Experimental Study Of The Radiosensitization Of Curcumin To The Human Osteosarcoma Cell Line

Osteosarcoma is a kind of malignant tumor originate from mesenchymal tissue, which onset mostly in children and adolescent. Because of its high malignant and strong invasiveness, the pulmonary metastasis of osteosarcoma is early and the prognosis is poor. With the application of neoadjuvant chemotherapy in recent years, the survival rate of osteosarcoma has improved remarkably. However, considering some special patients which the tumor occurrs in vertebral column, base of skull, pelvis and the recurred patients after amputation, operation is not suitable for them and have to take advantage of high doses chemotherapy for palliative therapy, but the effect is poor. Considering the low radiosensitivity, if there is way to enhance the radiosensitivity of osteosarcoma, the status would be improved with the advantage of radiotherapy.The radiosensitizer study in oncology research has important significance for improving the efficacy of clinical radiotherapy. It's reported that the celluar radiosensitivity is closed related to the DNA self-repairing mechanism which ATM play important role in. It's also reperted that some drugs achieve the role radiosensitizing effect through decrease the ATM expression. In our study, we used the U-2OS cell line as model to investigate how curcumin radiosensitized through DNA repair mechanisms. Chapter one:Curcumin combined X-ray affects the cell growth and cell cycle of U-2OSObjectiveTo investigate the effect of curcumin combined X-ray on inhibition of proliferation and arrest of cell cycle in U-2OS cell. To investigate the effect of curcumin acting as a kind of radiosensitizer.MethodsThe U-2OS cell was divided to four groups randomly:control group; curcumin group; X-ray group; curcumin+X-ray group. Cell growth suppression of each group was analyzed by MTT assay and clony forming assay. The cell cycle and apoptosis of each group were also detected by flow cytometry.ResultsThe proliferation of U-2OS cells were inhibited remarkably in curcumin+X-ray group, The higher the concentration the stronger the inhibition. We also noticed that the SF of the curcumin+X-ray group is lower than the control group. It also resulted in S phase arrest.ConclusionIt suggested that curcumin can radiosensitized the U-2OS cell line, and S phase arrest may be one of the mechanism. Chapter two:Inhibition of the ATM expression caused by curcumin could enhance the radiosensitivity of U-2OS cellObjectiveTo investigate the curcumin whether could affect DNA damage repair capacity after the radiation treatment through targeted inhibition of human osteosarcoma U-2OS cells'ATM gene expression.MethodsTo analysis the ATM expression of U-2OS through Real-time PCR and Western Blot after RNA interfere. The U-2OS cell was divided to four groups randomly:NCsiRNA group; NCsiRNA+X-ray group; ATMsiRNA group; ATMsiRNA+X-ray group. Cell growth suppression of each group was analyzed by MTT assay, Cell cycle was detected by flow cytometry. Besides, we analysed the relation between curcumin and ATM.ResultsWe noticed that the SF of the curcumin+X-ray group is lower than the NCsiRNA group. We also noticed the S phase arrest in ATMsiRNA+X-ray group. The depressed expression of ATM treated by curcumin was detected through Real-time PCR and Western Blot. ConclusionThe U-2OS display high radiosensitivity after the ATM gene was silenced. Meanwhile, curcumin was able to inhibite the expression of ATM. Chapter three:Inhibition of the ATM expression caused by curcumin is interfered by the NF-κBObjectiveTo investigate the curcumin whether could affect DNA damage repair capacity after the radiation treatment through targeted inhibition of human osteosarcoma U-2OS cells'NF-κB expression.MethodsTo analysis the NF-κB expression of U-2OS through Real-time PCR and Western Blot after RNA interfere. The U-2OS cell was divided to four groups randomly:NCsiRNA group; NCsiRNA+curcumin group; NF-KBsiRNA group; NF-κBsiRNA+curcumin group. To investigate the ATM expression caused by X-ray after NF-KBsiRNA transfect through Real-time PCR and Western Blot.ResultsThe depressed expression of ATM treated by curcumin was detected through Real-time PCR and Western Blot, but the NF-κBsiRNA+curcumin group was not significant.ConclusionCurcumin inhibited the ATM gene expression through NF-κB signal transduction pathways and reduced DNA damage repair capacity, so as to achieve a radiosensitizing effect.