Tin-protoporphyrin inhibits heme oxygenase and prevents the decline in hepatic heme and cytochrome P-450 contents produced in nude mice by tumor transplantation |
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Authors: | P S Wissel R A Galbraith S Sassa A Kappas |
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Institution: | Rockefeller University, New York, NY 10021. |
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Abstract: | Heme and hemeprotein perturbations are present in nude mice bearing transplanted tumors. Hepatic microsomal heme oxygenase activity is increased 50-100% in tumor bearing nu/nu mice when compared with normal controls. This elevation in activity of the rate-limiting enzyme of heme degradation is associated with a 50% depletion of microsomal heme and cytochrome P-45 concentrations in liver. The synthetic heme analogue, Sn-protoporphyrin, a potent inhibitor of heme oxygenase, lowers the activity of heme oxygenase in tumor bearing animals to below control levels. This effect is associated with a normalization of hepatic heme and cytochrome P-450 contents. These findings might have implications for protecting normal cells during tumor growth and chemotherapy. |
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