The Role of Runx2 in Microtubule Acetylation in Bone Metastatic Breast Cancer Cells.

Bone metastasis of breast cancer results in severe bone loss, fractures, and death. Crosstalk between breast cancer cells and bone resident cells promotes osteoclast activity and the release of growth factors from the bone matrix resulting in aggressive tumor growth and bone loss. We and others have shown that Runt-related transcription factor-2 (Runx2) promotes metastatic tumor growth-associated bone loss.

Bone Metastatic Breast Cancer: Advances in Cell Signaling and Autophagy Related Mechanisms.

Bone metastasis is a frequent complication of breast cancer with nearly 70% of metastatic breast cancer patients developing bone metastasis during the course of their disease. The bone represents a dynamic microenvironment which provides a fertile soil for disseminated tumor cells, however, the mechanisms which regulate the interactions between a metastatic tumor and the bone microenvironment remain poorly understood. Recent studies indicate that during the metastatic process a bidirectional relationship between metastatic tumor cells and the bone microenvironment begins to develop.

Bone metastatic breast cancer cells display downregulation of PKC-ζ with enhanced glutamine metabolism.

Background: Breast cancer is the most commonly diagnosed cancer among women and its metastases results in poor survival rates in patients. The ability to alter metabolism is a key attribute cancer cells use to survive within different metastatic microenvironments and cause organ failure. We hypothesized that evaluation of metabolic alterations within tumor cells could provide a better understanding of cancer metastasis.

The role of Runx2 in facilitating autophagy in metastatic breast cancer cells.

Breast cancer metastases cause significant patient mortality. During metastases, cancer cells use autophagy, a catabolic process to recycle nutrients via lysosomal degradation, to overcome nutritional stress for their survival. The Runt-related transcription factor, Runx2, promotes cell survival under metabolic stress, and regulates breast cancer progression and bone metastases.

The SWI/SNF ATPases Are Required for Triple Negative Breast Cancer Cell Proliferation.

The Brahma (BRM) and Brahma-related Gene 1 (BRG1) ATPases are highly conserved homologs that catalyze the chromatin remodeling functions of the multi-subunit human SWI/SNF chromatin remodeling enzymes in a mutually exclusive manner. SWI/SNF enzyme subunits are mutated or missing in many cancer types, but are overexpressed without apparent mutation in other cancers. Here, we report that both BRG1 and BRM are overexpressed in most primary breast cancers independent of the tumor's receptor status.

Role of Runx2 in crosstalk between Mek/Erk and PI3K/Akt signaling in MCF-10A cells.

Crosstalk among mitogen-activated protein kinase (MAPK) and phosphatidyl inositol 3' kinase (PI3K) signaling pathways integrates extracellular cues to regulate mammary epithelial cell growth, proliferation, differentiation, and survival. The runt-related transcription factor, Runx2, is expressed in normal mammary epithelium and promotes differentiation, however, its function in regulation of the MAPK and PI3K signaling crosstalk is not known. We determined the function of Runx2 expression in growth factor-mediated phosphorylation of Erk1/2 and Akt, key downstream kinases in MAPK and PI3K pathway crosstalk in MCF-10A mammary epithelial cells.

hsa-mir-30c promotes the invasive phenotype of metastatic breast cancer cells by targeting NOV/CCN3.

Background: For treatment and prevention of metastatic disease, one of the premier challenges is the identification of pathways and proteins to target for clinical intervention. Micro RNAs (miRNAs) are short, non-coding RNAs, which regulate cellular activities by either mRNA degradation or translational inhibition. Our studies focused on the invasive properties of hsa-mir30c based on its high expression in MDA-MB-231 metastatic cells and our bioinformatic analysis of the Cancer Genome Atlas that identified aberrant hsa-mir-30c to be associated with poor survival.

Runx2 activates PI3K/Akt signaling via mTORC2 regulation in invasive breast cancer cells.

Introduction: The Runt-related transcription factor Runx2 is critical for skeletal development but is also aberrantly expressed in breast cancers, and promotes cell growth and invasion. A de-regulated serine/threonine kinase Akt signaling pathway is implicated in mammary carcinogenesis and cell survival; however, the mechanisms underlying Runx2 role in survival of invasive breast cancer cells are still unclear.

