El cáncer de mama es la neoplasia más frecuente en la población femenina mundial y una de las principales causas de muerte por cáncer. Algunos de los tratamientos convencionales para tratarlo (como la quimioterapia) generan efectos secundarios muy tóxicos, dado que suelen afectar a todas las células en división activa (sanas y tumorales). Por ello, son necesarios tratamientos específicos, con terapias dirigidas a las características moleculares del tumor y su microambiente. Una aproximación a ello podría ser la búsqueda de compuestos naturales con capacidad inmunopotenciadora y toxicidad selectiva sobre células tumorales. Recientemente, se han descubierto actividades inmunomoduladoras y antitumorales en diversos hongos. Entre ellos, los β-glucanos de Fracción D de Grifola frondosa (Maitake) son capaces de generar respuestas inmunes innatas y adaptativas, ejerciendo efectos antitumorales. Los beneficios terapéuticos reportados del tratamiento de la tumorigénesis mamaria con Fracción D de Maitake requieren profundizar aspectos farmacológicos y toxicológicos de sus moléculas bioactivas, para garantizar inocuidad y eficacia en la administración a un paciente. Por ello, los ensayos planteados en este trabajo tuvieron como finalidad elucidar aspectos toxicológicos, farmacodinámicos y farmacocinéticos de los ß-glucanos de Fracción D. De este modo, esperamos realizar un aporte significativo al conocimiento farmacológico de estos compuestos bioactivos promoviendo una estrategia inmunoterapéutica y antitumoral novedosa, destinada a la prevención de la carcinogénesis mamaria por medio de la administración de compuestos naturales. A través de nuestro trabajo aquí presentado, hemos demostrado en cultivos in vitro que Fracción D induce muerte apoptótica de células tumorales mamarias tanto murinas LM3 (hormono independientes) como humanas MCF-7 (hormono dependientes), mientras que no afecta la viabilidad de células mamarias normales MCF-10F. Hallamos que los ß-glucanos del extracto actúan a través de receptores Dectina-1 para inducir apoptosis tumoral, y además son capaces de modificar el perfil de expresión de una amplia variedad genes con diversidad de funciones, entre ellos genes específicos de apoptosis asociados a la supresión del fenotipo tumoral mamario, y genes asociados a procesos celulares cuya desregulación se vincula al desarrollo y progresión tumoral. Nuestros estudios farmacocinéticos in vivo de administración oral e intravenosa en modelos murinos demostraron que Fracción D presenta más de un pico de concentración plasmática máxima. Posee alto volumen de distribución, y es captado principalmente a nivel gastrointestinal. Pese a su estructura voluminosa y alto peso molecular, es capaza de llegar a cerebro. Demostramos que Fracción D previene el desarrollo de tumores mamarios en ratones hembra BALB/c, reduce la angiogénesis tumoral e incrementa la sobrevida total. Una dosis de 5 mg/kg/día administrada por 15 días es capaz de bloquear en más del 40% el proceso tumorigénico, mientras que, si el período de prevención se extiende a 50 días, la prevención tumoral ¡es del 100%! Su toxicidad aguda y subaguda es escasa, incluso a dosis 400 veces superior a la terapéutica, situándose la DL50 por encima de los 2000 mg/kg. En modelos murinos de inmunosupresión, hemos demostrado la capacidad de Fracción D de Maitake de restaurar poblaciones linfocitarias específicas en ganglios linfáticos, entre ellos granulocitos polimorfonucleares y LT/NK, además de inducir procesos de maduración celular. Comparado con quimioterapia, Fracción D de Maitake aumenta la sobrevida total de los animales y reduce la malignidad de los tumores mamarios. Estos sorprendentes hallazgos nos permiten suponer que el componente bioactivo de Maitake podría llegar a emplearse como agente preventivo de tumorigénesis mamaria en una población de riesgo, induciendo supresión tumoral, bloqueando la invasividad y la metástasis, esto es, las principales causas de muerte por cáncer mamario. / Breast cancer is the most frequent neoplasia in the world and one of the main causes of death among cancer women. Some of the conventional treatments for cancer are chemotherapy or radiotherapy, knowing that both generate very toxic side effects, since they usually affect all cells in active division (healthy or tumoral cells). Therefore, specific treatments are necessary, with therapies aimed at the molecular characteristics of the tumor and its microenvironment. An approach to this could be the search for natural compounds with immuno-potentiating capacity and selective toxicity on tumor cells. Recently, immunomodulatory and antitumor activities have been discovered in various fungi. Among them, β-glucans of Fraction D of Grifola frondosa (Maitake) are capable of generating innate and adaptive immune responses, exerting antitumor effects. The reported therapeutic benefits of treatment of breast tumorigenesis with D Fraction of Maitake require to deepen pharmacological and toxicological aspects of its bioactive molecules, in order to guarantee innocuousness and efficacy in the administration to a patient. Therefore, the trials proposed in this work aimed to elucidate toxicological, pharmacodynamic and pharmacokinetic aspects of ß-glucans from D Fraction. In this way, we hope to make a significant contribution to the pharmacological knowledge of these bioactive compounds by promoting an immunotherapeutic and antitumor strategy novel agent, aimed at the prevention of mammary carcinogenesis through the administration of natural compounds. Through our work presented here, we have demonstrated in in vitro cultures that D Fraction induces apoptotic death of