Prediction of clinically relevant safety signals of nephrotoxicity through plasma metabolite profiling.

Addressing safety concerns such as drug-induced kidney injury (DIKI) early in the drug pharmaceutical development process ensures both patient safety and efficient clinical development. We describe a unique adjunct to standard safety assessment wherein the metabolite profile of treated animals is compared with the MetaMap Tox metabolomics database in order to predict the potential for a wide variety of adverse events, including DIKI. To examine this approach, a study of five compounds (phenytoin, cyclosporin A, doxorubicin, captopril, and lisinopril) was initiated by the Technology Evaluation Consortium under the auspices of the Drug Safety Executive Council (DSEC). The metabolite profiles for rats treated with these compounds matched established reference patterns in the MetaMap Tox metabolomics database indicative of each compound's well-described clinical toxicities. For example, the DIKI associated with cyclosporine A and doxorubicin was correctly predicted by metabolite profiling, while no evidence for DIKI was found for phenytoin, consistent with its clinical picture. In some cases the clinical toxicity (hepatotoxicity), not generally seen in animal studies, was detected with MetaMap Tox. Thus metabolite profiling coupled with the MetaMap Tox metabolomics database offers a unique and powerful approach for augmenting safety assessment and avoiding clinical adverse events such as DIKI.

PhRMA survey of pharmacogenomic and pharmacodynamic evaluations: what next?

Interindividual variation in pharmacodynamic (PD) response to drugs is an ongoing area of research for drugs in clinical development, pre- and postapproval. To characterize how pharmacogenomic (PG ) variations can serves a predictor of differences in PD outcomes, the pharmaceutical industry has incorporated PG /PD analysis into clinical drug development. The Pharmaceutical Research and Manufacturers of America (PhRMA ) and the Industry Pharmacogenomics Working Group (I-PWG) conducted a survey of 16 pharmaceutical companies to ascertain to what extent PG/PD research is being incorporated into drug development. The survey results showed that, while the industry has made some attempt to incorporate PG/PD studies into drug development, application has been inconsistent. Nevertheless, several valid PG/PD markers have since emerged in drug labels. The I-PWG considers PG/PD research an important approach to improving success rates in drug development. This article reports the results of the survey and proposes steps toward increasing the use of PG/PD research by the industry.

Reverse transcriptase-polymerase chain reaction for prostate-specific antigen may be a prognostic indicator in breast cancer.

Among women with node-negative breast cancer and small tumours, it is important to identify those with tumours that will recur, so that they may receive adjuvant therapy, while sparing those with tumours that will not recur the hazards of adjuvant treatment. A reverse transcriptase-polymerase chain reaction (RT-PCR) for prostate-specific antigen (PSA) may be used to identify circulating metastatic cells in patients with prostate cancer. Approximately 30% of breast cancer cells also produce PSA. Therefore, we tested the PSA RT-PCR assay on blood specimens from women with breast cancer. We evaluated 78 women at Mount Sinai Medical Center with histologically confirmed breast cancer. Venous blood (5 cm3) from the women was collected in ethylene diaminetetraacetic acid (EDTA)-treated collection tubes and approximately 400 ng of RNA from each sample was subjected to an RT-PCR. We were able to detect the amplified PSA fragment in 18 of 78 women with breast cancer; 7 of the 18 women with the PSA fragment had localised, small, node-negative tumours, both oestrogen receptor (ER) positive and ER negative. We could not detect the amplified PSA fragment in 20 normal women and 22 normal men. We conclude that PSA RT-PCR may be a useful method for determining the presence of circulating metastatic cells in some women with node-negative breast cancer, and therefore the potential for these women to develop recurrent disease and thus benefit from adjuvant therapy.

Mouse and rat B-myc share amino acid sequence homology with the c-myc transcriptional activator domain and contain a B-myc specific carboxy terminal region.

B-myc is a member of the myc gene family. Previous studies indicate that the rat B-myc gene contains a single exon which shows 77% nucleotide homology to the second exon of the rat c-myc gene. Its open reading frame (ORF) encodes a polypeptide with a predicted molecular weight of 20 kD. We have isolated a new, larger rat B-myc genomic clone. Sequence analysis of this clone confirmed the presence of one single coding exon. Furthermore, a genomic mouse B-myc clone was identified and compared to the rat homolog. Nucleotide analysis of B-myc coding and non-coding sequences suggests that it may be a functional gene evolved by selective duplication of part of the second c-myc exon. Analysis of the rodent B-myc open reading frames revealed two in-frame amino acid duplications in mouse B-myc and a 96% conservation at the amino acid level. Both rat and mouse B-myc proteins contain an identical and unique stretch of 14 carboxy terminal amino acid residues not found in other myc proteins. In vitro translation of rat and mouse B-myc ORF's yielded proteins that migrated as 26 kD bands in SDS-PAGE and could be immunoprecipitated by a polyclonal panmyc antiserum. Immunostaining of human lymphoma cells transiently transfected with a B-myc expression vector showed that the protein was mainly localized to the nucleus.

