Pre-operative levels of angiopoietin protein-like 3 (ANGPTL3) in women diagnosed with high-grade serous carcinoma of the ovary.

Cancer cells need constant supplies of lipids to survive and grow. Lipid dependence has been observed in various types of cancer, including high-grade serous ovarian carcinomas (HGSOC), which is a lethal form of gynecological malignancy. ANGPTL3, PCSK9, and Apo CIII are pivotal lipid-modulating factors, and therapeutic antibodies have been developed against each one (Evinacumab, Evolocumab and Volanesorsen, respectively). The roles -if any- of ANGPTL3, PCSK9, and Apo CIII in HGSOC are unclear. Moreover, levels of these lipid-modulating factors have never been reported before in HGSOC. In this study, circulating levels of ANGPTL3, PCSK9, and Apo CIII, along with lipid profiles, are examined to verify whether one or many of these lipid-regulating factors are associated with HGSOC. Methods ELISA kits were used to measure ANGPTL3, PCSK9 and Apo CIII levels in plasma samples from 31 women with HGSOC and 40 women with benign ovarian lesions (BOL) before treatment and surgery. A Roche Modular analytical platform measured lipid panels, Apo B and Lp(a) levels.Results ANGPTL3 levels were higher in women with HGSOC (84 ng/mL, SD: 29 ng/mL, n = 31) than in women with BOL (67 ng/mL, SD: 31 ng/mL, n = 40; HGSOC vs. BOL P = 0.019). Associations between the lipid panel and ANGPTL3, and the inverse relationship between HDL-cholesterol and triglycerides, were present in women with BOL but not with HGSOC. PCSK9 and Apo CIII were not associated with HGSOC.Conclusions In this cohort of 71 women, ANGPTL3 levels were increased in HGSOC patients. The presence of HGSOC disrupted the classic inverse relationship between HDL and triglycerides, as well as the association between the lipid panel and ANGPTL3. These associations were only maintained in cancer-free women. Given the availability of Evinacumab, a therapeutic antibody against ANGPTL3, the current finding prompts an assessment of whether ANGPTL3 inhibition has therapeutic potential in HGSOC.

Relationship Between Diet Quality and Statin Use Among Adults With Metabolic Syndrome From the CARTaGENE Cohort.

Background: In metabolic syndrome (MetS), cardiovascular disease (CVD) risk reduction relies on the complementary use of diet and lipid-lowering medication. Evidence suggests that initiating such medication may impede diet quality. The objective of this study was to evaluate the relationship between diet quality and statin use among adults with MetS and free of CVD from the Province of Québec. Methods: This cross-sectional study included 2481 adults with MetS (40-69 years of age) from the CARTaGENE Québec population-based cohort, of whom 463 self-reported using statin monotherapy. Diet was assessed using the Canadian Dietary History Questionnaire II, a food- frequency questionnaire, and diet quality was assessed using the Alternative Healthy Eating Index (AHEI). Results: In multivariable-adjusted linear regression models, statin users had lower AHEI (%) compared with nonusers (users: 40.0; 95% confidence interval [CI], 38.9, 41.2 vs nonusers: 41.2; 95% CI, 40.4, 42.0; P = 0.03] because of a lower consumption of vegetables and whole grains. Stratified interaction analyses showed that the lower diet quality among statin users was mostly prevalent among men aged ≥ 50 years and women aged ≥ 60 years, among individuals with annual household incomes of < $50,000 and persons who self-reported history of high blood pressure. Conclusions: In this cohort of adults with MetS from Quebéc, the use of statin monotherapy in primary prevention of CVD was associated with a slightly lower diet quality. These data suggest suboptimal complementarity between diet quality and use of cholesterol-lowering medication in primary prevention of CVD in MetS.

