Ethonafide is an anthracene-containing derivative of amonafide that belongs to the azonafide series of anticancer agents. The lack of cross-resistance in MDR-expressing cancer cell lines and the absence of a quinone and hydroquinone moiety make ethonafide a possible less-cardiotoxic replacement for existing anthracene-containing anticancer agents, such as mitoxantrone and doxorubicin. For this study, we investigated the anticancer activity and mechanism of action of ethonafide in human prostate cancer cell lines. Ethonafide was cytotoxic against three human prostate cancer cell lines at nanomolar concentrations. Ethonafide was also found to be better tolerated and more effective at inhibiting tumor growth compared to mitoxantrone in DU 145 prostate cancer-bearing mice. Mechanistically, we found that ethonafide inhibits topoisomerase II activity in human prostate cancer cell lines and equally inhibits purified topoisomerase IIα and recombinant topoisomerase IIβ. The inhibition of topoisomerase II activity was due to stabilization of the cleavable complex, involving both topoisomerase IIα and β. By creating stable DU 145 cell lines with decreased expression of either topoisomerase IIα or β, we found that topoisomerase IIα is necessary for ethonafide-induced cytotoxicity. The decrease in sensitivity to ethonafide was due to a decrease in DNA damage and an increase in DNA repair as measured by the neutral comet assay. Additionally, ethonafide induces potent G₂ cell cycle arrest in the DU 145 human prostate cancer cell line. Ethonafide also induces apoptosis as measured by procaspase and PARP cleavage. In conclusion, we have identified ethonafide as a topoisomerase II poison and determined that it is topoisomerase IIα-specific in the DU 145 human prostate cancer cell line. Due to ethonafide’s activity in vitro and in vivo, decreased toxicity in mice compared to mitoxantrone, and its activity in multi-drug resistant cancer cell lines, ethonafide may be a suitable replacement to mitoxantrone for the treatment of hormone-refractory prostate cancer.

Thesis (Ph. D. in Biochemistry)--Vanderbilt University, Dec. 2005. / Title from title screen. Includes bibliographical references.

Exposure to benzene, a ubiquitous environmental pollutant, has been linked to leukemogenesis, although the mechanism of benzene initiated carcinogenesis remains unclear. It has been proposed that benzene can be bioactivated to toxic metabolites such as 1,4 benzoquinone (BQ), which can alter signalling pathways and affect chromosomal integrity. BQ has been shown to increase the activity of c-Myb, which is an important transcription factor involved in hematopoiesis, cell proliferation, and cell differentiation. The c-Myb protein also increases topoisomerase IIα (topo IIα) promoter activity specifically in cell lines with hematopoietic origin. Topo II is a critical nuclear enzyme that removes torsional strain by cleaving, untangling and religating double-stranded DNA. Since topo II mediates DNA strand breaks, aberrant topo II activity or increased protein levels may increase the formation of DNA strand breaks, leaving the cell susceptible to mutational events. I hypothesize that BQ increases c-Myb activity, which in turn increases topo IIα promoter activity resulting in increased DNA strand breaks. Using luciferase reporter assays in K-562 cells (human chronic myeloid leukemic cells) I confirmed that BQ exposure (25 and 37 µM) caused an increase in c-Myb activity after 24 hours. Contradictory to previous findings, overexpression of exogenous c-Myb or a polypeptide consisting of c-Myb’s DNA binding domain (DBD), which competitively inhibits the binding of endogenous c-Myb to DNA, did not affect topo IIα promoter activity. However, BQ exposure (37 µM for 24 hours) caused a significant increase in topo IIα promoter activity, which could be blocked by the overexpression of the DBD polypeptide. Western immunoblotting analysis did not show any significant increases in topo IIα protein levels in cells exposed to 37 µM BQ for 24 hours. Overall, this study suggests that BQ exposure increases topo IIα promoter activity through the c-Myb signalling pathway and furthers our understanding of BQ-mediated toxicity. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2008-01-02 14:09:00.011

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 213-221). Available also in a digital version from Dissertation Abstracts.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 103-116). Also available in electronic version.

Thesis (Ed. D.)--Illinois State University, 1990. / Title from title page screen, viewed November 28, 2005. Dissertation Committee: Herman E. Brockman (chair), Alan J. Katz, Lynne A. Lucher, Radheshyam K. Jayaswal, David F. Weber, Anthony E. Liberta. Includes bibliographical references (leaves 114-131) and abstract. Also available in print.

No description available.

