title: Epigenetic inactivation of TWIST2 in acute lymphoblastic leukemia modulates proliferation, cell survival and chemosensitivity.
abstract: BACKGROUND
  Altered regulation of many transcription factors has been shown to be important in the development of leukemia. TWIST2 modulates the activity of a number of important transcription factors and is known to be a regulator of hematopoietic differentiation. Here, we investigated the significance of epigenetic regulation of TWIST2 in the control of cell growth and survival and in response to cytotoxic agents in acute lymphoblastic leukemia.
  
  
  METHODS
  TWIST2 promoter methylation status was assessed quantitatively, by combined bisulfite and restriction analysis (COBRA) and pyrosequencing assays, in multiple types of leukemia and TWIST2 expression was determined by quantitative reverse transcriptase polymerase chain reaction analysis. The functional role of TWIST2 in cell proliferation, survival and response to chemotherapy was assessed in transient and stable expression systems.
  
  
  RESULTS
  We found that TWIST2 was inactivated in more than 50% of cases of childhood and adult acute lymphoblastic leukemia through promoter hypermethylation and that this epigenetic regulation was especially prevalent in RUNX1-ETV6-driven cases. Re-expression of TWIST2 in cell lines resulted in a dramatic reduction in cell growth and induction of apoptosis in the Reh cell line. Furthermore, re-expression of TWIST2 resulted in increased sensitivity to the chemotherapeutic agents etoposide, daunorubicin and dexamethasone and TWIST2 hypermethylation was almost invariably found in relapsed adult acute lymphoblastic leukemia (91% of samples hypermethylated).
  
  
  CONCLUSIONS
  This study suggests a dual role for epigenetic inactivation of TWIST2 in acute lymphoblastic leukemia, initially through altering cell growth and survival properties and subsequently by increasing resistance to chemotherapy.
authors: Crucible Laboratory, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, NE1 3BZ, UK.
authors: Shabnam H
authors: SH
authors: Thathia
authors: Stuart
authors: S
authors: Ferguson
authors: Hannah E
authors: HE
authors: Gautrey
authors: Sanne D
authors: SD
authors: van Otterdijk
authors: Michela
authors: M
authors: Hili
authors: Vikki
authors: V
authors: Rand
authors: Anthony V
authors: AV
authors: Moorman
authors: Stefan
authors: S
authors: Meyer
authors: Robert
authors: R
authors: Brown
authors: Gordon
authors: G
authors: Strathdee
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival / Q000235:genetics; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D015870:Gene Expression; D006801:Humans; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics*; D051879:Twist-Related Protein 1 / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D012097:Repressor Proteins; C486274:TWIST2 protein, human; D051879:Twist-Related Protein 1