The hTERT-VNTR2-2nd alleles are involved in genomic stability in gastrointestinal cancer

BackgroundhTERT contains a high density of minisatellites, of which rare alleles of hTERT-VNTR2-2(nd) have been reported to be associated with prostate cancer. This shows an association between VNTR and cancer, but this repeat sequence is likely to be associated with genomic instability. Therefore, we investigated the effects of hTERT-VNTR2-2(nd) on gastrointestinal cancer and the relationship between repeated sequence and chromosome instability.MethodsA case-control study was performed using DNA from 818 cancer-free controls, 539 cases with gastric cancer, 275 cases with colon cancer and 274 cases with rectal cancer. To determine whether minisatellites affect gene expression, expression levels were examined using TERT-reporter vectors in cell lines. In addition, the length of the hTERT-VNTR2-2(nd) alleles were determined in blood and cancer tissues from 107 gastric cancers, 112 colon cancers and 76 rectal cancers patients to determine whether the repeat sequence was associated with genomic instability during cancer development.ResultsNo statistically significant association between hTERT-VNTR2-2(nd) and risk of gastrointestinal cancer was detected. However, it has been shown that VNTRs inserted into the enhancer region can regulate the expression of TERT in gastrointestinal cancer cells. Moreover, hTERT-VNTR2-2(nd) was analyzed in matched blood and cancer tissue from patients with gastrointestinal cancer and in seven among 294 subjects, and hTERT-VNTR2-2(nd) was found to be rearranged.ConclusionsWe suggest that minisatellites are associated with genomic instability in cancer and that the hTERT-VNTRs region may increase hTERT expression in gastrointestinal cancer cells.