Original Article
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Jul 28, 2013; 19(28): 4486-4494
Published online Jul 28, 2013. doi: 10.3748/wjg.v19.i28.4486
Influence of up-regulation of Notch ligand DLL4 on biological behaviors of human gastric cancer cells
Guo-Gang Li, Lan Li, Chao Li, Long-Yun Ye, Xiao-Wen Li, Da-Ren Liu, Qi Bao, Yi-Xiong Zheng, Da-Peng Xiang, Li Chen, Jian Chen
Guo-Gang Li, Chao Li, Long-Yun Ye, Xiao-Wen Li, Da-Ren Liu, Qi Bao, Yi-Xiong Zheng, Da-Peng Xiang, Li Chen, Jian Chen, Department of Surgery, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China
Lan Li, Department of Gastroenterology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
Author contributions: Chen J designed the study; Li GG, Li C, Ye LY, Li XW, Liu DR, Bao Q, Zheng YX and Xiang DP carried out the study; Li GG, Chen L and Chen J analyzed the data; Li GG and Li L wrote the paper; all the authors contributed to the preparation of the manuscript.
Supported by The Key Project of Science and Technology of Zhejiang Province, No. 2009C14017; the National Natural Science Foundation of China, No. 81071959 and No. 81101837; the Zhejiang Provincial Medical and Healthy Science Foundation of China, No. 2013KYA100 and No. 2009B043; and the Public Welfare Technology Research Project of Zhejiang Province, No. 2010C34001
Correspondence to: Dr. Jian Chen, PhD, Department of Surgery, Second Affiliated Hospital, College of Medicine, Zhejiang University, No. 88 Jiefang Road, Hangzhou 310009, Zhejiang Province, China. chenjian_zju@163.com
Telephone: +86-571-87783582 Fax: +86-571-87022776
Received: April 18, 2013
Revised: June 11, 2013
Accepted: June 19, 2013
Published online: July 28, 2013
Processing time: 101 Days and 23.9 Hours
Abstract

AIM: To investigate the potential roles of Delta-like ligand 4 (DLL4) on the biological behavior of gastric cancer cells and its molecular mechanisms.

METHODS: A recombinant eukaryotic expression vector containing human DLL4 gene was constructed and transfected into the human gastric cancer cell line SGC7901. Clones with up-regulated DLL4 were selected and amplified. The effect of DLL4 up-regulation on gastric cancer cell growth was assessed using cell growth assay. The migration and invasion were assessed using a transwell migration assay and matrigel invasion assay. Matrix metalloproteinases were detected using the zymogram technique. Cells were implanted subcutaneously into male BALB/c nu/nu mice. Tumor volumes were then calculated and compared. DLL4 staining in the implanted tumor was performed using immunohistochemistry technique.

RESULTS: Growth curves over a six-day time course showed significantly promoted cell proliferation of SGC7901 cells with up-regulated DLL4. DLL4 up-regulation in SGC7901 cells promoted the migration (205.4 ± 15.2 vs 22.3 ± 12.1, P < 0.05) and invasion (68.8 ± 5.3 vs 18.2 ± 6.0, P < 0.05) in vitro and tumorigenicity in vivo (2640.5 ± 923.6 mm3vs 1115.1 ± 223.8 mm3, P < 0.05). Furthermore, significantly increased mRNA level and increased secretion of matrix metalloproteinase-2 (MMP-2) proenzyme were observed in SGC7901 cells with up-regulated DLL4. However, increased MMP-9 mRNA level but decreased extracellular MMP-9 proenzyme level was observed.

CONCLUSION: Our observations indicated a mechanism by which activation of DLL4-mediated Notch signaling promotes the expression and secretion of MMP-2 proenzyme and influences the progress of gastric cancer.

Keywords: Gastric cancer; Delta-like ligand 4/Notch; Matrix metalloproteinase; Migration; Invasion

Core tip: Delta-like ligand 4 (DLL4), one of the five notch signaling ligands in mammals, has been researched mainly with regard to vasculogenesis and tumor angiogenesis. To the best of our knowledge, there is rare study to investigate its role and mechanism in human gastric cancers. We found that DLL4 promotes cellular proliferation, migration, invasion and tumorigenicity in gastric cancer cells. Furthermore, increased mRNA level and increased secretion of matrix metalloproteinase-2 proenzyme, while increased matrix metalloproteinase (MMP)-9 mRNA levels but decreased extracellular MMP-9 proenzyme levels were observed. These results indicated a mechanism by which activation of DLL4-mediated Notch signaling promotes the expression and secretion of MMP-2 proenzyme and influences the progress of gastric cancer.