A new cell line derived from a woodchuck hepatocellular carcinoma serially transplanted in athymic nude mice has been established and named WH257GE10. The original tumor in the nude mouse system produces woodchuck hepatitis surface antigen and albumin. In addition, woodchuck hepatitis virus DNA is integrated into cellular DNA. Adaptation of the cells to the in vitro culture condition was completed after 15 months with the doubling time of 40 hr. The morphologic features of the cell by light microscopy are of an epithelial type. The modal chromosome number is 36 and the karyotype is mainly metacentric, similar to that observed in normal woodchuck liver cells. Ornithine and tyrosine aminotransferase activities were detected. Production of albumin was demonstrated in the cytoplasm by indirect immunofluorescence. Integration of woodchuck hepatitis virus DNA was shown by Southern blot analysis, although the secretion of woodchuck hepatitis surface antigen was not detected. This cell line provides an excellent in vitro model to study human hepatocellular carcinoma related to hepatitis B virus.
Woodchuck hepatitis virus (WHV), one of the four hepadna viruses (l), is very closely related to woodchuck hepatocellular carcinoma (HCC). HCC usually develops in animals positive for woodchuck hepatitis surface antigen (WHsAg) (2). There is no difference in sex nor apparent influences by aflatoxin, and cirrhosis is absent (3). In contrast, development of HCC is very rare in WHsAg-negative animals.
Because of the structural homology between WHV and hepatitis B virus (HBV) DNA, woodchuck HCC may provide important clues in understanding the oncogenicity of HBV. In a previous report (4), we described the establishment of a woodchuck HCC tumor in the nude mouse. The tumor has been transplanted for more than 10 passages. This paper reports the establishment and characterization of a continuously growing cell line of woodchuck HCC derived from the serially transplanted tumor in nude mice.