Ikaros Deletions in BCR-ABL-negative Childhood Acute Lymphoblastic Leukemia Are Associated with a Distinct Gene Expression Signature but Do Not Result in Intrinsic Chemoresistance

Autor: Vitanza, Nicholas A., Zaky, Wafik, Blum, Roy, Meyer, Julia A., Wang, Jinhua, Bhatla, Teena, Morrison, Debra J., Raetz, Elizabeth A., Carroll, William L.
Jazyk: angličtina
Rok vydání: 2014
Předmět:
Popis: Ikaros, the product of IKZF1, is a regulator of lymphoid development and polymorphisms in the gene have been associated with the acute lymphoblastic leukemia (ALL). Additionally, IKZF1 deletions and mutations identify high-risk biological subsets of childhood ALL [Georgopoulos et al. Cell 1995;83(2):289-299; Mullighan et al. N Engl J Md 2009;360(5):470-480].To discover the underlying pathways modulated by Ikaros we performed gene expression and gene ontology analysis in IKZF1 deleted primary B-ALL pediatric patient samples. To validate downstream targets we performed qPCR on individual patient samples. We also created IKZF1 knockdown B-ALL cell lines with over 50% reduction of Ikaros, mimicking haplosufficient Ikaros deletions, and again performed qPCR to investigate the downstream targets. Finally, to understand the association of Ikaros deletion with a poor prognosis we challenged our IKZF1 knockdown cell lines with chemotherapy and compared responses to IKZF1 wild-type controls.We report a specific gene expression signature of 735 up-regulated and 473 down-regulated genes in IKZF1 deleted primary B-ALL pediatric patient samples. Gene ontology studies revealed an up-regulation of genes associated with cell adhesion, cytoskeletal regulation, and motility in IKZF deleted patient samples. Validated up-regulated target genes in IKZF1 deleted patient samples included CTNND1 and PVRL2 (P = 0.0003 and P = 0.001), and RAB3IP and SPIB (P = 0.005 and P = 0.032) were down-regulated. In further studies in IKZF1 knockdown cell lines, apoptosis assays showed no significant chemoresistance.IKZF1 knockdown alone does not impart intrinsic chemotherapy resistance suggesting that the association with a poor prognosis may be due to additional lesions, microenvironmental interactions with the bone marrow niche, or other factors.
Databáze: OpenAIRE