PI3K p110γ overexpression in idiopathic pulmonary fibrosis lung tissue and fibroblast cells: in vitro effects of its inhibition

Idiopathic pulmonary fibrosis (IPF) is a progressive fibroproliferative disease whose molecular pathogenesis remains unclear. In a recent paper, we demonstrated a key role for the PI3K pathway in both proliferation and differentiation into myofibroblasts of normal human lung fibroblasts treated with TGF-β. In this research, we assessed the expression of class I PI3K p110 isoforms in IPF lung tissue as well as in tissue-derived fibroblast cell lines. Moreover, we investigated the in vitro effects of the selective inhibition of p110 isoforms on IPF fibroblast proliferation and fibrogenic activity. IHC was performed on normal and IPF lung tissue. Expression levels of PI3K p110 isoforms were evaluated by western blot and flow cytometry analysis. Fibroblast cell lines were established from both normal and IPF tissue and the effects of selective pharmacological inhibition as well as specific gene silencing by small interfering RNAs were studied in vitro. No significant differences between normal and IPF tissue/tissue-derived fibroblasts were observed for the expression of PI3K p110 α, β and δ isoforms whereas p110γ was more greatly expressed in both IPF lung homogenates and ex vivo fibroblast cell lines. Myofibroblasts and bronchiolar basal cells in IPF lungs exhibited strong immunoreactivity for p110γ. Positive staining for the markers of proliferation proliferating cell nuclear antigen and cyclin D1 was also shown in cells of fibrolastic foci. Furthermore, both p110γ pharmacological inhibition and gene silencing were able to significantly inhibit proliferation rate as well as α-SMA expression in IPF fibroblasts. Our data suggest that PI3K p110γ isoform may have an important role in the etio-pathology of IPF and can be a specific pharmacological target.

[1]  J. Halstead,et al.  Nuclear inositides: inconsistent consistencies , 2000, Cellular and Molecular Life Sciences CMLS.

[2]  I. Adcock,et al.  Phosphatidylinositol 3-kinase isoforms as targets in respiratory disease , 2010, Therapeutic advances in respiratory disease.

[3]  G. Raghu,et al.  Idiopathic pulmonary fibrosis: a disease with similarities and links to cancer biology , 2010, European Respiratory Journal.

[4]  R. Strawderman,et al.  Steroids in idiopathic pulmonary fibrosis: a prospective assessment of adverse reactions, response to therapy, and survival. , 2001, The American journal of medicine.

[5]  J. Halstead,et al.  Inositol lipids are regulated during cell cycle progression in the nuclei of murine erythroleukaemia cells. , 2001, The Biochemical journal.

[6]  E. B. Meltzer,et al.  Severe lung fibrosis requires an invasive fibroblast phenotype regulated by hyaluronan and CD44 , 2011, The Journal of experimental medicine.

[7]  V. Poletti,et al.  Migratory marker expression in fibroblast foci of idiopathic pulmonary fibrosis , 2006, Respiratory research.

[8]  S. Phan.  The myofibroblast in pulmonary fibrosis. , 2002, Chest.

[9]  M. L. R. D. Christenson,et al.  An Official ATS/ERS/JRS/ALAT Statement: Idiopathic Pulmonary Fibrosis: Evidence-based Guidelines for Diagnosis and Management , 2012 .

[10]  P. Shepherd,et al.  Phosphatidylinositol 3-Kinase Isoform-Specific Effects in Airway Mesenchymal Cell Function , 2011, Journal of Pharmacology and Experimental Therapeutics.

[11]  G. Guillon,et al.  Characterization of a G Protein-activated Phosphoinositide 3-Kinase in Vascular Smooth Muscle Cell Nuclei* , 2001, The Journal of Biological Chemistry.

[12]  H. Friess,et al.  Key Role of Phosphoinositide 3-Kinase Class IB in Pancreatic Cancer , 2010, Clinical Cancer Research.

[13]  V. Pulkkinen,et al.  Transcription factor GATA-6 is expressed in quiescent myofibroblasts in idiopathic pulmonary fibrosis. , 2010, American journal of respiratory cell and molecular biology.

