No description available.

No description available.

Cancer cells utilise glycolysis to produce lactate, even in the presence of sufficient levels of oxygen. Excess lactate is removed from cancer cells by MCT1 and MCT4, to prevent intracellular acidosis, apoptosis and to aid the continuous glycolytic flux. MCT1 and MCT4 are over-expressed in many types of human cancers, which correlates with reduced overall survival and increased treatment resistance. The potential role of MCT1 and MCT4 in two EOC cell lines (Skov3 and OV90) was investigated in this study. MCT1 was expressed at similar levels in Skov3 and OV90 cells. Therefore, stable cell lines over-expressing MCT1 were produced using both cell lines. MCT4 was expressed at high levels in Skov3 cells, but very low levels in OV90 cells. Therefore, a stable cell line with MCT4 silencing under the inducible control of doxycycline was produced using Skov3 cells, and a stable cell line to over-express MCT4 was produced using OV90 cells. The consequences of these genetic modifications on the metabolic phenotype, metastatic abilities and the sensitivity of cell lines to treatment with Carboplatin and Paclitaxel, were assessed in normoxia and 1 % hypoxia and 0.1 % hypoxia. Over-expressing MCT1 in Skov3 cells, had no effect on their metabolic phenotype or the sensitivity to treatment with Carboplatin and Paclitaxel. However, over-expressing MCT1 in Skov3 cells significantly enhanced their metastatic abilities, which correlated with reduced focal adhesion size. Silencing MCT4 in Skov3 cells, had no effect on the use of glycolysis, sensitivity to treatment with Carboplatin and Paclitaxel, or their metastatic abilities. However, following MCT4 silencing there was a significant increase in the levels of intracellular ROS. Over-expressing MCT1 in OV90 cells, had no effect on lactate levels or intracellular ROS. However, there was a significant reduction in both their glycolytic activity and mitochondrial mass. Furthermore, over-expressing MCT1 in OV90 cells, increased their resistance to treatment with Paclitaxel, which correlated with increased Pgp and LDHA expression. Over-expressing MCT4 in OV90 cells, caused an increase in the use of glycolysis and increased cell survival in hypoxia. There was also a significant enhancement in the metastatic abilities of these cells following the over- expression of MCT4, which correlated with reduced focal adhesion size. Furthermore, over-expressing MCT4 in OV90 cells, increased their resistance to treatment with Paclitaxel, which correlated with an increase in the expression of Pgp and LDHA.In summary, the findings of this study revealed that MCT1 and MCT4 play a significant role in the biological function of Skov3 and OV90 cells. High expression levels of MCT4 correlated with an increase in glycolysis and cell survival in hypoxia. Whereas high expression levels of MCT1 and MCT4 in correlated with an increase in the metastatic abilities, as well as with Paclitaxel resistance and increased Pgp expression.

The study of cancer plays an important role in modern medical science. Over the years, a lot has been learnt about the properties and treatment of cancer cells. Despite the remarkable progress made in understanding the genesis of cancer, the work so far has had very little impact in the clinic especially the design of new and improved drugs. Platinum-based drugs such as cis-diamminedichloroplatinum(II) and its anolgue, carboplatin, are the most effective chemotherapeutic agents used in the treatment of testicular, ovarian, bladder and lung cancers. Nevertheless, the emergence of toxic side-effects compromises its clinical effectiveness. It is generally agreed that most of the toxic effects of platinum-based drugs arise from their lack of selectivity. This thesis reports on the development of new platinum(II) complexes bound to carrier molecules with the hope of obtaining compounds which display the cytotoxic effects only in tumour tissue. In addition, some information is included about what is known about the causes of cancer, how it kills and the current methods of treatment / Doctor of Philosophy (PhD)

Ovarian cancer remains the deadliest gynecologic malignancy. Current treatment has low efficacy in the long term, leading to low 5-year survival rates of 20-40%. Treatment-free periods between cycles of chemotherapy are accepted in standard treatment. These periods lead to accelerated tumor cell proliferation, angiogenesis and drug resistance development. Studies presented herein show advantages of continuous carboplatin dosing schedule over conventional intermittent regimen, both administered intraperitoneally. Continuous carboplatin therapy blocked acceleration of cell proliferation observed during treatment-free period of intermittent therapy. Moreover, continuous carboplatin led to 57% inhibition of SKOV3 tumors grown intraperitoneally in SCID mice, a significant advantage over the 33% tumor suppression observed with intermittent carboplatin. Immunohistochemical analysis revealed continuous carboplatin led to greater tumor cell death while suppressing tumor cell proliferation and angiogenesis when compared to intermittent administration. These results show that the suppression of tumor growth with carboplatin can be enhanced by the elimination of treatment free periods.

