Conditioned media from lung cancer cell line A549 and PC9 inactivate pulmonary fibroblasts by regulating protein phosphorylation.
Pulmonary fibrosis is a devastating condition resulting from excess extracellular matrix deposition that leads to progressive lung destruction and scarring. In the pathogenesis of fibrotic diseases, activation of myofibroblasts by transforming growth factor-β (TGF-β) plays a crucial role. Since no effective therapy for pulmonary fibrosis is currently recognized, finding an effective antifibrotic agent is an important objective. One approach might be through identification of agents that inactivate myofibroblasts. In the current study we examined the potential of conditioned medium obtained from several types of cells to exhibit myofibroblast inactivating activity. Conditioned media from lung cancer cell lines A549 and PC9 were found to have this action, as shown by its ability to decrease α-smooth muscle actin expression in MRC-5 cells. Subsequently the inhibitory factor was purified from the medium and identified as 5'-deoxy-5'-methylthioadenosine (MTA), and its mechanism of action elucidated. Activation of protein kinase A and cAMP responsive element binding protein (CREB) were detected. MTA inhibited TGF-β-induced mitogen-activated protein kinase activation. Furthermore, the gain-of-function mutant CREB caused inactivation of myofibroblasts. These results show that A549 and PC9 conditioned media have the ability to inactivate myofibroblasts, and that CREB-phosphorylation plays a central role in this process.
Department of Biochemistry, Kinki University, Ohno-Higashi, Osaka-Sayama, Osaka, Japan.
Ah-Mee
AM
Park
Sumio
S
Hayakawa
Eiko
E
Honda
Yoshihiro
Y
Mine
Koji
K
Yoshida
Hiroshi
H
Munakata
D000199:Actins; D000818:Animals; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000494:pharmacology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003839:Deoxyadenosines / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D008175:Lung Neoplasms / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D013872:Thionucleosides / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000378:metabolism
D000199:Actins; C115163:CREB1 protein, human; D017077:Culture Media, Conditioned; D017362:Cyclic AMP Response Element-Binding Protein; D003839:Deoxyadenosines; D004791:Enzyme Inhibitors; D013872:Thionucleosides; D016212:Transforming Growth Factor beta; C008500:5'-methylthioadenosine; D017868:Cyclic AMP-Dependent Protein Kinases