Chromosomal Instability Changes In MAD2/BUB1-knockout Human Osteosarcoma Cells After Simulated Microgravity

Chromosomal instability manifested as altering in chromosome number andstructure. Our group previous study showed that cell cycle was blocked in G2/Mphase, BUB1and MAD2were both overexpressed with the incidence of abnormalmultipolar spindle increased in human osteosarcoma cell lines (U-2OS) afterground-based simulated microgravity effect. For further study of molecularmechanism of chromosomal instability in U-2OS under sustaining simulatedmicrogravity environment. Firstly, two recombinant had been constructed whichincluded BUB1siRNA via RNA interference technology. Additionally, pSilencer4.1-siRNA control, pSilencer4.1-BUB1siRNA and pSilencer4.1-BUB1siRNAwhich had been constructed by group preliminary study were transfected into theU-2OS cells. Then the cells were selected by G418and a number of clones wereacquired for the follow study. Finally, the incidence of abnormal multipolar spindle,cell cycle and DNA content of BUB1/MAD2RNAi U-2OS cells which had beencultured under sustaining simulated microgravity environment were analyzed.The result showed that the incidence of abnormal multipolar spindle increasedin U-2OS cells of siRNA control group but dropped in U-2OS cells ofBUB1/MAD2RNAi group after ground-based simulated microgravity effect andcell cycle were arrested at G2/M phase both in siRNA control group andBUB1/MAD2RNAi group at the same time. But, the effect of this block decreasedwith the prolongation of the time of simulated microgravity in U-2OS cells whichBUB1/MAD2had been RNAi. Additional, the DNA content was changed more andmore obviously in U-2OS cells of BUB1/MAD2RNAi group as the time that cellscultured in sustaining simulated microgravity environment going on. These resultssuggest that chromosomal instability enhanced in U-2OS cells which BUB1/MAD2had been silenced after ground-based simulated microgravity effect. The abovefindings laid a certain foundation for further explore to the molecular mechanism ofchromosomal instability under simulated microgravity environment.