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  • 1
    ISSN: 1573-7276
    Keywords: cAMP ; colon cancer ; DLD-1 ; phosphodiesterase ; rolipram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate mechanisms for regulation of intracellular cAMP involved in cancer cell invasion, phosphodiesterase (PDE) activity in a colon cancer cell line, DLD-1, was studied. Activities of PDE 2, 4, and 5 were detected in DLD-1 cells by pharmacological approach. Specific and cell permeable inhibitors for those PDEs were used to determine which PDE is responsible for cAMP turnover involved in cancer cell motility. Treatment of DLD-1 cells with rolipram and Ro-20-1724, inhibitors for PDE 4, elevated intracellular cAMP contents three to five times of control. EHNA, an inhibitor for PDE 2, and zaprinast, an inhibitor for PDE 5, did not affect cAMP levels. To assess cellular motility, we utilized chemotaxis assay. EHNA and zaprinast did not suppress serum-induced chemotaxis. In contrast, rolipram and Ro-20-1724, suppressed chemotaxis in a dose dependent fashion. These suggest that PDE 4 plays a critical role in regulating intracellular cAMP levels of colon cancer cells and is involved in cancer invasion. PDE 4 can be a novel target of anti-invasion drug.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7276
    Keywords: endothelial cell retraction ; focal adhesion kinase ; invasion ; tyrosine phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Although endothelial cell retraction is required before tumor cell invasion, its molecular mechanism still remains obscure. We previously demonstrated that conditioned medium (CM) derived from a human pan-creatic cancer cell line, PSN-1, induced endothelial cell retraction and facilitated tumor cell invasion. To investigate the molecular change of events in the transduction of extracellular signals during endothelial cell retraction, we examined the effect of the CM derived from PSN-1 cells on the tyrosine phosphorylation in endothelial cells. Immunoblot analyses revealed that the PSN-1 CM decreased tyrosine phosphorylation of a 120-130 kD protein, and induced the concomitant down-regulation of focal adhesion kinase, pp125FAK , dur-ing endothelial cell retraction in time- and dose-dependent fashions. These changes preceded endothelial cell retraction and were reversible after removal of the CM. Further quantitative densitometric analyses demon-strated that the extent of decrea se in tyrosine phosphorylated 120-130 kD protein during the endothelial cell retraction was likely to be proportional to that of the down-regulation of pp125FAK . A tyrosine phosphory-lated 120-130 kD protein immunoprecipitated by anti-phosphotyrosine antibody immunoreacted with anti-pp125FAK antibody. These results suggested that decreased amount of a tyrosine phosphorylated 120-130 kD protein probably due to the down-regulation of pp125FAK might be associated with the signal transduction pathway in the endothelial cells during their retraction. Furthermore, these findings were also observed in the CM from another four human cancer cell lines, suggesting the down-regulation of pp125FAK in endothelial cells during tumor cell invasion. © Rapid Science 1998
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-7276
    Keywords: cell surface blebbing ; invasion ; pseudopodia ; rac ; rho
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Lysophosphatidic acid (LPA) triggers the invasion of a mesothelial cell monolayer by rat ascites hepatoma (MM1) cells. LPA also induces rapid morphological changes of MM1 cells, cell surface blebbing and pseudopodia formation. Pseudopodia formation is tightly correlated with cellular invasiveness. Clostridium Botulinum C3 exoenzyme and genistein abrogated the formation of blebs and pseudopodia together with the inhibition of invasion, indicating that GTPase Rho and certain tyrosine kinases are involved in both processes. MM1 cells expressing constitutively active Rho exhibited the invasion and the formation of blebs and pseudopodia in the absence of LPA. In contrast, MM1 cells expressing constitutively active Rac were not invasive in the absence of LPA, but were invasive in the presence of LPA. Their morphological response to LPA was almost the same as that of parental MM1 cells. Expression of dominant negative Rac suppressed the invasiveness to approximately 3% of that of parental MM1 cells, together with the inhibition of pseudopodia formation. Thus, Rho and Rac are cooperatively involved in both the invasion and the related morphological changes of MM1 cells. Rho activation is sufficient both for the induction of invasion and the morphological changes leading to the invasion, whereas Rac activation is necessary but not sufficient by itself. We propose that Rho activation is not mediated by Rac but the cooperation of both GTPases is essential to trigger the invasive behavior of MM1 cells.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-7276
