Association between CYP24A1 polymorphisms and the risk of colonic polyps and colon cancer in a Chinese population

AIM To determine the pathogenesis and potential single nucleotide polymorphisms(SNPs) as screening sites for colonic polyps,colon cancer and ulcerative colitis,and to analyze the possible association between these genetic polymorphisms and the three diseases. METHODS We evaluated genetic polymorphisms in 144 newly diagnosed colonic polyp patients,96 colon cancer patients and 44 ulcerative colitis patients. The four SNPs genotyped were rs4809957,rs6068816,rs6091822 and rs8124792. The control group consisted of 504 East Asians enrolled in the 1000 Genomes Project. Correlations between CYP24A1 SNPs and the diseases were analyzed by Fisher's exact probability test.RESULTS CYP24A1 polymorphisms rs4809957 A/G and rs6068816 C/T showed a statistically significant association with risk of the three diseases,when both the genotypes and allele frequencies were considered. With regard to rs6091822 G/T,all three diseases were related to risk allele carriers(GT + TT) vs wild-type(GG),but the associations between the allele frequencies and the diseases were not significant. The risk of colonic polyps and colon cancer was related to the allele frequencies of rs8124792 G/A,and this association remained for genotype frequencies of this SNP. CONCLUSION Four SNPs are related to the risk of colonic polyps and colon cancer. G allele in rs6091822 G/T may play an anti-cancer role only if it is homozygous. The A allele,which is a minor component of rs8124792,may be indicated in the diagnosis of colonic polyps or colon cancer rather than ulcerative colitis.

CYP24A1 Involvement in Inflammatory Factor Regulation Occurs via the Wnt Signaling Pathway

Objective While the upregulation of cytochrome P450 family 24 subfamily A member 1(CYP24A1)gene expression has been reported in colon cancer,its role in tumorigenesis remains largely unknown.In this study,we aimed to investigate the involvement of CYP24A1 in Wnt pathway regulation via the nuclear factor kappa B(NF-κB)pathway.Methods The human colon cancer cell lines HCT-116 and Caco-2 were subjected to stimulation with interleukin-6(IL-6)as well as tumor necrosis factor alpha(TNF-α),with subsequent treatment using the NF-κB pathway-specific inhibitor ammonium pyrrolidinedithiocarbamate(PDTC).Furthermore,CYP24A1 expression was subjected to knockdown via the use of small interfering RNA(siRNA).Subsequently,NF-κB pathway activation was determined by an electrophoretic mobility shift assay,and the transcriptional activity ofβ-catenin was determined by a dual-luciferase reporter assay.A mouse ulcerative colitis(UC)-associated carcinogenesis model was established,wherein TNF-αand the NF-κB pathway were blocked by anti-TNF-αmonoclonal antibody and NF-κB antisense oligonucleotides,respectively.Then the tumor size and protein level of CYP24A1 were determined.Results IL-6 and TNF-αupregulated CYP24A1 expression and activated the NF-κB pathway in colon cancer cells.PDTC significantly inhibited this increase in CYP24A1 expression.Additionally,knockdown of CYP24A1 expression by siRNA could partially antagonize Wnt pathway activation.Upregulated CYP24A1 expression was observed in the colonic epithelial cells of UC-associated carcinoma mouse models.Anti-TNF-αmonoclonal antibody and NF-κB antisense oligonucleotides decreased the tumor size and suppressed CYP24A1 expression.Conclusion Taken together,this study suggests that inflammatory factors may increase CYP24A1 expression via NF-κB pathway activation,which in turn stimulates Wnt signaling.