Contexte: Dans le syndrome métabolique, la réduction du risque de maladie cardiovasculaire repose sur la complémentarité entre une saine alimentation et l'utilisation d'hypolipidémiants. Des évidences suggèrent que l'initiation d'un traitement médicamenteux hypolipémiant influencerait négativement la qualité de l'alimentation. Cette étude avait pour objectif de déterminer la relation entre la qualité de l'alimentation et l'utilisation de statines chez des adultes avec un syndrome métabolique, mais sans maladie cardiovasculaire, au Québec. Méthodologie: Cette étude transversale comptait 2481 adultes avec un syndrome métabolique (âgés de 40 à 69 ans) provenant de la cohorte CARTaGENE, représentative de la population du Québec, dont 463 sujets ayant autodéclaré qu'ils prenaient une statine en monothérapie. L'alimentation des sujets a été évaluée à l'aide du Canadian Dietary History Questionnaire II, un questionnaire de fréquence alimentaire, et la qualité de l'alimentation a été évaluée à l'aide de l'Alternative Healthy Eating Index (AHEI). Résultats: Dans des modèles de régression linéaire multivariée, les utilisateurs de statines ont présenté un indice AHEI (%) plus faible en comparaison aux non-utilisateurs (utilisateurs : 40,0; intervalle de confiance [IC] à 95 % : 38,9-41,2 vs non-utilisateurs : 41,2; IC à 95 % : 40,4-42,0; p = 0,03), en raison d'une plus faible consommation de légumes et de grains entiers. Selon des analyses d'interaction stratifiées, la plus faible qualité nutritionnelle chez les utilisateurs de statines était particulièrement prévalente chez les hommes de ≥ 50 ans et les femmes de ≥ 60 ans, chez les personnes dont le revenu annuel du ménage était < 50 000 dollars et chez les personnes ayant autodéclaré des antécédents d'hypertension. Conclusions: Dans cette cohorte d'adultes du Québec avec un syndrome métabolique, l'utilisation de statines en monothérapie dans la prévention des maladies cardiovasculaires était associée à une alimentation dont la qualité était légèrement plus faible. Ces données suggèrent une complémentarité sous-optimale entre la qualité de l'alimentation et l'utilisation d'hypocholestérolémiants en prévention des maladies cardiovasculaires chez les personnes avec un syndrome métabolique.

Dysregulation of Cholesterol Homeostasis in Ovarian Cancer.

Cholesterol plays an essential role in maintaining the rigidity of cell membranes and signal transduction. Various investigations confirmed empirically that the dysregulation of cholesterol homeostasis positively correlates with tumor progression. More specifically, recent studies suggested the distinct role of cholesterol in ovarian cancer cell proliferation, metastasis and chemoresistance. In this review, we summarize the current findings that suggest the contribution of cholesterol homeostasis dysregulation to ovarian cancer progression and resistance to anti-cancer agents. We also discuss the therapeutic implications of cholesterol-lowering drugs in ovarian cancer.

Relationship between lifestyle habits and cardiovascular risk factors in familial hypercholesterolemia.

BACKGROUND AND AIM: Little is known about the cardioprotective potential of a healthy lifestyle in familial hypercholesterolemia (FH). The objective of this study was to evaluate the relationship between lifestyle and cardiovascular risk factors in adults with FH. METHODS AND RESULTS: This cross-sectional study leveraged data from the CARTaGENE Quebec population-based cohort (Canada). Participants with FH were identified using the validated Simplified Canadian Definition for FH. A healthy lifestyle score (HLS), ranging from 0 to 5, was calculated per adherence to 5 lifestyle habits: 1) not smoking; 2) being physically active (≥150 min/week of moderate or vigorous physical activity); 3) eating a healthy diet (Alternate Healthy Eating Index ≥50%); 4) having a light to moderate alcohol consumption (men: 1-30 g/day; women: 1-15 g/day); and 5) sleeping 7-8 h/day. Among the 122 included individuals (women, n = 78; men, n = 44; mean age ± SD: 57.3 ± 6.7 years), 92 (75.4%) had a HLS ≤3/5, while only 5 (4.1%) had a HLS of 5/5. After adjustments for sex, age, body mass index, and lipid-lowering medication use, we found no evidence of an association between the HLS and concentrations of LDL-cholesterol (ß = 0.04, 95% CI = -0.08, 0.15 mmol/L; P = 0.54). However, the HLS was favorably associated with HbA1c levels (ß = -0.07, 95% CI = -0.13, -0.01%; P = 0.02), and statistical trends suggested favorable associations with HDL-cholesterol (ß = 0.06, 95% CI = -0.02, 0.14 mmol/L; P = 0.06) and waist circumference (ß = -2.22, 95% CI = -4.62, 0.17 cm; P = 0.07). CONCLUSION: This study suggests that a healthy lifestyle is favorably associated with CVD risk factors in adults with FH.

