Vascular endothelial growth factor-A (VEGF), a potent angiogenic factor, is also implicated in self-renewal in several normal tissue types. VEGF has been shown to drive malignant stem cells but ...mechanisms thereof and tumor types affected are not fully characterized. Here, we show VEGF promotes breast and lung cancer stem cell (CSC) self-renewal via VEGF receptor-2 (VEGFR-2)/STAT3-mediated upregulation of Myc and Sox2. VEGF increased tumor spheres and aldehyde dehydrogenase activity, both proxies for stem cell function in vitro, in triple-negative breast cancer (TNBC) lines and dissociated primary cancers, and in lung cancer lines. VEGF exposure before injection increased breast cancer-initiating cell abundance in vivo yielding increased orthotopic tumors, and increased metastasis from orthotopic primaries and following tail vein injection without further VEGF treatment. VEGF rapidly stimulated VEGFR-2/JAK2/STAT3 binding and activated STAT3 to bind MYC and SOX2 promoters and induce their expression. VEGFR-2 knockdown or inhibition abrogated VEGF-mediated STAT3 activation, MYC and SOX2 induction and sphere formation. Notably, knockdown of either STAT3, MYC or SOX2 impaired VEGF-upregulation of pSTAT3, MYC and SOX2 expression and sphere formation. Each transcription factor, once upregulated, appears to promote sustained activation of the others, creating a feed-forward loop to drive self-renewal. Thus, in addition to angiogenic effects, VEGF promotes tumor-initiating cell self-renewal through VEGFR-2/STAT3 signaling. Analysis of primary breast and lung cancers (>1300 each) showed high VEGF expression, was prognostic of poor outcome and strongly associated with STAT3 and MYC expression, supporting the link between VEGF and CSC self-renewal. High-VEGF tumors may be most likely to escape anti-angiogenics by upregulating VEGF, driving CSC self-renewal to re-populate post-treatment. Our work highlights the need to better define VEGF-driven cancer subsets and supports further investigation of combined therapeutic blockade of VEGF or VEGFR-2 and JAK2/STAT3.
The iron press was operated manually by a simple toggle action, unlike the more complex lever mechanism of the Columbian Press. Albion presses were primarily used for commercial book orienting until ...the middle of the 19th century. Thereafter they were mostly used for proofing and private commercial work.
Abstract
The cannabinoid CB
2
receptor (CB
2
R) represents a promising therapeutic target for various forms of tissue injury and inflammatory diseases. Although numerous compounds have been developed ...and widely used to target CB
2
R, their selectivity, molecular mode of action and pharmacokinetic properties have been poorly characterized. Here we report the most extensive characterization of the molecular pharmacology of the most widely used CB
2
R ligands to date. In a collaborative effort between multiple academic and industry laboratories, we identify marked differences in the ability of certain agonists to activate distinct signalling pathways and to cause off-target effects. We reach a consensus that HU910, HU308 and JWH133 are the recommended selective CB
2
R agonists to study the role of CB
2
R in biological and disease processes. We believe that our unique approach would be highly suitable for the characterization of other therapeutic targets in drug discovery research.
The completion of the draft sequence of the rhesus macaque genome allowed us to study the genomic composition and evolution of transposable elements in this representative of the Old World monkey ...lineage, a group of diverse primates closely related to humans. The L1 family of long interspersed elements appears to have evolved as a single lineage, and Alu elements have evolved into four currently active lineages. We also found evidence of elevated horizontal transmissions of retroviruses and the absence of DNA transposon activity in the Old World monkey lineage. In addition, ~100 precursors of composite SVA (short interspersed element, variable number of tandem repeat, and Alu) elements were identified, with the majority being shared by the common ancestor of humans and rhesus macaques. Mobile elements compose roughly 50% of primate genomes, and our findings illustrate their diversity and strong influence on genome evolution between closely related species.
More effective, less toxic treatments for recurrent ovarian cancer are needed. Although more than 60% of ovarian cancers express the estrogen receptor (ER), ER-targeted drugs have been disappointing ...due to drug resistance. In other estrogen-sensitive cancers, estrogen activates Src to phosphorylate p27 promoting its degradation and increasing cell-cycle progression. Because Src is activated in most ovarian cancers, we investigated whether combined Src and ER blockade by saracatinib and fulvestrant would circumvent antiestrogen resistance.
ER and Src were assayed in 338 primary ovarian cancers. Dual ER and Src blockade effects on cell cycle, ER target gene expression, and survival were assayed in ERα+ ovarian cancer lines, a primary human ovarian cancer culture in vitro, and on xenograft growth.
Most primary ovarian cancers express ER. Src activity was greater in ovarian cancer lines than normal epithelial lines. Estrogen activated Src, ER-Src binding, and ER translocation from cytoplasm to nucleus. Estrogen-mediated mitogenesis was via ERα, not ERβ. While each alone had little effect, combined saracatinib and fulvestrant increased p27 and inhibited cyclin E-Cdk2 and cell-cycle progression. Saracatinib also impaired induction of ER-target genes c-Myc and FOSL1; this was greatest with dual therapy. Combined therapy induced autophagy and more effectively inhibited ovarian cancer xenograft growth than monotherapy.
