Secreted factors, identified as exosomes, enhance proliferation, migration, and invasion in MDA‐MB‐231 cells

Abstract

IntroductionTriple negative breast cancer (TNBC) is one of the most aggressive forms of five major types of breast cancer. Because TNBC mortality disproportionately affects premenopausal African American women, a health disparity exists within this group. Our research has provided insight on how the noncancerous microenvironment plays a role in TNBC proliferation, migration, and invasion. Exosomes, extracellular vesicles (30–300 nm) produced ubiquitously by mammalian cells, are secreted by noncancerous breast epithelial cells, and have been noted to enhance proliferation, migration and invasion in TNBC. Therefore, the purpose of this study is to determine if exosome‐free conditioned media (EFCM), which contains noncancerous MCF10A exosomes, enhances proliferation, migration and invasion in TNBC.MethodsMDA‐MB‐231 and MCF10A breast epithelial cells were used as cell line models. Proliferation was measured by the alamar blue proliferation assay. The transwell migration assay was used to assess migration, and the Matrigel invasion assay was used to measure migration. ExoELISA assays were also used to detect exosomes in exosome‐free conditioned media (EFCM) from MCF10A cells. MCF10A cells were serum‐starved for 24 hours, using DMEM/F‐12 with 0.5% standard or exosome‐depleted FBS (edFBS), to produce exosomal conditioned media (CM) and EFCM. This media was harvested and sterile filtered before use. MDA‐MB‐231 cells were treated with EFCM in each of the bioassays, and RPMI‐1640 was used as a control.ResultsMCF10A exosomes introduced via EFCM enhanced proliferation, migration and invasion of MDA‐MB‐231 cells.ConclusionsTaken together, our findings demonstrate that secreted factors from noncancerous MCF10A cells that have been stressed as a direct result of serum starvation are exosomes. These exosomes recruit TNBC cells to increase proliferation, migration, and invasion. The role of these exosomes in the noncancerous microenvironment is poorly understood, but these data suggest that exosomes from the noncancerous microenvironment have potential to be used in targeted therapies against triple negative breast disease.Support or Funding InformationThis research was supported by the National Institute on Minority Health and Health Disparities (NIHMHHD) of the National Institutes of Health under award number U54MD008149, sub‐award 13–14‐MB‐G007RN0A‐XU‐KPL. Technical support was provided by use of the Cellular and Molecular Biology Core facilities, supported by funding from the Louisiana Cancer Research Consortium (LCRC) and the NIH‐RCMI grant #8G12MD007595‐04 from the NIMHHD.