Background: Clonal competition in cancer describes the process in which the progeny of a cell clone supersedes or succumbs to other competing clones due to differences in their functional characteristics, mostly based on subsequently acquired mutations. Even though the patterns of those mutations are well explored in many tumors, the dynamical process of clonal selection is underexposed. Methods: We studied the dynamics of clonal competition in a BcrAbl-induced leukemia using a γ-retroviral vector library encoding the oncogene in conjunction with genetic barcodes. To this end, we studied the growth dynamics of transduced cells on the clonal level both in vitro and in vivo in transplanted mice. Results: While we detected moderate changes in clonal abundancies in vitro, we observed monoclonal leukemias in 6/30 mice after transplantation, which intriguingly were caused by only two different BcrAbl clones. To analyze the success of these clones, we applied a mathematical model of hematopoietic tissue maintenance, which indicated that a differential engraftment capacity of these two dominant clones provides a possible explanation of our observations. These findings were further supported by additional transplantation experiments and increased BcrAbl transcript levels in both clones. Conclusion: Our findings show that clonal competition is not an absolute process based on mutations, but highly dependent on selection mechanisms in a given environmental context.

Background: Clonal competition in cancer describes the process in which the progeny of a cell clone supersedes or succumbs to other competing clones due to differences in their functional characteristics, mostly based on subsequently acquired mutations. Even though the patterns of those mutations are well explored in many tumors, the dynamical process of clonal selection is underexposed. Methods: We studied the dynamics of clonal competition in a BcrAbl-induced leukemia using a γ-retroviral vector library encoding the oncogene in conjunction with genetic barcodes. To this end, we studied the growth dynamics of transduced cells on the clonal level both in vitro and in vivo in transplanted mice. Results: While we detected moderate changes in clonal abundancies in vitro, we observed monoclonal leukemias in 6/30 mice after transplantation, which intriguingly were caused by only two different BcrAbl clones. To analyze the success of these clones, we applied a mathematical model of hematopoietic tissue maintenance, which indicated that a differential engraftment capacity of these two dominant clones provides a possible explanation of our observations. These findings were further supported by additional transplantation experiments and increased BcrAbl transcript levels in both clones. Conclusion: Our findings show that clonal competition is not an absolute process based on mutations, but highly dependent on selection mechanisms in a given environmental context.

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No. of bitstreams: 2 Tese - Adriana do Prado Barbosa - 2015.pdf: 900945 bytes, checksum: c7a5ed7dcaeb54e2967829169a9de269 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-04-10 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The treatment of chronic myeloid leukemia (CML) has changed dramatically with the advent of imatinib mesylate (IM). Besides the convenience of oral use, other benefits were achieved with the new drug, with faster therapeutic responses and increased survival, giving the CML similar characteristics as chronic diseases. In this scenario, there was another challenge, drug compliance, since a significant proportion of patients fail to ingest all the prescribed doses of imatinib. The concern was to optimize the adherence of CML patients, the hematology ambulatory at the Clinical Hospital of the Federal University of Goias (HC-UFG), led the authoress to create a film cartoon, as a pro-adhesion educational intervention model. To investigate the effectiveness of this new educational material, we used in 65 patients three adherence measures, two indirect (Morisky Test and Molecular Response [MR]) and direct (plasma dosage of IM), before and after the screening of film. In univariate analysis, from the Morisky Test, the film was striking, with increased adherent patients, which increased from 15 (23.1%) to 43 (66.1%). The results of MR showed an improvement trend after the movie, because the positive molecular response (major MR or complete MR) increased from 81.5% to 86.1%. Regarding the serum levels of IM, with daily doses of 400-800 mg IM, the premovie samples