Methods: The phenotypic analysis of Runx2 function in cell survival was performed by gene silencing and flow cytometric analysis in highly invasive MDA-MB-231 and SUM-159-PT mammary epithelial cell lines.

Integrin αvβ6 promotes an osteolytic program in cancer cells by upregulating MMP2.

The molecular circuitries controlling osseous prostate metastasis are known to depend on the activity of multiple pathways, including integrin signaling. Here, we demonstrate that the αvβ6 integrin is upregulated in human prostate cancer bone metastasis. In prostate cancer cells, this integrin is a functionally active receptor for fibronectin and latency-associated peptide-TGF-β1; it mediates attachment and migration upon ligand binding and is localized in focal contacts.

Runx2 mediates epigenetic silencing of the bone morphogenetic protein-3B (BMP-3B/GDF10) in lung cancer cells.

Background: The Runt-related transcription factor Runx2 is essential for bone development but is also implicated in progression of several cancers of breast, prostate and bone, where it activates cancer-related genes and promotes invasive properties. The transforming growth factor β (TGF-β) family member bone morphogenetic protein-3B (BMP-3B/GDF10) is regarded as a tumor growth inhibitor and a gene silenced in lung cancers; however the regulatory mechanisms leading to its silencing have not been identified.

Results: Here we show that Runx2 is highly expressed in lung cancer cells and downregulates BMP-3B.

Activation of the ERK1/2 mitogen-activated protein kinase cascade by dentin matrix protein 1 promotes osteoblast differentiation.

DMP1 has been shown to play many roles in osteogenesis. We recently demonstrated that calcium-mediated stress kinase activation by DMP1 leads to osteoblast differentiation. In this study we demonstrate that DMP1 can also activate the extracellular signal-regulated kinase (ERK)-MAPK pathway.

The histone deacetylase inhibitor, vorinostat, reduces tumor growth at the metastatic bone site and associated osteolysis, but promotes normal bone loss.

Vorinostat, an oral histone deacetylase inhibitor with antitumor activity, is in clinical trials for hematologic and solid tumors that metastasize and compromise bone structure. Consequently, there is a requirement to establish the effects of vorinostat on tumor growth within bone. Breast (MDA-231) and prostate (PC3) cancer cells were injected into tibias of SCID/NCr mice and the effects of vorinostat on tumor growth and osteolytic disease were assessed by radiography, micro-computed tomography, and histologic and molecular analyses.

Metastatic bone disease: role of transcription factors and future targets.

Progression of cancer from the earliest event of cell transformation through stages of tumor growth and metastasis at a distal site involves many complex biological processes. Underlying the numerous responses of cancer cells to the tumor microenvironment which support their survival, migration and metastasis are transcription factors that regulate the expression of genes reflecting properties of the tumor cell. A number of transcription factors have been identified that play key roles in promoting oncogenesis, tumor growth, metastasis and tissue destruction.

The human SWI/SNF complex associates with RUNX1 to control transcription of hematopoietic target genes.

The acute myeloid leukemia 1 (AML1, RUNX1) transcription factor is a key regulator of hematopoietic differentiation that forms multi-protein complexes with co-regulatory proteins. These complexes are assembled at target gene promoters in nuclear microenvironments to mediate phenotypic gene expression and chromatin-related epigenetic modifications. Here, immunofluorescence microscopy and biochemical assays are used to show that RUNX1 associates with the human ATP-dependent SWI/SNF chromatin remodeling complex.

Ectopic runx2 expression in mammary epithelial cells disrupts formation of normal acini structure: implications for breast cancer progression.

The transcription factor Runx2 is highly expressed in breast cancer cells compared with mammary epithelial cells and contributes to metastasis. Here we directly show that Runx2 expression promotes a tumor cell phenotype of mammary acini in three-dimensional culture. Human mammary epithelial cells (MCF-10A) form polarized, growth-arrested, acini-like structures with glandular architecture.

The osteogenic transcription factor runx2 controls genes involved in sterol/steroid metabolism, including CYP11A1 in osteoblasts.

