epidermal-growth-factor and Ascites

Malignant ascites from pancreatic cancer patients has been reported to stimulate migration of pancreatic cancer cells through lysophosphatidic acid (LPA) and LPA(1) receptors. Indeed, ascites- and LPA-induced migration was inhibited by Ki16425, an LPA(1) and LPA(3) antagonist, in Panc-1 cells. Unexpectedly, however, in the presence of Ki16425, ascites and LPA inhibited cell migration in response to epidermal growth factor (EGF). The inhibitory migratory response to ascites and LPA was also observed in the cells treated with pertussis toxin (PTX), a G(i) protein inhibitor, and attenuated by a small interfering RNA (siRNA) specific to the LPA(2) receptor. The inhibitory LPA action was reversed by the regulators of G-protein signaling domain of p115RhoGEF, dominant-negative RhoA or C3 toxin. Indeed, LPA activated RhoA, which was attenuated by the siRNA against the LPA(2) receptor. Moreover, LP-105, an LPA(2) agonist, also inhibited EGF-induced migration in the PTX-treated cells. A similar inhibitory migration response through LPA(2) receptors was also observed in YAPC-PD, BxPC-3, CFPAC-1 and PK-1 pancreatic cancer cell lines. LPA also inhibited the invasion of Panc-1 cells in the PTX-treated cells in the in vitro Matrigel invasion assay. We conclude that LPA(2) receptors are coupled to the G(12/13) protein/Rho-signaling pathway, leading to the inhibition of EGF-induced migration and invasion of pancreatic cancer cells.

Topics: Ascites; Cell Line, Tumor; Cell Movement; Collagen; Drug Combinations; Epidermal Growth Factor; GTP-Binding Protein alpha Subunits, Gi-Go; Humans; Isoxazoles; Laminin; Lysophospholipids; Neoplasm Invasiveness; Pancreatic Neoplasms; Pertussis Toxin; Propionates; Proteoglycans; Receptors, Lysophosphatidic Acid; rhoA GTP-Binding Protein; RNA, Small Interfering

Cytokines and growth factors in malignant ascites are thought to modulate a variety of cellular activities of cancer cells and normal host cells. The motility of cancer cells is an especially important activity for invasion and metastasis. Here, we examined the components in ascites, which are responsible for cell motility, from patients and cancer cell-injected mice. Ascites remarkably stimulated the migration of pancreatic cancer cells. This response was inhibited or abolished by pertussis toxin, monoglyceride lipase, an enzyme hydrolyzing lysophosphatidic acid (LPA), and Ki16425 and VPC12249, antagonists for LPA receptors (LPA1 and LPA3), but not by an LPA3-selective antagonist. These agents also inhibited the response to LPA but not to the epidermal growth factor. In malignant ascites, LPA is present at a high level, which can explain the migration activity, and the fractionation study of ascites by lipid extraction and subsequent thin-layer chromatography indicated LPA as an active component. A significant level of LPA1 receptor mRNA is expressed in pancreatic cancer cells with high migration activity to ascites but not in cells with low migration activity. Small interfering RNA against LPA1 receptors specifically inhibited the receptor mRNA expression and abolished the migration response to ascites. These results suggest that LPA is a critical component of ascites for the motility of pancreatic cancer cells and LPA1 receptors may mediate this activity. LPA receptor antagonists including Ki16425 are potential therapeutic drugs against the migration and invasion of cancer cells.

Topics: Adult; Animals; Ascites; Blotting, Northern; Cell Adhesion; Cell Division; Cell Line, Tumor; Cell Movement; Chromatography, Thin Layer; Dose-Response Relationship, Drug; Epidermal Growth Factor; Female; Humans; Isoxazoles; Lipids; Lysophospholipids; Male; Mice; Mice, Inbred BALB C; Middle Aged; Monoacylglycerol Lipases; Neoplasm Invasiveness; Neoplasm Metastasis; Neoplasm Transplantation; Pancreatic Neoplasms; Pertussis Toxin; Propionates; Receptors, G-Protein-Coupled; Receptors, Lysophosphatidic Acid; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Transfection

Results are presented which show that mesothelial cells (MC) from ovarian cancer patients can both stimulate and inhibit the clonogenic growth of ovarian tumour cells (TC) in a dose-dependent fashion. TC lines from both non-ovarian and ovarian tumours were variable in their response to MC. Colony formation was rarely induced when the TC population was non-clonogenic and a bladder cell line showed inhibition of colony formation in the presence of MC. Primary tumour cultures from ovarian cancer patients also showed a variable response to MC. Fibroblasts from malignant, benign and non-neoplastic sources were significantly less effective in stimulating the clonogenic growth of responsive cell lines. Conditioned medium was a poor substitute for the presence of intact viable cells, and distance between feeder cell and TC was an important factor in determining the magnitude of response. A significant relationship between the feeder effect of MC and their proliferation in soft agar was observed when epidermal growth factor was used in the medium. The relevance of the findings in the context of the pattern of spread of ovarian cancer is discussed.

Topics: Ascites; Cell Communication; Cell Division; Epidermal Growth Factor; Epithelium; Female; Humans; Mesoderm; Ovarian Neoplasms; Tumor Cells, Cultured

Acid/ethanol extracts of normal rat liver and rat ascites hepatoma cells (AH 130) were found to inhibit the epidermal growth factor (EGF)-dependent colony formation of Balb/c 3T3 cells. The extracts did not inhibit the growth of the 3T3 cells in monolayer culture. The inhibitory activities were heat- and acid-stable and were not inactivated by the treatment with pronase, RNase and DNase. Upon ultrafiltration, a considerable fraction of the inhibitory activities were found in the fraction corresponding to the molecular size ranging from 3.5 to 10 Kd, in which no appreciable TGF-beta activity was detected.

Topics: Animals; Ascites; Cell Division; Cell Survival; Epidermal Growth Factor; Growth Inhibitors; Liver; Liver Neoplasms, Experimental; Mice; Peptides; Rats; Transforming Growth Factors