Study of the effects of a new pyrazolecarboxamide: changes in mitochondria and induction of apoptosis.

Drug resistance of cancer cells is often correlated with the evasion of apoptosis, thus a major goal in cancer research is to search for compounds able to counteract cancer by promoting apoptosis. A variety of compounds with anticancer activity are characterised by the presence of the pyrazole as core nucleus. We synthesised a panel of pyrrolyl-pyrazole-carboxamides and we focused on the new compound RS 2780 (N-2-phenylethyl 1-(4-chlorophenyl)-3-methyl-5-pyrrolylpyrazole-4-carboxamide). The biological effects of RS 2780 on cell proliferation and viability were first evaluated on human HeLa cancer cells. As revealed by cell growth and viability experiments, a 24-h treatment of HeLa cells with increasing concentrations of RS 2780 (ranging from 0.1 to 100 microM) proved to inhibit cell proliferation and to affect cell viability. Notably, the new compound was effective also on colon carcinoma SW613-B3 cells, which are extremely resistant to most drugs, while it does not alter the proliferation of normal fibroblasts. We observed that RS 2780 interferes with the structural and functional properties of mitochondria, leading to the activation of the mitochondria-dependent apoptotic pathway. Apoptosis occurrence was supported by a number of morphological and biochemical hallmarks, including chromatin condensation, internucleosomal DNA fragmentation, PARP-1 cleavage and caspase activation. In conclusion, our results demonstrate for the first time the antiproliferative properties of the new compound RS 2780 on HeLa and SW613-B3 cancer cells and show that its effects on mitochondria lead to apoptosis.

Lack of molecular relationships between lipid peroxidation and mitochondrial DNA single strand breaks in isolated rat hepatocytes and mitochondria.

We investigated the molecular relationships between lipid peroxidation and mitochondrial DNA (mtDNA) single strand breaks (ssb) in isolated rat hepatocytes and mitochondria exposed to tert-butylhydroperoxide (TBH). Our results show that mtDNA ssb induced by TBH are independent of lipid peroxidation and dependent on the presence of iron and of hydroxyl free radicals. These data contribute to the definition of the mechanisms whereby mtDNA ssb are induced and provide possible molecular targets for the prevention of this kind of damage in vivo.