Research Article Differential Regulation of Gene Expression of Alveolar Epithelial Cell Markers in Human Lung Adenocarcinoma-Derived A549 Clones Hiroshi Kondo, 1,2 Keiko Miyoshi, 1 Shoji Sakiyama, 2 Akira Tangoku, 2 and Takafumi Noma 1 1 Department of Molecular Biology, Institute of Health Biosciences, he University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan 2 Department of horacic and Endocrine Surgery and Oncology, Institute of Health Biosciences, he University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan Correspondence should be addressed to Takafumi Noma; ntaka@tokushima-u.ac.jp Received 8 January 2015; Revised 10 April 2015; Accepted 21 April 2015 Academic Editor: Hannele T. Ruohola-Baker Copyright © 2015 Hiroshi Kondo et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Stem cell therapy appears to be promising for restoring damaged or irreparable lung tissue. However, establishing a simple and reproducible protocol for preparing lung progenitor populations is diicult because the molecular basis for alveolar epithelial cell diferentiation is not fully understood. We investigated an in vitro system to analyze the regulatory mechanisms of alveolus-speciic gene expression using a human alveolar epithelial type II (ATII) cell line, A549. Ater cloning A549 subpopulations, each clone was classiied into ive groups according to cell morphology and marker gene expression. Two clones (B7 and H12) were further analyzed. Under serum-free culture conditions, surfactant protein C (SPC), an ATII marker, was upregulated in both H12 and B7. Aquaporin 5 (AQP5), an ATI marker, was upregulated in H12 and signiicantly induced in B7. When the RAS/MAPK pathway was inhibited, SPC and thyroid transcription factor-1 (TTF-1) expression levels were enhanced. Ater treatment with dexamethasone (DEX), 8- bromoadenosine 3  5  -cyclic monophosphate (8-Br-cAMP), 3-isobutyl-1-methylxanthine (IBMX), and keratinocyte growth factor (KGF), surfactant protein B and TTF-1 expression levels were enhanced. We found that A549-derived clones have plasticity in gene expression of alveolar epithelial diferentiation markers and could be useful in studying ATII maintenance and diferentiation. 1. Introduction Lung diseases such as chronic obstructive pulmonary disease and idiopathic pulmonary ibrosis can be life threatening. Until now, lung transplantation has been the treatment of choice for the severe cases [1]. However, lung trans- plantation is associated with several problems, including issues with histocompatibility and a shortage of donors. herefore, regenerative medicine of the lungs using stem cells is attracting a lot of attention as a promising therapy [2, 3]. Recently, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have been used to study the possible regeneration of alveolar epithelial type (AT) cells [4, 5]. Diferentiation into AT cells from ESCs and iPSCs still needs to pass through the several developmental stages, and the regulation of this developmental process remains unclear. hus, it is required to establish a simple and reproducible model system to understand the molecular basis of the diferentiation of divergent progenitor populations in the human lung and to further develop lung regenerative therapy. Lung alveoli, which are essential for respiratory function, are composed of two types of alveolar epithelial cells, that is, type I (ATI) and type II (ATII). ATI cells are lat cells that cover 95% of alveoli, and they are involved in the exchange oxygen and carbon dioxide [6, 7]. hese cells express speciic diferentiation markers, such as aquaporin 5 (AQP5 [8, 9]), caveolin-1 [10], and the receptor for advanced glycation end products [11]. ATII cells are cuboidal cells and produce surfactant, which consists of proteins such as surfactant proteins A, B, C, and D (SPA, SPB, SPC, and SPD), and phospholipids. hese surfactants are essential for maintenance of alveoli and host defense [12–14]. SPA, SPB, Hindawi Publishing Corporation Stem Cells International Volume 2015, Article ID 165867, 20 pages http://dx.doi.org/10.1155/2015/165867