Potential role of heme metabolism in the inducible expression of heme oxygenase-1.

BACKGROUND: The degradation of heme significantly contributes to cytoprotective effects against oxidative stress and inflammation. The enzyme heme oxygenase-1 (HO-1), involved in the degradation of heme, forms carbon monoxide (CO), ferrous iron, and bilirubin in conjunction with biliverdin reductase, and is induced by various stimuli including oxidative stress and heavy metals. We examined the involvement of heme metabolism in the induction of HO-1 by the inducers sulforaphane and sodium arsenite. METHODS: We examined the expression of HO-1 in sulforaphane-, sodium arsenite- and CORM3-treated HEK293T cells, by measuring the transcriptional activity and levels of mRNA and protein. RESULTS: The blockade of heme biosynthesis by succinylacetone and N-methyl protoporphyrin, which are inhibitors of heme biosynthesis, markedly decreased the induction of HO-1. The knockdown of the first enzyme in the biosynthesis of heme, 5-aminolevulinic acid synthase, also decreased the induction of HO-1. The cessation of HO-1 induction occurred at the transcriptional and translational levels, and was mediated by the activation of the heme-binding transcriptional repressor Bach1 and translational factor HRI. CO appeared to improve the expression of HO-1 at the transcriptional and translational levels. CONCLUSIONS: We demonstrated the importance of heme metabolism in the stress-inducible expression of HO-1, and also that heme and its degradation products are protective factors for self-defense responses. GENERAL SIGNIFICANCE: The key role of heme metabolism in the stress-inducible expression of HO-1 may promote further studies on heme and its degradation products as protective factors of cellular stresses and iron homeostasis in specialized cells, organs, and whole animal systems.

NEDD9 crucially regulates TGF-ß-triggered epithelial-mesenchymal transition and cell invasion in prostate cancer cells: involvement in cancer progressiveness.

BACKGROUND: NEDD9 is one of the Crk-associated substrate (Cas) family proteins that mediate downstream signaling processes including cytoskeletal organization, cell-cycle and tumorigenesis. While NEDD9 plays a crucial role in epithelial-mesenchymal transition (EMT), the functional mechanism underlying NEDD9-mediated EMT in prostate cancer (PCa) remains uncertain. METHODS: The expression levels of NEDD9 and its downstream molecules in PC-3, LNCaP, and VCaP cells exposed to transforming growth factor-ß (TGF-ß) were determined by western blotting. The invasion of these cells with ectopic overexpression of NEDD9 or silencing of NEDD9 expression was measured by transwell invasion assay. Human tissue samples comprising 45 PCa specimens and ten specimens of normal prostatic tissue were used for immunohistochemical (IHC) analysis of NEDD9 expression. RESULTS: Both NEDD9 and its downstream signaling molecules associated with EMT were strongly induced by TGF-ß in PCa cells. PC-3 cells with stable overexpression of NEDD9 had a mesenchymal phenotype and significantly enhanced cell invasion, despite their decreased cell proliferation. Knockdown of endogenous NEDD9 expression completely diminished TGF-ß-triggered tumor invasion in several PCa cell lines. The IHC data revealed a significant positive correlation between the NEDD9 staining score and tumor aggressiveness (e.g., Gleason grade, serum PSA level). The NEDD9 staining score in primary PCa with bone metastasis was significantly higher than that in PCa without metastasis. CONCLUSIONS: NEDD9 may be a key mediator involved in TGF-ß-mediated EMT and cell motility in PCa cells and a novel target in the treatment of metastatic PCa and prevention of spread of localized PCa cells to other organs.

Toxicological aspects of cadmium and occupational health activities to prevent workplace exposure in Japan: A narrative review.

Chemicals are an essential part of modern manufacture processes. Their use must be managed with great attention in occupational settings to avoid serious detrimental effects to the health of employees. For example, cadmium compounds are indispensable for the production of nickel-cadmium rechargeable batteries or as chemical stabilizer in plastics. It is an exceptionally toxic heavy metal and personnel exposed to cadmium in the workplace meet with potential health risks that can lead to the development of kidney, skeletal and respiratory disorders. In consequence, proactive and systematical development of occupational hygiene and health activities are necessary to reduce chemical exposure to cadmium in the workplace. This review describes the known facts of cadmium toxicity, the biological effects of cadmium exposure, possible regulation measures to prevent occupational cadmium exposure in three industrial health management systems and discusses future cooperation programs in these systems, proactive safety activities and occupational safety and health management strategies.

[Comparison of diagnostic criteria for the metabolic syndrome among Japanese university faculty].

