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Spectrophotometric Analyses of Cytochromes in Ascites Hepatomas of Rats and Mice

Department of Biochemistry, School of Medicine, Osaka University, Kita-ku, Osaka, Japan

The cytochrome contents in ascites hepatomas and some other fast-growing tumor cells of rats and mice were determined spectrophotometrically at room and low temperature and compared with those in normal liver cells. On a protein basis, the contents of cytochromes a(+ a₃), b, and c₁ in the various hepatomas are rather constant, and the levels are about one-half or one-third of those in normal livers. However, the content of cytochrome c is nearly equal to that in normal livers, and a high c/a(+ a₃) ratio has been observed in tumor cells. On a cell basis, the cytochrome concentrations in a tumor cell are much lower than those in a normal liver cell.

In tumor cells, a considerable amount of cytochrome b [and a part of cytochromes c and a(+ a₃)] could not be reduced immediately after anaerobiosis or by cyanide or sulfide treatment, indicating that these cytochromes are not linked to the electron transport chain. In normal liver cells all of the cytochromes, a(+ a₃), b, c, and c₁, are linked directly to the electron transport chain.

No cytochrome b₅ or P-450 was detected in the hepatomas and other tumor cells used, while hemoproteins 559 and 565 were present in these cells and their contents were nearly equal to those in normal livers.

¹ Present address: Johnson Research Foundation, School of Medicine, University of Pennsylvania, Philadelphia, Pa. 19104.

Received 11/12/69. Accepted 3/23/70.