MicroRNAs involvement in fludarabine refractory chronic lymphocytic leukemia.

BACKGROUND: Fludarabine, is one of the most active single agents in the treatment of chronic lymphocytic leukemia (CLL). Over time, however, virtually all CLL patients become fludarabine-refractory. To elucidate whether microRNAs are involved in the development of fludarabine resistance, we analyzed the expression of 723 human miRNAs before and 5-days after fludarabine mono-therapy in 17 CLL patients which were classified as responder or refractory to fludarabine treatment based on NCI criteria. RESULTS: By comparing the expression profiles of these two groups of patients, we identified a microRNA signature able to distinguish refractory from sensitive CLLs. The expression of some microRNAs was also able to predict fludarabine resistance of 12 independent CLL patients. Among the identified microRNAs, miR-148a, miR-222 and miR-21 exhibited a significantly higher expression in non-responder patients either before and after fludarabine treatment. After performing messenger RNA expression profile of the same patients, the activation of p53-responsive genes was detected in fludarabine responsive cases only, therefore suggesting a possible mechanism linked to microRNA deregulation in non-responder patients. Importantly, inhibition of miR-21 and miR-222 by anti-miRNA oligonucleotides induced a significant increase in caspase activity in fludarabine-treated p53-mutant MEG-01 cells, suggesting that miR-21 and miR-222 up-regulation may be involved in the establishment of fludarabine resistance. CONCLUSIONS: This is the first report that reveals the existence of a microRNA profile that differentiate refractory and sensitive CLLs, either before and after fludarabine mono-therapy. A p53 dysfunctional pathway emerged in refractory CLLs and could contribute in explaining the observed miRNA profile. Moreover, this work indicates that specific microRNAs can be used to predict fludarabine resistance and may potentially be used as therapeutic targets, therefore establishing an important starting point for future studies.

Chromosome 14q32 translocations involving the immunoglobulin heavy chain locus in chronic lymphocytic leukaemia identify a disease subset with poor prognosis.

Immunophenotypic studies, fluorescence in situ hybridization (FISH) and conventional karyotyping were used to define the clinicobiological significance of 14q32 translocations involving the immunoglobulin gene locus (14q32/IGH) in 252 chronic lymphocytic leukaemia (CLL) patients. The following regions were studied: 13q14, centromere 12, 6q21; 11q22/ATM; 17p13/TP53, 14q32/IGH. Patients were classified as group 1 (favourable, i.e. 13q-single or normal), group 2 (intermediate risk, i.e. +12, 6q-, 1-2 anomalies), group 3 (unfavourable, i.e. 17p-, 11q-, complex karyotype), or group 4 (14q32/IGH translocation). Endpoints were treatment-free survival (TFS) and overall survival (OS). One hundred and ten patients were included in group 1, 99 in group 2, 25 in group 3 and 18 in group 4. 14q32/IGH translocation partners were identified in eight cases (BCL2 in five cases, BCL11A, CCND3 and CDK6 in one case each). group 4 showed shorter TFS versus groups 2 and 1 (25% patients treated at 2 months vs. 12 (P = 0.02) and 20 months (P = 0.002), respectively) and shorter OS (25% patients dead at 18 months versus 50 (P = 0.0003) and >60 months (P < 0.0001) respectively. The 14q32/IGH translocation maintained prognostic significance at multivariate analysis on TFS (P = 0.025) and OS (P < 0.001), along with advanced stage and CD38+. These findings show that the 14q32/IGH translocation predicts for an unfavourable outcome in CLL and that this cytogenetic subset might be included as a separate entity in a hierarchical cytogenetic classification of CLL.

Abnormalities of chromosomes 1p34-36, 4p16, 4q35, 9q11-32 and +7 represent novel recurrent cytogenetic rearrangements in chronic lymphocytic leukemia.

Karyotypes were studied in over 250 cases of CLL seen at our Institution and 12 cases with a previously undescribed chromosome abnormality were identified. Cytogenetic and clinicobiological features in these patients are described. Fluorescence in situ hybridization using probes for the detection of +12 and deletions of 13q14, 17p13, and 11q22-23 was performed. Hematologic and clinical data were reviewed and a review of the literature was performed. Twelve patients were found carrying the following aberrations in the stemline: abnormalities at 1p34 (n = 2), 4p16 (n = 2), 4q35 (n = 2), 9q11-32 (n = 4) and +7 (n = 2). Trisomy 12 was found in 3 cases, whereas no case carried 13q-, 11q-, 17p-. Our data showed that (i) aberrations involving 1p34 and 4p16 as isolated chromosome anomalies were preferentially associated with early stage disease; (ii) 4q35 anomalies were associated with a relatively aggressive disease, atypical morphology and with monoclonal gammopathy; (iii) rearrangements of 9q were characterized by atypical morphology and aggressive disease with splenic involvement; (iv) +7 be may associated with +12. 1p34-36; 4p16; 4q35; 9q and chromosome 7 represent novel recurrent rearranged sites in CLL, with a 0.5-3% incidence. Transformation in these patients seemingly occured through a cytogenetic route not involving the classical CLL-associated chromosome regions. These chromosome rearrangements may be associated with peculiar hematologic features.

Mobilization of endothelial progenitor cells in patients with hematological malignancies after treatment with filgrastim and chemotherapy for autologous transplantation.

