Apoptosis induction and cyclooxygenase-2 regulation in human colorectal adenoma and carcinoma cell lines by the cyclooxygenase-2-selective non-steroidal anti-inflammatory drug NS-398

We determined the effect of the highly selective cyclooxygenase-2 (COX-2) inhibitor NS-398 on proliferation, apoptosis and COX-2 regulation in 3 pre-malignant human colorectal adenoma cell lines (RG/C2, AA/C1, RR/C1) and compared its effect on 3 colorectal carcinoma cell lines (HT29, KS, JW2). COX-2 protein was expressed in each cell line derived from an adenoma, thus providing evidence that COX-2 is expressed in the tumour cells themselves at an early stage in human colorectal adenoma formation. NS-398 (20 to 100 microM for 96 h) induced apoptosis and inhibited the proliferation of the adenoma cell lines. Of the 3 carcinoma lines, only HT29 expressed COX-2 protein, yet each line was similarly sensitive to NS-398. There was a positive correlation between overall sensitivity of the cell lines (determined by the attached cell yield) and sensitivity to NS-398-induced apoptosis, suggesting that apoptosis is the dominant anti-proliferative effect of NS-398. Two of the 3 adenoma cell lines (RG/C2, AA/C1) were less sensitive than the carcinoma cell lines. NS-398 up-regulated COX-2 protein expression in the HT29 and adenoma cell lines. This was studied further in HT29 cultures, where treatment with NS-398 inhibited COX-2 activity, reducing prostaglandin E(2) secretion. Here, neither the increase in COX-2 protein expression nor the anti-proliferative and apoptosis-inducing effect of NS-398 was prevented by addition of exogenous prostaglandin E(2). Apoptosis appears to be the dominant anti-proliferative effect of NS-398 and, in COX-2 expressing cells, may be mechanistically linked to the observed induction of COX-2 protein expression upon treatment with NS-398.

GNFFRFamide: a novel FMRFamide-immunoreactive peptide isolated from the sheep tapeworm, Moniezia expansa

The widespread distribution of FMRFamide-immunoreactivity in platyhelminth nervous systems has been demonstrated immunocytochemically. Here we report the isolation and primary structure of the first platyhelminth FMRFamide-related peptide (FaRP) from the tapeworm, Moniezia expansa. The peptide was found to have a molecular mass of 785 Da and a primary structure of Gly-Asn-Phe-Phe-Arg- Phe-NH2 (GNFFRFamide). Acid alcohol extracts of this platyhelminth contained only this single FaRP which had a phenylalanyl (F) residue in the variable position 3 from the C-terminal occupied by either methionyl (M), leucyl (L) or isoleucyl (I) residues in most other FaRPs.

Peptide tyrosine phenylalanine: a novel neuropeptide F-related nonapeptide from the brain of the squid, Loligo vulgaris

A novel nonapeptide, sequence YAIVARPRFamide, was isolated from brain extracts of the squid, L. vulgaris. Designated peptide tyrosine phenylalanine (PYF), the peptide shows marked homology with the C-terminal nonapeptides of pancreatic polypeptide and neuropeptide F (NPF) from a number of sources. If PYF is the C-terminal nonapeptide of squid NPF, then it may be derived by a novel processing mechanism involving specific cleavage between two TYR residues. PYF may be a highly truncated, receptor-active variant of NPF.

Apoptosis induction and cyclooxygenase-2 regulation in human colorectal adenoma and carcinoma cell lines by the cyclooxygenase-2-selective non-steroidal anti-inflammatory drug NS-398

We determined the effect of the highly selective cyclooxygenase-2 (COX-2) inhibitor NS-398 on proliferation, apoptosis and COX-2 regulation in 3 pre-malignant human colorectal adenoma cell lines (RG/C2, AA/C1, RR/C1) and compared its effect on 3 colorectal carcinoma cell lines (HT29, KS, JW2). COX-2 protein was expressed in each cell line derived from an adenoma, thus providing evidence that COX-2 is expressed in the tumour cells themselves at an early stage in human colorectal adenoma formation. NS-398 (20 to 100 microM for 96 h) induced apoptosis and inhibited the proliferation of the adenoma cell lines. Of the 3 carcinoma lines, only HT29 expressed COX-2 protein, yet each line was similarly sensitive to NS-398. There was a positive correlation between overall sensitivity of the cell lines (determined by the attached cell yield) and sensitivity to NS-398-induced apoptosis, suggesting that apoptosis is the dominant anti-proliferative effect of NS-398. Two of the 3 adenoma cell lines (RG/C2, AA/C1) were less sensitive than the carcinoma cell lines. NS-398 up-regulated COX-2 protein expression in the HT29 and adenoma cell lines. This was studied further in HT29 cultures, where treatment with NS-398 inhibited COX-2 activity, reducing prostaglandin E(2) secretion. Here, neither the increase in COX-2 protein expression nor the anti-proliferative and apoptosis-inducing effect of NS-398 was prevented by addition of exogenous prostaglandin E(2). Apoptosis appears to be the dominant anti-proliferative effect of NS-398 and, in COX-2 expressing cells, may be mechanistically linked to the observed induction of COX-2 protein expression upon treatment with NS-398.

Induction of apoptotic cell death in human colorectal carcinoma cell lines by a cyclooxygenase-2 (COX-2)-selective nonsteroidal anti-inflammatory drug: independence from COX-2 protein expression

Cyclooxygenase (COX) catalyzes the conversion of arachidonic acid to prostaglandin H2. The inducible isoform, COX-2, promotes colorectal tumorigenesis, and nonsteroidal anti-inflammatory drugs (NSAIDs) that selectively inhibit this isoform are chemopreventive in murine models of intestinal tumorigenesis. To establish a mechanism for their chemopreventive properties, we examined the effect of a COX-2-selective inhibitor, NS-398, on two colorectal carcinoma cell lines: HT29, which was found to express COX-2 protein constitutively; and S/KS, which did not express detectable levels of COX-2 protein. NS-398 had a dose-dependent antiproliferative effect on each cell line (IC50, 82.0 +/- 10.1 microM for HT29 and 78.6 +/- 11.1 microM for S/KS), and this was due to the induction of apoptosis. Cell cycle parameters were unaffected by NS-398 treatment. The ability of NS-398 to induce apoptosis provides a potential mechanism by which COX-2-selective inhibitors are chemopreventive and also indicates their potential as chemotherapeutic agents for colorectal cancer. That this effect was independent of COX-2 protein expression suggests that COX-2-selective NSAIDs may, like nonselective NSAIDs, be antineoplastic in the absence of COX-2.