Northeastern University

miR-710 as a therapeutic target in human metastatic breast cancer

Ellen Smith with Dr. Zdravka Medarova (MGH)

Studies have shown that microRNAs play a large role in the metastasis of cancers. MicroRNA 710 has been identified as a possible factor in metastasis, as it was found to be down-regulated uniformly in metastatic lesions as compared to the primary tumor regardless of the organ from which the metastases originated. We designed miR-710 nanodrugs, termed MN-miR710, consisting of iron oxide nanoparticles (MN), conjugated to miR-710 oligonucleotide mimics. When MN-miR710 nanodrugs were introduced into 4T1, a line of murine metastatic breast adenocarcinoma cells, there was robust inhibition of the cells’ viability, migration, and invasion. Additionally, decreased incidence of metastasis was implied by reduced expression of vimentin and enhanced E-cadherin, which indicates a change in the transition of epithelial cells to mesenchymal stem cells. To investigate the activity of MN-miR-710 against human cancer cells, it will be tested against 2 luciferase-expressing human breast cancer cell lines in vitro: MDA-MB-231-luc-D3H2LN, which metastasizes to the lymph nodes, and MDA231-LM2-4175, which metastasizes to the lungs. A migration assay and an invasion assay will be performed on the cell lines treated with MN-miR-710, MN-SCRmiR (an inactive control), and MN (nanoparticles without mimic). Flow cytometry will be used to evaluate senescence, differentiation, and stemness by analyzing for beta galactosidase, E-cadherin/vimentin expression, and aldehyde dehydrogenase, respectively. A cell viability assay will be performed by administering the nanodrug in combination with Paclitaxel at varying concentrations and measuring cell survival. Then, the drug will be tested in vivo in mouse models generated by implantation of the same cell lines as the in vitro experiment to investigate its effects on metastasis. The cancer cells will be orthotopically implanted into immunocompromised nude mice, and the mice will be monitored for tumor growth and metastasis via noninvasive bioluminescent imaging. After sacrifice, the organs will be examined ex vivo and the metastases will be examined for biomarkers of senescence, stemness, and viability. These projects could aid in the development of microRNA targets to prevent metastasis. If successful, this therapy could have a major impact on progressing the treatment of stage IV metastatic breast cancer beyond existing palliative care options.