calcitriol(Vitamin D)not only synergistic w AI,but anti-prostaglandin,bone-conserving

Lani · 11-13-2009, 09:18 AM

I previously provided a link to one of Dr. Feldman's lectures on vitamin D

Endocrinology. 2009 Nov 11. [Epub ahead of print]
Tissue-Selective Regulation of Aromatase Expression by Calcitriol: Implications for Breast Cancer Therapy.
Krishnan AV, Swami S, Peng L, Wang J, Moreno J, Feldman D.

Departments of Medicine, Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305.
Aromatase, the enzyme that catalyzes estrogen synthesis, is critical for the progression of estrogen receptor-positive breast cancer (BCa) in postmenopausal women. We show that calcitriol, the hormonally active form of vitamin D, regulates the expression of aromatase in a tissue-selective manner. Calcitriol significantly decreased aromatase expression in human BCa cells and adipocytes and caused substantial increases in human osteosarcoma cells (a bone cell model exhibiting osteoblast phenotype in culture) and modest increases in ovarian cancer cells. Calcitriol administration to immunocompromised mice bearing human BCa xenografts decreased aromatase mRNA levels in the tumors and the surrounding mammary adipose tissue but did not alter ovarian aromatase expression. In BCa cells, calcitriol also reduced the levels of prostaglandins (PGs), major stimulators of aromatase transcription, by suppressing the expression of cyclooxygenase-2 (which catalyzes PG synthesis) and increasing that of 15-hydroxyprostaglandin dehydrogenase (which catalyzes PG degradation). The mechanism of aromatase down-regulation by calcitriol in BCa cells is therefore 2-fold: a direct repression of aromatase transcription via promoter II through the vitamin D-response elements identified in this promoter and an indirect suppression by reducing the levels of PGs. Combinations of calcitriol with three different aromatase inhibitors (AIs) caused enhanced inhibition of BCa cell growth. The combination of calcitriol and an AI may have potential benefits for BCa therapy. In addition to augmenting the ability of AIs to inhibit BCa growth, calcitriol acting as a selective aromatase modulator that increases aromatase expression in bone would reduce the estrogen deprivation in bone caused by the AIs, thus ameliorating the AI-induced side effect of osteoporosis.

PMID: 19906814

Rich66 · 11-13-2009, 09:34 AM

Can't find the Feldman link

Lani · 11-13-2009, 09:45 AM

http://med.stanford.edu/medcast/2008/vitamind.html

Rich66 · 11-13-2009, 10:44 AM

Thanks. Stacking up the D over here: http://her2support.org/vbulletin/showthread.php?t=41852

suzan w · 11-20-2009, 05:59 PM

hmmm, just started my 16 year old dog on calcitriol for her kidneys...maybe I should take a nip of it now and then???!!!

Rich66 · 11-20-2009, 07:08 PM

I've been chatting with the Calcitriol/PCa researcher and he claims it requires megadoses of calcitiriol specifically that aren't available. Can you launder some of your dog's out?

I found out the local Walgreens has 50,000 IU tablets by prescription. But..the rsearcher says it can't be true calcitriol so it isn't applicable. my last e-mail to him, I asked if that means megadoses of D3 or the like might have any benefit/synergy. No word back yet. They, of course, are working on a wiz bang Calcitriol formulation. The comparison between Vit D and Metformin seems promising so..maybe....