Bone morphogenetic protein 4 (BMP4) is required for migration and invasion of breast cancer

Nucleosome positioning and histone modifications define relationships between regulatory elements and nearby gene expression in breast epithelial cells

Background

The precise nature of how cell type specific chromatin structures at enhancer sites affect gene expression is largely unknown. Here we identified cell type specific enhancers coupled with gene expression in two different types of breast epithelial cells, HMEC (normal breast epithelial cells) and MDAMB231 (triple negative breast cancer cell line).

Results

Enhancers were defined by modified neighboring histones [using chromatin immunoprecipitation followed by sequencing (ChIP-seq)] and nucleosome depletion [using formaldehyde-assisted isolation of regulatory elements followed by sequencing (FAIRE-seq)]. Histone modifications at enhancers were related to the expression levels of nearby genes up to 750 kb away. These expression levels were correlated with enhancer status (poised or active), defined by surrounding histone marks. Furthermore, about fifty percent of poised and active enhancers contained nucleosome-depleted regions. We also identified response element motifs enriched at these enhancer sites that revealed key transcription factors (e.g. TP63) likely involved in regulating breast epithelial enhancer-mediated gene expression. By utilizing expression data, potential target genes of more than 600 active enhancers were identified. These genes were involved in proteolysis, epidermis development, cell adhesion, mitosis, cell cycle, and DNA replication.

Conclusions

These findings facilitate the understanding of epigenetic regulation specifically, such as the relationships between regulatory elements and gene expression and generally, how breast epithelial cellular phenotypes are determined by cell type specific enhancers.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-331) contains supplementary material, which is available to authorized users.

Dorsomorphin reverses the mesenchymal phenotype of breast cancer initiating cells by inhibition of bone morphogenetic protein signaling

Increasing evidence supports the theory that tumor growth, homeostasis, and recurrence are dependent on a small subset of cells with stem cell properties, redefined cancer initiating cells (CICs) or cancer stem cells. Bone morphogenetic proteins (BMPs) are involved in cell-fate specification during embryogenesis, in the maintenance of developmental potency in adult stem cells and may contribute to sustain CIC populations in breast carcinoma. Using the mouse A17 cell model previously related to mesenchymal cancer stem cells and displaying properties of CICs, we investigated the role of BMPs in the control of breast cancer cell plasticity. We showed that an autocrine activation of BMP signaling is crucial for the maintenance of mesenchymal stem cell phenotype and tumorigenic potential of A17 cells. Pharmacological inhibition of BMP signaling cascade by Dorsomorphin resulted in the acquisition of epithelial-like traits by A17 cells, including expression of Citokeratin-18 and E-cadherin, through downregulation of Snail and Slug transcriptional factors and Cyclooxygenase-2 (COX2) expression, and in the loss of their stem-features and self-renewal ability. This phenotypic switch compromised A17 cell motility, invasiveness and in vitro tumor growth. These results reveal that BMPs are key molecules at the crossroad between stemness and cancer.

BMP4, a new prognostic factor for glioma

BACKGROUND

The expression status of bone morphogenetic protein 4 (BMP4) in gliomas is still unclear by now. We try to investigate the relationship between BMP4 expression and the biological behavior of gliomas in order to lay a foundation for the management of these tumors.

METHODS

A total of 630 patients with glioma were enrolled in the study from January 2002 to January 2008. The expression status of BMP4 in gliomas was evaluated by RT-PCR and immunohistochemistry. The relationships between BMP4 expression and clinicopathological parameters and between BMP4 expression and prognosis were also studied.

RESULTS

The expression of BMP4 in tumor tissues was significantly lower than that in the paracancer tissues at both mRNA and protein levels (P = 0.01 and 0.001, respectively). Univariate analysis showed that BMP4 expression was closely related to extent of resection, Ki-67 expression, and the WHO grade (P = 0.001, 0.001, and 0.001, respectively), but it was not related to age, sex, or the Karnofsky Performance Status (KPS) score (P = 0.099, 0.472, and 0.201, respectively). Finally, Ki-67 expression and the WHO grade were found to be related to BMP4 expression using logistic regression (P = 0.001 and 0.001, respectively). Interestingly, we found that the expression of BMP4 was significantly related to distant glioma metastasis. Cox regression analysis identified the KPS score, extent of resection, Ki-67 expression, WHO grade, and BMP4 expression as independent prognostic factors (P = 0.044, 0.010, 0.002, 0.001, and 0.001, respectively).

