Preliminary Study On The Effects Of Vitamin D On Mechanisms Of Bone Metastasis In Breast Cancer

ObjectiveBreast cancer is one kind of common malignant tumor in woman.The bone is one of the most common sites of metastases in breast cancer. Recent researchs found that vitamin D is not only reduce the risk of morbidity rate, recurrence rate and mortality rate in breast cancer,it also has certain relation with bone metastases. In the experiment,we observed the effects of vitamin D3and1,25(OH)2D3on the proliferation of the human breast cancer cell lines (MDA-MB-231, T47D) and the human osteoblast like cell lines (MG-63),and detected the changes of the related cytokines influenced by above drugs. Through these ways,we can study the effects of vitamin D on mechanisms of bone metastasis in breast cancer,and provide new ideas for the treatment of breast cancer.MethodsThe human breast cancer cell lines (MDA-MB-231,T47D) and human osteoblast like cell lines (MG-63) were cultured respectively. Then we collected supernatant from above cells when they are in logarithmic growth phase. Meantime,vitamin D3and1,25(OH)2D3were diluted in optimal concentration (vitamin D3was diluted in10-3mol/L,10-4mol/L,10-5mol/L,10-6mol/L,10-7mol/L,10-8mol/L;1,25(OH)2D3was diluted in10-7mol/L,10-8mol/L,10-9mol/L,10-10mol/L) for the experiment. The proliferation of human breast cancer cells and human osteoblast like cells influenced by vitamin D3and1,25(OH)2D3was measured by CCK-8assay.The migration rate of above cells influenced by vitamin D3and1,25(OH)2D3was measured by migration assay. The generation of OPG and sRANKL influenced by vitamin D and conditioned medium from two types of human breast cancer lines were measured by enzyme-linked immuno sorbent assay (ELISA).and the generation of PTHrP influenced by vitamin D3and1,25(OH)2D3were also measured by ELISA.Results1. The results of cell proliferation and migration(1) The vitamin D3inhibited the migration and proliferation of breast cancer cell lines (MDA-MB-231,T47D)and display a dose-dependent effect. There were different effects with different concentrations of vitamin D3on MG-63cells, showing that the high concentration groups inhibit the proliferation and migration of MG-63cells, while the low concentration groups promoting.(2) The1,25(OH)2D3inhibited the migration and proliferation of MDA-MB-231cells,T47D cells and MG-63cells. There were a dose-dependent effect.(3) The supernatant from breast cancer cells promoted the proliferation of themselves with a dose-dependent effect.2.The changes of OPG, sRANKL(1) The vitamin D3inhibited the generation of OPG and had different effects on generation of sRANKL with different concentrations.The high concentration groups promoted the produce of sRANKL,and the low concentration groups inhibited its produce of sRANKL.(2)Thel,25(OH)2D3inhibited the generation of OPG and promoted the produce of sRANKL.The effect of1,25(OH)2D3is better than vitamin D3in the same Concentration group.(3) The supernatant from MDA-MB-231/T47D cells inhibited the generation of OPG and promoted the produce of sRANKL.3.The vitamin D3and1,25(OH)2D3inhibited the generation of PTHrP.The inhibitory effect is more apparent with the concentration increased.Conclusion1. The supernatant from breast cancer cells promoted the proliferation of themselves.It suggests that breast cancer cells would influence the growth of themselves by secreting some factors.2. Vitamin D can affect the proliferation of breast cancer cells and human osteoblast like cell lines,inhibit the generation of PTHrP from breast cancer cells and influences the formation of OPG and sRANKL. The effect of1,25(OH)2D3is better than vitamin D3in the same Concentration group.It means that vitamin D may improve the prognosis of breast cancer patients through inhibiting the proliferation of breast cancer cells and influencing bone microenvironment.