Molecular and functional characterizations of the association and interactions between nucleophosmin-anaplastic lymphoma Kinase and type I Insulin-like growth factor receptor

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) is aberrantly expressed in a subset of T cell lymphoma that commonly affects children and young adults. NPM-ALK possesses significant oncogenic potential that was previously documented using in vitro and in vivo experimental models. The exact mechanisms by which NPM-ALK induces its effects are poorly understood. We have recently demonstrated that NPM-ALK is physically associated with type I insulin-like growth factor receptor (IGF-IR). A positive feedback loop appears to exist between NPM-ALK and IGF-IR through which these two kinases interact to potentiate their effects.We have also found that a single mutation of the Tyr⁶⁴⁴ or Tyr⁶⁶⁴ residue of the C terminus of NPM-ALK to phenylalanine decreases significantly, but does not completely abolish, the association between NPM-ALK and IGF-IR. The purpose of this study was to determine whether the dual mutation of Tyr⁶⁴⁴ and Tyr⁶⁶⁴ abrogates the association and interactions between NPM-ALK and IGF-IR. We also examined the impact of this dual mutation on the oncogenic potential of NPM-ALK. Our results show that NPMALKY^{644, 664F} completely lacks association with IGF-IR. Importantly, we found that the dual mutation of Tyr⁶⁴⁴ and Tyr⁶⁶⁴ diminishes the oncogenic effects of NPM-ALK, including its ability to induce anchorage-independent colony formation and to sustain cellular transformation, proliferation, and migration. Furthermore, the association between NPM-ALK and IGF-IR through Tyr⁶⁴⁴ and Tyr⁶⁶⁴ appears to contribute to maintaining the stability of NPM-ALK protein. Our results provide novel insights into the mechanisms by which NPM-ALK induces its oncogenic effects through interactions with IGF-IR in this aggressive lymphoma.