To investigate the effectofmiR-630 on migration and invasion oftriple-negative breast cancercellline MDA-MB-231 cellsand the mechanism.M ethodsmiR-630 wastransfected into MDA-MB-231 cells.MTT wasemployed totesttheproliferation abilityofMDA-MB-231 cells.W estern blotwasused toinvestigate theexpressionsofP27,P21 and Sox4 in MDA-MB-231 cells.Luciferaseassaywasused toconfirm whether3'-UTR ofsex determining region Y-box 4 (Sox4-3'-UTR)was the targetgene ofmiR-630援 Results Compared with the controlgroup,the Ki67 and Sox4 expressionsand the proliferation activity ofMDA-MB-231 cellswere decreased, and theP27 expression wasincreased in themiR-630 group ( < 0.05).TheluciferaseactivityoftheSox4-3'-UTR plasmid was significantly suppressed by miR-630 ( < 0.05).Over-expression ofSox4 could reverse the effectof miR-630 on MDA-MB-231 cells.ConclusionsmiR-630 inhibitsthe proliferation oftriple-negative breastcancer cellsbytargetingSox4-3'-UTR.