[R.B.]

Some of you may also have seen the vitamin D threads in the nutrition section that suggest those with 'higher' levels of vitamin D on average have a lower risk of BC / recurrence.

The body is enormously complicated and interlinked as is evidenced by the paper below. The study suggests there may be links between the vitamin D pathways and Omega 6 pathways. PGE2 (a prostaglandin) is an oxidised downstream product of the 20 carbon fat called arachidonic acid (a member of the Omega 6 family, its name is explained by the fact it was first isolated from a spider). PGE2 features in lots of body functions, including inflammation, and hormone production.

The paper suggests links between a combination of increased Omega 6 PGE2 and lower Vitamin D (calcitriol) in breast cancer patients - double trouble.

Another paper on vitamin D and cancer below suggests a mechanism. Vitamin D is suggested to regulate enzymes that produce and dispose of prostaglandins including one called COX2, which is the enzyme that allows PGE2 to be made.

As a very broad generalisation Omega 3 competes for the same enzymes as Omega 6, and those with lower Omega 6 tend to have lower levels of Omega 6 products including PGE2 in their systems. In this way increased Omega 3 and lower Omega 6 may reduce the risk of a number of conditions including an array of cancers including BC and prostate cancer

A significant number of non-steroidal drugs commonly block the production or action of PGE2, which may explain why they and asprin may be associated with a reduction in the risk of cancer - but have other side effects



"Prostaglandin Metabolising Enzymes and PGE2 are Inversely Correlated with Vitamin D Receptor and 25(OH)2D3 in Breast Cancer

http://ar.iiarjournals.org/content/30/5/1673.abstract

Abstract

Background: Breast cancer is associated with inflammatory processes based on an up-regulation of cyclooxygenase-2 (COX-2) expression. The antiproliferative effects of calcitriol (1,25(OH)2D3) mediated via the vitamin D receptor (VDR) render vitamin D a promising target in breast cancer therapy. First data suggest a correlation between vitamin D and prostaglandin metabolism. Materials and Methods: We determined the expression of VDR, COX-2, 15-PGDH and the prostaglandin receptors EP2/EP4 in normal and malignant breast tissue by real-time PCR and Western blot analysis, as well as 25(OH)2D3 and PGE2 plasma levels from healthy and breast cancer patients. Results: Significantly higher COX-2, lower VDR and lower EP2 and EP4 receptor protein levels in the malignant tissue and a significantly lower 15-PGDH protein level in normal breast tissue were detected. Breast cancer patients older than 45 years, diagnosed and sampled in the wintertime had significantly lower 25(OH)2D3 and higher PGE2 serum levels. Conclusion: The inverse correlation between VDR and both COX-2 and 15-PGDH, as well as between PGE2 and 25(OH)2D3 levels, suggests a possible link between VDR-associated target genes and prostaglandin metabolism."

Vitamin D and cancer: current dilemmas and future research needs1,2,3
Cindy D Davis
1 From the Nutritional Sciences Research Group, National Cancer Institute, Rockville, MD

2 Presented at the National Institutes of Health conference "Vitamin D and Health in the 21st Century: an Update," held in Bethesda, MD, September 5–6, 2007.


(the paper includes the following quote)

"Vitamin D regulates many genes involved in prostaglandin metabolism. 1,25(OH)2D inhibits COX-2 expression and activity, inhibits expression of prostaglandin receptors, and increases prostaglandin catabolism by increasing expression of 15-prostaglandin dehydrogenase (25). In combination, these 3 mechanisms reduce prostaglandin levels and signaling, thereby attenuating the growth-stimulatory effects of prostaglandins in prostate cancer (25). Furthermore, 1,25(OH)2D and naproxen (a nonsteroidal antiinflammatory drug) act synergistically in vitro and inhibit prostate cancer cell growth more effectively than either alone in patients on the basis of a slowing of the prostate-specific antigen doubling time (25). Thus, by understanding the molecular targets for vitamin D, researchers can develop more effective strategies for cancer prevention and treatment. "