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Biomedical subjects

Yuji Okada

Publications and source records attributed to Yuji Okada.

At least 19 recordsLinked to original sources
PubMed2006

Design and synthesis of rho kinase inhibitors (III).

The structure-activity relationship of Rho kinase inhibitors bearing an isoquinoline scaffold was studied. N-(1-Benzyl-3-pyrrolidyl)-N-(5-isoquinolyl)amine analogues were optimized with respect to their inhibitory potencies for the enzyme and for chemotaxis. The potent analogues were further evaluated by an ex vivo test in which the selected compounds were orally administered to rats, and the Rho kinase inhibitory potency observed in the rat serum was evaluated 3h after the administration. Compound 23g showed a high level of Rho kinase inhibitory activity in the rat serum and was stable in an in vitro metabolic test using a microsomal cytochrome preparation. The (R)-isomer of 23g displayed a higher level of inhibitory potency than the (S)-isomer in a cell-free kinase assay and in the cell migration assay (IC(50)(ENZ)=25 nM and IC(50)(MCP)=1 microM). The (R)-isomer successfully inhibited the phosphorylation of MBS (myosin-binding subunit) in cells.

Alkylation↗
PubMed2006

The stem cell factor/c-kit receptor pathway enhances proliferation and invasion of pancreatic cancer cells.

BACKGROUND: The transmembrane protein c-kit is a receptor tyrosine kinase (KIT) and KIT is expressed in solid tumors and hematological malignancies such as gastrointestinal stromal tumor (GIST), small-cell lung cancer and chronic myelogenous leukemia (CML). KIT plays a critical role in cell proliferation and differentiation and represents a logical therapeutic target in GIST and CML. In pancreatic cancer, c-kit expression has been observed by immunohistochemical techniques. In this study, we examined the influence of c-kit expression on proliferation and invasion using five pancreatic cancer cell lines. In addition, the inhibitory effect of imatinib mesylate on stem cell factor (SCF)-induced proliferation and invasion was evaluated. Finally, we also analyzed KIT and SCF expression in pancreatic cancer tissues using immunohistochemistry and correlated the results with clinical features. RESULTS: RT-PCR revealed that two pancreatic cancer cell lines, PANC-1 and SW1990, expressed c-kit mRNA. By Western blot analysis, c-kit protein was also present in those lines. In KIT-positive pancreatic cancer cell lines, proliferation and invasion were significantly enhanced by addition of SCF. In contrast, SCF did not enhance proliferation and invasion in the three KIT-negative lines (BxPC-3, Capan-2 and MIA PaCa-2). 5 muM imatinib mesylate significantly inhibited SCF-enhanced proliferation to the same extent compared with the control. Similarly, SCF-enhanced invasive ability was significantly inhibited by 5 muM imatinib mesylate. KIT was expressed in 16 of 42 clinical specimens by immunohistochemistry, and KIT expression was significantly related to venous system invasion. Furthermore, patients expressing both KIT and SCF had a somewhat lower survival. CONCLUSION: Our results demonstrated that the SCF-KIT pathway enhanced the proliferation and invasiveness in KIT-positive pancreatic cancer cell lines and that the enhanced proliferation and invasion were inhibited by imatinib mesylate. We propose that inhibitors of c-kit tyrosine kinase receptor have the potential to slow the progression of KIT-positive pancreatic cancers.

Aged↗
PubMed2006

Design and synthesis of Rho kinase inhibitors (II).

In a previous study, we identified several structurally unrelated scaffolds of the Rho kinase inhibitor using pharmacophore information obtained from the results of a high-throughput screening and structural information from a homology model of Rho kinase. 1H-Indazole is one of the candidate scaffolds on which a new series of potent Rho kinase inhibitors could be developed. In this study, the detailed structure-activity relationship of 1H-indazole analogues was studied. During this study, we found that the cell-free enzyme inhibitory potential of Rho kinase inhibitors having the 1H-indazole scaffold did not necessarily correlate with their inhibitory potential toward the chemotaxis of cultured cells. The choice of the linker substructure was shown to be an important factor for the 1H-indazole analogues to inhibit the chemotaxis of cells. Optimization of the 1H-indazole inhibitors with respect to the in vitro inhibition of monocyte chemotaxis induced by MCP-1 was carried out. The inhibitory potential was improved both in the cell-free enzyme assay and in the chemotaxis assay.