Steroid hormones including (1,25)-dihydroxyvitamin D3, estrogens, and glucocorticoids control bone development and homeostasis. We show here that the osteogenic transcription factor Runx2 controls genes involved in sterol/steroid metabolism, including Cyp11a1, Cyp39a1, Cyp51, Lss, and Dhcr7 in murine osteoprogenitor cells. Cyp11a1 (P450scc) encodes an approximately 55-kDa mitochondrial enzyme that catalyzes side-chain cleavage of cholesterol and is rate limiting for steroid hormone biosynthesis.

Organization, integration, and assembly of genetic and epigenetic regulatory machinery in nuclear microenvironments: implications for biological control in cancer.

There is growing awareness that the fidelity of gene expression necessitates coordination of transcription factor metabolism and organization of genes and regulatory proteins within the three-dimensional context of nuclear architecture. The regulatory machinery that governs genetic and epigenetic control of gene expression is compartmentalized in nuclear microenvironments. Temporal and spatial parameters of regulatory complex organization and assembly are functionally linked to biological control and are compromised with the onset and progression of tumorigenesis.

Transcription-factor-mediated epigenetic control of cell fate and lineage commitment.

Epigenetic control is required to maintain competency for the activation and suppression of genes during cell division. The association between regulatory proteins and target gene loci during mitosis is a parameter of the epigenetic control that sustains the transcriptional regulatory machinery that perpetuates gene-expression signatures in progeny cells. The mitotic retention of phenotypic regulatory factors with cell cycle, cell fate, and tissue-specific genes supports the coordinated control that governs the proliferation and differentiation of cell fate and lineage commitment.

A Runx2 threshold for the cleidocranial dysplasia phenotype.

Cleidocranial dysplasia (CCD) in humans is an autosomal-dominant skeletal disease that results from mutations in the bone-specific transcription factor RUNX2 (CBFA1/AML3). However, distinct RUNX2 mutations in CCD do not correlate with the severity of the disease. Here we generated a new mouse model with a hypomorphic Runx2 mutant allele (Runx2(neo7)), in which only part of the transcript is processed to full-length (wild-type) Runx2 mRNA.

Runx2 transcriptional activation of Indian Hedgehog and a downstream bone metastatic pathway in breast cancer cells.

Runx2, required for bone formation, is ectopically expressed in breast cancer cells. To address the mechanism by which Runx2 contributes to the osteolytic disease induced by MDA-MB-231 cells, we investigated the effect of Runx2 on key components of the "vicious cycle" of transforming growth factor beta (TGFbeta)-mediated tumor growth and osteolysis. We find that Runx2 directly up-regulates Indian Hedgehog (IHH) and colocalizes with Gli2, a Hedgehog signaling molecule.

Specific residues of RUNX2 are obligatory for formation of BMP2-induced RUNX2-SMAD complex to promote osteoblast differentiation.

BMP2 signaling and RUNX2 regulatory pathways converge for transcriptional control of bone formation in vivo. SMAD proteins are recruited to RUNX2 regulatory complexes via an overlapping nuclear matrix targeting signal/Smad interacting domain sequence (391-432) in Runx2. To establish the contribution of RUNX2-SMAD interaction to osteoblastogenesis, we characterized a number of point mutants.

Runx2 regulates G protein-coupled signaling pathways to control growth of osteoblast progenitors.

Runt-related transcription factor 2 (Runx2) controls lineage commitment, proliferation, and anabolic functions of osteoblasts as the subnuclear effector of multiple signaling axes (e.g. transforming growth factor-beta/BMP-SMAD, SRC/YES-YAP, and GROUCHO/TLE).

Genetic and epigenetic regulation in nuclear microenvironments for biological control in cancer.

The regulatory machinery that governs genetic and epigenetic control of gene expression is compartmentalized in nuclear microenvironments. Temporal and spatial parameters of regulatory complex organization and assembly are functionally linked to biological control and are compromised with the onset and progression of tumorigenesis providing a novel platform for cancer diagnosis and treatment.

Chromatin immunoprecipitation assays: application of ChIP-on-chip for defining dynamic transcriptional mechanisms in bone cells.

Normal cell growth and differentiation of bone cells requires the sequential expression of cell type specific genes to permit lineage specification and development of cellular phenotypes. Transcriptional activation and repression of distinct sets of genes support the anabolic functions of osteoblasts and the catabolic properties of osteoclasts. Furthermore, metastasis of tumors to the bone environment is controlled by transcriptional mechanisms.