Cyclooxygenase-2 (COX-2), a rate-limiting enzyme in arachidonic acid cascade, plays a key role in the biosynthesis of prostaglandin E(2) (PGE(2)) upon inflammatory insults. Overproduction of PGE(2) stimulates proliferation of various cancer cells, confers resistance to apoptosis of cancerous or transformed cells, and accelerates metastasis and angiogenesis. Excess PGE(2) undergoes metabolic inactivation which is catalyzed by NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH). In this context, 15-PGDH has been speculated as a physiological antagonist of COX-2 and a tumor suppressor. Thus, overexpression of 15-PGDH has been known to protect against experimentally induced carcinogenesis and renders the cancerous or transformed cells susceptible to apoptosis by counteracting oncogenic action of PGE(2). In contrast, silence of 15-PGDH is observed in some cancer cells, which is associated with epigenetic modification, such as DNA methylation and histone deacetylation, in the promoter region of 15-PGDH. A variety of compounds capable of inducing the expression of 15-PGDH have been reported, which include the histone deacetylase inhibitors, nonsteroidal anti-inflammatory drugs, and peroxisome proliferator-activated receptor-gamma agonists. Therefore, 15-PGDH may be considered as a novel molecular target for cancer chemoprevention and therapy. This review highlights the role of 15-PGDH in carcinogenesis and its regulation.
"In tumors the steady-state level of PGE 2 is maintained by the biosynthetic pathway including both types of PGES, mPGES and cPGES and the catabolic pathways involving 15-PGDH. 15-PGDH is a crucial enzyme responsible for the biological inactivation of PGE 2 which induces cell proliferation, migration, angiogenesis and tumor metastasis (Na et al., 2011). 15-PGDH metabolizes PGE 2 by oxidizing the 15(S)-hydroxyl group into a keto group producing 15-keto PGE 2 (Tai et al., 2006). "
[Show abstract][Hide abstract] ABSTRACT: Cyclooxygenase-2 (COX-2), a rate limiting step in arachidonic acid cascade, plays a key role in the biosynthesis of prostaglandin E2 (PGE2) upon inflammatory stimuli, growth factors, hormones and other cellular stresses. Overproduction of PGE2 stimulates proliferation of various cancer cells, confers resistance to apoptosis and favors metastasis and angiogenesis. The steady-state level of PGE2 is maintained by interplay between the biosynthetic pathway including COX and PGE2 synthases and the catabolic pathways involving nicotinamide adenine dinucleotide (NAD(+))-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH). 15-PGDH is a crucial enzyme responsible for the biological inactivation of PGE2. Adult hepatocytes fail to induce COX-2 expression regardless of the pro-inflammatory factors used. COX-2 is induced in hepatocytes after partial hepatectomy (PH), in animal models of cirrhosis, in human hepatoma cell lines, in human HCC and after HBV and HCV infection. However, no data are available regarding 15-PGDH expression in HCC. Our results show that 15-PGDH is downregulated in human hepatoma cells with a high COX-2 expression, in chemical and genetic murine models of HCC and in human HCC biopsies. Moreover, 15-PGDH expression is suppressed by EGF (epidermal growth factor) and HGF (hepatocyte growth factor) mainly involving PI3K (phosphatidylinositol-3-kinase), ERK (extracellular signal-regulated kinase) and p38MAPK (mitogen-activated protein kinase) activation. Conversely, ectopic expression of 15-PGDH induces apoptosis in hepatoma cells and decreases the growth of hepatoma cells in nude mice whereas the silencing of 15-PGDH increases the tumor formation. These data suggest a potential therapeutic application of 15-PGDH in HCC.
The international journal of biochemistry & cell biology 08/2013; 45(11). DOI:10.1016/j.biocel.2013.08.005 · 4.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Prostanoids regulate angiogenesis in carcinoma and chronic inflammatory disease progression. Although prostanoid biosynthetic enzymes and signaling have been extensively analyzed in inflammation, little is known about how prostanoids mediate tumor-induced angiogenesis. Targeted cyclooxygenase (COX)-2 inhibition in tumor, stromal and endothelial cells is an attractive antiangiogenic strategy; however, the associated cardiovascular side effects have led to the development of a new generation of nonsteroidal anti-inflammatory drugs (NSAIDs) acting downstream of COX. These agents target terminal prostanoid synthases and prostanoid receptors, which may also include several peroxisome proliferator-activated receptors (PPARs). Here, we discuss the role of prostanoids as modulators of tumor angiogenesis and how prostanoid metabolism reflects complex cell-cell crosstalk that determines tumor growth. Finally, we discuss the potential of new NSAIDs for the treatment of angiogenesis-dependent tumor development.
Trends in Molecular Medicine 03/2012; 18(4):233-43. DOI:10.1016/j.molmed.2012.02.002 · 9.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Inflammation is a major cause of cancer and may condition its progression. The deregulation of the cyclooxygenase (COX) pathway is implicated in several pathophysiological processes, including inflammation and cancer. Although, its targeting with nonsteroidal antiinflammatory drugs (NSAIDs) and COX-2 selective inhibitors has been investigated for years with promising results at both preventive and therapeutic levels, undesirable side effects and the limited understanding of the regulation and functionalities of the COX pathway compromise a more extensive application of these drugs. Epigenetics is bringing additional levels of complexity to the understanding of basic biological and pathological processes. The deregulation of signaling and biosynthetic pathways by epigenetic mechanisms may account for new molecular targets in cancer therapeutics. Genes of the COX pathway are seldom mutated in neoplastic cells, but a large proportion of them show aberrant expression in different types of cancer. A growing body of evidence indicates that epigenetic alterations play a critical role in the deregulation of the genes of the COX pathway. This review summarizes the current knowledge on the contribution of epigenetic processes to the deregulation of the COX pathway in cancer, getting insights into how these alterations may be relevant for the clinical management of patients.
Progress in lipid research 05/2012; 51(4):301-13. DOI:10.1016/j.plipres.2012.02.005 · 10.02 Impact Factor
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