Reversion Of Drug Resistance In Osteosarcoma Cell Induced By Caffeine

[Objective] To observe whether there is G2M arrest in osteosarcoma cells with drug resistance when they are treated with usually used chemotheropeutic drugs ,whether caffeine can shorten or cancel G2M arrest and reverse the drug resistance in osteosarcoma cells in vitro .[Method] A multi-drug resistant cell model R-OS-732 was established by incubation of small dosage of DOX from native osteosarcoma cell line OS-732 .The cell inhibition ratios of different concentration grade of DOX and MTX to the two kinds of cells were measured with the MTT colorimetric analysis. lC50 of DOX and MTX to the two kinds of cells was then calculated with the statistic software SPSS 12.0. According to the principle of factorial experiment ,the drug resistant cells R-OS-732 were divided into six groups and treated with no drug ,DOX, MTX, Caffeine, DOX and Caffeine ,MTX and Caffeine, respectively, and cultured in 37℃ 5%CO2 incubator . The ratios of cells on G2M phase of each group were measured with flow cytometry after 48 hours incubation and the cell inhibition ratios were measured with the MTT colorimetric analysis after 72 hours incubation. The results were analyzed to discover the change of G2M and cell inhibition ratio after using caffeine .[Result] The IC50of DOX to R-OS-732 is 4.58 times that to OS-732, The IC50of MTX to R-OS-732 is 3.75 times that to OS-732, which testified the success of establishing a multidrug resistant osteosarcoma cell model. The ratios of cells on G2M phase were significantly increased after being treated with DOX or MTX only, were not increased after adding caffeine to DOX or MTX, and were not changed after being treated with caffeine only. Namely, there was G2M arrest in multidrug-resistant osteosarcoma cells after being treated with DOX or MTX only, which could be canceled or shortened by caffeine. There was no effect on G2M phase of caffeine using only. At the same time , the cell inhibition3ratios were significantly increased after adding Caffeine to DOX or MTX, and no effect of caffeine on the cell inhibition ratios was detected .There was interaction between Caffeine and DOX ,Caffeine and MTT.[Conclusion] 1 There is G2M arrest in the multidrug resistant osteosarcoma cells when being treated with DOX or MTX,which may be one of the mechanisms of multiple drugresistance.2 Caffeine can shorten or cancel G2M arrest ,so it can shorten the repairing time of the cells with DNA damage.3 There is interaction between Caffeine and DOX ,Caffeine and MTT , which can increase the cell inhibition ratio and reverse the multidrug resistance.