BACKGROUND In 5%-10% of patients with of chronic myelogenous leukemia (CML), the Philadelphia chromosome (Ph) is not identified, despite the presence of the associated BCR-ABL molecular abnormality (Ph-negative, BCR-ABL-positive CML) because of sub-microscopic rearrangements. PATIENTS AND METHODS Six patients with Ph-negative, BCR-ABL-positive CML were investigated. The Ph chromosome detectio...

Inhibition of BCR-ABL tyrosine kinase with imatinib represents a major breakthrough in the treatment of patients with chronic myeloid leukemia (CML). However, resistance to imatinib develops frequently, particularly in late-stage disease. To identify new cellular BCR-ABL downstream targets, we analyzed differences in global protein expression in BCR-ABL-positive K562 cells treated with or witho...

The Bcr-Abl oncogene, found in Philadelphia chromosome-positive myelogenous leukemia (CML), activates Ras and triggers the stress-activated protein kinase (SAPK or Jun NH2-terminal kinase [JNK]) pathway. Interruption of Ras or SAPK activation dramatically reduces Bcr-Abl-mediated transformation. Here, we report that Bcr-Abl through a Ras-dependent pathway signals the serine/threonine protein ki...

RT-PCR detects chimeric BCR-ABL mRNA in approximately 25% of adult acute lymphoblastic leukemia (ALL) cases. Minor breakpoint transcripts (e1a2) are found in about 70% of positive cases and major breakpoint transcripts (e13a2, e14a2) in about 30% of cases. However, other atypical transcripts are sometimes observed. We report experience gained in the GMALL Study Group and identified 8 BCR-ABL-po...

Blastic transformation of chronic myelogenous leukemia (CML) is characterized by the presence of nonrandom, secondary genetic abnormalities in the majority of Philadelphia1 clones, and loss of p53 tumor suppressor gene function is a consistent finding in 25-30% of CML blast crisis patients. To test whether the functional loss of p53 plays a direct role in the transition of chronic phase to blas...

A new and rare type of Bcr/Abl junction between exon C3 of the 3' portion of the Bcr gene and Abl exon 2 has been identified in the leukemic cells of two Ph1-positive chronic myelogenous leukemia patients in chronic phase. This is the fourth type of Bcr/Abl junction so far identified in Ph1-positive hematologic malignancies and is a consequence of an unusual breakpoint position on chromosome 22...

We report a case of an asymptomatic 39-year-old male who was incidentally found to have a white blood cell count of 15 000/mm(3) associated with a positive BCR-ABL/t(9;22)(q34;q11) chromosomal translocation detected in 51/300 of cells by FISH and RT-PCR from peripheral blood. Within the next 3 months, leukocytosis spontaneously subsided; however, BCR-ABL by RT-PCR and FISH was persistent both i...

Oncogenic forms of the Abl and Src tyrosine kinases trigger the destruction of the Abi proteins, a family of Abl-interacting proteins that antagonize the oncogenic potential of Abl after overexpression in fibroblasts. The destruction of the Abi proteins requires tyrosine kinase activity and is dependent on the ubiquitin-proteasome pathway. We show that degradation of the Abi proteins occurs thr...

Interferon-alpha (IFN-alpha) induces cytogenetic responses of variable degree in patients with chronic myelogenous leukemia (CML). We sought to establish the relationship between BCR-ABL transcript numbers measured by competitive 2-step reverse transcription polymerase chain reaction (RT-PCR) and cytogenetic status in CML patients treated with IFN-alpha. A total of 250 peripheral blood and 55 b...

Nonreceptor tyrosine kinase Abl is an actin-binding protein and a key regulator of neuronal axonal development. Although Abl family kinases also are localized in dendrites and are implicated in postsynaptic functions, it is not clear how Abl kinases regulate dendritic morphogenesis. Using a developing hippocampal culture as a model, we found that the inhibition of Abl kinases by STI571 leads to...