Relationship between LAPTM4B gene polymorphism and susceptibility of colorectal and esophageal cancers.

Background: Lysosome-associated protein transmembrane 4 beta (LAPTM4B) is a novel gene of the mammalian LAPTM family and has been shown to be overexpressed in human hepatocellular carcinoma. There are two alleles, L4PTM4B*1 and *2, which share the same sequence except for one segment of 19 bp in the 5' untranslated region of the exon 1. LAPTM4B*1 has one 19 bp segment, while LAPTM4B*2 has two tight tandem segments. The current case-control study was aimed to identify relationship between the gene polymorphism of LAPTM4B and the susceptibility of colorectal and esophageal cancers. Patients and methods: Blood samples were collected from patients with colon, rectal or esophageal cancers and control subjects. Genotypes of LAPTM4B were determined by PCR to detect differences between cancer cases (n = 701) and healthy controls (n = 350). Association between the LAPTM4B polymorphism and the risk of cancer was calculated by unconditional logistic regression models. Results: We found that there was a significant difference (P = 0.0016) in allelic frequencies of LAPTM4B*2 between colon cancer cases (33.2%) and controls (24.1%). The risk of colon cancer was elevated significantly in cases with *1/2 genotype [odds ratio (OR) = 1.474; 95% confidence interval (Cl) = 1.037-2.095] and *2/2 genotype (OR = 2.531; 95% Cl = 1.316-4.868) when compared with the *1/1 genotype. No significant difference was observed for LAPTM4B*2 between the rectal or esophageal cancer cases when compared with the controls. The polymorphism in LAPTM4B was associated with increased risk of colon cancer but not of rectal and esophageal cancers. Conclusions: These results indicate that the genetic polymorphism of LAPTM4B is a potential risk factor for the development of colon cancer.