Study On The Mechanism Of Low Shear Stress Restoring The Viability Of Damaged Breast Tumor Cells

Breast cancer has a devastating effect on women’s lives for ages,which die from cancer metastasis largely.Hematogenous metastasis is one of the main ways for cancer to metastasize.Tumor cells will experience blood flow shear stress and anoikis,resulting in damage and decreased viability.Nevertheless,there are still a small part of tumor cells that can maintain viability and complete transendothelial migration to achieve metastasis during the tiny shear stress of the capillaries.Therefore,it is of vital importance to study the changes in viability of damaged cells during the low shear stress(LSS).In this study,high shear stress(HSS)was applied to simulate blood circulation to damage cells and reduce the cell viability,which was detected again after LSS loading.Meanwhile,the role of mitochondria in this process was explored.The main contents and results were as follows:(1)LSS improved the viability of damaged cells significantly.Cells were exposed to HSS(60 dyn/cm~2)for 4 h and LSS(0.5 dyn/cm~2)for 8 h in order to investigate the effect of LSS on the viability of damaged cells,which was detected by MTS.The results showed that the viability of cells decreased by 59.0±3.2%when exposed to HSS for 4 h.On this basis,the cell viability increased significantly by 16.8±4.2%when exposed to LSS for 8 h.(2)LSS improved the viability and mitochondrial function of damaged cells by decreasing the expression of cytochrome c(Cyt C).Cell viability is related to mitochondrial function closely.In order to explore the role of mitochondria in the process of LSS restorating the viability of damaged cells,the copy number of mitochondrial DNA(mt DNA)and the levels of reactive oxygen species(ROS)were detected at the end of HSS and LSS loading.The role of mitochondria was verified by protecting and inhibiting the mitochondrial function.The results showed that LSS recovered cell viability by increasing the mt DNA copy number and decreasing the high expression of ROS.The expressions of proteins:p53,peroxisome proliferator-activated receptor-gamma coactivator-1alpha(PGC-1α),nuclear respiratory factor-1(NRF-1)and Cyt C were detected by western blot to further investigate the potential mechanism of the process.Then the expression of Cyt C was inhibited and activated to verify its role in LSS restoring mitochondrial function of damaged cells.The results showed that HSS induced high expression of suppressor gene p53,mitochondrial biogenesis related protiens PGC-1αand NRF-1 and mitochondrial respiratory related protein Cyt C.LSS inhibited the high expression of p53,PGC-1α,NRF-1 and Cyt C in damaged cells.Moreover,LSS restored the viability and mitochondrial function of damaged cells to a certain extent by reducing the high expression of Cyt C.In summary,this paper explored the mechanism of LSS recovering the viability of damaged cells.It was found that LSS restored the mitochondrial function to recover the viability of damaged cells by inhibiting the high expression of Cyt C to a certain extent.The results of this study were expected to provide a theoretical basis for reducing the survival rate of cells in hematogenous metastasis.