Programming of macrophages by UV-irradiated apoptotic cancer cells inhibits cancer progression and lung metastasis.
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ABSTRACT: Apoptotic cell clearance by phagocytes is essential in tissue homeostasis. We demonstrated that conditioned medium (CM) from macrophages exposed to apoptotic cancer cells inhibits the TGF?1-induced epithelial-mesenchymal transition (EMT), migration, and invasion of cancer cells. Apoptotic 344SQ (ApoSQ) cell-induced PPAR? activity in macrophages increased the levels of PTEN, which was secreted in exosomes. Exosomal PTEN was taken up by recipient lung cancer cells. ApoSQ-exposed CM from PTEN knockdown cells failed to enhance PTEN in 344SQ cells, restore cellular polarity, or exert anti-EMT and anti-invasive effects. The CM that was deficient in PPAR? ligands, including 15-HETE, lipoxin A4, and 15d-PGJ2, could not reverse the suppression of PPAR? activity or the PTEN increase in 344SQ cells and consequently failed to prevent the EMT process. Moreover, a single injection of ApoSQ cells inhibited lung metastasis in syngeneic immunocompetent mice with enhanced PPAR?/PTEN signaling both in tumor-associated macrophages and in tumor cells. PPAR? antagonist GW9662 reversed the signaling by PPAR?/PTEN; the reduction in EMT-activating transcription factors, such as Snai1 and Zeb1; and the antimetastatic effect of the ApoSQ injection. Thus, the injection of apoptotic lung cancer cells may offer a new strategy for the prevention of lung metastasis.
SUBMITTER: Kim YB
PROVIDER: S-EPMC6828747 | biostudies-literature | 2019 Nov
REPOSITORIES: biostudies-literature
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