Binding Sites↗
PubMed2006

Malignant solitary fibrous tumor originating from the peritoneum and review of the literature.

BACKGROUND: Solitary fibrous tumor (SFT) is a rare neoplasm frequently involving the pleura. Benign and malignant forms of the tumor occur, the benign variant being three to four times more common than the malignant. CASE REPORT: We present herein a rare case of large malignant solitary fibrous tumor (SFT) originating from the peritoneum. An abdominal computed tomography scan revealed a well-defined solid tumor with mixed density. An abdominal ultrasonography (US) revealed a well-circumscribed solid tumor containing a partially cystic lesion. T1-weighted abdominal magnetic resonance imaging demonstrated a hypo- to isointensity, which was a hypo- to hyperintensity on T2-weighted images. Liposarcoma originating from the retroperitoneum was suggested, and the patient underwent a complete resection of the tumor as well as the left kidney because tumor invasion of the upper left kidney was suspected. Immunohistochemically, the spindle-shaped cells were positive for CD34, and the diagnosis was SFT originating from the peritoneum. At the 14-month follow-up evaluation, no recurrence or metastasis was detected. CONCLUSIONS: This case gave us some difficulty, and the correct diagnosis of the peritoneal mass was valuable. To diagnose the malignant potential of this type of tumor accurately may have value to direct the appropriate therapeutic operations after surgery and postoperative progress observation.

Adult↗
PubMed2006

Reactive lymphoid hyperplasia of the liver in a patient with colon cancer: report of two cases.

BACKGROUND: Reactive lymphoid hyperplasia (RLH) of the liver is very rarely reported, and we encountered two cases of RLH of the liver in a patient with colon cancer. CASE PRESENTATION: In the first case, a 77-year-old woman was admitted for the surgical removal of a ascending colon cancer. A hepatic tumor in the left lobe was concurrently revealed by computed tomography (CT), and magnetic resonance imaging (MRI). The appearance suggested liver metastasis. Right hemicolectomy and partial hepatectomy were performed. On histopathological examination, lymphoid follicles with germinal centers were seen in the tumor-like lesion, and remarkable lymphoid infiltration with germinal centers was seen in the portal area around the nodule. Immunohistochemical studies revealed polyclonality of infiltrating lymphocyte. Consequently, this nodular lesion was diagnosed as RLH of the liver. In the second case, a 64-year-old woman who had a radical right hemicolectomy for stage II ascending colon cancer 10 years ago was admitted with dysuria. A hepatic tumor in the left lobe was concurrently revealed by CT and MRI, suggesting hepatocellular carcinoma. A left lateral segmentectomy was performed. Microscopically, this lesion revealed the almost same findings as the first case, so this nodular lesion was diagnosed as RLH of the liver. CONCLUSION: Our two cases were the first report of RLH of the liver accompanying colon cancer. Because there are a very few cases, so it is not clear whether the malignancies were involved in the onset of RLH. But we believe that new factors involved in the onset mechanism of RLH may be identified by carefully monitoring the clinical course of our two patients.

Adenocarcinoma↗
PubMed2006

Outcomes in patients with interrupted aortic arch and associated anomalies: a 20-year experience.

