ObjectiveTo investigate the effect of Liuwei Dihuangwan drug-containing serum （LDP） on epithelial-mesenchymal transition （EMT） and the expression of cancer stem cell （CSC） properties in 4T1 cells from triple-negative breast cancer by intervening myeloid-derived suppressor cells （MDSCs）. MethodsSPF-grade female SD rats were randomly divided into three groups， which were given 0.39， 1.94， 3.89 g·kg^-1·d^-1 suspension of Liuwei Dihuangwan for 7 days， respectively， to prepare low-， medium-， and high-dose LDPs. 4T1 cells were inoculated subcutaneously into the mammary glands of SPF-grade female Balb/c mice to construct a transplantation tumor model. Bone marrow cells were extracted from the tibia and femur and induced into MDSCs in vitro. The cell counting kit-8 （CCK-8） assay was used to detect the viability of 4T1 cells and MDSCs. The number of MDSCs and the expressions of CSC surface markers CD44 and CD24 in 4T1 cells were detected by flow cytometry （FC）. The migration， invasion， and proliferation of 4T1 cells were detected by cell scratch assay， Transwell invasion assay， and plate colony-forming assay， respectively. Western blot （WB） was used to detect the protein expression of transforming growth factor-β （TGF-β）， nuclear factor-κB （NF-κB）， C-X-C motif chemokine ligand 2 （CXCL2）， E-cadherin， and N-cadherin. The expression of EMT-related proteins E-cadherin and N-cadherin were detected by immunofluorescence （IF）. ResultsCompared with the normal group， LDP showed no significant inhibitory effect on the cell viability of 4T1 cells， but it significantly reduced the viability and number of MDSCs and reduced the number of MDSCs， as well as the expression of TGF-β （P<0.05， P<0.01）. The migration， invasion， and proliferation of 4T1 cells were increased after co-culture with MDSCs （P<0.05， P<0.01）. The expressions of NF-κB， CXCL2， and N-cadherin and the proportion of CSC （CD44⁺CD24^-） were elevated （P<0.05， P<0.01）， while the expression of E-cadherin was decreased （P<0.05）. After the intervention of MDSCs with LDP， followed by co-culture with 4T1 cells， the migration， invasion， and proliferation of 4T1 cells were obviously reduced （P<0.01）. The expressions of NF-κB， CXCL2， and N-cadherin were decreased （P<0.05， P<0.01）， and the expression of E-cadherin was increased （P<0.05， P<0.01）. There was no statistical difference in the proportion of CSC （CD44⁺CD24^-） in 4T1 cells. However， the proportion of CSC （CD44⁺CD24^-） was decreased in the co-culture system of 4T1 cells and MDSCs with LDP intervention （P<0.05， P<0.01）. ConclusionLDP can reduce the viability and number of MDSCs and the expression of TGF-β， NF-κB， and CXCL2， reverse EMT， and reduce the characteristic expression of CSC to inhibit the migration， invasion， and proliferation of 4T1 cells.

ObjectiveTo investigate the effect of Liuwei Dihuangwan drug-containing serum （LDP） on epithelial-mesenchymal transition （EMT） and the expression of cancer stem cell （CSC） properties in 4T1 cells from triple-negative breast cancer by intervening myeloid-derived suppressor cells （MDSCs）. MethodsSPF-grade female SD rats were randomly divided into three groups， which were given 0.39， 1.94， 3.89 g·kg^-1·d^-1 suspension of Liuwei Dihuangwan for 7 days， respectively， to prepare low-， medium-， and high-dose LDPs. 4T1 cells were inoculated subcutaneously into the mammary glands of SPF-grade female Balb/c mice to construct a transplantation tumor model. Bone marrow cells were extracted from the tibia and femur and induced into MDSCs in vitro. The cell counting kit-8 （CCK-8） assay was used to detect the viability of 4T1 cells and MDSCs. The number of MDSCs and the expressions of CSC surface markers CD44 and CD24 in 4T1 cells were detected by flow cytometry （FC）. The migration， invasion， and proliferation of 4T1 cells were detected by cell scratch assay， Transwell invasion assay， and plate colony-forming assay， respectively. Western blot （WB） was used to detect the protein expression of transforming growth factor-β （TGF-β）， nuclear factor-κB （NF-κB）， C-X-C motif chemokine ligand 2 （CXCL2）， E-cadherin， and N-cadherin. The expression of EMT-related proteins E-cadherin and N-cadherin were detected by immunofluorescence （IF）. ResultsCompared with the normal group， LDP showed no significant inhibitory effect on the cell viability of 4T1 cells， but it significantly reduced the viability and number of MDSCs and reduced the number of MDSCs， as well as the expression of TGF-β （P<0.05， P<0.01）. The migration， invasion， and proliferation of 4T1 cells were increased after co-culture with MDSCs （P<0.05， P<0.01）. The expressions of NF-κB， CXCL2， and N-cadherin and the proportion of CSC （CD44⁺CD24^-） were elevated （P<0.05， P<0.01）， while the expression of E-cadherin was decreased （P<0.05）. After the intervention of MDSCs with LDP， followed by co-culture with 4T1 cells， the migration， invasion， and proliferation of 4T1 cells were obviously reduced （P<0.01）. The expressions of NF-κB， CXCL2， and N-cadherin were decreased （P<0.05， P<0.01）， and the expression of E-cadherin was increased （P<0.05， P<0.01）. There was no statistical difference in the proportion of CSC （CD44⁺CD24^-） in 4T1 cells. However， the proportion of CSC （CD44⁺CD24^-） was decreased in the co-culture system of 4T1 cells and MDSCs with LDP intervention （P<0.05， P<0.01）. ConclusionLDP can reduce the viability and number of MDSCs and the expression of TGF-β， NF-κB， and CXCL2， reverse EMT， and reduce the characteristic expression of CSC to inhibit the migration， invasion， and proliferation of 4T1 cells.