Genetic analyses of Myc and hypusine circuits in tumorigenesis.

Abstract

A prominent metabolic pathway induced by MYC family oncoproteins in cancer is the polyamine-hypusine circuit, which post-translationally modifies a specific lysine residue of eukaryotic translation initiation factor 5 A (eIF5A) with a unique amino acid coined hypusine [N^ε-(4-amino-2-hydroxybutyl)lysine]. This modification occurs in a two-step process, whereby the aminobutyl group of the polyamine spermidine is covalently linked to lysine-50 of eIF5A via deoxyhypusine synthase (DHPS) to form the intermediate deoxyhypusinated eIF5A, which is subsequently hydoxylated by deoxyhypusine hydroxylase (DOHH) to form the fully mature eIF5A^Hyp. As a result, eIF5A^Hyp is elevated in MYC-driven cancers. Recently it has become evident that eIF5A^Hyp (i) plays key roles in the development, progression and maintenance of tumors; and (ii) eIF5A^Hyp functions are often tissue/cell context-specific. Thus, it is important to mechanistically assess how eIF5A^Hyp affects normal cells and tumorigenesis using suitable in vivo and ex vivo models. In this chapter, we describe the methods used in our laboratory to assess the effects of MYC-polyamine-hypusine axis on the development and maintenance of MYC-driven B-cell lymphoma. The goals of this chapter are twofold. First, we discuss genetic and cell biological approaches that can be applied to assess roles of eIF5A^Hyp on lymphoma and normal B cell development. Second, we discuss methods that can be used to assess the roles of eIF5A^Hyp on the growth and maintenance of lymphoma. Collectively, these approaches provide a template that can be applied to evaluate roles of any putative regulator of the development and/or maintenance of lymphoma.