Survivin is released from cancer cells via exosomes
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Inhibitor of apoptosis (IAP) and Heat shock proteins (HSPs) provide assistance in protecting cells from stresses of hypoxia, imbalanced pH, and altered metabolic and redox states commonly found in the microenvironmental mixture of tumor and nontumor cells. HSPs are upregulated, cell-surface displayed and released extracellularly in some types of tumors, a finding that until now was not shared by members of the IAP family. The IAP Survivin has been implicated in apoptosis inhibition and the regulation of mitosis in cancer cells. Survivin exists in a number of subcellular locations such as the mitochondria, cytoplasm, nucleus, and most recently, the extracellular space. Our previous work showing that extracellular survivin was able to enhance cellular proliferation, survival and tumor cell invasion provides evidence that Survivin might be secreted via an unidentified exocytotic pathway. In the present study, we describe for the first time the exosome-release of Survivin to the extracellular space both basally and after proton irradiation-induced stress. To examine whether exosomes contributed to Survivin release from cancer cells, exosomes were purified from HeLa cervical carcinoma cells and exosome quantity and Survivin content were determined. We demonstrate that although proton irradiation does not influence the exosomal secretory rate, the Survivin content of exosomes isolated from HeLa cells treated with a sublethal dose of proton irradiation (3 Gy) is significantly higher than control. These data identify a novel secretory pathway by which Survivin can be actively released from cells in both the basal and stress-induced state.
KeywordsSurvivin Exosomes Apoptosis Cancer Microenvironment
Inhibitor of apoptosis
Heat shock proteins
Lysosomal-associated membrane protein 1
X-linked inhibitor of apoptosis
American Type Culture Collection
Grant Support: NCMHD Project EXPORT Program 5P20MD001632/Project 3 (N.R. Wall). Funding was also obtained as part of a start-up package from Loma Linda University’s Center for Molecular Biology and Gene Therapy, now the Center for Health Disparities Research and Molecular Medicine (NRW) and a National Merit Test Bed (NMTB) award sponsored by the Department of the Army under Cooperative Agreement Number DAMD17-97-2-7016 (NRW). Proton irradiation was accomplished at the Loma Linda University Radiobiology Proton Treatment Facility, now the James M. Slater, MD, Proton Treatment and Research Center. The authors would like to personally thank Dr. James Slater, Dr. Daila Gridley, Steven Rightnar and Celso Perez for all their help and we dedicate this work to our dear friend and colleague Dr. Lora Green who passed away unexpectedly.
Conflict of interest
The authors declare that they have no conflict of interest.
- 27.Thery C, Clayton A, Amigorena S, Raposo G (2006) Isolation and characterization of exosomes from cell culture supernatants and biological fluids. Curr Protoc Cell Biol (Suppl 30): 3.22.21–23.22.29Google Scholar
- 42.Takata K (2006) Aquaporin-2 (AQP2): its intracellular compartment and trafficking. Cell Mol Biol (Noisy-le-grand) 52:34–39Google Scholar