ERβ Sensitizes Breast Cancer Cells to Retinoic Acid: Evidence of Transcriptional Crosstalk

Associations of plasma retinol and α-tocopherol levels with skeletal muscle health in Chinese children

Childhood is a critical period for muscle accumulation. Studies in elders have reported that antioxidant vitamins could improve muscle health. However, limited studies have assessed such associations in children. This study included 243 boys and 183 girls. A seventy-nine-item FFQ was used to investigate dietary nutrients intake. Plasma levels of retinol and α-tocopherol were measured using high-performance liquid chromatography with MS. Dual X-ray absorptiometry was used to assess appendicular skeletal muscle mass (ASM) and total body fat. The ASM index (ASMI) and ASMI Z-score were then calculated. Hand grip strength was measured using a Jamar® Plus+ Hand Dynamometer. Fully adjusted multiple linear regression models showed that for each unit increase in plasma retinol content, ASM, ASMI, left HGS and ASMI Z-score increased by 2·43 × 10-3 kg, 1·33 × 10-3 kg/m2, 3·72 × 10-3 kg and 2·45 × 10-3 in girls, respectively (P < 0·001-0·050). ANCOVA revealed a dose-response relationship between tertiles of plasma retinol level and muscle indicators (Ptrend: 0·001-0·007). The percentage differences between the top and bottom tertiles were 8·38 %, 6·26 %, 13·2 %, 12·1 % and 116 % for ASM, ASMI, left HGS, right HGS and ASMI Z-score in girls, respectively (Pdiff: 0·005-0·020). No such associations were observed in boys. Plasma α-tocopherol levels were not correlated with muscle indicators in either sex. In conclusion, high circulating retinol levels are positively associated with muscle mass and strength in school-age girls.

Modest Decreases in Endogenous All-trans-Retinoic Acid Produced by a Mouse Rdh10 Heterozygote Provoke Major Abnormalities in Adipogenesis and Lipid Metabolism

Pharmacological dosing of all-trans-retinoic acid (atRA) controls adiposity in rodents by inhibiting adipogenesis and inducing fatty acid oxidation. Retinol dehydrogenases (Rdh) catalyze the first reaction that activates retinol into atRA. This study examined postnatal contributions of Rdh10 to atRA biosynthesis and physiological functions of endogenous atRA. Embryonic fibroblasts from Rdh10 heterozygote hypomorphs or with a total Rdh10 knockout exhibit decreased atRA biosynthesis and escalated adipogenesis. atRA or a retinoic acid receptor (RAR) pan-agonist reversed the phenotype. Eliminating one Rdh10 copy in vivo (Rdh10^+/- ) yielded a modest decrease (≤25%) in the atRA concentration of liver and adipose but increased adiposity in male and female mice fed a high-fat diet (HFD); increased liver steatosis, glucose intolerance, and insulin resistance in males fed an HFD; and activated bone marrow adipocyte formation in females, regardless of dietary fat. Chronic dosing with low-dose atRA corrected the metabolic defects. These data resolve physiological actions of endogenous atRA, reveal sex-specific effects of atRA in vivo, and establish the importance of Rdh10 to metabolic control by atRA. The consequences of a modest decrease in tissue atRA suggest that impaired retinol activation may contribute to diabesity, and low-dose atRA therapy may ameliorate adiposity and its sequelae of glucose intolerance and insulin resistance.

Reduced expression of oestrogen receptor-β is associated with tumour invasion and metastasis in oestrogen receptor-α-negative human papillary thyroid carcinoma

Oestrogens play an important role in the development and progression of papillary thyroid carcinoma (PTC) through oestrogen receptor (ER)-α and -β, which may exert different or even opposing actions in PTC. The roles of ERβ in ERα-negative PTC are still not clear. This study investigated the expression dynamics of ERβ1 (wild-type ERβ) and its clinical significance in female ERα-negative PTC patients. ERβ1 expression was detected in thyroid tissues of 136 female patients diagnosed with PTC. The relationships between ERβ1 expression and clinicopathological/biological factors were also analysed in female ERα-negative PTC patients. The total score for ERβ1 was significantly lower in female ERα-negative PTC patients with LNM or ETE when compared to those without LNM or ETE (Z = -2.923, P = 0.003 and Z = -3.441, P = 0.001). Accordingly, the total score for ERβ1 was significantly higher in ERα-negative PTC patients expressing E-cadherin compared to patients negative for E-cadherin expression (Z = -2.636, P = 0.008). The total score was lower in ERα-negative PTC patients positive for VEGF expression compared to those negative for VEGF expression (Z = -1.914, P = 0.056). This preliminary study indicates that reduced expression of ERβ1 in female ERα-negative PTC patients is associated with greater progression of the disease. This may provide insights into the underlying molecular mechanisms of ERβ1 and could help design targeted approaches for treating or even preventing this disease.

Role of delta-like ligand-4 in chemoresistance against docetaxel in MCF-7 cells

As Notch receptors have been shown to induce chemoresistance, we hypothesized that delta-like ligand-4 (DLL4), a central Notch signalling ligand, might also participate in chemoresistance in breast cancer. To investigate this issue, overexpression of DLL4 was induced by transfection with expression vectors for DLL4 in the human breast cancer cell line Michigan cancer foundation-7 (MCF-7). It was found that DLL4 could be adaptively upregulated by docetaxel (DOC) treatment in a dose-dependent manner, but Notch1 was unaffected. Overexpression of DLL4 could significantly attenuate the cytotoxic effects of DOC by increasing Bcl-2 expression, while decreasing Bax expression, apoptosis rate and DNA damage. The protective effects of DLL4 made cells acquire chemoresistance against DOC and resulted in cancer cell survival. DLL4 is normally regarded as a regulator of vascular development. Our results expanded the understanding of DLL4. Since DLL4 may play an important role in the process of acquiring chemoresistance, it may be a promising target in overcoming chemoresistance in breast cancer.

Bioanalytical LC-MS Method for the Quantification of Plasma Androgens and Androgen Glucuronides in Breast Cancer

The physiological and pathological development of the breast is strongly affected by the hormonal milieu consisting of steroid hormones. Mass spectrometry (MS) technologies of high sensitivity and specificity enable the quantification of androgens and consequently the characterization of the hormonal status. The aim of this study is the assessment of plasma androgens and androgen glucuronides, in the par excellence hormone-sensitive tissue of the breast, through the application of liquid chromatography-mass spectrometry (LC-MS). A simple and efficient fit-for-purpose method for the simultaneous identification and quantification of dehydroepiandrosterone sulfate (DHEAS), androstenedione (A4), androsterone glucuronide (ADTG) and androstane-3α, 17β-diol-17-glucuronide (3α-diol-17G) in human plasma was developed and validated. The presented method permits omission of derivatization, requires a single solid-phase extraction procedure and the chromatographic separation can be achieved on a single C18 analytical column, for all four analytes. The validated method was successfully applied for the analysis of 191 human plasma samples from postmenopausal women with benign breast disease (BBD), lobular neoplasia (LN), ductal carcinoma in situ and invasive ductal carcinoma (IDC). DHEAS plasma levels exhibited significant differences between LN, IDC and BBD patients (P < 0.05). Additionally, ADTG levels were significantly higher in patients with LN compared with those with BBD (P < 0.05).