Over the past two decades, the question of whether vitamin D has a role in cancer incidence, progression, and mortality has been studied in detail. Colorectal, breast, and prostate cancers have been a particular area of focus; together, these three malignancies account for approximately 35% of cancer cases and 20% of cancer deaths in the United States, and as such are a major public health concern. Herein, we review and synthesize the epidemiological research regarding vitamin D, as measured by the biomarker 25-hydroxycholecalciferol [25(OH)D], and the incidence, progression, and mortality of these cancers. Overall, the results of observational studies of the relationship between 25(OH)D and colorectal cancer have revealed a consistent inverse association for incidence and mortality; while for breast cancer, results have generally demonstrated a relationship between higher 25(OH)D and lower risk for progression and mortality. In contrast, randomized, double-blind clinical trials conducted to date have generally failed to support these findings. For prostate cancer, there is no convincing evidence of an association between 25(OH)D and incidence, and inconsistent data for progression and mortality, though results of one open label clinical trial suggest that supplementation with 4000 IU/d of vitamin D3 may inhibit progression of the disease. Nonetheless, until the results of additional ongoing randomized, double-blind clinical trials are reported, it will be difficult to ascertain if vitamin D itself is related to a reduction in risk for some cancer endpoints, or whether high concentrations of the vitamin D biomarker 25(OH)D may instead serve as a marker for an overall beneficial risk factor profile.

The biological basis for documented in vivo bone-protective effects of turmeric-derived curcumin is unclear since curcumin is barely detectable in serum, being rapidly conjugated to form what is thought to be an inactive glucuronide. Studies were therefore undertaken to test the postulate that anti-resorptive effects of curcumin require deconjugation within bone to form the bioactive aglycone, and that ß-glucuronidase (GUSB), a deconjugating enzyme expressed by hematopoietic marrow cells, facilitates this site-specific transformation. Consistent with this postulate, aglycone, but not glucuronidated, curcumin inhibited RANKL-stimulated osteoclastogenesis, a key curcumin target in bone. Aglycone curcumin, expressed relative to total curcumin, was higher in bone marrow than in serum of curcumin-treated C57BL/6J mice, while remaining a minor component. Ex vivo, under conditions preventing further metabolism of the unstable aglycone, the majority of curcumin-glucuronide delivered to marrow in vivo was hydrolyzed to the aglycone, a process that was inhibited by treatment with saccharolactone, a GUSB inhibitor, or in mice having reduced (C3H/HeJ) or absent (mps/mps) GUSB activity. These findings suggest that curcumin, despite low systemic bioavailability, may be enzymatically activated (deconjugated) within GUSB-enriched bone to exert protective effects, a metabolic process that could also contribute to bone-protective effects of other highly glucuronidated dietary polyphenols.

Breast cancer (BCa) bone metastases (BMETs) drive osteolysis via a feed-forward loop involving tumoral secretion of osteolytic factors (e.g., PTHrP) induced by bone matrix-derived growth factors (e.g., TGFβ). In prior experiments, turmeric-derived curcumin inhibited in vivo BMET progression and in vitro TGFβ/Smad-signaling in a TGFβ-stimulated PTHrP-dependent human xenograft BCa BMET model (MDA-SA cells). However, it is unclear whether curcumin or curcumin-glucuronide mediates in vivo protection since curcumin-glucuronide is the primary circulating metabolite in rodents and in humans. Thus, effects of curcumin vs. curcumin-glucuronide on Smad-dependent TGFβ signaling were compared in a series of BCa cell lines forming TGFβ-dependent BMET in murine models, and tissue-specific metabolism of curcumin in mice was examined by LC-MS. While curcumin inhibited TGFβ-receptor-mediated Smad2/3 phosphorylation in all BCa cells studied (human MDA-SA, MDA-1833, MDA-2287, and murine 4T1 cells), curcumin-glucuronide did not. Similarly, curcumin, but not curcumin-glucuronide, blocked TGFβ-stimulated secretion of PTHrP from MDA-SA and 4T1 cells. Because the predominant serum metabolite, curcumin-glucuronide, lacked bioactivity, we examined tissuespecific metabolism of curcumin in mice. Compared to serum and other organs, free curcumin (both absolute and percentage of total) was significantly increased in bone, which was also a rich source of enzymatic deglucuronidation activity. Thus, curcumin, and not curcumin-glucuronide, appears to inhibit bone-tropic BCa cell TGFβ-signaling and undergo site specific activation (deconjugation) within the bone microenvironment. These findings suggest that circulating curcumin-glucuronide may act as a pro-drug that preferentially targets bone, a process that may contribute to the bone-protective effects of curcumin and other highly glucuronidated dietary polyphenols.

Conclusion:This study has demonstrated the perception of different tastes in a PWCA. This is the first known report of umami being identified as a unique taste in a PWCA. Variations in threshold taste concentrations compared to normal individuals indicate certain gustatory dysfunction.

Scope: Curcumin prevents bone loss in resorptive bone diseases and inhibits osteoclast formation, a key process driving bone loss. Curcumin circulates as an inactive glucuronide that can be deconjugated in situ by bone's high β-glucuronidase (GUSB) content, forming the active aglycone. Because curcumin is a common remedy for musculoskeletal disease, effects of microenvironmental changes consequent to skeletal development and/or disease on bone curcumin metabolism were explored.Methods and Results: Across sexual/skeletal development or between sexes in C57BL/6 mice ingesting curcumin (500 mg/kg), bone curcumin metabolism and GUSB enzyme activity were unchanged, except for >2-fold higher (p < 0.05) bone curcumin-glucuronide substrate levels in immature (4-6-week-old) mice. In ovariectomized (OVX) or bone metastasis-bearing female mice, bone substrate levels were also >2-fold higher. Aglycone curcumin levels tended to increase proportional to substrate such that the majority of glucuronide distributing to bone was deconjugated, including OVX mice where GUSB decreased by 24% (p < 0.01).

effects of tumoral estrogen signaling in an estrogen receptor-positive breast cancer bone metastasis model.

Turmeric extract, a mixture of curcumin and its demethoxy (DMC) and bisdemethoxy (BDMC) isomers, is used as an anti-inflammatory preparation in traditional Asian medicine. Curcumin is considered to be the major bioactive compound in turmeric but less is known about the relative anti-inflammatory potency and mechanism of the other components, their mixture, or the reduced in vivo metabolites. We quantified inhibition of the NF-κB pathway in cells, adduction to a peptide mimicking IκB kinase β, and the role of cellular glutathione as a scavenger of electrophilic curcuminoid oxidation products, suggested to be the active metabolites. Turmeric extracts (IC50 14.5 ± 2.9 μM), DMC (IC50 12.1 ± 7.2 μM), and BDMC (IC50 8.3 ± 1.6 μM), but not reduced curcumin, inhibited NF-κB similar to curcumin (IC50 18.2 ± 3.9 μM). Peptide adduction was formed with turmeric and DMC but not with BDMC, and this correlated with their oxidative degradation. Inhibition of glutathione biosynthesis enhanced the activity of DMC but not BDMC in the cellular assay. These findings suggest that NF-κB inhibition by curcumin and DMC involves their oxidation to reactive electrophiles, whereas BDMC does not require oxidation. Because it has not been established whether curcumin undergoes oxidative transformation in vivo, oxidation-independent BDMC may be a promising alternative to test in clinical trials.

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