Submitted by PPG Biologia Celular e Molecular (bcm@pucrs.br) on 2018-04-17T11:40:30Z No. of bitstreams: 1 KELLY_GOULART_LIMA_TES.pdf: 13016256 bytes, checksum: b2a78492cbc6e285501d0eed5538a8ee (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2018-05-04T16:48:04Z (GMT) No. of bitstreams: 1 KELLY_GOULART_LIMA_TES.pdf: 13016256 bytes, checksum: b2a78492cbc6e285501d0eed5538a8ee (MD5) / Made available in DSpace on 2018-05-04T16:56:22Z (GMT). No. of bitstreams: 1 KELLY_GOULART_LIMA_TES.pdf: 13016256 bytes, checksum: b2a78492cbc6e285501d0eed5538a8ee (MD5) Previous issue date: 2018-03-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Octyl gallate (OG) is an antioxidant used in the food, cosmetic and medications industries that has shown antitumor effect on cell lineage of leukemia, melanoma and B cell lymphoma, as well as on animal model of pulmonary metastasis. Hepatocellular carcinoma (HC) is the main primary liver cancer affecting the world's population. Although surgical resection, ablation and liver transplantation are curative options, few patients are eligible for these therapies. The application of these therapeutic options is indicated only in the early stages of the disease and unfortunately most patients are diagnosed at advanced stage. In addition, there are reports in the literature of resistance to the only drug approved for systemic treatment, sorafenibe. In this study, we investigated the effect of OG on cell proliferation and lipidic metabolism in hepatocellular carcinoma HepG2 cells. Moreover, we developed a protocol for the quantitative evaluation of lipid droplets. We report, for the first time, that treatment with OG for 24 h inhibited HepG2 cell growth by decreasing mitochondrial activity and mass, which led to the reduction of ATP levels. This reduction in the energy supply triggered a decrease in Ki67 protein expression, leading to cycle arrest in S phase. In addition, the use of two treatments with OG with interval 24 hours induced loss of mitochondrial functionality and apoptosis without inducing resistance. These results showed that OG targets the mitochondria and is a candidate for new research on therapies for CH. We also report, for the first time, the effect of OG on lipidic metabolism, since our results showed that OG was able to increase the amount of lipids, triglyceride levels and the area of lipid droplets without involving the mTOR/SREBP-1c signaling pathway or modification of PPAR-? and PPAR-? gene expression. As the ability of OG to inhibit mitochondrial activity and induce apoptosis is known, it is strongly suggested that reduction of mitochondrial fatty acid b-oxidation is involved in the OG mechanism in the accumulation of lipids. We also describe, for the first time, a protocol for the quantitative evaluation of lipid droplets using confocal laser scanning microscopy that compared to conventional fluorescence microscopy, provided great gain in the quality of the images. / O galato de octila (GO) ? um antioxidante utilizado na ind?stria de alimentos, cosm?ticos e de medicamentos que tem mostrado efeito antitumoral em linhagem celular de leucemia, melanoma e linfoma de c?lulas B, assim como em modelo animal de met?stase pulmonar. O Carcinoma hepatocelular (CH) ? o principal c?ncer prim?rio hep?tico que afeta a popula??o mundial. Embora a ressec??o cir?rgica, a abla??o e o transplante hep?tico sejam considerados terapias curativas, poucos pacientes s?o eleg?veis. A aplica??o dessas op??es terap?uticas ? indicada somente para est?gios iniciais da doen?a e infelizmente a maioria dos pacientes ? diagnosticado em est?gio avan?ado. Al?m disso, existem relatos na literatura de resist?ncia ? ?nica droga aprovada para tratamento sist?mico, o sorafenibe. Nesse estudo, n?s investigamos o efeito do GO sobre a prolifera??o celular e metabolismo lip?dico nas c?lulas de carcinoma hepatocelular HepG2. Al?m disso, desenvolvemos um protocolo para avalia??o quantitativa de gotas lip?dicas. N?s reportamos, pela primeira vez, que o tratamento com GO por 24 horas inibiu a prolifera??o das c?lulas HepG2 por reduzir a atividade e massa mitocondrial, que levou ? redu??o dos n?veis de ATP. Essa redu??o no fornecimento de energia desencadeou a diminui??o na express?o da prote?na Ki67, levando ? parada do ciclo celular em fase S. Al?m disso, o uso de dois tratamentos com GO com intervalo de 24 horas induziu perda da funcionalidade mitocondrial e apoptose, sem induzir resist?ncia. Esses resultados mostraram que o GO tem como alvo a mitoc?ndria, sendo um candidato para novas pesquisas sobre terapias para o CH. Reportamos tamb?m, pela primeira vez, o efeito do GO sobre o metabolismo lip?dico, visto que nossos resultados mostraram que o composto foi capaz de aumentar a quantidade de lip?deos, os n?veis de triglicer?deos e a ?rea de gotas lip?dicas, sem envolver a via de sinaliza??o mTOR/SREBP-1c ou a modifica??o da express?o dos genes PPAR-? e PPAR-?. Uma vez que a capacidade do GO em inibir a atividade mitocondrial e induzir a apoptose ? conhecida, ? fortemente sugerido que a redu??o da ?-oxida??o mitocondrial de ?cidos graxos esteja envolvida no mecanismo do GO no ac?mulo de lip?deos. Descrevemos tamb?m, pela primeira vez, um protocolo para avalia??o quantitativa de gotas lip?dicas usando microscopia confocal de varredura a laser que comparado ? microscopia de fluoresc?ncia convencional, proporcionou grande ganho na qualidade das imagens.