Effects and possible mechanism of valdecoxib on apoptosis of cancer in nude mice / 中国药理学通报

ABSTRACT

Aim To investigate the effects and possible mechanism of valdecoxib on apoptosis of cancer in nude mice.Methods The tumor model was established by inoculating 2?106 cell both in the left and right armpit respectively.The mice were divided randomly into control group and valdecoxib group(20 mg?kg-1?day-1).Valdecoxib was dissolved in carboxymethylcellulose sodium and administered from the second day after inoculation.The mice were killed after 4 weeks.The volumn and inhibitory rate were calculated according to the length and width of xenograft tumor.H.E staining was used to observe the cell structure of the stomach and colon.The apoptotic rate was detected by FCM.The expression of COX-2,c-jun and c-fos protein was detected by FCM and immunohistochemical staining.Total RNA was extracted with Trizol method and the expression of COX-2 mRNA was detected by RT-PCR.Results(1) The body weight of nude mice was higher in valdecoxib treated group in a time-dependent manner.(2) Valdecoxib inhibited the growth of tumor.The weight of tumor was decreased from(1.43?0.52)g in control group to(0.93?0.53)g in valdecoxib treated group.The ratio of inhibition on the growth of tumor was 45.80%.(3) Valdecoxib increased the apoptosis rate from(14.15?0.48)% in control group to(29.80?6.35)% in treated group.(4) The expression of COX-2 mRNA and protein decreased in treated group compared with that in control group.FCM and immunohistochemical staining showed that the expressions of c-jun and c-fos were increased in valdecoxib treated group.There was statistical significance compared with control group.(5) There was significantly negative correlation between the ratio of apoptosis and the expression of COX-2(r=-0.726,P=0.008);there was significantly positive correlation between the ratio of apoptosis and the expressions of c-jun and c-fos protein respectively(r=0.603,0.813;P=0.038,0.001);(6) Valdecoxib did not affect cell structure of stomach and colon.Conclusions valdecoxib inhibits the growth of the xenograft tumor in nude mice and induces the apoptosis.Decreasing expression of COX-2 and up-regulating the expressions of c-jun and c-fos may be one of the mechanisms for the apoptosis.