showed higher average than the post-movie (2473.16 ± 1049.55 ng/ml versus 1414.72 ± 715 73 ng/ml), with a variation coefficients interpatients of 43.4% and 50.6%, respectively. This high dispersion index found has been reported by other authors. By multivariate analysis, patients were divided into three groups. The first brought together compliant patients before and after the film with a good therapeutic response (major MR) after the intervention. It was: patients over 53 years old, females, with associated diseases before and after the treatment of CML that use more than two drugs in addition to imatinib. The second group was marked by the change of not adherence pre to adherence post-film. Its features were younger than or equal to 53, the absence of other disease before the CML, the use of less than two drugs and complete molecular response after the film. In the third group, we observed patients without molecular response before and after the educational intervention and no medication adherence after the film. They had in common their age (less than or equal to 53 years), and drug discontinuation due to adverse reactions. The last represents the set of patients resistant to the educational film, drawing attention to the fact that only one pro-adhesion method may be insufficient for all individuals. It is concluded that medication adherence was higher among patients older than 53 years, the educational film is an effective proadhesion assistance and continuing education, if combined with another method, it could help maintain or enhance the benefits achieved in this work. / O tratamento da leucemia mielóide crônica (LMC) mudou radicalmente com o advento do mesilato de imatinibe (MI). Além da comodidade do uso oral, outros benefícios foram alcançados com o novo fármaco, como respostas terapêuticas mais rápidas e aumento da sobrevida, dando `a LMC características semelhantes `as de doenças crônicas. Neste cenário, surgiu outro desafio, a adesão medicamentosa, pois uma proporção significativa de pacientes deixa de ingerir a dose prescrita de imatinibe. A preocupação em otimizar a adesão dos pacientes com LMC, do Ambulatório de Hematologia do Hospital das Clínicas da Universidade Federal de Goiás (HC-UFG), motivou a autora a criar um filme em desenho animado, como modelo de intervenção educativa pró-adesão. Para investigar a eficácia deste novo material educativo, empregou-se, em 65 pacientes, três medidas de adesão, duas indiretas (Teste de Morisky e Resposta Molecular [RM]) e uma direta (dosagem plasmática do MI), antes e depois da exibição do filme. Em análise univariada, pelo teste de Morisky, o filme foi impactante, com aumento dos pacientes aderentes, que passaram de 15 (23,1%) para 43 (66,1%). Os resultados da RM indicaram uma tendência de melhora após o filme, pois a resposta molecular positiva (RM maior ou RM completa) passou de 81,5% para 86,1%. Em relação `a dosagem sérica do MI, com doses diárias entre 400-800 mg de MI, as amostras pré-filme apresentaram média superior `as do pósfilme (2.473,16 ± 1.049,55 ng/ml versus 1.414,72 ± 715,73 ng/ml), com coeficientes de variação interpaciente de 43,4% e 50,6%, respectivamente. Este elevado índice de dispersão encontrado tem sido relatado por outros autores. Pela análise multivariada, os pacientes foram separados em três grupos. O primeiro, reuniu os pacientes aderentes antes e após o filme e com boa resposta terapêutica (RM maior) após a intervenção. Foram eles: os doentes com mais de 53 anos, do gênero feminino, com doenças associadas antes e após o tratamento da LMC e que usam mais de dois medicamentos além do imatinibe. O segundo grupo foi marcado pela mudança de não adesão pré para adesão pós-filme. Suas características foram idade menor ou igual a 53, ausência de outra doença antes da LMC, uso de menos de dois medicamentos e resposta molecular completa pós-filme. No terceiro grupo, observou-se pacientes sem resposta molecular antes e depois da intervenção educativa, bem como não adesão medicamentosa após o filme. Eles tinham em comum a idade, menor ou igual a 53 anos, e suspensão do medicamento por reação adversa. Estes últimos representam o conjunto de pacientes resistentes ao filme educacional, chamando atenção para o fato de que somente um método pró-adesão pode ser insuficiente para todos os indivíduos. Conclui-se que a adesão medicamentosa foi maior entre os pacientes maiores de 53 anos, que o filme educativo é uma intervenção pró-adesão eficaz e que a educação continuada, aliada a outro método, poderia ajudar a manter ou ampliar os benefícios conquistados neste trabalho.