Lack of oxidative phosphorylation and low mitochondrial membrane potential decrease susceptibility to apoptosis and do not modulate the protective effect of Bcl-xL in osteosarcoma cells

Department of Neurology, University of Miami, School of Medicine, Miami, Florida 33136, USA.
Journal of Biological Chemistry (Impact Factor: 4.57). 04/2000; 275(10):7087-94.
Source: PubMed


We explored the role of low mitochondrial membrane potential (DeltaPsim) and the lack of oxidative phosphorylation in apoptosis by assessing the susceptibility of osteosarcoma cell lines with and without mitochondrial DNA to staurosporine-induced death. Our cells without mitochondrial DNA had low DeltaPsim and no functional oxidative phosphorylation. Contrary to our expectation, these cells were more resistant to staurosporine-induced death than were the parental cells. This reduced susceptibility was associated with decreased activation of caspase 3 but not with the mitochondrial permeability transition pore or cytochrome c release from the mitochondria. Apoptosis in both cell lines was associated with an increase in DeltaPsim. Bcl-x(L) could protect both cell types against caspase 3 activation and apoptosis by a mechanism that does not appear to be mediated by mitochondrial function or modulation of DeltaPsim. Nevertheless, we found that Bcl-x(L) expression can stimulate cell respiration in cells with mitochondrial DNA. Our results showed that the lack of functional oxidative phosphorylation and/or low mitochondrial membrane potential are associated with an antiapoptotic effect, possibly contributing to the development of some types of cancer. It also reinforces a model in which Bcl-x(L) can exert an antiapoptotic effect by stimulating oxidative phosphorylation and/or inhibiting caspase activation.

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    • "The Leishmania promastigotes were subjected to treatment with CopNEC-AmB, AmB, CopNEC and Cop for different time points (0, 6, 24 and 48 h), incubated for 7 min with 10 mM JC-1 (Sigma-Aldrich) at 37°C, washed and resuspended in medium. The relative mitochondrion potential (Δψm) value was calculated from the ratio of fluorescence at 590 to 530 nm (Dey and Moraes, 2000). "
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    ABSTRACT: To improve oral delivery of AmB by achieving increased oral bioavailability and synergistically enhanced antileishmanial activity using copaiba oil (Cop) through nano-emulsified carrier system (CopNEC). The AmB encapsulated nano-emulsified carrier (CopNEC-AmB) comprised of Cop, d-alpha Tocopheryl Polyethylene Glycol 1000 Succinate and phosphatidylcholine was prepared by high pressure homogenization method. Stability study of CopNEC-AmB was carried out in simulated gastric fluid and simulated intestinal fluid. The CopNEC-AmB and plain AmB were compared for in vitro antileishmanial activity, their pharmacokinetics, organ distribution and toxicity profiling. The optimized CopNEC-AmB has globule size of 127±21 nm, PDI 0.11±0.02, and zeta potential (-)38.5±2.7 with encapsulation efficiency 91.9±1.4 %w/w. The high resolution transmission electron microscopy illustrates spherical particle geometry with homogeny in their sizes. The optimized CopNEC-AmB was found to be stable in gastro-intestinal fluids showing insignificant changes in globule size and encapsulation efficiency. The AUC0-48 value of CopNEC-AmB in rats was significantly improved showing 7.2 folds higher oral bioavailability than free drug. The in vitro antileishmanial activity of CopNEC-AmB was significantly higher (p<0.05) than the free drug because copaiba oil synergistically enhanced chemotherapy of leishmaniasis by causing drastic changes in morphology of Leishmania parasite and rupture of the plasma membrane with loss of their contents. The CopNEC-AmB showed significantly lesser hemolytic toxicity and cell cytotoxicity, and absence of any changes in histopathology of kidney tissues as compared to free drug. This prototype CopNEC formulation showed improved bioavailability and nontoxic synergistic antileishmanial chemotherapy of AmB due to copaiba oil against leishmaniasis. This article is protected by copyright. All rights reserved.
    British Journal of Pharmacology 03/2015; 172(14). DOI:10.1111/bph.13149 · 4.84 Impact Factor
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    • "Mitochondrial membrane potential determination. The mitochondrial membrane potential (DYm) was monitored by using JC-1 dye as a probe (Dey & Moraes, 2000). JC-1 is a cationic mitochondrial vital dye that is lipophilic and becomes concentrated in the mitochondria in proportion to DYm: more dye accumulates in mitochondria with a greater DYm and ATP-generating capacity (Sudhandiran & Shaha, 2003). "
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    • "We reported earlier that partial mtDNA depletion in C2C12 skeletal myoblasts and A549 lung carcinoma cells results in highly invasive phenotypes that are resistant to chemically induced apoptosis (Amuthan et al., 2002; Biswas et al., 2005a). Induced proliferation and tumor growth promotion by mitochondrial stress signaling in immortalized C2C12 myoblasts is of special significance for cancer promotion (Amuthan et al., 2001; Biswas et al., 2005a; Guha et al., 2007) Others have shown that mtDNA depletion induces resistance to apoptosis in 143B osteosarcoma (Dey and Moraes, 2000), T47D breast carcinoma (Yu et al., 2009), SK-Hep1 (Kim et al., 2002), and prostate cancer cells (Moro et al., 2009). Depletion of mtDNA in LNCaP androgen-dependent prostate carcinoma cells induces progression to androgen independence , with increased cell migration and resistance to common chemotherapeutic agents (Higuchi et al., 2006; Moro et al., 2008). "
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