Alterations in tissue microRNA after heat stress in the conscious rat: potential biomarkers of organ-specific injury.

BACKGROUND: Heat illness remains a significant cause of morbidity in susceptible populations. Recent research elucidating the cellular mechanism of heat stress leading to heat illness may provide information to develop better therapeutic interventions, risk assessment strategies, and early biomarkers of organ damage. microRNA (miRNA) are promising candidates for therapeutic targets and biomarkers for a variety of clinical conditions since there is the potential for high specificity for individual tissues and unique cellular functions. The objective of this study was to identify differentially expressed microRNAs and their putative mRNA targets in the heart, liver, kidney, and lung in rats at three time points: during heat stress (i.e., when core temperature reached 41.8 °C), or following a 24 or 48 h recovery period. RESULTS: Rats did not show histological evidence of tissue pathology until 48 h after heat stress, with 3 out of 6 rats showing cardiac inflammation and renal proteinosis at 48 h. The three rats with cardiac and renal pathology had 86, 7, 159, and 37 differentially expressed miRNA in the heart, liver, kidney, or lung, respectively compared to non-heat stressed control animals. During heat stress one differentially expressed miRNA was found in the liver and five in the lung, with no other modulated miRNA after 24 h or 48 h in animals with no evidence of organ injury. Pathway enrichment analysis revealed enrichment in functional pathways associated with heat stress, with the greatest effects observed in animals with histological evidence of cardiac and renal damage at 48 h. Inhibiting miR-21 in cultured cardiomyocytes increased the percent apoptotic cells five hours after heat stress from 70.9 ± 0.8 to 84.8 ± 2.2%. CONCLUSIONS: Global microRNA and transcriptomics analysis suggested that perturbed miRNA due to heat stress are involved in biological pathways related to organ injury, energy metabolism, the unfolded protein response, and cellular signaling. These miRNA may serve as biomarkers of organ injury and potential pharmacological targets for preventing heat illness or organ injury.

Utility of Serum miR-122, Liver Enzymes, and Hepatic Histopathology in Response to Hepatotoxicants in Sprague-Dawley Rats.

More than 80,000 chemicals are in commercial use worldwide. Hepatic metabolism to toxic intermediates is often a key mechanism leading to tissue damage and organ dysfunction. Effective treatment requires prompt detection of hepatotoxicity, ideally with rapid, minimally invasive diagnostic assays. In this study, archetypal histologic features of chemically induced hepatic injury were compared with clinical chemistries (including liver enzymes) and serum concentrations of microRNA-122 (miR-122, the processed form miR-122-5p), a biomarker of liver injury. The hepatotoxicants 4,4'-methylenedianiline (4,4'-MDA), allyl alcohol (AA), or carbon tetrachloride (CCl4) were orally administered to male Sprague-Dawley rats for 1, 5, 14, or 28 days to induce liver damage. Formalin-fixed, paraffin-embedded liver sections were evaluated histologically for inflammation, fibrosis, necrosis, and lipid accumulation. Liver enzymes were measured in serum, and serum miR-122 concentrations were assessed by quantitative polymerase chain reaction (qPCR). Histologic features of hepatic injury dose-dependently increased in both severity and frequency. Increases in liver enzymes and bilirubin were more pronounced in response to AA or 4,4'-MDA than to CCl4 at early time points. Elevated serum miR-122 levels in animals administered CCl4, AA, or 4,4'-MDA were more strongly associated with degree of hepatic histopathology than with dosage. Given this sensitive expression pattern postexposure, liver-specific miR-122 may improve the diagnostic accuracy of early hepatic injury.

Comparative Proteomic Analysis of Liver Steatosis and Fibrosis after Oral Hepatotoxicant Administration in Sprague-Dawley Rats.

The past decade has seen an increase in the development and clinical use of biomarkers associated with histological features of liver disease. Here, we conduct a comparative histological and global proteomics analysis to identify coregulated modules of proteins in the progression of hepatic steatosis or fibrosis. We orally administered the reference chemicals bromobenzene (BB) or 4,4'-methylenedianiline (4,4'-MDA) to male Sprague-Dawley rats for either 1 single administration or 5 consecutive daily doses. Livers were preserved for histopathology and global proteomics assessment. Analysis of liver sections confirmed a dose- and time-dependent increase in frequency and severity of histopathological features indicative of lipid accumulation after BB or fibrosis after 4,4'-MDA. BB administration resulted in a dose-dependent increase in the frequency and severity of inflammation and vacuolation. 4,4'-MDA administration resulted in a dose-dependent increase in the frequency and severity of periportal collagen accumulation and inflammation. Pathway analysis identified a time-dependent enrichment of biological processes associated with steatogenic or fibrogenic initiating events, cellular functions, and toxicological states. Differentially expressed protein modules were consistent with the observed histology, placing physiologically linked protein networks into context of the disease process. This study demonstrates the potential for protein modules to provide mechanistic links between initiating events and histopathological outcomes.

