The Expression Of The SPATA5L1, Cyclin B2 In The Formation Of Multinuclear Giant Cells Induced By Irradiation And Paclitaxel

Background and objection: The G2 / M arrest of human oral epidermis carcinoma KB cells could be induced by the synergic effect of ionizing radiation with paclitaxel. Earlier biochip screening analysis found that ten genes related to regulate cell division have differently expressed after treated with ionizing radiation and/or paclitaxel.This study was to investigate the potential molecular mechanism by quantitative assessment of two genes expression levels among the ten genes. The SPATA5L1 gene espression was quantified by real-time quantitative PCR. And the protein expressed levels of SPATA5L1 and Cyclin B2 were detected by Western Blot.Method: The KB cells were exposed to 60Coγ-Ray and paclitaxel with different dose and concentration, and then (1) the morphology of KB cells was observed through microscopy, the cell proliferation inhibition was detected by clone forming test, (2) the gene expression level of SPATA5L1 was tested by real-time quantitative PCR, (3) the expressed protein levels of SPATA5L1 and Cyclin B2 were detected by Western Blot.Results: (1) The proliferation of KB cell line has been inhibited significantly by the synergic effect of ionizing radiation with paclitaxel, and the effect was radiation dose and concentration dependent. (2) The multinuclear giant cell has been found after treated by ionizing radiation and paclitaxel, which finally died. (3) From the results of real-time quantitative PCR, the expression of SPATA5L1 gene was increased in the KB cell treated by different dose ionizing radiation or ionizing radiation cooperated with 40 nmol/L paclitaxel. (4) The expressed protein level of SPATA5L1 was increased after treated with different dose ionizing radiation or ionizing radiation cooperated with 40 nmol/L paclitaxel (below 6Gy), however, the expressed protein level of Cyclin B2 was decreased at the same time.Conclusion: The multinuclear giant cell formation was one of the main reasons for KB cell proliferation inhibition induced by the synergic effect of ionizing radiation with paclitaxel. The possible molecular mechanism was that high level expression of SPATA5L1 and the down-regulated expression of Cyclin B2. The down-regulated expression of Cyclin B2 may result in the inhibition of mitotic spindle formation, meanwhile, the high level expression of SPATA5L1 may interfere with the function of contractile ring. The cytoplasm split to form new daughter cells was blocked after nucleolus division in the process of cell division, as the result of, many multinuclear giant cells had been formed, and finally died.