Are Lipid-Lowering and Antihypertensive Medications Used as Complements to Heart-Healthy Diets? A Scoping Review.

In cardiovascular disease (CVD) prevention, whether antihypertensive and lipid-lowering medications are used as complements to heart-healthy diets has not been thoroughly assessed. This scoping review aimed to 1) analyze observational studies that assessed the relationship between diet and antihypertensive/lipid-lowering medication use and 2) evaluate whether medication was used as a complement to heart-healthy dietary intakes. We searched MEDLINE, Embase, Web of Science, and CINAHL through 14 January, 2023, for studies that assessed either 1) intraindividual changes in diet associated with lipid-lowering/antihypertensive medication initiation or use or 2) interindividual differences in diet between users and nonusers of these medications. A total of 17 studies were included. Of those, 3 prospectively assessed the intraindividual changes in diet associated with medication initiation or use, but none documented potential changes in diet prior to medication initiation. The 14 other studies compared dietary intakes of medication users and nonusers, most of which also relied on an incomplete assessment of the temporal dynamics between diet and medication use as they employed cross-sectional (n = 12) or repeated cross-sectional (n = 2) designs. Data from 8 studies, including 4 of the 5 studies from Europe, suggested that medication was used as a complement to heart-healthy diets, whereas data from the 9 other studies, including the 4 conducted in the United States, provided no such evidence, indicating potential between-country differences in this relationship. Finally, no studies investigated how the dynamics between diet and medication use influenced the long-term CVD risk. This scoping review suggests that the current literature on the relationship between lipid-lowering/antihypertensive medication use and diet provides an incomplete perspective on how medication may influence diet in CVD prevention. Prospective studies assessing intraindividual changes in diet associated with medication initiation and use and how these dynamics influence the CVD risk are thus needed.

Circulating levels of PCSK9, ANGPTL3 and Lp(a) in stage III breast cancers.

BACKGROUND / SYNOPSIS: Cholesterol and lipids play an important role in sustaining tumor growth and metastasis in a large variety of cancers. ANGPTL3 and PCSK9 modify circulating cholesterol levels, thus availability of lipids to peripheral cells. Little is known on the role, if any, of circulating lipid-related factors such as PCSK9, ANGPTL3 and lipoprotein (a) in cancers. OBJECTIVE/PURPOSE: To compare circulating levels of PCSK9, ANGPTL3, and Lp(a) in women with stage III breast cancer versus women with premalignant or benign breast lesions. METHODS: Twenty-three plasma samples from women diagnosed with a stage III breast cancer (ductal, lobular or mixed) were matched for age with twenty-three plasma samples from women bearing premalignant (stage 0, n = 9) or benign (n = 14) breast lesions. The lipid profile (Apo B, total cholesterol, HDL cholesterol and triglycerides levels) and Lp(a) were measured on a Roche Modular analytical platform, whereas LDL levels were calculated with the Friedewald formula. ANGPTL3 and PCSK9 plasma levels were quantitated by ELISA. All statistical analyses were performed using SAS software version 9.4. RESULTS: PCSK9 levels were significantly higher in women with stage III breast cancer compared to age-matched counterparts presenting a benign lesion (95.9 ± 27.1 ng/mL vs. 78.5 ± 19.3 ng/mL, p < 0.05, n = 14). Moreover, PCSK9 levels positively correlated with breast disease severity (benign, stage 0, stage III) (Rho = 0.34, p < 0.05, n = 46). In contrast, ANGPTL3 and Lp(a) plasma levels did not display any association with breast disease status and lipids did not correlate with disease severity. CONCLUSION: In this small cohort of 46 women, PCSK9 levels tended to increase with the severity of the breast disease. Given that PCSK9 plays an important role in maintaining cholesterolemia, and a potential role in tumor evasion, present results warrant further investigation into a possible association between PCSK9 levels and breast cancer severity in larger cohorts of women.

