Mechanism of Cell Death by Combined Treatment with an xCT Inhibitor and Paclitaxel: An Alternative Therapeutic Strategy for Patients with Ovarian Clear Cell Carcinoma.

Ovarian clear cell carcinoma (OCCC) is a rare subtype of epithelial ovarian carcinoma that responds poorly to chemotherapy. Glutathione (GSH) is a primary antioxidant, which protects cells against reactive oxygen species (ROS). High levels of GSH are related to chemotherapeutic resistance. The glutamine/cystine transporter xCT is essential for intracellular GSH synthesis. However, whether xCT inhibition can overcome the resistance to chemotherapeutic agents in OCCC remains unclear. This study demonstrated that combined treatment with paclitaxel (PTX) and the xCT inhibitor sulfasalazine (SAS) significantly enhanced cytotoxicity more than the individual drugs did in OCCC cells. Treatment with PTX and SAS induced apoptosis more effectively than did individual drug treatments in the cells with significant generation of ROS. Moreover, combined treatment with PTX and SAS induced ferroptosis in the cells with low expression of glutathione peroxidase (GPx4), high levels of intracellular iron and significant lipid ROS accumulation. Therefore, our findings provide valuable information that the xCT inhibitor might be a promising therapeutic target for drug-resistant OCCC. The strategy of combined administration of PTX and SAS can potentially be used to treat OCCC and help to develop novel therapeutic methods.

Early menopause and a low body mass index are associated with an increased risk of coronary heart disease in Japanese women.

OBJECTIVE: The primary objective was to investigate the association between early menopause and cardiovascular disease (CVD) prevalence in Japanese women. The secondary objective was to ascertain the association with CVD risk factors. METHODS: In this cross-sectional study, 7,239 naturally menopausal women from the Yamagata Cohort Study who completed an annual health visit and questionnaire between 2009 and 2015 were divided into three groups according to their age at menopause (women experiencing menopause at <45, 45-49 y, and ≥ 50 y). The diagnosis of coronary heart disease (CHD) and stroke were made by self-report, while hypertension, hyperlipidemia, and diabetes mellitus, were diagnosed by vital signs and laboratory parameters. Logistic regression analysis was used to estimate the associations between age at menopause and CVD prevalence and CVD risk factors. RESULTS: A total of 354 (4.9%) and 156 (2.2%) women reported a history of CHD and stroke, respectively. Women experiencing menopause at <45 years had a higher prevalence of CHD than those experiencing menopause at ≥50 years (OR 1.77, 95% CI 1.07-2.90; P = 0.023). Stroke, hypertension, diabetes mellitus, and hyperlipidemia were equally prevalent among the three groups. Significant interactions were observed between age at menopause and body mass index (BMI) (P = 0.025) and parity (P = 0.025). Among those with a BMI < 18.5 or parity ≥2, women experiencing menopause at <45 years had a significantly higher prevalence of CHD than those experiencing menopause at ≥50 years. CONCLUSION: Early menopause and low BMI were associated with CHD in Japanese women.

Oxidative Stress in the Visceral Fat Is Elevated in Postmenopausal Women with Gynecologic Cancer.

OBJECTIVES: This study aimed to evaluate differences in oxidative stress of visceral fat between premenopausal and postmenopausal women and clarify the antioxidant effect of estrogen on adipocytes. MATERIALS AND METHODS: Abdominal subcutaneous and omental visceral adipose tissues were obtained from 38 patients who underwent gynecological surgery. We measured the sizes of the adipocytes and evaluated the lipid peroxidation levels in the adipose tissues. We investigated whether estrogen inhibited the intracellular reactive oxygen species (ROS) production that was induced by hydrogen peroxide (H2O2) in 3T3-L1 adipocytes. RESULTS: The visceral adipocytes were 1162.4 µm2 and 1881.9 µm2 in premenopausal and postmenopausal women, respectively; hence they were significantly larger in the latter (p < 0.05). The lipid peroxidation levels were 46.7 nmoL/mg protein in premenopausal women and 99.6 nmoL/mg protein in postmenopausal women; hence the lipid peroxidation levels were significantly higher in the latter (p < 0.05). Estradiol (E2) significantly reduced the intracellular ROS levels that were induced by H2O2 in 3T3-L1 adipocytes (p < 0.01). We determined that E2 significantly increased the expression of nuclear factor erythroid 2-related factor 2 (NRF2)-dependent antioxidant genes, heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), and the glutamate-cysteine ligase (GCL) modifier subunit genes, in 3T3-L1 adipocytes (p < 0.01). CONCLUSION: Oxidative stress in the visceral fat is higher in postmenopausal women. The expression of the antioxidant genes HO-1, NQO1, and GCL was upregulated by estrogen in 3T3-L1 adipocytes. Hence, estrogen may act as an antioxidant in the adipose tissues of premenopausal women.

[Sex hormones and physiological function].

Sex hormones as estrogen, testosterone, dehydroepiandrosterone decline with age. Especially in women, bioavailable estrogen level rapidly decreases around the menopause. Estrogen acts against arteriosclerosis to vascular endothelial cells and vascular smooth muscle cells. The lack of estrogen with menopause accelerates arteriosclerosis that is the leading cause of cardiovascular diseases. The adipose distribution shifts from gluteo-femoral to abdominal depots after menopause, and it is well known that visceral obesity induce metabolic syndrome, which is also high risk state for cardiovascular disease. Estrogen replacement therapy may reduce the cardiovascular risk, and we should pay attention to the starting age of women who undergo hormone therapy.

