Accession Number : ADA300112

Title :   A Novel Model System to Examine Agents Used in Breast Cancer Therapy.

Descriptive Note : Annual rept. 1 Jul 94-30 Jun 95,

Corporate Author : MARYLAND UNIV BALTIMORE SCHOOL OF MEDICINE

Personal Author(s) : Coll, Jennifer ; Malkas, Linda H.

PDF Url : ADA300112

Report Date : JUL 1995

Pagination or Media Count : 35

Abstract : We have recently characterized a multiprotein DNA replication complex (MRC) that was purified from NODA NIB 468 human breast cancer cells by a series of differential centrifugations polyethylene glycol precipitation and anion-exchange column chromatography (Coll et al., in preparation). The breast cell MRC exhibits a sedimentation coefficient of 185 in a continuous sucrose gradient. In the presence of viral large T-antigen and simian virus 40 (SV4O) origin sequences, the MRC executes all of the steps required for the in vitro, bidirectional replication of the SV4O genome. Several of the DNA replication enzymes comprising the NIRC have been identified by Western blot analyses and enzyme assays: DNA polymerase a-primase, DNA polymerase sigma, proliferating cell nuclear antigen (PCNA), RE-C RP-A and DNA topoisomerase I. Based upon its requirements for DNA replication activity and its ability to synthesize intermediate and full-length daughter DNA molecules, the MRC accurately depicts the DNA synthetic process as it occurs in vitro. Therefore, the MRC may serve as a novel model system to investigate the mechanisms of action of anticancer agents that directly target cellular DNA synthesis. Our initial studies on the interaction of camptothecin, a topoisomerase I inhibitor, with the MRC support its use as a model system (Coll et al., in press). Further studies may contribute important information about the cytotoxic effects of camptothecin, particularly the cellular consequences of camptothecin-DNA-topoisomerase-t cleavable complex formation.

Descriptors :   *DEOXYRIBONUCLEIC ACIDS, *MEDICAL EXAMINATION, *CANCER, *MAMMARY GLANDS, INTERACTIONS, SYNTHESIS, MOLECULES, CELLS, ENZYMES, POLYMERIZATION, PRECIPITATION, THERAPY, CYTOTOXINS, INHIBITORS, ASSAYING, GRADIENTS, POLYETHYLENE, GLYCOLS, SUCROSE.

Subject Categories : Medicine and Medical Research
      Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE