Gene expression profiling on CML patients with Philadelphia translocation.

OBJECTIVE: The use of tyrosine kinase inhibitors (TKIs) and other targeted therapeutics plays a pivotal role in treatment management for individuals diagnosed with chronic myeloid leukemia (CML). However, some patients may experience fewer favorable outcomes and treatment resistance. Our work aims to use whole transcriptome sequencing to evaluate the variations in gene expression patterns among individuals with CML based on their response to TKI therapy. PATIENTS AND METHODS: Ten blood samples were obtained from two groups of patients diagnosed with CML: those at the initial diagnosis stage and those at the recurrence stage. RNA extraction was performed on all samples and used for next-generation sequencing. The data analysis was performed using the DESeq2 R program. RESULTS: In total, 499 genes were identified as having statistically significant differences in expression levels between the two groups. Of these, 122 genes exhibited upregulation, and 377 genes exhibited downregulation. We observed a notable dysregulation in the expression levels of NTRK2 (with a fold change more significant than +5). A significant proportion of the genes that were expressed demonstrated involvement in several biological processes, including the cell cycle, PI3K-AKT signaling system, cellular senescence, oxidative phosphorylation, microRNA in cancer, FOXO signaling pathway, P53 signaling pathway, and other related pathways. CONCLUSIONS: The results demonstrate a correlation between signaling pathways and the development of treatment resistance in patients with CML. These pathways exhibited enhanced efficacy in transmitting signals downstream of the TKI target, BCR-ABL. Several target genes require additional validation in a more extensive cohort study to verify their correlation with TKI resistance. The present research highlights that many BCR-ABL-independent pathways may be correlated with resistance, thus enhancing the prospective therapy options for patients with CML.

Methylation of the suppressor of Cytokine Signaling 1 Gene (SOCS1) in Philadelphia-negative myeloproliferative neoplasms.

OBJECTIVE: Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway activation is initiated by mutations in the JAK2 gene. This activation is in turn, a vital pathogenetic mechanism in myeloproliferative neoplasms (MPNs). However, several factors affect the pathogenesis of MPNs other than the JAK2 gene mutations, such as the downregulation of cytokine signaling (SOCS) proteins, which are potent inhibitors of the JAK/STAT pathway. Therefore, we hypothesized that the regulation of SOCS protein system might be a possible pathogenetic mechanism of MPNs through activating the JAK/STAT pathway. PATIENTS AND METHODS: Our study aimed to investigate the status of the Suppressors of cytokine signaling 1 (SOCS1) in 125 MPNs specimens at the level of mutated points. The acquired mutations, aberrant expression, and/or CpG island hypermethylation of SOCS1 were analyzed among Philadelphia-negative myeloproliferative neoplasm patients. RESULTS: SOCS1 was identified in 20.0% of all patients with Philadelphia-negative myeloproliferative neoplasm. At the diagnosis, the prevalence of methylation was 41.0% for Polycythaemia Vera (PV), 27.7% for Essential Thrombocythaemia (ET), and 6.6% for Primary Myelofibrosis (PMF). The methylation was not detected in 20 healthy adult people. A significant association was found between disease groups (p=.077). The presence of methylated SOCS1 was found to be significantly correlated with age (p=.005), total RBCs count (p=.019), hemoglobin (Hb) concentration (p=.002), and Hematopoietic cell transplant (HCT) (p=.007) in PV patients. However, the presence of methylated SOCS1 was found to be significantly associated with age (p=.012), total RBCs count (p=.022), Hb concentration (p=.024), HCT (p=.033), and platelets count (p=.037) in ET patients. Moreover, the presence of methylated SOCS1 was significantly associated with Hb concentration (p=.046) and HCT (p=.040) in PMF patients. CONCLUSIONS: We concluded that the activation of the JAK/STAT signaling pathway in alternative or with JAK2 mutations leads to SOCS1 hypermethylation, which could represent a potential therapeutic target.

Loss-of-function mutations of Dynamin 2 promote T-ALL by enhancing IL-7 signalling.

Mutations in the DYNAMIN2 (DNM2) gene are frequently detected in human acute T-cell lymphoblastic leukemia (T-ALL), although the mechanisms linking these mutations to disease pathogenesis remain unknown. Using an ENU-based forward genetic screen for mice with erythroid phenotypes, we identified a heterozygous mouse line carrying a mutation in the GTPase domain of Dnm2 (Dnm2V265G) that induced a microcytic anemia. In vitro assays using the V265G mutant demonstrated loss of GTPase activity and impaired endocytosis that was comparable to other DNM2 mutants identified in human T-ALL. To determine the effects of DNM2 mutations in T-ALL, we bred the Dnm2V265G mice with the Lmo2 transgenic mouse model of T-ALL. Heterozygous Dnm2 mutants lacking the Lmo2 transgene displayed normal T-cell development, and did not develop T-ALL. In contrast, compound heterozygotes displayed an accelerated onset of T-ALL compared with mice carrying the Lmo2 oncogene alone. The leukemias from these mice exhibited a more immature immunophenotype and an expansion in leukemic stem cell numbers. Mechanistically, the Dnm2 mutation impaired clathrin-mediated endocytosis of the interleukin (IL)-7 receptor resulting in increased receptor density on the surface of leukemic stem cells. These findings suggest that DNM2 mutations cooperate with T-cell oncogenes by enhancing IL-7 signalling.

Hhex regulates Kit to promote radioresistance of self-renewing thymocytes in Lmo2-transgenic mice.

Lmo2 is an oncogenic transcription factor that is frequently overexpressed in T-cell acute leukemias, in particular poor prognosis early T-cell precursor-like (ETP-) acute lymphoblastic leukemia (ALL). The primary effect of Lmo2 is to cause self-renewal of developing CD4(-)CD8(-) (double negative, DN) T cells in the thymus, leading to serially transplantable thymocytes that eventually give rise to leukemia. These self-renewing thymocytes are intrinsically radioresistant implying that they may be a source of leukemia relapse after therapy. The homeobox transcription factor, Hhex, is highly upregulated in Lmo2-transgenic thymocytes and can phenocopy Lmo2 in inducing thymocyte self-renewal, implying that Hhex may be a key component of the Lmo2-induced self-renewal program. To test this, we conditionally deleted Hhex in the thymi of Lmo2-transgenic mice. Surprisingly, this did not prevent accumulation of DN thymocytes, nor alter the rate of overt leukemia development. However, deletion of Hhex abolished the transplantation capacity of Lmo2-transgenic thymocytes and overcame their radioresistance. We found that Hhex regulates Kit expression in Lmo2-transgenic thymocytes and that abrogation of Kit signaling phenocopied loss of Hhex in abolishing the transplantation capacity and radioresistance of these cells. Thus, targeting the Kit signaling pathway may facilitate the eradication of leukemia-initiating cells in immature T-cell leukemias in which it is expressed.