The Partial CDNA Clone Of A Novel Gene Expressed At High Level In Hepatocellular Carcinoma

We applied the technique of Northern blot analysis to isolate from EST (expressed sequence tags) clones a cDNA fragment differentially expressed in normal liver tissue versus hepatocellular carcinoma. Further screening of human fetal liver cDNA library with this EST fragment probe, we obtained 12 positive colnes. The longest one which could represent these clones named FL6 contained 1464 base pairs. Nucleotide sequencing indicated that FL6 was part of a novel gene that had not included in the Gene Databses (EMAL, 96. 4). Northern blot analysis of various fetus tissues with FL6 probe showed high level expression in lung, small intestine, skin and placenta, middle level expression in liver, stomach ,colon and muscle, but low level expression in brain, thyroid, thy-mus, heart, kidney, pancreas and bladder. Northern blot analysis also showed that FL6 expressed at high level in all the 6 hepatocellular carcinoma samples but low level or no expression in the surrounding noncancerous hepatic tissue of the same samples and 2 normal liver tissues, No difference was found between hepatocellular carcinoma and surrounding noncancerous hepatic tissue with Southern blot analysis. The results suggested that FL6 gene ralated to cell growth and differentiation and might play an important role in the process of oncogenesis. The further cloning of the full lenth cDNA of this novel gene is now in progress.