Relationships between circulating 25(OH) vitamin D, leptin levels and visceral adipose tissue volume: results from a 1-year lifestyle intervention program in men with visceral obesity.

BACKGROUND/OBJECTIVES: Obesity has been associated with elevated leptinemia and vitamin D deficiency. To date, whether there is an association between vitamin D and leptin levels independent from adiposity remains uncertain. Our objective was to investigate the associations between changes in 25(OH) vitamin D levels, changes in adiposity variables, and changes in leptin levels produced by a 1-year lifestyle intervention program. SUBJECTS/METHODS: Sedentary men (n = 113) with abdominal obesity, dyslipidemic, and non-vitamin D supplemented were involved in a 1-year lifestyle modification program. Subjects were individually counseled by a kinesiologist and a nutritionist once every 2 weeks during the first 4 months with subsequent monthly visits in order to elicit a 500 kcal daily energy deficit and to increase physical activity/exercise habits. Adiposity mapping by computed tomography and cardiometabolic biomarkers, as well as vitamin D measurements were performed at baseline and at the 1-year visit. RESULTS: The 1-year intervention resulted in a 26% decrease in visceral adipose tissue volume (from 1951 ± 481 to 1463 ± 566 cm3), a 27% decrease in leptin levels (from 12.0 ± 8.1 to 8.5 ± 7.8 ng/mL) and a 27% increase in plasma 25(OH) vitamin D concentrations (from 50 ± 18 to 60 ± 18 nmol/L, p < 0.0001). One-year increases in 25(OH) vitamin D levels were inversely correlated with 1-year changes in leptin levels (r = -0.41, p < 0.001). The association remained significant after adjustment for 1-year changes in various adiposity indices: visceral adipose tissue (r = -0.30, p = 0.0019), subcutaneous adipose tissue (r = -0.35, p = 0.0004), total abdominal adipose tissue (r = -0.31, p = 0.0015), and fat mass (r = -0.31, p = 0.001). CONCLUSIONS: In response to a 1-year lifestyle intervention, changes in 25(OH) vitamin D levels were independently associated with changes in leptinemia after adjustment for adiposity changes. This finding supports a possible physiological link between leptinemia and 25(OH) vitamin D levels independent from adiposity and underscores the role of lifestyle modifications leading to lowered leptinemia in the clinical management of vitamin D deficiency.

Dietary intake of branched-chain amino acids in a mouse model of Alzheimer's disease: Effects on survival, behavior, and neuropathology.

INTRODUCTION: High levels of plasmatic branched-chain amino acids (BCAA), commonly used as dietary supplements, are linked to metabolic risk factors for Alzheimer's disease (AD). BCAA directly influence amino acid transport to the brain and, therefore, neurotransmitter levels. We thus investigated the impact of BCAA on AD neuropathology in a mouse model. METHODS: 3xTg-AD mice were fed either a control diet or a high-fat diet from 6 to 18 months of age. For the last 2 months, dietary BCAA content was adjusted to high (+50%), normal (+0%), or low (-50%). RESULTS: Mice fed a BCAA-supplemented high-fat diet displayed higher tau neuropathology and only four out of 13 survived. Mice on the low-BCAA diet showed higher threonine and tryptophan cortical levels while performing better on the novel object recognition task. DISCUSSION: These preclinical data underscore a potential risk of combining high-fat and high BCAA consumption, and possible benefits from BCAA restriction in AD.

Changes in circulating vitamin D levels with loss of adipose tissue.

