title: The mixed lineage leukemia (MLL) fusion-associated gene AF4 promotes CD133 transcription.
abstract: The AC133 epitope has been used as a marker for both normal and cancer stem cells from multiple tissue lineages. To identify transcription factors that regulate CD133 expression, we conducted parallel large-scale RNA interference screens in Caco-2 cancer cells that endogenously express CD133 and in engineered HEK293 cells that express CD133 from a heterologous promoter. The transcription factor AF4 was identified following a comparative analysis between the two screens. We then showed that AF4 is a promoter of CD133 transcription in multiple cancer cell lines. Knockdown of AF4 resulted in a dramatic reduction in CD133 transcript levels. Importantly, a subset of pediatric acute lymphoblastic leukemias (ALL) harbor a fusion oncogene results from a chromosomal translocation that juxtaposes the mixed-lineage leukemia (MLL) gene and the AF4 gene. An investigation of the functional role of CD133 in the MLL-AF4-dependent ALL cells revealed that CD133 was required for leukemia cell survival. Together, our findings show AF4-dependent regulation of CD133 expression, which is required for the growth of ALL cells. CD133 may therefore represent a therapeutic target in a subset of cancers.
authors.affiliation: Donnelley Centre and Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Mak
authors.forename: Allison M L
authors.initials: AM
authors.lastname: Nixon
authors.forename: Jason
authors.initials: J
authors.lastname: Moffat
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics*; D015153:Blotting, Western; D018938:Caco-2 Cells; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D015456:Leukemia, Biphenotypic, Acute / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics* / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000235:genetics*; D034622:RNA Interference; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D004268:DNA-Binding Proteins; D006023:Glycoproteins; C497422:KMT2A protein, human; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; C000606023:PROM1 protein, human; D010455:Peptides; D035602:Transcriptional Elongation Factors; D051788:Myeloid-Lymphoid Leukemia Protein; C081449:AFF1 protein, human; D011495:Histone-Lysine N-Methyltransferase