Heme biosynthesis pathway regulation in a model of hepatocarcinogenesis pre-initiation
1. 1. Heme regulation before the appearance of hyperplastic nodules was investigated in mice models of hepatocarcinogenesis. 2. 2. With this aim 5-aminolaevulinate synthetase (ALA-S), microsomal heme-oxygenase (MHO), mitochondrial and cytoplasmic rhodanese activities were examined throughout a perio...
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| Autores principales: | , , , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_03050491_v103_n1_p251_Polo |
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| Sumario: | 1. 1. Heme regulation before the appearance of hyperplastic nodules was investigated in mice models of hepatocarcinogenesis. 2. 2. With this aim 5-aminolaevulinate synthetase (ALA-S), microsomal heme-oxygenase (MHO), mitochondrial and cytoplasmic rhodanese activities were examined throughout a period of 35 days in animals exposed to dietary p-dimethylaminoazobenzene (DAB). 3. 3. ALA-S activity was significantly diminished (50%) on day 14, then showing a sharply rising profile from day 28 onwards, and reaching 350% on day 35. 4. 4. A similar profile was observed for mitochondrial rhodanese activity. 5. 5. Changes in MHO and cytoplasmic rhodanese activities were almost the opposite to those observed for ALA-S. 6. 6. The distinctive alteration in mitochondrial and cytoplasmic rhodanese would suggest that it plays a subtle role in ALA-S regulation during carcinogenesis initiation through a mechanism that appears to involved subcellular localization controls perhaps by means of the breakage of cystine trisulphide postulated to act as an ALA-S activator. 7. 7. Taking into account the present results, we suggest a probable mechanism for the onset of hepatocarcinogenesis that includes a primary activating liver status, provoking biochemical aberration leading to the stage of initiation of hepatocarcinogenesis involving the whole organ. © 1992. |
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