Study On The Killing Mechanism Of Chlorine Dioxide To MCF-7 Cells And Its Effect On The Growth Of Transplanted Tumor In Nude Mice

Objectives:Study on the killing activity and its mechanism of chlorine dioxide(ClO2)on MCF-7 cells.And on this basis,the effects of ClO2 on the growth of transplanted tumors in nude mice were investigated.Methods:1.Breast cancer MCF-7 cell lines were divided into two groups based on the research object: the control group and the ClO2 intervention group.MTT assays were used to detect the cell viability,growth curve and dose-effect relationship of breast cancer MCF-7 cells after ClO2 intervention.2.The changes of cell cycle,apoptosis and cell membrane permeability of MCF-7 cells were detected by flow cytometry(FCM).3.Morphological integrity of MCF-7 cells was observed by HE stain.Giemsa staining was used to observe the changes of chromosome structure.4.The model of transplanted tumor(MCF-7 cells)in nude mice was constructed.And then,ClO2 was injected into the transplanted tumor to observe the changes of the diameter of the tumor.Treated for a certain time,the transplanted tumor was taken and used for paraffin sections.HE staining and immunohistochemuical staining(Ki67 and VEGF)were performed on slices.Results:1.The proliferation of MCF-7 cells was significantly decreased compared with the control group(P < 0.05).The proliferation rate was inversely proportional to the drug concentration.The effective inhibitory concentration of ClO2 was 13 μg / mL and the effective killing concentration was 26 μg / mL.2.FCM results showed that the ClO2–treated MCF-7 cells cycle were arrested in the G1 phase,and the cell growth of MCF-7 was inhibited(P < 0.05).ClO2 had a significant effect on the apoptosis of breast cancer cells(P < 0.05).The early apoptotic MCF-7 cells decreased and the advanced apoptotic MCF-7 cells increased with the increasing of ClO2 concentration.3.The results of PI staining indicated that the permeability of MCF-7 cells membrane was increased with the increasing of ClO2 concentration.4.The results of HE stain and Giemsa staining revealed that the cell membrane integrity and the chromosome structure damage gradually increased with the increasing of ClO2 concentration.The number of nucleole increased gradually,while the morphological of the nuclei was changed a little.5.Extensive necrosis occurred within the tumor after injection of ClO2 in the transplanted tumor.HE stain and immunohistochemical staining(Ki67 and VEGF)showed that only the edge of the tumor was partially positive staining.Conclusions:1.The growths of MCF-7 cells were inhibited on MCF-7 cells after treating with ClO2.And the cell viability was inversely proportional to the ClO2 concentration.2.Cell proliferation was mainly affected by low concentration of ClO2.Apoptosis was mainly induced by medium concentration of ClO2.Cell necrosis was mainly caused by higher concentration of ClO2.3.Transplanted tumor internal necrosis occurred after treating with high ClO2 concentration.And the damage to the skin in the injection area was controllable.Thus,the idea of ―treating superficial tumors as trauma‖ is feasible.