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          Institute: MPI für Herz- und Lungenforschung (W. G. Kerckhoff Institut)     Collection: Yearbook_2014     Display Documents

ID: 682163.0, MPI für Herz- und Lungenforschung (W. G. Kerckhoff Institut) / Yearbook_2014
Phosphodiesterase-4 promotes proliferation and angiogenesis of lung cancer by crosstalk with HIF
Authors:Pullamsetti, S. S.; Banat, G. A.; Schmall, A.; Szibor, M.; Pomagruk, D.; Hanze, J.; Kolosionek, E.; Wilhelm, J.; Braun, T.; Grimminger, F.; Seeger, W.; Schermuly, R. T.; Savai, R.
Date of Publication (YYYY-MM-DD):2013-02-28
Journal Abbrev.:Oncogene
Issue / Number:9
Start Page:1121
End Page:1134
Audience:Not Specified
Abstract / Description:Lung cancer is the leading cause of cancer death worldwide. Recent data suggest that cyclic nucleotide phosphodiesterases (PDEs) are relevant in various cancer pathologies. Pathophysiological role of phosphodiesterase 4 (PDE4) with possible therapeutic prospects in lung cancer was investigated. We exposed 10 different lung cancer cell lines (adenocarcinoma, squamous and large cell carcinoma) to hypoxia and assessed expression and activity of PDE4 by real-time PCR, immunocytochemistry, western blotting and PDE activity assays. Expression and activity of distinct PDE4 isoforms (PDE4A and PDE4D) increased in response to hypoxia in eight of the studied cell lines. Furthermore, we analyzed various in silico predicted hypoxia-responsive elements (p-HREs) found in in PDE4A and PDE4D genes. Performing mutation analysis of the p-HRE in luciferase reporter constructs, we identified four functional HRE sites in the PDE4A gene and two functional HRE sites in the PDE4D gene that mediated hypoxic induction of the reporter. Silencing of hypoxia-inducible factor subunits (HIF1alpha and HIF2alpha) by small interfering RNA reduced hypoxic induction of PDE4A and PDE4D. Vice versa, using a PDE4 inhibitor (PDE4i) as a cyclic adenosine monophosphate (cAMP) -elevating agent, cAMP analogs or protein kinase A (PKA)-modulating drugs and an exchange protein directly activated by cAMP (EPAC) activator, we demonstrated that PDE4-cAMP-PKA/EPAC axis enhanced HIF signaling as measured by HRE reporter gene assay, HIF and HIF target genes expression ((lactate dehydrogenase A), LDHA, (pyruvate dehydrogenase kinase 1) PDK1 and (vascular endothelial growth factor A) VEGFA). Notably, inhibition of PDE4 by PDE4i or silencing of PDE4A and PDE4D reduced human lung tumor cell proliferation and colony formation. On the other hand, overexpression of PDE4A or PDE4D increased human lung cancer proliferation. Moreover, PDE4i treatment reduced hypoxia-induced VEGF secretion in human cells. In vivo, PDE4i inhibited tumor xenograft growth in nude mice by attenuating proliferation and angiogenesis. Our findings suggest that PDE4 is expressed in lung cancer, crosstalks with HIF signaling and promotes lung cancer progression. Thus, PDE4 may represent a therapeutic target for lung cancer therapy.
Free Keywords:Animals; Basic Helix-Loop-Helix Transcription Factors/metabolism; Cell Line, Tumor; Cell Proliferation/drug effects; Cyclic AMP; Cyclic Nucleotide Phosphodiesterases, Type 3/metabolism; Cyclic Nucleotide Phosphodiesterases, Type 4/metabolism/*physiology; Humans; Hypoxia-Inducible Factor 1, alpha Subunit/*metabolism; Lung Neoplasms/*metabolism; Mice; Mice, Nude; Phosphodiesterase 4 Inhibitors/pharmacology; RNA, Small Interfering/pharmacology; Signal Transduction/drug effects; Transplantation, Heterologous
External Publication Status:published
Document Type:Article
Communicated by:Svea Hümmer
Affiliations:MPI für physiologische und klinische Forschung
Identifiers:ISSN:1476-5594 (Electronic) 0950-9232 (Linking) %R 10.1038/onc.2012.136
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