CONCLUSIONS

BMP4 is differentially expressed in glioma patients and is closely related to the biological behavior of gliomas. BMP4 expression was found to be a strong predictor of distant metastasis and postoperative prognosis.

BMP4 inhibits the proliferation of breast cancer cells and induces an MMP-dependent migratory phenotype in MDA-MB-231 cells in 3D environment

Background

Bone morphogenetic protein 4 (BMP4) belongs to the transforming growth factor β (TGF-β) family of proteins. BMPs regulate cell proliferation, differentiation and motility, and have also been reported to be involved in cancer pathogenesis. We have previously shown that BMP4 reduces breast cancer cell proliferation through G1 cell cycle arrest and simultaneously induces migration in a subset of these cell lines. Here we examined the effects of BMP4 in a more physiological environment, in a 3D culture system.

Methods

We used two different 3D culture systems; Matrigel, a basement membrane extract from mouse sarcoma cells, and a synthetic polyethylene glycol (PEG) gel. AlamarBlue reagent was used for cell proliferation measurements and immunofluorescence was used to determine cell polarity. Expression of cell cycle regulators was examined by Western blot and matrix metalloproteinase (MMP) expression by qRT-PCR.

Results

The MCF-10A normal breast epithelial cells formed round acini with correct apicobasal localization of α6 integrin in Matrigel whereas irregular structures were seen in PEG gel. The two 3D matrices also supported dissimilar morphology for the breast cancer cells. In PEG gel, BMP4 inhibited the growth of MCF-10A and the three breast cancer cell lines examined, thus closely resembling the 2D culture conditions, but in Matrigel, no growth inhibition was observed in MDA-MB-231 and MDA-MB-361 cells. Furthermore, BMP4 induced the expression of the cell cycle inhibitor p21 both in 2D and 3D culture, thereby partly explaining the growth arrest. Interestingly, MDA-MB-231 cells formed large branching, stellate structures in response to BMP4 treatment in Matrigel, suggestive of increased cell migration or invasion. This effect was reversed by Batimastat, a broad-spectrum MMP inhibitor, and subsequent analyses showed BMP4 to induce the expression of MMP3 and MMP14, that are thus likely to be responsible for the stellate phenotype.

Conclusions

Taken together, our results show that Matrigel provides a more physiological environment for breast epithelial cells than PEG gel. Moreover, BMP4 partly recapitulates in 3D culture the growth suppressive abilities previously seen in 2D culture and induces an MMP-dependent migratory phenotype in MDA-MB-231 cells.

BMP4 is a novel transcriptional target and mediator of mammary cell migration downstream of the Hippo pathway component TAZ

Since the metastatic progression of cancers is often fatal with limited treatment options, understanding the mechanism of metastasis is imperative for designing novel and targeted therapies. TAZ has been identified as a novel oncogene in both breast and lung cancers and is inhibited by the Hippo signaling pathway. In this study we provide convincing evidence that overexpression of TAZ in a mammary epithelial cell line, MCF10A, leads to enhanced cell migration - a fundamental characteristic of the metastatic progression of cancers. In addition, we identified the secreted growth factor BMP4 as a mediator of TAZ-induced cell migration. TAZ induces BMP4 transcription through the TEAD family of transcription factors, which mediate BMP4 promoter activation through binding to TEAD response element 1 (TRE1). Importantly, BMP4 activation by TAZ also enhances signaling downstream of TAZ, in particular, promoting Smad1/5 intracellular signaling. Functionally, short hairpin RNA-mediated knockdown of BMP4 rescued TAZ-induced cell migration. Our findings have identified a novel TAZ/TEAD/BMP4 signaling axis responsible for cell migration, with future implications in the development of targeted therapeutics for metastatic breast cancers.

Enhanced production of CTGF and IL-11 from highly metastatic hepatoma cells under hypoxic conditions: an implication of hepatocellular carcinoma metastasis to bone

PURPOSE

The biology underlying bone-specific metastasis (BM) of hepatocellular carcinoma (HCC) is poorly understood. The goal of the present study is to further elucidate the molecular and cellular mechanisms underlying HCC with BM.

METHODS

The expression of connective tissue growth factor (CTGF) and interleukin-11 (IL-11) in RNA extracted from 127 formalin-fixed, paraffin-embedded HCC specimens was examined by quantitative real-time polymerase chain reaction. A cellular hypoxic model was established in vitro to investigate CTGF and osteoprotegerin (OPG) expression and roles in hypoxia-induced tumor aggressiveness.

