Insulin‐like growth factor 2 hypomethylation of blood leukocyte DNA is associated with gastric cancer risk

Abstract

To determine whether or not the methylation status of blood leukocyte DNA can be used as a surrogate marker of the risk for cancer, we quantitatively determined the methylation levels of insulin-like growth factor 2 (IGF2) and TUSC3 in 299 gastric cancer cases, and 299 age-and gender-matched controls. The IGF2 methylation levels in blood leukocyte DNA of the cases were lower than those of the healthy controls and there was a significant trend of increasing gastric cancer risk with decreasing methylation level of IGF2. Patients with hypermethylated IGF2 in blood leukocyte DNA showed a significantly better survival rate than those with hypomethylated IGF2, indicating that the IGF2 methylation level in blood leukocyte DNA can be a possible marker not only of the risk for but also of the prognosis of gastric cancer. In contrast, the TUSC3 methylation level in blood leukocyte DNA was higher in the cases than in the healthy controls, but the difference was not significant. The past lifestyle and clinicopathological characteristics of the participants were analyzed for any relationship with the methylation level. With aging and smoking, methylation of IGF2 and TUSC3 decreased and increased in blood leukocyte DNA, respectively. These results indicate that the methylation level of IGF2 in blood leukocyte DNA may be used as an important surrogate marker of the risk for gastric cancer.

Methylation Status of Blood Leukocyte DNA and Risk of Gastric Cancer in a High-Risk Chinese Population

“…Bisulfite-treated DNA was then purified with a genomic DNA purification kit (Promega). Quantitative methylation-specific PCR was carried out for IGFII and N33 using a 7500 fast Real-Time PCR System (Applied Biosystems) with the primers and probes as described previously (17). The PCR amplification was performed with a final reaction mixture of 20 mL consisting of 1Â TaqMan Fast Universal PCR Master Mix (Applied Biosystems), 0.9 mmol/L each of forward and reverse primers, 0.25 mmol/L each of probes, and 20 ng of DNA at the following conditions: 95 C for 20 seconds, followed by 40 cycles at 95 C for 3 seconds, and 61 C for 1 minute for IGFII (60 C for 30 seconds for N33).…”

“…The DNA of MKN74 cell line was kindly provided by Prof. Dajun Deng at Peking University Cancer Hospital and Institute (Beijing, China; ref. 26), and was confirmed to be 100% methylated in the CpGs in IGFII and N33 probes (17). The analysis was performed blind by one technician, and various lesion groups were randomly mixed for bisulfite treatment and real-time PCR.…”

“…The hypomethylation of IGFII promoter may be one of the critical mechanisms in LOI-mediated IGFII overexpression (16). Therefore, the methylation level of IGFII in blood leukocyte DNA may serve as a surrogate marker for the risk and prognosis of gastric cancer (17).…”

“…As a putative tumor suppressor gene, hypermethylated N33 was found in colorectal cancer, and was age-related in normal colorectal mucosa (19). The presence of Helicobacter pylori (H. pylori), an important risk factor of gastric cancer, showed a significant association with a higher methylation level of N33 in blood leukocyte DNA (17).…”

Tumor Suppressor Candidate TUSC3 Expression during Rat Testis Maturation

“…We used DNA microarray analysis for overall screening of the genes in the developing testis, focusing on cancer suppressors, and analyzed one candidate, tumor suppressor candidate gene 3 (Tusc3), because histological analysis of the gene product in the developing testis section is not yet clarified. Tusc3 gene expression has been analyzed in prostate cancer, [9][10][11][12] ovarian cancer, [13][14][15] gastric cancer, 16) osteosarcoma, 17) and pancreatic adenocarcinoma. [18][19][20] High-density screening of human prostate, lung, liver, and colon tumor cell lines has revealed homozygous deletions spanning the entire short arm of chromosome 8, which includes the Tusc3 gene.…”