Keratinocyte growth factor induces Akt kinase activity and inhibits Fas-mediated apoptosis in A 549 lung epithelial cells

Bao, Shenying, Yijie Wang, Patricia Sweeney, Alpana Chaudhuri, Andrea I. Doseff, Clay B. Marsh, and Daren L. Knoell. Keratinocyte growth factor induces Akt kinase activity and inhibits Fas-mediated apoptosis in A549 lung epithelial cells. Am J Physiol Lung Cell Mol Physiol 288: L36–L42, 2005. First published September 3, 2004; doi:10.1152/ajplung.00309.2003.—Acute respiratory distress syndrome (ARDS) is a syndrome characterized by the rapid influx of protein-rich edema fluid into the air spaces. The magnitude of alveolar epithelial cell injury is a key determinant of disease severity and an important predictor of patient outcome. The alveolar epithelium is positioned at the interface of the host response in the initiation, progression, and recovery phase of the disease. Keratinocyte growth factor (KGF) is a potent survival factor unique to the epithelium that promotes lung epithelial cell survival, accelerates wound closure, and reduces fibrosis. We therefore hypothesized that KGF preserves lung function by inhibiting apoptosis through activation of a signal transduction pathway responsible for cell survival. To test this hypothesis we determined that KGF inhibits death following Fas activation, a relevant apoptosis pathway, and then determined that cell survival is mediated through activation of the phosphatidylinositol 3 -kinase (PI3K)/Akt kinase signal transduction pathway. We found that KGF induces a doseand time-dependent increase in Akt kinase activity and that, as expected, activation of Akt via KGF is PI3K dependent. KGF inhibited Fas-induced apoptosis as measured by a reduction in apoptotic cells and caspase-3 activity. This investigation supports our original hypothesis that KGF protects the lung epithelium by inhibiting apoptosis and that protection occurs through activation of PI3K/Akt-mediated cell survival pathway. Our results are in agreement with other reports that identify the PI3K/Akt axis as a key intracellular pathway in the lung epithelium that may serve as a therapeutic target to preserve epithelial integrity during inflammation.

[1]  R. Mason,et al.  Keratinocyte growth factor stimulates alveolar type II cell proliferation through the extracellular signal-regulated kinase and phosphatidylinositol 3-OH kinase pathways. , 2004, American journal of respiratory cell and molecular biology.

[2]  C. Sugimoto,et al.  PI3K/Akt and apoptosis: size matters , 2003, Oncogene.

[3]  Simon C Watkins,et al.  Inducible expression of keratinocyte growth factor (KGF) in mice inhibits lung epithelial cell death induced by hyperoxia , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[4]  G. Zimmerman,et al.  Fas and fas ligand are up-regulated in pulmonary edema fluid and lung tissue of patients with acute lung injury and the acute respiratory distress syndrome. , 2002, The American journal of pathology.

[5]  M. Matthay,et al.  Keratinocyte and hepatocyte growth factors in the lung: roles in lung development, inflammation, and repair. , 2002, American journal of physiology. Lung cellular and molecular physiology.

[6]  W. Liles,et al.  Fas/Fas Ligand System Mediates Epithelial Injury, but Not Pulmonary Host Defenses, in Response to Inhaled Bacteria , 2001, Infection and Immunity.

[7]  K. Kooguchi,et al.  Fas/FasL-dependent apoptosis of alveolar cells after lipopolysaccharide-induced lung injury in mice. , 2001, American journal of respiratory and critical care medicine.

[8]  Yunbi Lu,et al.  Activated Akt Protects the Lung from Oxidant-Induced Injury and Delays Death of Mice , 2001, The Journal of experimental medicine.

[9]  G. V. Vande Woude,et al.  Anti-apoptotic signaling by hepatocyte growth factor/Met via the phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase pathways. , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[10]  K. Kuwano,et al.  Soluble form of fas and fas ligand in BAL fluid from patients with pulmonary fibrosis and bronchiolitis obliterans organizing pneumonia. , 2000, Chest.

