title: Increased sensitivity of African American triple negative breast cancer cells to nitric oxide-induced mitochondria-mediated apoptosis.
abstract: Breast cancer is a complex heterogeneous disease where many distinct subtypes are found. Younger African American (AA) women often present themselves with aggressive form of breast cancer with unique biology which is very difficult to treat. Better understanding the biology of AA breast tumors could lead to development of effective treatment strategies. Our previous studies indicate that AA but not Caucasian (CA) triple negative (TN) breast cancer cells were sensitive to nitrosative stress-induced cell death. In this study, we elucidate possible mechanisms that contribute to nitric oxide (NO)-induced apoptosis in AA TN breast cancer cells.
  
  
  
  Breast cancer cells were treated with various concentrations of long-acting NO donor, DETA-NONOate and cell viability was determined by trypan blue exclusion assay. Apoptosis was determined by TUNEL and caspase 3 activity as well as changes in mitochondrial membrane potential. Caspase 3 and Bax cleavage, levels of Cu/Zn superoxide dismutase (SOD) and Mn SOD was assessed by immunoblot analysis. Inhibition of Bax cleavage by Calpain inhibitor, and levels of reactive oxygen species (ROS) as well as SOD activity was measured in NO-induced apoptosis. In vitro and in vivo effect of NO treatment on mammary cancer stem cells (MCSCs) was assessed.
  
  
  
  NO induced mitocondria-mediated apoptosis in all AA but not in CA TN breast cancer cells. We found significant TUNEL-positive cells, cleavage of Bax and caspase-3 activation as well as depolarization mitochondrial membrane potential only in AA TN breast cancer cells exposed to NO. Inhibition of Bax cleavage and quenching of ROS partially inhibited NO-induced apoptosis in AA TN cells. Increase in ROS coincided with reduction in SOD activity in AA TN breast cancer cells. Furthermore, NO treatment of AA TN breast cancer cells dramatically reduced aldehyde dehydrogenase1 (ALDH1) expressing MCSCs and xenograft formation but not in breast cancer cells from CA origin.
  
  
  
  Ethnic differences in breast tumors dictate a need for tailoring treatment options more suited to the unique biology of the disease.
authors.affiliation: California State University, Dominguez Hills, Los Angeles, CA, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Martinez
authors.affiliation: Columbia University New York, New York, NY, 10027, USA.
authors.forename: Easter
authors.initials: E
authors.lastname: Thames
authors.affiliation: Charles R. Drew University of Medicine and Science, Los Angeles, CA, 90059, USA.
authors.forename: Jinna
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA.|Jonsson Comprehensive Cancer Center at UCLA, Los Angeles, CA, 90095, USA.
authors.forename: Gautam
authors.initials: G
authors.lastname: Chaudhuri
authors.affiliation: Charles R. Drew University of Medicine and Science, Los Angeles, CA, 90059, USA.|Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA.|Jonsson Comprehensive Cancer Center at UCLA, Los Angeles, CA, 90095, USA.
authors.forename: Rajan
authors.initials: R
authors.lastname: Singh
authors.affiliation: Charles R. Drew University of Medicine and Science, Los Angeles, CA, 90059, USA. shehlapervin@cdrewu.edu.|Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA. shehlapervin@cdrewu.edu.|Jonsson Comprehensive Cancer Center at UCLA, Los Angeles, CA, 90095, USA. shehlapervin@cdrewu.edu.|Division of Endocrinology and Metabolism, Charles R. Drew University of Medicine and Science, 1731 East 120th Street, Los Angeles, CA, 90059, USA. shehlapervin@cdrewu.edu.
authors.forename: Shehla
authors.initials: S
authors.lastname: Pervin
mesh_terms: D001741:Black or African American; D000080924:Aldehyde Dehydrogenase 1 Family; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008819:Mice, Nude; D008928:Mitochondria / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000378:metabolism / Q000494:pharmacology; D009603:Nitroso Compounds / Q000378:metabolism / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D050697:Retinal Dehydrogenase / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy* / Q000208:ethnology / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D009569:Nitric Oxide; D013482:Superoxide Dismutase; D000080924:Aldehyde Dehydrogenase 1 Family; C510223:ALDH1A1 protein, human; C515028:ALDH1A1 protein, mouse; D050697:Retinal Dehydrogenase; D053148:Caspase 3
keywords: African American; Breast cancer; Health disparity; Unique biology