Loss of heterozygosity on hromosome 1 in sporadic colorectal carcinoma

AIM: Loss of heterozygosity (LOH) on tumor suppressorgenes is believed to play a key role in carcinogenesis ofcolorectal cancer.When it occurs at a tumor suppressorgene locus with abnormal allele,neoplastic transformationhappens.In this study,we analyzed the LOH at 21 loci onchromosome 1 in sporadic colorectal cancer to identifyadditional loci involved in colorectal tumorigenesis.METHODS: Twenty-one polymorphic micro-satellite DNAmarkers were analyzed with PCR both in 83 cases ofcolorectal cancer and in normal tissues.PCR products wereeletrophoresed on an ABI 377 DNA sequencer.Genescan3.1 and Genotype 2.1 software were used for LOH scanningand analysis.χ~2 test was used to compare LOH frequencywith clinicopathological data.P<0.05 was considered asstatistically significant.RESULTS: The average LOH frequency of chromosome 1,short arm and long arm was 19.83%,18.00% and 21.66%,respectively.The 2 highest LOH loci with a frequency of36.54% and 32.50% were identified on DIS468 (1p36.33-p36.31) and DIS413 (1q31.3),respectively.On DIS2726locus,LOH frequency of rectal cancer was 28.57% (6/21),which was higher than that of colon cancer (0.00%,0/33)(P=0.002),suggesting that the mechanism of carcinogenisiswas different in both groups.CONCLUSION: Putative tumor suppressor genes onchromosome 1 may relate to sporadic colorectal carcinomas.Tumor-suppressor-genes might locate on 1p36.33-36.31and/or 1q31.3.