Characterizing the mechanism of thiazolidinedione-induced hepatotoxicity: An in vitro model in mitochondria.

OBJECTIVE: To characterize the mechanism of action of thiazolidinedione (TZD)-induced liver mitochondrial toxicity caused by troglitazone, rosiglitazone, and pioglitazone in HepaRG cells. METHODS: Human hepatoma cells (HepaRG) were treated with troglitazone, rosiglitazone, or pioglitazone (12.5, 25, and 50µM) for 48h. The Seahorse Biosciences XF24 Flux Analyzer was used to measure mitochondrial oxygen consumption. The effect of TZDs on reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were detected by flow cytometry. The mitochondrial ultrastructure of HepaRG cells was observed under a transmission electrical microscope (TEM). mtDNA content was evaluated by real-time PCR, and ATP content and mitochondrial respiratory chain (MRC) complex I, II, III, IV activity were measured via chemiluminescence. Results were considered statistically significant at p<0.05. RESULTS: Among the three drugs, troglitazone exhibited the highest potency, followed by rosiglitazone, and then pioglitazone. The TZDs caused varying degrees of mitochondrial respiratory function disorders including decreases in oxygen consumption, MRC activity, and ATP level, and an elevation in ROS level. TZD treatment resulted in mtDNA content decline, reduction in MMP, and alterations of mitochondrial structure. CONCLUSION: All investigated TZDs show a certain degree of mitochondrial toxicity, with troglitazone exhibiting the highest potency. The underlying mechanism of TZD-induced hepatotoxicity may be associated with alterations in mitochondrial respiratory function disorders, oxidative stress, and changes in membrane permeability. These parameters may be used early in drug development to further optimize risk:benefit profiles.

Studies on the characteristics and mechanisms of testicular toxicity induced by Hydroxyurea.

OBJECTIVE: Apoptosis plays a dominant role in both spontaneous spermatogenesis and germ cell death. This study was aimed to investigate the functions of related genes in testicular germ cell death induced by Hydroxyurea (HU). METHOD: Wild-type (WT) and FasL transgenic (TG) DBA/C57BL mice were intraperitoneal injected with 400 mg/kg HU. Twelve hours later, testes were collected. Histomorphology of testis was observed by staining with Periodic Acid Schiff (PAS). Apoptosis was assessed by TUNEL assay. mRNA and protein levels of related genes were evaluated by quantitative RT-PCR and Western blot, respectively. RESULTS: The 2 × 2 factorial design comparative experiments between the WT and TG mice showed that the TG mice exhibited a higher basal apoptotic index. The basal mRNA levels of Fas and FasL and protein levels of Fas, FasL, Caspase-3, Caspase-8 and Caspase-9 in the TG mice were also higher than that in the WT mice. Twelve hours after injection of HU, the testicular tubules exhibited no significantly morphological changes but apoptosis index remarkably increased in both the WT and TG mice, with the latter having the higher amplitude. Although, HU up-regulated the mRNA of apoptosis-related genes, such as Fas and FasL, in both the TG and WT mice, the increased amplitude was more obvious in the TG mice. By Western blot analysis, apoptosis-related proteins Fas, FasL Caspase-3, Caspase-8 and Caspase-9 were significantly increased in both the WT and TG mice, with the TG mice exhibiting a greater up-regulation. CONCLUSION: Germ cell apoptosis induced by the HU treatment may be related to the FasL-mediated signal transduction pathway.

MiR-96-5p inhibition induces cell apoptosis in gastric adenocarcinoma.

