Supplemental estrogen and caloric restriction reduce obesity-induced periprostatic white adipose inflammation in mice.

Obesity is associated with an increased incidence of high-grade prostate cancer (PC) and worse prognosis for PC patients. Recently, we showed in men that obesity-related periprostatic white adipose tissue (WAT) inflammation, characterized by macrophages surrounding dead or dying adipocytes forming crown-like structures, was associated with high-grade PC. Possibly, interventions that suppress periprostatic WAT inflammation will improve outcomes for men with PC. Here, we tested the hypothesis that supplemental 17ß-estradiol (E2) could decrease periprostatic WAT inflammation in obese male mice. Mice were fed a high-fat diet to induce periprostatic WAT inflammation before being treated with supplemental E2. E2 supplementation suppressed caloric intake, induced weight loss, decreased periprostatic WAT inflammation and downregulated the expression of genes linked to inflammation including Cd68, Mcp1 and Tnf. Similar to the effects of E2 supplementation, treatment with diethylstilbestrol, a synthetic estrogen, also suppressed caloric intake and reduced periprostatic WAT inflammation. To determine whether the observed effects of supplemental estrogen could be reproduced by caloric restriction (CR) alone, obese mice were put on a 30% CR diet. Like estrogen treatment, CR was effective in reducing body weight, periprostatic WAT inflammation and the expression of pro-inflammatory genes. Transcriptomic analyses of periprostatic fat showed that obesity was associated with enrichment in inflammatory response pathways, which were normalized by both supplemental E2 and CR. Taken together, these findings strengthen the rationale for future efforts to determine whether either CR or supplemental estrogen will decrease periprostatic WAT inflammation and thereby improve outcomes for men with PC.

An inducible cytochrome P450 3A4-dependent vitamin D catabolic pathway.

Vitamin D(3) is critical for the regulation of calcium and phosphate homeostasis. In some individuals, mineral homeostasis can be disrupted by long-term therapy with certain antiepileptic drugs and the antimicrobial agent rifampin, resulting in drug-induced osteomalacia, which is attributed to vitamin D deficiency. We now report a novel CYP3A4-dependent pathway, the 4-hydroxylation of 25-hydroxyvitamin D(3) (25OHD(3)), the induction of which may contribute to drug-induced vitamin D deficiency. The metabolism of 25OHD(3) was fully characterized in vitro. CYP3A4 was the predominant source of 25OHD(3) hydroxylation by human liver microsomes, with the formation of 4ß,25-dihydroxyvitamin D(3) [4ß,25(OH)(2)D(3)] dominating (V(max)/K(m) = 0.85 ml · min(-1) · nmol enzyme(-1)). 4ß,25(OH)(2)D(3) was found in human plasma at concentrations comparable to that of 1α,25-dihydroxyvitamin D(3), and its formation rate in a panel of human liver microsomes was strongly correlated with CYP3A4 content and midazolam hydroxylation activity. Formation of 4ß,25(OH)(2)D(3) in primary human hepatocytes was induced by rifampin and inhibited by CYP3A4-specific inhibitors. Short-term treatment of healthy volunteers (n = 6) with rifampin selectively induced CYP3A4-dependent 4ß,25(OH)(2)D(3), but not CYP24A1-dependent 24R,25-dihydroxyvitamin D(3) formation, and altered systemic mineral homeostasis. Our results suggest that CYP3A4-dependent 25OHD(3) metabolism may play an important role in the regulation of vitamin D(3) in vivo and in the etiology of drug-induced osteomalacia.

Simultaneous measurement of plasma vitamin D(3) metabolites, including 4ß,25-dihydroxyvitamin D(3), using liquid chromatography-tandem mass spectrometry.

