title: RUNX1 regulates phosphoinositide 3-kinase/AKT pathway: role in chemotherapy sensitivity in acute megakaryocytic leukemia.
abstract: RUNX1 (AML1) encodes the core binding factor alpha subunit of a heterodimeric transcription factor complex which plays critical roles in normal hematopoiesis. Translocations or down-regulation of RUNX1 have been linked to favorable clinical outcomes in acute leukemias, suggesting that RUNX1 may also play critical roles in chemotherapy responses in acute leukemias; however, the molecular mechanisms remain unclear. The median level of RUNX1b transcripts in Down syndrome (DS) children with acute megakaryocytic leukemia (AMkL) were 4.4-fold (P < .001) lower than that in non-DS AMkL cases. Short hairpin RNA knockdown of RUNX1 in a non-DS AMkL cell line, Meg-01, resulted in significantly increased sensitivity to cytosine arabinoside, accompanied by significantly decreased expression of PIK3CD, which encodes the delta catalytic subunit of the survival kinase, phosphoinositide 3 (PI3)-kinase. Transcriptional regulation of PIK3CD by RUNX1 was further confirmed by chromatin immunoprecipitation and promoter reporter gene assays. Further, a PI3-kinase inhibitor, LY294002, and cytosine arabinoside synergized in antileukemia effects on Meg-01 and primary pediatric AMkL cells. Our results suggest that RUNX1 may play a critical role in chemotherapy response in AMkL by regulating the PI3-kinase/Akt pathway. Thus, the treatment of AMkL may be improved by integrating PI3-kinase or Akt inhibitors into the chemotherapy of this disease.
authors.affiliation: Developmental Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Holly
authors.initials: H
authors.lastname: Edwards
authors.forename: Chengzhi
authors.initials: C
authors.lastname: Xie
authors.forename: Katherine M
authors.initials: KM
authors.lastname: LaFiura
authors.forename: Alan A
authors.initials: AA
authors.lastname: Dombkowski
authors.forename: Steven A
authors.initials: SA
authors.lastname: Buck
authors.forename: Julie L
authors.initials: JL
authors.lastname: Boerner
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Taub
authors.forename: Larry H
authors.initials: LH
authors.lastname: Matherly
authors.forename: Yubin
authors.initials: Y
authors.lastname: Ge
mesh_terms: D002648:Child; D058534:Class I Phosphatidylinositol 3-Kinases; D050676:Core Binding Factor Alpha 2 Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D003561:Cytarabine / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D020014:K562 Cells; D007947:Leukemia, Megakaryoblastic, Acute / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D051058:Oncogene Protein v-akt / Q000235:genetics* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; D034741:RNA, Small Interfering; C493728:RUNX1 protein, human; D003561:Cytarabine; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C486018:PIK3CD protein, human; D051058:Oncogene Protein v-akt