Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Mar 14, 2012; 18(10): 1028-1037
Published online Mar 14, 2012. doi: 10.3748/wjg.v18.i10.1028
15-PGDH is reduced and induces apoptosis and cell cycle arrest in gastric carcinoma
Li-Hong Lou, Da-Dao Jing, Yue-Xing Lai, Ying-Ying Lu, Ji-Kun Li, Kai Wu
Li-Hong Lou, International Medical Care Center, Shanghai First People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200080, China
Da-Dao Jing, Yue-Xing Lai, Ying-Ying Lu, Kai Wu, Department of Gastroenterology, Shanghai First People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200080, China
Ji-Kun Li, Department of Surgery, Shanghai First People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200080, China
Author contributions: Lou LH and Jing DD contributed equally to this work; Lou LH and Jing DD designed the research; Lou LH, Lai YX and Lu YY performed the research; Li JK supplied gastric cancer specimens; Wu K contributed new reagents and analytic tools; Lou LH analyzed the data; Lou LH and Jing DD wrote the paper.
Supported by Shanghai Science and Technology Commission Foundation, No. 06BZ066
Correspondence to: Da-Dao Jing, MD, Professor of Medicine, Department of Gastroenterology, Shanghai First People’s Hospital, School of Medicine, Shanghai Jiao Tong University, 100 Haining Road, Hongkou District, Shanghai 200080, China. jingdadao@medmail.com.cn
Telephone: +86-21-63240090-2214 Fax: +86-21-63069484
Received: August 8, 2011
Revised: January 16, 2012
Accepted: February 8, 2012
Published online: March 14, 2012
Abstract

AIM: To investigate the expression of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in human gastric cancer and it’s mechanism in apoptosis and cell cycle arrest.

METHODS: Expression of 15-PGDH mRNA and protein was examined by immunohistochemistry, immunocytochemistry, reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting in tissue from human gastric cancer, gastric precancerous state (gastric polyps and atrophic gastritis), normal stomach, and gastric cancer cell lines. The relationship between gastric cancer, gastric precancerous state and 15-PGDH expression was determined. The association between expression of 15-PGDH and various clinicopathological parameters in gastric cancer was evaluated. Human gastric cancer cell line SGC-7901 was transfected with 15-PGDH expression plasmids. The effect of 15-PGDH on the cell cycle was examined by flow cytometry. The effect of 15-PGDH on apoptosis was examined by transmission electron microscopy, flow cytometry and transferase mediated nick end labeling (TUNEL) assay. Expression of cell cycle (p21, p27, p16 and p53) and apoptosis (Survivin, BCL-2, BCL-XL, BAK and BAX) genes was analyzed by RT-PCR.

RESULTS: Expression of 15-PGDH mRNA and protein in human gastric cancer tissues was significantly lower than in normal gastric tissues (P < 0.01). Expression in human gastric cancer cell lines MKN-28 and MKN-45 was reduced, and absent in SGC-7901 cells (P < 0.05). Reduction of 15-PGDH expression was also found in precancerous tissues, such as gastric polyps and atrophic gastritis (P < 0.01). There was a significant difference in expression of 15-PGDH among various gastric cancer pathological types (P < 0.05), with or without distant metastasis (P < 0.05) and different TNM stage (P < 0.01). Flow cytometry demonstrated a significant increase in apoptotic cells in SGC-7901 cells transfected with pcDNA3/15-PGDH plasmid for 24 h and 48 h (P < 0.01), and an increased fraction of sub-G1 phase after transfection (P < 0.05). TUNEL assay showed an increased apoptotic index in cells overexpressing 15-PGDH (P < 0.01). After transfection, expression of proapoptotic genes, such as BAK (P < 0.05), BAX and p53 (P < 0.01), was increased. Expression of antiapoptotic genes was decreased, such as Survivin, BCL-2 and BCL-XL (P < 0.01). Expression of cyclin-dependent kinase inhibitors p21 and p16 (P < 0.01) was significantly upregulated in cells overexpressing 15-PGDH.

CONCLUSION: Reduction of 15-PGDH is associated with carcinogenesis and development of gastric carcinoma. 15-PGDH induces apoptosis and cell cycle arrest in SGC-7901 cells.

Keywords: Gastric carcinoma; 15-hydroxyprostaglandin dehydrogenase; Apoptosis; Cell cycle arrest; Tumor growth