Erlotinib exhibits antineoplastic off-target effects in AML and MDS: a preclinical study

Abstract

Erlotinib, an inhibitor of the epidermal growth factor receptor (EGFR), induces differentiation, cell-cycle arrest, and apoptosis of EGFR-negative myeloblasts of patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), as well as in EGFR-negative cell lines representing these diseases (P39, KG-1, and HL 60). This off-target effect can be explained by inhibitory effects on JAK2. Apoptosis induction coupled to mitochondrial membrane permeabilization occurred independently from phenotypic differentiation. In apoptosis-sensitive AML cells, erlotinib caused a rapid (within less than 1 hour) nucleocytoplasmic translocation of nucleophosmin-1 (NPM-1) and p14 ARF . Apoptosis-insensitive myeloblasts failed to manifest this translocation yet became sensitive to apoptosis induction by erlotinib when NPM-1 was depleted by RNA interference. Moreover, erlotinib reduced the growth of xenografted human AML cells in vivo. Erlotinib also killed CD34 ؉ bone marrow blasts from MDS and AML patients while sparing normal CD34 ؉ progenitors. This ex vivo therapeutic effect was once more associated with the nucleocytoplasmic translocation of NPM-1 and p14 ARF . One patient afflicted with both MDS and non-small cell lung cancer manifested hematologic improvement in response to erlotinib. In summary, we here provide novel evidence in vitro, ex vivo, and in vivo for the potential therapeutic efficacy of erlotinib in the treatment of high-risk MDS and AML.

Role of the c subunit of the FOATP synthase in mitochondrial permeability transition

“…Immunoblotting was performed as previously described, with minor modifications. 73 In brief, to obtain whole-cell extracts, cells were washed, harvested and lysed in RIPA buffer (50 mM TRIS-HCl pH 7.8, 150 mM NaCl, 1% IGEPAL CA-630, 0.5% sodium deoxycholate, 0.1% SDS, 1 mM dithiothreitol) supplemented with 2 mM Na 3 VO 4 , 2 mM NaF, 1 mM phenylmethylsulfonyl fluoride and Complete Protease Inhibitor Cocktail ® (Roche Diagnostics Corp.). Alternatively, cytosolic extracts were obtained by digitonin permeabilization, as previously described.…”

Dasatinib promotes ATRA-induced differentiation of AML cells

“…[9][10][11] Impressively, treatment of NSCLC patients harboring concomitant AML with the EGFR inhibitor erlotinib has been shown to result in complete remission of the AML. 12,13 The effects of gefitinib and erlotinib on AML seem to be due to off-target effects on other tyrosine kinases, possibly SFKs, because AML cells do not express EGF receptors.…”

Genomic approaches to small molecule discovery

“…Erlotinib (Tarceva), another FDA-approved EGFR inhibitor, also induced similar effects on cell viability and differentiation in AML. 45,46 Furthermore, gefitinib, in combination with either ATRA or cytotoxic agents, had enhanced activity on differentiation and viability, respectively. 47,48 In HL-60 cells and Kasumi-1 cells, there is no expression of EGFR as determined by negative RT-PCR and western blot analysis, suggesting that the differentiation-promoting activity of gefitinib is through a non-EGFR mechanism of action.…”

“…Interestingly, recent reports describe patients with AML responsive to erlotinib, a structurally related EGFR inhibitor, including two complete remissions. 45,49,50 …”