Single nucleotide polymorphisms in the CDH17 gene of colorectal carcinoma

Abstract

Aim: To investigate the relationship between c.343A>G and c.2216A>C polymorphism sites in the CDH17 gene and colorectal carcinoma.

Methods: Ninety-three non-consanguineous colorectal carcinoma patients admitted to the Department of Oncology at the First Affiliated Hospital of Zhengzhou University were included in this study. Ninety-three peripheral venous blood samples, of approximately one milliliter from each patient, were collected between December 2009 and August 2010. The genomic DNA of these peripheral venous blood samples were extracted and purified using a Fermentas Genomic DNA Purification Kit (Fermentas, CA) according to the manufacturer's protocol. The single nucleotide polymorphisms (SNPs) of the liver-intestine cadherin (CDH17) gene c.343A>G and c.2216A>C were determined by the polymerase chain reaction-single strand conformation polymorphism method (PCR-SSCP) in 93 peripheral venous blood samples from patients suffering with colorectal carcinoma. Typical samples that showed different migration bands in SSCP were confirmed by sequencing. Directed DNA sequencing was used to check the correctness of the genotype results from the PCR-SSCP method.

Results: There was a significant association between the c.2216 A>C SNPs of the CDH17 gene and the tumor-node-metastasis (TNM) grade, as well as with lymph node status, in 93 peripheral venous blood samples from colorectal carcinoma patients. The genotype frequencies of A/C, A/A, and C/C were 12.90%, 33.33% and 53.76%, respectively. There was a significant correlation between lymph node metastasis, TNM grade, and the genotype distribution (P < 0.05). The C/C genotype raised the risk of lymph node metastasis and the TNM grade. There was a significant difference in the TNM grade and lymph node metastasis between the A/A and C/C genotypes (P = 0.003 and P = 0.013, respectively). Patients with colorectal carcinoma carrying the C allele tended to have a higher risk of lymph node metastasis and have a higher TNM grade. The difference between the TNM grades, as well as the lymph node metastasis of the two alleles, was statistically significant (P < 0.01).

Conclusion: The SNPs of the CDH17 gene c.2216 A>C might be clinically important in the prognosis of colorectal carcinoma.

Keywords: Colorectal carcinoma; Liver-intestine cadherin; Polymerase chain reaction-single strand conformation polymorphism method; Single nucleotide polymorphisms.

Figure 2

The sequence results of CDH17 gene c.343A>G (A) and CDH17 gene c.2216A>C (B). A: The upper homozygous genotype (A/A); The middle heterozygous genotype (A/G); The lower homozygous genotype (G/G); Arrow head: Point mutations of CDH17 gene c.343A>G; B: The upper homozygous genotype (A/A); The middle heterozygous genotype (A/C); The lower homozygous genotype (C/C); Arrow head: Point mutations of CDH17 gene c.2216A>C.

Figure 1

Polymerase chain reaction amplification of CDH17 gene c.343A>G (the upper) and c.2216A>C (the lower) from genomic DNA of colorectal carcinoma. Lane M: Marker; Lane 1-6: Samples.