[u:ca551d6a2c][b:ca551d6a2c]Life Extension Update - Health Concern [/b:ca551d6a2c][/u:ca551d6a2c]
Eicosanoids are hormones that are made within the cell membrane of each and every cell--all 60 trillion cells in the human body. Eicosanoids are 20-carbon structures. Eicosanoids have autocrine, paracrine, and endocrine effects. That is, they affect the very cell that produces the eicosanoid (autocrine effect), as well as nearby cells (paracrine effect) and distant cells (endocrine effect). As with every aspect of biology, balance is a critical issue relating to good health as well as the development and progression of various diseases. Likewise, eicosanoid balance plays a central role that puts this desired biological endpoint at the hub of the integrative medicine wheel. Eicosanoids, and the balance of good versus bad eicosanoids, can be seen as the heart and soul, muscle, bone, and sinew, literally and figuratively, of holistic medicine.
Clearly pertinent to a discussion of prostate cancer (PC) is the fact that the first eicosanoids isolated in 1936 by Ulf von Euler were prostaglandins--eicosanoids isolated from the prostate gland. Eicosanoids are the oldest hormones, tracing their origin back 500 million years ago to production by sponges. Hormones are messengers involved in communication between cells. A hormone is formally defined as a substance, usually a peptide or steroid, produced by one tissue and conveyed by the bloodstream to another to affect physiological activity, such as growth or metabolism.
Eicosanoid synthesis involves the release of arachidonic acid (AA) from cell membrane phospholipids by an enzyme called phospholipase A2 (PLA2). AA then undergoes metabolism by cyclooxygenases (COXs) and lipoxygenases (LOXs). AA is an omega-6 fatty acid that is known to generate free radicals and is considered an unfavorable eicosanoid. Specific metabolites of AA, for example, PGE2 and 5-HETE, are created through the actions of the enzymes COX-2, 5-LOX, 12-LOX, and 15-LOX. These metabolites are examples of bad eicosanoids and have been implicated in PC growth and metastasis. In a study of human PC in which 5-LOX and its metabolite 5-HETE were evaluated in both malignant and benign prostate tissue within the same patient, both 5-LOX and 5-HETE were significantly overexpressed in the PC tissue. In other words, specific eicosanoids are modulators of tumor cell interactions with certain host components within the context of cancer growth, invasion, and spread.
EPA, an omega-3 fatty acid, has been shown to suppress AA formation by inhibiting the enzyme delta-5-desaturase. Some epidemiologic studies have shown that high intakes of EPA and DHA lower PC risk substantially. Other studies have shown a reduction in PC risk only with a decrease in the ratio of AA to EPA (AA:EPA). A combination of GLA and EPA administered to humans was shown to strongly increase serum EPA and DGLA levels and to reduce AA formation and AA metabolites such as leukotrienes.