Objective: Tamoxifen is currently used for the treatment of estrogen receptor-positive breast cancer patients, but acquired resistance to tamoxifen is a critical problem in breast cancer therapy. Suberoylanilide hydroxamic acid (SAHA) is a prototype of the newly developed HDAC inhibitor. The aim of this study is to investigate the anticancer effects of SAHA in tamoxifen-resistant MCF-7 (TAMR/MCF-7) cells.Methods: Cytotoxicity, apoptosis and autophagic cell death induced by SAHA were studied. A TAMR/MCF-7 cells xenograft model was established to investigate the inhibitory effect of SAHA on tumor growth in vivo.Results: SAHA inhibited the proliferation of TAMR/MCF-7 cells in a dose-dependent manner. SAHA significantly reduced the expression of HDAC1, 2, 3, 4 and 7 and increased acetylated histone H3 and H4. Although SAHA induced G2/M phase arrest of cell cycle, apoptotic cell death was very low, which is correlated with the slight change in the activation of caspases and PARP cleavage. Interestingly, expression of the autophagic cell death markers, LC3-II and beclin-1, was significantly increased in TAMR/MCF-7 cells treated with SAHA. Autophagic cell death induced by SAHA was confirmed by acridine orange staining and transmission electron microscopy (TEM) in TAMR/MCF-7 cells. In mice bearing the TAMR/MCF-7 cell xenografts, SAHA significantly reduced the tumor growth and weight, without apparent side effects.Conclusion: These results suggest that SAHA can induce caspase-independent autophagic cell death rather than apoptotic cell death in TAMR/MCF-7 cells. SAHA-mediated autophagic cell death is a promising new strategy to treatment of tamoxifen-resistant human breast cancer.

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The discovery of new biomarkers for early detection of drug-induced acute kidney injury (AKI) is clinically important. In this study, sensitive metabolomic biomarkers identified in the urine of rats were used to detect cisplatin-induced AKI. Cisplatin (10 mg kg(-1), i.p.) was administered to Sprague-Dawley rats, which were subsequently euthanized after 1, 3 or 5 days. In cisplatin-treated rats, mild histopathological alterations were noted at day 1, and these changes were severe at days 3 and 5. Blood urea nitrogen (BUN) and serum creatinine (SCr) levels were significantly increased at days 3 and 5. The levels of new urinary protein-based biomarkers, including kidney injury molecule-1 (KIM-1), glutathione S-transferase-α (GST-α), tissue inhibitor of metalloproteinase-1 (TIMP-1), vascular endothelial growth factor (VEGF), calbindin, clusterin, neutrophil, neutrophil gelatinase-associated lipocalin (NGAL), and osteopontin, were significantly elevated at days 3 and 5. Among urinary metabolites, trigonelline and 3-indoxylsulfate (3-IS) levels were significantly decreased in urine collected from cisplatin-treated rats prior to histological kidney damage. However, carbon tetrachloride (CCl4), a hepatotoxicant, did not affect these urinary biomarkers. Trigonelline is closely associated with GSH depletion and results in insufficient antioxidant capacity against cisplatin-induced AKI. The predominant cisplatin-induced AKI marker appeared to be reduced in urinary 3-IS levels. Because 3-IS is predominantly excreted via active secretion in proximal tubules, a decrease is indicative of tubular damage. Further, urinary excretion of 3-IS levels was markedly reduced in patients with AKI compared to normal subjects. The area under the curve receiver operating characteristics (AUC-ROC) for 3-IS was higher than for SCr, BUN, lactate dehydrogenase (LDH), total protein, and glucose. Therefore, low urinary or high serum 3-IS levels may be more useful for early detection of AKI than conventional biomarkers.

The regulated elimination of T cells serves to maintain normal immune function and prevents autoimmune responses. IL-2 family cytokines play an important role in controlling the survival of immature and mature T cells. These molecules activate the protein kinase, AKT/PKB. AKT has been shown to transduce an antiapoptotic signal in numerous cell types. In this study, we show that an active form of AKT can protect T cells from apoptosis following growth factor withdrawal and that IL-2 family cytokines can promote T cell survival by activating this kinase. We also provide evidence that AKT does not block death receptor-mediated killing of lymphocytes. These data suggest that AKT may serve as a common signaling element by which members of the IL-2 family of cytokines promote T cell survival.

In the manufacture of plastic containers, various materials such as additives (for example, plasticizers, stabilizers, antioxidants), polymers (for example, polystyrene [PS] for PC) presented in polymers, as additives (for example, phthalates for PVC) used in polymer manufacturing, and/or as contaminants from the polymers depending on physicochemical conditions such as temperature, UV light, pH, microwave, and mechanical stress. Some phthalates (for example, DEHP, DBP), styrene, or bisphenol have been suspected to have endocrine disrupting effects, but human toxicological effects of these compounds are very controversial. For these reasons, a comprehensive review on toxicological and risk assessment studies for these chemicals (phthalates, BPA, and styrene) was carried out to evaluate their safety in humans. On the basis of exposure estimates for the these chemicals and reference doses (RfDs), we calculated hazard index (HI = chronic daily intake/tolerable daily intake [TDI] or RfD). A HI of less than 1 suggests an exposure lower than the safety limit of the chemicals. We showed that the HI values of these chemicals were lower then 1, but there are one or several exceptions for di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), di-isodecyl phthalate (DIDP), and di-n-octyl phthalate (DnOP; for example, exposure via infant formula, packaged lunch, total exposure), where estimated their HI values are higher than 1, which suggests an exposure higher than the safety limits of the chemicals. However, the HI of BPA was 0.001-0.26 (3.57-1000 times lower than its safety limit), and the HI for styrene was 0.276 (3.62 times lower than its safety limit). In this article, we focused on recent issues concerning the endocrine-disrupting chemicals (EDCs) derived from plastic food containers or packaging. This review suggests that the use of plastic food containers might not exceed human safe limits n general with respect to endocrine disruptors aside from the exceptions of the phthalates mentioned earlier.

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The kidney is an important site of xenobiotic-induced toxicity. Because the traditional markers of renal injury indicate only severe renal damage, new biomarkers are needed for a more sensitive and reliable evaluation of renal toxicity. This study was designed to identify in vitro noninvasive biomarkers for efficient assessment of nephrotoxicity by using cisplatin as a model of nephrotoxic compounds. To this end, a comparative proteomic analysis of conditioned media from HK-2 human kidney epithelial cells treated with cisplatin was performed. Here, we identified pyruvate kinase M1/M2 isoform M2 (PKM2) and eukaryotic translation elongation factor 1 gamma (EF-1γ) as potential biomarker candidates for evaluation of nephrotoxicity. PKM2 and EF-1γ were increased by cisplatin in a kidney cell-specific manner, most likely due to cisplatin-induced apoptosis. The increase of PKM2 and EF-1γ levels in conditioned media was also observed in the presence of other nephrotoxic agents with different cytotoxic mechanisms such as CdCl2, HgCl2, and cyclosporine A. Rats treated with cisplatin, CdCl2, or HgCl2 presented increased levels of PKM2 and EF-1γ in the urine and kidney tissue. Taken together, this study identified two noninvasive biomarker candidates, PKM2 and EF-1γ, by comparative proteomic analysis. These new biomarkers may offer an alternative to traditional renal markers for efficient evaluation of nephrotoxicity.

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