Hypoxic enhancement of exosome release by breast cancer cells

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedBackground Exosomes are nanovesicles secreted by tumour cells which have roles in paracrine signalling during tumour progression, including tumour-stromal interactions, activation of proliferative pathways and bestowing immunosuppression. Hypoxia is an important feature of solid tumours which promotes tumour progression, angiogenesis and metastasis, potentially through exosome-mediated signalling. Methods Breast cancer cell lines were cultured under either moderate (1% O2) or severe (0.1% O2) hypoxia. Exosomes were isolated from conditioned media and quantitated by nanoparticle tracking analysis (NTA) and immunoblotting for the exosomal protein CD63 in order to assess the impact of hypoxia on exosome release. Hypoxic exosome fractions were assayed for miR-210 by real-time reverse transcription polymerase chain reaction and normalised to exogenous and endogenous control genes. Statistical significance was determined using the Student T test with a P value of < 0.05 considered significant. Results Exposure of three different breast cancer cell lines to moderate (1% O2) and severe (0.1% O2) hypoxia resulted in significant increases in the number of exosomes present in the conditioned media as determined by NTA and CD63 immunoblotting. Activation of hypoxic signalling by dimethyloxalylglycine, a hypoxia-inducible factor (HIF) hydroxylase inhibitor, resulted in significant increase in exosome release. Transfection of cells with HIF-1α siRNA prior to hypoxic exposure prevented the enhancement of exosome release by hypoxia. The hypoxically regulated miR-210 was identified to be present at elevated levels in hypoxic exosome fractions. Conclusions These data provide evidence that hypoxia promotes the release of exosomes by breast cancer cells, and that this hypoxic response may be mediated by HIF-1α. Given an emerging role for tumour cell-derived exosomes in tumour progression, this has significant implications for understanding the hypoxic tumour phenotype, whereby hypoxic cancer cells may release more exosomes into their microenvironment to promote their own survival and invasion.HK was recipient of a Flinders University Unibooks Honours Scholarship and the work was funded by the Flinders Medical Centre Research Foundation, the Lyn Wrigley Breast Cancer Research and Development Fund, and the Flinders Medical Centre Clinicians Special Purpose Fund

Ocenjevanje vplivov predpisov

Regulatorna funkcija države je v zadnjih nekaj desetljetjih postala predmet široke razprave v različnih forumih, pri čemer se je kot eno izmed osrednjih vprašanj izpostavilo vprašanje kakovosti regulacije. Splošno sprejeto stališčeje, da je eden izmed glavnih instrumentov, namenjenih izboljšanju le-te, analiza učinkov predpisov oz. ocenjevanje vplivov predpisov (Regulatory impact Analysis, RIA). V Sloveniji so bili pred kratkim na vladni ravni storjeni prvi konkretni koraki k sistematični uvedbi RIA, katere sestavni del bo tudi vključevanje javnosti. Na ta način bo RIA služila ne samotehničnemu vidiku reguliranja učinkovitosti in uspešnosti, ampak s transparentnostjo in odprtostjo tudi interesnemu vidiku (legitimnosti)