The translocation t(9;22)(q34;q11), known as Philadelphia chromosome (Ph1) or its molecular equivalent the expression of BCR-ABL-mRNA, is one of the most striking and well-characterized cytogenetic abnormalities in leukemia.
Several methods to model human Ph+ leukemia in laboratory mice are available, including propagation of BCR/ABL-expressing cells in mice, xenotransplantation of primary Ph+ leukemia cells into immunodeficient mice, BCR/ABL transgenic mice, and BCR/ABL retroviral bone marrow transduction and transplantation.
Leukemias expressing the constitutively activated tyrosine kinases (TK) BCR-ABL1 and FLT3/ITD activate signaling pathways that increase genomic instability through generation of reactive oxygen species (ROS), DNA double-strand breaks (DSB), and error-prone repair.
Furthermore, the BCR-ABL oncogene, which induces Slug expression in leukaemic cells, did not induce leukaemia in Slug-deficient mice, implicating Slug in BCR-ABL leukaemogenesis in vivo.
The bcr-abl oncoprotein (P210 or P185), the product of the fused bcr-abl gene produced by the Ph, is known to be the major factor in initiation and maintenance of the leukemic state in these types of leukemias.
To gain insight into factors that influence the action of a prototypical targeted drug, we studied the action of imatinib (STI-571, Gleevec) against murine cells and leukemias expressing BCR-ABL, an imatinib target and the initiating oncogene for human chronic myelogenous leukemia (CML).
These findings identify AID as a BCR-ABL1-induced mutator in Ph(+) ALL cells, which may be relevant with respect to the particularly unfavorable prognosis of this leukemia subset.
Treatment of leukemia cell lines harboring wild-type or mutant Bcr-Abl with 10 microM PEITC resulted in an elevated ROS stress and a redox-mediated degradation of the BCR-ABL protein, leading to massive death of the leukemia cells.
Imatinib is a tyrosine kinase inhibitor for BCR-ABL1 in Philadelphia chromosome-positive (Ph+) leukemia, and development of resistance due to kinase domain mutation is an important issue.
The present study indicates that herbimycin A is a beneficial agent for the investigation of the role of the bcr-abl gene in Ph1-positive leukemias and further suggests that the development of agents inhibiting the bcr-abl gene product may offer a new therapeutic potential for Ph1-positive leukemias.
In BCR/ABL- or BCR/ABL-T315I-driven murine leukemia as well as in xenograft models of primary Ph+ leukemia harboring the T315I, PF-114 significantly prolonged survival to a similar extent as ponatinib.
The present study suggests that formation of the chimeric bcr-abl gene and its genetic products may play an important role in the development of leukemia in either radiation-induced or de novo CML.
The significance of the finding that a part of the SH3 region of ABL protein is missing in some Philadelphia chromosome-positive leukemias is discussed in reference to the cases reported previously.
Hemin treatment also decreased the sensitivity of cells to four anthracyclins, daunorubicin, idarubicin, doxorubicin, and mitoxantrone, in BCR/ABL-negative leukemia U937 and THP-1 cells, as well as in KCL22 cells.
The introduction of kinase inhibitors in cancer medicine has transformed chronic myeloid leukemia from a fatal disease into a leukemia subtype with a favorable prognosis by interfering with the constitutively active kinase BCR-ABL.
In conclusion, these results suggest that BCR-ABL regulates cell cycle in CML cells at least in part by inducing proteasome-mediated degradation of the cell cycle inhibitor p27(Kip1) and provide a rationale for the use of inhibitors of the proteasome in patients with BCR-ABLleukemias.
The product of the Philadelphia chromosome (Ph) translocation, the BCR/ABL oncogene, exists in three principal forms (P190, P210, and P230 BCR/ABL) that are found in distinct forms of Ph-positive leukemia, suggesting the three proteins have different leukemogenic activity.
As an oral, nontoxic compound with a mechanism of action distinct from that of ABL tyrosine kinase inhibition, FTI SCH66336 shows promise for the treatment of BCR/ABL-induced leukemia.