Autocrine activation of the MET receptor tyrosine kinase in acute myeloid leukemia

Abstract

Although the treatment of acute myeloid leukemia (AML) has improved significantly, more than half of all patients develop disease that is refractory to intensive chemotherapy1,2. Functional genomics approaches offer a means to discover specific molecules mediating aberrant growth and survival of cancer cells3–8. Thus, using a loss-of-function RNA interference genomic screen, we identified aberrant expression of the hepatocyte growth factor (HGF) as a critical factor in AML pathogenesis. We found HGF expression leading to autocrine activation of its receptor tyrosine kinase, MET, in nearly half of the AML cell lines and clinical samples studied. Genetic depletion of HGF or MET potently inhibited the growth and survival of HGF-expressing AML cells. However, leukemic cells treated with the specific MET kinase inhibitor crizotinib developed resistance due to compensatory upregulation of HGF expression, leading to restoration of MET signaling. In cases of AML where MET is coactivated with other tyrosine kinases, such as fibroblast growth factor receptor 1 (FGFR1)9, concomitant inhibition of FGFR1 and MET blocked compensatory HGF upregulation, resulting in sustained logarithmic cell kill both in vitro and in xenograft models in vivo. Our results demonstrate widespread dependence of AML cells on autocrine activation of MET, as well as the importance of compensatory upregulation of HGF expression in maintaining leukemogenic signaling by this receptor. We anticipate that these findings will lead to the design of additional strategies to block adaptive cellular responses that drive compensatory ligand expression as an essential component of the targeted inhibition of oncogenic receptors in human cancers.

Antibody-based detection of protein phosphorylation status to track the efficacy of novel therapies using nanogram protein quantities from stem cells and cell lines

“…Multiplex signaling data can be acquired from as few as 1x10 4 cells, meaning that multiple subsets of cells can be identified within a heterogeneous population 38 . Up to 15 distinct signaling events can be assayed simultaneously in live cells.…”

“…Different iterations of the technology have subsequently been employed in a range of studies, starting with the Firefly instrument (Protein Simple, formerly Cell Biosciences) in which imatinib induced changes in ERK1 and ERK2 activation status were assessed in human CML cells isolated from total blood, whilst a range of phosphorylation changes in proteins including STAT3 and STAT5 were defined for the K562 CML cell line 2 . Next generation systems (NanoPro 1000, formally CB1000) have been used to study proteins including AKT, 4EBP1, MET, PTPRC/CD45 and CrkL in a number of leukemias, using different primary cell types including murine CD138 + isolated from bone marrow (BM), human CD34-selected acute myeloid leukemia (AML) cells, CML-derived CD34+ and dendric cells [3][4][5][6] .…”

Cell-Autonomous and Non–Cell-Autonomous Mechanisms of HGF/MET–Driven Resistance to Targeted Therapies: From Basic Research to a Clinical Perspective

“…Autocrine MET activation has been described in sarcoma, glioblastoma, breast carcinoma (reviewed in ref. 25 ), and, very recently, in a high percentage of acute myelogenous leukemia ( 26 ). Finally, the unequivocal evidence linking MET and human cancer came from the identifi cation of germline activating mutations in patients suffering from hereditary papillary renal carcinomas ( 27,28 ).…”

Analysis of 1,115 Patients Tested for MET Amplification and Therapy Response in the MD Anderson Phase I Clinic

“…Hepatocyte growth factor (HGF) is the natural ligand of c-MET and its autocrine or paracrine (by tumor surrounding stroma) secretion of HGF may lead to increased c-MET activity in some cancers (3). Additional mechanisms of c-MET activation in cancer are receptor overexpression, gene mutation, and amplification (4).…”