title: Interplay between autophagy and apoptosis mediated by copper oxide nanoparticles in human breast cancer cells MCF7.
abstract: BACKGROUND
  Metal oxide nanoparticles are well known to generate oxidative stress and deregulate normal cellular activities. Among these, transition metals copper oxide nanoparticles (CuO NPs) are more compelling than others and able to modulate different cellular responses.
  
  
  METHODS
  In this work, we have synthesized and characterized CuO NPs by various biophysical methods. These CuO NPs (~30nm) induce autophagy in human breast cancer cell line, MCF7 in a time- and dose-dependent manner. Cellular autophagy was tested by MDC staining, induction of green fluorescent protein-light chain 3 (GFP-LC3B) foci by confocal microscopy, transfection of pBABE-puro mCherry-EGFP-LC3B plasmid and Western blotting of autophagy marker proteins LC3B, beclin1 and ATG5. Further, inhibition of autophagy by 3-MA decreased LD50 doses of CuO NPs. Such cell death was associated with the induction of apoptosis as revealed by FACS analysis, cleavage of PARP, de-phosphorylation of Bad and increased cleavage product of caspase 3. siRNA mediated inhibition of autophagy related gene beclin1 also demonstrated similar results. Finally induction of apoptosis by 3-MA in CuO NP treated cells was observed by TEM.
  
  
  RESULTS
  This study indicates that CuO NPs are a potent inducer of autophagy which may be a cellular defense against the CuO NP mediated toxicity and inhibition of autophagy switches the cellular response into apoptosis.
  
  
  CONCLUSIONS
  A combination of CuO NPs with the autophagy inhibitor is essential to induce apoptosis in breast cancer cells.
  
  
  CONCLUSIONS
  CuO NP induced autophagy is a survival strategy of MCF7 cells and inhibition of autophagy renders cellular fate to apoptosis.
authors: Department of Life Science and Biotechnology, Jadavpur University, Kolkata, 700 032, India.
authors: Dipranjan
authors: D
authors: Laha
authors: Arindam
authors: A
authors: Pramanik
authors: Jyotirindra
authors: J
authors: Maity
authors: Ananda
authors: A
authors: Mukherjee
authors: Panchanan
authors: P
authors: Pramanik
authors: Aparna
authors: A
authors: Laskar
authors: Parimal
authors: P
authors: Karmakar
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D001343:Autophagy; D000071186:Beclin-1; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D002103:Cadaverine / Q000031:analogs & derivatives / Q000378:metabolism; D002453:Cell Cycle; D049109:Cell Proliferation; D003300:Copper / Q000008:administration & dosage*; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D061986:MCF-7 Cells; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D053768:Metal Nanoparticles / Q000008:administration & dosage*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; C477012:MAP1LC3A protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins; D003300:Copper; C008542:monodansylcadaverine; D002103:Cadaverine; C000520:cuprous oxide
keywords: 3-MA; 3-methyladenine; Apoptosis; Autophagy; Copper oxide nanoparticle; MDC; N-acetyl cysteine; NAC; Small interfering RNA; mM; milli molar; monodansylcadaverine