Simultaneous and accurate measurement of circulating vitamin D metabolites is critical to studies of the metabolic regulation of vitamin D and its impact on health and disease. To that end, we have developed a specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method that permits the quantification of major circulating vitamin D(3) metabolites in human plasma. Plasma samples were subjected to a protein precipitation, liquid-liquid extraction, and Diels-Alder derivatization procedure prior to LC-MS/MS analysis. Importantly, in all human plasma samples tested, we identified a significant dihydroxyvitamin D(3) peak that could potentially interfere with the determination of 1α,25-dihydroxyvitamin D(3) [1α,25(OH)(2)D(3)] concentrations. This interfering metabolite has been identified as 4ß,25-dihydroxyvitamin D(3) [4ß,25(OH)(2)D(3)] and was found at concentrations comparable to 1α,25(OH)(2)D(3). Quantification of 1α,25(OH)(2)D(3) in plasma required complete chromatographic separation of 1α,25(OH)(2)D(3) from 4ß,25(OH)(2)D(3). An assay incorporating this feature was used to simultaneously determine the plasma concentrations of 25OHD(3), 24R,25(OH)(2)D(3), 1α,25(OH)(2)D(3), and 4ß,25(OH)(2)D(3) in healthy individuals. The LC-MS/MS method developed and described here could result in considerable improvement in quantifying 1α,25(OH)(2)D(3) as well as monitoring the newly identified circulating metabolite, 4ß,25(OH)(2)D(3).

A Strategy to Delay the Development of Cisplatin Resistance by Maintaining a Certain Amount of Cisplatin-Sensitive Cells.

Cisplatin (ddp), which is commonly employed in the treatment of many advanced cancers, often results in initial therapeutic success; however, rapid progression of ddp-resistant cells remains the main reason for treatment failure. Facd with such a problem, we investigated the fitness differences between ddp-sensitive and ddp-resistant cell lines. We found that the growth of ddp-resistant cells was significantly slower than that of sensitive cells due to elevated ROS levels, which suggested that the ddp resistance mechanisms may have negative impacts on the growth of resistant cells. Furthermore, we observed that, when mixed with ddp-sensitive cells, ddp-resistant cells failed to compete, and the growth of ddp-resistant cells could therefore be suppressed by treatment in vivo. We propose a mathematical model parameterized based on in vivo experiments to describe the allometric growth of tumors consisting of two competing subclones. According to our model, a quantitative strategy with a variant drug-dosing interval is proposed to control tumor growth. Taking advantage of intratumoral competition, our strategy with appropriate dosing intervals could remarkably delay the development of ddp resistance and prolong overall survival. Maintaining a certain number of ddp-sensitive cells rather than eradicating the tumor with continuous treatment is feasible for future tumor treatment.

A highly selective and sensitive near-infrared fluorescent probe for imaging of hydrogen sulphide in living cells and mice.

Hydrogen sulphide (H2S), the third endogenous gaseous signalling molecule, has attracted attention in biochemical research. The selective detection of H2S in living systems is essential for studying its functions. Fluorescence detection methods have become useful tools to explore the physiological roles of H2S because of their real-time and non-destructive characteristics. Herein we report a near-infrared fluorescent probe, NIR-HS, capable of tracking H2S in living organisms. With high sensitivity, good selectivity and low cytotoxicity, NIR-HS was able to recognize both the exogenous and endogenous H2S in living cells. More importantly, it realized the visualization of endogenous H2S generated in cells overexpressing cystathionine ß-synthase (CBS), one of the enzymes responsible for producing endogenous H2S. The probe was also successfully applied to detect both the exogenous and endogenous H2S in living mice. The superior sensing properties of the probe render it a valuable research tool in the H2S-related medical research.

The relationship of vitamin D status, smoking, and colorectal adenoma: a retrospective study in an ethnically diverse community.