OBJECTIVE: The surgical results for the repair of interrupted aortic arch (IAA) have evolved in recent years. We report our results for staged repair of this complex congenital malformation. METHODS: Sixty-five patients (mean age, 16.9+/-41.7 days) were diagnosed with IAA and referred for surgical therapy. The surgical management strategy at our institution between 1982 and 2005 has been one-stage complete repair (n=13) or staged repair (n=52) in selected patients. Non-complex patients (group I, n=51) had a ventricular septal defect (87%), aortopulmonary window (8%), and left ventricular outflow tract obstruction (27%). Group II (n=14) were patients with Taussig-Bing double outlet right ventricle (n=6) or truncus arteriosus (n=8). Method of staged repair of IAA was to transect and turn down the left carotid artery and anastomosis it to the descending aorta (n=41) or graft interposition (n=2) combined with a pulmonary artery (PA) banding followed in a few months by delayed ventricular septal defect (VSD) closure and PA de-banding. RESULTS: There were 5 early and 10 late deaths. The actuarial survival including early mortality was 92% at 1 year, 81% at 5 years, and 76% at 10 and 15 years. There was an 81% 15-year survival for children in group I compared with a 54% for children in group II (p<0.001). Risk factors for increased mortality by univariate analysis were as follows: (1) primary aortic anastomosis (p=0.03), (2) presence of complex anomalies (p=0.05), and (3) initial IAA repair performed before 1994 (p=0.05). Actuarial freedom from any type of aortic reoperation or intervention was 86% at 1 year, 69% at 5 years, and 60% at 10 and 15 years. Univariate and multivariate analyses identified no tested variables as risk factors for reoperation. The majority (86%) was in New York Heart Association (NYHA) class I, and 14% remained in NYHA class II. During the postoperative course there were no neurologic deficits, seizures, and growth disturbances in any patient. CONCLUSION: Staged repair of IAA using a left carotid artery turn down can be safely applied in IAA patients with and without other intracardiac anomalies with good results. Use of the left carotid artery for arch reconstruction did not result in any detectable neurological events or growth disturbances later in life. Associated anomalies played an important role in outcomes. The long-term probability for reoperation and/or reintervention remains high regardless of operative technique.

Aorta, Thoracic↗
PubMed2006

Interleukin-1alpha enhances the aggressive behavior of pancreatic cancer cells by regulating the alpha6beta1-integrin and urokinase plasminogen activator receptor expression.

BACKGROUND: In human pancreatic cancer progression, the alpha6beta1-integrin is expressed on cancer cell surface during invasion and metastasis formation. In this study, we investigated whether interleukin (IL)-1alpha induces the alterations of integrin subunits and urokinase plasminogen activator/urokinase plasminogen activator receptor (uPA/uPAR) expression in pancreatic cancer cells. We hypothesize that the alterations of integrin subunits and uPA/uPAR expression make an important role in signaling pathways responsible for biological behavior of pancreatic cancer cells. RESULTS: IL-1alpha upregulated the expression of alpha6 and beta1 integrins without any alterations of alpha5 and alphav integrins expression. IL-1alpha also induced enhancement in the expression of uPA/uPAR in pancreatic cancer cells. IL-1alpha enhanced the proliferation, adhesion, and migration in pancreatic cancer cells, and IL-1alpha-induced alterations of uPA/uPAR expression correlated with the increased the migration of pancreatic cancer cells. Upregulation of alpha6 integrin subunit and uPA/uPAR correlated with the activation of Ras and downstream extracellular signal-regulated kinase (ERK) pathways. IL-1alpha-induced activation of Ras and downstream ERK can be inhibited by using inhibitory antibodies against alpha6 and beta1 integrin and uPAR, consistent with the inhibition of proliferation, adhesion and migration of pancreatic cancer cells. Immunohistochemical analysis demonstrated a significant association between strong expressions of alpha6 integrin with uPAR in pancreatic cancer specimens. Furthermore, the strong expression of alpha6 integrin and uPAR was found to be independent prognosticator in pancreatic cancer patients. CONCLUSION: Based on these findings, we conclude that IL-1alpha can induce selective upregulation of alpha6beta1-integrin and uPA/uPAR in pancreatic cancer cells and these changes may modulate the aggressive functions of pancreatic cancer.

