Comparative gene expression profiling in three primary human cell lines after treatment with a novel inhibitor of Rho kinase or atorvastatin.

Inhibitors of Rho kinase (ROCK) are a relatively new class of drugs with potential benefits in oncology, neurology, and fibrotic and cardiovascular diseases. ROCK inhibitors modulate many cellular functions, some of which are similar to the pleiotropic effects of statins, suggesting additive or synergistic properties. Studies to date have used compounds that inhibit both isoforms of ROCK, ROCK1 and ROCK2. This study was designed to compare gene expression profiles of atorvastatin with the newly developed ROCK2 inhibitor SLx-2119 in primary cultures of normal human endothelial cells, smooth muscle cells, and fibroblasts. Cells were treated with each compound for 24 h, after which total RNA was isolated and genome-wide gene-expression profiles were obtained with Illumina arrays. Because of the known effect of statins on the actin cytoskeleton and on connective tissue growth factor, a prominent growth factor involved in tissue fibrosis, the effects of SLx-2119 and atorvastatin on the actin cytoskeleton and connective tissue growth factor mRNA were also examined in cultures of smooth muscle cells with a fibrotic phenotype, isolated from biopsies of human intestine with radiation-induced fibrosis. Although SLx-2119 and atorvastatin affected expression of genes belonging to the same biological processes, individual genes were mostly different, consistent with synergistic or additive properties. Both SLx-2119 and atorvastatin reduced connective tissue growth factor mRNA and remodeled the actin cytoskeleton in fibrosis-derived smooth muscle cells, suggesting that both compounds have antifibrotic properties. These results form the basis for further studies to assess the possible therapeutic benefit of combined treatments.

Cytochrome P450 inhibition assays using traditional and fluorescent substrates.

A key liability in transitioning a new chemical entity (NCE) to a development candidate is NCE-related inhibition (or induction) of cytochrome P450 enzymes, a superfamily of heme-containing oxygenases that are the major route of first-pass metabolism for the majority of marketed drugs. The drawback of a drug/NCE that modulates CYP450 enzyme activity occurs when the compound is co-administered with another drug that relies on the same P450 enzyme for its metabolism. This could result in overdose of the second drug in the case of inhibition, or more rapid metabolism of one or both drugs accompanied by loss of efficacy in the case of enzyme induction. Screening for the inhibition of CYP450 enzymes is now routine in the early stages of evaluating NCEs. This unit describes two inhibition assays using traditional and fluorescent substrates.