Mechanism of apoptosis of KB cells induced by Topotecan (TPT)

    XU Qiang, WANG Feng, LI Dengª²Song, CHEN Changª²Sheng, XU Wen, MIAO Shan

    1Department of Stomatology, Lanxi Railway Hospital, Lanzhou 730050, 2Department of Nutrition & Food Hygiene, School of Preventive Medicine, Fourth Military Medical University, Xi¬ðan 710033, China, 3Military Medical Institute of Lanzhou Command, 4Department of Statistics, 5Department of Toxicology, School of Preventive Medicine, Fourth Military Medical University, Xi¬ðan 710033, China, 6Institute of Materia Medica, Administration of Scientific Research, Fourth Military Medical University, Xi¬ðan 710033, China

    ¡¾Abstract¡¿ AIM: To study the mechanism of apoptosis of KB cells induced by Topotecan (TPT). METHODS: MTT assay was applied to test the proliferation arrest of KB cells under the treatment of TPT for 12, 24 and 48 h, agarose gel electrophoresis of genomic DNA and flow cytometry (FCM) were used to examine the apoptosis of TPTª²treated KB cells and Westernª²blot was used to test the phosphorylations of p38MAPK proteins. RESULTS: The inhibition ratio of TPTª²treated KB cells for 12, 24 and 48 h was (24.4¡À9.1)%, (33.7¡À6.6)% and (45.1¡À10.4)%, respectively, with significant difference between different treatment duration (P<0.05). By FCM, the apoptosis rate of the cells was (11.5¡À2.8)% at 12h and (31.2¡À4.1)% at 24 h, with significant difference (P<0.01). Agarose gel electrophoresis of genomic DNA of TPTª²treated KB cells for 12 h showed DNA fragmentations, typical index of apoptosis in biochemistry. The phosphorylations of p38 increased gradually with the prolongation of TPT treatment (12, 24 and 48 h) (n=3, P<0.05). CONCLUSION: TPTª²induced apoptosis of KB cells in vitro may result from the enhanced activation of p38MAPK. ......