Apoptosis of Human Nasopharyngeal Carcinoma CNE-2Z Cells Induced by Tubeimoside Ⅰ
Weng Xi Yang, Ma Run Di, Yu Li Jian Guangdong Provincial Key Laboratory of Marine Materia Medica,Zhanjiang Ocean University,Zhanjiang, Guangdong,524025,P.R.China
BACKGROUND OBJECTIVE: Tubeimu,Bolbostemma pani culatum(Maxim.) Franquet (Cucurbitaceae),is a kind of traditional Chinese medicinal herb. Our previous studies revealed that tubeimosideⅠ, a triterpenoid saponin isolated from the tubers of Bolbostemma paniculatum, showed potent antitumor effect. This study was designed to investigate the effect of tubeimoside Ⅰon the apoptosis of human nasopharyngeal carcinoma cell line CNE 2Z. METHODS: Cell growth inhibition mediated by tubeimosideⅠwas measured by MTT assay after treatment with tubeimosideⅠ. The effect of tubeimoside Ⅰon apoptotic induction in CNE 2Z cells was determined using the fluorescent microscopy,electronic microscopy,DNA agarose gel electrophoresis,and flow cytometry,respectively.Western blot analysis was performed to detect the changes of apoptosis related genes bcl 2 and bax protein expression. RESULTS: TubeimosideⅠdisplayed growth inhibitory activity against CNE 2Z cells with IC50 values of 32 5, 20 7, and 16 7 μmol/L for 24, 48, and 72 hours, and CNE 2Z cells showed typical apoptotic morphological features observed by fluorescent microscopy and electronic microscopy.In CNE 2Z cells occurred typical "Ladder"bands after being exposed to tubeimosideⅠ(10 μmol/L, 24, 48, 72 hours; 30, 40, 50, 60 μmol/L, 12 hours). Sub G1 peak was found using flow cytometry. When CNE 2Z cells were exposed to tubeimosideⅠ(50 μmol/L, 12 hours), the apoptosis index was 72 8%. The down regulation and phosphorylation of bcl 2 (an inhibitor of apoptosis) were detected at 1 hour after the addition of tubeimoside Ⅰ. In contrast, the levels of bax appeared to be significantly upregulated at 1, 3, 5, and 24 hours after the addition of tubeimosideⅠ. CONCLUSION: TubeimosideⅠcan induce the apoptosis of CNE 2Z cells, and the induction of apoptosis by tubeimosideⅠis closely associated with downregulation and phosphorylation of bcl 2 and bax activation.
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