@article{Martina Pigazzi_Elena Manara_Silvia Bresolin_Claudia Tregnago_Alessandra Beghin_Emma Baron_Emanuela Giarin_Er-Chieh Cho_Riccardo Masetti_Dinesh S. Rao_Kathleen M. Sakamoto_Giuseppe Basso_2013, place={Pavia, Italy}, title={MicroRNA-34b promoter hypermethylation induces CREB overexpression and contributes to myeloid transformation}, volume={98}, url={https://haematologica.org/article/view/6630}, DOI={10.3324/haematol.2012.070664}, abstractNote={MicroRNA-34b down-regulation in acute myeloid leukemia was previously shown to induce CREB overexpression, thereby causing leukemia proliferation <em>in vitro</em> and <em>in vivo</em>. The role of microRNA-34b and CREB in patients with myeloid malignancies has never been evaluated. We examined microRNA-34b expression and the methylation status of its promoter in cells from patients diagnosed with myeloid malignancies. We used gene expression profiling to identify signatures of myeloid transformation. We established that microRNA-34b has suppressor ability and that CREB has oncogenic potential in primary bone marrow cell cultures and <em>in vivo</em>. MicroRNA-34b was found to be up-regulated in pediatric patients with juvenile myelomonocytic leukemia (n=17) and myelodysplastic syndromes (n=28), but was down-regulated in acute myeloid leukemia patients at diagnosis (n=112). Our results showed that hypermethylation of the microRNA-34b promoter occurred in 66% of cases of acute myeloid leukemia explaining the low microRNA-34b levels and CREB overexpression, whereas preleukemic myelodysplastic syndromes and juvenile myelomonocytic leukemia were not associated with hypermethylation or CREB overexpression. In paired samples taken from the same patients when they had myelodysplastic syndrome and again during the subsequent acute myeloid leukemia, we confirmed microRNA-34b promoter hypermethylation at leukemia onset, with 103 CREB target genes differentially expressed between the two disease stages. This subset of CREB targets was confirmed to associate with high-risk myelodysplastic syndromes in a separate cohort of patients (n=20). Seventy-eight of these 103 CREB targets were also differentially expressed between healthy samples (n=11) and <em>de novo</em> acute myeloid leukemia (n=72). Further, low microRNA-34b and high CREB expression levels induced aberrant myelopoiesis through CREB-dependent pathways <em>in vitro</em> and <em>in vivo</em&gt;. In conclusion, we suggest that microRNA-34b controls CREB expression and contributes to myeloid transformation from both healthy bone marrow and myelodysplastic syndromes. We identified a subset of CREB target genes that represents a novel transcriptional network that may control myeloid transformation.}, number={4}, journal={Haematologica}, author={Martina Pigazzi and Elena Manara and Silvia Bresolin and Claudia Tregnago and Alessandra Beghin and Emma Baron and Emanuela Giarin and Er-Chieh Cho and Riccardo Masetti and Dinesh S. Rao and Kathleen M. Sakamoto and Giuseppe Basso}, year={2013}, month={Mar.}, pages={602-610} }