OBJECTIVE:To investigate the efficacy of Biejia(Carapax Trionycis) and Ezhu (Rhizoma Curcumae Phaeocaulis) couplet medicine on epithelial-mesen-chymal transition (EMT),invasion and migration of MDA-MB-231 triple negative breast cancer (TNBC)cells based on PI3K/Akt/mTOR signaling pathway.METHODS:MDA-MB-231 cells were treated with different medicated serum as Biejia-,Ezhu-,Biejia-Ezhu (B J-,EZ-,BJ-EZ-) groups,intervened with no drug rat serum and paclitaxel with final concentration of 33 nM (IC50) as negative and posi-tive control (NC and PC) groups.CCK-8 assay,scratch test,and Transwell assay were used to ex-amine cell proliferation,invasion,and migration.The expression of E-cadherin,N-cadherin,Vimen-tin,MMP-2,MMP-9,PI3K,Akt,p-Akt,mTOR,and p-mTOR was determined by Western blot,and the mRNA expression of PI3K,Akt and mTOR was deter-mined by real-time polymerase chain reaction.RESULTS:BJ-EZ group inhibited proliferation after 24,48,and 72 h compared with the NC group (P ＜0.05,＜ 0.01 or ＜ 0.001) and reduced the invasion and migration of MDA-MB-231 cells (P ＜ 0.01 or ＜0.001).In addition,BJ-EZ group upregulated the ex-pression of E-cadherin,downregulated the expres-sion of N-cadherin,Vimentin,MMP-2,and MMP-9(P ＜ 0.05,P ＜ 0.01 or P ＜ 0.001),and inhibited the mRNA and protein expression of PI3K,Akt (p-Akt),mTOR (p-mTOR) (P ＜ 0.05,＜ 0.01 or ＜ 0.001).CONCLUSION:Biejia (Carapax Trionycis) and Ezhu(Rhizoma Curcumae Phaeocaulis) couplet medicine can inhibit the proliferation,invasion,migration and EMT of MDA-MB-231 cells through PI3K/Akt/mTOR signaling pathway,and the effect is better than that of Biejia (Carapax Trionycis) or Ezhu (Rhi-zoma Curcumae Phaeocaulis) alone.