Abstract
We have investigated the possible functional relationships between cellular invasion pathways induced by trefoil factors (TFFs), src, and the cyclooxygenases COX-1 and COX-2. Pharmacological inhibitors of the Rho small GTPase (C3 exoenzyme), phospholipase C (U-73122), cyclooxygenases (SC-560, NS-398), and the thromboxane A2 receptor (TXA2-R) antagonist SQ-295 completely abolished invasion induced by intestinal trefoil factor, pS2, and src in kidney and colonic epithelial cells MDCKts.src and PCmsrc. In contrast, invasion was induced by the TXA2-R mimetic U-46619, constitutively activated forms of the heterotrimeric G-proteins Galphaq (AGalphaq), Galpha12, Galpha13 (AGalpha12/13), which are signaling elements downstream of TXA2-R. Ectopic overexpression of pS2 cDNA and protein in MDCKts.src-pS2 cells and human colorectal cancer cells HCT8/S11-pS2 initiate distinct invasion signals that are Rho independent and COX and TXA2-R dependent. We detected a marked induction of COX-2 protein and accumulation of the stable PGH2/TXA2 metabolite TXB2 in the conditioned medium from cells transformed by src. This led to activation of the TXA2-R-dependent invasion pathway, which is monitored via a Rho- and Galpha12/Galpha13-independent mechanism using the Galphaq/PKC signaling cascade. These findings identify a new intracrine/paracrine loop that can be monitored by TFFs and src in inflammatory diseases and progression of colorectal cancers.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Line, Transformed
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Cells, Cultured
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Culture Media, Conditioned
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Cyclooxygenase 1
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Cyclooxygenase 2
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DNA, Complementary / genetics
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DNA-Binding Proteins / metabolism
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GTP Phosphohydrolases / metabolism
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GTP-Binding Protein alpha Subunits, G12-G13
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GTP-Binding Protein alpha Subunits, Gq-G11
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Growth Substances / pharmacology*
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Heterotrimeric GTP-Binding Proteins / metabolism
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Humans
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Intestinal Mucosa / cytology
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Intestinal Mucosa / enzymology
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Isoenzymes / metabolism
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Kidney / cytology
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Kidney / enzymology
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Membrane Proteins
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Mucins*
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Muscle Proteins*
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Neoplasm Invasiveness
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Neuropeptides*
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Peptides / pharmacology*
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Prostaglandin-Endoperoxide Synthases / metabolism*
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Proteins / genetics
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Proteins / pharmacology
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Proto-Oncogene Proteins pp60(c-src) / pharmacology*
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Receptors, Thromboxane / metabolism*
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Signal Transduction
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Transfection
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Trefoil Factor-1
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Trefoil Factor-2
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Trefoil Factor-3
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Tumor Cells, Cultured
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Tumor Suppressor Proteins
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Type C Phospholipases / metabolism
Substances
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Culture Media, Conditioned
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DNA, Complementary
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DNA-Binding Proteins
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Growth Substances
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Isoenzymes
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Membrane Proteins
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Mucins
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Muscle Proteins
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Neuropeptides
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Peptides
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Proteins
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Receptors, Thromboxane
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TFF1 protein, human
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TFF3 protein, rat
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Trefoil Factor-1
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Trefoil Factor-2
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Trefoil Factor-3
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Tumor Suppressor Proteins
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Cyclooxygenase 1
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Cyclooxygenase 2
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PTGS1 protein, human
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PTGS2 protein, human
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Prostaglandin-Endoperoxide Synthases
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Proto-Oncogene Proteins pp60(c-src)
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Type C Phospholipases
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GTP Phosphohydrolases
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GTP-Binding Protein alpha Subunits, G12-G13
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GTP-Binding Protein alpha Subunits, Gq-G11
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Heterotrimeric GTP-Binding Proteins