Project description:Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of malignant CD5+ B lymphocytes (CLL cells) in the peripheral blood, and their progressive infiltration in lymphoid organs. MMP-9 plays an important role in cell migration and survival, contributes to CLL pathogenesis by proteolytic and non-proteolytic mechanisms and may constitutive a therapeutic target. We used Affimetrix microarray technology to characterize the global gene expression profile of chronic lymphocytic leukemia (CLL) cells upon MMP-9 transfection. The aim was to establish whether MMP-9 regulates gene expression and to identify new therapeutic targets in CLL.
Project description:To study the impact of SF3B1 mutations on alternative splicing and the effect of H3B-8800 splicing modulator in wild type and SF3B1-mutant chronic lymphocytic leukemia cells, we established SF3B1 K700E MEC1 CLL isogenic cell line and carried out RNA deep sequencing in SF3B1 wild type and K700E MEC1 cell lines upon H3B-8800 treatment.
Project description:SF3B1 mutations are recurrent genetic aberrations in chronic lymphocytic leukemia (CLL) that are particularly enriched in the clinically aggressive stereotyped subset #2. To elucidate the effect of SF3B1 mutations on splicing, we performed RNA-sequencing on 100 CLL subset cases, including 35 subset #2 cases. Zooming in on subset #2, we identified 61 differentially expressed splicing events when comparing 17 SF3B1mut to 18 SF3B1wt cases. A key event concerned the inclusion of an alternative exon in BRD9, a BAF chromatin remodeling complex component. We also detected alternative splicing in 5 additional transcripts related to the BAF complex: ZEB1, PLSCR1, PAPD5, DCAF16, and DLST. Long-read RNA-sequencing confirmed these alternative splice transcripts. In conclusion, spliceosome dysregulation caused by mutated SF3B1 leads to multiple splicing events and altered BAF complex function, highlighting a potential novel therapeutic vulnerability in SF3B1mut CLL.
Project description:Acute Myeloid Leukemia (AML) has been associated with somatic mutations in numerous genes; however, the penetrance of these mutations is low. Here we investigate the contribution of alternative splicing as an additional layer of gene dysregulation in AML. By analyzing splicing variations across two patient datasets, we find a consistent set of splicing events that disrupt the coding potential of a subset of AML-associated genes. Importantly, most of these splicing variations are independent of any currently-identified somatic mutations. We have further validated that for EZH2 and ZRSR2 these splicing events reduce the expression of full-length protein. Together these results highlight the contribution of splicing to gene dysregulation and demonstrate that mutation analysis underestimates the burden of functional gene disruption in patient populations.
Project description:Richter syndrome (RS) occurs in up to 15% of patients with chronic lymphocytic leukemia (CLL). While RS, usually represented by the histologic transformation to a diffuse large B-cell lymphoma (DLBCL), is associated with a very poor outcome, especially when clonally related to the pre-existing CLL, mechanisms leading to RS have not been clarified yet. To better understand the pathogenesis of RS, we analyzed a series of cases including: 59 RS, 28 CLL-phase of RS, 315 CLL and 127 de novo DLBCL. RS demonstrated a genomic complexity intermediate between CLL and DLBCL. Cell cycle deregulation via inactivation of TP53 and of CDKN2A was a main mechanism in the histologic transformation from CLL-phase, being present in approximately half of the cases, and affected the outcome of the RS patients. A second major subgroup was characterized by the presence of trisomy 12 and comprised one third of the cases. While RS shared some of the lesions seen in de novo DLBCL, its genomic profile was clearly separate. The CLL-phase preceding RS had not a generalized increase in genomic complexity when compared with untransformed CLL, but it presented clear differences in the frequency of specific genetic lesions. Genomic profiling of Richter-syndrome Chronic Lymphocytic Leukemia
Project description:We analyzed small RNA sequencing data from CD5+/CD19+ B cells of a cohort of indolent and aggressive CLL patients compared with CD19+ B-cells of healthy donors. We identified tsRNA signatures in indolent and aggressive CLL vs. normal B-cells; we also found a drastic dysregulation of the expression of mature tRFs in CLL.