Study On The Proliferation And Apoptosis Of Normal Mammary Epithelial Cells And Cancer Cells Induced By Cadmium

The mammary gland is the most important skin derivative of human and animal,and it is also the only secretory gland that feeds the milk of the young.The normal growth and development of the mammary gland directly determines the lactation ability of the animal(cow),and the changes of genetic and environmental factors can promote the abnormal proliferation of mammary gland tissue,leading to the occurrence and metastasis of breast cancer.Environmental pollutant heavy metal cadmium is gradually deposited in animals through bioaccumulation and induces the occurrence of cancer,such as skin cancer,bladder cancer,breast cancer,oral cancer,etc.The carcinogenic mechanisms mainly include inflammatory response,oxidative stress,apoptosis attenuation,DNA damage,gene mutation,and abnormal cell proliferation.At present,although studies have shown that heavy metal cadmium can induce abnormal growth of mammary epithelial cells,and Shh signaling pathway-related proteins are involved in regulating epithelial cell proliferation,the specific molecular mechanism is still unclear.However,the intervention of environmental pollutant heavy metal cadmium on the growth of dairy cow mammary gland directly leads to the reduction of milk yield and production efficiency,and the proliferation and metastasis of cancer cells induced by cadmium are the main factors that are difficult to cure clinical breast cancer.Therefore,this paper explores the effect of cadmium on normal mammary epithelial cells and breast cancer cells through in vitro and in vivo experiments,which not only provides important guidance for improving the efficiency of milk production of dairy cows,but also has extremely high reference significance for the study of molecular mechanism of breast cancer proliferation and metastasis in humans and animals.1 Study on the proliferation and apoptosis of normal mammary epithelial cells induced by cadmiumThis subject firstly investigated whether cadmium can activate the Shh signaling pathway.Normal bovine mammary epithelial cells BMEC and human mammary epithelial cells MCF10A were selected for cadmium chloride treatment.The results of Western Blot experiments showed that the expression of Glil increased with the concentration and time,indicating that the Shh signaling pathway was activated,while downstream stem cell related proteins BMI1 and SOX2 decreased.To further verify the effect of cadmium on stem cell-related proteins,the ALDEFLOUR experiment found that the content of stem cell marker ALDH was also reduced,which was consistent with WB.This experiment further tested the effect of cadmium on the viability,proliferation and migration,tumorigenicity and apoptosis of mammary epithelial cells.The results showed that cadmium could reduce cell viability and migration,and significantly inhibit the number of microspheres.The proportion of G0 phase cells decreased,while that of S phase cells increased,prolonging the physiological cycle of cells.At the same time,cadmium exposure significantly promoted the cleavage levels of Caspase-8,Casepase-3 and PARP,and the results of flow cytometry showed that the apoptosis rate also increased significantly.In addition,cadmium reduces the number of mammary ducts in normal mice,causing damage to the mammary gland.2 Study on the proliferation and apoptosis of breast cancer cells induced by cadmiumIn this experiment,human breast cancer cells MCF-7 and MDA-231 cells were selected,and the indicators similar to BMEC and MCF-10A cells were detected.WB and immunofluorescence results showed that cadmium activated the Shh signaling pathway in tumor cells,the expression level of Glil was significantly increased,as well as BMI1,SOX2 and OCT4 protein expressions.However,different from the results of BMEC and MCF-10A cells,it was found that cadmium treatment enhanced breast cancer cell migration,and number of microspheres,but the cleavage levels of Caspase-8 and PARP were not significantly different,and the apoptosis rate by flow cytometry was not significant,indicating that cadmium could not induce apoptosis in breast cancer cells.In conclusion,in normal mammary epithelial cells the heavy metal cadmium activates the expression of Shh-Glil signaling pathway proteins,decreases the expression of stem cellrelated proteins,inhibits cell viability,migration and the number of microspheres,induces apoptosis and reduce the number of mammary ducts in mice.In breast cancer cells,cadmium activates the Shh-Glil signaling pathway,promotes the expression of stem cell-related proteins,and increases the migration and tumorigenicity of breast tumor cells.This study elucidated the differential effects of cadmium on mammary epithelial cells and cancer cells,providing new ideas and theoretical basis for improving breast development and breast cancer treatment.