Chronic myeloid leukemia

IL-12-Dependent enhancement of CTL response to weak class I-restricted peptide immunogens requires coimmunization with T helper cell immunogens

The effect of in vivo administration of rmIL-12 on the CTL response to immunization with a weakly immunogenic class I-restricted peptide emulsified in incomplete Freund's adjuvant was investigated. In the absence of IL-12, peptide-specific CTL responses were significantly greater following coimmunization with class I-restricted peptide and T helper cell antigens than following immunization with the class I-restricted peptide alone. IL-12-dependent enhancement of the CTL response to peptide immunization was demonstrated in the presence of, but not in the absence of, coimmunization with T helper cell antigen. These findings indicate that IL-12 enhancement of the CTL response to weak class I-restricted immunogens is T helper cell dependent. Treatment with rmIL-12 also enhanced the CTL response to immunization with cDNA encoding both CTL and T helper cell epitopes. These findings are relevant to the design of vaccines containing tumor-associated class I-restricted peptides currently being tested as an immunotherapy for cancer patients.

Regulated expression of P210 Bcr-Abl during embryonic stem cell differentiation stimulates multipotential progenitor expansion and myeloid cell fate

P210 Bcr-Abl is an activated tyrosine kinase oncogene encoded by the Philadelphia chromosome associated with human chronic myelogenous leukemia (CML). The disease represents a clonal disorder arising in the pluripotent hematopoietic stem cell. During the chronic phase, patients present with a dramatic expansion of myeloid cells and a mild anemia. Retroviral gene transfer and transgenic expression in rodents have demonstrated the ability of Bcr-Abl to induce various types of leukemia. However, study of human CML or rodent models has not determined the direct and immediate effects of Bcr-Abl on hematopoietic cells from those requiring secondary genetic or epigenetic changes selected during the pathogenic process. We utilized tetracycline-regulated expression of Bcr-Abl from a promoter engineered for robust expression in primitive stem cells through multilineage blood cell development in combination with the in vitro differentiation of embryonal stem cells into hematopoietic elements. Our results demonstrate that Bcr-Abl expression alone is sufficient to increase the number of multipotent and myeloid lineage committed progenitors in a dose-dependent manner while suppressing the development of committed erythroid progenitors. These effects are reversible upon extinguishing Bcr-Abl expression. These findings are consistent with Bcr-Abl being the sole genetic change needed for the establishment of the chronic phase of CML and provide a powerful system for the analysis of any genetic change that alters cell growth and lineage choices of the hematopoietic stem cell.

A nuclear tyrosine phosphorylation circuit: c-Jun as an activator and substrate of c-Abl and JNK

The nuclear function of the c-Abl tyrosine kinase is not well understood. In order to identify nuclear substrates of Abl, we constructed a constitutively active and nuclear form of the protein. We found that active nuclear Abl efficiently phosphorylate c-Jun, a transcription factor not previously known to be tyrosine phosphorylated. After phosphorylation of c-Jun by Abl on Tyr170, both proteins interacted via the SH2 domain of Abl. Surprisingly, elevated levels of c-Jun activated nuclear Abl, resulting in activation of the JNK serine/threonine kinase. This phosphorylation circuit generates nuclear tyrosine phosphorylation and represents a reversal of previously known signalling models.

The Tyrosine Kinase Abl-Related Gene ARG Is Fused toETV6 in an AML-M4Eo Patient With a t(1;12)(q25;p13): Molecular Cloning of Both Reciprocal Transcripts

The Ets variant gene 6 (ETV6/TEL) gene is rearranged in the majority of patients with 12p13 translocations fused to a number of different partners. We present here a case of acute myeloid leukemia M4 with eosinophilia (AML-M4Eo) positive for the CBFb/MYH11 rearrangement and carrying a t(1;12)(q25;p13) that involves the ETV6 gene at 12p13. By 3′rapid amplification of cDNA ends-polymerase chain reaction (3′RACE-PCR), a novel fusion transcript was identified between the ETV6 and the Abelson-related gene (ARG) at 1q25, resulting in a chimeric protein consisting of the HLH oligomerization domain of ETV6 and the SH2, SH3, and protein tyrosine kinase (PTK) domains of ARG. The reciprocal transcript ARG-ETV6 was also detected in the patient RNA by reverse transcriptase-polymerase chain reaction (RT-PCR), although at a lower expression level. The ARG gene encodes for a nonreceptor tyrosine kinase characterized by high homology with c-Abl in the TK, SH2, and SH3 domains. This is the first report on ARGinvolvement in a human malignancy.

The Tyrosine Kinase Abl-Related Gene ARG Is Fused toETV6 in an AML-M4Eo Patient With a t(1;12)(q25;p13): Molecular Cloning of Both Reciprocal Transcripts

The Ets variant gene 6 (ETV6/TEL) gene is rearranged in the majority of patients with 12p13 translocations fused to a number of different partners. We present here a case of acute myeloid leukemia M4 with eosinophilia (AML-M4Eo) positive for the CBFb/MYH11 rearrangement and carrying a t(1;12)(q25;p13) that involves the ETV6 gene at 12p13. By 3′rapid amplification of cDNA ends-polymerase chain reaction (3′RACE-PCR), a novel fusion transcript was identified between the ETV6 and the Abelson-related gene (ARG) at 1q25, resulting in a chimeric protein consisting of the HLH oligomerization domain of ETV6 and the SH2, SH3, and protein tyrosine kinase (PTK) domains of ARG. The reciprocal transcript ARG-ETV6 was also detected in the patient RNA by reverse transcriptase-polymerase chain reaction (RT-PCR), although at a lower expression level. The ARG gene encodes for a nonreceptor tyrosine kinase characterized by high homology with c-Abl in the TK, SH2, and SH3 domains. This is the first report on ARGinvolvement in a human malignancy.

Bcr-Abl with an SH3 deletion retains the ability To induce a myeloproliferative disease in mice, yet c-Abl activated by an SH3 deletion induces only lymphoid malignancy

The bcr-abl oncogene plays a critical role in the pathogenesis of chronic myelogenous leukemia (CML). The fusion of Bcr sequences to Abl constitutively activates the Abl protein tyrosine kinase. We have recently shown that expression of Bcr-Abl in bone marrow cells by retroviral transduction efficiently induces in mice a myeloproliferative disease resembling human CML and that Abl kinase activity is essential for Bcr-Abl to induce a CML-like myeloproliferative disease. However, it is not known if activation of the Abl kinase alone is sufficient to induce a myeloproliferative disease. In this study, we examined the role of the Abl SH3 domain of Bcr-Abl in induction of myeloproliferative disease and tested whether c-Abl activated by SH3 deletion can induce a CML-like disease. We found that Bcr-Abl with an Abl SH3 deletion still induced a CML-like disease in mice. In contrast, c-Abl activated by SH3 deletion induced only lymphoid malignancies in mice and did not stimulate the growth of myeloid colonies from 5-fluorouracil-treated bone marrow cells in vitro. These results indicate that Bcr sequences in Bcr-Abl play additional roles in inducing myeloproliferative disease beyond simply activating the Abl kinase domain and that functions of the Abl SH3 domain are either not required or redundant in Bcr-Abl-induced myeloproliferative disease. The results also suggest that the type of hematological neoplasm induced by an abl oncogene is influenced not only by what type of hematopoietic cells the oncogene is targeted into but also by the intrinsic oncogenic properties of the particular abl oncogene. In addition, we found that DeltaSH3 c-Abl induced less activation of Akt and STAT5 than did Bcr-Abl, suggesting that activation of these pathways plays a critical role in inducing a CML-like disease.