title: Histone deacetylase inhibitor trichostatin a potentiates doxorubicin-induced apoptosis by up-regulating PTEN expression.
abstract: BACKGROUND
  The tumor suppressor gene PTEN is a major negative regulator of the PI3K/Akt cellular survival pathway. Overexpression of PTEN by adenoviral transfection increases doxorubicin-induced apoptosis. Whereas doxorubicin-induced apoptosis can be potentiated by the histone deacetylase (HDAC) inhibitor Trichostatin A (TSA), the mechanisms underlying this process remain unclear. The aim of this work was to investigate whether changes in PTEN expression are involved in TSA/doxorubicin-induced apoptosis.
  
  
  METHODS
  We treated 293 T cells with TSA and doxorubicin, detected apoptosis by using Hoechst 33342 staining, and examined changes of PTEN and Egr-1 expression by quantitative real-time polymerase chain reaction (PCR). Luciferase reporter assay was used to evaluate the promoter activity of PTEN and Western blot and enzyme-linked immunosorbent assay (ELISA) were used to confirm changes in the expression of PTEN. The chromatin immunoprecipitation (ChIP) assay was performed to estimate the acetylation level of PTEN promoter.
  
  
  RESULTS
  Doxorubicin-induced apoptosis was enhanced by TSA, whereas small interfering RNA (siRNA) targeting PTEN inhibited TSA/doxorubicin-induced apoptosis. Also, TSA promoted Egr-1 expression, which is the main transcription factor of PTEN, and this resulted in up-regulation of PTEN expression, which consequently potentiated apoptosis. Moreover, histone acetyltransferase p300 was able to synergistically activate PTEN transcription with Egr-1, implicating the role of histone acetylation in the regulation of PTEN expression.
  
  
  CONCLUSIONS
  TSA promoted doxorubicin-induced apoptosis through a mechanism that involved the stimulation of Egr-1 expression, acetylation of core histones at the PTEN promoter, and consequently induction of PTEN transcription. These findings provide a theoretical basis for the therapeutic application of combined treatment of TSA/doxorubicin for cancer.
authors.affiliation: Institute of Genetics and Cytology, Northeast Normal University, Changchun, Jilin Province, China.
authors.forename: Lina
authors.initials: L
authors.lastname: Pan
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Xiuli
authors.initials: X
authors.lastname: Wang
authors.forename: Liping
authors.initials: L
authors.lastname: Han
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Songyan
authors.initials: S
authors.lastname: Han
authors.forename: Baiqu
authors.initials: B
authors.lastname: Huang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology*; D051766:Early Growth Response Protein 1 / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D047468:Immunoprecipitation; D051059:PTEN Phosphohydrolase / Q000187:drug effects* / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; C012589:trichostatin A; D004317:Doxorubicin; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human