OBJECTIVE: Circulating 25-hydroxyvitamin D (25OHD) level is suggested to be negatively correlated with risk of colorectal cancer (CRC) and colorectal adenoma (CRA), but most of the epidemiological data were originated amongst Caucasians and African Americans. This study aimed to investigate the relationship between vitamin D status, smoking and CRA in an ethnically diverse community with a high Hispanic density. METHODS: In this retrospective study, we included 233 patients who underwent complete colonoscopies from 2009 to 2011, and their serum 25OHD levels in the winter season had been measured. Among them, 65 adenoma cases and 168 adenoma-free controls were identified and evaluated for the association of CRA with smoking, ethnicity and serum 25OHD level using unstratified and stratified multivariate logistic regression analyses. RESULTS: In our study participants, the mean serum 25OHD level and the percentage of Hispanics were lower in the adenoma group versus the control group, while no black-white difference was noted in the CRA prevalence. When adjusted for 25OHD level, the lower rate of adenoma in Hispanics compared to non-Hispanics was attenuated and became statistically insignificant. A mild protective effect of vitamin D (6% reduction) on the CRA risk was found significant for active smokers, but not for non-smokers. A detrimental impact of smoking in the CRA risk was only shown among non-Hispanic patients, but not among Hispanics irrespective of vitamin D status. CONCLUSIONS: Our data suggest a marked distinction between Hispanics and non-Hispanics in the risk of CRA. The reduced adenoma prevalence among Hispanics vs. non-Hispanics could be partially explained by vitamin D status, cigarette smoking and their interactions. Future larger-sized multi-center studies on vitamin D status and ethnicity, as well as dietary, behavioral, genetic factors and their interactions for CRA and CRC are needed. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Obesity, metabolic factors, and colorectal adenomas: a retrospective study in a racially diverse New York State Hospital.

OBJECTIVE: We studied a racially diverse population and the relationship with colorectal adenomas (CA) further looking for risks related to BMI and metabolic factors. DESIGNS: Seven hundred seventy-nine patients who underwent screening colonoscopies between 2007 and 2009 meeting exclusion criteria were included. To evaluate the association between race, BMI, and other metabolic factors with having one or more CA detected at colonoscopy, adjusted odds ratios and 95 % CI were estimated using unconditional logistic regression models. OUTCOMES: CA were detected in 167 out of 779 (21.4 %) patients. Compared to Whites, Hispanics were less likely to have one or more adenomas detected during a screening colonoscopy (OR = 0.52, 95 % CI, 0.31-0.88; p = 0.01). There was no significant statistical difference between Blacks and Whites, or other races and Whites. There was an association between the presence of CA and smoking (OR = 1.57, 95 % CI, 1.02-2.43; p = 0.04). CONCLUSION: Our results showed that Hispanics were less likely to have an adenoma detected during a screening colonoscopy than Whites. No statistical significant difference was found between patients with metabolic factors and the presence of colorectal adenoma.

Human PXR-mediated induction of intestinal CYP3A4 attenuates 1α,25-dihydroxyvitamin D3 function in human colon adenocarcinoma LS180 cells.

Oxidative catabolism of 1α,25-dihydroxyvitamin D(3) [1α,25(OH)(2)D(3)] is mediated by either CYP24A1 or CYP3A4. In this paper, we tested whether induction of CYP3A4 in the LS180 intestinal cell model enhances clearance of 1α,25(OH)(2)D(3) and blunts its hormonal effect on expression of the apical membrane calcium transport protein, TRPV6. Treatment with the hPXR agonist rifampin significantly increased CYP3A4 mRNA content and catalytic activity, but had no effect on CYP24A1 or TRPV6 mRNA content. Pre-treating cells with rifampin for 48h, prior to a 24h 1α,25(OH)(2)D(3) treatment phase, was associated with a subsequent 48% increase in the elimination of 1α,25(OH)(2)D(3) and a 35% reduction of peak TRPV6 mRNA. Introduction of the CYP3A4 inhibitor, 6',7'-dihydroxybergamottin, an active inhibitor in grapefruit juice, reversed the effects of rifampin on 1α,25(OH)(2)D(3) clearance and TRPV6 expression. Over-expression of hPXR in LS180 cells greatly enhanced the CYP3A4 responsiveness to rifampin pretreatment, and elicited a greater relative suppression of TRPV6 expression and an increase in 1α,25(OH)(2)D(3) disappearance rate, compared to vector expressed cells, following hormone administration. Together, these results suggest that induction of CYP3A4 in the intestinal epithelium by hPXR agonists can result in a greater metabolic clearance of 1α,25(OH)(2)D(3) and reduced effects of the hormone on the intestinal calcium absorption, which may contribute to an increased risk of drug-induced osteomalacia/osteoporosis in patients receiving chronic therapy with potent hPXR agonists. Moreover, ingestion of grapefruit juice in the at-risk patients could potentially prevent this adverse drug effect.