Our group is located at the Center of Molecular Biology
“Severo Ochoa” (CBMSO)
– Department
of Molecular Biology in the Universidad
Autónoma de Madrid. The CBMSO is composed of multiple research
laboratories distributed in five scientific areas: Cellular Biology, Developmental
Biology, Neurobiology, Immunology and Virology, and Cellular Signaling.
As a university center, in collaboration with the Department of Molecular
Biology, it organizes practical courses and workshops for researchers and
students. The Department of Molecular Biology has a huge Ph.D. program (including
a joint P.D program with the EMBO lab) covering all aspects of Molecular
Biology offering graduate and postgraduate programs in Cell and Molecular
Biology, Immunology and Molecular Medicine.
A model of cyclooxygenase-2 (COX-2)-mediated
tumor angiogenesis.
Extra and intra-cellular signals leading to tumor progression trigger the expression of COX-2 and pro-angiogenic factors, such as vascular endothelial growth factor (VEGF), in malignant cells (grey), stromal fibroblasts (blue) and endothelial cells (red). These factors induce the production of new blood vessels, which deliver nutrients and oxygen to the malignant cells and, hence, allow tumor growth. Secreted VEGF also stimulates COX-2 expression, thereby triggering prostaglandin (PG) production. PGs can boost VEGF production in a paracrine, intracrine or autocrine fashion, depending on the cell compartment involved. This feedback loop further increases levels of PGs and angiogenic factors, which in turn induce proteolytic enzymes. These facilitate migration and proliferation of endothelial cells, which eventually contribute to an angiogenic response.
Extra and intra-cellular signals leading to tumor progression trigger the expression of COX-2 and pro-angiogenic factors, such as vascular endothelial growth factor (VEGF), in malignant cells (grey), stromal fibroblasts (blue) and endothelial cells (red). These factors induce the production of new blood vessels, which deliver nutrients and oxygen to the malignant cells and, hence, allow tumor growth. Secreted VEGF also stimulates COX-2 expression, thereby triggering prostaglandin (PG) production. PGs can boost VEGF production in a paracrine, intracrine or autocrine fashion, depending on the cell compartment involved. This feedback loop further increases levels of PGs and angiogenic factors, which in turn induce proteolytic enzymes. These facilitate migration and proliferation of endothelial cells, which eventually contribute to an angiogenic response.
Background
Prostaglandin H endoperoxide synthase or cyclooxygenase (COX) catalyzes
the two-step conversion of arachidonic acid (AA) to prostaglandin (PG)-H2
an endoperoxide intermediate that is then converted to other prostaglandins
(PGE2, PGD2, PGF2a, PGI2) and to thromboxanes (TXA2) by specific synthases.
At least two isoforms of the enzyme are expressed in mammalian tissues,
COX-1 and COX-2. COX-1 is constitutively expressed in most mammalian tissues
and is thought to be involved in homeostatic prostanoid biosynthesis. In
contrast, COX-2 is induced by various pro-inflammatory agents, including
cytokines and mitogens being thought to be the predominant isoform involved
in the inflammatory response. In addition, Increasing evidences have lighted
the role played by COX-2 in cancer, especially in colon carcinoma, making
this enzyme an important therapeutic target for cancer prevention. A growing
body of evidence showing a close relationship among expression of COX-2,
Vascular endothelial growth factor (VEGF) and tumor associated angiogenesis
and how they contribute to tumor growth and metastasis. Most of the new
research on anti-inflammatory drugs has been aimed at targeting the COX-2-inducible
production of PGs. Interestingly; these drugs have been proposed to display
novel properties as anti-tumor drugs.
Main achievements in the study of
COX-2 and prostaglandin function
Our group has a wide experience in molecular and cellular immunology, signal
transduction pathways and gene transcription, mostly in T cell and macrophage
activation. We have interested in the study of the signaling pathways involved
in the activation of the immune system, having contributed to this field
with important findings in the regulation of transcription factors NF-kB
and NFAT in T lymphocyte activation process. Concerning to inflammation
research and the biology of eicosanoids, we have described the importance
of the nuclear factor of activated T cells in the transcriptional regulation
of COX-2 in different cell types. Thus, we have demonstrated the involvement
of this transcription factor in the regulation of COX-2 by T cell receptor
activation in T lymphocytes, showing the contribution of Cot and PKCz Serine/threonine
kinases in this process. We have also contributed to a better knowledge
of COX-2 independent NSAIDs immunomodulatory actions through interference
with transcription factor activation.
Our group has recently extended their research
area to include cardiovascular diseases, cancer and angiogenesis. Thus,
in collaboration with Dr. Redondo´s group, we have shown that inhibition
of VEGF -mediated angiogenesis by Cyclosporin A treatment is coincident
with the NFAT-mediated induction of COX-2 in vascular endothelial cells.
We also have recently analyzed the actions of cyclopentenones as 15d-D12,14PGJ2
in the regulation of COX-2 and VEGF in colon carcinoma cells, showing that
inhibition of AP-1 activation by this cyclopentenone plays a crucial role
in the regulation of these genes.
