Functional characterization of cooperating MGA mutations in RUNX1::RUNX1T1 acute myeloid leukemia.

Area of Science:

• Hematology
• Molecular Biology
• Cancer Biology

Background:

• Max-gene associated (MGA) is a transcription factor that suppresses proliferation and promotes differentiation.
• MGA loss-of-function mutations are found in hematological neoplasms like acute myeloid leukemia (AML).
• The precise impact of MGA alterations on hematopoiesis and AML progression remains unclear.

Purpose of the Study:

• To investigate the functional consequences of MGA mutations in hematopoiesis and AML.
• To elucidate the molecular mechanisms by which MGA loss affects cell proliferation and leukemogenesis.
• To determine the role of MGA in cooperating with the RUNX1::RUNX1T1 fusion oncogene.

Main Methods:

• Analysis of patient-derived MGA mutations for protein-protein interactions and transcriptional activity.
• Utilized human and mouse model systems, including a novel conditional MGA knock-out mouse.
• Assessed gene expression, signaling pathways (MYC, E2F, mTOR), chromatin state, and AML development in MGA-deficient models.

Main Results:

• MGA mutations impair its protein interactions and transcriptional repression of MYC targets.
• Loss of MGA in hematopoietic cells upregulates MYC/E2F targets, cell cycle genes, mTOR signaling, and oxidative phosphorylation, enhancing proliferation.
• MGA deficiency leads to an open chromatin state at proliferation-associated gene promoters.
• RUNX1::RUNX1T1 expression in MGA-deficient cells results in more aggressive AML with faster onset.

Conclusions:

• MGA acts as a crucial regulator of multiple pro-proliferative pathways in hematopoietic cells.
• MGA loss cooperates with the RUNX1::RUNX1T1 fusion oncogene to drive aggressive leukemogenesis.
• MGA is a potential tumor suppressor in hematopoiesis, and its inactivation contributes to AML pathogenesis.