title: Hypoxic tumor cell modulates its microenvironment to enhance angiogenic and metastatic potential by secretion of proteins and exosomes.
abstract: Under hypoxia, tumor cells produce a secretion that modulates their microenvironment to facilitate tumor angiogenesis and metastasis. Here, we observed that hypoxic or reoxygenated A431 carcinoma cells exhibited enhanced angiogenic and metastatic potential such as reduced cell-cell and cell-extracellular matrix adhesion, increased invasiveness, and production of a secretion with increased chorioallantoic membrane angiogenic activity. Consistent with these observations, quantitative proteomics revealed that under hypoxia the tumor cells secreted proteins involved in angiogenesis, focal adhesion, extracellular matrix-receptor interaction, and immune cell recruitment. Unexpectedly, the secreted proteins were predominantly cytoplasmic and membrane proteins. Ultracentrifugation at 100,000 x g precipitated 54% of the secreted proteins and enriched for many exosome-associated proteins such as the tetraspanins and Alix and also proteins with the potential to facilitate angiogenesis and metastasis. Two tetraspanins, CD9 and CD81, co-immunoprecipitated. Together, these data suggested that tumor cells secrete proteins and exosomes with the potential to modulate their microenvironment and facilitate angiogenesis and metastasis.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore.
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Park
authors.forename: Hon Sen
authors.initials: HS
authors.lastname: Tan
authors.forename: Arnab
authors.initials: A
authors.lastname: Datta
authors.forename: Ruenn Chai
authors.initials: RC
authors.lastname: Lai
authors.forename: Huoming
authors.initials: H
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Meng
authors.forename: Sai Kiang
authors.initials: SK
authors.lastname: Lim
authors.forename: Siu Kwan
authors.initials: SK
authors.lastname: Sze
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D016000:Cluster Analysis; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D055354:Exosomes / Q000378:metabolism*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D013058:Mass Spectrometry; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology*; D009389:Neovascularization, Pathologic / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D040081:Protein Array Analysis; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D017077:Culture Media, Conditioned; D016207:Cytokines; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D010100:Oxygen