ABSTRACT
The effects of a number of cytotoxic drugs are influenced by cellular reduction/oxidation (redox) state. In the present study, we attempt to explore if dicoumarol, an inhibitor of NADPH: quinone oxidoreductase (NQO1), alters the cellular redox state and how this alteration affects the redox-related apoptosis. Flow cytometry was used to assess the reactive oxygen species (ROS) level and apoptotic rates of HeLa cells treated with arsenic trioxide (As2O3) alone or in combination with natural anthraquinone emodin and dicoumarol or plus N-acetyl-cysteine. Western blot, immunofluorescence, electrophoretic mobility shift assay and luciferase assay were used to detect Nuclear Factor kappa B (NF-kappaB) activation. The results showed that dicoumarol synergized with emodin to sensitize HeLa cells to As2O3-induced apoptosis through raising the ROS level. More notably, this enhanced susceptibility was associated with a ROS-mediated inhibition of NF-kappaB activation in which the combinative treatment with dicoumarol prevented NF-kappaB from binding to target DNA. It was suggested that dicoumarol in combination with anthraquinones might be a novel strategy to expand the chemotherapeutic spectrum of As2O3 by means of interfering the cellular redox state.
Subject(s)
Apoptosis/drug effects , Arsenicals/pharmacology , Dicumarol/pharmacology , Emodin/pharmacology , NF-kappa B/metabolism , Oxides/pharmacology , Reactive Oxygen Species/metabolism , Arsenic Trioxide , Dose-Response Relationship, Drug , Drug Combinations , Drug Synergism , Enzyme Inhibitors/pharmacology , HeLa Cells , Humans , Oxidation-Reduction/drug effectsABSTRACT
Preclinical studies demonstrate that intratumoral delivery of adenovirus expressing IL-2 eradicates pre-established tumors in mice and confers immune protection from rechallenge. To explore the activity of AdCAIL-2 in prostate cancer, a Phase I clinical trial was conducted in patients with localized disease and Gleason score >7 or prostate-specific antigen (PSA) >10 plus Gleason score 7. A total of 12 patients were injected 4 weeks prior to prostatectomy in a dose-escalation study at doses of 10(9), 5 x 10(9) and 10(10) PFU of virus. No dose-limiting toxicity was observed. Side effects included perineal discomfort, hematuria, flu-like symptoms in two patients and urinary hesitancy in one patient. Pathology demonstrated an inflammatory response consisting predominantly of CD3+CD8+ T lymphocytes with areas of tumor necrosis. Intracellular cytokine staining of tumor-infiltrating lymphocytes demonstrated increases in both gamma-interferon and IL-4 secreting T cells after vaccination. PSA levels fell in five of five evaluable patients treated at the lowest dose (mean decline of 33.3%, range 17-69%). At higher doses, PSA values initially increased after injection, then fell to baseline prior to surgery. This trial demonstrates the feasibility and safety of intraprostatic adenovector-mediated IL-2 gene delivery.
