AG Buske

Fusion genes or mutations are molecular hallmarks of acute leukemias. Examples are the AML1-ETO fusion gene or the NPM1 mutation which are among the most frequent genetic alterations found in patients with AML. The research program focuses on dissecting the oncogenic mechanisms of these genetic alterations using bone marrow transplantation models or knock-out models. As experimental models have shown that these alterations on its own are insufficient to induce leukemic transformation, we are using these models to identify collaborating genetic alterations which are recurrently found in patients with AML and the mentioned genotypes.

Another focus of the laboratory deals with the analyses of non-coding RNAs in the pathobiology of acute leukemias. At the moment we focus on a microRNA (miR-196) which is embedded in the homeobox gene cluster and is highly expressed in patients with AML. We have established mouse models which mimick the aberrant expression of mir-196 in normal hematopoietic progenitor/stem cells and are analysing its effect on already established murine leukemias. Another focus is the class of piRNAs, which have important roles together with so called Piwi proteins to control transposon activity in germ line stem cells. So far there role in leukemic stem cells is not known.

Domains of Piwi genes                                 Structure of Piwi-interacting RNAs (pi-RNA)

Acute myeloid leukemia is initiated and maintained by a so called leukemic stem cell (LSCs). We are interested in delineating cellular and molecular differences between normal hematopoietic stem cells and leukemic stem cells with the goal to identify LSC characteristics which are druggable. We have previously shown that LSCs can carry lymphoid characteristics, which discriminates them from normal hematopoietic stem cells. This could be a basis for developing therapies which target LSCs but spare normal hematopoietic stem cells.

To identify novel vulnerability genes at the level of LSCs we will use RNAi library screens in appropriate mouse models, in which we can highly purify LSCs and separate them from normal hematopoietic stem cells.

Deshpande et al., Cancer Cell 2006

Homeobox genes are highly conserved transcription factors which play a major role in embryogenesis, but also key players in normal hematopoietic development. Importantly, it has been shown that aberrant expression of homeobox genes is one of the molecular hallmarks of acute myeloid leukemia and that aberrant expression of a subgroup of homeobox genes is leukemogenic in murine experimental models. One focus in this respect is the highly leukemogenic homeobox gene Cdx2 and the class of TALE homeobox genes such as Meis1. In parallel, we are investigating homeobox genes such as HoxB4, which itself is not leukemogenic but is known to amplify normal hematopoietic stem cells. By structure – function analyses we try to identify gene domains which are responsible for the oncogenic or stem cell amplificatory properties of homeobox genes.