In the present study, 12-O-tetradecanoylphorbol-13-acetate (TPA) addition significantly inhibited GOS-induced apoptosis in human colorectal carcinoma HT-29 cells in accordance with inducing COX-2 protein/PGE(2) production.
Immunohistochemical profiling of colorectal cancer seems to be a promising approach, not only to define prognostic impact, but also to detail proliferation-related molecular interplays between EGFr and Cox-2 pathways, with these two latter proteins, at present, being the hottest pharmacological targets for colorectal cancer (CRC) chemoprevention and therapy.
However, prolonged use of COX-2 selective inhibitors (coxibs) increases cardiovascular toxicity in some individuals, which highlights the importance of identifying all of the molecular targets that drive progression of colorectal cancer.
To further elucidate the mechanism responsible for increased levels of PGE(2) in colorectal tumors, we determined the amounts of mPGES and COX-2 in 18 paired samples (tumor and adjacent normal) of colorectal cancer.
In the present study, we show that tumour promoter PMA-mediated induction of genes that are significantly associated with inflammation, tumour growth and metastasis, such as COX-2 (cyclo-oxygenase 2) and VEGF (vascular endothelial growth factor), is inhibited by PPARalpha ligands in the human colorectal carcinoma cell line SW620.
COX-2 inhibitors exhibit important anticarcinogenic potential against CRC, but the molecular mechanism underlying this effect and the relation with RTK signaling remain the subject of intense research effort.
Regular administration of non-steroidal anti-inflammatory drugs (NSAIDs) may reduce the incidence of colorectal cancer by targeting cyclo-oxygenase-2 (Cox-2), a key enzyme in arachidonic acid metabolism.
On the other hand, NPX and other NSAIDs are extensively studied in terms of colorectal cancer (CRC) prevention and inhibition, since it has been evidenced that COX-2 corresponds with the risk of the tumor occurrence and growth.
Since COX-2 inhibitors have been demonstrated to interfere with tumorigenesis and apoptosis, COX-2 and its gene product may be attractive targets for therapeutic and chemoprotective strategies in colorectal cancer patients.
Because both COX-2- and β-catenin-mediated transcription are important contributors to colorectal cancer (CRC) disease maintenance and progression, these findings suggest a unique and novel regulatory role for MIF family members in CRC pathogenesis.
However, increased gastrointestinal side effects of NSAIDs and increased cardiovascular risks of selective COX-2 inhibitors limit their use in chemoprevention of CRC.
We conclude that (1) the CRC and its margin contain large amounts of progastrin and show gene expression of gastrin, CCK(B)-R, and COX-2; (2) removal of the CRC markedly reduces the plasma concentrations of progastrin; (3) the Hp infection rate is higher in CRC, and this may contribute to colorectal cancerogenesis via enhancement of progastrin and gastrin release; and (4) plasma progastrin concentrations might serve as a biomarker of CRC.
Increased synthesis of PGE<sub>2</sub> in CRC has been shown to occur through COX-2-dependent mechanisms; however, loss of the PGE<sub>2</sub>-catabolizing enzyme, 15-hydroxyprostaglandin dehydrogenase (15-PGDH, HPGD), in colonic tumors contributes to increased prostaglandin levels and poor patient survival.
Here we showed that the addition of the COX-2 inhibitor celecoxib improved the antitumor efficacy in colorectal cancer (CRC) of the monoclonal anti-EGFR antibody cetuximab.
Combined analysis of COX-2 and p53 expressions reveals synergistic inverse correlations with microsatellite instability and CpG island methylator phenotype in colorectal cancer.
The CRC protective effects of apiaceous vegetables are mainly due to the inhibitory effect of FaOH and FaDOH on NF-κB and its downstream inflammatory markers, especially COX-2.
Therefore, the present study was designed to assess the prophylactic potentials of probiotics (Lactobacillus acidophilus and Lactobacillus rhamnosus GG) in conjunction with celecoxib, a selective cox-2 inhibitor in 1,2 dimethylhydrazine dihydrochloride (DMH)-induced experimental colon carcinogenesis, a well-established, well appreciated and widely used model for colorectal cancer that shares many similarities to human sporadic colorectal cancer with respect to response to some promotional and preventive agents.
These results show the necessity to perform succeeding studies, which could describe possible mechanisms in which gastrin and COX-2 contribute to the induction of colorectal carcinomas.
These data indicate that PGDH may serve a tumor suppressor function in colorectal cancer and provide a possible COX-2-independent way to target PGE(2) to inhibit cancer progression.
In conclusion, our study provided the evidence towards better antiproliferative effect of AR13 and AR15 in DMH-induced CRC through the blockade of COX-2/JAK-2/STAT-3 signal transduction pathway and could be demonstrated as useful anti-CRC candidate molecules for future anticancer therapy.