Aged↗
PubMed2006

Study of temperature-responsibility on the surfaces of a thermo-responsive polymer modified stationary phase.

We investigated a thermo-sensitive polymer, poly(N-isopropylacrylamide) (PNIPAAm), which is the basis of an HPLC stationary phase. We prepared a PNIPAAm terminally-modified surface. In this study, we investigated the effect of PNIPAAm on the surface of a stationary phase on separation based on changes of the retention time with the temperature step gradient. As the temperature changed the surface property of the stationary phase switched from hydrophilic to hydrophobic. The retention on the polymer-modified stationary phase remarkably changed upon changing the temperature. Using a column packed with PNIPAAm-modified silica, the separation of steroids was carried out by changing the temperature. With increasing temperature, an increased interaction between solutes and PNIPAAm-grafted surfaces of the stationary phases was observed. A temperature-dependent resolution of steroids was achieved using only water as a mobile phase. The PNIPAAm-modified surface of the stationary phase exhibited temperature-controlled hydrophilic-hydrophobic changes. The drastic and reversible surface hydrophilic-hydrophobic property alteration for PNIPAAm terminally-grafted surfaces should be due to rapid changes in the polymer hydration state around the polymer's transition temperature. A solvent gradient elution-like effect could be achieved with a single mobile phase by programmed temperature changes during chromatographic runs. This system should be highly useful to control the function and property of the stationary phase for HPLC only by changing the temperature with an aqueous solvent.

Acrylic Resins↗
PubMed2005

The G691S RET polymorphism increases glial cell line-derived neurotrophic factor-induced pancreatic cancer cell invasion by amplifying mitogen-activated protein kinase signaling.

Mutations of the RET proto-oncogene are responsible for several inherited human diseases and may function as genetic modifiers of the disease. However, the role of RET mutations in pancreatic cancer has not been studied. Expression of the glial cell line-derived neurotrophic factor (GDNF) receptors RET and GDNF family receptor alpha1 (GFRalpha1) in human pancreatic cancer cells was determined by Western blot, immunofluorescence, and flow cytometry. The effect of GDNF on cell proliferation and invasion was assessed. Small interfering RNA and antibodies were used to evaluate the involvement of RET. The G691S RET polymorphism was analyzed by sequencing and restriction analysis. The modifying effect of G691S RET on GDNF-induced invasion and mitogen-activated protein kinase (MAPK) signaling was evaluated. Transfection studies with wild-type and mutated RET determined the functional role of the G691S polymorphism. Pancreatic cancer specimens and matched tissues were analyzed for the presence of the G691S RET polymorphism. GDNF receptors were found on all cell lines. GDNF increased pancreatic cancer cell proliferation and invasion, which was mediated by RET. The effect of GDNF was more profound in cells with the G691S RET polymorphism (P < 0.01). G691S RET correlated with an enhanced activation of the downstream extracellular signal-regulated kinase pathway. Overexpression of G691S RET increased pancreatic cancer cell invasion. The G691S RET polymorphism was also detected in human pancreatic tumors and represented a somatic mutation in some patients. These findings indicate that the G691S RET single nucleotide polymorphism may directly correlate with the aggressive growth of pancreatic cancers and may function as a genetic modifier or even low-penetrance gene.

Adenocarcinoma↗
PubMed2005

Activation of focal adhesion kinase enhances the adhesion and invasion of pancreatic cancer cells via extracellular signal-regulated kinase-1/2 signaling pathway activation.

