Genotoxic and Non-genotoxic Effects of Betel Quid Ingredients on Oral Mucosal Fibroblasts in vitro

Abstract

To understand the role of betel quid (BQ) in the pathogenesis of oral submucous fibrosis (OSF) and oral cancer, we used DNA damage, cytotoxicity, and cell proliferation assays to study the pathobiological effects of aqueous extracts of three BQ constituents [betel nut (Areca catechu, BN), inflorescence of Piper betle (IPB), and lime], one BN alkaloid (arecoline), and one BN polyphenol [(+)-catechin] on cultured oral mucosal fibroblasts. Extracts of BN and IPB induced DNA strand break formation in a dose-dependent manner. Extracts of BN and IPB, (+)-catechin, and arecoline decreased cell survival and proliferation in a dose-dependent manner. However, aqueous extract of lime (50-800 micrograms/mL) increased cell proliferation by 20-40%. These results indicate that BQ contains not only genotoxic and cytotoxic agents, but also compounds which stimulate cell proliferation. These compounds may act synergistically in the pathogenesis of OSF and oral cancer in BQ chewers. In addition, five anti-oxidants [glutathione (GSH), cysteine, mannitol, catalase, and superoxide dismutase (SOD)] were tested for their protective effects against the cytotoxicity of BQ constituents. GSH (1.95 and 2.6 mmol/L) and cysteine (4 and 8 mmol/L) prevented the arecoline-induced cytotoxicity. In contrast, mannitol, catalase, and SOD did not decrease the arecoline-induced cytotoxicity. These results indicate that thiol depletion, but not the attack of oxygen free radicals, could be the mechanism for arecoline cytotoxicity. GSH could also protect cells from the cytotoxicity of IPB extract. Increasing dietary intake of GSH-rich foods or dietary supplements of GSH may have chemopreventive potential to reduce BQ-associated oral lesions.

Evaluation of salivary and serum lipid peroxidation, and glutathione in oral leukoplakia and oral squamous cell carcinoma

“…In contrast to the present study, oral pre-cancer and cancer patients have reported increased serum levels of GSH (19,37,38). The increased levels of GSH in these patients reflect the increased detoxification capacity and resistance in response to the cytotoxic substances released by carcinogen-altered cells (19).…”

The Induction of Prostaglandin E2 Production, Interleukin-6 Production, Cell Cycle Arrest, and Cytotoxicity in Primary Oral Keratinocytes and KB Cancer Cells by Areca Nut Ingredients Is Differentially Regulated by MEK/ERK Activation

“…AN extract induces the differentiation, DNA strand breaks and DNA protein crosslinks in cultured buccal mucosal epithelial cells (19,20). We have demonstrated that AN extract can induce DNA strand breaks and is cytotoxic to oral mucosal fibroblasts (21). AN extract also induces unscheduled DNA synthesis and morphological alterations in cultured gingival keratinocytes (GK) (22).…”

Estimations of various antioxidants in oral cancer patients in comparison with smokers and non-smokers - a biochemical study

“…At least six alkaloids are present in the betel nut itself, of which arecoline and arecadine have been suggested as possible carcinogens. 18 Lipid peroxidation induced by free radicals has been implicated in the pathogenesis of various diseases, and the extent of cellular damage induced by free radicals can be modulated by antioxidant defense mechanisms. 19 The antioxidant property of the serum is attributed to ceruloplasmin.…”