Tetraarsenic Hexoxide Induces Beclin-1-Induced Autophagic Cell Death as well as Caspase-Dependent Apoptosis in U937 Human Leukemic Cells
ABSTRACT Tetraarsenic hexaoxide (As(4)O(6)) has been used in Korean folk remedy for the treatment of cancer since the late 1980s, and arsenic trioxide (As(2)O(3)) is currently used as a chemotherapeutic agent. However, evidence suggests that As(4)O(6)-induced cell death pathway was different from that of As(2)O(3). Besides, the anticancer effects and mechanisms of As(4)O(6) are not fully understood. Therefore, we investigated the anticancer activities of As(4)O(6) on apoptosis and autophagy in U937 human leukemic cells. The growth of U937 cells was inhibited by As(4)O(6) treatment in a dose- and a time-dependent manner, and IC(50) for As(4)O(6) was less than 2 μM. As(4)O(6) induced caspase-dependent apoptosis and Beclin-1-induced autophagy, both of which were significantly attenuated by Bcl-2 augmentation and N-acetylcysteine (NAC) treatment. This study suggests that As(4)O(6) should induce Beclin-1-induced autophagic cell death as well as caspase-dependent apoptosis and that it might be a promising agent for the treatment of leukemia.
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ABSTRACT: In recent years, research on the autophagic process has greatly increased, invading the fields of biology and medicine. Several markers of the autophagic process have been discovered and various strategies have been reported studying this molecular process in different biological systems in both physiological and stress conditions. Furthermore, mechanisms of metalloid- or heavy metal-induced toxicity continue to be of interest given the ubiquitous nature and distribution of these contaminants in the environment where they often play the role of pollutants of numerous organisms. The aim of this review is a critical analysis and correlation of knowledge of autophagic mechanisms studied under stress for the most common arsenic (As) and cadmium (Cd) compounds. In this review we report data obtained in different experimental models for each compound, highlighting similarities and/or differences in the activation of autophagic processes. A more detailed discussion will concern the activation of autophagy in Cd-exposed sea urchin embryo since it is a suitable model system that is very sensitive to environmental stress, and Cd is one of the most studied heavy metal inductors of stress and modulator of different factors such as: protein kinase and phosphatase, caspases, mitochondria, heat shock proteins, metallothioneins, transcription factors, reactive oxygen species, apoptosis and autophagy.12/2012; 1(3):597-616. DOI:10.3390/cells1030597
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ABSTRACT: Arsenic hexoxide (As4O6) has been used in Korean folk remedy for the treatment of cancer since the late 1980s. Evidence suggests that the anticancer effects of As4O6 are different from those of As2O3. Tumor necrosis factor-α (TNF-α) is generally increased in advanced cancer and is closely related to cancer progression, although it has cancer-killing effects. The reason is that TNF-α activates nuclear factor-κB (NF-κB) that is involved in cell proliferation, invasion, drug resistance and metastasis. In the present study, we investigated the effects of As4O6 on NF-κB activity, NF-κB-mediated cellular responses, and NF-κB-regulated gene expressions involved in metastasis at the concentrations of As4O6 where no cytotoxicity was observed. As4O6 suppressed NF-κB activation in both TNF-α-treated and control cells, and also suppressed IκB phosphorylation in a time-dependent manner, suggesting the suppression of NF-κB results, in part, from the inhibition of IκB degradation. We also confirmed the anti-NF-κB activity of As4O6 with synergism with TNF-α by augmenting caspase-8 activation. As4O6 also suppressed NF-κB activation induced by TNF-α, and some of the downstream NF-κB-regulated proteins involved in cancer proliferation, anti-apoptosis and metastasis. In conclusion, the present study demonstrated that As4O6 has anticancer properties by inhibiting NF-κB activation and NF-κB-regulated proteins at least in part through the inhibition of IκB phosphorylation, especially in the conditions of advanced cancer where TNF-α is highly secreted.Oncology Reports 03/2014; 31(5). DOI:10.3892/or.2014.3085 · 2.19 Impact Factor
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ABSTRACT: Oyaksungisan (OY) is a traditional herbal formula broadly used to treat beriberi, vomiting, diarrhea, and circulatory disturbance in Asian countries from ancient times. The effect of OY on cancer, however, was not reported until now. In this study, we have demonstrated that OY inhibits cell proliferation and induces cell death via modulating the autophagy on human colon cancer cells. In HCT116 cells, OY increased the ratio of LC3-II/LC3-I, a marker of autophagy, and treatment with 3-MA, an inhibitor of autophagy, and considerably reduced the formation of autophagosomes. In addition, OY regulated mitogen-activated protein kinase (MAPK) cascades; especially, JNK activation was closely related with autophagy effect by OY in HCT116 cells. Our results indicate that autophagy induction is responsible for the antiproliferative effect by OY, despite the weak apoptosis induction in HCT116 cells. In conclusion, OY might have a potential to be developed as an herbal anticancer remedy.Evidence-based Complementary and Alternative Medicine 03/2013; 2013:231874. DOI:10.1155/2013/231874 · 2.18 Impact Factor