期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1981
卷号：78
期号：2
页码：834-837
DOI：10.1073/pnas.78.2.834
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：When liver cells undergo malignant transformation, certain genes cease being expressed. We have studied the structure of one such gene, whose protein product we have designated hepatic protein 22 (hp22), which is not expressed in the two Morris hepatomas studied. We have prepared a chimeric clone of pBR322 containing cDNA sequences complementary to mRNA coding for this protein. By using this cloned cDNA, we have examined changes in expression of this gene and changes in the restriction pattern of the DNA isolated from normal liver and these hepatomas. In both hepatomas, studies using the isoschizomeric pair of restriction enzymes Msp I and Hpa II have indicated hypermethylation of a cytosine residue within or proximal to the hp22 gene. Other differences in the restriction pattern between normal liver and hepatoma DNA were also detected with EcoRI and Ava I. Thus, in the nontranscribed form of this gene, the DNA has undergone covalent modification, distinguishing these two hepatomas from each other and from normal liver.
