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2755 Metformin Upregulates Mir-26a to Improve Erythropoiesis in Preclinical Models of Diamond Blackfan Anemia through Suppression of Nlk Expression

Program: Oral and Poster Abstracts
Session: 508. Bone Marrow Failure: Poster III
Hematology Disease Topics & Pathways:
Anemias, Diseases, Diamond Blackfan Anemia, Bone Marrow Failure, red blood cells, Biological Processes, Cell Lineage, hematopoiesis, signal transduction
Monday, December 7, 2020, 7:00 AM-3:30 PM

Mark C Wilkes, PhD1, Kavitha Siva, PhD2*, Jacqueline D Mercado3, Ethan Patrick Wentworth1*, Mallika Saxena1*, Jun Chen, MD, PhD2*, Anupama Narla, MD1, Bertil Glader, MD, PhD1, Shuo Lin, PhD4*, Manuel Serrano, PhD5*, Johan Flygare, MD, PhD2 and Kathleen M. Sakamoto, MD, PhD1

1Department of Pediatrics, Stanford University School of Medicine, Stanford, CA
2Molecular Medicine and Gene Therapy, Lund Strategic Center for Stem Cell Biology, Lund University, Lund, Sweden
3Michigan State University College of Human Medicine, East Lansing
4Department of Molecular, Cell & Developmental Biology, University of California, Los Angeles, Los Angeles, CA
5Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain

Nemo-like Kinase (NLK) is an atypical member of the Mitogen-activated protein (MAP) kinase family and shares a highly conserved kinase domain with other MAP kinases. For this reason it is challenging to design small molecules that specifically inhibit NLK. In hematopoiesis, NLK expression is suppressed in all lineages except erythroid progenitors. In non-erythroid progenitors, micro-ribonucleic acid (miR)-181 is upregulated and binds to the 3’ untranslated region (UTR) of NLK transcripts, resulting in dramatic degradation of NLK transcripts.

NLK is not activated or required for healthy erythropoiesis, but in Diamond Blackfan Anemia (DBA), NLK is chronically hyper-activated, which contributes to failed erythroid expansion and disease pathogenesis. Given the sensitivity of NLK transcripts to 3’UTR binding-mediated degradation, we hypothesized that targeting NLK degradation by upregulating miRNAs that bind the NLK 3’-UTR could provide an alternative approach to directly inhibiting the kinase to suppress aberrant NLK activity in bone marrow progenitors from DBA patients.

One miRNA binding site that is present in the NLK-3’UTR is miR-26a. We determined that miR-26a is upregulated 2.4-fold (p=0.009) in CD235+ erythrocytes by the Type 2 diabetes drug metformin. Metformin suppressed NLK expression 62.4% (p=0.006) and improved erythroid expansion 4-fold (p=0.001) in human and 6-fold (p=0.042) in zebrafish models of DBA. This effect required an intact miR-26a binding site within the NLK 3’UTR. However, metformin failed to induce miR-26a in murine models of DBA, however the exogenous expression of miR-26a suppressed NLK 36.4% (p=0.028) and improved erythropoiesis 2-fold (p=0.017).

In summary, targeted suppression of NLK through metformin-mediated upregulation of NLK transcript-binding miRNAs effectively improved red blood cell production from 5.6% up to 33.3% of controls in a preclinical model of DBA. These results suggest that metformin is a potential drug for treatment of DBA.

Disclosures: Glader: Agios Pharmaceuticals, Inc.: Consultancy.

OffLabel Disclosure: metformin. This drug is given to differentiating HSPCs in vitro to examine effect on specific kinases.

*signifies non-member of ASH