BACKGROUND: Gastric adenocarcinoma (GAC) mortality rates have remained relatively changed over the past 30 years, and it continues to be one of the leading causes of cancer-related death. AIM: To search for novel miRNAs related to GAC prognosis and further investigate the effect of miR-96-5p on MGC-803 cells. METHODS: The miRNA expression profile data of GAC based on The Cancer Genome Atlas were obtained and used to screen differently expressed miRNAs (DEMs) and DEMs related to GAC prognosis. Then, the expression of DEMs related to GAC prognosis was identified in GAC tumor samples and adjacent normal samples by qRT-PCR. The target gene, ZDHHC5, of miR-96-5p was predicted using TargetScan, miRTarBase, and miRDB databases and confirmed by luciferase reporter assay. Furthermore, MGC-803 cells were transfected with inhibitor NC, miR-96-5p inhibitor, si-ZDHHC5, or miR-96-5p inhibitor + si-ZDHHC5, and then cell apoptosis was detected by flow cytometry. The expression of ZDHHC5, Bcl-2, and COX-2 was detected using western blotting. RESULTS: A total of 299 DEMs and 35 DEMs related to GAC prognosis were screened based on The Cancer Genome Atlas. Then compared with adjacent normal samples, the levels of miR-96-5p, miR-222-5p, and miR-652-5p were remarkably increased, while miR-125-5p, miR-145-3p, and miR-379-3p levels were reduced in GAC tumor samples (P < 0.01), which were consistent with bioinformatics analysis. Furthermore, ZDHHC5 was defined as a direct target gene of miR-96-5p. miR-96-5p inhibition increased the number of apoptotic cells as well as promoted the expression of ZDHHC5, Bcl-2, and COX-2 in MGC-803 cells (P < 0.01). After ZDHHC5 inhibition, the number of apoptotic cells and the expression of ZDHHC5, Bcl-2, and COX-2 were reduced. The addition of an miR-96-5p inhibitor partly reversed these effects (P < 0.01). CONCLUSION: Our findings identified six miRNAs related to GAC prognosis and suggested that downregulated miR-96-5p might induce cell apoptosis via upregulating ZDHHC5 expression in MGC-803 cells.

NMR-spectroscopy-based metabonomic approach to the analysis of Bay41-4109, a novel anti-HBV compound, induced hepatotoxicity in rats.

An integrated metabonomics study using high-resolution (1)H nuclear magnetic resonance (NMR) spectroscopy has been applied to investigate the biochemical composition of urine, serum, liver tissue aqueous extracts (acetonitrile/water) and liver tissue lipidic extracts (chloroform/methanol) obtained from control and Bay41-4109 treated rats (10, 50, 400mg.kg(-1).d(-1) for 5 days, i.g.). Principal components analysis was used to visualize similarities and differences in biochemical profiles. The results showed the effects induced by Bay41-4109 at 400mg.kg(-1).d(-1) are different from those induced at 10, 50mg.kg(-1).d(-1). The biochemical profiles of 400mg.kg(-1).d(-1) group might reflect the hepatotoxicity of Bay41-4109 more exactly. The elevation in the level of 3-HB, lactate, 2-hydroxy-acetol and d-glucose was found in the urine, and the levels of VLDL/LDL(CH(2))(n), VLDL/LDL-CH(3), 2-oxo-3-methyl-n-valerate, 3-HB, lactate, acetate, taurine, 2-hydroxy-isovalerate in serum were increased significantly in 400mg.kg(-1).d(-1) group. The predominant changes identified in liver tissue aqueous extracts included an increase in the signal intensities of lactate, 3-amino-isovalerate, pyruvate, choline, trimethylamine-N-oxide (TMAO) and a reduction in the intensities of taurine, hippurate and d-glucose. In liver tissue chloroform/methanol extracts, there was a remarkably increase in many of the lipid signals including the triglyceride terminal methyl, methylene groups, and CH(2)CO, N(+)(CH(3))(3), CH(2)OPO(2), CH(2)OCOR. These observations all provide evidence that fatty acid metabolism disorder and mitochondrial inability might contribute to the hepatotoxicity of Bay41-4109. The application of (1)H NMR spectroscopy to an array of biological samples comprising urine, serum and liver tissue extracts yields new insight into the hepatotoxicity of xenobiotics.