[14]  Pier Paolo Pandolfi,et al.  The PTEN–PI3K pathway: of feedbacks and cross-talks , 2008, Oncogene.

[15]  Paul J. Friedman,et al.  American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias. This joint statement of the American Thoracic Society (ATS), and the European Respiratory Society (ERS) was adopted by the ATS board of directors , 2002, American journal of respiratory and critical care medicine.

[16]  J. McDonald,et al.  The roles of the myofibroblast in idiopathic pulmonary fibrosis. Ultrastructural and immunohistochemical features of sites of active extracellular matrix synthesis. , 1991, The American journal of pathology.

[17]  G. Giannelli,et al.  PI3K class IB controls the cell cycle checkpoint promoting cell proliferation in hepatocellular carcinoma , 2012, International journal of cancer.

[18]  B. Vanhaesebroeck,et al.  The emerging mechanisms of isoform-specific PI3K signalling , 2010, Nature Reviews Molecular Cell Biology.

[19]  O. Delattre,et al.  A Sensitized RNA Interference Screen Identifies a Novel Role for the PI3K p110γ Isoform in Medulloblastoma Cell Proliferation and Chemoresistance , 2011, Molecular Cancer Research.

[20]  C. Vancheri,et al.  Resveratrol inhibits transforming growth factor-β–induced proliferation and differentiation of ex vivo human lung fibroblasts into myofibroblasts through ERK/Akt inhibition and PTEN restoration , 2011, Experimental lung research.

[21]  C. Abrams,et al.  Agonists Cause Nuclear Translocation of Phosphatidylinositol 3-Kinase γ , 1999, The Journal of Biological Chemistry.

[22]  C. B. Alexander,et al.  Loss of fibroblast Thy-1 expression correlates with lung fibrogenesis. , 2005, The American journal of pathology.

[23]  Lewis C Cantley,et al.  The phosphoinositide 3-kinase pathway. , 2002, Science.

[24]  D. Frank,et al.  FAK and WNT signaling: the meeting of two pathways in cancer and development. , 2011, Anti-cancer agents in medicinal chemistry.

[25]  Yuquan Wei,et al.  A phosphoinositide 3-kinase-gamma inhibitor, AS605240 prevents bleomycin-induced pulmonary fibrosis in rats. , 2010, Biochemical and biophysical research communications.

[26]  J. Myers,et al.  Idiopathic pulmonary fibrosis: clinical relevance of pathologic classification. , 1998, American journal of respiratory and critical care medicine.

[27]  C. Henke,et al.  Pathologic caveolin-1 regulation of PTEN in idiopathic pulmonary fibrosis. , 2010, The American journal of pathology.

[28]  G. Rewcastle,et al.  Effects of acutely inhibiting PI3K isoforms and mTOR on regulation of glucose metabolism in vivo , 2011, The Biochemical journal.

[29]  C. Vancheri,et al.  Inhibition of PI3K Prevents the Proliferation and Differentiation of Human Lung Fibroblasts into Myofibroblasts: The Role of Class I P110 Isoforms , 2011, PloS one.

[30]  I. Adcock,et al.  Targeting phosphoinositide-3-kinase-delta with theophylline reverses corticosteroid insensitivity in chronic obstructive pulmonary disease. , 2010, American journal of respiratory and critical care medicine.

[31]  M. Jordana,et al.  Heterogeneous proliferative characteristics of human adult lung fibroblast lines and clonally derived fibroblasts from control and fibrotic tissue. , 1988, The American review of respiratory disease.

[32]  A. Katzenstein,et al.  Proliferative activity in fibrosing lung diseases: a comparative study of Ki-67 immunoreactivity in diffuse alveolar damage, bronchiolitis obliterans-organizing pneumonia, and usual interstitial pneumonia. , 2009, Human pathology.

[33]  W. Thurlbeck,et al.  Idiopathic pulmonary fibrosis: relationship between histopathologic features and mortality. , 2001, American journal of respiratory and critical care medicine.

[34]  K. Preissner,et al.  Comparative proteomic analysis of lung tissue from patients with idiopathic pulmonary fibrosis (IPF) and lung transplant donor lungs. , 2011, Journal of proteome research.