Areca nut extract and arecoline induced the cell cycle arrest but not apoptosis of cultured oral KB epithelial cells: association of glutathione, reactive oxygen species and mitochondrial membrane potential
Mc. Chang et al., Areca nut extract and arecoline induced the cell cycle arrest but not apoptosis of cultured oral KB epithelial cells: association of glutathione, reactive oxygen species and mitochondrial membrane potential, CARCINOGENE, 22(9), 2001, pp. 1527-1535
There are 600 Million betel quid (BQ) chewers in the world. BQ chewing is a
major etiologic factor of oral cancer. Areca nut (AN) and arecoline may in
hibit the growth of oral mucosal fibroblasts (OMF) and keratinocytes. In th
is study, AN extract (100-800 mug/ml) and arecoline (20-120 muM) inhibited
the growth of oral KB cells by 36-90 and 15-75%, respectively. Exposure to
arecoline (>0.2 mM) for 24 h induced G(2)/M cell cycle arrest of OMF and KB
cells. Areca nut extract (>400 mug/ml) also induced G2/M arrest of KB cell
s, being preceded by S-phase arrest at 7-h of exposure. No evident sub-G(0)
/G(1) peak was noted. Marked retraction and intracellular vacuoles formatio
n of OMF and KB cells were observed. Glutathione (GSH) level, mitochondrial
membrane potential (Delta betam) and H2O2 production of KB cells were meas
ured by flow cytometry. GSH level [indicated by 5-choromethyl-fluorescein (
CMF) fluorescence] was depleted by 24-h exposure of KB cells to arecoline (
0.4-1.2 mM) and AN extract (800-1200 mug/ml), with increasing the percentag
e of cells in low CMF fluorescence. By contrast, arecoline (0.1-1.2 mM) and
AN extract (800-1200 mug/ml) induced decreasing and increasing H2O2 produc
tion (by 2',7'-dichlorofluorescein fluorescence), respectively. Hyperpolari
zation of Apm (increasing of rhodamine uptake) was noted by 24-h exposure o
f KB cells to arecoline (0.4-1.2 m-M) and AN extract (800-1200 mug/ml). AN
extract (100-1200 mug/ml) and arecoline (0.1-1.2 mM) induced little DNA fra
gmentation on KB cells within 24 h. These results indicate that AN ingredie
nts are crucial in the pathogenesis of oral submucous fibrosis (OSF) and or
al cancer by differentially inducing the dysregulation of cell cycle contro
l, Delta betam, GSH level and intracellular H2O2 production, these events b
eing not coupled with cellular apoptosis.