Biomedical subjects

T Camilli

Publications and source records attributed to T Camilli.

5 recordsLinked to original sources

PubMed2001

[Arachidonic acid and prostaglandins, inflammation and oncology].

CYCLOOXYGENASE PATHWAY: Among the 3 metabolic pathways leading to oxidation of arachidonic acid, the cyclooxygenase (COX) pathway produces prostaglandin G2 that is rapidly transformed into prostaglandin H2. PROSTAGLANDINS: Prostaglandins are inflammation mediators that are strongly implicated in tumorgenesis. They participate in tumor initiation, promotion and growth. INFLAMMATION AND EPITHELIAL CANCER: Chronic inflammation is a risk factor for epithelial cancer. It induces prostaglandin synthesis via activation of COX-2. There is a cause and effect relationship between chronic inflammation and carcinogeneis via COX-2 expression. It has been demonstrated that COX-2 favors tumor invasion and inhibits apoptosis. Tumor growth is favored by PGE2-induced reduction in immunity; COX-2 inhibitors reinforce the immune response. Finally COX-2 is expressed in tumor neovessels and plays a role in angiogenesis.

Arachidonic Acid↗

PubMed2001

[Cyclooxygenases].

TWO ISOFORMS: There are two isoforms of cyclooxygenase (COX) with similar structure and metabolic activity. COX-1 is a constitutional enzyme. COX-2 is an inductible form. CYCLOOXYGENASE-1: COX-1 is present in most tissues, particularly in the kidney, the digestive tract mucosa, platelets, brain, liver and spleen. CYCLOOXYGENASE-2: COX-2 expression can be induced by an inflammatory process. Implicated in the development of certain cancers, COX-2 is expressed in numerous tumor cell lines and in most epithelial carcinomas. COX-2 favors tumor invasion and inhibits apoptosis. When it is absent, tumor growth is slower or stopped.

Apoptosis↗

PubMed2001

[Cyclooxygenase inhibitors].

DISTINCT EFFECTS: Since the discovery of the two isoforms of COX, the therapeutic effects of nonsteroidal antiinflammatory drugs (NSAID) can be distinguished from their adverse effects linked to the inhibition of the constitutional form via selective inhibition of the inducible form. Non-selective NSAID that inhibit both COX isoforms are difficult to use for long-term regimens. NSAID AND CANCER PREVENTION: Epidemiology studies and animal and in vitro studies have demonstrated that regular use of NSAID reduced the incidence of colorectal cancer and certain precancer lesions. PROMISING PERSPECTIVES: COX-2 specific inhibitors, for example cerecoxib or rofecoxib, are potentially interesting for human therapy for chemoprevention of epithelial cancer or as medical treatment, alone or in combination with other anticancer treatments.

Animals↗

PubMed2001

Effects of tobacco smoke and benzo[a]pyrene on human endothelial cell and monocyte stress responses.

Smoking is an important risk factor for atherosclerosis. We compared tobacco smoke filtrate with benzo[a]pyrene (a prominent xenobiotic component of tobacco smoke) for the capacity to induce stress proteins and cause cell death in human monocytes and vascular endothelial cells, two cell types that are involved in the formation of atherosclerotic lesions. Exposure to freshly prepared filtrates of tobacco smoke induced in both monocytes and endothelial cells expression of the inducible heat shock protein (HSP)70 and heme oxygenase-1 (HO-1) and produced loss of mitochondrial membrane potential. Later, cell death by apoptosis or necrosis occurred depending on the concentration of tobacco smoke. These toxic effects could be prevented by the antioxidant N-acetylcysteine. In contrast, exposure of these cells to benzo[a]pyrene alone evoked neither stress proteins nor mitochondrial damage but did induce cell death by necrosis. Thus our results indicate that tobacco smoke rapidly induces complex oxidant-mediated stress responses in both vascular endothelial cells and circulating monocytes that are independent of the benzo[a]pyrene content of the smoke.

Acetylcysteine↗

PubMed2000

Benzo[a]pyrene induces the transcription of cyclooxygenase-2 in vascular smooth muscle cells. Evidence for the involvement of extracellular signal-regulated kinase and NF-kappaB.

Polycyclic aromatic hydrocarbons, such as benzo[a]pyrene (B[a]P) present in tobacco smoke and tar, have been implicated in the development of atherosclerosis as well as cancer. Increased expression of cyclooxygenase-2 (COX-2) has been detected both in atherosclerotic lesions and in epithelial cancers. To determine whether polycyclic aromatic hydrocarbons might directly affect COX expression in vascular cells, we investigated the effects of B[a]P on COX-2 expression in human and rat arterial smooth muscle cells (SMC). Treatment with B[a]P increased levels of COX-2 protein and mRNA and enhanced prostaglandin synthesis. Nuclear runoff assays and transient transfections revealed increased COX-2 gene transcription after treatment with B[a]P. Experiments were done to define the signaling mechanism by which B[a]P induced COX-2. B[a]P caused a rapid increase in phosphorylation of extracellular signal-regulated kinase (ERK); pharmacologic inhibition of mitogen-activated protein kinase kinase blocked B[a]P-mediated induction of COX-2. Depletion of the intracellular antioxidant, glutathione, with buthionine sulfoximine significantly increased B[a]P-mediated induction of COX-2 while exposure to N-acetylcysteine, a precursor of glutathione, suppressed the induction of COX-2 by B[a]P. Several lines of evidence suggest that the induction of COX-2 by B[a]P is mediated, at least in part, by NF-kappaB. Treatment with B[a]P increased binding of NF-kappaB to DNA. Moreover, B[a]P-mediated stimulation of COX-2 promoter activity was blocked when a construct containing a mutagenized NF-kappaB site was used. Pharmacological inhibitors of NF-kappaB blocked the induction of COX-2 protein and the stimulation of COX-2 promoter activity by B[a]P. Taken together, these data are likely to be important for understanding the atherogenic effects of tobacco smoke.

Animals↗