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Inhibition of Rac controls NPM-ALK-dependent lymphoma development and dissemination.

ABSTRACT: Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) is a tyrosine kinase oncogene responsible for the pathogenesis of the majority of human ALK-positive lymphomas. We recently reported that it activated the Rac1 GTPase in anaplastic large-cell lymphoma (ALCL), leading to Rac-dependent formation of active invadopodia required for invasiveness. Herein, we went further into the study of this pathway and used the inhibitor of Rac, NSC23766, to validate its potential as a molecular target in ALCL in vitro and in vivo in a xenograft model and in a conditional model of NPM-ALK transgenic mice. Our data demonstrate that Rac regulates important effectors of NPM-ALK-induced transformation such as Erk1/2, p38 and Akt. Moreover, inhibition of Rac signaling abrogates NPM-ALK-elicited disease progression and metastasis in mice, highlighting the potential of small GTPases and their regulators as additional therapic targets in lymphomas.

SUBMITTER: Colomba A

PROVIDER: S-EPMC3255265 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Inhibition of Rac controls NPM-ALK-dependent lymphoma development and dissemination.

Colomba A A Giuriato S S Dejean E E Thornber K K Delsol G G Tronchère H H Meggetto F F Payrastre B B Gaits-Iacovoni F F

Blood cancer journal 20110603 6

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) is a tyrosine kinase oncogene responsible for the pathogenesis of the majority of human ALK-positive lymphomas. We recently reported that it activated the Rac1 GTPase in anaplastic large-cell lymphoma (ALCL), leading to Rac-dependent formation of active invadopodia required for invasiveness. Herein, we went further into the study of this pathway and used the inhibitor of Rac, NSC23766, to validate its potential as a molecular target in ALCL in v ...[more]

PMID: 22829165

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Project description:BackgroundNucleophosmin-anaplastic lymphoma kinase-expressing (NPM-ALK+) T cell lymphoma is an aggressive neoplasm. NPM-ALK, an oncogenic tyrosine kinase, plays a critical role in this lymphoma. Recently, selective ALK inhibitors have emerged as a first-line therapy for this neoplasm. Unfortunately, ALK inhibitors were hindered by emergence of resistance and relapse. We have previously demonstrated that type I insulin-like growth factor receptor (IGF-IR) is commonly expressed and activated in this lymphoma. In addition, IGF-IR and NPM-ALK are physically associated and reciprocally enhance their phosphorylation/activation. Herein, we tested the hypothesis that combined inhibition of IGF-IR and NPM-ALK could significantly improve the effects of inhibiting each kinase alone.MethodsWe used clinically utilized inhibitors of IGF-IR (picropodophyllin; PPP) and ALK (ASP3026) to assess the in vitro cellular effects of combined treatment versus treatment using a single agent. Moreover, we used a systemic NPM-ALK+ T cell lymphoma mouse model to analyze the in vivo effects of PPP and ASP3026 alone or in combination.ResultsOur data show that combined treatment with PPP and ASP3026 decreased the viability, proliferation, and anchorage-independent colony formation, and increased apoptosis of NPM-ALK+ T cell lymphoma cells in vitro. The in vitro effects of combined treatment were synergistic and significantly more pronounced than the effects of PPP or ASP3026 alone. Biochemically, simultaneous antagonism of IGF-IR and ALK induced more pronounced decrease in pIGF-IRY1135/1136, pNPM-ALKY646, and pSTAT3Y705 levels than antagonizing IGF-IR or ALK alone. Moreover, combined targeting of IGF-IR and NPM-ALK decreased significantly systemic lymphoma tumor growth and improved mice survival in vivo. Consistent with the in vitro results, the in vivo effects of the combined therapy were more pronounced than the effects of targeting IGF-IR or ALK alone.ConclusionsCombined targeting of IGF-IR and ALK is more effective than targeting IGF-IR or ALK alone in NPM-ALK+ T cell lymphoma. This strategy might also limit emergence of resistance to high doses of ALK inhibitors. Therefore, it could represent a successful therapeutic approach to eradicate this aggressive lymphoma. Importantly, combined inhibition is feasible because of the clinical availability of IGF-IR and ALK inhibitors. Our findings are applicable to other types of cancer where IGF-IR and ALK are simultaneously expressed.

Project description:Nucleophosmin-anaplastic lymphoma kinase-expressing (NPM-ALK+ ) T-cell lymphoma is an aggressive neoplasm that is more commonly seen in children and young adults. The pathogenesis of NPM-ALK+ T-cell lymphoma is not completely understood. Wild-type ALK is a receptor tyrosine kinase that is physiologically expressed in neural tissues during early stages of human development, which suggests that ALK may interact with neurotrophic factors. The aberrant expression of NPM-ALK results from a translocation between the ALK gene on chromosome 2p23 and the NPM gene on chromosome 5q35. The nerve growth factor (NGF) is the first neurotrophic factor attributed to non-neural functions including cancer cell survival, proliferation, and metastasis. These functions are primarily mediated through the tropomyosin receptor kinase A (TrkA). The expression and role of NGF/TrkA in NPM-ALK+ T-cell lymphoma are not known. In this study, we tested the hypothesis that TrkA signaling is upregulated and sustains the survival of this lymphoma. Our data illustrate that TrkA and NGF are expressed in five NPM-ALK+ T-cell lymphoma cell lines and TrkA is expressed in 11 of 13 primary lymphoma tumors from patients. In addition, we found evidence to support that NPM-ALK and TrkA functionally interact. A selective TrkA inhibitor induced apoptosis and decreased cell viability, proliferation, and colony formation of NPM-ALK+ T-cell lymphoma cell lines. These effects were associated with downregulation of cell survival regulatory proteins. Similar results were also observed using specific knockdown of TrkA in NPM-ALK+ T-cell lymphoma cells by siRNA. Importantly, the inhibition of TrkA signaling was associated with antitumor effects in vivo, because tumor xenografts in mice regressed and the mice exhibited improved survival. In conclusion, TrkA plays an important role in the pathogenesis of NPM-ALK+ T-cell lymphoma, and therefore, targeting TrkA signaling may represent a novel approach to eradicate this aggressive neoplasm.

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Inhibition of Rac controls NPM-ALK-dependent lymphoma development and dissemination.

Publications

Inhibition of Rac controls NPM-ALK-dependent lymphoma development and dissemination.

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