Differential induction of stromelysin mRNA by bovine articular chondrocytes treated with interferon-gamma and interleukin-1 alpha.

Articular chondrocytes from rheumatoid joints have been shown to express class II major histocompatibility (MHC) antigens that were correlated with the presence of interferon-gamma (IFN-gamma) in the inflamed joint. Chondrocytes expressing MHC antigens function as antigen presenting cells and thus stimulate lymphocyte proliferation. These responses suggest a powerful role for the IFN-gamma stimulation of chondrocytes. The present studies were designed to examine the functional role of chondrocytes exposed to IFN-gamma during cartilage degradation that occurs in synovial disease. Destruction of cartilage in arthritis is partially attributable to metalloproteinases released by the chondrocytes in response to interleukin-1 (IL-1). Bovine articular chondrocytes treated with interleukin-1 alpha (IL-1 alpha) produced enhanced levels of stromelysin mRNA, however, Northern blots could not determine the percentage of cells responding. Exposure of bovine articular chondrocytes to IFN-gamma induced the expression of bovine HLA-DR (boHLA-DR) antigen in 50% of the cells. Using a modified cell sorting technique, chondrocytes that expressed class II MHC antigens produced two fold greater stromelysin mRNA than chondrocytes that did not express this antigen. In contrast, collagen type II mRNA levels were similar in chondrocytes, regardless of the expression of class II MHC antigens. In situ hybridization studies showed that less than half of all cartilage chondrocytes were induced to synthesize stromelysin mRNA. These observations suggest that IFN-gamma stimulates specific subpopulations of chondrocytes to be functionally active in inflammation-induced metalloprotease secretion.

A conserved sequence at c-myc oncogene chromosomal translocation breakpoints in plasmacytomas.

Many recent studies have shown that chromosomal translocation breakpoints frequently occur near cellular proto-oncogenes (reviewed in ref. 1). In both mouse plasmacytomas and Burkitt lymphomas, the c-myc oncogene becomes joined to an immunoglobulin heavy-chain gene in a head-to-head configuration. Within c-myc, the breaks frequently occur near the first exon-intron boundary, while within the immunoglobulin gene the breaks usually involve sequences directing heavy-chain switching. It has been assumed that the translocations represent abortive immunoglobulin switching events which have activated the c-myc gene for a role in tumour formation. However, sequence analysis of the c-myc gene does not reveal any apparent similarity to the immunoglobulin switch signals. With these results in mind, we have determined the precise breakpoints within c-myc for two plasmacytoma lines in order to search for any common features that may shed some light on the mechanism of chromosomal translocation. We report here that the tetranucleotide sequence GAGG occurs close to the breakpoint in five out of six translocations, and so may be a sequence recognized by either the enzymes that catalyse immunoglobulin heavy-chain switching, or some other DNA-cleaving activity.

Novel myc oncogene RNA from abortive immunoglobulin-gene recombination in mouse plasmacytomas.

We have found that the myc oncogene has been modified by abortive recombination with the alpha heavy-chain immunoglobulin constant-region (C alpha) gene in five different mouse plasmacytoma lines. Recombination occurred approximately 0.8-2.0 kb to the 5' side of two distinct coding regions, defined by sequence homology between the chicken cellular and plasmacytoma myc genes. The myc and C alpha genes were always in opposite transcriptional orientation, with the recombination site within the C alpha switch region sequences. DNA recombination was found to correlate with the production of a novel 2.1 kb species of myc RNA that was 0.4 kb shorter than the normal cellular transcript. No elevated levels of myc RNA were evident, suggesting that DNA rearrangements have altered the myc oncogene product. This oncogene activation corresponds to the chromosomal translocations found in nearly all plasmacytomas.

Amino acid sequence of Escherichia coli alkaline phosphatase.

The complete amino acid sequence of the Escherichia coli alkaline phosphatase subunit [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1, isozyme 3] has been determined. The monomer contains 449 amino acid residues in a single unglycosylated polypeptide chain having a calculated Mr of 47,029. Isozyme 1 has an additional arginine residue at the NH2 terminus that presumably results from variability in processing of precursor molecules. Sequence data were obtained from both manual and automatic Edman degradation of the tryptic and cyanogen bromide peptides, as well as other peptides derived therefrom. The two disulfide bonds were determined from analyses of the appropriate peptic peptides. This structure confirms earlier reports of the sequence surrounding the active-site serine and both the NH2- and COOH-terminal cyanogen bromide fragments. A secondary structure prediction places nearly half the residues in alpha-helical segments that have 13% and 16%, respectively, in beta-strand and beta-turn orientations.