The synthetic molecule stauprimide impairs cell growth and migration in triple-negative breast cancer.

Stauprimide, a semi-synthetic derivative of staurosporine, is known mainly for its potent differentiation-enhancing properties in embryonic stem cells. Here, we studied the effects of stauprimide in cell growth and migration of triple-negative breast cancer cells in vitro, evaluating its potential antitumoral activity in an orthotopic mouse model of breast cancer in vivo. Our results from survival curves, EdU incorporation, cell cycle analysis and annexin-V detection in MDA-MB-231 cells indicated that stauprimide inhibited cell proliferation, arresting cell cycle in G2/M without induction of apoptosis. A decrease in the migratory capability of MDA-MB-231 was also assessed in response to stauprimide. In this work we pointed to a mechanism of action of stauprimide involving the modulation of ERK1/2, Akt and p38 MAPK signalling pathways, and the downregulation of MYC in MDA-MB-231 cells. In addition, orthotopic MDA-MB-231 xenograft and 4T1 syngeneic models suggested an effect of stauprimide in vivo, increasing the necrotic core of tumors and reducing metastasis in lung and liver of mice. Together, our results point to the promising role of stauprimide as a putative therapeutic agent in triple-negative breast cancer.

Cirugía Mayor Ambulatoria y Atención Primaria / Ambulatory surgery and primary care

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Non-invasive monitoring of hypoxia-inducible factor activation by optical imaging during antiangiogenic treatment in a xenograft model of ovarian carcinoma.

Targeting the hypoxia response pathway and angiogenesis are two promising therapeutic strategies for cancer treatment. Their use as single strategies has important limitations. Thus, development of combined regimens has become an important step toward improving therapeutic efficacy. Also, non-invasive monitoring of the response to targeted biological therapies, as well as determination of the optimal schedule for combination regimens has become an active field of research over the last five years, with relevance for both preclinical and clinical settings. Here, we used an optical imaging method to non-invasively monitor the functional changes in HIF activity in response to antiangiogenic treatment in a xenograft model of human ovarian carcinoma. A bioluminescent reporter construct containing nine copies of the hypoxia response element upstream of the luciferase gene (9xHRE-luciferase) was characterized in vitro in a panel of tumor cell lines and in vivo in a subcutaneous xenograft model of ovarian carcinoma by means of optical imaging. We showed that in OVCAR-3 subcutaneous xenografts, the most abrupt change in the HIF functional reporter occurs before the onset of massive tumor growth. However, this system failed to detect hypoxia induced upon antiangiogenic treatment due to the compensating effects of increased hypoxia and decreased tumor cell viability caused by imbalanced neovascularization vs. tumor expansion. Therefore, the readout based on HIF functional reporter could be conditioned by the dynamics of tumor growth and angiogenesis, which is highly variable depending on the tumor type, tumor model and stage of progression.

DUSP1/MKP1 promotes angiogenesis, invasion and metastasis in non-small-cell lung cancer.

DUSP1/MKP1 is a dual-specific phosphatase that regulates MAPKs activity, with an increasingly recognized role in tumor biology. To understand more about the involvement of DUSP1 in lung cancer, we performed gene expression analyses of parental and DUSP1-interfered H460 non-small-cell lung cancer (NSCLC) cells. Downregulation of DUSP1 induced changes in the expression levels of genes involved in specific biological pathways, including angiogenesis, MAP kinase phosphatase activity, cell-cell signaling, growth factor and tyrosine-kinase receptor activity. Changes in the expression of some of these genes were due to modulation of c-Jun-N-terminal kinase and/or p38 activity by DUSP1. Complementary functional assays were performed to focus on the implication of DUSP1 in angiogenesis and metastasis. In H460 cells, interference of DUSP1 resulted in a diminished capacity to invade through Matrigel, to grow tumors in nude mice and also to induce metastasis through tail-vein injection. Furthermore, the angiogenic potential of H460 cells was also impaired, correlating with a decrease in VEGFC production and indicating that DUSP1 could be required to induce angiogenesis. Finally, we studied whether a similar relationship occurred in patients. In human NSCLC specimens, DUSP1 was mainly expressed in those tumor cells close to CD31 vascular structures and a statistically significant correlation was found between VEGFC and DUSP1 expression. Overall, these results provide evidence for a role of DUSP1 in angiogenesis, invasion and metastasis in NSCLC.

