title: Tumor-stromal cross talk: direct cell-to-cell transfer of oncogenic microRNAs via tunneling nanotubes.
abstract: Tunneling nanotubes (TnTs) represent a novel mechanism by which intercellular components such as proteins, Golgi vesicles, and mitochondria can be transferred from cell to cell in the complex tumor microenvironment. Here, we report data showing that microRNAs (miRNAs) are transferred through TnTs in osteosarcoma (OS) and ovarian cancer as in vitro model systems. miRNA array analysis demonstrated significant upregulation of miR-19a in OS tumors resected from human patients, and differential expression of miR-199a in ovarian cancer cell lines resistant or sensitive to platinum chemotherapy. K7M2 murine OS cells were transfected with miR-19a and cultured with nontransfected K7M2 cells in low-serum, hyperglycemic medium for up to 72 hours to induce TnT formation. miRNA transfer via TnTs was detected by time-lapse microscopic imaging. miR-19a was also transported via TnTs connecting transfected K7M2 cells and nontransfected stromal MC3T3 murine osteoblast cells. Similar findings were observed in studies of TnT-mediated transport of miR-199a among SKOV3 ovarian cancer cells and nonmalignant immortalized ovarian epithelial cells. To quantify TnT-mediated transport of miRNAs, we used modified Boyden chambers to separate miR-19a-transfected K7M2 cells (top chamber) and DiI-labeled MC3T3 cells (bottom chamber) compared with open culture of these cells. Fluorescence-activated cell sorting analysis of cells collected after 48 hours of culture indicated that miR-19a-positive MC3T3 cells were 3-fold higher in open culture; this finding suggests that miR-19a transfer occurred via TnTs, exclusive of other forms of cell-cell communication. These studies demonstrate that TnTs mediate direct transfer of genetic material between tumor and stromal cells.
authors.affiliation: Division of Hematology, Oncology and Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minn.
authors.forename: Venugopal
authors.initials: V
authors.lastname: Thayanithy
authors.affiliation: Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, University of Minnesota, Minneapolis, Minn.
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Dickson
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Minnesota, Minneapolis, Minn.
authors.forename: Clifford
authors.initials: C
authors.lastname: Steer
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn.
authors.forename: Subbaya
authors.initials: S
authors.lastname: Subramanian
authors.affiliation: Division of Hematology, Oncology and Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minn. Electronic address: emil-lou@umn.edu.
authors.forename: Emil
authors.initials: E
authors.lastname: Lou
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002450:Cell Communication; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D005260:Female; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology*; D043942:Nanotubes; D012516:Osteosarcoma / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000378:metabolism*; D014162:Transfection; D059016:Tumor Microenvironment
chemical_list: D035683:MicroRNAs