Successful nilotinib therapy in a CML affected patient with A380T, P407S and V468A mutations, and a previous suboptimal cytogenetic response to imatinib

Imatinib mesylate (IM) has shown unprecedented effectiveness in the treatment of Chronic Myeloid Leukemia (CML) patients (pts) in the chronic phase of the disease. However, some pts fail to respond or lose their initial response to IM. The European LeukemiaNet (ELN) published recommendations designed to identify patients responding poorly to imatinib. Here we report a case of a suboptimal cytogenetic responder to IM who had a successful response to the second generation tyrosine kinase inhibitor nilotinib (NIL). According to the ELN criteria, CML pts on IM-therapy might show a suboptimal response either because of failure to achieve a CCyR by 12 months of therapy or because of lack of a MMR after 18 months. The prognostic value of these two types of responders might be very different

BCR-ABL residues interacting with ponatinib are critical to preserve the tumorigenic potential of the oncoprotein

Patients with chronic myeloid leukemia in whom tyrosine kinase inhibitors (TKIs) fail often present mutations in the BCR-ABL catalytic domain. We noticed a lack of substitutions involving 4 amino acids (E286, M318, I360, and D381) that form hydrogen bonds with ponatinib. We therefore introduced mutations in each of these residues, either preserving or altering their physicochemical properties. We found that E286, M318, I360, and D381 are dispensable for ABL and BCR-ABL protein stability but are critical for preserving catalytic activity. Indeed, only a "conservative" I360T substitution retained kinase proficiency and transforming potential. Molecular dynamics simulations of BCR-ABLI360T revealed differences in both helix αC dynamics and protein-correlated motions, consistent with a modified ATP-binding pocket. Nevertheless, this mutant remained sensitive to ponatinib, imatinib, and dasatinib. These results suggest that changes in the 4 BCR-ABL residues described here would be selected against by a lack of kinase activity or by maintained responsiveness to TKIs. Notably, amino acids equivalent to those identified in BCR-ABL are conserved in 51% of human tyrosine kinases. Hence, these residues may represent an appealing target for the design of pharmacological compounds that would inhibit additional oncogenic tyrosine kinases while avoiding the emergence of resistance due to point mutations.This work was supported by an investigator grant to P.V. from Associazione Italiana per la Ricerca sul Cancro (AIRC) and by funding from the Biotechnology and Biological Sciences Research Council (BB/I023291/1 and BB/H018409/1 to AP and FF). P.B. is the recipient of an AIRC - Marie Curie fellowship

Pulmonary Hypertension and Erythropoietin

Numerous uremic patients on hemodialysis have pulmonary hypertension attributable to the presence of arteriovenous fistulas, vascular calcification, and endothelial dysfunction due to alterations in the balance between vasoconstrictive and vasodilatory substances. For these reasons, the effects of recombinant human erythropoietin, a drug widely used in patients on dialysis, on the pulmonary circulation were studied. Some authors maintain that recombinant human erythropoietin has an antihypertensive effect, while others have observed that this hormone induces a reduction in pulmonary arterial pressure due to its vasoactive and stimulatory effects on endothelial and smooth muscle cell precursors

Novel Mechanisms of Tumor Promotion by the Insulin Receptor Isoform A in Triple-Negative Breast Cancer Cells

The insulin receptor isoform A (IR-A) plays an increasingly recognized role in fetal growth and tumor biology in response to circulating insulin and/or locally produced IGF2. This role seems not to be shared by the IR isoform B (IR-B). We aimed to dissect the specific impact of IR isoforms in modulating insulin signaling in triple negative breast cancer (TNBC) cells. We generated murine 4T1 TNBC cells deleted from the endogenous insulin receptor (INSR) gene and expressing comparable levels of either human IR-A or IR-B. We then measured IR isoform-specific in vitro and in vivo biological effects and transcriptome in response to insulin. Overall, the IR-A was more potent than the IR-B in mediating cell migration, invasion, and in vivo tumor growth. Transcriptome analysis showed that approximately 89% of insulin-stimulated transcripts depended solely on the expression of the specific isoform. Notably, in cells overexpressing IR-A, insulin strongly induced genes involved in tumor progression and immune evasion including chemokines and genes related to innate immunity. Conversely, in IR-B overexpressing cells, insulin predominantly induced the expression of genes primarily involved in the regulation of metabolic pathways and, to a lesser extent, tumor growth and angiogenesis

Chk1 Inhibition Restores Inotuzumab Ozogamicin Citotoxicity in CD22-Positive Cells Expressing Mutant p53