BACKGROUND: Interaction with integrin and focal adhesion kinase (FAK) regulates the cancer cell adhesion and invasion into extracellular matrix (ECM). In addition, phosphorylation of FAK correlates with the increase of cell motility and invasion. Adhesion and spreading of cancer cells on a variety of ECM proteins, including collagen type IV (Coll IV), leads to an increase in tyrosine phosphorylation and activation of FAK. In this study, we investigated the mechanism of activation of FAK and its downstream extracellular signal-regulated kinase (ERK)-1/2 signaling following stimulation by interleukin (IL)-1alpha and adhesion to ECM with subsequent enhancement of pancreatic cancer cell adhesion and invasion. RESULTS: In immunoblotting analysis, all three pancreatic cancer cell lines (AsPC-1, BxPC-3, and Capan-2) expressed the protein of FAK and beta1 integrin. Enhancement of FAK protein association with beta1 integrin when cells were plated on Coll IV was more increased by stimulation with IL-1alpha. Preincubation with anti-beta1 integrin antibody and FAK siRNA transfection inhibited the association of FAK with beta1 integrin of pancreatic cancer cells. FAK phosphorylation was observed by adhesion to Coll IV, furthermore, stronger FAK phosphorylation was observed by stimulation with IL-1alpha of pancreatic cancer cells adhered to Coll IV in time-dependent manner. Genistein, a tyrosine kinase inhibitor, markedly inhibited the FAK phosphorylation. IL-1alpha stimulation and Coll IV adhesion enhanced the activation of Ras, as evidenced by the increased Ras-GTP levels in pancreatic cancer cells. Activation of Ras correlated with the phosphorylation of ERK. While not statistical affecting the apoptosis of pancreatic cancer cells, IL-1alpha-induced adhesion and invasion on Coll IV were inhibited with FAK gene silencing by siRNA, beta1 integrin blocking, and inhibition of FAK phosphorylation. PD98059, a MEK inhibitor, also inhibited IL-1alpha-induced enhancement of adhesion and invasion in pancreatic cancer cells. CONCLUSION: Our results demonstrated that activation of FAK is involved with the aggressive capability in pancreatic cancer through Ras/ERK signaling pathway. Based on our results, we suggest that the modification of IL-1, FAK, and integrins functions might be a novel therapeutic approach to aggressive spread of pancreatic cancer.

Apoptosis↗
PubMed2005

Interleukin-1alpha enhances IL-8 secretion through p38 mitogen-activated protein kinase and reactive oxygen species signaling in human pancreatic cancer cells.

BACKGROUND: Interleukin (IL)-1alpha plays an important role in modulating the expression of various growth factors and angiogenic factors in tumor cells. In here, we investigated effect of IL-1alpha on IL-8 secretion in human pancreatic cancer cells and underlying signal transduction pathways. MATERIAL/METHODS: IL-8 expression and secretion by pancreatic cancer cells was measured by Western blot and enzyme-linked immunosorbent assay (ELISA), respectively. Activation of extracellular signal regulated kinases-1/2 (ERK-1/2), p38 mitogen-activated protein kinase (MAPK), c-jun aminoterminal kinase, Akt, and nuclear factor-kappaB (NF-kappaB) was determined by Western blot. Involvement of reactive oxygen species (ROS) were examined by measuring the H2O2. Activity of activator factor-1 (AP-1) and NF-kappaB was examined by electrophoretic mobility sift assay (EMSA). Proliferation of human umbilical vein endothelial cells (HUVECs) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide dye reduction method and cell count. RESULTS: IL-1alpha modulated IL-8 secretion and induced activation of ERK-1/2 and p38 MAPK. Specific inhibitors for MEK-1 and p38 MAPK suppressed IL-8 secretion. IL-1alpha also induced production of ROS. Exogenous H2O2 enhanced IL-8 secretion and N-acetyl cysteine (NAC) prevented IL-1alpha-induced ROS production and IL-8 secretion. EMSA confirmed that IL-1alpha increased DNA-binding activity of AP-1 and NF-kappaB. Inhibitors and ROS scavenger studies revealed that upstream signalings for AP-1 and NF-kappaB were MAPK and ROS, respectively. Conditioned media from pancreatic cancer cells pretreated with IL-1alpha remarkably stimulated in vitro HUVECs growth. CONCLUSIONS: These results suggest that MAPK/AP-1 and ROS/NF-kappaB signaling pathways are involved in IL-1alpha-induced IL-8 secretion and that these paracrine signaling pathways enhance endothelial cell proliferation.

