Carboplatin induces apoptotic cell death through downregulation of constitutively active nuclear factor-kappaB in human HPV-18 E6-positive HEp-2 cells.
ABSTRACT Because the role of nuclear factor kappaB (NF-kappaB) is in cellular growth control and neoplasia, we explored the status of NF-kappaB and investigated its role in survival of human HPV-18 E6-positive HEp-2 cells. We observed accumulation of p65 in the nucleus. Moreover, without any external stimulus constitutive NF-kappaB DNA binding and transactivation activity were detected in HEp-2 cells. Treatment with NF-kappaB inhibitor curcumin (diferuloylmethane) and transient transfection of the mutant form of IkappaBalpha, IkappaBalpha super repressor (IkappaBalpha-SR), suppressed constitutive NF-kappaB activity as well as proliferation, suggesting that constitutive NF-kappaB activity is required for the survival of HEp-2 cells. Carboplatin treatment downregulated constitutive NF-kappaB activity and prevented nuclear retention of p65. Further, carboplatin also suppressed the constitutive IkappaBalpha phosphorylation leading to stabilization of IkappaBalpha protein in the cells. Carboplatin inhibited NF-kappaB binding to its response element present in Bcl-2 promoter resulting in downregulation of antiapoptotic Bcl-2 protein. Thus, our results for the first time indicate that constitutive NF-kappaB has a significant role in the survival of HPV-18 E6-positive HEp-2 cells. Moreover, inactivation of NF-kappaB is one of the mechanisms underlying the induction of carboplatin-mediated apoptosis in HPV-18 E6-positive cancer cells.
- SourceAvailable from: ncbi.nlm.nih.govMayo Clinic Proceedings 03/2011; 86(3):260-1. · 5.79 Impact Factor
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ABSTRACT: There is constant increase in number of diabetic cases thereby giving it status of a serious epidemic. Diabetes increases the risk of occurrence of several cancers including breast cancer and may also have a serious impact on the outcome of cancer treatment. In the present study we investigated effect of hyperglycemia on cytotoxic efficacy of carboplatin and 5-fluorouracil in MCF-7 cells. MCF-7 cells were grown in 5.5 or 25 mM glucose chronically. We show that hyperglycemia favors proliferation of MCF-7 cells and increases expression of cell cycle regulatory proteins cyclin E and cdk-2. Hyperglycemia enhances cytotoxicity of carboplatin and 5-fluorouracil in MCF-7 cells by approximately 30% and decreases their IC50 by 1.5- and 1.3-folds, respectively. Hyperglycemia reduces expression of P-glycoprotein and promotes cell killing by increasing drug accumulation. Treatment with 40 µM verapamil, an inhibitor of P-gp activity specifically increases killing of MCF-7 cells cultured in 5.5 mM glucose. Further, this effect is synergized by elevated reactive oxygen species and treatment with N-Acetylcysteine, an inhibitor of ROS, increases survival by 30 and 18% in carboplatin- and 5-fluorouracil-treated cells cultured in high glucose, respectively. Cytotoxicity of these drugs is associated with reduced activation of Akt and decreased transcriptional activation of NF-κB. In conclusion, hyperglycemia potentiates cytotoxicity of drugs by reducing P-gp expression and, increased ROS levels may partially or completely contribute to enhanced toxicity.Journal of Cellular Biochemistry 05/2011; 112(10):2942-52. · 3.06 Impact Factor
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ABSTRACT: The use of an "over 1000-nm near-infrared (NIR) in vivo fluorescence bioimaging" system based on lanthanide containing inorganic nanostructures emitting in the visible and NIR range under 980-nm excitation is proposed. It may overcome problems of currently used biomarkers including color fading, phototoxicity and scattering. Gd(2)O(3):Er(3+),Yb(3+) nanoparticles and nanorods showing upconversion and NIR emission are synthesized and their cytotoxic behavior is investigated by incubation with B-cell hybridomas and macrophages. Surface modification with PEG-b-PAAc provides the necessary chemical durability reducing the release of toxic Gd(3+) ions. NIR fluorescence microscopy is used to investigate the suitability of the nanostructures as NIR-NIR biomarkers. The in vitro uptake of bare and modified nanostructures by macrophages is investigated by confocal laser scanning microscopy. In vivo investigations revealed nanostructures in liver, lung, kidneys and spleen a few hours after injection into mice, while most of the nanostructures have been removed from the body after 24 h.Journal of Materials Science Materials in Medicine 05/2012; 23(10):2399-412. · 2.14 Impact Factor