d-609 and Necrosis

The growth-stimulatory actions of tumor necrosis factor alpha (TNF-alpha) after partial hepatectomy (PH) are difficult to reconcile with its well-established role in the genesis of liver injury. The lethal actions of TNF are thought to involve the induction of oxidant production by mitochondria. It is not known if TNF initiates mitochondrial oxidant production after PH. Furthermore, if this potentially toxic response follows PH, it is not clear how hepatocytes defend themselves sufficiently so that replication, rather than death, occurs. These studies test the hypothesis that TNF does increase mitochondrial oxidant production after PH but that these oxidants primarily promote the induction of antioxidant defenses in regenerating hepatocytes. Consistent with this concept, H2O2 production by liver mitochondria increases from 5 minutes to 3 hours after PH, beginning before the transient inductions of hepatic NF kB activity (which peaks at 30 minutes post-PH) and uncoupling protein-2 (UCP-2) (which begins around 30 minutes and peaks from 6-24 hours post-PH). Pretreatment with neutralizing anti-TNF antibodies, which inhibits hepatocyte DNA synthesis after PH, also reduces post-PH hepatic mitochondrial oxidant production by 80% and inhibits NF kappaB activation and UCP-2 induction by 50% and 80%, respectively. In contrast, pretreatment with D609, an agent that inhibits phosphatidylcholine-specific phospholipase C, neither inhibits regenerative induction of mitochondrial oxidant production, UCP-2 expression, nor hepatocyte DNA synthesis, although it inhibits NF kappaB activation by 50%. Given published evidence that NF kappaB is antiapoptotic and that UCP-2 may decrease mitochondrial oxidant production in some cells, these results suggest that TNF-dependent increases in oxidant production by liver mitochondria promote the induction of antioxidant defenses in the regenerating liver.

Topics: Animals; Antibodies; Bridged-Ring Compounds; DNA; Glycogen; Hydrogen Peroxide; Ion Channels; Liver; Liver Regeneration; Male; Membrane Transport Proteins; Mice; Mice, Inbred C57BL; Mitochondria, Liver; Mitochondrial Proteins; Necrosis; Norbornanes; Oxidants; Phosphodiesterase Inhibitors; Proteins; Thiocarbamates; Thiones; Tumor Necrosis Factor-alpha; Uncoupling Protein 2

Recombinant human tumor necrosis factor (rh TNF) when administered intravenously together with the phospholipase C inhibitor tricyclodecan-9-yl-xanthogenate (D609) and lauric acid (C12), leads to the partial regression of various human tumor transplants in athymic mice. Extensive necrosis occurred after a single intravenous infusion, with no detectable side effects. TNF-mediated cytotoxicity was found to be correlated with the depletion of energy in HeLa cells. The activity of rh TNF was enhanced by the absence of glucose, while it was reduced by addition of extraneous ATP. In the presence of rh TNF, D609, and C12, cellular energy metabolism was almost completely switched to glycolysis. Under these conditions the cytocidal activity of rh TNF on HeLa cells was amplified at least 60-fold.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Bridged-Ring Compounds; Carcinoma; Cell Line; Drug Screening Assays, Antitumor; Female; Humans; Lauric Acids; Mice; Mice, Nude; Necrosis; Neoplasm Transplantation; Norbornanes; Recombinant Proteins; Specific Pathogen-Free Organisms; Thiocarbamates; Thiones; Transplantation, Heterologous; Tumor Necrosis Factor-alpha

Therapeutic effects were obtained after systemic treatment of athymic mice bearing an epidermoid non-small cell human lung carcinoma (NSCLC) xenograft with tricyclodecan-9-yl xanthogenate (D609) and the potassium salt of a fatty (dodecanoic) acid. Extensive intratumoral necrosis was observed 3 days after the treatment.

Topics: Animals; Antineoplastic Agents; Bridged-Ring Compounds; Carcinoma, Non-Small-Cell Lung; Drug Combinations; Humans; Lauric Acids; Lung Neoplasms; Mice; Mice, Nude; Necrosis; Neoplasm Transplantation; Norbornanes; Thiocarbamates; Thiones