Role of IGF-IR tyrosine kinase in NPM-ALK-expressing T-cell lymphoma

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DESCRIPTION (provided by applicant): Nucleophosmin-anaplastic lymphoma kinase-expressing anaplastic large-cell lymphoma (NPM-ALK+ ALCL) is an aggressive type of T-cell lymphoma. Although it occurs in patients of all ages, NPM-ALK+ ALCL is more frequently seen in young patients, accounting for 20-30% of non-Hodgkin's lymphomas in children and young adults. Patients typically present with advanced-stage disease and generalized involvement of the lymph nodes and other organs including skin, bone marrow, and liver. Currently, there is no effective treatment for this lymphoma, and as in other types of T-cell lymphoma, the treatment of NPM-ALK+ ALCL is primarily based on the CHOP combination chemotherapy regimen. After an initial favorable response to CHOP, up to 40% of NPM-ALK+ ALCL patients eventually have a relapse, develop resistance, and, in many cases, die. At the molecular level, NPM-ALK+ ALCL is characterized by the expression of the chimeric tyrosine kinase NPM-ALK, which induces significant oncogenic effects through interactions with downstream molecules that promote lymphoma cell survival. NPM-ALK is structurally similar to the type I insulin-like growth factor receptor (IGF-IR) tyrosine kinase. IGF-IR plays important roles in promoting the survival of several solid tumors such as breast, prostate, lung, and ovarian cancers. Notably, several of the oncogenic molecules downstream of NPM-ALK also function downstream of IGF-IR. Nevertheless, whether IGF-IR has a functional role in NPM-ALK+ ALCL has not been examined. In preliminary studies we found that the expression of IGF-IR is upregulated in NPM-ALK+ ALCL cell lines compared with normal human T-cells. We also found that IGF-IR and NPM-ALK are physically associated and appear to interact through a reciprocal positive feedback loop to maintain their phosphorylation/ activation. An experimental inhibitor of IGF-IR induced apoptosis and cell cycle arrest and abrogated colony formation in soft agar of NPM-ALK+ ALCL cell lines. On the basis of these preliminary results, we hypothesize that upregulation of IGF-IR and its collaboration with NPM-ALK contribute to the survival of NPM-ALK+ ALCL and, therefore, targeting IGF-IR may be a reasonable strategy for treating this lymphoma. The specific aims of this proposal are as follows: 1. To identify the mechanisms by which IGF-IR expression is upregulated in NPM-ALK+ ALCL. 2. To characterize the interactions between IGF-IR and NPM-ALK in vitro and in vivo. 3. To examine the in vitro and in vivo preclinical effects of IGF-IR inhibitors currently being used in clinical trials in NPM-ALK+ ALCL. Our results will provide insight into the role of IGF-IR in NPM-ALK+ ALCL. Our long-term goal is to understand IGF-IR-dependent signaling in this aggressive lymphoma in order to devise novel therapeutic strategies. Tactics that antagonize IGF-IR could potentially provide a cure for NPM-ALK+ ALCL patients. PUBLIC HEALTH RELEVANCE: NPM-ALK+ anaplastic large-cell lymphoma (ALCL) is an aggressive type of T-cell lymphoma that commonly affects children and young adults. After initial response to current therapeutics, 30-40% of patients develop a relapse, and death is not uncommon. In this application, we propose to study the role of the type I insulin-like growth factor receptor (IGF-IR) tyrosine kinase in NPM-ALK+ ALCL, and our long-term goal is to understand IGF-IR-dependent signaling in this lymphoma in order to devise effective treatment strategies.