Polyamines are excellent stabilizers of triplex DNA. Recent studies in our laboratory revealed a remarkable structural specificity of polyamines in the induction and stabilization of triplex DNA. 1,3-Diaminopropane (DAP) showed optimum efficacy amongst a series of synthetic diamines in stabilizing triplex DNA. To utilize the potential of this finding in developing an anti-gene strategy for breast cancer, we treated MCF-7 cells with a 37mer oligonucleotide to form triplex DNA in the up-stream regulatory region of the c-myc oncogene in the presence of DAP. As individual agents, the oligonucleotide and DAP did not downregulate c-myc mRNA in the presence of estradiol. Complexation of the oligonucleotide with 2 mM DAP reduced c-myc mRNA signal by 65% at 10 microM oligonucleotide concentration. In contrast, a control oligonucleotide had no significant effect on c-myc mRNA. The expression of c-fos oncogene was not significantly altered by the triplex forming oligonucleotide (TFO). DAP was internalized within 1 h of treatment; however, it had no significant effect on the level of natural polyamines. These data indicate that selective utilization of synthetic polyamines and TFOs might be an important strategy to develop anti-gene-based therapeutic modalities for breast cancer.

Estrogens stimulate the growth of a majority of estrogen receptor (ER)-positive breast cancer cells. In contrast, estradiol exerted a 75% inhibition of DNA synthesis in the MCF-10AE(wt5) cell line, obtained by the transfection of the ER gene into a normal breast epithelial cell line, MCF-10A. The estradiol-mediated growth inhibitory effect was reversed by ICI 164384, a pure anti-estrogen. Analysis of cell cycle by flow cytometry showed a significant increase of G1 cells by estradiol treatment compared to controls. To understand the mechanism of action of estradiol on MCF-10AE(wt5) cells, we examined the level of a cyclin dependent kinase inhibitor (CKI), p21, by Western blot analysis. Our results showed a 5- to 10-fold increase in the level of p21 in estradiol-treated MCF-10AE(wt5) cells compared to controls. ICI 164384 reversed estradiol-mediated induction of p21. Northern blot analysis of p21 mRNA indicated that estradiol stimulated its message in MCF-10AE(wt5) cells. Analysis of a panel of 6 breast cancer cell lines showed the absence of p21 protein, whereas it was present at a very low level in MCF-10A cells. Comparison of p21 in MCF-10A and MCF-10AE(wt5) cells showed an abundance of p21 in the ER-transfected cells. However, this p21 appears to be inactive in the absence of estradiol. These results suggest a p21-mediated pathway as a possible mechanism for the growth inhibitory effects of estradiol on at least a subset of ER-transfected cell lines.

Linear polyamines are excellent promoters of triplex DNA formation. The effects of structural rigidization of polyamines on triplex DNA stability are not known at present. We wished to develop a series of polyamine analogs as secondary ligands for triplex DNA stabilization for antigene applications. To accomplish this goal, we synthesized cyclopolyamines by interconnecting the two amino or imino groups of linear polyamines with a --(CH2)n-bridge (n=3,4,5). Melting temperature (Tm) data showed that [4,3]-spermine and [4,4]-spermine stabilized poly(dA) x 2poly(dT) triplex at >25 microM concentrations (Tm = 71 degrees C at 100 microM). The dTm/dlog [polyamine] values for these compounds were 26 and 40, respectively. [4,3]-Spermine and [4,4]-spermine also stabilized triplex DNA formed by a purine-motif triplex-forming oligonucleotide, TG3TG4TG4TG3T with its target duplex, as determined by Tm, circular dichroism (CD) spectroscopy, and electrophoretic mobility shift assay (EMSA). In contrast, [4,4]-putrescine and [4,5]-putrescine as well as [4,5]-spermine had no triplex DNA stabilizing effect. CD spectra also showed triplex DNA aggregation and psi-DNA formation at >100 microM [4,3]-spermine. These data demonstrate that structural rigidization of linear polyamines has a profound effect on their ability to stabilize triplex DNA and provoke conformational transitions.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions tor reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports. 1215 Jefferson Davis Highway, Suite 1204, Arlington. VA 22202-4302, and AUTHOR(S)Srivani Balabhadrapathruni T. Thomas During the 3 years of my pre-doctoral research supported by the U.S. Army's Breast Cancer Research Program, I studied estrogen receptor (ER)-dependent and -independent effects of five structurally related phytoestrogens on breast cancer cell growth and apoptosis. Our studies showed that genistein binds to the ER with lower affinity compared to estradiol. However, genistein-bound ER is a 4S monomeric protein, while estradiol-bound ER is multimeric in our sucrose density gradient experiments. We also showed that genistein-ERß complex bound to the consensus estrogen responsive element (ERE) with high affinity. In contrast, genistein bound to ERoc did not significantly bind to the ERE. These results suggest that genistein and estradiol exert different effects on ER-mediated functions. FUNDING NUMBERS DAMD17-97-1-7035 PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)UniversityIn ER-negative cells, genistein and quercetin inhibited cell growth and induced apoptosis in a dosedependent manner. Daidzein, kaempferol and biochanin A were less effective. The mechanism of growth inhibition in ER-positive and ER-negative breast cancer cells by genistein and quercetin included G2/M cell cycle arrest and alterations in cyclin Bl protein. Our results suggest that genistein and quercetin may be developed as chemotherapeutic agents against treatment of ER-negative tumors. 4>h Where copyrighted material is quoted, permission has been obtained to use such material. SUBJECT TERMS Breast Cancer NUMBER OF PAGES 62 PRICE CODEM?j> where material from documents designated for limited distribution is quoted, permission has been obtained to use the material.rMfr Citations of commercial organizations and trade names in this report do not constitute an official Department of Army endorsement or approval of the products or services of these organizations.N/A In conducting research using animals, the investigator(s) adhered to the "Guide for the Care and Use of Laboratory Animals," prepared by the Committee on Care and use of Laboratory Animals of the Institute of Laboratory Resources, national Research Council (NIH Publication No. 86-23, Revised 1985).iK For the protection of human subjects, the investigator(s) adhered to policies of applicable Federal Law 45 CFR 46.N/A In conducting research utilizing recombinant DNA technology, the investigator(s) adhered to current guidelines promulgated by the National Inst...