RUNX1 translocations in malignant hemopathies

Area of Science:

• Genetics
• Molecular Biology
• Hematopoiesis

Background:

• The RUNX gene family, including RUNX1, RUNX2, and RUNX3, encodes transcription factors critical for development and cancer.
• RUNX1 is essential for establishing definitive hematopoiesis and generating hematopoietic stem cells.
• RUNX1 function is modulated by interactions with various cofactors, allowing it to act as both an activator and repressor.

Purpose of the Study:

• To review the roles of the RUNX1 gene in development and cancer.
• To elucidate the mechanisms of leukemogenesis associated with RUNX1 alterations, focusing on translocations.
• To detail the molecular characteristics of RUNX1 translocations and their functional consequences.

Main Methods:

• Literature review of studies on RUNX gene family, RUNX1 function, and leukemogenesis.
• Analysis of reported RUNX1 gene alterations, including point mutations, amplifications, and translocations.
• Molecular characterization of RUNX1 fusion transcripts and their impact on protein function.

Main Results:

• RUNX1 alterations, specifically translocations, are recognized modes of leukemogenesis.
• 32 partner chromosomes have been associated with RUNX1 translocations, with partner genes identified in 17 cases.
• Most RUNX1 translocations create fusion transcripts; however, those retaining the Runt homology domain (RHD) but lacking the transactivation domain act as dominant-negative inhibitors of wild-type RUNX1, promoting leukemia.

Conclusions:

• RUNX1 alterations, particularly translocations, are significant contributors to leukemia development.
• The specific nature of RUNX1 fusion proteins, especially the retention of RHD and loss of the transactivation domain, dictates their oncogenic potential.
• Understanding these molecular mechanisms is crucial for comprehending RUNX1-associated leukemogenesis.