    Keywords: cell motility ; cilostazol ; colon cancer ; invasion ; phosphodiesterase type III
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Metastasis of cancer cells is initiated by the cellular migration into extracellular matrix and surrounding vessels. We previously showed that elevation of cAMP levels in cancer cells suppressed trans-cellular migration in vitro. Drugs that can elevate cAMP levels in cancer cells effectively may be applied to prevent metastasis in cancer patients. Cilostazol, an oral anti-platelet drug, is a specific cAMP phosphodiesterase type III inhibitor and has been clinically used to treat thrombosis patients. In chemotaxis assay, cellular migration of human colon cancer cells, DLD-1, was induced by 10 μg/ml of soluble fibronectin or 10% of fetal bovine serum (FBS). Treatment with cilostazol (50 μM) suppressed 92.3% or 84.6% of the migration in control cells, respectively. When DLD-1 cells were stimulated by soluble fibronectin in phagokinetic assay, migration assessed by the area of gold particle phagocytosis track was induced and cilostazol also decreased 67.3% of the cellular migration in control cells. Furthermore, in the trans-cellular migration assay, cilostazol suppressed cancer cell invasion induced by FBS. Thus, cilostazol can suppress colon cancer cell motility and might be effective as an anti-metastasis drug for cancer patients.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-7276
    Keywords: apigenin ; azoxymethane ; bombesin ; cancer metastasis ; intestinal cancer ; MMP-9 ; MAPK
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of a naturally occurring flavonoid apigenin on the development of bombesin-enhanced peritoneal metastasis from intestinal adenocarcinomas induced by azoxymethane was investigated in male Wistar rats. From the start of the experiment, rats were given weekly s.c. injections of azoxymethane (7.4 mg/kg body weight) for 10 weeks and s.c. injection of bombesin (40 μg/kg body weight) every other day, and from week 16, s.c. injections of apigenin (0.75 or 1.5 mg/kg body weight) every other day until the end of the experiment in week 45. Bombesin significantly increased the incidence of intestinal tumors and cancer metastasis to the peritoneum in week 45. It also significantly increased the labeling index of intestinal cancers. Although administration of apigenin at either dose with bombesin had little or no effect on the enhancement of intestinal carcinogenesis by bombesin, the location, histologic type, depth of involvement, infiltrating growth patterns and labeling index, it was found to decrease significantly the incidence of cancer metastasis. Apigenin significantly decreased the incidence of lymphatic vessel invasion of adenocarcinomas, which was enhanced by bombesin. In vitro experiments revealed that apigenin inhibited bombesin-enhanced phosphorylation of mitogen-activated protein kinase (MAPK), but not matrix metalloprotease (MMP)-9 expression. Our findings indicate that apigenin inhibits cancer metastasis through inhibition of phosphorylation of MAPK.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1534-4681
    Keywords: Invasion ; Metastasis ; Endothelial cell retraction ; Pancreatic cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Tumor cells induce endothelial cell retraction before invasion. In pancreatic cancer cells, the factors affecting endothelial cell retraction are not well-understood. Methods: The activities of the endothelial cell retraction in conditioned media (CM) derived from three human pancreatic cancer cell lines, PSN-1, MiaPaca-2, and Capan-1, were measured for the amount of intercellular junctional transport of FITC dextran through an endothelial cell monolayer in a transwell cell culture system. Results: The CM derived from the three pancreatic cancer cells induced endothelial cell retraction. The endothelial cell retraction activity in the CM from PSN-1 cells was significantly higher than those from MiaPaca-2 and Capan-1 cells. The CM from PSN-1 cells enhanced both the adhesion and the invasion of MiaPaca-2 and Capan-1 cells. The factors with endothelial cell retraction activity in the CM from PSN-1 cells were characterized as heat-stable, trypsin-sensitive glycoproteins ranging from 10,000 to 50,000 in molecular weight, and were found both in heparinbound and unbound fractions. Conclusions: PSN-1 cells produced and secreted at least two factors inducing the endothelial cell retraction. The factors could play an important role in the establishment of invasion and metastasis of PSN-1 cells.
    Type of Medium: Electronic Resource
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