MicroRNA-200 Family Members Differentially Regulate Morphological Plasticity and Mode of Melanoma Cell Invasion

A functional role of microRNAs (miRNAs or miRs) in neoplasia and metastasis is becoming clear, and the miR-200 family has received much attention for potentially regulating tumor progression. The miRNAs of this family have been shown to suppress epithelial-mesenchymal transition, and their down-regulation in some tumors promotes invasion and metastasis. Interestingly, while miR-200 is down-regulated in some cancers, it is up-regulated in others.We show that levels of miR-200 are increased in melanoma cell lines compared to normal melanocytes and that miR-200 family members play a role in determining modes of tumor cell migration. Individual tumor cells can invade in either elongated, "mesenchymal-type" or rounded, "amoeboid-like" modes and these two modes of invasion are inter-convertible [1]. In melanoma cell lines, expression of miR-200 members does not suppress invasion but rather leads to a switch between modes of invasion. MicroRNA-200c results in a higher proportion of cells adopting the rounded, amoeboid-like mode of invasion, while miR-200a results in a protrusion-associated elongated mode of invasion. Functional target identification studies suggest that the morphological effects of miR-200c may be mediated by reduced expression of MARCKS, which has been linked to formation of cell protrusions. In contrast miR-200a reduces actomyosin contractility, a feature of rounded morphology.Overall our findings call into question the general role of miR-200 in suppressing invasion and metastasis, and highlight novel distinguishing characteristics of individual miR-200 family members

A guide to mechanobiology: Where biology and physics meet

AbstractCells actively sense and process mechanical information that is provided by the extracellular environment to make decisions about growth, motility and differentiation. It is important to understand the underlying mechanisms given that deregulation of the mechanical properties of the extracellular matrix (ECM) is implicated in various diseases, such as cancer and fibrosis. Moreover, matrix mechanics can be exploited to program stem cell differentiation for organ-on-chip and regenerative medicine applications. Mechanobiology is an emerging multidisciplinary field that encompasses cell and developmental biology, bioengineering and biophysics. Here we provide an introductory overview of the key players important to cellular mechanobiology, taking a biophysical perspective and focusing on a comparison between flat versus three dimensional substrates. This article is part of a Special Issue entitled: Mechanobiology

Neutrophil-Mediated Experimental Metastasis Is Enhanced by VEGFR Inhibition in a Zebrafish Xenograft Model

Inhibition of VEGF signalling effectively suppresses localized tumour growth but accelerates tumour invasiveness and micrometastasis by unknown mechanisms. To study the dynamic and reciprocal interactions between tumour cells and their microenvironment during these processes, we established a xenograft model by injecting tumour cells into the blood circulation of transparent zebrafish embryos. This reproducibly results in rapid simultaneous formation of a localized tumour and experimental micrometastasis, allowing time-resolved imaging of both processes at single-cell resolution within 1 week. The tumour vasculature was initiated de novo by remodelling of primitive endothelial cells into a functional network. Roles of myeloid cells in critical tumourigenesis steps such as vascularization and invasion were revealed by genetic and pharmaceutical approaches. We discovered that the physiological migration of neutrophils controlled tumour invasion by conditioning the collagen matrix and forming the metastatic niche, as detected by two-photon confocal microscopy and second harmonic generation. Administration of VEGFR inhibitors blocked tumour vascularization and a localized tumour growth but enhanced migration of neutrophils, which in turn promoted tumour invasion and formation of micrometastasis. This demonstrates the in vivo cooperation between VEGF signalling and myeloid cells in metastasis and provides a new mechanism underlying the recent findings that VEGFR targeting can promote tumour invasiveness

Automated Whole Animal Bio-Imaging Assay for Human Cancer Dissemination

A quantitative bio-imaging platform is developed for analysis of human cancer dissemination in a short-term vertebrate xenotransplantation assay. Six days after implantation of cancer cells in zebrafish embryos, automated imaging in 96 well plates coupled to image analysis algorithms quantifies spreading throughout the host. Findings in this model correlate with behavior in long-term rodent xenograft models for panels of poorly- versus highly malignant cell lines derived from breast, colorectal, and prostate cancer. In addition, cancer cells with scattered mesenchymal characteristics show higher dissemination capacity than cell types with epithelial appearance. Moreover, RNA interference establishes the metastasis-suppressor role for E-cadherin in this model. This automated quantitative whole animal bio-imaging assay can serve as a first-line in vivo screening step in the anti-cancer drug target discovery pipeline

BMP-7 inhibits TGF-β-induced invasion of breast cancer cells through inhibition of integrin β3 expression