[11]  D. Williams,et al.  Rac2 stimulates Akt activation affecting BAD/Bcl-XL expression while mediating survival and actin function in primary mast cells. , 2000, Immunity.

[12]  E. Kandel,et al.  The regulation and activities of the multifunctional serine/threonine kinase Akt/PKB. , 1999, Experimental cell research.

[13]  E. Chi,et al.  Soluble Fas ligand induces epithelial cell apoptosis in humans with acute lung injury (ARDS). , 1999, Journal of immunology.

[14]  S. Nagata,et al.  Essential roles of the Fas-Fas ligand pathway in the development of pulmonary fibrosis. , 1999, The Journal of clinical investigation.

[15]  Vishva Dixit,et al.  Vascular Endothelial Growth Factor Regulates Endothelial Cell Survival through the Phosphatidylinositol 3′-Kinase/Akt Signal Transduction Pathway , 1998, The Journal of Biological Chemistry.

[16]  K. Rabe,et al.  Expression of Fas (CD95) and FasL (CD95L) in human airway epithelium. , 1998, American journal of respiratory cell and molecular biology.

[17]  G R Bernard,et al.  The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome. , 1998, American journal of respiratory and critical care medicine.

[18]  G. Salvesen,et al.  Caspase Cleavage of Keratin 18 and Reorganization of Intermediate Filaments during Epithelial Cell Apoptosis , 1997, The Journal of cell biology.

[19]  K. Kuwano,et al.  Induction of apoptosis and pulmonary fibrosis in mice in response to ligation of Fas antigen. , 1997, American journal of respiratory cell and molecular biology.

[20]  N. Anderson,et al.  Fas expression in pulmonary alveolar type II cells. , 1997, The American journal of physiology.

[21]  D. Kamp,et al.  KGF facilitates repair of radiation-induced DNA damage in alveolar epithelial cells. , 1997, The American journal of physiology.

[22]  A. Klippel,et al.  Antiapoptotic signalling by the insulin-like growth factor I receptor, phosphatidylinositol 3-kinase, and Akt , 1997, Molecular and cellular biology.

[23]  R. Deterding,et al.  Keratinocyte growth factor reduces lung damage due to acid instillation in rats. , 1996, American journal of respiratory cell and molecular biology.

[24]  C. Heldin,et al.  Ligand-induced dimerization of growth factor receptors: variations on the theme. , 1996, Cytokine & growth factor reviews.

[25]  T. Pawson,et al.  SH2 domains recognize specific phosphopeptide sequences , 1993, Cell.

[26]  J. Rubin,et al.  Human KGF is FGF-related with properties of a paracrine effector of epithelial cell growth. , 1989, Science.

[27]  J. Rubin,et al.  Purification and characterization of a newly identified growth factor specific for epithelial cells. , 1989, Proceedings of the National Academy of Sciences of the United States of America.

[28]  Barry H. Smith,et al.  A continuous tumor‐cell line from a human lung carcinoma with properties of type II alveolar epithelial cells , 1976, International journal of cancer.

[29]  A. Doseff,et al.  Opposing effect by cytokines on Fas-mediated apoptosis in A549 lung epithelial cells. , 2002, American journal of respiratory cell and molecular biology.

[30]  D. Kamp,et al.  Keratinocyte growth factor promotes alveolar epithelial cell DNA repair after H2O2 exposure. , 1998, The American journal of physiology.

[31]  K. Kuwano,et al.  Apoptosis and expression of Fas/Fas ligand mRNA in bleomycin-induced pulmonary fibrosis in mice. , 1997, American journal of respiratory cell and molecular biology.

[32]  T. Fleming,et al.  Determination of ligand-binding specificity by alternative splicing: two distinct growth factor receptors encoded by a single gene. , 1992, Proceedings of the National Academy of Sciences of the United States of America.