Arecoline-stimulated placenta growth factor production in gingival epithelial cells: Modulation by curcumin

Abstract

Objective: Placenta growth factor (PlGF) is associated with the progression and prognosis of oral cancer. Materials and methods: This study used ELISA, quantitative polymerase chain reaction, and Western blotting to study the arecoline-stimulated (PlGF) protein or mRNAexpression inhuman gingival epithelial S-G cells. Results: Arecoline, a major areca nut alkaloid and an oral carcinogen, could stimulate PlGF protein synthesis in S-G cells in a dose- and time-dependent manner. The levels of PlGF protein secretion increased about 3.1-and 3.8-fold after 24-h exposure to 0.4 and 0.8 mM arecoline, respectively. Pretreatment with antioxidant N-acetyl-L-cysteine (NAC) and ERK inhibitor PD98059, but not NF-κB inhibitor Bay 11-7082, JNK inhibitor SP600125, p38 MAPK inhibitor SB203580, and PI3-K inhibitor LY294002, significantly reduced arecolineinduced PlGF protein synthesis. ELISA analyses demonstrated that NAC and PD98059 reduced about 43% and 38% of the arecoline-induced PlGF protein secretion, respectively. However, combined treatment with NAC and PD98059 did not show additive effect. Moreover, 10 μM curcumin and 4 mM NAC significantly inhibited arecoline-induced ERK activation. Furthermore, 10 lM curcumin completely blocked arecoline-induced PlGF mRNA expression. CONCLUSION: Arecoline-induced PlGF synthesis is probably mediated by reactive oxygen species/ERK pathways, and curcumin may be an useful agent in controlling oral carcinogenesis. ? 2012 John Wiley & Sons A/S.