Oncohematology

MicroRNAs and cancer laboratory

Our laboratory demonstrated that

A microRNA can be regulated in the same cell in an allelic-specific way.

We demonstrated that the region surrounding a rare SNP upstream of the miR-15a/16-1 cluster, a key gene in the pathogenesis of chronic lymphocytic leukemia functions as an activator of transcription by RNA polymerase III (RPIII). This regulation of the miR-15a/16- cluster is independent of the DLEU2 host gene, which is transcribed monoallelically by RPII. Our data indicate that usually, one allele of miR-15a/16-1 is transcribed by RNAPII, the other one by RNAPIII. In CLL patients harboring 13q14 deletions, exclusive RPIII-driven transcription of the cluster occurred as a consequence of loss of the RPII-regulated allele and correlated with high expression of the poor prognostic marker ZAP70 (P=0.019). This is a novel biological process, characterized by double allele-specific transcriptional regulation of the miR-15a/16-1 locus by alternative mechanisms. Differential usage of these mechanisms may influence the outcome of patients.

A microRNA can change its function during the progression of cancer.

Our laboratory shown that miR-155 contributes to induce aneuploidy at the early stages of cell transformation by targeting proteins for the correct chromosome alignment during cellular mitosis, such has BUB1. However, in the advanced stages of in vitro fibroblasts transformation and chronic lymphatic leukemia, the expression of BUB1 is restored to maintain the survival of aneuploid clones. An RNA binding protein inhibits the targeting of the miR-155 to BUB1, restoring its expression and supporting steps of selection and expansion of the most fitting leukemic clones.

The action of a microRNA on the specific targets is strikingly associated with the surrounding environment

The clinical progression of B-cell CLL is associated with immune cell dysfunction and a sharp decrease in miR-181b, which promotes the programmed death of CLL cells.

We have shown that activated CD4+T cells increase miR-181b expression in the B-CLL through CD40-CD40L signaling, which improves maturation and the activity of cytotoxic T cells and, consequently, the apoptotic response of B-CLL cells. This phenomenon is due, at least in part, to miR-181b-induced depletion of IL10, which is a strong immune response inhibitor in CLL. In vivo experiments in a model of immunocompromised mice confirmed that miR-181b induces the CLL cell death only when the immune system with functional T cells is restored. This suggests that stimuli from T cells are indispensable to allow the CLL cell death miR-181b mediated.

Activities and research lines:

Our group is involved in cellular manipulation in the setting of allogeneic stem cell transplantation. Experimental and clinical models were developed along decades.

• In the last years we focused our attention on the use of T regulatory cells (Tregs) in the setting of haploidentical stem cell transplantation. In particular, we used for the first time in humans Tregs to successfully prevent graft-versus-host-disease (GvHD) without impairing Tcon-mediated graft-versus-leukemia (GvL) effect. Our present goal will be the use of in vitro expanded Tregs obtained with an automated system, in order to improve the clinical results. The collaboration with other italian bone marrow transplantation centers will allow the rapid use of this new platform. The research group also deals with the mechanisms of action of Tregs cells. Moreover the scientific activity focuses on the search for new GvHD targets such as NOTCH1.
• We have strong expertise in clinical harvest, immunomagnetic separation and extended manipulation of T cells. As a consequence, our project will be focused on CAR lymphocytes development. In particular, the project concerns the production of “home made” CAR-T. The CAR-NK development platform will also be activated. The target for both CAR-T and CAR-NK will be in the first part of the project B-cell malignancies (ALL-B; NHL; CLL). Novel target for AML will be also developed. A strong link with the Hematology Clinical Unit is the key to rapidly obtain pre-clinical results.

Our group is also involved in the study of the role of NOTCH1 in Chronic Lymphatic Leukemia (CLL).

• We showed NOTCH1 is overexpressed  in CLL. We have also discovered the underline mutation that sustains  NOTCH-1 expression. NOTCH-1 mutation is a new negative prognostic marker in CLL. NOTCH1 pathogenetic role  in CLL and its potential role as a new therapeutic target in CLL is under investigation.