GATA2 Zinc Finger Mutations Influence Erythroid Differentiation and Chemotherapy Response

The transcription factor GATA2 plays an important role in cell lineage decisions during hematopoiesis. GATA2 Zinc-Finger (ZF) mutations are associated with distinct entities of myeloid malignancies. Alterations of the N-terminal ZF1 were identified in AML patients with biallelic CEBPA mutations, whereas the C-terminal ZF2 is typically affected by germline mutations predisposing to MDS and AML, or by somatic lesions in CML blast crisis. Nevertheless, the context-dependent mechanisms underlying GATA2 ZF mutations remain mostly unclear. Here, we set out to study the functional consequences of GATA2 ZF mutations.

To test the effect on differentiation, we expressed GATA2 wild-type (WT) or GATA2 ZF mutants in human CD34+ hematopoietic stem and progenitor cells, stimulated with appropriate cytokines. Differentiation was evaluated by FACS-measurements of surface marker expression (erythroid markers: CD71, CD235a; granulocytic/monocytic markers: CD15, CD14). GATA2 WT caused a block of erythroid differentiation that is overcome by the ZF1 mutants (A318T and G320D), whereas the ZF2 mutant L359V may aggravate this block. For granulocytic/monocytic differentiation an overall block was observed for GATA2 WT and all the ZF mutants tested (Figure 1 A, B).

Recently, we and others observed GATA2 mutation gain in AML relapse (Greif et al., 2018 Clin Cancer Res; Christopher et al., 2018, NEJM), pointing towards a potential role in therapy resistance. Therefore, we treated K562 cells stably expressing GATA2 WT or mutants with Daunorubicin (one of the two drugs commonly used in AML chemotherapy). Expression of GATA2 A318T in K562 cells correlated with higher sensitivity to Daunorubicin and lower expression levels of IDH2. (Figure 1 C, D). Interestingly, this particular ZF1 mutation was the only one that got lost at relapse in the study by Christopher and colleagues, consistent with therapy sensitivity, whereas most of the GATA2 mutations gained at relapse were localized in the ZF2 domain.

In summary, GATA2 ZF mutations influence hematopoietic differentiation and chemotherapy response in a position-dependent manner. In the present study, we report distinct roles for individual GATA2 mutations depending on the affected ZF domain and altered amino acid positions. Understanding the oncogenic collaboration of GATA2 mutations with other driver genes in distinct patient subgroups is a challenge ahead.

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