Orientadores: Luiz Carlos Teixeira, Marcelo Alvarenga / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-09-11T21:07:48Z (GMT). No. of bitstreams: 1 Manna_ElizaDelFiol_M.pdf: 877307 bytes, checksum: 7ee78365634d93a3ce0c44565891f5ee (MD5) Previous issue date: 2005 / Resumo: Objetivo: O objetivo deste estudo foi avaliar a associação entre a expressão imunoistoquímica da topoisomerase IIa, HER2 e receptores hormonais e a resposta à quimioterapia primária baseada em antraciclina em carcinoma invasivo de mama. Materiais e Métodos: Analisamos 109 prontuários de pacientes tratadas com quimioterapia primária baseada em antraciclina no Centro Atenção Integral à Saúde da Mulher da Universidade Estadual de Campinas, no período de 1996 a 2004. As respostas clínica e patológica à quimioterapia primária foram associadas com a superexpressão da topoisomerase IIa e do HER2 e com a negatividade dos receptores hormonais. A análise estatística foi realizada através do teste qui-quadrado ou teste exato de Fisher. Resultados: A freqüência da superexpressão da topoisomerase IIa foi de 41%. Não houve associação estatística entre a resposta clínica e a superexpressão da topoisomerase IIa, do HER2 e negatividade dos receptores hormonais. Entretanto, houve associação entre a resposta completa patológica e a negatividade dos receptores hormonais (p=0,0289). Conclusões: O presente estudo sugere que esses marcadores não deveriam ser considerados fatores preditivos de resposta à quimioterapia primária com antraciclina, sendo necessários estudos prospectivos desenhados para esse propósito / Abstract: Background: The aim of this study was to evaluate the association between immunohistochemical expression of topoisomerase IIa, HER2 and hormonal receptors and response to primary anthracyclin-based chemotherapy in invasive breast carcinoma. Materials and Methods: We analyzed 109 medical charts of patients treated with primary anthracyclin-based chemotherapy in Women¿s Integral Health Care Center of State University of Campinas from 1996 to 2004. The clinical and pathological response to primary chemotherapy was associated with overexpression of topoisomerase IIa and HER2 and hormonal receptor negativity. Statistical analysis was performed using Chi-square or Fisher¿s Exact Test. Results: The frequency of topoisomerase IIa overexpression was 41%. No statistical association between clinical response and overexpression of topoisomerase IIa, HER2 and hormonal receptor negativity was found. However, there was an association between complete pathological response and hormonal receptor negativity (p=0.0289). Conclusions: The present study suggested that these markers should not be considered predictors of response to primary anthracyclin-based chemotherapy, and prospective studies must be designed for this purpose / Mestrado / Ciencias Biomedicas / Mestre em Tocoginecologia

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references (leaves 227-256). Issued in print and online. Available via ProQuest Digital Dissertations.

Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-29T19:15:47Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Reprodução Não Autorizada.pdf: 47716 bytes, checksum: 0353d988c60b584cfc9978721c498a11 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-29T19:16:10Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Reprodução Não Autorizada.pdf: 47716 bytes, checksum: 0353d988c60b584cfc9978721c498a11 (MD5) / Made available in DSpace on 2017-08-29T19:16:10Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Reprodução Não Autorizada.pdf: 47716 bytes, checksum: 0353d988c60b584cfc9978721c498a11 (MD5) Previous issue date: 2011-08-31 / Dermatophytes comprise a group of filamentous fungi of great interest on public health because of their ability to parasitize keratinized tissues, such as skin, hair and nails, and for their wide distribution in the world. As a consequence of this parasitism, an infectious process of dermatophytosis is established, from which a variety of clinical manifestations can occur, affecting people of both genders and all age groups. Laboratory methods for mycological diagnosis do not always allow a clear an especific definition of the agent. In this study, different strategies for extraction of DNA, and molecular typing by PCR-RFLP, of seven dermatophyte species were assessed. Two target regions: ITS/rDNA and the topoisomerase II gene were evaluated, by testing three PCR protocols and three restriction enzymes (DdeI, HinfI, HaeIII). For the DNA extraction, the glass bead shaking technique for cell lysis, followed by Gustincich (1991) based mehod for DNA separation, demonstrated more advantages. Our results has demonstrated that the topoisomerase II gene is a suitable target region for identification of the seven major pathogenic dermatophyte fungal species, reinforcing previous studies, and pointed to a new PCR-RFLP protocol, which is based on a PCR of this gene using dPsD2 primer, followed by digestion of PCR products with HaeIII restriction enzyme. / Os dermatófitos compreendem um grupo de fungos filamentosos de grande interesse na área da saúde, devido à sua capacidade de parasitar os tecidos queratinizados, como a pele, pêlos e unhas, e à sua ampla distribuição no mundo. Como conseqüência desse parasitismo instala-se um processo infeccioso de dermatofitose, a partir do qual pode ocorrer uma diversidade de manifestações clínicas, acometendo pessoas de ambos os gêneros e de todos os grupos etários. Os métodos laboratoriais para o diagnóstico micológico nem sempre permitem uma clara definição do agente em nível de espécie. No presente estudo foram analisadas diferentes estratégias para a extração de DNA e para a identificação molecular por PCR-RFLP das principais espécies de dermatófitos. Duas regiões alvo, a região ITS/DNAr e o gene da topoisomerase II foram analisadas, testando-se três protocolos de PCR e três enzimas de restrição (DdeI, HinfI, HaeIII). Na extração do DNA, o método de lise utilizando pérolas de vidro e a separação do DNA com base no método de Gustincich (1991) demonstrou importantes vantagens. Nossos resultados demonstraram que o gene da topoisomerase II é uma região alvo adequada para identificação das sete principais espécies de fungos dermatófitos patogênicos, reforçando estudos anteriores, e apontaram para um novo protocolo de RFLP-PCR, que se baseia em uma PCR desse gene utilizando o primer dPsD2, seguido da digestão dos produtos obtidos com a enzima de restrição HaeIII.