The comparative study of inhibitory effects of 99Tc-methylenediphosphonate and 153Sm-ethylene diamine tetramethylene phosphonic acid on bone invasion and osteolysis

Objective: To observe the inhibitory effects of 99Tc-methylenediphosphonate (99Tc-MDP) and 153Sm-ethylene diamine tetramethylene phosphonic acid (153Sm-EDTMP) on bone invasion and osteolysis by Walker 256 carcinoma in rats, and their influence on the implanted tumor cells comparatively. Methods: Bone invasion and osteolysis model was induced by Walker 256 carcinoma cells. The animals were divided into four groups: control group, 99Tc-MDP treatment group, 153Sm-EDTMP treatment group and 99Tc-MDP+ 153Sm-EDTMP treatment group. Radionuclide bone scan of 99Tcm-MDP, X-ray and histological examination were used in the experiment to estimate the inhibitmy effects of 99Tc-MDP or/and 153Sm-EDTMP on the bone invasion and osteolysis. Meanwhile, the rate of apoptosis and percentage of each cell cycle phase of the rat-implanted tumor were analyzed by flow cytometry. Results: Compared with the control, the rat number of tibia invasion and bone absorption reduced markedly in 99Tc-MDP treatment group, 153Sm-EDTMP treatment group and 99Tc-MDP+153Sm-EDTMP treatment group(Fisher's exact test: P<0.05). The rat number of bone absorption in the 99Tc-MDP+153Sm-EDTMP treatment group was lower than that of 99Tc-MDP treatment group and 153Sm-EDTMP treatment group. However, there was no significant difference. In addition, the rate of cell apoptosis in all the treatment groups was greater than that of the control group. And the cell percentage of DNA synthesis phase(S phase) notably dropped. There was enhancive effect on the transplanted tumor cells when both 99Tc-MDP and 153Sm-EDTMP were injected into the Walker 256 bearing rats. Conclusions: (1) 99Tc-MDP and 153Sm-EDTMP can obviously prevent bone invasion and osteolysis induced by Walker 256 carcinoma in rats. (2)They also have an effect on inducing the apoptosis of implanted tumor cells and inhibiting the proliferation of the transplanted tumor cells. There is enhancive effect on the implanted tumor cells when 99Tc-MDP and 153Sm-EDTMP are applied simultaneously. (authors)