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// Seung-Hyun Hong 1,* , Sung-Ho Goh 2,* , Sang Jin Lee 3 , Jung-Ah Hwang 1 , Jieun Lee 1 , Il-Ju Choi 4 , Hyehyun Seo 3 , Jong-Hoon Park 6 , Hiromu Suzuki 7 , Eiichiro Yamamoto 7 , In-Hoo Kim 5 , Jin Sook Jeong 8 , Mi Ha Ju 8 , Dong-Hee Lee 9 , and Yeon-Su Lee 1 1 Cancer Genomics Branch, Research Institute, National Cancer Center, Republic of Korea, 2 New Experimental Therapeutics Branch, Research Institute, National Cancer Center, Republic of Korea, 3 Genitourinary Cancer Branch, Research Institute, National Cancer Center, Republic of Korea, 4 Center for Gastric Cancer, Research Institute, National Cancer Center, Republic of Korea, 5 Molecular Imaging and Therapy Branch, Research Institute, National Cancer Center, Republic of Korea, 6 Department of Biological Science, Sookmyung Women’s University, Seoul, Republic of Korea, 7 Department of Molecular Biology, Sapporo Medical University, Sapporo, Japan, 8 Department of Pathology, Dong-A University College of Medicine, Busan, Republic of Korea, 9 Department of Life Science, Ewha Woman’s University, Seoul, Republic of Korea * These two authors contributed equally to this work. Correspondence: Yeon-Su Lee, email: // Dong-Hee Lee, email: // Keywords : gastric cancer, adenylate cyclase, tumorigenesis, cAMP/PKA/CREB pathway, promoter methylation Received : August 23, 2013 Accepted : September 28, 2013 Published : September 30, 2013 Abstract Adenylate cyclase 3 ( ADCY3 ) is a widely expressed membrane-associated protein in human tissues, which catalyzes the formation of cyclic adenosine-3′,5′-monophosphate (cAMP). However, our transcriptome analysis of gastric cancer tissue samples (NCBI GEO GSE30727) revealed that ADCY3 expression was specifically altered in cancer samples. Here we investigated the tumor-promoting effects of ADCY3 overexpression and confirmed a significant correlation between the upregulation of ADCY3 and Lauren’s intestinal-type gastric cancers. ADCY3 overexpression increased cell migration, invasion, proliferation, and clonogenicity in HEK293 cells; conversely, silencing ADCY3 expression in SNU-216 cells reduced these phenotypes. Interestingly, ADCY3 overexpression increased both the mRNA level and activity of matrix metalloproteinase 2 ( MMP2 ) and MMP9 by increasing the levels of cAMP and phosphorylated cAMP-responsive element-binding protein (CREB). Consistent with these findings, treatment with a protein kinase A (PKA) inhibitor decreased MMP2 and MMP9 expression levels in ADCY3 -overexpressing cells. Knockdown of ADCY3 expression by stable shRNA in human gastric cancer cells suppressed tumor growth in a tumor xenograft model. Thus, ADCY3 overexpression may exert its tumor-promoting effects via the cAMP/PKA/CREB pathway. Additionally, bisulfite sequencing of the ADCY3 promoter region revealed that gene expression was reduced by hypermethylation of CpG sites, and increased by 5-Aza-2′-deoxycytidine (5-Aza-dC)-induced demethylation. Our study is the first to report an association of ADCY3 with gastric cancer as well as its tumorigenic potentials. In addition, we demonstrate that the expression of ADCY3 is regulated through an epigenetic mechanism. Further study on the mechanism of ADCY3 in tumorigenesis will provide the basis as a new molecular target of gastric cancer.