In recent years, endothelial progenitor cells (EPCs), gave rise to increasing interest because of their possible use as a therapeutic tool in the treatment of vascular lesions in ischemic tissues or as a target for anti neoplastic therapy. It has been shown that several drugs can increase the number of EPCs into the peripheral blood (PB). However, there is insufficient data concerning the mobilization and collection of EPCs during CD34+ cell mobilization. In this study, we have evaluated EPC mobilization and collection in a series of 47 patients affected by lymphoid neoplasms [31 non Hodgkin lymphoma and 16 multiple myeloma] undergoing CD34+ cell mobilization with cyclophosphamide (4000 mg/m2) and Filgrastim (5 microg/kg). PB EPCs identified by flow cytometry as CD34+/VEGFR2+/CD133+ cells showed a peak on day +10. This peak paralleled that of PB CD34+/CD45+ cells. A direct correlation was observed between CD34+ and CD34+/VEGFR2+/CD133+ cells (r = 0.99 P < 0.0001). An average of 23.7 x 10e6 CD34+/VEGFR2+ CD133+ cells have been collected (range 12.1-41.76 x 10e6). These findings showed that in hematological diseases, cyclophosphamide in combination with filgrastim allows the mobilization and collection of large numbers of EPCs which may be used for reparative medicine studies in these patients.

Neoplastic circulating endothelial cells in multiple myeloma with 13q14 deletion.

In multiple myeloma (MM), circulating endothelial cells (CECs) represent a vascular marker of angiogenesis and may reflect tumor mass. In this report, we showed that, in 5 MM patients with 13q14 deletion, CECs carried the same chromosome aberration as the neoplastic plasma cells (11%-32% of CECs with 13q14 deletion). Most of the CECs displayed immunophenotypic features of endothelial progenitor cells as they expressed CD133, a marker gradually lost during endothelial differentiation and absent on mature endothelial cells. To the contrary, in 3 patients with monoclonal gammopathy of undetermined significance and 13q14 deletion, CECs were cytogenetically normal and had a mature immunophenotype. In MM CECs, immunoglobulin genes were clonally rearranged. These findings suggest a possible origin of CECs from a common hemangioblast precursor that can give rise to both plasma cells and endothelial cells and point to a direct contribution of MM-derived CECs to tumor vasculogenesis and possibly to the spreading and progression of the disease.

CXCR-4 expression on bone marrow CD34+ cells prior to mobilization can predict mobilization adequacy in patients with hematologic malignancies.

To investigate the mechanisms of mobilization and of the factors implicated in the homing of progenitors and possibly understand the reasons for unpredicted mobilization failure, we analyzed CXCR-4 (CD184) expression on bone marrow (BM) CD34+ cells prior to peripheral blood stem cell (PBSC) mobilization in 24 patients affected by hematologic malignancies (non-Hodgkin lymphoma, multiple myeloma, and acute myeloid leukemia). We wanted to determine whether the level of CXCR-4 expressed by hematopoietic stem cells could influence mobilization process and therefore could be considered a predictive factor for mobilization adequacy. These data were also compared with stromal cell function as assessed by colony forming unit-fibroblast (CFU-F) and CFU endothelial cells (CFU-En) assays and stromal layer confluence capacity exhibited by patients' BM cells. In this study, we also compared CXCR-4 expression on CD34+ cells from different sources and at different migration stages specifically bone marrow (BM), steady state peripheral blood (SSPB), fetal cord blood (FCB), cord blood (CB), and mobilized PBSC. Seven (29%) of the 24 patients undergoing mobilization failed to achieve an adequate number of CD34+ stem cells (5 x 10(6)/kg CD34+ cells) and showed a very high expression frequency of CXCR-4 on BM CD34(+) stem cells (mean number of positive cells, 97%) investigated before the mobilization regimen. We also found that high expression intensity per cell for CXCR-4 was associated with lower amounts of mobilized CD34+ cells whereas those patients (17 out of 24 patients, 71%) with lower expression intensity per cell of CD184 on BM CD34+ cells prior to mobilization harvested at least 5 x 10(6)/kg CD34+ cells. Setting a cut off of 5 x 10(6)/kg CD34+ cells harvested, patients mobilizing less had a mean value of 97% CD34+ cells expressing CXCR-4 with a relative mean channel fluorescence of 458 whereas patients mobilizing more than 5 x 10(6)/kg CD34+ progenitors showed a mean value of 59.8% CD34+/CXCR4+ cells with a relative mean channel fluorescence value of 305. Interestingly, in the poor mobilizers group, the marrow stromal microenvironment was found to be more severely damaged in comparison with that of good mobilizers. The comparative analysis of CXCR-4 expression showed no difference in percentage values between steady-state PB (87.4%) and BM (85.1%) stem cells whereas mobilized CD34+ stem cells have a lower expression frequency of CXCR-4 (71.6%) compared to that of progenitors from other sources. Fetal blood CD34+ stem cells had the lowest mean expression frequency of CD184 antigen (36.3%), while CB cells had the highest (94.8%). In conclusion, this study provides evidence that monitoring CXCR-4 CD34 double positive cells before mobilization can be regarded as a predictive factor for mobilization outcome, giving us directional cues for the choice of the best stem cell mobilization regimens.