Impaired intranuclear trafficking of Runx2 (AML3/CBFA1) transcription factors in breast cancer cells inhibits osteolysis in vivo.
Runx transcription factors comprise a family of proteins that are essential for organogenesis. A unique nuclear matrix-targeting signal in the C terminus directs these factors to their appropriate subnuclear domains. At these sites, they interact with coregulatory proteins and target genes. We have previously shown that aberrant expression of the Runx2 DNA binding domain in metastatic breast cancer cells can prevent production of osteolytic lesions in bone. Here, we show that proper Runx2 subnuclear targeting is required for osteolysis. We have identified point mutations of the Runx2 nuclear matrix-targeting signal sequence that impair its targeting to nuclear matrix sites. These mutations block the invasive and osteolytic properties of MDA-MB-231 breast cancer cells in vivo. Cell lines expressing this Runx2 mutant protein inhibit the osteogenic properties of bone marrow stromal cells in coculture assays. The mutant breast cancer cells also exhibit reduced invasiveness in vitro and do not express genes involved in invasion and angiogenesis (VEGF and MMP13). Our findings suggest that fidelity of Runx2 intranuclear organization is necessary for expression of target genes that mediate the osteolytic activity of metastatic breast cancer cells.
Javed
Amjad
A
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
Barnes
George L
GL
Pratap
Jitesh
J
Antkowiak
Tomasz
T
Gerstenfeld
Louis C
LC
van Wijnen
Andre J
AJ
Stein
Janet L
JL
Lian
Jane B
JB
Stein
Gary S
GS
D021581:Active Transport, Cell Nucleus; D001483:Base Sequence; D001665:Binding Sites; D001859:Bone Neoplasms / Q000235:genetics / Q000556:secondary; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000502:physiology; D017364:Collagenases / Q000235:genetics; D050659:Core Binding Factor Alpha 1 Subunit; D050657:Core Binding Factor alpha Subunits; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D053509:Matrix Metalloproteinase 13; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics; D010014:Osteolysis / Q000517:prevention & control*; D016133:Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism*
D050659:Core Binding Factor Alpha 1 Subunit; D050657:Core Binding Factor alpha Subunits; D017931:DNA Primers; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D014157:Transcription Factors; D017364:Collagenases; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13