PURPOSE OF REVIEW: Low vitamin D levels have been extensively reported in obesity. Thus, the pandemic of obesity has been paralleled by a high prevalence of low vitamin D status. Given the well documented associations linking poor vitamin D status to adverse health outcomes (diabetes, cardiovascular disease, cancers, all-cause mortality), a proper understanding of the mechanisms linking excess adiposity to low vitamin D status is key to identify and implement effective interventions to replenish vitamin D levels in obese individuals. In this review, we will discuss recent literature investigating the effects of adipose tissue volume loss through energy restriction and/or physical activity on circulating 25-hydroxyvitamin D [25(OH)D] levels. RECENT FINDINGS: Improvements of circulating 25(OH)D levels with adiposity loss through lifestyle interventions without supplementation is being reported by a growing number of studies, including recent randomized controlled trials. SUMMARY: Low 25(OH)D is one of the metabolic disturbances associated with excess adiposity, particularly visceral adiposity. Recommendations for the treatment of obesity-related vitamin D deficiency should emphasize the role of visceral adiposity loss through healthy lifestyle habits, in conjunction with weight-adjusted vitamin D supplementation, not only to replenish 25(OH)D levels but also to address other visceral adiposity-related disturbances, such as insulin resistance, inflammation, hypertension, and dyslipidemia.

Ruptured aneurysmal subarachnoid hemorrhage in the emergency department: Clinical outcome of patients having a lumbar puncture for red blood cell count, visual and spectrophotometric xanthochromia after a negative computed tomography.

OBJECTIVES: Over the last decade, computed tomography scanners have gained resolution and have become the standard of care in the investigation of neurologically intact patients suffering from acute headache. The added value of the combined assessment of red blood cells count, visual and spectrophotometric xanthochromia, to detect ruptured aneurysmal subarachnoid hemorrhage (ASAH) following a negative head computed tomography (NHCT) was studied. METHODS: The population consisted of all patients who had cerebrospinal fluid tested for spectrophotometric xanthochromia between 2003 and 2009 identified through the clinical-laboratory database and who met all the inclusion criteria: >14 years old, had an initial Glasgow Coma Score of 15, a non-traumatic acute headache with a suspected subarachnoid hemorrhage recorded in the initial ED differential diagnosis and an initial negative head CT scan. RESULTS: A total of 706 patients were included. LP identified 5 ASAH (prevalence: 0.7%). In these patients, LP parameters were as follows: high red blood cell count (from 1310 to 63,000×10(6)/L), positive visual xanthochromia in 4 out of 5 ASAH, and positive spectrophotometric xanthochromia in 5 out of 5 ASAH. All ASAH patients were neurologically intact after intervention. No deaths or missed ASAH were reported. Angiographies were performed on 127 patients (19.5%) of which 47 (34.1%) had positive xanthochromia (visual or spectrophotometric). CONCLUSIONS: Considering the low prevalence of ASAH following an NHCT, intense resources were utilized to identify all 5 ASAH. Lumbar puncture analyses combining red blood cell count, visual and spectrophotometric xanthochromia identified all ASAH, allowing intervention and a positive clinical outcome. Our data support 1) that LP identifies the presence of a ruptured ASAH after an NHCT and 2)` that a guide to define a subpopulation of patients who would benefit from a lumbar puncture after an NHCT would be desirable.

Predicting chemotherapy response to paclitaxel with 18F-Fluoropaclitaxel and PET.

