change of fibroblast population has occurred in OSF and that this relative increase of F3 cells in humans, which could be committed to the production of large quantities of collagen, can be an explanation for the excessive collagen formation in OSF.

Studies on promoting activity of Taiwan betel quid ingredients in hamster buccal pouch carcinogenesis

Previous studies indicated that Taiwan betel quid is a promoter rather than an initiator during the carcinogenesis of hamster buccal pouch carcinoma. The maximum promoting activity can be demonstrated 24 weeks after betel quid implantation, following an initial application of 0.5% DMBA (7,12-dimethyl benzanthracene) three times per week for 4 weeks. In the present study, components of Taiwan betel quid and its additives (dry betel nut fibre, piper betel, slaked lime, cold aqueous extract, and hot aqueous extract) were applied respectively or in various combinations to investigate their promoting activity. One hundred and thirty Syrian hamsters were divided into 13 groups based on different combinations of the betel quid ingredients applied. The incidence of tumours in the hamster buccal pouch was significantly higher in groups exposed to dry betel nut fibre (P < 0.01) and cold aqueous extract (P < 0.05). The results indicate that betel nut fibre and cold aqueous extract are the major components of betel quid that may promote carcinogenesis in the hamster buccal pouch.

Inhibition of the migration, attachment, spreading, growth and collagen synthesis of human gingival fibroblasts by arecoline, a major areca alkaloid, in vitro

Because betel quid (BQ) chewing has been linked to a higher prevalence of periodontal diseases, the pathobiological effects of arecoline, a main alkaloid found in areca nut, were investigated in cultured human gingival fibroblasts. At concentrations higher than 0.4 mM, arecoline inhibits cell attachment, cell spreading and cell migration in a dose-dependent manner. These inhibitory effects were associated with intracellular depletion of glutathione (GSH). At concentrations of 0.4 mM and 1 mM, arecoline depleted about 26% and 45% of GSH after 2 h incubation. Exposure of cells to arecoline at concentrations lower than 0.4 mM for 2 h showed no significant decrease in either cell viability or intracellular GSH. However, incubation of cells for 24 h in 1 mM are colined decreased the cell numbers to only 35% of those in the untreated control. Arecoline also decreased cell growth and collagen synthesis in a dose-dependent manner. Because of repeated and long-term exposure to arecoline, BQ chewers could be more susceptible to periodontal damage and less responsive to new attachment procedures.

Minimal arecaidine concentrations showing a promotion effect during DMBA-induced hamster cheek pouch carcinogenesis

The purpose of the present study was to determine the minimal arecaidine concentrations showing a synergistic effect on DMBA-induced hamster cheek pouch carcinogenesis. One hundred and twelve male adult Syrian golden hamsters were divided into 16 groups, each containing seven animals. After eight weeks of DMBA initiation and then four weeks of arecaidine promotion, 100% tumor incidence was found with arecaidine concentrations of 400 micrograms/ml and 500 micrograms/ml; average tumor numbers were 1.86 +/- 0.63 and 1.86 +/- 0.93 respectively (P < 0.05). After four weeks of DMBA and a subsequent eight weeks of arecaidine painting, all hamsters developed visible tumors with arecaidine concentrations of 900 micrograms/ml and 1000 micrograms/ml; average tumor numbers were 1.86 +/- 0.82 and 2.14 +/- 1.09 respectively (P < 0.05). The tumor dimensions varied little and differences were not statistically significant. Without DMBA pretreatment, regardless of the high arecaidine concentrations (1000 micrograms/ml, 2000 micrograms/ml and 3000 micrograms/ml) applied, no visible tumor growth was observed; only hyperkeratosis and inflammation could be discerned histologically. Thus, the minimal concentrations of arecaidine displaying a synergistic effect in the DMBA-induced hamster cheek pouch of carcinogenesis were found to be 400 micrograms/ ml applied for four weeks after eight weeks of DMBA application, and 900 micrograms/ml applied for eight weeks after four weeks of DMBA painting. These findings may be useful for other studies concerning the tumorgenicity of arecaidine.

Growth of oral and skin fibroblasts from patients with oral submucous fibrosis

The purpose of the investigation was to evaluate and compare the proliferation (growth) of mouth fibroblasts and skin fibroblasts from patients with oral submucous fibrosis (OSF). Material comprised fibroblasts from fibrous bands situated in the buccal mucosa and from the inner aspect of the forearm of 8 patients with classic features of OSF as well as fibroblasts from 6 buccal mucosa and 8 skin biopsy specimens from healthy non-areca nut chewing individuals. Cells were cultured for 8 days according to standard techniques. Their growth was monitored daily, under optimal conditions as well as exposure to concentrations of arecoline. The data were analyzed using regression analysis, analysis of variance and the Kruskal-Wallis test. We found no statistically significant differences between the proliferation patterns of oral and skin fibroblasts from patients or between those from patients and controls. The reaction of the cells exposed to concentrations of arecoline was similar; at low concentrations (0.1-10 micrograms/ml) normal growth was maintained, while 100 micrograms/ml inhibited growth. It is concluded that fibroblasts from mouths affected by OSF have proliferation patterns which fall within normal parameters, that the excessive collagen formation in established OSF is not due to increased fibroblast proliferation and that arecoline does not stimulate fibroblast proliferation.