MM-231

1. Supplementary Figure 1 A B MM-231 * * * C * * * * * * * NS * * * * * * * * * * * E D

2. Supplementary Figure 2 MM-231-Con Si MM-231-PELP1 Si A F-Actin F-Actin+DAPI F-Actin F-Actin+DAPI ZR75-GFPVec ZR75-GFP-PELP1 B F-Actin F-Actin+DAPI F-Actin F-Actin+DAPI B ZR75 MCF7 MM-231 C PELP1-sh +200a In PELP1-sh +141 In PELP1-sh +200a In PELP1-sh +141 In PELP1-sh +141 In PELP1-sh PELP1-sh PELP1-sh PELP1-sh +200a In Con Con Con Actin Occludin N-Cadherin

3. Supplementary Figure 3 A B NS NS NS NS * * C D HDAC1-si Con-Si HDAC1 Actin HDAC2-si -236 to -107 -156 to +83 Con-Si MiR 200c-141 promoter MiR 200b-200a-429 promoter HDAC2 HDAC3-si Actin Con-Si HDAC3 Actin

4. * * Supplementary Figure 4 A B C * Tumor volume (mm3) * * * CON-sh * * * NS Weeks post injection E D CON-sh PELP1-sh CON-sh PELP1-sh GFP Ki67 positive cells (%) * * PELP1-sh CONsh PELP1sh H &E CONsh PELP1sh F G H CON-sh PELP1-sh TUNEL DAPI H&E CON-sh * %Apoptosis Vimentin PELP1-sh

5. Supplementary Figure 5 A * * * * NS NS NS NS * * * B ZR-PELP1 MCF7-PELP1 CON CON 200a mimetic 141 mimetic CON-SH 141 mimetic CON-SH 200a mimetic * * * Snail1 CDH1 C Actin

6. Supplementary Figure 6 Day 7 Day 19 Day 26 Day 34 Day 40 ZR-PELP1 ZR-PELP1-200M ZR-PELP1-141M