Ovarian cancer remains the deadliest gynecologic malignancy. Current treatment has low efficacy in the long term, leading to low 5-year survival rates of 20-40%. Treatment-free periods between cycles of chemotherapy are accepted in standard treatment. These periods lead to accelerated tumor cell proliferation, angiogenesis and drug resistance development. Studies presented herein show advantages of continuous carboplatin dosing schedule over conventional intermittent regimen, both administered intraperitoneally. Continuous carboplatin therapy blocked acceleration of cell proliferation observed during treatment-free period of intermittent therapy. Moreover, continuous carboplatin led to 57% inhibition of SKOV3 tumors grown intraperitoneally in SCID mice, a significant advantage over the 33% tumor suppression observed with intermittent carboplatin. Immunohistochemical analysis revealed continuous carboplatin led to greater tumor cell death while suppressing tumor cell proliferation and angiogenesis when compared to intermittent administration. These results show that the suppression of tumor growth with carboplatin can be enhanced by the elimination of treatment free periods.

No description available.

Nanographene oxide particles (NGO) were produced via oxidative exfoliation of graphite. Three different sizes of NGO (300 nm, 200 nm and 100 nm) have been separated by using probe sonication and sucrose density gradient centrifugation. There is great interest in functionalized NGO as a nanocarrier for in vitro and in vivo drug delivery, in order to improve dispersibility and stability of the nanocarrier platforms in physiological media. In this study, the NGO particles were covalently functionalized with zero generation polyamidoamide (PAMAM-G0) and with gelatin via noncovalent interaction. Spectroscopic techniques have been used to discriminate the chemical states of NGO prior and after functionalization. The X-ray photoelectron spectroscopy (XPS) revealed a clear change in the chemical state of NGO after functionalization, for both covalent and noncovalent approaches. Raman spectroscopy gave obvious insight after oxidation of graphite and functionalization of NGO particles depending on the variation of intensity ratios between D, G and 2D bands. The Fourier transform infrared spectroscopy (FTIR) exhibited the presence of oxygen containing functional groups distributed onto graphene sheets after oxidation of graphite. Furthermore, the FTIR is complementary with the XPS which performed a strong reduction in the oxygen contents after functionalization. UV visible spectroscopy was used to understand the binding capacity of gelatin coated NGO particles. The Microscopy tools, scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used to estimate the dimensions of NGO particles (thickness and lateral width). The nanohybrid systems (NGO-PAMAM and Gelatin-NGO) loaded with carboplatin (CP) were sought for anticancer activity investigation in HeLa and neuroblastoma cancer cells respectively. Mesenchymal stem cells (hMSCs) were used as a model of normal cells. On HeLa cells, the pristine NGO particles with average widths of 200 nm and 300 nm showed a cytotoxic effect at low (50 g.ml−1) and high (100 g.ml−1) concentrations. While the pristine NGO sample with an average width of 100 nm revealed no significant cytotoxicity at 50 g.ml−1, and only recorded a 10% level at 100 g.ml−1. The mesenchymal stem cells showed less than 35% viability for all size distributions. After functionalization with PAMAM, the carrier was found to be able to deliver carboplatin to the cancer cells, by enhancing the drug anticancer efficiency. Moreover, the carboplatin loaded NGO carrier shows no significant effect on the viability of hMSCs even at high concentration (100 g.ml−1). On neuroblastoma cells, the cell viability assay validated gelatin-NGO nanohybrids as a useful nanocarrier for CP release and delivery, without obvious signs of toxicity. The nano-sized NGO (200 nm and 300 nm) did not enable CP to kill the cancer cells efficiently, whilst the CP loaded gelatin-NGO 100 nm resulted in a synergistic activity through increasing the local concentration of CP inside the cancer cells.