UNLABELLED: Paclitaxel is used as a chemotherapy drug for the treatment of various malignancies, including breast, ovarian, and lung cancers. To evaluate the potential of a noninvasive prognostic tool for specifically predicting the resistance of tumors to paclitaxel therapy, we examined the tumoral uptake of (18)F-fluoropaclitaxel ((18)F-FPAC) in mice bearing human breast cancer xenografts by using small-animal-dedicated PET and compared (18)F-FPAC uptake with the tumor response to paclitaxel treatment. METHODS: PET data were acquired after tail vein injection of approximately 9 MBq of (18)F-FPAC in anesthetized nude mice bearing breast cancer xenografts. Tracer uptake in reconstructed images was quantified by region-of-interest analyses and compared with the tumor response, as measured by changes in tumor volume, after treatment with paclitaxel. RESULTS: Mice with tumors that progressed demonstrated lower tumoral uptake of (18)F-FPAC than mice with tumors that did not progress or that regressed (r = 0.55, P < 0.02; n = 19), indicating that low (18)F-FPAC uptake was a significant predictor of chemoresistance. Conversely, high (18)F-FPAC uptake predicted tumor regression. This relationship was found for mice bearing xenografts from cell lines selected to be either sensitive or intrinsically resistant to paclitaxel in vitro. CONCLUSION: PET data acquired with (18)F-FPAC suggest that this tracer holds promise for the noninvasive quantification of its distribution in vivo in a straightforward manner. In combination with approaches for examining other aspects of resistance, such quantification could prove useful in helping to predict subsequent resistance to paclitaxel chemotherapy of breast cancer.

Estimation of paclitaxel biodistribution and uptake in human-derived xenografts in vivo with (18)F-fluoropaclitaxel.

UNLABELLED: Paclitaxel (PAC) is widely used as a chemotherapy drug in the treatment of various malignancies, including breast, ovarian, and lung cancers. We examined the biodistribution of (18)F-fluoropaclitaxel ((18)F-FPAC) in mice with and without human breast cancer tumor xenografts by use of small-animal-dedicated PET (microPET) and clinically practical semiquantitative methods. We compared the PET data to data derived from direct harvesting and analysis of blood, organs, and breast carcinoma xenografts. METHODS: PET data were acquired after tail vein injection of (18)F-FPAC in nude mice. Tracer biodistribution in reconstructed images was quantified by region-of-interest analysis. Biodistribution also was assessed by harvesting and analysis of dissected organs, tumors, and blood after coadministration of (18)F-FPAC and (3)H-PAC. (18)F content in each tissue was assessed with a gamma-well counter, and (3)H content was quantified by scintillation counting of solubilized tissue after (18)F radioactive decay. RESULTS: The distributions of (18)F-FPAC and (3)H-PAC were very similar, with the highest concentrations in the small intestine, the lowest concentrations in the brain, and intermediate concentrations in tumor. Uptake in these and other tissues was not inhibited by the presence of more pharmacologic doses of unlabeled PAC. Administration of the P-glycoprotein modulator cyclosporine doubled the uptake of both (18)F-FPAC and (3)H-PAC into tumor. CONCLUSION: PET studies with (18)F-FPAC can be used in conjunction with clinically practical quantification methods to yield estimates of PAC uptake in breast cancer tumors and normal organs noninvasively.

How estrogen-specific proteins discriminate estrogens from androgens: a common steroid binding site architecture.

Steroid hormones play an essential role in a wide range of physiological and pathological processes, such as growth, metabolism, aging, and hormone-sensitive cancers. Estrogens are no exception and influence growth, differentiation, and functioning of many target tissues, such as the mammary gland, uterus, hypothalamus, pituitary, bone, and liver. Although very similar in structure, each steroid class (i.e., estrogens, androgens, progestins, mineral corticoids, or glucocorticoids) is responsible for distinct physiological processes. To permit specific biological responses for a given steroid class, specific proteins are responsible for steroid bioactivation, action, and inactivation, yet they have low or no affinity to other classes. Estrogens make no exception and possess their own set of related proteins. To understand the molecular basis underlying estrogen recognition from other steroids, structural features of estrogen-specific proteins were analyzed along with their ability to discriminate between steroid hormones belonging to different classes. Hence, the study of all estrogen-specific proteins for which an atomic structure has been determined demonstrated that a common steroid-binding pocket architecture is shared by these proteins. This architecture is composed of the following elements: i) a glutamate residue acting as a proton acceptor coupled with a proton donor that interact with the steroid O3; ii) a proton donor (His or Ser) that interacts with O17; iii) a highly conserved sandwich-like structure providing steric hindrance and preventing C19 steroid from binding; and iv) several amino acid residues interacting with the C18. As these different estrogen-specific proteins are not related in overall sequence, the inference is that the steroid binding site in these proteins has originated by convergent evolution.

