RESUMEN
Improved detection of breast cancer using highly sensitive, tumor-specific imaging would facilitate diagnosis, surveillance and assessment of response to treatment. We conjugated osteopontin peptide to an infrared fluorescent dye to serve as a contrast agent for detection of breast cancer by multispectral optoacoustic tomography (MSOT). Selective binding of the osteopontin-based probe was identified using flow cytometry and near infrared fluorescent imaging in triple negative and HER2 positive breast cancer cell lines in vitro. Osteopontin-750 accumulation was evaluated in vivo using MSOT with secondary confirmation of signal accumulation using near infrared fluorescent imaging. The osteopontin-based probe demonstrated binding to breast cancer cells in vitro. Similarly, after intravenous administration of the osteopontin-750 probe, it accumulated preferentially in the subcutaneous breast tumor in nude mice (557 MSOT a.u. compared to untargeted organs such as kidney (53.7 MSOT a.u.) and liver (32.1 MSOT a.u.). At 2.5 h post-injection, signal intensity within the tumor was 9.7 and 17 times greater in the tumor bed than in the kidney or liver, respectively. Fluorescence imaging ex vivo comparing tumor signal to that of nontarget organs confirmed the results in vivo. MSOT imaging demonstrated selective accumulation of the fluorescent osteopontin targeting probe to tumor sites both in vitro and in vivo, and provided high-resolution images. Further development of this tool is promising for advanced diagnostic imaging, disease surveillance and therapeutic models that limit nontarget toxicity.
Asunto(s)
Neoplasias de la Mama , Osteopontina/química , Técnicas Fotoacústicas , Animales , Neoplasias de la Mama/clasificación , Neoplasias de la Mama/diagnóstico , Línea Celular Tumoral , Modelos Animales de Enfermedad , Femenino , Humanos , RatonesRESUMEN
Acquired resistance to chemotherapy remains a major stumbling block in cancer treatment. Chronic inflammation has a crucial role in induction of chemoresistance and results, in part, from the induction and expansion of inflammatory cells that include myeloid-derived suppressor cells (MDSCs) and IL-13+ Th2 cells. The mechanisms that lead to induction of activated MDSCs and IL-13+ Th2 cells have not yet been identified. Here we demonstrated that doxorubicin (DOX) treatment of 4T1 breast tumor-bearing mice led to the induction of IL-13R+miR-126a+ MDSCs (DOX-MDSC). DOX-MDSC promote breast tumor lung metastasis through MDSC miR-126a+ exosomal-mediated induction of IL-13+ Th2 cells and tumor angiogenesis. The induction of DOX-MDSC is regulated in a paracrine manner. DOX treatment not only increases interleukin (IL)-33 released from breast tumor cells, which is crucial for the induction of IL-13+ Th2 cells, but it also participates in the induction of IL-13 receptors and miR-126a expressed on/in the MDSCs. IL-13 released from IL-13+Th2 cells then promotes the production of DOX-MDSC and MDSC miR-126a+ exosomes via MDSC IL-13R. MDSC miR-126a+ exosomes further induce IL13+ Th2 cells in a positive feed-back loop manner. We also showed that MDSC miR-126a rescues DOX-induced MDSC death in a S100A8/A9-dependent manner and promotes tumor angiogenesis. Our findings provide insight into the MDSC exosomal-mediated chemoresistance mechanism, which will be useful for the design of inhibitors targeting the blocking of induction of miR-126a+ MDSCs.