mammary tumor cells both murine LM3 (independent hormone) and human MCF-7 (hormone dependent), while not affecting the viability of normal MCF-10F mammary cells. We found that the ß-glucans in the extract act through Dectin-1 receptors to induce tumor apoptosis, and are also capable of modifying the expression profile of a wide variety of genes with diverse functions, including apoptosis-specific genes associated with the suppression of the mammary tumor phenotype, and genes associated to cellular processes whose deregulation is linked to the development and tumor progression. Our in vivo pharmacokinetic studies on oral and intravenous administration in murine models showed that D Fraction presents more than one higher peak in the plasma concentration. It has a higher volume of tissue distribution and is captured mainly at the gastrointestinal level. Despite its voluminous structure and high molecular weight, it is able to reach the brain.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-10-20T17:56:33Z No. of bitstreams: 2 Dissertação - Estefânia Viano da Silva - 2014.pdf: 4645592 bytes, checksum: f3321dacb1ccfd2f2b017d08f8e3b578 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-10-20T17:58:09Z (GMT) No. of bitstreams: 2 Dissertação - Estefânia Viano da Silva - 2014.pdf: 4645592 bytes, checksum: f3321dacb1ccfd2f2b017d08f8e3b578 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-20T17:58:09Z (GMT). No. of bitstreams: 2 Dissertação - Estefânia Viano da Silva - 2014.pdf: 4645592 bytes, checksum: f3321dacb1ccfd2f2b017d08f8e3b578 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-06-26 / The mushrooms have been used as food and medicine for thousands of years. Among them, Grifola frondosa (“Maitake”) may be on the most versatile and promising medicinal mushrooms for use as a dietary supplement. Besides the high nutritional value, they are a good source of compounds such as carbohydrates that can act as biological response modifiers. In this work, β-D-glucans (PSF2-GfM and MRSF2K-GfM fractions) and heteropolysaccharides unusual in the literature (MEPF3CW-GfM and PF2K-GfM fractions) were isolated from the mycelium, grown in solid culture, of the G. frondosa, by successive aqueous and alkaline extractions, followed by fractionation through freeze-thawing, precipitation of soluble material with a Fehling solution, and dialysis using a membrane with an exclusion limit of 1000 kDa. The chemical structures were established based on monossacharide composition, periodate oxidation, methylation analysis, HPSEC-MALLS and NMR studies. The branched β-D-glucans (GLC-GfM) found were similar to those previously described for the fungus, which contains a (13)- linked β-Glcp main-chain, substituted at O-6 by single-unit -Glcp side-chains, on the average of one to every third residues of the backbone, but with different molar masses and water solubility. In adittion, novel heteropolymers were obtained. One was a fucomannogalactan (FMG-GfM), with a molar mass of 175 x 103 g mol-1, was shown to have a main chain of (1→6)-linked α-D-Galp and 3-O-Me-α-DGalp, both of which are partially substituted at O-2, principally, by 3-O-α-D-Manp-α-LFucp groups. The other was a fucoxylomannan (FXM-GfM) (Mw 202 x 103 g.mol-1), which consisted of backbone of (13)-linked α-D-Manp units, totally substituted at O-4 mainly by 4-O-α-L-Fucp-β-D-Xylp disaccharide. Thus, the polymers obtained from Grifola frondosa may could be good candidates for evaluation of its biological effect, considering the results obtained for others similar mushrooms polysaccharides. / Os cogumelos têm sido usados como alimentos e remédios por milhares de anos. Entre eles, o “Maitake” (Grifola frondosa) pode ser um dos cogumelos medicinais mais versáteis e promissores para o uso como um suplemento dietético. Além do valor nutricional elevado, eles são uma boa fonte de compostos, como os carboidratos, que podem agir como modificadores de resposta biológica. Neste trabalho, foram isolados do micélio (cultivado em meio sólido) de G. frondosa as β-D-glucanas (frações PSF2KGfM e MRSF2K-GfM) e heteropolissacarídeos (frações MePF3CW-GfM e PF2K-GfM) não comumente encontrados na literatura, por sucessivas extrações aquosas e alcalinas, seguido por fracionamento através do processo de congelamento/degelo, precipitação das frações solúveis em água com solução de Fehling e diálise em membranas com limite de exclusão de 1000 kDa. A estrutura química foi determinada através das análises de composição mossacarídica, oxidação com periodato de sódio, metilação, HPSEC-MALLS e RMN. As β-D-glucanas (GLC) isoladas foram similares àquelas previamente descritas para este fungo, as quais contém uma cadeia principal formada por unidades de 3-O-β-D-Glcp, podendo ser substituídas em O-6 por terminais não redutores de β-Glcp (1 ramificação a cada três unidades da cadeia principal), distinguindo-as quanto à solubilidade em água e tamanho (massa molar). Além destas, foram obtidos novos heteropolímeros. Um deles foi uma fucomanogalactana (FMGGfM), com uma massa molar de 175 x 103 g mol-1, a qual possui um core constituído por unidades de 6-O-α-D-Galp e 6-O-(3-O-Me-α-D-Galp), sendo ambas parcialmente substituídas em O-2 por 3-O-α-D-Manp-α-L-Fucp. O outro heteropolissacarídeo isolado consiste em uma fucoxilomanana (FXM-GfM) (Mw 202 x 103 g.mol-1) formada por unidades de α-D-Manp unidas por ligações glicosídicas do tipo (13) as quais se encontram ramificadas em O-4 principalmente pelo dissacarídeo 4-O-α-L-Fucp-β-DXylp. Considerando os efeitos terapêuticos apresentados por moléculas similares descritas para macrofungos, estes podem ser bons candidatos para avaliação do efeito biológico.