OBJECTIVES: Diagnostic criteria for the metabolic syndrome (Mets) in Japan have been set by the Medical Committee of the Japanese Association of Medical Sciences (Med), the National Health and Nutrition Examination Survey (Nat), specific health checkups (Ckup), and second medical examination by Worker's Accident Compensation Insurance System (Wor). The purpose of this study was to compare classification of the metabolic syndrome by different organizational criteria and to investigate underlying differences. METHODS: All faculty members of a university in Osaka, Japan, underwent mandatory health checkups in September 2008. The demographic distribution included 769 males (mean age, 49 +/- 12 years) and 415 females (mean age, 43 +/- 10 years). Using the Med, Nat, Ckup and Wor criteria, individuals were assessed for the MetS and pre-metabolic syndrome (pre-Mets), strongly suspected metabolic syndrome (S-Mets) and assumed pre-metabolic syndrome (A-pre-Mets), as well as a positive support level (PSL) and a motivational support level (MSL). All faculty members were categorized into a morbid group (Mets, S-Mets, PSL, and FB) or a pre-morbid group (pre-Mets, A-pre-Mets, and MSL) based on medical data and smoking habits. The incidence of morbid and pre-morbid individuals was compared across the four criteria and analyzed based on gender and age (under 40 and 40 or over). RESULTS: Male incidences for the morbid and pre-morbid classifications were 17% and 20% with Med, 9% and 23% with Nat, 27% and 14% with Ckup, and 1.4% and 0% with Wor. There were significant differences across criteria sets in both the morbid and pre-morbid groups, with significantly greater numbers of males than females, and higher prevalences in those aged 40 or over than in their younger counterparts. Males aged under 40 classified into the pre-morbid group comprised 18% in Med, 16% in Nat, and 13% in Ckup. CONCLUSION: The different disease incidences found between Med and Ckup data in males aged 40 or over might be attributed to varying criteria for blood glucose levels, while Wor data may be influenced by the higher level of blood pressure set as a criterion with this approach. It will be important to continuously validate currently established criteria to identify the actual prevalence of MetS in Japan. Furthermore, incorporation of waist circumference and BMI for females, and a positive approach for young males, may be critical for future developments.

Phospholipase C-dependent Ca2+-sensing pathways leading to endocytosis and inhibition of the plasma membrane vacuolar H+-ATPase in osteoclasts.

In osteoclasts, elevation of extracellular Ca2+ is an endogenous signal that inhibits bone resorption. We recently found that an elevation of extracellular Ca2+ decreased proton extrusion through the plasma membrane vacuolar H+-ATPase (V-ATPase) rapidly. In this study we investigated mechanisms underlying this early Ca2+-sensing response, particularly in reference to the activity of the plasma membrane V-ATPase and to membrane retrieval. Whole cell clamp recordings allowed us to measure the V-ATPase currents and the cell capacitance (C(m)) simultaneously. C(m) is a measure of cell surface. Extracellular Ca2+ (2.5-40 mM) decreased C(m) and the V-ATPase current simultaneously. The decreased C(m), together with the enhanced uptake of a lipophilic dye (FM1-43), indicated that Ca2+ facilitated endocytosis. The endocytosis was blocked by dynamin inhibitors (dynasore and dynamin-inhibitory peptide), by small interfering RNA (siRNA) targeting for dynanmin-2 and also by bafilomycin A(1), a blocker of V-ATPases. The extracellular Ca2+-induced endocytosis and inhibition of the V-ATPase current were diminished by a phospholipase C inhibitor (U73122) and siRNA targeting for phospholipase C gamma2 subunit. Holding the cytosolic Ca2+ at either high (0.5-5 microM) or low levels or inhibiting calmodulin by an inhibitor (W7) or an antibody (anti-CaM) decreased the stimulated endocytosis and the inhibition of the V-ATPase current. These data suggest that extracellular Ca2+ facilitated dynamin- and V-ATPase-dependent endocytosis in association with an inhibition of the plasma membrane V-ATPase. Phospholipase C, cytosolic Ca2+, and calmodulin were involved in the signaling pathways. Membrane retrieval and the plasma membrane V-ATPase activity may cooperate during the early phase of Ca2+-sensing response in osteoclasts.

Indirect antitumor effects of bisphosphonates on prostatic LNCaP cells co-cultured with bone cells.

Bisphosphonates are strong inhibitors of osteoclastic bone resorption in both benign and malignant bone diseases. The nitrogen-containing bisphosphonates (N-BPs) have strong cytotoxicity via inhibition of protein prenylation in the mevalonate pathway, and also demonstrate direct cytostatic and proapoptotic effects on prostate cancer cells. We confirmed the usefulness of a co-culture system comprised of prostatic LNCaP cells, ST2 cells (mouse-derived osteoblasts) and MLC-6 cells (mouse-derived osteoclasts) in vitro. N-BPs (pamidronate and zoledronic acid) inhibited both androgen receptor transactivation and tumor cell proliferation by suppressing the activities of both osteoclasts and osteoblasts with low-dose exposure. This indirect inhibition of prostate cancer cells via bone cells could be beneficial in treating prostate cancer patients with bone metastases.