In addition to the studies on the regulation and function of COX-2 and PG
isomerases in colon carcinoma, we are now extending our investigations to
the study of these enzymes and iNOS in macrophages and T lymphocytes using
animal models such as null mice for COX-2, iNOS and TNFa.
References:
1. Iniguez, M. A., Pablos, J. L., Carreira,
P. E., Cabre, F., and Gomez-Reino, J. J. Detection of COX-1 and COX-2 isoforms
in synovial fluid cells from inflammatory joint diseases. Br J Rheumatol,
37: 773-778, 1998.
2. Iniguez, M. A., Punzon, C., and Fresno, M. Induction of cyclooxygenase-2
on activated T lymphocytes: regulation of T cell activation by cyclooxygenase-2
inhibitors. J Immunol, 163: 111-119, 1999.
3. Garcia-Fernandez, L. F., Iniguez, M. A., Eguchi, N., Fresno, M., Urade,
Y., and Munoz, A. Dexamethasone induces lipocalin-type prostaglandin D synthase
gene expression in mouse neuronal cells. J Neurochem, 75: 460-470, 2000.
4. Iniguez, M. A., Martinez-Martinez, S., Punzon, C., Redondo, J. M., and
Fresno, M. An essential role of the nuclear factor of activated T cells
in the regulation of the expression of the cyclooxygenase-2 gene in human
T lymphocytes. J Biol Chem, 275: 23627-23635, 2000.
5. Soler, M., Camacho, M., Escudero, J. R., Iniguez, M. A., and Vila, L.
Human vascular smooth muscle cells but not endothelial cells express prostaglandin
E synthase. Circ Res, 87: 504-507, 2000.
6. de Gregorio, R., Iniguez, M. A., Fresno, M., and Alemany, S. Cot kinase
induces cyclooxygenase-2 expression in T cells through activation of the
nuclear factor of activated T cells. J Biol Chem, 276: 27003-27009, 2001
7. Hernandez, G. L., Volpert, O. V., Iniguez, M. A., Lorenzo, E., Martinez-Martinez,
S., Grau, R., Fresno, M., and Redondo, J. M. Selective inhibition of vascular
endothelial growth factor-mediated angiogenesis by cyclosporin A: roles
of the nuclear factor of activated T cells and cyclooxygenase 2. J Exp Med,
193: 607-620, 2001.
8. Lara-Pezzi, E., Gomez-Gaviro, M. V., Galvez, B. G.,
Mira, E., Iniguez, M. A., Fresno, M., Martinez, A. C., Arroyo, A. G., and
Lopez-Cabrera, M. The hepatitis B virus X protein promotes tumor cell invasion
by inducing membrane-type matrix metalloproteinase-1 and cyclooxygenase-2
expression. J Clin Invest, 110: 1831-1838, 2002.
9. San-Antonio, B., Iniguez, M. A., and Fresno, M. Protein kinase Czeta
phosphorylates nuclear factor of activated T cells and regulates its transactivating
activity. J Biol Chem, 277: 27073-27080, 2002.
10. Iniguez, M. A., Rodriguez, A., Volpert, O. V., Fresno, M., and Redondo,
J. M. Cyclooxygenase-2: a therapeutic target in angiogenesis. Trends Mol
Med, 9: 73-78, 2003.
11. Grau, R., Iniguez, M. A., Fresno, M. Inhibition of Activator Protein
1 Activation, Vascular Endothelial Growth Factor, and Cyclooxygenase-2 Expression
by 15-Deoxy-{Delta}12,14Prostaglandin J2 in Colon Carcinoma Cells: Evidence
for a Redox-Sensitive Peroxisome Proliferator-Activated. Cancer Research,
64: 5162-5171, 2004.
Model for the mechanisms by which 15d-PGJ2 inhibits
COX-2 and VEGF transcriptional activation.
15d-PGJ2 interferes with AP-1 –dependent induction of COX-2 and VEGF transcription at several steps. 15d-PGJ2 reduces the activation/phosphorylation of JNK induced upon cell stimulation (1), what results in diminished activation and phosphorylation of c-Jun (2) reducing its transactivation activity. Besides, this cyclopentenone inhibits the binding of AP-1 proteins to DNA (3). These actions result in the inhibition of the transcriptional induction of AP-1 -dependent genes as COX-2 and VEGF (4). Some of these effects occur through alteration of the cellular redox state and can be reverted by precursors of GSH as NAC.
15d-PGJ2 interferes with AP-1 –dependent induction of COX-2 and VEGF transcription at several steps. 15d-PGJ2 reduces the activation/phosphorylation of JNK induced upon cell stimulation (1), what results in diminished activation and phosphorylation of c-Jun (2) reducing its transactivation activity. Besides, this cyclopentenone inhibits the binding of AP-1 proteins to DNA (3). These actions result in the inhibition of the transcriptional induction of AP-1 -dependent genes as COX-2 and VEGF (4). Some of these effects occur through alteration of the cellular redox state and can be reverted by precursors of GSH as NAC.