RESUMEN
ERCC1 is an essential gene within the nucleotide excision repair process. We studied two human ovarian carcinoma cell lines for cisplatin resistance, which differed with respect to ERCC1. The A2780/CP70 cell line has been extensively studied previously, and has the wild-type ERCC1 sequence. The MCAS cell line has a recently described ERCC1 polymorphism at codon 118, which is associated with an approximate 50% reduction in codon usage. These cells did not differ with respect to p53 sequence nor p53 mRNA induction following cisplatin exposure. The induction of ERCC1 mRNA was markedly reduced in MCAS cells as compared to A2780/CP70 cells. At the IC50 cisplatin dose for each cell line, MCAS cells were less proficient at cisplatin-DNA adduct repair than A2780/CP70 cells. In absolute terms, A2780/CP70 cells repaired 3-fold as much adduct (2.7 pg/microgram DNA over 6 h vs 0.86 pg/microgram DNA); and when expressed in terms of the maximal DNA adduct load, A2780/CP70 cells repaired 50% more adduct than MCAS cells. MCAS cells had increased cytosolic inactivation of drug at the IC50 dose level, which has been previously suggested to be a compensatory cellular response for reduced DNA repair capacity. These data suggest the possibility that this specific ERCC1 polymorphism, may be associated with reduced DNA repair capacity in human ovarian cancer cells. This association may be effected through a reduction in peak production of ERCC1 mRNA, and a consequent reduction in the translation of ERCC1 mRNA into protein.
Asunto(s)
Antineoplásicos/farmacología , Cisplatino/farmacología , Codón , Proteínas de Unión al ADN , Endonucleasas , Neoplasias Ováricas/genética , Proteínas/genética , Cisplatino/metabolismo , Aductos de ADN/análisis , Reparación del ADN , Resistencia a Antineoplásicos , Femenino , Humanos , Neoplasias Ováricas/tratamiento farmacológico , Neoplasias Ováricas/patología , ARN Mensajero/análisis , Células Tumorales CultivadasRESUMEN
Cadmium (Cd), a toxic heavy metal and probable carcinogen in humans, appears to have potential anti-cancer activity in pre-clinical systems. This observation led us to develop a method for measuring cellular Cd and DNA-bound Cd following micromolar exposures to cadmium dichloride. Cultured human ovarian cancer cell lines were used. Following low level exposures to cadmium dichloride (CdCl2), atomic absorption spectrometry with Zeeman background correction was used to measure total cell associated Cd in wet-ashed cells, and the lower limits of detection was at 100 pg of Cd per 106 cells. In cellular DNA isolated by cesium chloride density gradient centrifugation, levels of 1.5 Cd lesions (Cd molecules) per 106 nucleotides were reproducibly detected. Standard curves with samples yielded 76.4 6.7% recovery when using picogram quantities of Cd. Manipulation of the total amount of biological material used, can further improve detection limits. Thus, this method is suitable for the detection of Cd in biological matrixes after low levels of Cd exposure, and shows good performance in terms of the level of sensitivity and reproducibility.
Asunto(s)
Cadmio/análisis , Espectrofotometría Atómica/métodos , Cloruro de Cadmio/farmacología , Calibración , ADN de Neoplasias/química , Femenino , Humanos , Neoplasias Ováricas/química , Manejo de Especímenes , Espectrofotometría Atómica/instrumentación , Células Tumorales Cultivadas/químicaRESUMEN
A survey of 381 special and regular educators assessed perceptions and opinions surrounding the regular education initiative. Confirmatory factor analysis supported an a priori hypothesized structure of teachers' responses. Items factored into 14 categories. These factors describe issues related to preferred placement of students with mild disabilities, teachers' responsibility and ownership, teacher preparedness for meeting the needs of these students, achievement outcomes for all children, and the changes that would result from adopting the proposed consultant model rather than a pullout program. Results favored current special education practices (pullout programs) in elementary schools.