The Inhibitory Effect Of ～(99)Tc-MDP And ～(153)Sm-EDTMP On Bone Invasion And Osteolysis Induced By Walker 256 Carcinoma In Rat

Objective: Bone invasion and osteolysis rat model used in our experiment, was induced by Walker 256 carcinoma. Radionuclide bone scan, X-ray and histopathologic examination were used to estimate the inhibitory effect of ⁹⁹Tc-MDP and ¹⁵³Srn-EDTMP on the bone invasion and osteolysis separately or associately, whether they had influence on the implanted tumor was also analyzed by flow cytometry (FCM). It would have important theoretic and realistic significance in solving the problem of bone metastatic therapy.Methods: Female Wistar 40 rats, weighing 240 to 260g, about 2 ml (4X10⁶ tumor cells) of the malignant ascitic fluid was injected into the adjacent gastrocnemius muscles of the right hind leg tibias. All the tumor-induced rats were divided into A, B, C and D four groups randomly. Group A, B, C and D referred to the control group (the non-treated group); the ⁹⁹Tc-MDP treated group (Rats were given ⁹⁹Tc-MDP injection at a dose of 3 mg·kg^-1·d^-1 into the caudal vein of the rats from the fifth day to the fourteenth day after the implantation); ¹⁵³Srn-EDTMP treated group (¹⁵³Srn-EDTMP at a dose of 37MBq/kg was injected once on the fifth day); and ⁹⁹Tc-MDP+153Srn-EDTMP associated treated group (Rats were given 99Tc-MDP injection at a dose of 3 mgkg'-d"1 from the fifth day after implantation until the fourteenth day and l53Sm-EDTMP at a dose of 37MBq/kg was injected once on the fifth day) respectively. On the fifteenth day after the implantation, the whole body bone imaging of the four groups was acquired, and the radioactive count ratio of tumor-implanted side tibia to the counterlateral side tibia was calculated. Meanwhile, X-rays of the hind limbs of tumor-induced rats were taken. Then, all the rats were killed. The rat body, the implanted-tumor and the two side tibias were weighed up after the rats were dissected. In addition, histopathologic analysis of the both side tibias was carried out. The two tibias were cut transversely and examined with hematoxylin and eosin (H and E) staining. In addition, the apoptosis rate and the cell percentage of each cycle phase of Walker 256 carcinoma cells were also analyzed by flow cytometry (FCM) to estimate the influence of 99Tc-MDP and 153Sm-EDTMP separately or associately on the implanted tumor. All the quantitative data were analyzed by t test and analysis of variance (ANOVA) from SAS statistical software. Fisher's extract test was used in count data.Results: (1) Whole body bone imaging Radioactive distribution of tumor-implanted side tibia was higher than that of the opposite side in the four groups, but the difference was not statistically significant (P>0.05). (2) X-rays 60% of rats in Group A had slight bone destruction and periosteum response.But in the other groups, no bone destruction was seen, the percentage of periosteum response was 30%, 40% and 20% respectively, which were lessened in a certain degree compared with Group A. (3) The histological examination There was no abnormity in the counterlateral tibia under the light microscopy. On the contrary, prevailing or local bone absorption, marrow cell putrescence, ossification and fibrosis of the implanted-tumor tibia were acquired in all the rats of Group A, but in the treated groups, the number fell remarkably, there was statistical significance compared with non- treated group, however, the difference was not statistically significant between Group D and Group B or Group C, though the number of tibia lesions in Group D was lower than that of Group B and Group C. Meanwhile, in Group B, C and D, periosteum response and the number of osteoclasts had lessened to various extent. (4) The rate of apoptosis and the cell percentage of each cycle phase of Walker 256 carcinoma cells The apoptosis rate of Walker 256 carcinoma cells in Group B, C and D was greater than that of Group A, the statistical analysis showed a highly significant difference (PO.05), and a more favorable effect, that is, the apoptosis rate of Walker 256 carcinoma cells in Group D was greatly higher than Group B and C (P<0.05). There was no statistically different between Group B and C (P>0.05). Meanwhile, in the treated groups, the cell percentage of resting phase and DNA presynthetic phase (Go/Gi phase) was greatly higher and the cell percentage of DNA synthesis phase (S phase)was notably lower when compared with the Group A. However, in the four groups, the cell percentage of prophase of cell division and cell division phase (G2/M phase) hadn't changed greatly. (5) The body weight and the implanted-tumor weight in the four groups were analyzed by SAS software, there was no statistical significance (P>0.05).Conclusions: (1) 99Tc-MDP and 153Srn-EDTMP could obviously inhibit the activity of the osteoclasts, prevent the tumor-induced bone from invasion and osteolysis, and also could control adjacent periosteum response. There was not significant difference between the only "Tc-MDP treated group and only 153Sm-EDTMP treated group, there was a satisfactory effect when combined 99Tc-MDP with l53Srn-EDTMP.(2) Both 99Tc-MDP and 153Sm-EDTMP could induce apoptosis of walker 256 carcinoma cells and can inhibit the proliferation of the Walker 256 carcinoma cells and the effect was carried out by DNA synthesis phase (S phase). 99Tc-MDP+l53Sm-EDTMP associated treatments in the influence of the implanted tumor was superior to only 99Tc-MDP treatment or 153Sm-EDTMP treatment. (3) The experiment showed that the liver of tumor-bearing rats in Group B and D had absorbed much 99Tc-MDP, which probably had connected with the way of iv. The mechanism of "Tc-MDP absorption of the liver and the connection between "Tc-MDP absorption and the way of iv. need further study to confirm.(4) The accuracy of the whole body bone imaging was higher than that of X-ray picture, and...