Characterization of acute biliary hyperplasia in Fisher 344 rats administered the indole-3-carbinol analog, NSC-743380.

NSC-743380 (1-[(3-chlorophenyl)-methyl]-1H-indole-3-carbinol) is in early stages of development as an anticancer agent. Two metabolites reflect sequential conversion of the carbinol functionality to a carboxaldehyde and the major metabolite, 1-[(3-chlorophenyl)-methyl]-1H-indole-3-carboxylic acid. In an exploratory toxicity study in rats, NSC-743380 induced elevations in liver-associated serum enzymes and biliary hyperplasia.

Comparative uterotrophic effects of endoxifen and tamoxifen in ovariectomized Sprague-Dawley rats.

Endoxifen (4-hydroxy-N-desmethyl-tamoxifen), one of the major active metabolites of tamoxifen, has substantially greater estrogen antagonist properties and antiproliferative effects in breast tumor cells than tamoxifen, a mixed estrogen agonist/antagonist. An associated risk of endometrial cancer and hyperplasia has been linked to the estrogen agonist properties of tamoxifen. We evaluated endoxifen using a classic uterotrophic effects method.

Identification and elucidation of the biology of adverse events: the challenges of safety assessment and translational medicine.

There has been an explosion of technology-enabled scientific insight into the basic biology of the causes of adverse events. This has been driven, in part, by the development of the various "omics" tools (e.g.

Renal biomarker qualification submission: a dialog between the FDA-EMEA and Predictive Safety Testing Consortium.

The first formal qualification of safety biomarkers for regulatory decision making marks a milestone in the application of biomarkers to drug development. Following submission of drug toxicity studies and analyses of biomarker performance to the Food and Drug Administration (FDA) and European Medicines Agency (EMEA) by the Predictive Safety Testing Consortium's (PSTC) Nephrotoxicity Working Group, seven renal safety biomarkers have been qualified for limited use in nonclinical and clinical drug development to help guide safety assessments. This was a pilot process, and the experience gained will both facilitate better understanding of how the qualification process will probably evolve and clarify the minimal requirements necessary to evaluate the performance of biomarkers of organ injury within specific contexts.

Qualification of cardiac troponin I concentration in mouse serum using isoproterenol and implementation in pharmacology studies to accelerate drug development.

Cardiac troponin I is a useful biomarker of myocardial injury, but its use in mice and application to early drug discovery are not well described. The authors investigated the relationship between cTnI concentration in serum and histologic lesions in heart tissue from mice treated with isoproterenol (ISO). Cardiac TnI concentrations in serum increased in a dose-dependant manner and remained increased twenty-four to forty-eight hours after a single administration of isoproterenol.

Chronic microcystin exposure induces hepatocyte proliferation with increased expression of mitotic and cyclin-associated genes in P53-deficient mice.

Homozygous p53 deficient knockout mice were used to assess the role of p53 in tumor promotion by the protein phosphatase inhibitor and hepatic tumor promoter microcystin-LR (MCLR). More than 50% of human cancers bear mutations in the p53 gene, and in particular, p53 tumor suppressor gene mutations have been shown to play a major role in hepatocarcinogenesis. Trp53 homozygous (inactivated p53) and age-matched wild-type control mice were assigned to vehicle or MCLR-treated groups.

Hepatic gene expression changes in mice associated with prolonged sublethal microcystin exposure.

Microcystin-LR (MCLR) is an acute hepatotoxicant and suspected carcinogen. Previous chronic studies have individually described hepatic morphologic changes, or alterations in the cytoskeleton, cell signaling or redox pathways. The objective of this study was to characterize chronic effects of MCLR in wild-type mice utilizing gene array analysis, morphology, and plasma chemistries.

Proteomic analysis of rat liver phosphoproteins after treatment with protein kinase inhibitor H89 (N-(2-[p-bromocinnamylamino-]ethyl)-5-isoquinolinesulfonamide).

Therapeutic strategies focused on kinase inhibition rely heavily on surrogate measures of kinase inhibition obtained from in vitro assay systems. There is a need to develop methodology that will facilitate measurement of kinase inhibitor activity or specificity in tissue samples from whole animals treated with these compounds. Many of the current methods are limited by the use of antibodies, many of which do not cross-react between several species.

Tsc2 expression increases the susceptibility of renal tumor cells to apoptosis.

Although the precise role for the tuberous sclerosis complex-2 tumor suppressor gene (Tsc2) in tumor suppression is not clear, many studies have implicated Tsc2 in the regulation of cell differentiation, cell cycle control, GTPase activity, transcription, polycystin-1 localization, and translation initiation. We propose that Tsc2 also increases susceptibility to apoptosis, and that this functional role may contribute to the tumor suppressor activity of Tsc2. We previously characterized the apoptotic response of a Tsc2-null renal tumor cell line (ERC-18) to the tumor promoter okadaic acid (OKA).

Making mechanistic connections between cell signaling pathways and pathological endpoints.

Cell signaling is a term used to describe a complex interactive system of signals that act to regulate or mediate a cellular response. Therapies that target cell signaling pathways have the potential to effectively reverse molecular deregulation underlying disease. The inherent complexity of cell signaling presents a major challenge to designing such therapies however, because perturbation of pathways has the potential to produce dramatic adverse effects.

The tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) provokes a prolonged morphologic response and ERK activation in Tsc2-null renal tumor cells.

Loss of tumor suppressor function dramatically alters the cellular response to chemicals. The phorbol ester tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA), stimulates cell proliferation through rapid activation of protein kinase C (PKC), followed by gradual degradation of the kinase. TPA also activates the GTPase Rap1 in some cell types.

Angiogenic inhibition mediated by a DNAzyme that targets vascular endothelial growth factor receptor 2.

The vascular endothelial growth factor receptor (VEGFR) is an important angiogenic target for cancer gene therapy. In this study, we designed an mRNA-cleaving oligodeoxynucleotide that targets the VEGF receptor 2 (VEGFR2) transcript (VEGFR2 DNAzyme). This DNAzyme was found to digest efficiently mRNA substrates of VEGFR2 in a concentration- and time-dependent manner.

Biochemical and morphological events during okadaic acid-induced apoptosis of Tsc2-null ERC-18 cell line.

Several tumor suppressor genes have been shown to regulate cellular susceptibility to proliferation or apoptotic cell death. An essential first step in studies with the long-range goal of determining the effect of a tumor suppressor gene on cellular susceptibility to apoptosis is careful characterization of the cell's response to an apoptotic stimulus. The goals of this study were to characterize the apoptotic response of a tuberous sclerosis complex-2 (Tsc2) tumor suppressor gene-null cell line, to establish valid biochemical events that can be used as apoptosis markers, and to determine how these events correlate with apoptosis-specific morphologic changes.