Following up tumour angiogenesis: from the basic laboratory to the clinic

Preceded by three decades of intense basic research on tumour angiogenesis, we are assisting to the translation of anti-antiangiogenic therapies as medical oncologists are increasingly using pioneering anti-angiogenic drugs in combination with standard treatments. While basic knowledge in the field of angiogenesis is reaching maturity and our level of understanding of the complex process of vessel development and growth in health and disease has been enriched at the molecular and cellular levels, the translation of this knowledge to the clinic is still in its infancy. Identifying the most suitable drugs, and the optimal dosage and schedule, as well as monitoring patients' responses to anti-angiogenic therapy, remain challenging issues that currently limit the benefit of this new therapeutic approach in cancer. This review will focus on a comprehensive description of the experimental assays in which angiogenesis research has been founded and how the different assays complement and provide relevant information for the task of characterising the angiogenic properties of diverse tumours, giving us a variety of tools to follow up tumour angiogenesis in research models. Following up tumour angiogenesis in patients and their response to antiangiogenic therapy is a more challenging task that will benefit in the near future from the use of non-invasive imaging methods as well as molecular and cellular biomarkers of angiogenesis suitable for clinical oncology. As both the design of the anti-angiogenic therapies and monitoring of the response are improved in the coming years to properly tailor them to the angiogenic profile of every patient, we hope to achieve increasing response and benefit of including antiangiogenic drugs as standard in cancer therapy (AU)

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Ornithine decarboxylase activity and urea in liver of late-pregnant rats. Effect of streptozotocin-induced diabetes.

It has been suggested that the induction of ornithine decarboxylase (ODC) activity during pregnancy might contribute to the low ureagenic flux that enables the pregnant mother to spare nitrogen and support growth. Thus, we have studied the ODC activity, and urea and polyamine levels in livers of virgin and 21-day pregnant rats, either in a basal state or after the induction of ureagenesis by inducing diabetes in rats by streptozotocin injection. Diabetes led to a marked increase in circulating and liver urea levels in virgin rats. This response was significantly reduced in late-pregnant animals. Diabetes did not modify ODC activity in pregnant rats, which showed much lower activities than their virgin controls. Diabetes caused a depletion of the liver spermine content in pregnant rats. Spermidine levels were higher in both groups of pregnant animals than in their respective controls. Our results suggest first that the mechanisms contributing to spare nitrogen in the pregnant mother are likely to be present in diabetic pregnant animals and, second, that ODC does not mediate the metabolic adaptations leading to a low ureagenic flux and a higher nitrogen retention at the last stage of pregnancy.

Effect of epidermal growth factor on ornithine decarboxylase activity and urea synthesis in isolated rat hepatocytes.

Ornithine decarboxylase (ODC) activity is induced by protein-synthesis independent mechanisms in freshly isolated rat hepatocytes, incubated either without or with a mixture of amino acids in the incubation medium. Urea synthesis rates were two- to three-fold higher in those hepatocytes incubated in the presence of amino acids that in those lacking amino acids in the medium. Epidermal growth factor (EGF) delayed ODC induction, but only in the presence of amino acids. EGF significantly decreased ureagenesis when hepatocytes were incubated in the presence of amino acids and only endogenous substrates were available. No evidence of any link between ODC induction and urea synthesis was found.

Involvement of catecholamines in the effect of fasting on hepatic endothelial lipase activity in the rat.

The effect of fasting on hepatic endothelial lipase activity in the liver of adult rats was investigated. We found that, both in male and female rats, fasting produced a progressive decrease of the hepatic endothelial lipase activity. Upon refeeding, the activity returned to control values in 48 h. In isolated livers from fed male rats, a sharp peak of hepatic endothelial lipase activity appeared in the perfusate upon heparin addition. It accounted for 75% of the total activity (heparin-released + residual) of the tissue. Fasting (24 h) decreased the heparin-releasable activity, and this effect was responsible for most of the decrease found in whole tissue. We suggest that the effect might be due to a decreased synthesis and/or secretion of the enzyme by hepatocytes, since isolated hepatocytes from fasted rats, incubated at 37 C, released 65% less activity to the incubation medium than hepatocytes from fed rats. Adrenaline, but not insulin, glucagon, dexamethasone, epidermal growth factor, or T3, decreased the amount of hepatic endothelial lipase activity released by hepatocytes isolated from fed rats. The effect of adrenaline appears to be mediated by alpha 1-receptors since phenylephrine but not isoprenaline reproduced, and prazosin but not propranolol blocked, the effect of the catecholamine. In the presence of cycloheximide, adrenaline also decreased the amount of activity released. We suggest that, in our incubation conditions (up to 3 h), the hormone affects the posttranslational processing of the enzyme. In vivo administration of prazosin blocked the effect of both noradrenaline and fasting on hepatic endothelial lipase activity in whole liver. Those results suggest that catecholamines are involved in the decreased hepatic endothelial lipase activity found in the liver of fasted rats, and points out the role of these hormones in the acute modulation of an enzyme involved in reverse cholesterol transport.

Effect of epidermal growth factor (EGF) on gluconeogenesis in isolated rat hepatocytes. Dependency on the red-ox state of the substrate.

It was found that EGF decreased both the basal- and the glucagon-stimulated gluconeogenesis from lactate alone or from a high lactate/pyruvate ratio and that it enhanced both the basal- and the glucagon-inhibited glucose synthesis from pyruvate alone or from a low lactate/pyruvate ratio. These findings demonstrate that the effect of both EGF and glucagon on glucose production by isolated hepatocytes depends on the red-ox state of the substrate.