The Runx genes as dominant oncogenes.

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Runx2 is a frequent target of proviral insertion in murine leukemia virus-induced T cell tumors.
• Insertions in Runx3 or Runx1 were also observed in a subset of these tumors.
• Proviral insertion in each case led to high expression from the upstream (P1) promoter.

Purpose of the Study:

• To investigate the role of Runx genes as oncogenes in T-cell lymphoma.
• To explore the oncogenic potential of Runx2 through overexpression in transgenic mice.
• To understand the synergistic interaction between Runx2 and c-MYC in T-cell lymphoma development.

Main Methods:

• Analysis of a large panel of murine leukemia virus-induced T cell tumors.
• Creation of transgenic mice overexpressing Runx2 in the T cell compartment (CD2-Runx2).
• Co-expression of c-MYC in CD2-Runx2 mice.
• Assessment of Runx1 oncogenic potential in primary murine embryonic fibroblasts (MEFs).

Main Results:

• Runx1, Runx2, and Runx3 appear to function as redundant oncogenes in T-cell lymphoma.
• CD2-Runx2 transgenic mice exhibited preneoplastic enlargement of the CD8 immature single positive (ISP) thymocyte pool and low-incidence lymphomas.
• Co-expression of c-MYC with Runx2 led to rapid tumor development, indicating potent synergy.
• Runx1 showed a growth-promoting effect in p53-deficient MEFs, suggesting latent oncogenic properties.

Conclusions:

• The Runx gene family members (Runx1, Runx2, Runx3) function as redundant oncogenes in T-cell lymphoma.
• Runx2 overexpression can promote T-cell lymphoma development, particularly in synergy with c-MYC.
• Runx genes may possess latent oncogene-like properties, with Runx1 exhibiting growth promotion in the absence of p53.