Blocking Effect of Gynostemma pentaphyllum Makino (GP) on the Point Mutation of Ha-ras Oncogene during Leukoplakia Canceration

In order to elucidate the blocking effect of Gynostemma pentaphyllum Makino (GP), one of the Chinese medicines, on the point mutation of Ha-ras, oral leukoplakia (OLP) induced by dimethylbenzanthracene (DMBA) in the cheek pouch of Syrian hamster was used. GP was taken in the hamsters with OL. Using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique and tissue specimens indicating OL, the point mutation of Ha-ras oncogene on codon 61 was investigated. The incidences of point mutation were 22.92% in GP-untreated OL and 7.52% in GP-treated OL (6.25% in the glucoside group, 11.00% in the aglucon group and 5.32% in the C20-OH group). GP might prevent the point mutation of Ha-ras oncogene related to OL canceration. This study also suggests that the hydroxyl ion may be the potent component of GP in the inhibition of canceration.