cytochrome-c-t and Fanconi-Anemia

In the present study, we downregulated FANCF expression by small interfering RNA (siRNA) in OVCAR ovarian cancer cells to address the effects of decreased FANCF expression on the function of the Fanconi anemia (FA)/breast cancer susceptibility gene (BRCA) pathway. Furthermore, we investigated whether this method increases the sensitivity of OVCAR3 cells to adriamycin (ADM) and the possible mechanism(s). We found that silencing of FANCF inactivated the FA/BRCA pathway by decreasing the monoubiquitination and focus formation of FANCD2 and reduced the function of the FA/BRCA pathway, resulting in the inhibition of cell proliferation, increased cell apoptosis and DNA damage in OVCAR3 cells. Moreover, we observed that silencing of FANCF enhanced the antiproliferative effect of ADM in OVCAR3 cells and increased ADM intracellular accumulation consequently sensitizing OVCAR3 cells to ADM. Furthermore, silencing of FANCF increased cell apoptosis of OVCAR3 cells which was caused by decreased mitochondrial membrane potential (MMP)-induced DNA damage, activated Jun N-terminal kinase (JNK), increased release of cytochrome c, increased expression of cleaved caspase-3 and poly(ADP-ribose) polymerase (PARP) dependent on JNK activation following treatment of ADM. Collectively, we confirm that silencing of FANCF sensitizes OVCAR3 ovarian cancer cells to ADM, suggesting that FANCF may serve as a potential target for therapeutic strategies in the treatment of ovarian cancer.

Topics: Apoptosis; BRCA1 Protein; Caspase 3; Cell Line, Tumor; Cell Proliferation; Combined Modality Therapy; Cytochromes c; DNA Damage; Down-Regulation; Doxorubicin; Fanconi Anemia; Fanconi Anemia Complementation Group F Protein; Female; Humans; JNK Mitogen-Activated Protein Kinases; Membrane Potential, Mitochondrial; Ovarian Neoplasms; Poly(ADP-ribose) Polymerases; RNA Interference; RNA, Small Interfering; Signal Transduction

Thalassemia (thal) and Fanconi's Anemia (FA) are genetic disorders associated with iron-catalyzed free radical damage. Therefore, the contemporary and most successful treatment of thalassemic patients depends on the application of iron (Fe) chelators. However, there is another pathway of free radical-mediated damaging processes in these pathologies, depending on the interplay between physiological free radicals superoxide and nitric oxide (NO). In the present study, we have considered the major routes of superoxide damaging effects in mitochondria: the initiation of apoptosis through the reduction of cytochrome c, the activation of uncoupled proteins by superoxide, and the mitochondrial damage due to the competition between superoxide and nitric oxide at the Complex IV site (cytochrome oxidase). The application of the effective scavengers superoxide dismutases and flavonoids for the treatment of thalassemic and FA patients, is discussed.

Topics: Apoptosis; Catalysis; Cytochromes c; Fanconi Anemia; Flavonoids; Free Radical Scavengers; Free Radicals; Humans; Iron; Iron Chelating Agents; Mitochondria; Nitric Oxide; Superoxide Dismutase; Superoxides; Thalassemia