Higher baseline expression of the PTGS2 gene and greater decreases in total colonic fatty acid content predict greater decreases in colonic prostaglandin-E2 concentrations after dietary supplementation with ω-3 fatty acids

Interactions of Colorectal Cancer, Dietary Fats, and Polymorphisms of Arachidonate Lipoxygenase and Cyclooxygenase Genes: A Literature Review

Objective

Genetics and dietary factors play important roles in the development of colorectal cancer (CRC). However, the underlying mechanisms of the interactions between CRC, gene polymorphisms, and dietary fat are unclear. This review study investigated the effects of polymorphisms of arachidonate lipoxygenase (ALOX) and cyclooxygenase (COX) genes in the association between CRC and dietary fat.

Methods

All the related papers published from 2000 to 2022 were collected from different databases such as PubMed, Science Direct, Scopus, and Cochran using related keywords such as colorectal cancer, ALOX, COX, polymorphism, and dietary fat. Non-English and unrelated documents were excluded.

Results

Some single-nucleotide polymorphisms (SNPs) in the ALOX and COX genes, such as rs2228065, rs6413416, and rs4986832 in the ALOX gene, and rs689465 in the COX gene may play significant roles in the association between the risk of CRC and dietary fats. SNPs of ALOX and COX genes may influence the effects of dietary fatty acids on the risk of CRC.

Conclusion

Some polymorphisms of the ALOX and COX genes may have important roles in the effects of dietary fat on the risk of CRC. If future studies confirm these results, dietary recommendations for preventing colorectal cancer may be personalized based on the genotype of the ALOX and COX genes.

The Importance of Drug Concentration at the Site of Action: Celecoxib and Colon Polyp Prevention as a Case Study

Celecoxib is among the more potent and better clinically studied, nonsteroidal anti-inflammatory drugs (NSAID) for use as a chemoprevention agent for colorectal cancer. Its use is associated with a 40% to 50% response rate for reduction in adenomatous polyps. However, rare serious cardiovascular effects and even death with celecoxib and other NSAIDs make it important to understand why some patients respond and others do not. Celecoxib is a selective inhibitor of COX-2. Its anticancer mechanism has largely been attributed to the inhibition of COX-2. Celecoxib also shows activity to induce apoptosis in cancer cells not expressing COX-2. This includes activity to upregulate 15-lipoxygenase-1 (15-LOX-1) independent of COX-2 and increase the synthesis of 13-S-hydroxyoctadecadienoic acid (13-S-HODE) from linoleic acid (LA) to downregulate PPAR-δ and induce apoptosis in colorectal cancer models. In examining the effect of celecoxib on 15-LOX-1 for reducing adenomatous polyps in patients with familial adenomatous polyposis (FAP), Yang and colleagues point out the potential importance of drug bioavailability in blood, normal, and neoplastic colorectal tissue in patient response. See related article, p. 217.

Changes in Serum, Red Blood Cell, and Colonic Fatty Acids in a Personalized Omega-3 Fatty Acid Supplementation Trial

This study evaluated changes in fatty acids from sera, red blood cells, and colonic biopsies from a phase Ib clinical trial of personalized ω-3 fatty acid dosing in 47 healthy volunteers. The trial aimed to reduce colonic prostaglandin E₂ (PGE₂), a pro-inflammatory product of arachidonic acid (AA) oxidation. The personalized doses ranged 2-10 grams/day (54% eicosapentaenoic acid, EPA, 24% other ω-3 fatty acids). In colon, increases in ω-3 highly unsaturated fatty acids (HUFA) and EPA:AA ratios each were correlated with decreases in PGE₂. Changes in either colonic EPA:AA ratios or ω-3 HUFA were significantly correlated with changes in the same fatty acid measures in red blood cells or serum. The only blood-based measure significantly correlated with changes in colonic PGE₂ was change in red blood cell ω-3 HUFA (ρ = -0.39), and the increase in red blood cell ω-3 HUFA was significantly greater in participants who had at least a median reduction in colonic PGE₂ vs. those who did not. In summary, fatty acid changes in blood did reflect fatty acid changes in the colon, but additional factors will be needed for optimizing dosing models that seek to predict the anti-inflammatory effects of ω-3 fatty acids on the colon.