Influence of garlic (Allium sativum) on the pharmacokinetics of docetaxel.

PURPOSE: The herbal supplement garlic (Allium sativum) is commonly used by cancer patients. Preclinical studies have shown that allicin, a major component of garlic, may affect cytochrome P450 3A4 (CYP3A4) activity. This study examines the influence of garlic supplementation on the pharmacokinetics of docetaxel, a CYP3A4 substrate. EXPERIMENTAL DESIGN: Women with metastatic breast cancer were treated with docetaxel (30 mg/m(2)) given weekly for 3 of 4 weeks. Three days after the initial dose of docetaxel, patients received 600 mg of garlic twice daily for 12 consecutive days. Docetaxel pharmacokinetics were assessed during the first three administrations. RESULTS: In 10 evaluable patients, the mean baseline clearance of docetaxel was 30.8 L/h/m(2) [95% confidence intervals (95% CI), 16.7-44.9]. Coadministration of garlic reduced mean clearance of docetaxel to 23.7 L/h/m(2) (95% CI, 15.5-31.8) and 20.0 L/h/m(2) (95% CI, 13.3-26.7) on days 8 and 15, respectively (P = 0.17). Additional pharmacokinetic variables of docetaxel, including peak concentration (P = 0.79), area under the curve (P = 0.36), volume of distribution (P = 0.84), and half-life (P = 0.36), were also not statistically significantly different. The mean area under the curve ratio between day 15 and day 1 was 3.74 in three individuals with the CYP3A5*1A/*1A genotype (all African American) compared with 1.02 in six individuals with the CYP3A5*3C/*3C genotype (all Caucasian). CONCLUSIONS: This study indicates that garlic does not significantly affect the disposition of docetaxel. However, it cannot be excluded that garlic decreases the clearance of docetaxel in patients carrying a CYP3A5*1A allele.

Gene Expression Patterns Associated With Histopathology in Toxic Liver Fibrosis.

Toxic industrial chemicals induce liver injury, which is difficult to diagnose without invasive procedures. Identifying indicators of end organ injury can complement exposure-based assays and improve predictive power. A multiplexed approach was used to experimentally evaluate a panel of 67 genes predicted to be associated with the fibrosis pathology by computationally mining DrugMatrix, a publicly available repository of gene microarray data. Five-day oral gavage studies in male Sprague Dawley rats dosed with varying concentrations of 3 fibrogenic compounds (allyl alcohol, carbon tetrachloride, and 4,4'-methylenedianiline) and 2 nonfibrogenic compounds (bromobenzene and dexamethasone) were conducted. Fibrosis was definitively diagnosed by histopathology. The 67-plex gene panel accurately diagnosed fibrosis in both microarray and multiplexed-gene expression assays. Necrosis and inflammatory infiltration were comorbid with fibrosis. ANOVA with contrasts identified that 51 of the 67 predicted genes were significantly associated with the fibrosis phenotype, with 24 of these specific to fibrosis alone. The protein product of the gene most strongly correlated with the fibrosis phenotype PCOLCE (Procollagen C-Endopeptidase Enhancer) was dose-dependently elevated in plasma from animals administered fibrogenic chemicals (P < .05). Semiquantitative global mass spectrometry analysis of the plasma identified an additional 5 protein products of the gene panel which increased after fibrogenic toxicant administration: fibronectin, ceruloplasmin, vitronectin, insulin-like growth factor binding protein, and α2-macroglobulin. These results support the data mining approach for identifying gene and/or protein panels for assessing liver injury and may suggest bridging biomarkers for molecular mediators linked to histopathology.

Polymorphism in the hypoxia-inducible factor 1alpha gene may confer susceptibility to androgen-independent prostate cancer.