Blotting, Western↗
PubMed2005

The role of glial cell line-derived neurotrophic factor (GDNF) and integrins for invasion and metastasis in human pancreatic cancer cells.

BACKGROUND AND OBJECTIVES: It is generally accepted that the malignancy of pancreatic cancer is dependent upon the extent of invasion as well as metastasis. However, the factors and mechanisms are incompletely understood. We investigated whether glial cell lined-derived neurotrophic factor (GDNF) enhances the invasive and adhesive behaviors of pancreatic cancer cells by altering of the expression of integrins. METHODS: The expression of the GDNF receptor in pancreatic cancer cell lines (SW1990 and Capan-2) was confirmed by RT-PCR. Then we determined the expression of integrin subunits and the alteration of their expression by GDNF using flow-cytometric analysis and a cellular enzyme-linked immunosorbent assay (CELISA). Adhesion and invasion assay were performed to investigate whether increased integrin expression affected the interaction between cancer cells and ECM proteins. RESULTS: The GDNF receptor subunits were expressed in pancreatic cancer cells. GDNF enhanced the expression of some of the integrin subunits and increased their adhesive and invasive abilities. The enhanced expression and associated increase in adhesive and invasive abilities were inhibited by blocking the GDNF receptor or the integrin beta1 subunit. CONCLUSION: The enhancement of integrin expression by GDNF signaling through the GDNF receptor strongly influences invasion and adhesion to ECM proteins by pancreatic cancer cells.

Cell Adhesion↗
PubMed2005

Augmented cardiac hypertrophy in response to pressure overload in mice lacking the prostaglandin I2 receptor.

BACKGROUND: In the heart, the expressions of several types of prostanoid receptors have been reported. However, their roles in cardiac hypertrophy in vivo remain unknown. We intended to clarify the roles of these receptors in pressure overload-induced cardiac hypertrophy using mice lacking each of their receptors. METHODS AND RESULTS: We used a model of pressure overload-induced cardiac hypertrophy produced by banding of the transverse aorta in female mice. In wild-type mice subjected to the banding, cardiac hypertrophy developed during the observation period of 8 weeks. In mice lacking the prostaglandin (PG) I2 receptor (IP(-/-)), however, cardiac hypertrophy and cardiomyocyte hypertrophy were significantly greater than in wild-type mice at 2 and 4 weeks but not at 8 weeks, whereas there was no such augmentation in mice lacking the prostanoid receptors other than IP. In addition, cardiac fibrosis observed in wild-type hearts was augmented in IP(-/-) hearts, which persisted for up to 8 weeks. In IP(-/-) hearts, the expression level of mRNA for atrial natriuretic peptide, a representative marker of cardiac hypertrophy, was significantly higher than in wild-type hearts. In vitro, cicaprost, an IP agonist, reduced platelet-derived growth factor-induced proliferation of wild-type noncardiomyocytes, although it could not inhibit cardiotrophin-1-induced hypertrophy of cardiomyocytes. Accordingly, cicaprost increased cAMP concentration efficiently in noncardiomyocytes. CONCLUSIONS: IP plays a suppressive role in the development of pressure overload-induced cardiac hypertrophy via the inhibition of both cardiomyocyte hypertrophy and cardiac fibrosis. Both effects have been suggested as originating from the action on noncardiomyocytes rather than cardiomyocytes.

Animals↗
PubMed2005

Thromboxane A2 and prostaglandin F2alpha mediate inflammatory tachycardia.

