Figure S1. miR-489 modulates autophagy. Figure S2. Western blot analysis of autophagy flux in breast cancers. Figure S3. Validation of microarray using real-time RT-PCR analysis. Figure S4. miR-489 restoration in HCC1954 and T47D cells under starvation. Figure S5. Endogenous expression level of miR-489 in different classes of breast cancer cell lines. Figure S6. Drug sensitivity assay with cisplatin and doxorubicin. Figure S7. ULK1 restoration rescues MDA-MB-231 cells from cytotoxic effect of miR-489. Figure S8. Characterization and validation of nanoparticles in vitro and in vivo. Figure S9. Correlation of miR-489 and ULK1 mRNA expression in breast cancers. Supplemental Experimental Procedures Supplementary Table 1: Primer list and sequences. Supplementary Table 2: Demographic and histopathology data of the patient samples.
ARTICLE ABSTRACT
It is postulated that the complexity and heterogeneity in cancer may hinder most efforts that target a single pathway. Thus, discovery of novel therapeutic agents targeting multiple pathways, such as miRNAs, holds promise for future cancer therapy. One such miRNA, miR-489, is downregulated in a majority of breast cancer cells and several drug-resistant breast cancer cell lines, but its role and underlying mechanism for tumor suppression and drug resistance needs further investigation. The current study identifies autophagy as a novel pathway targeted by miR-489 and reports Unc-51 like autophagy activating kinase 1 (ULK1) and lysosomal protein transmembrane 4 beta (LAPTM4B) to be direct targets of miR-489. Furthermore, the data demonstrate autophagy inhibition and LAPTM4B downregulation as a major mechanism responsible for miR-489–mediated doxorubicin sensitization. Finally, miR-489 and LAPTM4B levels were inversely correlated in human tumor clinical specimens, and more importantly, miR-489 expression levels predict overall survival in patients with 8q22 amplification (the region in which LAPTM4B resides).Implications: These findings expand the understanding of miR-489–mediated tumor suppression and chemosensitization in and suggest a strategy for using miR-489 as a therapeutic sensitizer in a defined subgroup of resistant breast cancer patients. Mol Cancer Res; 16(9); 1348–60. ©2018 AACR.
