Cristobal, I. (Ion)
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- Overexpression of SET is a recurrent event associated with poor outcome and contributes to protein phosphatase 2A inhibition in acute myeloid leukemia(Ferrata Storti Foundation, 2012) Cristobal, I. (Ion); Garcia-Orti, L. (Laura); Garcia-Sanchez, M.A. (María A.); Cortes-Lavaud, X. (Xabier); Calasanz-Abinzano, M.J. (Maria Jose); Odero, M.D. (Maria Dolores); Cirauqui, C. (Cristina)BACKGROUND: Protein phosphatase 2A is a novel potential therapeutic target in several types of chronic and acute leukemia, and its inhibition is a common event in acute myeloid leukemia. Upregulation of SET is essential to inhibit protein phosphatase 2A in chronic myeloid leukemia, but its importance in acute myeloid leukemia has not yet been explored. DESIGN AND METHODS: We quantified SET expression by real time reverse transcriptase polymerase chain reaction in 214 acute myeloid leukemia patients at diagnosis. Western blot was performed in acute myeloid leukemia cell lines and in 16 patients' samples. We studied the effect of SET using cell viability assays. Bioinformatics analysis of the SET promoter, chromatin immunoprecipitation, and luciferase assays were performed to evaluate the transcriptional regulation of SET. RESULTS: SET overexpression was found in 60/214 patients, for a prevalence of 28%. Patients with SET overexpression had worse overall survival (P<0.01) and event-free survival (P<0.01). Deregulation of SET was confirmed by western blot in both cell lines and patients' samples. Functional analysis showed that SET promotes proliferation, and restores cell viability after protein phosphatase 2A overexpression. We identified EVI1 overexpression as a mechanism involved in SET deregulation in acute myeloid leukemia cells. CONCLUSIONS: These findings suggest that SET overexpression is a key mechanism in the inhibition of PP2A in acute myeloid leukemia, and that EVI1 overexpression contributes to the deregulation of SET. Furthermore, SET overexpression is associated with a poor outcome in acute myeloid leukemia, and it can be used to identify a subgroup of patients who could benefit from future treatments based on PP2A activators.
- Integration of SNP and mRNA arrays with microRNA profiling reveals that MiR-370 is upregulated and targets NF1 in acute myeloid leukemia(2012) Cristobal, I. (Ion); Garcia-Orti, L. (Laura); Castello-Cros, R. (Remedios); Guruceaga, E. (Elizabeth); Marcotegui, N. (Nerea); Calasanz-Abinzano, M.J. (Maria Jose); Odero, M.D. (Maria Dolores); Cirauqui, C. (Cristina)Abstract Background: Deregulated miRNA expression plays a crucial role in carcinogenesis. Recent studies show different mechanisms leading to miRNA deregulation in cancer; however, alterations affecting miRNAs by DNA copy number variations (CNV) remain poorly studied. Results: Our integrative analysis including data from high resolution SNPs arrays, mRNA expression arrays, and miRNAs expression profiles in 16 myeloid cell lines highlights that CNV are alternative mechanisms to deregulate the expression of miRNAs in acute myeloid leukemia (AML), and represent a novel approach to identify novel candidate genes involved in AML. We found association between the expression levels of 19 miRNAs and CNVs affecting their loci. Functional analysis showed that NF1 is a direct target of miR-370, and that overexpression of miR-370 has similar effects that NF1 inactivation, increasing proliferation and colony formation in AML cells. Moreover, real time RT-PCR showed that NF1 downregulation is a recurrent event in AML (30.8%), and western blot analysis confirmed this result. MiR-370 overexpression and deletions affecting the NF1 locus were identified as alternative mechanisms to downregulate NF1. Conclusions: NF1 downregulation is a common event in AML, and both deletions in the NF1 locus and overexpression of miR-370 are alternative mechanisms to downregulate NF1 in this disease. Our results suggest a leukemogenic role of miR- 370 through NF1 downregulation in AML cells. Since NF1 deficiency leads to RAS activation, patients with AML and overexpression of miR-370 may potentially benefit from additional treatment with either RAS or mTOR inhibitors.
- Papel de la proteína fosfatasa 2A (PP2A) y su inhibidor endógeno SET en la leucemia mieloide aguda(Servicio de Publicaciones, Universidad de Navarra, 2013-01-08) Cristobal, I. (Ion); Odero, M.D. (Maria Dolores)Papel de la proteína fosfatasa 2A (PP2A) y su inhibidor endógeno SET en la leucemia mieloide aguda