Up-Regulation of pVHL along with Down-Regulation of HIF-l alpha by NDRG2 Expression Attenuates Proliferation and Invasion in Renal Cancer Cells
PLOS ONE
Authors: Gao, Lei; Wu, Guo-jun; Liu, Bei; Shen, Ming-zhi; Pan, Tie-jun; Yu, Chui-gong; Wang, Qin-hao; Ru, Yi; Liu, Xi-ping; Niu, Tian-shui; Wang, Guo-dong; Wei, Ming; Li, Rui-xiao; Yao, Libo; Wang, He; Li, Xia
Abstract
The majority of renal cell carcinomas (RCCs) are characterized by loss of function of he tumor suppressor gene von Hippel Lindau (VHL), which acts as ubiquitin ligase for hypoxia-inducible factor-l alpha (HIF-1 alpha). In the absence of VHL, HIF-l alpha Protein becomes stabilized and contributes to tumorigenesis. Recent data demonstrate the antitumor efficacy of VHL promoter in RCC cells. This study demonstrates that N-Myc downstream-regulated gene 2 (NDFRG2) is a potential regulator of VHL. NDRG2 is involved in proliferation and invasion of cancer cell, furthermore it is frequently down-regulated in renal cell carcinoma. Herein we evaluated the effect of NDRG2 overexpression on proliferation and invasion in human renal cancer cells. The human renal cancer cell line 786-O and A498 were infected with Ad-NDRG2 or Ad-LacZ. Overexpression of NDRG2 not only inhibited the growth of the cells, but also suppressed the invasion. Further study showed that the tumor suppressor gene VHL were up-regulated, whereas transcription factor HIF-1a and vascular endothelial growth factor (VEGF) were down-regulated in 786-O cells infected by Ad-NDRG2. Finally, in a nude mouse model, intratumoral injections of Ad-NDRG2 every 3 days for a total of seven times significantly inhibited the growth and angiogenesis of xenografted 786-O tumors. In conclusion, these data indicate that NDRG2 may be involved in proliferation and invasion by impacting the expression of VHL and HIF-l alpha. NDRG2 may be an attractive therapeutic target for renal cell carcinoma.
NDRG2, suppressed expression associates with poor prognosis in pancreatic cancer, is hypermethylated in the second promoter in human gastrointestinal cancers
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Authors: Yamamura, Akihiro; Miura, Koh; Karasawa, Hideaki; Motoi, Fuyuhiko; Mizuguchi, Yasuhiko; Saiki, Yuriko; Fukushige, Shinichi; Sunamura, Makoto; Shibata, Chikashi; Unno, Michiaki; Horii, Akira
Abstract
Although N-myc downstream regulated gene 2 (NDRG2) is frequently downregulated in various cancers and is considered to be a candidate tumor suppressor gene, molecular mechanisms of the expressional suppression that lead to cancers are largely unknown. Recent studies indicated that epigenetic suppression of NDRG2 involved carcinogenesis and progression in several tumor types, and we demonstrated positive association with NDRG2 suppression and poor prognosis in pancreatic cancer. In this study, we analyzed mRNA and protein expressions of NDRG2 in 26 cancer cell lines (20 colorectal and 6 gastric cancers) and found that many cell lines showed variously reduced NDRG2 expressions. Furthermore, NDRG2 expressions were significantly reduced in primary resected cancer tissues compared to corresponding normal tissues immunohistochemically (19 of 20 colorectal and 14 of 17 gastric cancers).Treatment with 5-Aza-2' deoxycytidine predominantly upregulated NDRG2 expressions in NDRG2 low-expressing cell lines. Bisulfite sequencing analyses and methylation specific PCR revealed that methylation status at one of the two promoters (around exon 2) correlated well with the suppressed expression, and this is the major promoter in colorectal and gastric cancer cell lines. Our present results suggest that hypermethylation in promoter around exon 2 is functioning as essential factors of NDRG2 silencing in gastrointestinal cancers. (C) 2017 Elsevier Inc. All rights reserved.