ABSTRACT
The original version of this Article contained errors in Fig. 8. In panel a, the labels 'VEGF', 'Notch', 'p21', and 'P-ERK' were inadvertently omitted. This has been corrected in the PDF and HTML versions of the Article.
ABSTRACT
Appropriate therapeutic modulation of endothelial proliferation and sprouting is essential for the effective inhibition of angiogenesis in cancer or its induction in cardiovascular disease. The current view is that an increase in growth factor concentration, and the resulting mitogenic activity, increases both endothelial proliferation and sprouting. Here, we modulate mitogenic stimuli in different vascular contexts by interfering with the function of the VEGF and Notch signalling pathways at high spatiotemporal resolution in vivo. Contrary to the prevailing view, our results indicate that high mitogenic stimulation induced by VEGF, or Notch inhibition, arrests the proliferation of angiogenic vessels. This is due to the existence of a bell-shaped dose-response to VEGF and MAPK activity that is counteracted by Notch and p21, determining whether endothelial cells sprout, proliferate, or become quiescent. The identified mechanism should be considered to achieve optimal therapeutic modulation of angiogenesis.
Subject(s)
Endothelium, Vascular/drug effects , Mitogens/pharmacology , Neovascularization, Pathologic/drug therapy , Signal Transduction/drug effects , Animals , Cell Proliferation/drug effects , Cyclin-Dependent Kinase Inhibitor p21/genetics , Cyclin-Dependent Kinase Inhibitor p21/metabolism , Endothelium, Vascular/pathology , Human Umbilical Vein Endothelial Cells , Humans , Mice , Mice, Knockout , Neovascularization, Pathologic/pathology , Receptors, Notch/antagonists & inhibitors , Receptors, Notch/metabolism , Retina , Retinal Vessels , Signal Transduction/genetics , Vascular Endothelial Growth Factor A/antagonists & inhibitors , Vascular Endothelial Growth Factor A/metabolismABSTRACT
Abemaciclib is an ATP-competitive, reversible kinase inhibitor selective for CDK4 and CDK6 that has shown antitumor activity as a single agent in hormone receptor positive (HR+) metastatic breast cancer in clinical trials. Here, we examined the mechanistic effects of abemaciclib treatment using in vitro and in vivo breast cancer models. Treatment of estrogen receptor positive (ER+) breast cancer cells with abemaciclib alone led to a decrease in phosphorylation of Rb, arrest at G1, and a decrease in cell proliferation. Moreover, abemaciclib exposure led to durable inhibition of pRb, TopoIIα expression and DNA synthesis, which were maintained after drug removal. Treatment of ER+ breast cancer cells also led to a senescence response as indicated by accumulation of ß-galactosidase, formation of senescence-associated heterochromatin foci, and a decrease in FOXM1 positive cells. Continuous exposure to abemaciclib altered breast cancer cell metabolism and induced apoptosis. In a xenograft model of ER+ breast cancer, abemaciclib monotherapy caused regression of tumor growth. Overall these data indicate that abemaciclib is a CDK4 and CDK6 inhibitor that, as a single agent, blocks breast cancer cell progression, and upon longer treatment can lead to sustained antitumor effects through the induction of senescence, apoptosis, and alteration of cellular metabolism.
ABSTRACT
Improved methods for manipulating and analyzing gene function have provided a better understanding of how genes work during organ development and disease. Inducible functional genetic mosaics can be extraordinarily useful in the study of biological systems; however, this experimental approach is still rarely used in vertebrates. This is mainly due to technical difficulties in the assembly of large DNA constructs carrying multiple genes and regulatory elements and their targeting to the genome. In addition, mosaic phenotypic analysis, unlike classical single gene-function analysis, requires clear labeling and detection of multiple cell clones in the same tissue. Here, we describe several methods for the rapid generation of transgenic or gene-targeted mice and embryonic stem (ES) cell lines containing all the necessary elements for inducible, fluorescent, and functional genetic mosaic (ifgMosaic) analysis. This technology enables the interrogation of multiple and combinatorial gene function with high temporal and cellular resolution.
Subject(s)
Gene Targeting/methods , Animals , Cell Line , Embryonic Stem Cells , Mice , Mice, TransgenicABSTRACT
Fueron estudiados los fetos de la enfermedad de Chagas aguda, durante la preñez en fetos de ratas, particularmente las posibles alteraciones provocadas en las células hepáticas. Fue demostrado un retardo en el crecimiento intrauterino de los fetos, que presentaron peso y longitud menores que el grupo control. A nivel hepático no fue identificada la presencia de nidos de parásitos. Sin embargo, el hígado de los fetos del grupo inoculado presentaba algunos hepatocitos degenerados y con desorganización arquitectural, mientras que los capilares sinusoides estaban congestivos y dilatados. Morfométricamente se verificó la ausencia de alteraciones nucleares en los hepatocitos de los fetos del grupo inoculado. El volumen relativo ocupado por hepatocitos, fue significativamente mayor en el hígado de los fetos del grupo inoculado que en el grupo control, al contrario de lo observado con el volumen relativo de los sinusoides. Así, aún dilatados y congestionados, el volumen relativo de los sinusoides hepáticos en los fetos del grupo inoculado, fue menor que en los controles, reflejando una disminución del número de capilares sinusoides
