Gene expression during multistage hepatocarcinogenesis

Several multistage models of hepatocarcinogenesis in the rat have now been developed. In one of these models at least three distinct stages--initiation, promotion, and progression--can be delineated. The first and last are irreversible, while that of promotion is reversible. Quantitation of each stage is possible. While several variable marker enzymes have been utilized to identify and characterize preneoplastic lesions during the stage of promotion, preliminary investigations indicate that the transcriptional activation of proto-oncogenes, particularly that of c-raf-1 proto-oncogene, may be used as an indicator of those preneoplastic lesions that will potentially develop into malignant neoplasms.