Loss of imprinting of long QT intronic transcript 1 in colorectal cancer

Loss of imprinting (LOI) of the insulin-like growth factor 2 (IGF2) and H19 genes on human chromosome 11 has been found not only in childhood tumors b ut also in common adult cancers including colorectal cancer. Recently, a tr anscript called LIT1 (long QT intronic transcript 1) has been identified wi thin the KvLQT1 locus on chromosome 11. LIT1 is expressed preferentially fr om the paternal allele and is transcribed in most human tissues. LOI of LIT 1 was found in a considerable number of Beck-with-Wiedemann syndrome (BWS) patients, suggesting that it is associated with the etiology of BWS. Since LOI of IGF2 was observed in association with overexpression of IGF2 in colo rectal cancer in our previous study, we examined the status of genomic impr inting of LIT1 and H19 in comparison with IGF2 in colorectal cancer. We exa mined 44 surgically dissected colorectal cancer tissues, Ten of them repres ented informative cases for LIT1. None of these patients exhibited loss of heterozygosity (LOH) of LIT1, and LOI of LIT1 was observed in 4 of the 10 ( 40%) informative patients, but not in non-cancerous tissues. Neither LOH no r LOI of H19 was observed. LOI of IGF2 was observed in 4 of 18(22%) informa tive patients. These results suggest that LOI of LIT1 is frequently observe d in colorectal cancer and may be a useful marker for diagnosis of colorect al cancer. Copyright (C) 2001 S. Karger AG, Basel.