The microsome of tumor tissues and their surrounding nontumor tissues of five HCC were prepared with a differential centrifugation procedure. The proteins in cytosol and microsome were separated with the thin layer isoelectric focusing (IEF). The contents of zinc (Zn)

iron (Fe)

copper (Cu)

and manganese (Mn) in protein bands were measured using the synchrotron radiation X-ray fluorescence (SRXRF) analysis. At least 7 Mn-containing bands

8 Fe-containing bands

6 Cu-containing bands

and 8 Zn-containing bands in microsome were observed in tumor tissues and their surrounding nontumor tissues for the 5 individuals with HCC. The metal contents in protein bands of tumor tissues were generally similar to those of nontumor tissues

except for bands with pIs of 5.9 and 9.3. The Fe content in the band of 5.9 of tumor microsome was only 40% of that in nontumor

but the Cu and Zn contents are 2- and 3.5-fold higher

respectively

in the band of 9.3 compared to that of nontumor tissues. The results suggest that the metal distribution patterns of various metal-containing bands are distinguishable between the tumor and nontumor tissues. The difference of the metal distribution patterns may be related to the carcinogenesis of the liver tissues.