ABSTRACT
Objective To study the effects of internal exposure of 18F-FDG (18F-2-deoxy-2-fiuoroD-glucose) on the protein expressions of P53,XIAP (X-linked inhibitors of apoptosis protein) and GADD (growth arrest and DNA damage)45 in Lewis lung carcinoma,and to explore the possibility of applying 18F-FDG as a radiotherapy drug in vivo.Methods Lewis lung cancer transplanted tumor models were established via subcutaneous injection of 0.2 ml of 2 × 107/ml Lewis lung carcinoma cells at left hind limbs of 48 C57BL/6 mice that were randomly divided into high dose group,low dose group and control group with 16 mice each.After 7 d of cancer cell inoculation,18.5 × 107 Bq and 9.25 × 107 Bq of 18F-FDG in 0.2 ml saline or equal volume of physiological saline was intraperitoneally injected into three group mice,respectively.22 d post inoculation,the protein expressions of P53,XIAP and GADD45 were immuohistochemically detected by using SP approach.Results There was significant difference among the protein expressions in each group (x2 =8.30,16.02,7.68,P ＜0.05).The mean integral optic density of protein expression increased from 0.089 ± 0.033 in control group to 0.315 ± 0.028 in high dose group for P53,and from 0.126 ± 0.023 to 0.383 ±-0.035 for GADD45,but it decreased from 0.422 ± 0.034 to 0.149 ± 0.055 for XIAP.There was significantly difference of these protein expressions in each group (P53:F=5.26,P＜0.05;XIAP:F=4.29,P ＜0.05;GADD45:F=5.98,P ＜0.05).Conclusions 18F-FDG can up-regulate the expressions of P53 and GADD45 proteins and down-regulate the expression of XIAP protein in tumor cells,and it inhibits tumor growth by promoting cell apoptosis in the Lewis lung carcinoma tissue with a P53-dependent manner.
ABSTRACT
Objective To investigate the influence of 18F-FDG on the proliferation of Lewis lung cancer cell line,and to elucidate its possible mechanism.Methods Morphological changes of cells after culture for 24 h at different concentrations of 0,0.37,1.85,3.70 and 7.4 (×106) Bq/ml of 18F-FDG were observed by using inverted microscopy and electron microscopy.The apoptosis and phase distribution of cell cycle of irradiated cells were analyzed with flow cytometry.DNA synthesis of irradiated cells was assayed by 3H-TdR incorporation.Lipid peroxidation was measured by chromometry and expression of Bcl-2 and Bax protein was measured by immunohistochemical technique.Results Exposed to (0-7.40) × 106Bq/ml of 18F-FDG for 24 h,the cumulative absorbed doses delivered to cells in five groups were 0,0.11,0.55,1.10 and 2.20 Gy,respectively.Irradiated cells showed morphological changes of apoptosis.The apoptosis rate of irradiated cells was increased from (4.05 ± 0.01)% to (25.6 ± 0.28) % (t = 188,P＜0.01).3H-TdR incorporation rate was decreased from 100% to(22.0 ± 0.51)% (t =27.6,P ＜0.05).The levels of M DA in cells were augmented from (0.08 ± 0.03) to (0.67 ± 0.12) μmol/L (t =11.7,P ＜ 0.01).Cell cycle arrest was found in G2/M phase with the increasing doses from 0 to 2.20 Gy.The expression of Bcl-2 protein was decreased while that of Bax protein increased.Conclusions 18F-FDG could induce the apoptosis of cells and inhibit the proliferation of cells.