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In Taiwan, the combination of betel quid chewing, alcohol consumption, and smoking habits increases oral cancer risk by 123-fold compared to persons without these habits. Lymphocyte populations in patients may potentially affect the malignant transformation of oral precancer. Methods: A total of 28 patients with oral precancer from our previous cohort were enrolled in this study, and their personal information and oral habits were documented. Their lymphocyte populations (CD4+, CD8+, CD19+, and CD56+) and activation markers (CD25 and CD69) were determined by flow cytometry from 1999 to 2004. After follow up till December 2014, data of patients with/without malignant transformation were recorded, and the relation between oral habits and percentage of initial lymphocyte markers was evaluated using the Student t test and Fisher's exact test. Results: Ten precancer patients developed oral squamous cell carcinoma with a mean period of malignant transformation of 6.8 ± 2.1 years. Patients with malignant transformation had a mean age of 48.4 ± 5.0 years (n = 10), relatively more than that of patients without malignant transformation (41.6 ± 6.3 years, n = 18) (p

AimsChewing of betel quid (BQ) increases the risk of oral cancer and oral submucous fibrosis (OSF), possibly by BQ-induced toxicity and induction of inflammatory response in oral mucosa.MethodsPrimary gingival keratinocytes (GK cells) were exposed to areca nut (AN) components with/without inhibitors. Cytotoxicity was measured by 3-(4,5-dimethyl- thiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. mRNA and protein expression was evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting. PGE2/PGF2α production was measured by enzyme-linked immunosorbent assays.ResultsAreca nut extract (ANE) stimulated PGE2/PGF2α production, and upregulated the expression of cyclooxygenase-2 (COX-2), cytochrome P450 1A1 (CYP1A1) and hemeoxygenase-1 (HO-1), but inhibited expression of keratin 5/14, cyclinB1 and cdc25C in GK cells. ANE also activated epidermal growth factor receptor (EGFR), Src and Ras signaling pathways. ANE-induced COX-2, keratin 5, keratin 14 and cdc25C expression as well as PGE2 production were differentially regulated by α-naphthoflavone (a CYP 1A1/1A2 inhibitor), PD153035 (EGFR inhibitor), pp2 (Src inhibitor), and manumycin A (a Ras inhibitor). ANE-induced PGE2 production was suppressed by piper betle leaf (PBL) extract and hydroxychavicol (two major BQ components), dicoumarol (aNad(p)hQuinone Oxidoreductase--NQO1 inhibitor) and curcumin. ANE-induced cytotoxicity was inhibited by catalase and enhanced by dicoumarol, suggesting that AN components may contribute to the pathogenesis of OSF and oral cancer via induction of aberrant differentiation, cytotoxicity, COX-2 expression, and PGE2/PGF2α production.ConclusionsCYP4501A1, reactive oxygen species (ROS), EGFR, Src and Ras signaling pathways could all play a role in ANE-induced pathogenesis of oral cancer. Addition of PBL into BQ and curcumin consumption could inhibit the ANE-induced inflammatory response.

Betel quid (BQ) chewing is an etiologic factor of oral cancer and submucus fibrosis (OSF). Keratinocyte inflammation is crucial for the pathogenesis of cancer and tissue fibrosis. We found that areca nut (AN) extract (100–400 µg/ml) induced PGE2 production by KB cells by 2.34- to 23.1-fold and also TNF-α production by gingival keratinocytes (GK). Arecoline (0.2–1.2 mM) elevated PGE2 production by KB cells by 2.5- to 6.1-fold. AN extract (200–400 µg/ml) also induced IL-6 production by GK (7.5- to 8.4-fold) and KB cells. In contrast, arecoline (0.1–1.2 mM) suppressed IL-6 production by GK and KB cells, with 42–81 and 41–63% inhibition, respectively. A 48 h exposure of GK to 800–1200 µg/ml AN extract led to 37–69% cell death. Arecoline cytotoxicity to GK was noted at concentrations of 0.8–1.2 mM, which led to 28–38% cell death. AN extract (400–800 µg/ml) induced Cox-2 and IL-6 mRNA expression and also COX-2 protein production by KB cells. IL-6 (5–100 ng/ml) suppressed GK growth by 20–33%, but enhanced oral fibroblast (OMF) and KB cell growth. PGE2 (0.05–5 µg/ml) and anti-IL-6 antibody (ab) (50–1000 ng/ml) showed little effect on GK and KB cell growth. Incubation of GK and KB cells with aspirin, anti-IL-6 ab and anti-TNF-α ab showed little effect on arecoline- and AN-induced cytotoxicity, cell cycle arrest and apoptosis. Exposure to anti-TNF-α ab slightly affected arecoline- and AN-modulated PGE2 and IL-6 production by GK and KB cells. Arecoline- and AN-conditioned medium decreased phytohemagglutinin-mediated CD4+ and CD8+ T cell activation. These results indicate that BQ chewing contributes to the pathogenesis of cancer and OSF by impairing T cell activation and by induction of PGE2, TNF-α and IL-6 production, which affect oral mucosal inflammation and growth of OMF and oral epithelial cells. [ABSTRACT FROM AUTHOR]