The biochemistry of preneoplastic liver: a common metabolic pattern in hepatocyte nodules.

The biochemical properties of putative preneoplastic hepatocyte nodules as they relate to the metabolism of xenobiotics have been reviewed briefly. A common pattern with low phase I components and elevated phase II components appears evident. The phase I components included microsomal cytochromes P-450 in composite and four different mixed function oxygenase activities. The activities in the nodules were 50% or less of the control values. The phase II components included glutathione, glutathione S-transferases and UDP-glucuronyl transferase 1 and showed two- to five-fold elevations. In addition, activities of microsomal epoxide hydrolase, cytosolic DT-diaphorase, and gamma-glutamyl transferase were all elevated in nodules. The possible significance of this biochemical pattern in analyzing the diversity of biochemical expressions of cancer, in the mechanism of cancer development, and in understanding the suggested role of physiological adaptation in carcinogenesis is discussed.