November 2011

Document Type


Degree Name



Dept. of Cell and Developmental Biology


Oregon Health & Science University


Aberrant tyrosine kinase activity is commonly implicated in the pathogenesis of leukemia and other cancers. Identification of these leukemogenic tyrosine kinases has proven invaluable for diagnostic and prognostic stratification of patients as well as for the development of novel strategies for therapeutic intervention. The Druker lab has previously demonstrated that siRNA screening of mononuclear cells from leukemia patients can determine sensitivity to loss of individual tyrosine kinases. With the goal of uncovering novel viability-dependent tyrosine kinases in leukemia patients, we have employed an RNAi-assisted protein target identification (RAPID) assay to screen cytogenetic subtypes of acute lymphoblastic leukemia (ALL). ALL is the most common pediatric cancer, accounting for one-quarter of all childhood malignancies. Childhood ALL has a primarily B-cell precursor phenotype and is characterized by chromosomal abnormalities, primarily translocations and duplications. One of the most common recurring translocations associated with pediatric ALL, t(1;19)(q23;p13.3), generates the E2A-PBX1 fusion product. Here I show unique viability-dependent expression of a receptor tyrosine kinase, ROR1, in the t(1;19) ALL background. In addition, I identify a kinase inhibitor, dasatinib, with significant activity against t(1;19) ALL cells due to its capacity to inhibit tyrosine kinases necessary for transduction of pre-B-cell receptor (pre-BCR) signaling. Finally, I show that ROR1 and the pre-BCR activate mutually compensatory signaling pathways, suggesting that optimal therapeutic regimens would include agents targeting both pathways.




School of Medicine



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