Saracatinib augments effects of fulvestrant by opposing estrogen-mediated Src activation and target gene expression, increasing cell-cycle arrest, and impairing survival, all of which would oppose antiestrogen resistance in these ER+ ovarian cancer models. These data support further preclinical and clinical evaluation of combined fulvestrant and saracatinib in ovarian cancer.
The cannabinoid CB sub(2) receptor (CB sub(2)R) represents a promising therapeutic target for various forms of tissue injury and inflammatory diseases. Although numerous compounds have been developed ...and widely used to target CB sub(2)R, their selectivity, molecular mode of action and pharmacokinetic properties have been poorly characterized. Here we report the most extensive characterization of the molecular pharmacology of the most widely used CB sub(2)R ligands to date. In a collaborative effort between multiple academic and industry laboratories, we identify marked differences in the ability of certain agonists to activate distinct signalling pathways and to cause off-target effects. We reach a consensus that HU910, HU308 and JWH133 are the recommended selective CB sub(2)R agonists to study the role of CB sub(2)R in biological and disease processes. We believe that our unique approach would be highly suitable for the characterization of other therapeutic targets in drug discovery research.
1
We have characterized the 5‐hydroxytryptamine (5‐HT)‐induced calcium signalling in endothelial cells from the human pulmonary artery. Using RT‐PCR we show, that of all cloned G‐protein coupled 5‐HT ...receptors, these cells express only 5‐HT1Dβ, 5‐HT2B and little 5‐HT4 receptor mRNA.
2
In endothelial cells 5‐HT inhibits the formation of adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) via 5‐HT1Dβ receptors but fails to activate phosphoinositide (PI) turnover. However, the latter pathway is strongly activated by histamine.
3
Despite the lack of detectable inositol phosphate (IP) formation in human pulmonary artery endothelial cells, 5‐HT (pD2 = 5.82 ± 0.06, n = 6) or the selective 5‐HT2 agonist, 1‐(2,5‐dimethoxy‐4‐ iodophenyl)‐2‐aminopropane (DOI) (pD2 = 5.66 ± 0.03, n = 7) elicited transient calcium signals comparable to those evoked by histamine (pD2 = 6.44 ± 0.01, n = 7). Since 5‐HT2A and 5‐HT2C receptor mRNAs are not detectable in pulmonary artery endothelial cells, activation of 5‐HT2B receptors is responsible for the transient calcium release. The calcium transients are independent of the inhibition of adenylate cyclase, since DOI does not stimulate 5‐HT1Dβ receptors.
4
Both, the 5‐HT‐ and histamine‐stimulated calcium signals were also observed when the cells were placed in calcium‐free medium. This indicates that 5‐HT triggers calcium release from intracellular stores.
5
Heparin is an inhibitor of the IP3‐activated calcium release channels on the endoplasmic reticulum. Intracellular infusion of heparin through patch pipettes in voltage clamp experiments failed to block 5‐ HT‐induced calcium signals, whereas it abolished the histamine response. This supports the conclusion that the 5‐HT‐induced calcium release is independent of IP3 formation.
6
Unlike the histamine response, the 5‐HT response was sensitive to micromolar concentrations of ryanodine and, to a lesser extent, ruthenium red. This implies that 5‐HT2B receptors trigger calcium release from a ryanodine‐sensitive calcium pool.
7
It has been postulated that cyclic ADP‐ribose (cADPR) is a soluble second messenger which activates ryanodine receptors. However, calcium signals similar to the 5‐HT response could not be elicited by intracellular infusion with cADPR. Furthermore, the subsequent application of 5‐HT or DOI elicited a calcium signal that was not affected by the above pretreatment.
8
We conclude that human 5‐HT2B receptors stimulate calcium release from intracellular stores through a novel pathway, which involves activation of ryanodine receptors, and is independent of PI‐hydrolysis and cADPR.
St. John's wort (Hypericum perforatum L.) is widely used for the treatment of mild to moderately severe depression. However, the nature of its active principles and the exact mode of antidepressant ...action are still unknown. It has been suggested repeatedly in preclinical and clinical studies that the content of the acylphloroglucinol hyperforin decisively contributes to the antidepressant efficacy of St. John's wort extracts. Experimental studies in vivo also indicate that the naphthodianthrone hypericin may reduce the activity of the hypothalamic-pituitary-adrenal axis. Exacerbated hypothalamic-pituitary-adrenal activity has often been associated with depressive states in patients. Corticotropin-releasing factor (CRF) seems to be a major determinant in the regulation of the hypothalamic-pituitary-adrenal activity via activation of CRF(1) receptors. In the present study, we investigated the CRF(1) receptor antagonist activity of three main constituents of St. John's wort (hypericin, pseudohypericin and hyperforin) by measuring their effect on CRF-stimulated cAMP formation in recombinant Chinese hamster ovary (CHO) cells. As a selectivity test, the compounds were also tested against calcitonin in the same cells. Of the three compounds tested, only pseudohypericin selectively antagonised CRF (K(B) 0.76 microM). Hypericin and hyperforin affected both CRF and calcitonin with similar potencies and the same type of behaviour (competitive antagonism for hypericin, noncompetitive for hyperforin). It is concluded that pseudohypericin is the only real CRF(1) receptor antagonist of the three constituents tested. In addition, evidence is provided that beside hyperforin, both pseudohypericin and hypericin are implicated in the antidepressant efficacy of St. John's wort.
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