Existe um grande interesse das indústrias farmacêuticas em encontrar um tratamento adequado para os pacientes com câncer que apresentaram resistência aos medicamentos comumente utilizados para o combate dessa neoplasia. Sendo assim, se faz necessário a busca de novos marcadores genéticos que estejam associados à predisposição do paciente a reagir ao efeito da droga de maneira diferente do esperado. Para isso, vários estudos vêm sendo desenvolvidos, baseados nos medicamentos anticancerígenos. Entre esses medicamentos podemos destacar os agentes quimioterápicos a base de platina, como a carboplatina, cisplatina, oxaliplatina e a nedaplatina, que agem eliminando as células cancerosas através da formação de adutos nas bases de purina do DNA nuclear e a rebecamicina, um antitumoral que possui a capacidade de inibir a ação catalítica das topoisomerases I, ainda em teste clínico. Desse modo, este estudo teve a perspectiva de encontrar mutantes de leveduras resistentes a carboplatina e análogos de rebecamicina. Como resultado, identificamos 19 genes associados à resistência a carboplatina, sendo que 6 deles possuem genes ortólogos em humanos associados principalmente ao mecanismo de reparo de DNA e ao transporte celular. Foram também identificadas 9 linhagens que estavam associadas a sensibilidade a carboplatina sendo que 3 delas possuem deleções em genes com ortólogos humanos, que estão associados ao transporte endossomal, ao ribossomo e ao bloqueio do ciclo celular na fase G1. Na busca por um novo composto antitumoral derivado de rebecamicina, identificamos Reb C como um análogo promissor, já que apresentou 9 genes associados a resistência, dos quais 2 deles possuem ortólogos humanos relacionados ao ribossomo e ao proteassoma / There is a strong interest from pharmaceutical companies in finding an appropriate treatment for patients with cancer who had resistance to drugs commonly used to fight this disease. Therefore, it is necessary to search for new genetic markers that are associated with the patient\'s predisposition to react to the drug differently than expected. Aiming this, several studies have been developed based on anticancer drugs. Among these drugs can be highlighted the chemotherapeutic agents based on platinum, such as carboplatin, cisplatin, oxaliplatin and nedaplatin, which act by eliminating cancer cells through the formation of adducts with the purine bases of nuclear DNA and the rebeccamycin, an antitumor that has the ability to inhibit the catalytic action of topoisomerase I, still in clinical trial. This study aimed to find yeast resistant mutants to carboplatin and rebeccamycin analogs. As a result, we identified 19 genes associated with resistance to carboplatin, 6 of them presenting orthologous genes in humans, which are mainly associated to the mechanism of DNA repair and to cellular transport. 9 strains were also identified which are associated with carboplatin sensitivity, 3 possessing their orthologous in humans associated with endosomal transport, ribosome and cell cycle arrest in the G1 phase. In a search for a new antitumor compound derived from rebeccamycin, we identified the Reb C analog as promising, since it featured nine genes associated with resistance to it, among 2 of them have human counterparts related to the ribosome and the proteasome.

Existe um grande interesse das indústrias farmacêuticas em encontrar um tratamento adequado para os pacientes com câncer que apresentaram resistência aos medicamentos comumente utilizados para o combate dessa neoplasia. Sendo assim, se faz necessário a busca de novos marcadores genéticos que estejam associados à predisposição do paciente a reagir ao efeito da droga de maneira diferente do esperado. Para isso, vários estudos vêm sendo desenvolvidos, baseados nos medicamentos anticancerígenos. Entre esses medicamentos podemos destacar os agentes quimioterápicos a base de platina, como a carboplatina, cisplatina, oxaliplatina e a nedaplatina, que agem eliminando as células cancerosas através da formação de adutos nas bases de purina do DNA nuclear e a rebecamicina, um antitumoral que possui a capacidade de inibir a ação catalítica das topoisomerases I, ainda em teste clínico. Desse modo, este estudo teve a perspectiva de encontrar mutantes de leveduras resistentes a carboplatina e análogos de rebecamicina. Como resultado, identificamos 19 genes associados à resistência a carboplatina, sendo que 6 deles possuem genes ortólogos em humanos associados principalmente ao mecanismo de reparo de DNA e ao transporte celular. Foram também identificadas 9 linhagens que estavam associadas a sensibilidade a carboplatina sendo que 3 delas possuem deleções em genes com ortólogos humanos, que estão associados ao transporte endossomal, ao ribossomo e ao bloqueio do ciclo celular na fase G1. Na busca por um novo composto antitumoral derivado de rebecamicina, identificamos Reb C como um análogo promissor, já que apresentou 9 genes associados a resistência, dos quais 2 deles possuem ortólogos humanos relacionados ao ribossomo e ao proteassoma / There is a strong interest from pharmaceutical companies in finding an appropriate treatment for patients with cancer who had resistance to drugs commonly used to fight this disease. Therefore, it is necessary to search for new genetic markers that are associated with the patient\'s predisposition to react to the drug differently than expected. Aiming this, several studies have been developed based on anticancer drugs. Among these drugs can be highlighted the chemotherapeutic agents based on platinum, such as carboplatin, cisplatin, oxaliplatin and nedaplatin, which act by eliminating cancer cells through the formation of adducts with the purine bases of nuclear DNA and the rebeccamycin, an antitumor that has the ability to inhibit the catalytic action of topoisomerase I, still in clinical trial. This study aimed to find yeast resistant mutants to carboplatin and rebeccamycin analogs. As a result, we identified 19 genes associated with resistance to carboplatin, 6 of them presenting orthologous genes in humans, which are mainly associated to the mechanism of DNA repair and to cellular transport. 9 strains were also identified which are associated with carboplatin sensitivity, 3 possessing their orthologous in humans associated with endosomal transport, ribosome and cell cycle arrest in the G1 phase. In a search for a new antitumor compound derived from rebeccamycin, we identified the Reb C analog as promising, since it featured nine genes associated with resistance to it, among 2 of them have human counterparts related to the ribosome and the proteasome.