Notch4 is required for tumor onset and perfusion

Vascular Cell 04/2013; 5(1):7. DOI: 10.1186/2045-824X-5-7
Source: PubMed

ABSTRACT Background
Notch4 is a member of the Notch family of receptors that is primarily expressed in the vascular endothelial cells. Genetic deletion of Notch4 does not result in an overt phenotype in mice, thus the function of Notch4 remains poorly understood.

We examined the requirement for Notch4 in the development of breast cancer vasculature. Orthotopic transplantation of mouse mammary tumor cells wild type for Notch4 into Notch4 deficient hosts enabled us to delineate the contribution of host Notch4 independent of its function in the tumor cell compartment.

Here, we show that Notch4 expression is required for tumor onset and early tumor perfusion in a mouse model of breast cancer. We found that Notch4 expression is upregulated in mouse and human mammary tumor vasculature. Moreover, host Notch4 deficiency delayed the onset of MMTV-PyMT tumors, wild type for Notch4, after transplantation. Vessel perfusion was decreased in tumors established in Notch4-deficient hosts. Unlike in inhibition of Notch1 or Dll4, vessel density and branching in tumors developed in Notch4-deficient mice were unchanged. However, final tumor size was similar between tumors grown in wild type and Notch4 null hosts.

Our results suggest a novel role for Notch4 in the establishment of tumor colonies and vessel perfusion of transplanted mammary tumors.

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Available from: Maria Costa, Dec 18, 2013
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    • "Higher cancer cell proliferation would require greater vascular nourishment and may induce hypoxic conditions for tumor growth. Knowing that NOTCH4 is primarily expressed in vascular endothelial cells (Costa et al., 2013), the observed higher expression of NOTCH4 with prolonged ischemia in our study is consistent with previous reports (Han et al., 2011; Hiyama et al., 2011; Murphy et al., 2012; Reedijk, 2012; Speiser et al., 2012). High NOTCH expression has also been shown to correlate with poor outcome in breast cancer (Reedijk, 2012; Speiser et al., 2012), with the majority of triple negative breast cancers (TNBC) overexpressing both NOTCH1 and NOTCH4 receptors (Speiser et al., 2012). "
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    ABSTRACT: Background Tissue handling can alter global gene expression potentially affecting the analytical performance of genomic signatures, but such effects have not been systematically evaluated. Methods Tissue samples from 11 previously untreated breast tumors were minced and aliquots were either snap frozen or placed in RNAlater immediately or after 20, 40, 60, 120 or 180 minutes at room temperature. RNA was profiled on Affymetrix HG-U133A arrays. We used probe-set-wise hierarchical models to evaluate the effect of preservation method on transcript expression and linear mixed effects models to assess the effect of cold ischemic delay on the expression of individual probe sets. Gene set enrichment analysis identified pathways overrepresented in the affected transcripts. We combined the levels of 41 most sensitive transcripts to develop an index of ischemic stress. Results Concordance in global gene expression between the baseline and 40 min delay was higher for samples preserved in RNAlater (average concordance correlation coefficient CCC = 0.92 compared to 0.88 for snap frozen). Overall, 481 transcripts (3%) were significantly affected by the preservation method, most of them involved in processes important in cancer. Prolonged cold ischemic delay of up to 3 hours induced marginal global gene expression changes (average CCC=0.90 between baseline and 3 hour delay). However 41 transcripts were significantly affected by cold ischemic delay. Among the induced transcripts were stress response genes, apoptotic response genes; among the downregulated were genes involved in metabolism, protein processing and cell cycle regulation. An index combining the expression levels of these genes was proportional to the cold ischemic delay. Conclusions Prolonged cold ischemia induces significant transcriptional changes in a small subset of transcripts in the tissue. Furthermore, the expression level of about 3% of the transcripts is affected by the preservation method. These sensitive transcripts should not be included in genomic signatures for more reliable analytical performance.
    Molecular oncology 05/2014; 8(3). DOI:10.1016/j.molonc.2014.02.002 · 5.33 Impact Factor
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    • "difference in EGFL7 transcript levels was not due to an overall reduced expression of endothelial-specific genes or a reduction in vascular density (Costa et al., 2013; Nadra et al., 2010; Nichol et al., 2010; van Tuyl et al., 2005). In our study, the reduction in EGFL7 levels in PE was more pronounced as compared to VEGF levels (Fig. 5I), a growth factor whose implication in PE has been extensively studied by others, and found to be either decreased (Cooper et al., 1996; Lyall et al., 1997; Park et al., 2010) or increased (Akercan et al., 2008; Chung et al., 2004; Geva et al., 2002) in PE placentas. "
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    ABSTRACT: The mammalian placenta is the site of nutrient and gas exchange between the mother and fetus, and is comprised of two principal cell types, trophoblasts and endothelial cells. Proper placental development requires invasion and differentiation of trophoblast cells, together with coordinated fetal vasculogenesis and maternal vascular remodeling. Disruption in these processes can result in placental pathologies such as preeclampsia (PE), a disease characterized by late gestational hypertension and proteinuria. Epidermal Growth Factor Like Domain 7 (EGFL7) is a largely endothelial-restricted secreted factor that is critical for embryonic vascular development, and functions by modulating the Notch signaling pathway. However, the role of EGFL7 in placental development remains unknown. In this study, we use mouse models and human placentas to begin to understand the role of EGFL7 during normal and pathological placentation. We show that Egfl7 is expressed by the endothelium of both the maternal and fetal vasculature throughout placental development. Importantly, we uncovered a previously unknown site of EGFL7 expression in the trophoblast cell lineage, including the trophectoderm, trophoblast stem cells, and placental trophoblasts. Our results demonstrate significantly reduced Egfl7 expression in human PE placentas, concurrent with a downregulation of Notch target genes. Moreover, using the BPH/5 mouse model of PE, we show that the downregulation of Egfl7 in compromised placentas occurs prior to the onset of characteristic maternal signs of PE. Together, our results implicate Egfl7 as a possible factor in normal placental development and in the etiology of PE.
    Mechanisms of development 04/2014; 133. DOI:10.1016/j.mod.2014.04.001 · 2.44 Impact Factor
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    ABSTRACT: Notch4 is a divergent member of the Notch family of receptors that is primarily expressed in the vasculature. Its expression implies an important role for Notch4 in the vasculature; however, mice homozygous for the Notch4(d1) knockout allele are viable. Since little is known about the role of Notch4 in the vasculature and how it functions, we further investigated Notch4 in mice and in cultured cells. We and found that the Notch4(d1) allele is not null as it expresses a truncated transcript encoding most of the NOTCH4 extracellular domain. In cultured cells, NOTCH4 did not signal in response to ligand. Moreover, NOTCH4 inhibited signalling from the NOTCH1 receptor. This is the first report of cis-inhibition of signalling by another Notch receptor. The NOTCH4 extracellular domain also inhibits NOTCH1 signalling when expressed in cis, raising the possibility that reported Notch4 phenotypes may not be due to loss of NOTCH4 function. To better address the role of NOTCH4 in vivo, we generated a Notch4 null mouse in which the entire coding region was deleted. Notch4 null mice exhibited slightly delayed vessel growth in the retina, consistent with our novel finding that NOTCH4 protein is expressed in the newly formed vasculature. These findings indicate a role of NOTCH4 in fine-tuning the forming vascular plexus.
    Biochimica et Biophysica Acta 03/2014; 1843(7). DOI:10.1016/j.bbamcr.2014.03.015 · 4.66 Impact Factor
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