Pseudo-symmetry of C19 steroids, alternative binding orientations, and multispecificity in human estrogenic 17beta-hydroxysteroid dehydrogenase.

Steroids are implicated in many physiological processes, such as reproduction, aging, metabolism, and cancer. To understand the molecular basis for steroid recognition and discrimination, we studied the human estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD1) responsible for the last step in the bioactivation of all estrogens. Here we report the first observation of the conversion of dihydrotestosterone (DHT) into 3beta,17beta-androstanediol (3beta-diol) by 17beta-HSD1, an estrogenic enzyme studied for more than half a century. Kinetic observations demonstrate that both the 3beta-reduction of DHT into 3beta-diol (kcat = 0.040 s(-1)1; Km = 32 +/- 9 microM) and the 17beta-oxidation of DHT into androstandione (A-dione) (kcat = 0.19 s(-1); Km = 26 +/-6 microM) are catalyzed by 17beta-HSD1 via alternative binding orientation of the steroid. The reduction of DHT was also observed in intact cells by using HEK-293 cells stably transformed with 17beta-HSD1. The high-resolution structure of a 17beta-HSD1-C19-steroid (testosterone) complex solved at 1.54 A demonstrates that the steroid is reversibly oriented in the active site, which strongly supports the existence of alternative binding mode. Such a phenomenon can be explained by the pseudo-symmetric structure of C19-steroids. Our results confirm the role of the Leu149 residue in C18/C19-steroid discrimination and suggest a possible mechanism of 17beta-HSD1 in the modulation of DHT levels in tissues, such as the breast, where both the enzyme and DHT are present.

A concerted, rational design of type 1 17beta-hydroxysteroid dehydrogenase inhibitors: estradiol-adenosine hybrids with high affinity.

Human estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD type 1) catalyzes the final step in the synthesis of active estrogens that stimulate the proliferation of breast cancer cells. Based on the initial premise to make use of the binding energies of both the substrate and cofactor sites, and molecular modeling starting from the enzyme structure, several estradiol-adenosine hybrids were designed and synthesized. Among these hybrids, EM-1745 with a linker of 8-CH2 groups is proved to be the best competitive inhibitor with a Ki of 3.0 +/- 0.8 nM. The crystal structure of the EM-1745 enzyme complex at 1.6 A provides evidence at atomic resolution of strong interactions between both the steroid and cofactor moieties and the enzyme molecule, as illustrated by a deltaA-weighted 2Fo-Fc electron density map contoured at 3.0 delta. The substrate entry loop is further stabilized in this complex compared with previous complexes of the enzyme. These results confirm our initial strategy of combining studies of structural biology and enzyme mechanism in the inhibitor design, which may be applied to other steroidogenic enzymes involved in human diseases.

Purification, crystallization and preliminary X-ray diffraction results of human 17beta-hydroxysteroid dehydrogenase type 5.

17beta-Hydroxysteroid dehydrogenases (17beta-HSDs) catalyze the last step in the biosynthesis of all androgens and estrogens, thus playing a pivotal role in sex-hormone metabolism. Human 17beta-HSD type 5 (17beta-HSD5) catalyzes hydride transfer at the 17beta-hydroxy position, but possesses high sequence homology to 3alpha-hydroxysteroid dehydrogenases (3alpha-HSD). Two crystal forms of 17beta-HSD5 in an enzyme-testosterone-NADP ternary complex have been obtained under different crystallization conditions. A form I crystal obtained at pH 8.5 diffracted to 1.32 A. It belonged to space group P2(1), with unit-cell parameters a = 47.41, b = 77.16, c = 48.67 A, beta = 116.32 degrees. Form II crystals obtained at pH 6.5 diffracted to 2.0 A and belonged to space group P6(3), with unit-cell parameters a = b = 110.58, c = 56.89 A.