Reverse Transcription-PCR
Total RNA was extracted directly from RA (n = 16) and OA (n = 20) synovial tissues and evaluated by using the Agilent 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA, USA) as descried previously.[9] By using a random hexamer of oligonucleotides (Takara Bio Inc., Otsu, Japan), cDNAs were prepared from total RNA with SuperScript II reverse transcriptase (Life Technologies Inc., Rockville, MD, USA). The reaction product was subjected to reverse transcription (RT)-PCR analysis on the expression of ADAMs 8, 9, 10, 12, 15, 17, 20, 21, 28 and 30, VEGFR-1, VEGFR-2, neuropilin-1 and β-actin for 25–30 cycles. PCR was carried out in 50 μl reaction volume containing 800 nM of each primer, 220 μM of dNTPs and 1 unit of ExTaq DNA polymerase (Takara Bio Inc.). The thermal cycle was 1 minute at 94°C, 1 minute at 62°C for ADAMs 8, 9, 10, 12, 17, 20, 21, 28 and 30, 67°C for ADAM15, 64°C for VEGFR-1, 63°C for VEGFR-2 and neuropilin-1 and 65°C for β-actin, and 1 minute at 72°C, followed by 3 minutes at 72°C for the final extension. The nucleotide sequences of the PCR primers and the expected sizes of the amplified cDNA fragments are shown in Table 1 . Aliquots of the PCR products were electrophoresed in 2% agarose gels, and stained with ethidium bromide. For positive controls, total RNA was extracted from cancer cell lines as described previously.[9] The specific amplification of these ADAMs, VEGFRs, neuropilin-1 and β-actin was confirmed by direct sequencing of the PCR products.
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Protein Engineering
PCR
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ytochrome P450 (CYP) arachidonic acid epoxygenase 2J2 converts arachidonic acid to four regioisomeric epoxyeicosatrienoic acids, which exert diverse biological activities in cardiovascular system and endothelial cells. However, it is unknown whether this enzyme highly expresses and plays any role in cancer. In this study, we found that very strong and selective CYP2J2 expression was detected in human carcinoma tissues in 101 of 130 patients (77%) as well as eight human carcinoma cell lines but undetectable in adjacent normal tissues and nontumoric human cell lines by Western, reverse transcription-PCR, and immunohistochemical staining. In addition, forced overexpression of CYP2J2, and CYP BM3F87V or addition of epoxyeicosatrienoic acids (EET) in cultured carcinoma cell lines in vitro markedly accelerated proliferation by analyses of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell accounts, and cell cycle analysis, and protected carcinoma cells from apoptosis induced by tumor necrosis factor
(TNF-
) in cultures. In contrast, antisense 2J2 transfection or addition of epoxygenase inhibitors 17-ODYA inhibited proliferation and accelerated cell apoptosis induced by TNF-
. Examination of signaling pathways on the effects of CYP2J2 and EETs revealed activation of mitogen-activated protein kinases and PI3 kinase-AKT systems and elevation of epithelial growth factor receptor phosphorylation level. These results strongly suggest that CYP epoxygenase 2J2 plays a previously unknown role in promotion of the neoplastic cellular phenotype and in the pathogenesis of a variety of human cancers.
Advanced glycation end products (AGEs) are produced nonenzymatically by the Maillard reaction between amino acid (lysine and arginine) side chains in proteins and reducing sugars such as glucose (1). AGEs are found in the tissues of diabetic patients (2), and this accumulation has been implicated in the acceleration of diabetic microangiopathy, exemplified by retinopathy and nephropathy.
AGE-specific binding proteins were first identified in macrophages (OST-48 and the protein kinase C [PKC] substrate 80-KH) (3). In addition, two binding proteins for AGEs were identified on the surface of endothelial cells, receptor for AGEs (RAGE) and lactoferrin-like polypeptide (homologous to lactoferrin) (4). The interaction between AGEs and their receptors plays a key role in the progression of diabetic atherosclerosis and glomerulopathy (5,6).
AGEs have been shown to stimulate inducible nitric oxide (NO) synthase (iNOS) expression in endothelial cells (7), mouse macrophages (8), and RAW 264.7 cells (9,10). The high concentrations of NO produced by iNOS may play a role in the development of atherosclerosis (11). Interestingly, administration of exogenous NO donor agents causes inhibition of interferon (IFN)-{gamma} plus interleukin (IL)-1ß–induced iNOS expression in astroglial cells (12). Moreover, the inhibition of iNOS activity by N{omega}-methyl-L-arginine or N{omega}-nitro-L-arginine methyl ester
(L-NAME) augments lipopolysaccharide (LPS) plus IFN-{gamma}–induced iNOS expression in RAW 264.7 cells (13), suggesting that NO exerts a negative feedback effect.
Heme oxygenase (HO) is expressed in atherosclerotic lesions in both endothelial cells and foam cells (14). HO-1 is a stress-induced protein that is expressed in response to a variety of stimuli (15). HO-1 expression is implicated in protection against atherosclerosis. For example, mice deficient in both HO-1 and apolipoprotein (apo)E develop atherosclerosis more rapidly than mice deficient in apoE alone (16), and HO-1 overexpression inhibits atherosclerosis development in apoE-deficient mice (17). Furthermore, exogenous CO enhances the expression of the anti-inflammatory cytokine IL-10 through the p38 mitogen-activated protein kinase (MAPK) pathway (18). In addition, a recent study showed that HO-1 expression is upregulated in monocytes prepared from type 2 diabetic patients and is accompanied by the expression of the NADPH oxidase membrane component p22phox (19). Recently, AGEs also have been shown to stimulate HO-1 expression in endothelial cells (20).
HO-1 expression also appears to be involved in the regulation of iNOS expression. For example, HO-1 induction with heme or 15-deoxy-{Delta}12,14-prostaglandin J2 caused inhibition of iNOS expression.
These effects are proposed to be mediated by products of HO-1 because iNOS downregulation is diminished in the presence of Tin-protoporphyrin IX (Tin-PP) or zinc-protoporphyrin IX (21,22), both of which are inhibitors of HO-1.
Acetovanillone is a widely used NADPH oxidase inhibitor, which works by prevention of p47phox and p67phox membrane translocation, which is necessary for the activation of NADPH oxidase (23). The membrane translocation of the two components is regulated through the phosphorylation of cytosolic components through the p42/44 and p38 MAPKs and PKC (24–26). NADPH oxidase is activated by incubation with diabetic erythrocytes prepared from type 1 diabetic patients and with N{epsilon}-(carboxymethyl)lysine (27). AGEs activate NADPH oxidase, and this may lead to the production of reactive oxygen species, which can stimulate vascular cell adhesion molecule-1 expression (27) and inflammatory gene expression through nuclear factor-{kappa}B (NF-{kappa}B) activation (28).