Increasing　evidence　confirms　that　aberrant　miRNA　expression　contributes　to　breast　cancer　(BC)　development　and　progression.　However,　the　roles　of　different　miRNAs　in　BC　remain　to　be　explored.　In　the　present　study,　we　demonstrated　that　miR-1297　expression　was　increased　in　BC　tissues　and　cell　lines.　Our　clinical　analysis　revealed　that　the　upregulated　miR-1297　expression　was　significantly　correlated　with　poor　prognostic　features　including　advanced　TNM　stage　and　larger　tumor　size.　Moreover,　we　found　that　miR-1297　was　a　novel　independent　prognostic　marker　for　predicting　5-year　survival　of　BC　patients.　The　ectopic　overexpression　of　miR-1297　promoted　cell　proliferation,　cell　cycle　progression　and　inhibited　apoptosis　while　miR-1297　knockdown　reversed　the　effect.　In　addition,　miR-1297　modulated　PTEN　by　directly　binding　to　its　3＇-UTR,　resulting　in　activation　of　AKT　signaling.　In　clinical　samples　of　BC,　miR-1297　inversely　correlated　with　PTEN,　which　was　downregulated　in　BC.　Alternation　of　PTEN　expression　or　AKT　inhibitor　at　least　partially　abolished　the　biological　effects　of　miR-1297　on　BC　cells.　In　conclusion,　our　results　indicated　that　miR-1297　functioned　as　an　oncogene　in　regulating　the　proliferation,　cell　cycle　and　apoptosis　of　BC　via　targeting　PTEN/PI3K/AKT　signaling,　and　may　represent　a　novel　potential　therapeutic　target　and　prognostic　marker　for　BC.