Differences in the fatty acid metabolism of visceral adipose tissue in postmenopausal women.

OBJECTIVE: Visceral fat accumulation and metabolic syndrome incidence among women increase after menopause; therefore, fat metabolic changes and fat redistribution may occur according to menstrual status. The aim of our study was to clarify differences in subcutaneous and visceral adipose tissue metabolism between premenopausal and postmenopausal women, using metabolomics. METHODS: Thirty-nine (16 premenopausal and 23 postmenopausal) women were recruited through elective gynecologic surgery, and both subcutaneous and visceral adipose tissues were collected during surgical operation. Metabolite profiling of adipose tissue was performed by capillary electrophoresis with electrospray ionization time-of-flight mass spectrometry. RESULTS: Sedoheptulose 7-phosphate, a midproduct of the pentose phosphate pathway, was significantly higher (P < 0.05) in visceral adipose tissues of premenopausal women. Dihydroxyacetone phosphate and fructose-1,6-biphosphate, midproducts of glycolysis, were significantly higher (P < 0.05) in subcutaneous adipose tissues of postmenopausal women. The concentrations of fatty acid metabolites-heptanoate (C7:0; premenopausal vs postmenopausal, 4.07 [0.72] vs 2.64 [0.28] nmol/g), octanoate (C8:0; 3.52 [0.29] vs 5.20 [0.29] nmol/g), and pelargonate (C9:0; 8.03 [0.49] vs 10.66 [0.44] nmol/g)-in the visceral fat (but not in subcutaneous fat) of postmenopausal women were significantly higher (P < 0.05) than those in the visceral fat of premenopausal women. CONCLUSIONS: Fatty acid metabolites increase in visceral fat (but not in subcutaneous fat) after menopause. The change in fatty acid metabolism in visceral adipose tissues might be related to metabolic syndrome in postmenopausal women.

Association of estrogen with glucocorticoid levels in visceral fat in postmenopausal women.

OBJECTIVE: The aim of this study is to clarify the association between estrogen and glucocorticoid levels in adipose tissues of premenopausal and postmenopausal women. METHODS: Forty (15 premenopausal and 25 postmenopausal) women aged 22 to 79 years were recruited through elective gynecological surgical operation, and both subcutaneous and visceral fat were collected during the surgical operation. Messenger RNA (mRNA) expressions of 11ß hydroxysteroid dehydrogenase type 1 (HSD1), which catalyzes cortisone to cortisol, and 17ß-HSD1 and 17ß hydroxysteroid dehydrogenase type 2 (HSD2), which catalyze the interconversion of estrone (E1) and estradiol (E2), were measured by real-time reverse transcription polymerase chain reaction. The levels of E1, E2, cortisol, and cortisone in adipose tissues were measured by liquid chromatography tandem mass spectrometry. RESULTS: The visceral fat area was significantly increased (P < 0.01) in postmenopausal women compared with that in premenopausal women. The cortisol/cortisone ratio (P < 0.01) and the expression of 11ß-HSD1 mRNA (P < 0.001) in visceral fat, but not in subcutaneous fat, in postmenopausal women were significantly higher than those in premenopausal women. There was a significant correlation (r = 0.69, P < 0.05) between the E1/E2 ratio of visceral fat and body mass index in postmenopausal women. A significant correlation (r = 0.54, P < 0.05) between the cortisol/cortisone ratio and the E1/E2 ratio of visceral fat was observed in postmenopausal women. CONCLUSIONS: The expression of 11ß-HSD1 mRNA in visceral fat increases in postmenopausal women, and the E1/E2 ratio in visceral fat may be associated with local glucocorticoid levels after menopause.

Estrogen induces neurite outgrowth via Rho family GTPases in neuroblastoma cells.

Estrogen (E2) has direct in vivo and in vitro effects, such as inducing neurite outgrowth, on neurons. We investigated the morphological changes and intracellular signaling pathway induced by E2 in neuroblastoma (SH-SY5Y) cells. The effect of medroxyprogesterone acetate (MPA) or progesterone (P4) on the E2-induced neurite outgrowth was also examined using SH-SY5Y cells. Neurite outgrowth was induced by E2 in association with the phosphorylation of Akt, and these effects of E2 were abolished by MPA but not by P4. Progesterone receptor antagonist RU486 blocked the inhibitory effects of MPA. Estrogen receptor antagonist ICI 182,780 and phosphatidylinositol 3-kinase inhibitor LY294002 inhibited the E2-induced neurite outgrowth. Because the Rho family of small GTPases has been shown to be involved in the regulation of neurite outgrowth, we examined the cross-talk among Rac1, Cdc42 and RhoA in the E2-induced neurite outgrowth. E2 immediately increased the Rac1 and Cdc42 activity and decreased the RhoA activity. E2-induced neurite outgrowth was attenuated in cells expressing dominant-negative mutants for Rac1 or Cdc42. These results suggest that regulation of Rho family GTPase activity by E2 is important for the neurite outgrowth in neuroblastoma cells, and that MPA may have an antagonistic effect against E2.