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Blood vitronectin is a major activator of LIF and IL-6 in the brain through integrin-FAK and uPAR signaling.

ABSTRACT: We defined how blood-derived vitronectin (VTN) rapidly and potently activates leukemia inhibitory factor (LIF) and pro-inflammatory interleukin 6 (IL-6) in vitro and after vascular injury in the brain. Treatment with VTN (but not fibrinogen, fibronectin, laminin-111 or collagen-I) substantially increased LIF and IL-6 within 4?h in C6-astroglioma cells, while VTN-/- mouse plasma was less effective than that from wild-type mice. LIF and IL-6 were induced by intracerebral injection of recombinant human (rh)VTN in mice, but induction seen upon intracerebral hemorrhage was less in VTN-/- mice than in wild-type littermates. In vitro, VTN effects were inhibited by RGD, ?v?3 and ?v?5 integrin-blocking peptides and antibodies. VTN activated focal adhesion kinase (FAK; also known as PTK2), whereas pharmacological- or siRNA-mediated inhibition of FAK, but not PYK2, reduced the expression of LIF and IL-6 in C6 and endothelial cells and after traumatic cell injury. Dominant-negative FAK (Y397F) reduced the amount of injury-induced LIF and IL-6. Pharmacological inhibition or knockdown of uPAR (also known as PLAUR), which binds VTN, also reduced cytokine expression, possibly through a common target of uPAR and integrins. We propose that VTN leakage into tissues promotes inflammation. Integrin-FAK signaling is therefore a novel IL-6 and LIF regulation mechanism relevant to the inflammation and stem cell fields.

SUBMITTER: Keasey MP

PROVIDER: S-EPMC5826040 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Blood vitronectin is a major activator of LIF and IL-6 in the brain through integrin-FAK and uPAR signaling.

Keasey Matthew P MP Jia Cuihong C Pimentel Lylyan F LF Sante Richard R RR Lovins Chiharu C Hagg Theo T

Journal of cell science 20180202 3

We defined how blood-derived vitronectin (VTN) rapidly and potently activates leukemia inhibitory factor (LIF) and pro-inflammatory interleukin 6 (IL-6) <i>in vitro</i> and after vascular injury in the brain. Treatment with VTN (but not fibrinogen, fibronectin, laminin-111 or collagen-I) substantially increased LIF and IL-6 within 4 h in C6-astroglioma cells, while VTN<sup>-/-</sup> mouse plasma was less effective than that from wild-type mice. LIF and IL-6 were induced by intracerebral injectio ...[more]

PMID: 29222114

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Project description:BackgroundDespite effective radiotherapy for the initial stages of cancer, several studies have reported the recurrence of various cancers, including medulloblastoma. Here, we attempt to capitalize on the radiation-induced aggressive behavior of medulloblastoma cells by comparing the extracellular protease activity and the expression pattern of molecules, known to be involved in cell adhesion, migration and invasion, between non-irradiated and irradiated cells.Methodology/principal findingsWe identified an increase in invasion and migration of irradiated compared to non-irradiated medulloblastoma cells. RT-PCR analysis confirmed increased expression of uPA, uPAR, focal adhesion kinase (FAK), N-Cadherin and integrin subunits (e.g., ?3, ?5 and ?1) in irradiated cells. Furthermore, we noticed a ?2-fold increase in tyrosine phosphorylation of FAK in irradiated cells. Immunoprecipitation studies confirmed increased interaction of integrin ?1 and FAK in irradiated cells. In addition, our results show that overexpression of uPAR in cancer cells can mimic radiation-induced activation of FAK signaling. Moreover, by inhibiting FAK phosphorylation, we were able to reduce the radiation-induced invasiveness of the cancer cells. In this vein, we studied the effect of siRNA-mediated knockdown of uPAR on cell migration and adhesion in irradiated and non-irradiated medulloblastoma cells. Downregulation of uPAR reduced the radiation-induced adhesion, migration and invasion of the irradiated cells, primarily by inhibiting phosphorylation of FAK, Paxillin and Rac-1/Cdc42. As observed from the immunoprecipitation studies, uPAR knockdown reduced interaction among the focal adhesion molecules, such as FAK, Paxillin and p130Cas, which are known to play key roles in cancer metastasis. Pretreatment with uPAR shRNA expressing construct reduced uPAR and phospho FAK expression levels in pre-established medulloblastoma in nude mice.Conclusion/significanceTaken together, our results show that radiation enhances uPAR-mediated FAK signaling and by targeting uPAR we can inhibit radiation-activated cell adhesion and migration both in vitro and in vivo.

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Dataset Information

Blood vitronectin is a major activator of LIF and IL-6 in the brain through integrin-FAK and uPAR signaling.

Publications

Blood vitronectin is a major activator of LIF and IL-6 in the brain through integrin-FAK and uPAR signaling.

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