Biomedical subjects

L A Rosario

Publications and source records attributed to L A Rosario.

3 recordsLinked to original sources

PubMed2001

Pharmacologic or genetic manipulation of glutathione S-transferase P1-1 (GSTpi) influences cell proliferation pathways.

Glutathione S-transferase P1-1 (GSTpi) is an abundant and ubiquitously expressed protein in normal and malignant mammalian tissues and possesses catalytic and ligand binding properties. Our present data suggest that the protein contributes to the regulation of cell proliferation. Mouse embryo fibroblasts (MEFs) isolated from mice with a GSTP1-1 [glutathione S-transferase P1-1 (isozyme in nonhepatic tissue)] null genotype (GSTpi(-/-)) doubled their population in 26.2 h versus 33.6 h for the wild type (GSTpi(+/+)). Retroviral transfection of GSTP1-1 into GSTpi(-/-) MEF cells slowed the doubling time to 30.4 h. Both early passage and immortalized MEF cells from GSTpi(-/-) animals expressed significantly elevated activity of extracellular signal-regulated kinases ERK1/ERK2, kinases linked to cell proliferation pathways. In vivo, GSTpi(-/-) mice had higher basal levels of circulating white blood cells compared with GSTpi(+/+). Administration of a peptidomimetic inhibitor of GSTP1-1, TLK199, (gamma-glutamyl-S-(benzyl)cysteinyl-R-phenyl glycine diethyl ester), stimulated both lymphocyte production and bone marrow progenitor (colony-forming unit-granulocyte macrophage) proliferation, but only in GSTpi(+/+) and not in GSTpi(-/-) animals. Selection of a resistant clone of an HL60 tumor cell line through chronic exposure to TLK199 resulted in cells with elevated activities of c-Jun NH2 terminal kinase (JNK1) and ERK1/ERK2, and allowed the cells to proliferate under stress conditions that induced high levels of apoptosis in the wild type cells. The in vitro and in vivo data are consistent with the principle that GSTP1-1 influences cell proliferation.

Animals↗

PubMed2000

Cellular response to a glutathione S-transferase P1-1 activated prodrug.

TER286 [gamma-glutamyl-alpha-amino-beta(2-ethyl-N,N,N', N'-tetrakis(2-chloroethyl)phosphorodiamidate)-sulfonyl-propionyl-( R)- (-) phenylglycine] is a novel nitrogen mustard prodrug that is preferentially activated by glutathione S-transferase P1-1 (GSTP1-1). A human promyelocytic leukemia /TER286-resistant cell line was selected by chronic, long-term exposure to the prodrug. Although resistance was not readily achieved, eventually a 5-fold resistant clone was isolated. Cross-resistance to melphalan occurred, but not to doxorubicin (Adriamycin), taxol, and gamma-glutamyl-S-(benzyl)cysteinyl-R(-)-phenyl glycine diethyl ester, a GSTP1-1 inhibitor. The protein and transcript levels and enzymatic activity of GSTP1-1 were reduced significantly in the selected resistant line. GSTalpha levels were unchanged, and GSTmu was undetectable. Although glutathione levels were elevated in human promyelocytic leukemia/TER286 cells, no changes in the expression of thiol-related genes including gamma-glutamylcysteine synthetase, gamma-glutamyl transpeptidase, or multidrug resistance protein were found. A 7-fold increase in catalase expression in the resistant cell line indicated an adaptive response to oxidative and electrophilic stress, and this was also reflected in the lower prevalence of drug-induced DNA single-strand breaks in the resistant cells. Mouse embryo fibroblast GSTP1-1(-/-) cells exhibited 2-fold resistance to TER286 compared with GSTP1-1(+/+) cells. NIH3T3 cells transfected with combinations of gamma-GCS and multidrug resistance protein exhibited enhanced resistance to TER286, although the degree of resistance was impaired by cotransfection of GSTP1-1. These results are consistent with responses in the TER286-resistant cells indicative of GSTP1-1-mediated mechanism of activation. In consequence, these data support the rationale that tumors expressing high levels of GSTP1-1 will be more sensitive to the cytotoxic effects of the drug.

3T3 Cells↗

PubMed1999

Individual differences in behavioral reactivity: correlation with stress-induced norepinephrine efflux in the hippocampus of Sprague-Dawley rats.

The present studies investigate the hypothesis that the locus coeruleus-norepinephrine (LC-NE) system plays a role in the neural substrates underlying individual differences in behavioral reactivity to stress. Individuals were selected from a random sample of Sprague-Dawley rats and categorized as a high responder (HR), middle responder (MR), or low responder (LR) based on the initial locomotor response to a novel open field. Rats with behavioral scores at least 1 SD away from the mean for the subject sample were categorized as HR or LR rats. Middle responder rats exhibited locomotor scores representative of the mean locomotor activity of the population sample. Locomotor activity scores measured 6 days after the initial determination were similar to scores obtained in the original screening, suggesting that the locomotor response to novelty is a stable individual trait. Additionally, locomotor activity during the dark phase of the diurnal cycle was not different among the groups, suggesting that differences in locomotor activity in response to a novel open field are an index of behavioral reactivity to the stressful situation rather than an indicator of global differences in motoric activity. In vivo microdialysis was used to measure extracellular levels of hippocampal NE in the hippocampus. During baseline conditions, the efflux of hippocampal NE was similar among HR, MR, and LR rats. In response to tail-pinch stress, hippocampal NE release was elevated in all groups. This response was significantly greater in HR compared to LR rats. Across all groups, locomotor response in the novel open field was significantly correlated with the magnitude of NE release in response to subsequent application of tail-pinch stress. In contrast, administration of 1.5 mg/kg, i.p., amphetamine resulted in a similar elevation of extracellular NE level among HR, LR, and MR rats. These data suggest that activation of the LC-NE system may be involved in determining the behavioral response of individuals to environmental stress.

Amphetamine↗