Inotuzumab ozogamicin (IO) is an anti-CD22 calicheamicin immunoconjugate that has been recently approved for the treatment of relapsed or refractory B-Acute Lymphoblastic Leukemia (r/r B-ALL). We employed both immortalized and primary cells derived from CD22-positive lymphoproliferative disorders to investigate the signaling pathways contributing to IO sensitivity or resistance. We found that the drug reduced the proliferation rate of CD22-positive cell lines expressing wild-type p53, but was remarkably less effective on cells exhibiting mutant p53. In addition, CD22-positive cells surviving IO were mostly blocked in the G2/M phase of the cell cycle because of Chk1 activation that, in the presence of a wild-type p53 background, led to p21 induction. When we combined IO with the Chk1 inhibitor UCN-01, we successfully abrogated IO-induced G2/M arrest regardless of the underlying p53 status, indicating that the DNA damage response triggered by IO is also modulated by p53-independent mechanisms. To establish a predictive value for p53 in determining IO responsiveness, we expressed mutant p53 in cell lines displaying the wild-type gene and observed an increase in IO IC50 values. Likewise, overexpression of an inducible wild-type p53 in cells natively presenting a mutant protein decreased their IC50 for IO. These results were also confirmed in primary CD22-positive cells derived from B-ALL patients at diagnosis and from patients with r/r B-ALL. Furthermore, co-treatment with IO and UCN-01 significantly increased cell death in primary cells expressing mutant p53. In summary, our findings suggest that p53 status may represent a biomarker predictive of IO efficacy in patients diagnosed with CD22-positive malignancies

SETBP1 induces transcription of a network of development genes by acting as an epigenetic hub

SETBP1 variants occur as somatic mutations in several hematological malignancies such as atypical chronic myeloid leukemia and as de novo germline mutations in the Schinzel-Giedion syndrome. Here we show that SETBP1 binds to gDNA in AT-rich promoter regions, causing activation of gene expression through recruitment of a HCF1/KMT2A/PHF8 epigenetic complex. Deletion of two AT-hooks abrogates the binding of SETBP1 to gDNA and impairs target gene upregulation. Genes controlled by SETBP1 such as MECOM are significantly upregulated in leukemias containing SETBP1 mutations. Gene ontology analysis of deregulated SETBP1 target genes indicates that they are also key controllers of visceral organ development and brain morphogenesis. In line with these findings, in utero brain electroporation of mutated SETBP1 causes impairment of mouse neurogenesis with a profound delay in neuronal migration. In summary, this work unveils a SETBP1 function that directly affects gene transcription and clarifies the mechanism operating in myeloid malignancies and in the Schinzel- Giedion syndrome caused by SETBP1 mutations.Peer reviewe

Integrated Genomic, Functional, and Prognostic Characterization of Atypical Chronic Myeloid Leukemia

Atypical chronic myeloid leukemia (aCML) is a BCR-ABL1-negative clonal disorder, which belongs to the myelodysplastic/myeloproliferative group. This disease is characterized by recurrent somatic mutations in SETBP1, ASXL1 and ETNK1 genes, as well as high genetic heterogeneity, thus posing a great therapeutic challenge. To provide a comprehensive genomic characterization of aCML we applied a high-throughput sequencing strategy to 43 aCML samples, including both whole-exome and RNA-sequencing data. Our dataset identifies ASXL1, SETBP1, and ETNK1 as the most frequently mutated genes with a total of 43.2%, 29.7 and 16.2%, respectively. We characterized the clonal architecture of 7 aCML patients by means of colony assays and targeted resequencing. The results indicate that ETNK1 variants occur early in the clonal evolution history of aCML, while SETBP1 mutations often represent a late event. The presence of actionable mutations conferred both ex vivo and in vivo sensitivity to specific inhibitors with evidence of strong in vitro synergism in case of multiple targeting. In one patient, a clinical response was obtained. Stratification based on RNA-sequencing identified two different populations in terms of overall survival, and differential gene expression analysis identified 38 significantly overexpressed genes in the worse outcome group. Three genes correctly classified patients for overall survival

IRF5 promotes the proliferation of human thyroid cancer cells

Abstract Background Interferon Regulatory Factor 5 is a transcription factor that regulates the expression of genes involved in the response to viral infection and in the stimulation of the immune system. Moreover, multiple studies have demonstrated that it negatively regulates cell growth and oncogenesis, favoring cell differentiation and apoptosis. Thyroid carcinoma represents 98% of all thyroid malignancies and has shown a steady increase in incidence in both the USA and western European countries. Findings We investigated the expression, localization and function of IRF5 in thyroid cancer cells and found that it is highly expressed in both primary and immortalized thyroid carcinomas but not in normal thyrocytes. IRF5 levels were variably modulated by Interferon alpha but IRF5 only localized in the cytoplasmic compartment, thus failing to induce p21 expression as previously reported in different cell models. Furthermore, ectopic IRF5 increased both the proliferation rate and the clonogenic potential of malignant thyroid cells, protecting them from the cytotoxic effects of DNA-damaging agents. These results were directly attributable to IRF5, as demonstrated by the reduction in colony-forming ability of thyroid cancer cells after IRF5 silencing. An IRF5-dependent induction of endogenous B-Raf observed in all thyroid cancer cells might contribute to these unexpected effects. Conclusions These findings suggest that, in thyroid malignancies, IRF5 displays tumor-promoting rather than tumor-suppressor activities.</p