engleski

Analysis of NF1 gene in sporadic colon cancer

Tumorigenesis of colon cancer is a multistep process of mutation accumulation in a number of oncogenes and tumor suppressor genes. NF1 protein product, neurofibromin, acts as a tumor suppressor by turning the active form of Ras into an inactive one. This molecular switch has an important role in the control of cell cycle and differentiation and the changes in the Ras activity are involved in number cancers. Several different isoforms are formed by alternative splicing of NF1 mRNA. Isoform type I was the first isolated isoform that lacks any insertions. Isoform type II contains an additional 63 bp insertion (exon 23a). These two isoforms are expressed at varying ratios in different cell types Several studies have shown that alterations in the type I vs. type II mRNA ratio can be associated with the development of certain malignancies. In this study we investigated the loss of heterozygosity (LOH) of the NF1 gene in 100 sporadic colon cancers. Quantitative RT-PCR was used to determine the NF1 mRNA expression in tumor and corresponding normal mucous tissue. Relative ratio of NF1 types I and II expression was examined as well. The results were correlated with the patients' clinicopathological features. LOH was observed in 20.7 % of informative samples. Expression of NF1 mRNA was higher in well differentiated tumors and tumors classified as Dukes' A. NF1 isoform type II was dominantly expressed in normal mucous tissue, while the isoform type I was dominantly expressed in tumor tissue.

NF1 gene expression; sporadic colon cancer

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