Distribution, elimination, and renal effects of single oral doses of europium in rats.

Single doses of europium (III) chloride hexahydrate were orally administered to several groups of rats. Cumulative urine samples were taken at 0-24 h, and blood samples were drawn after 24-h administration. The europium concentration was determined in these samples by inductively coupled plasma atomic emission spectroscopy. The volume, creatinine, ß-2-microglobulin, and N-acetyl-ß-D-glucosaminidase were measured in the urine samples to evaluate possible europium-induced renal effects. The blood samples showed low europium distribution, with an average of 77.5 µg/L for all groups. Although the urinary concentration and excretion showed dose-dependent increases, the percentage of europium excreted showed a dose-dependent decrease, with an average of 0.31% in all groups. The administration of europium resulted in a significant decrease of creatinine and a significant increase of urinary volume, N-acetyl-ß-D-glucosaminidase, and ß-2-microglobulin. Rare earth elements, including europium, are believed to form colloidal conjugates that deposit in the reticuloendothelial system and glomeruli. This specific reaction may contribute to low europium bioavailability and renal function disturbances. Despite low bioavailability, the high performance of the analytical method for determination of europium makes the blood and urine sampling suitable tools for monitoring of exposure to this element. The results presented in this study will be of great importance in future studies on the health impacts of rare earth elements.

Toxicokinetics and metabolism deteriorated by acute nephrotoxicity after a single intravenous injection of hydrofluoric acid in rats.

OBJECTIVES: This study was designed to investigate the early dynamic state of hydrofluoric acid (HFA) in blood and urine as a model of accidental occupational exposure to a subtoxic dose of HFA. It was also aimed at determining the relationship between the kinetics and harmful effects of HFA on the kidney. METHODS: Rats received a single intravenous injection of HFA (3.2, 6.4, or 9.6 (LD(5)) mg/kg) or saline. The volume of each injection was 1 ml and the concentrations of HFA were 0.1, 0.2, and 0.3%, respectively. Ionized fluoride (F) was measured for the biological monitoring of HFA. Serum F concentrations were determined at 0, 5, 10, 30, 60, 120, and 300 min. Pharmacokinetic parameters were calculated with two-compartment modeling. Urine was directly collected from bladder for 300 min to determine the extent of the renal damage. RESULTS: AUC(0→300) values were significantly higher in the 9.6 mg/kg group than in the 3.2 and 6.4 groups. The total body clearance, V(1), V(2) and V(ss) were significantly lower in the 6.4 and 9.6 mg/kg groups than in the 3.2 mg/kg group. These results indicate that HFA was retained in blood. This could be a result of renal dysfunction. NAG/Cr and glucose excretion amount in urine were increased, and the clearance rate of F, urine volume and excretion amounts of electrolytes were decreased in the 9.6 mg/kg group compared with the saline group. These findings indicate renal tubular damage and a decrease in the amount of excretion of HFA from the kidney. CONCLUSIONS: We consider that acute nephrotoxicity of HFA caused renal injury, and the harmful effects of HFA were subsequently aggravated by its delayed metabolism.

Urinary scandium as predictor of exposure: effects of scandium chloride hexahydrate on renal function in rats.

Some of the rare earth elements such as Sc are believed to be non-toxic and, at present, are widely utilized for the replacement of toxic heavy metals in technological applications, but they are not entirely free of toxicity, with hidden potential health risks. In this animal experiment, we report the urinary scandium (Sc) excretion rate and nephrotoxiciy in male Wistar rats. For this purpose, the rats were given a single dose of a solution of scandium chloride by intraperitoneal injection. The Sc excretion (U-Sc) was determined in 24-h urine samples by inductively coupled plasma-argon emission spectrometry along with the Sc nephrotoxicity, urine volume (UV), creatinine (Crt), beta-2-microglobulin (beta2-MG) and N-acetyl-beta-D-glucosaminidase (NAG). A dose-dependent Sc excretion of 0.0063% (r = 0.97) via 24-h urine was confirmed. The administration of Sc induced a significant decrease of UV and Crt and a significant increase of NAG and beta2-MG. These results suggest that U-Sc can be a useful tool for monitoring Sc exposure. The formation of Sc colloidal conjugates that deposit in glomeruli may be the cause of a reduction of the glomerular filtration rate. We propose that the analytical method and results described in this study will be of great importance for future toxicological studies on Sc exposure.