Project description:Background: Prostate cancer (PCa) cells preferentially metastasize to bone at least in part by acquiring osteomimetic properties. Runx2, an osteoblast master transcription factor, is aberrantly expressed in PCa cells, and promotes their metastatic phenotype. The transcriptional programs regulated by Runx2 have been extensively studied during osteoblastogenesis, where it activates or represses target genes in a context-dependent manner. However, little is known about the gene regulatory networks influenced by Runx2 in PCa cells. We therefore investigated genome-wide mRNA expression changes in PCa cells in response to Runx2. Results: We engineered a C4-2B PCa sub-line called C4-2B/Rx2dox, in which doxycycline (Dox) treatment stimulates Runx2 expression from very low levels to levels observed in other PCa cells. Transcriptome profiling using whole genome expression array followed by in silico analysis indicated that Runx2 upregulated a multitude of genes with prominent cancer-associated functions. They included secreted factors (CSF2, SDF-1), proteolytic enzymes (MMP9, CST7), cytoskeleton modulators (SDC2, Twinfilin, SH3PXD2A), intracellular signaling molecules (DUSP1, SPHK1, RASD1) and transcription factors (Sox9, SNAI2, SMAD3) functioning in epithelium to mesenchyme transition (EMT), tissue invasion, as well as homing and attachment to bone. Consistent with the gene expression data, induction of Runx2 in C4-2B cells enhanced their invasiveness. It also promoted cellular quiescence by blocking the G1/S phase transition during cell cycle progression. Furthermore, the cell cycle block was reversed as Runx2 levels declined after Dox withdrawal. Conclusions: The effects of Runx2 in C4-2B/Rx2dox cells, as well as similar observations made by employing LNCaP, 22RV1 and PC3 cells, highlight multiple mechanisms by which Runx2 promotes the metastatic phenotype of PCa cells, including tissue invasion, homing to bone and induction of high bone turnover. Runx2 is therefore an attractive target for the development of novel diagnostic, prognostic and therapeutic approaches to PCa management. Targeting Runx2 may prove more effective than focusing on its individual downstream genes and pathways. C4-2B/Rx2dox cells were subjected to microarray gene expression analysis after one and two days of treatment with either Dox or vehicle in biological quadruplicates (a total of 16 samples).

Project description:Background: Prostate cancer (PCa) cells preferentially metastasize to bone at least in part by acquiring osteomimetic properties. Runx2, an osteoblast master transcription factor, is aberrantly expressed in PCa cells, and promotes their metastatic phenotype. The transcriptional programs regulated by Runx2 have been extensively studied during osteoblastogenesis, where it activates or represses target genes in a context-dependent manner. However, little is known about the gene regulatory networks influenced by Runx2 in PCa cells. We therefore investigated genome-wide mRNA expression changes in PCa cells in response to Runx2. Results: We engineered a C4-2B PCa sub-line called C4-2B/Rx2dox, in which doxycycline (Dox) treatment stimulates Runx2 expression from very low levels to levels observed in other PCa cells. Transcriptome profiling using whole genome expression array followed by in silico analysis indicated that Runx2 upregulated a multitude of genes with prominent cancer-associated functions. They included secreted factors (CSF2, SDF-1), proteolytic enzymes (MMP9, CST7), cytoskeleton modulators (SDC2, Twinfilin, SH3PXD2A), intracellular signaling molecules (DUSP1, SPHK1, RASD1) and transcription factors (Sox9, SNAI2, SMAD3) functioning in epithelium to mesenchyme transition (EMT), tissue invasion, as well as homing and attachment to bone. Consistent with the gene expression data, induction of Runx2 in C4-2B cells enhanced their invasiveness. It also promoted cellular quiescence by blocking the G1/S phase transition during cell cycle progression. Furthermore, the cell cycle block was reversed as Runx2 levels declined after Dox withdrawal. Conclusions: The effects of Runx2 in C4-2B/Rx2dox cells, as well as similar observations made by employing LNCaP, 22RV1 and PC3 cells, highlight multiple mechanisms by which Runx2 promotes the metastatic phenotype of PCa cells, including tissue invasion, homing to bone and induction of high bone turnover. Runx2 is therefore an attractive target for the development of novel diagnostic, prognostic and therapeutic approaches to PCa management. Targeting Runx2 may prove more effective than focusing on its individual downstream genes and pathways.

Project description:Runx2 and Axin2 regulate skeletal development. We recently determined that Axin2 and Runx2 molecularly interact in differentiating osteoblasts to regulate intramembranous bone formation, but the relationship between these factors in endochondral bone formation was unresolved. To address this, we examined the effects of Axin2 deficiency on the cleidocranial dysplasia (CCD) phenotype of Runx2+/- mice, focusing on skeletal defects attributed to improper endochondral bone formation. Axin2 deficiency unexpectedly exacerbated calvarial components of the CCD phenotype in the Runx2+/- mice; the endocranial layer of the frontal suture, which develops by endochondral bone formation, failed to mineralize in the Axin2-/-:Runx2+/-mice, resulting in a cartilaginous, fibrotic and larger fontanel than observed in Runx2+/- mice. Transcripts associated with cartilage development (e.g., Acan, miR140) were expressed at higher levels, whereas blood vessel morphogenesis transcripts (e.g., Slit2) were suppressed in Axin2-/-:Runx2+/-calvaria. Cartilage maturation was impaired, as primary chondrocytes from double mutant mice demonstrated delayed differentiation and produced less calcified matrix in vitro. The genetic dominance of Runx2 was also reflected during endochondral fracture repair, as both Runx2+/- and double mutant Axin2-/-:Runx2+/- mice had enlarged fracture calluses at early stages of healing. However, by the end stages of fracture healing, double mutant animals diverged from the Runx2+/- mice, showing smaller calluses and increased torsional strength indicative of more rapid end stage bone formation as seen in the Axin2-/- mice. Taken together, our data demonstrate a dominant role for Runx2 in chondrocyte maturation, but implicate Axin2 as an important modulator of the terminal stages of endochondral bone formation. 4 mice per genotype X 4 genotypes: wildtype (WT), Runx2+/- (R-Het), Axin2-/- (A-KO), Axin2-/-:Runx2+/- (A-KO:R-Het). Total = 16 samples

Dataset Information

Opposing effects of estrogen and Runx2 on breast cancer cell proliferation: identification of a reciprocally-regulated gene signature with clinical prognostic value.

Publications

Opposing effects of Runx2 and estradiol on breast cancer cell proliferation: in vitro identification of reciprocally regulated gene signature related to clinical letrozole responsiveness.

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