title: Pretreatment with AT-101 enhances tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis of breast cancer cells by inducing death receptors 4 and 5 protein levels.
abstract: OBJECTIVE
  Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily and has been shown to induce extrinsic pathway of apoptosis in many types of cancer cells. AT-101, an (-)-enantiomer of gossypol, is a potent anticancer agent that is shown to be an inhibitor of Bcl-2/Bcl-XL. In this study, we searched whether pretreatment with either of these drugs would result in the enhancement of apoptosis through induction of death receptors and activation of mitochondrial pathways within breast cancer cells.
  
  
  METHODS
  Human breast cancer (MCF-7 and MDA-MB-231) and normal breast cells (MCF-10A) were treated with drugs alone/in combination/sequentially. XTT cell viability assay was used to evaluate cytotoxicity. For showing apoptosis, both DNA Fragmentation and caspase 3/7 activity measurements were done. ELISA and Western blot analysis were done to assess DR4 and DR5 protein levels. The expression levels of apoptotic proteins were assessed by human apoptosis antibody array.
  
  
  RESULTS
  The sequential treatment of AT-101 followed by TRAIL resulted in significant synergistic cytotoxicity and apoptosis. Moreover, pretreatment of breast cancer cells with AT-101 and then with TRAIL caused enhancement of the expression levels of DR4 and DR5 in both cancer cell lines, suggesting that these cells were under strong apoptotic stimuli.
  
  
  CONCLUSIONS
  These findings all together, strongly suggest that pretreatment with AT-101 enhances TRAIL-induced death-inducing signaling complex resulting in the engagement of the mitochondrial pathway to apoptosis in breast cancer cells. These promising, preliminary results make AT-101 and TRAIL a novel combination treatment candidate for breast cancer.
authors.affiliation: Section of Molecular Biology, Department of Biology, Faculty of Science and Arts, Celal Bayar University, Muradiye, 45140 Manisa, Turkey.
authors.forename: Asli
authors.initials: A
authors.lastname: Kisim
authors.forename: Harika
authors.initials: H
authors.lastname: Atmaca
authors.forename: Burcu
authors.initials: B
authors.lastname: Cakar
authors.forename: Bulent
authors.initials: B
authors.lastname: Karabulut
authors.forename: Canfeza
authors.initials: C
authors.lastname: Sezgin
authors.forename: Selim
authors.initials: S
authors.lastname: Uzunoglu
authors.forename: Ruchan
authors.initials: R
authors.lastname: Uslu
authors.forename: Burcak
authors.initials: B
authors.lastname: Karaca
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D006072:Gossypol / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D006072:Gossypol; C028178:gossypol acetic acid