Genomic Promoter Occupancy of Runt-related Transcription Factor RUNX2 in Osteosarcoma Cells Identifies Genes Involved in Cell Adhesion and Motility

Abstract

Background:The osteogenic Runt-related (RUNX) transcription factor Runx2 is frequently elevated in osseous and nonosseous tumor cells. Results: Genomic RUNX2 target genes involved in motility were identified; RUNX2 depletion reduces cell motility in osteosarcoma cells. Conclusion: RUNX2 regulates cell motility and adhesion in osteosarcoma cells. Significance: RUNX2 may also control migration of normal osteoblasts and/or tumor cells.

The RUNX2 Cistrome in Osteoblasts

“…As RUNX2 sites located distal to gene promoters represent the norm rather than the exception, as illuminated unequivocally in the present study, the general lack of correlation between RUNX2 binding and target gene regulation evident in this earlier study is likely due to the lack of detection of distal RUNX2 sites. Interestingly, siRNA mediated down-regulation of RUNX2 was not entirely effective in depleting RUNX2 binding at many target genes (32), suggesting that this approach could be problematic. Approximately 1,603 RUNX2 binding sites were noted across the prostate cell line genome upon induction of RUNX2 (33).…”

“…Our study of the RUNX2 cistrome in osteoblasts appears unique as similar analyses have not yet been reported. Two recent studies of RUNX2 binding activity have been conducted, however, the first reported a ChIP-seq analysis of the RUNX2 cistrome in a RUNX2-null prostate cell line engineered to express RUNX2 in a doxycycline-sensitive manner (33) and the second reported a ChIP-chip analysis of RUNX2 binding at a genome-wide collection of gene promoter regions in the osteosarcoma cell line MG63 (32). The latter identified a collection of 2,265 RUNX2 binding sites that were correlated with adjacent genes, several of which were investigated further as contributing to cancer cell migration and adhesion.…”

“…A clear understanding of the network of genes that are directly regulated by RUNX2 has not been delineated however, due primarily to this factor's diverse biological role in osteoblast lineage cells as well as its complex regulation. A recent ChIP-chip analysis which coupled the binding of RUNX2 at a genome-wide collection of promoter regions in osteosarcoma cells to gene expression has defined a number of potential genetic sites of action of RUNX2 (32). In addition, an unbiased genome-wide ChIP-seq analysis using RUNX2-negative prostate cells engineered to express RUNX2 in a doxycycline-conditional manner suggests a limited RUNX2 cistrome that is enriched for the cognate RUNX2 binding site motif (33).…”

MicroRNA-34c Inversely Couples the Biological Functions of the Runt-related Transcription Factor RUNX2 and the Tumor Suppressor p53 in Osteosarcoma

“…Furthermore, genomewide chromatin immune-precipitation experiments using microarrays ("ChIP-on-chip" analysis) for RUNX2 in SAOS-2 cells revealed that RUNX2 controls genes involved in cell motility and adhesion (38). Thus, the loss of p53 that frequently accompanies OS formation may elevate the levels of RUNX2 and increase the metastatic potential of OS.…”

Molecular characterization of metastatic osteosarcoma: Differentially expressed genes, transcription factors and microRNAs

“…Transcription factors (TFs) (9) and microRNAs (miRNAs) (10) are the two critical regulators targeting protein-coding genes involved in cancer initiation and progression. For example, runt-related transcription factor 2 may support the cell adhesion and motility of osteosarcoma cells (11). In addition, it has previously been reported that overexpression of SRY (sex determining region Y)-box 9, Wnt family member 1 and frizzled class receptor 1 may be associated with an advanced clinical stage (12), whereas inhibition of Wnt may markedly reduce the lung metastasis of osteosarcoma (13).…”