Heidi Erickson

RNAi screen for rapid therapeutic target identification in leukemia patients

Targeted therapy has vastly improved outcomes in certain types of cancer. Extension of this paradigm across a broad spectrum of malignancies will require an efficient method to determine the molecular vulnerabilities of cancerous cells. Improvements in sequencing technology will soon enable high-throughput sequencing of entire genomes of cancer patients; however, determining the relevance of identified sequence variants will require complementary functional analyses. Here, we report an RNAi-assisted protein target identification (RAPID) technology that individually assesses targeting of each member of the tyrosine kinase gene family. We demonstrate that RAPID screening of primary leukemia cells from 30 patients identifies targets that are critical to survival of the malignant cells from 10 of these individuals. We identify known, activating mutations in JAK2 and K-RAS, as well as patient-specific sensitivity to down-regulation of FLT1, CSF1R, PDGFR, ROR1, EPHA4/5, JAK1/3, LMTK3, LYN, FYN, PTK2B, and N-RAS. We also describe a previously undescribed, somatic, activating mutation in the thrombopoietin receptor that is sensitive to down-stream pharmacologic inhibition. Hence, the RAPID technique can quickly identify molecular vulnerabilities in malignant cells. Combination of this technique with whole-genome sequencing will represent an ideal tool for oncogenic target identification such that specific therapies can be matched with individual patients.

High-throughput mutational screen of the tyrosine kinome in chronic myelomonocytic leukemia

High-throughput mutational screen of the tyrosine kinome in chronic myelomonocytic leukemia

Functional characterization of an activating TEK mutation in acute myeloid leukemia: a cellular context-dependent activating mutation

Therapies that are targeted to the molecular genetic defect of malignancies have proven more successful than conventional chemotherapeutic approaches.1, 2, 3, 4 A broad application of this strategy will require a detailed understanding of the genetic lesions involved in oncogenesis. Tyrosine kinases constitute a gene family of 91 members that play a critical role in numerous cellular processes, and aberrant regulation of tyrosine kinase activity has been observed in numerous types of malignancies.5 One malignancy in which tyrosine kinases are abnormally regulated is acute myeloid leukemia (AML). Several reports have shown that signal transducer and activator of transcription 5 (STAT5) is phosphorylated in blast cells from at least 70% of patients with AML.6, 7, 8 STAT5 phosphorylation is tightly controlled by tyrosine kinase signaling networks; hence this suggests the presence of aberrantly active, mutated tyrosine kinases in these patients.