Runx2 deficiency and defective subnuclear targeting bypass senescence to promote immortalization and tumorigenic potential

Student Author(s)

Sandhya Pande

Academic Program

Cell Biology

UMMS Affiliation

Department of Cell Biology

Publication Date


Document Type



Cancer Biology | Cell Biology | Life Sciences | Medicine and Health Sciences


The osteogenic Runt-related (Runx2) transcription factor negatively regulates proliferation and ribosomal gene expression in normal diploid osteoblasts, but is up-regulated in metastatic breast and prostate cancer cells. Thus, Runx2 may function as a tumor suppressor or an oncogene depending on the cellular context. Here we show that Runx2-deficient primary osteoblasts fail to undergo senescence as indicated by the absence of beta-gal activity and p16(INK4a) tumor suppressor expression. Primary Runx2-null osteoblasts have a growth advantage and exhibit loss of p21(WAF1/CIP1) and p19(ARF) expression. Reintroduction of WT Runx2, but not a subnuclear targeting-defective mutant, induces both p21(WAF/CIP1) and p19(ARF) mRNA and protein resulting in cell-cycle inhibition. Accumulation of spontaneous phospho-H2A.X foci, loss of telomere integrity and the Mre11/Rad50/Nbs1 DNA repair complex, and a delayed DNA repair response all indicate that Runx2 deficiency leads to genomic instability. We propose that Runx2 functions as a tumor suppressor in primary diploid osteoblasts and that subnuclear targeting contributes to Runx2-mediated tumor suppression.

DOI of Published Version



Proc Natl Acad Sci U S A. 2007 Dec 11;104(50):19861-6. Epub 2007 Dec 5. Link to article on publisher's site

Journal/Book/Conference Title

Proceedings of the National Academy of Sciences of the United States of America

Related Resources

Link to Article in PubMed

PubMed ID