Systemic inflammation induces various adaptive responses including tachycardia. Although inflammation-associated tachycardia has been thought to result from increased sympathetic discharge caused by inflammatory signals of the immune system, definitive proof has been lacking. Prostanoids, including prostaglandin (PG) D(2), PGE(2), PGF(2alpha), PGI(2) and thromboxane (TX) A(2), exert their actions through specific receptors: DP, EP (EP(1), EP(2), EP(3), EP(4)), FP, IP and TP, respectively. Here we have examined the roles of prostanoids in inflammatory tachycardia using mice that lack each of these receptors individually. The TXA(2) analog I-BOP and PGF(2alpha) each increased the beating rate of the isolated atrium of wild-type mice in vitro through interaction with TP and FP receptors, respectively. The cytokine-induced increase in beating rate was markedly inhibited in atria from mice lacking either TP or FP receptors. The tachycardia induced in wild-type mice by injection of lipopolysaccharide (LPS) was greatly attenuated in TP-deficient or FP-deficient mice and was completely absent in mice lacking both TP and FP. The beta-blocker propranolol did not block the LPS-induced increase in heart rate in wild-type animals. Our results show that inflammatory tachycardia is caused by a direct action on the heart of TXA(2) and PGF(2alpha) formed under systemic inflammatory conditions.

Animals↗
PubMed2005

Analysis of herbicides in water using temperature-responsive chromatography and an aqueous mobile phase.

A simple and rapid method has been developed for herbicides in water using temperature-responsive liquid chromatography (LC) and a column packed with poly(N-isopropylacrylamide) (PNIPAAm), a polymer anchored on the stationary-phase surface of modified silica. PNIPAAm reversibly changes its hydrophilic/hydrophobic properties in water in response to temperature. The method was used to determine five sulfonylurea and three urea herbicides. Separation was achieved with a 10 mM ammonium acetate (pH 3.0) isocratic aqueous mobile phase, and by changing the column temperature. The analytes were extracted from water by off-line solid-phase extraction (SPE) with an N-vinyl-pyrrolidone polymer cartridge. The average recoveries of the eight herbicides from spiked pure water, tap water and river water were 70-130% with relative standard deviations (RSDs) of <10%. The limits of quantitation (LOQ) of the eight herbicides were between 1 and 4 microg l(-1).

Acrylic Resins↗
PubMed2005

Growth stimulation of COX-2-negative pancreatic cancer by a selective COX-2 inhibitor.

Cyclooxygenase 2 (COX-2) inhibitors are promising antiangiogenic agents in several preclinical models. The aim of the present study was to evaluate the effect of selective COX-2 inhibitors on vascular endothelial growth factor (VEGF) production in vitro and angiogenesis and growth of pancreatic cancer in vivo, focusing on putative differences between COX-2-negative and COX-2-positive tumors. VEGF production and angiogenesis in vitro were determined by ELISA and endothelial cell migration assay. To determine whether the effect of COX-2 inhibitors was mediated by peroxisome proliferator-activated receptor gamma (PPAR-gamma), we used a dominant-negative PPAR-gamma and a pharmacologic inhibitor. In vitro findings were validated in a pancreatic cancer animal model. Microvessel density was assessed by CD31 immunostaining. Intratumoral prostaglandin and VEGF levels were measured by mass spectroscopy and ELISA. Selective COX-2 inhibitors had a concentration-dependent effect on VEGF production in vitro. Higher concentrations increased VEGF levels and stimulated angiogenesis by activating PPAR-gamma. In vivo, nimesulide increased VEGF production by cancer cells in COX-2-positive and COX-2-negative pancreatic tumors. In COX-2-negative pancreatic cancer, this effect was associated with an increase in angiogenesis and growth. In COX-2-positive pancreatic cancer, the nimesulide-induced increase of VEGF production by the cancer cells was offset by a decrease in VEGF production by the nonmalignant cell types leading to reduced tumor angiogenesis and growth. Selective COX-2 inhibitors had opposite effects on growth and angiogenesis in pancreatic cancer depending on COX-2 expression. These findings imply that assessing the COX-2 profile of the pancreatic tumor is mandatory before initiating therapy with a selective COX-2 inhibitor.

Animals↗