Copper and zinc metabolism with solid tumor growth

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Abstract
The variation in copper and zinc metabolism with tumor growth appears to relate directly to progression or regression of the disease. Historically, elevations in serum copper have been used as clinical indicators in hematological neoplasms since the early 1960s. More recently, we have monitored breast, colo-rectal, and lung cancer patients for a six-month period through courses of cytotoxic chemotherapy to determine copper and zinc changes with tumor growth. Groups were divided into responders and nonresponders blind to their serum copper and zinc levels. Trends in elevated serum copper with active disease have shown similar trends in decreasing values with effective therapy, but normalization was at a slower rate. Serum zinc levels in the same patients were markedly below normal and did not increase in the study period. The clinical significance or elevated serum copper and depressed serum zinc is discussed and the potential relationship between the two elements is explored. A solid tumor-bearing rat model, mammary adenocarcinoma R 3230 AC, has detailed more of the changes in copper and zinc metabolism with solid tumor growth. Serum copper and zinc varied with tumor mass, as in clinical studies. Liver values of the two essential metals did not change significantly, but liver-related copper-containing enzymes showed marked variations. Ceruloplasmin in serum increased with increasing tumor mass, as would be expected with the increased serum copper levels. Cytochrome c oxidase activity in liver homogenates from tumor-bearing animals was significantly depressed.