BACKGROUND The transforming growth factor (TGF)-β superfamily comprises cytokines such as TGF-β and Bone Morphogenetic Proteins (BMPs), which have a critical role in a multitude of biological processes. In breast cancer, high levels of TGF-β are associated with poor outcome, whereas inhibition of TGF-β-signaling reduces metastasis. In contrast, BMP-7 inhibits bone metastasis of breast cancer cells. METHODS In this study, we investigated the effect of BMP-7 on TGF-β-induced invasion in a 3 dimensional invasion assay. RESULTS BMP-7 inhibited TGF-β-induced invasion of the metastatic breast cancer cell line MCF10CA1a, but not of its premalignant precursor MCF10AT in a spheroid invasion model. The inhibitory effect appears to be specific for BMP-7, as its closest homolog, BMP-6, did not alter the invasion of MCF10CA1a spheroids. To elucidate the mechanism by which BMP-7 inhibits TGF-β-induced invasion, we analyzed invasion-related genes. BMP-7 inhibited TGF-β-induced expression of integrin α(v)β(3) in the spheroids. Moreover, targeting of integrins by a chemical inhibitor or knockdown of integrin β(3) negatively affected TGF-β-induced invasion. On the other hand, overexpression of integrin β(3) counteracted the inhibitory effect of BMP7 on TGF-β-induced invasion. CONCLUSION Thus, BMP-7 may exert anti-invasive actions by inhibiting TGF-β-induced expression of integrin β(3).Prostatic carcinom

No preclinical rationale for IGF1R directed therapy in chondrosarcoma of bone

Background: Chondrosarcoma is a malignant cartilage forming bone tumour for which no effective systemic treatment is available. Previous studies illustrate the need for a better understanding of the role of the IGF pathway in chondrosarcoma to determine if it can be a target for therapy, which was therefore explored in this study. Methods: Expression of mediators of IGF1R signalling and phosphorylation status of IRS1 was determined in chondrosarcoma cell lines by qRT-PCR and western blot. The effect of activation and inhibition of IGF1R signalling on downstream targets was assessed by western blot. Ten chondrosarcoma cell lines were treated with OSI-906 (IGF1R and IR dual inhibitor) after which cell proliferation and migration were determined by a viability assay and the xCELLigence system, respectively. In addition, four chondrosarcoma cell lines were treated with a combination of doxorubicin and OSI-906. By immunohistochemistry, IGF1R expression levels were determined in tissue microarrays of 187 cartilage tumours and ten paraffin embedded cell lines. Results: Mediators of IGF1R signalling are heterogeneously expressed and phosphorylated IRS1 was detected in 67 % of the tested chondrosarcoma cell lines, suggesting that IGF1R signalling is active in a subset of chondrosarcoma cell lines. In the cell lines with phosphorylated IRS1, inhibition of IGF1R signalling decreased phosphorylated Akt levels and increased IGF1R expression, but it did not influence MAPK or S6 activity. In line with these findings, treatment with IGF1R/IR inhibitors did not impact proliferation or migration in any of the chondrosarcoma cell lines, even upon stimulation with IGF1. Although synergistic effects of IGF1R/IR inhibition with doxorubicin are described for other cancers, our results demonstrate that this was not the case for chondrosarcoma. In addition, we found minimal IGF1R expression in primary tumours in contrast to the high expression detected in chondrosarcoma cell lines, even if both were derived from the same tumour, suggesting that in vitro culturing upregulates IGF1R expression. Conclusions: The results from this study indicate that the IGF pathway is not essential for chondrosarcoma growth, migration or chemoresistance. Furthermore, IGF1R is only minimally expressed in chondrosarcoma primary tumours. Therefore, the IGF pathway is not expected to be an effective therapeutic target for chondrosarcoma of bone. Electronic supplementary material The online version of this article (doi:10.1186/s12885-016-2522-8) contains supplementary material, which is available to authorized users

IGF1R signaling drives antiestrogen resistance through PAK2/PIX activation in luminal breast cancer

Antiestrogen resistance in estrogen receptor positive (ER+) breast cancer is associated with increased expression and activity of insulin-like growth factor 1 receptor (IGF1R). Here, a kinome siRNA screen has identified 10 regulators of IGF1R-mediated antiestrogen with clinical significance. These include the tamoxifen resistance suppressors BMPR1B, CDK10, CDK5, EIF2AK1, and MAP2K5, and the tamoxifen resistance inducers CHEK1, PAK2, RPS6KC1, TTK, and TXK. The p21-activated kinase 2, PAK2, is the strongest resistance inducer. Silencing of the tamoxifen resistance inducing genes, particularly PAK2, attenuates IGF1R-mediated resistance to tamoxifen and fulvestrant. High expression of PAK2 in ER+ metastatic breast cancer patients is correlated with unfavorable outcome after first-line tamoxifen monotherapy. Phospho-proteomics has defined PAK2 and the PAK-interacting exchange factors PIXα/β as downstream targets of IGF1R signaling, which are independent from PI3K/ATK and MAPK/ERK pathways. PAK2 and PIXα/β modulate IGF1R signaling-driven cell scattering. Targeting PIXα/β entirely mimics the effect of PAK2 silencing on antiestrogen re-sensitization. These data indicate PAK2/PIX as an effector pathway in IGF1R-mediated antiestrogen resistance