title: Interaction of translationally controlled tumor protein with Apaf-1 is involved in the development of chemoresistance in HeLa cells.
abstract: BACKGROUND
  Translationally controlled tumor protein (TCTP), alternatively called fortilin, is believed to be involved in the development of the chemoresistance of tumor cells against anticancer drugs such as etoposide, taxol, and oxaliplatin, the underlying mechanisms of which still remain elusive.
  
  
  METHODS
  Cell death analysis of TCTP-overexpressing HeLa cells was performed following etoposide treatment to assess the mitochondria-dependent apoptosis. Apoptotic pathway was analyzed through measuring the cleavage of epidermal growth factor receptor (EGFR) and phospholipase C-γ (PLC-γ), caspase activation, mitochondrial membrane perturbation, and cytochrome c release by flow cytometry and western blotting. To clarify the role of TCTP in the inhibition of apoptosome, in vitro apoptosome reconstitution and immunoprecipitation was used. Pull-down assay and silver staining using the variants of Apaf-1 protein was applied to identify the domain that is responsible for its interaction with TCTP.
  
  
  RESULTS
  In the present study, we confirmed that adenoviral overexpression of TCTP protects HeLa cells from cell death induced by cytotoxic drugs such as taxol and etoposide. TCTP antagonized the mitochondria-dependent apoptotic pathway following etoposide treatment, including mitochondrial membrane damage and resultant cytochrome c release, activation of caspase-9, and -3, and eventually, the cleavage of EGFR and PLC-γ. More importantly, TCTP interacts with the caspase recruitment domain (CARD) of Apaf-1 and is incorporated into the heptameric Apaf-1 complex, and that C-terminal cleaved TCTP specifically associates with Apaf-1 of apoptosome in apoptosome-forming condition thereby inhibiting the amplification of caspase cascade.
  
  
  CONCLUSIONS
  TCTP protects the cancer cells from etoposide-induced cell death by inhibiting the mitochondria-mediated apoptotic pathway. Interaction of TCTP with Apaf-1 in apoptosome is involved in the molecular mechanism of TCTP-induced chemoresistance. These findings suggest that TCTP may serve as a therapeutic target for chemoresistance in cancer treatment.
authors.forename: Jaehoon
authors.initials: J
authors.lastname: Jung
authors.forename: Hyo Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Jeehye
authors.initials: J
authors.lastname: Maeng
authors.forename: Moonhee
authors.initials: M
authors.lastname: Kim
authors.forename: Dong Hae
authors.initials: DH
authors.lastname: Shin
authors.affiliation: Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea. klyoon@ewha.ac.kr.
authors.forename: Kyunglim
authors.initials: K
authors.lastname: Lee
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D053477:Apoptotic Protease-Activating Factor 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D004843:Epistasis, Genetic; D066246:ErbB Receptors / Q000235:genetics; D005047:Etoposide / Q000494:pharmacology; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D051966:Phospholipase C gamma / Q000235:genetics; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology; D000090324:Tumor Protein, Translationally-Controlled 1
chemical_list: D053477:Apoptotic Protease-Activating Factor 1; D014408:Biomarkers, Tumor; C000715647:TPT1 protein, human; D059005:Topoisomerase II Inhibitors; D000090324:Tumor Protein, Translationally-Controlled 1; D005047:Etoposide; D045304:Cytochromes c; D066246:ErbB Receptors; D051966:Phospholipase C gamma; D053148:Caspase 3; D053453:Caspase 9