The hypoxia-inducible factor 1alpha (HIF-1alpha) plays a major role in cancer progression. The role of this transcription factor in prostate cancer development and its transition to a metastatic and androgen refractory state remains to be elucidated. Previous reports have identified the existence of single nucleotide polymorphisms (SNPs) in the oxygen-dependent degradation domain of the HIF-1alpha gene in renal cell carcinoma, head and neck squamous cell carcinoma, and androgen-independent prostate cancer (AIPC). Studies in prostate cancer, however, are variable and limited in the number of cases assessed. Herein we further investigate these SNPs, specifically C1772T (which results in an amino acid change from proline 582 to serine) and G1790A (alanine 588 to threonine). The frequency of these polymorphisms was evaluated in a population of individuals with metastatic AIPC and compared to a set of healthy control subjects. The distribution of HIF-1alpha genotypes for C1772T in 196 AIPC patients was 161 C/C (82.1%), 29 C/T (14.8%), and 6 T/T (3.1%). The genotype distribution in 196 controls was 179 C/C (91.3%), 14 C/T (7.1%), and 3 T/T (1.5%). Our results demonstrate a significant difference in genotype distribution between AIPC patients and control subjects only for the C1772T polymorphism (p = 0.024). The association of the incidence of the polymorphism with overall survival was determined to be not statistically significant (p = 0.93) by the Mantel-Haenszel (log-rank) test. These results suggest that the C1772T polymorphism in HIF-1alpha may confer susceptibility to AIPC and contribute to the progression or metastasis of this disease.

Exposure to cobalt causes transcriptomic and proteomic changes in two rat liver derived cell lines.

Cobalt is a transition group metal present in trace amounts in the human diet, but in larger doses it can be acutely toxic or cause adverse health effects in chronic exposures. Its use in many industrial processes and alloys worldwide presents opportunities for occupational exposures, including military personnel. While the toxic effects of cobalt have been widely studied, the exact mechanisms of toxicity remain unclear. In order to further elucidate these mechanisms and identify potential biomarkers of exposure or effect, we exposed two rat liver-derived cell lines, H4-II-E-C3 and MH1C1, to two concentrations of cobalt chloride. We examined changes in gene expression using DNA microarrays in both cell lines and examined changes in cytoplasmic protein abundance in MH1C1 cells using mass spectrometry. We chose to closely examine differentially expressed genes and proteins changing in abundance in both cell lines in order to remove cell line specific effects. We identified enriched pathways, networks, and biological functions using commercial bioinformatic tools and manual annotation. Many of the genes, proteins, and pathways modulated by exposure to cobalt appear to be due to an induction of a hypoxic-like response and oxidative stress. Genes that may be differentially expressed due to a hypoxic-like response are involved in Hif-1α signaling, glycolysis, gluconeogenesis, and other energy metabolism related processes. Gene expression changes linked to oxidative stress are also known to be involved in the NRF2-mediated response, protein degradation, and glutathione production. Using microarray and mass spectrometry analysis, we were able to identify modulated genes and proteins, further elucidate the mechanisms of toxicity of cobalt, and identify biomarkers of exposure and effect in vitro, thus providing targets for focused in vivo studies.

Exposure to nickel, chromium, or cadmium causes distinct changes in the gene expression patterns of a rat liver derived cell line.

Many heavy metals, including nickel (Ni), cadmium (Cd), and chromium (Cr) are toxic industrial chemicals with an exposure risk in both occupational and environmental settings that may cause harmful outcomes. While these substances are known to produce adverse health effects leading to disease or health problems, the detailed mechanisms remain unclear. To elucidate the processes involved in the toxicity of nickel, cadmium, and chromium at the molecular level and to perform a comparative analysis, H4-II-E-C3 rat liver-derived cell lines were treated with soluble salts of each metal using concentrations derived from viability assays, and gene expression patterns were determined with DNA microarrays. We identified both common and unique biological responses to exposure to the three metals. Nickel, cadmium, chromium all induced oxidative stress with both similar and unique genes and pathways responding to this stress. Although all three metals are known to be genotoxic, evidence for DNA damage in our study only exists in response to chromium. Nickel induced a hypoxic response as well as inducing genes involved in chromatin structure, perhaps by replacing iron in key proteins. Cadmium distinctly perturbed genes related to endoplasmic reticulum stress and invoked the unfolded protein response leading to apoptosis. With these studies, we have completed the first gene expression comparative analysis of nickel, cadmium, and chromium in H4-II-E-C3 cells.