RESULTS

The mean CTGF expression in BM versus non-metastatic samples was 3.63-times higher, and IL-11 expression was detected in 62.5 % (10/16) of BM samples versus only in 18.9 % (21/111) of the non-metastatic ones. Highly metastatic HCC cell lines tended to show strong expression of CTGF and IL-11, but low expression of OPG. Hypoxic stimulation of HCC 97L cells increased the level of CTGF mRNA by 2.80-fold within 1.5 h, and hypoxia-inducible factor-1α mRNA levels in these cells could be increased by stimulation with recombinant CTGF protein. Furthermore, OPG and matrix metalloproteinase-2 and -9 levels were also induced under hypoxic conditions.

CONCLUSIONS

Expression levels of intratumoral CTGF or IL-11 were independent prognostic factors for the development of BM in HCC patients. Tumor hypoxia enhanced the expression of CTGF, which initiates the invasive angiogenesis cascade and enhances expression of many hypoxia-associated genes. Cellular release of OPG may play a role in tumor cell survival. The hypoxia-induced cascade in HCC cells may contribute to invasion and metastasis in vivo.

Altered cytokine gene expression in peripheral blood monocytes across the menstrual cycle in primary dysmenorrhea: a case-control study

Primary dysmenorrhea is one of the most common gynecological complaints in young women, but potential peripheral immunologic features underlying this condition remain undefined. In this paper, we compared 84 common cytokine gene expression profiles of peripheral blood mononuclear cells (PBMCs) from six primary dysmenorrheic young women and three unaffected controls on the seventh day before (secretory phase), and the first (menstrual phase) and the fifth (regenerative phase) days of menstruation, using a real-time PCR array assay combined with pattern recognition and gene function annotation methods. Comparisons between dysmenorrhea and normal control groups identified 11 (nine increased and two decreased), 14 (five increased and nine decreased), and 15 (seven increased and eight decreased) genes with ≥2-fold difference in expression (P<0.05) in the three phases of menstruation, respectively. In the menstrual phase, genes encoding pro-inflammatory cytokines (IL1B, TNF, IL6, and IL8) were up-regulated, and genes encoding TGF-β superfamily members (BMP4, BMP6, GDF5, GDF11, LEFTY2, NODAL, and MSTN) were down-regulated. Functional annotation revealed an excessive inflammatory response and insufficient TGF-β superfamily member signals with anti-inflammatory consequences, which may directly contribute to menstrual pain. In the secretory and regenerative phases, increased expression of pro-inflammatory cytokines and decreased expression of growth factors were also observed. These factors may be involved in the regulation of decidualization, endometrium breakdown and repair, and indirectly exacerbate primary dysmenorrhea. This first study of cytokine gene expression profiles in PBMCs from young primary dysmenorrheic women demonstrates a shift in the balance between expression patterns of pro-inflammatory cytokines and TGF-β superfamily members across the whole menstrual cycle, underlying the peripheral immunologic features of primary dysmenorrhea.

Bone morphogenetic protein 4-a fascinating regulator of cancer cell behavior

Bone morphogenetic proteins (BMPs) are extracellular signaling molecules that belong to the transforming growth factor β (TGFβ) superfamily and are well-known for their indispensable roles in vertebrate development. In recent years, important new information has been generated on the contribution of BMP family members, such as BMP4, in cancer pathogenesis. First of all, BMP4 gene variants have been shown to predispose to colorectal cancer. In sporadic cancer, BMP4 expression levels are commonly altered in many tumor types and have been linked to patient prognosis in hepatocellular and ovarian cancer. In terms of BMP4 function in cancer cells, the majority of studies demonstrate that BMP4 suppresses cell growth both in vitro and in vivo, and at the same time is able to induce migration, invasion, and epithelial-mesenchymal transition. These latter phenotypes are typically associated with cancer metastasis and progression, and thus BMP4 seems to elicit effects that are both detrimental and beneficial for the cancer cells. The functional effects of BMP4 are not restricted to the control of cell proliferation and mobility, since it also contributes to the regulation of differentiation, apoptosis, and angiogenesis. The latter is especially intriguing since the formation of new blood vessels is a prerequisite for sustained tumor growth and cancer progression. Mainly due to its growth suppressive abilities, BMP4 has been suggested as a possible therapeutic target in cancer cells. However, the other functional characteristics of BMP4, especially the promotion of cell mobility, make such strategies less appealing. Improved knowledge of the downstream mediators of BMP4 effects in cancer cells may allow dissection of the different BMP4-induced phenotypes and thereby generation of specific targeted therapies.