Regulation of HIF-1 α to expression of N-myc downstream regulated gene 1 in colorectal carcinoma

Plasmid expressing small interfering RNA (siRNA) against HIF-1a (pSilence-2.1-U6-siRNA) was constructed and transfected into LS174T cells in hypoxia condition. After expression of siRNA against HIF-1 α in LS174T cells, expressions of HIF-1 α and N-myc downstream regulated gene 1 (NDRG1) gene were inhibited significantly. HIF-1 α a transcripts were positive in 67.7% (42/62) and 44.4% (8/18) of colorectal adenocarcinoma and adenoma, respectively. The mean percentage of cells with positive hybridization of HIF-1 α mRNA increases with the development from Duke stage A to stage C+D (p < 0.05). The positive staining rate of NDRG1 protein was significant higher in colorectal adenocarcinoma group than that in colorectal adenoma group (p < 0.05). The level of HIF-1 α transcripts was positively correlated with the level of NDRG1 protein (p < 0.05) during colorectal tumor progression. HIF-1a and its down stream gene NDRG1 may play roles in tumor progression of human colorectal carcinoma.