Thesis (Ph.D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed on June 24, 2009). Includes bibliographical references.

Thesis (Ph.D.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 139 pages. Includes Vita. Includes bibliographical references.

Made available in DSpace on 2015-12-06T23:44:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2006 / Objetivo: avaliar as alterações morfológicas e imuno-histoquímicas de músculo esquelético (sóleo) de ratos submetidos à isquemia e reperfusão sob a ação da pentoxifilina. Métodos: Sessenta ratos foram submetidos à isquemia do membro posterior por seis horas pelo clampeamento da artéria ilíaca comum esquerda. Após reperfusão os animais do grupo A (n=30) foram observados por quatro horas e o grupo B(n=30) por vinte e quatro horas. Seis animais sem isquemia e sem pentoxifilina (PTX) constituíram o grupo simulado. A PTX não foi aplicada nos grupos A1(n=10) e B1(n=10), foi aplicada no início do período de reperfusão em A2(n=10) e B2(n=10), foi aplicada no início da isquemia e início da reperfusão em A3(n=10) e B3(n=10). O músculo sóleo foi coletado no final do período de observação de cada grupo e processado histologicamente para a avaliação à microscopia óptica dos parâmetros de dissociação de fibras (edema intersticial), infiltração intersticial de leucócitos e necrose. Pela coloração de imuno-histoquímica avaliou-se a apoptose pela expressão da caspase-3 em neutrófilos das áreas perivasculares e perinucleares. Foram aplicados os testes não-paramétricos Kruskall-Wallis e Mann-Whitney (p≤0,05). Resultados: Não houve expressão de necrose em nenhum dos períodos estudados. As alterações histológicas e de imuno-histoquímica foram mais intensas no grupo B1 com médias de escore do edema de 2,57 ± 0,13; infiltrado leucocitário de 2,05 ± 0,10; e a expressão da caspase-3 na área perivascular de 4,30± 0,79; e menos intensas no grupo A3 com respectivas médias de 0,77± 0,08; 0,92±0,10; 0,76± 0,16; 0,67± 0,15 (p < 0,05). A caspase-3 mostrou-se mais expressiva no grupo B1 na área perivascular com média de 4,30± 0,79 quando comparado com o grupo B1 na área perinuclear com média de 0,91± 0,32. Conclusões: As lesões de isquemia e reperfusão do músculo sóleo de ratos são mais intensas quando se observa por um maior tempo após a reperfusão e a pentoxifilina atenua estas lesões, sobretudo quando usada no início das fases de isquemia e de reperfusão. / Objective: to evaluate the morphologic and imunohistochemicals alterations of skeletal muscle (soleus) of rats submitted to the ischemia and reperfusion under the action of the pentoxifylline. Method: Sixty rats were submitted to the ischemia of the posterior hib by six hours by clamping the left common iliac artery. After reperfusion the animals of the group A (n=30) were observed by four hours and the group B (n=30) for twenty-four hours. Six animals without ischemia and without pentoxifylline (PTX) constituted the sham group. PTX was not applied in the groups A1 (n=10) and B1(n=10), it was applied in the initial of the reperfusion period A2(n=10) and B2(n=10), it was applied in initial of the ischemia and in the initial of the reperfusion in the groups A3(n=10) and B3(n=10). The muscle soleus was collected in the end of the period of observation of each group and processed for the evaluation to the optical microscopy of the parameters of dissociation of fibers (interstitial edema), interstitial infiltration of leukocytes and necrosis. For the imunohistochemical coloration it evaluated the apoptosis for the expression of the caspase-3 on neutrophils in perivascular and perinuclear areas. They were applied the no-parametric tests Kruskall-Wallis and Mann-Whitney (p≤0.05). Results: There was no expression of muscle necrosis in all of the groups. The histological and imunohistochemicals alterations were more intense in the group B1 with averages of score of the edema 2.57 ± 0.13; spread of leukocytes 2.05 ± 0.10; and the expression of the caspase-3 in the perivascular area 4.30± 0.79; and less intense in the group A3 with respective averages 0.77± 0.08; 0.92±0.10; 0,76± 0.16; 0.67± 0,15 with. The caspase-3 was shown more expressive in the group B1 of the perivascular area with average 4.30± 0.79 when compared with the group B1 of the perinuclear area with average 0.91± 0.32. Conclusions: The ischemia lesions and reperfusion of the muscle soleus of rats are more intense when it is observed a larger time after reperfusion and the pentoxifylline lessens these lesions, above all when used in the beginning of the ischemia and of reperfusion phases. / BV UNIFESP: Teses e dissertações

Une dysfonction olfactive et une altération de la neurogenèse sont observées dans plusieurs maladies neurodégénératives, y compris la maladie de Huntington (MH). Ce déficit est un symptôme précoce de la MH et est en corrélation avec le déclin de la performance cognitive globale, la dépression et la dégénérescence des régions olfactives dans le cerveau. La dysfonction olfactive dans les maladies neurodégénératives est souvent accompagnée par des anomalies structurelles de l’épithélium olfactif, du bulbe olfactif (BO) et du cortex olfactif chez l’humain. En dépit de preuves claires démontrant la dysfonction olfactive chez les patients de la MH l'information disponible est limitée dans des modèles murins et les mécanismes sous-jacents ne sont pas connus. Une diminution du volume et du compte neuronale dans le PC est observée dans les souris YAC128 vs le type sauvage (WT) âgée (12 mois). Nous avons également examiné les comportements lors d'exposition à des odeurs sociales et non sociales chez des souris en utilisant le test habituation. Une habituation aux odeurs tend à être observé dans les souris YAC128 de 1 mois vs WT se traduisant par une tendance de l’augmentation de la durée d’exploration des YAC128 vs WT lors de leurs 2e et 3e expositions à une odeur. Dans les couches glomérulaire et plexiforme externe, l’intensité réciproque du marquage de TH et de GFAP, marqueur de cellules gliales présente une tendance pour une augmentation dans les YAC128 comparativement au WT. Une tendance pour une diminution de Iba-1, marqueur de neuroinflammation, a aussi été observé dans la couche granulaire du BO de YAC128 âgée vs WT. Malgré une diminution de l’expression en ARNm de caspase-3 et -8, une augmentation de l'expression protéique de la proforme de caspase-8 et des formes actives de la caspase-8, -6 et -9 a été observés au stade présymptomatique dans des BO de YAC128 vs WT. De façon similaire aux YAC128, une atrophie du BO à 6 mois est remarqué dans le modèle de rat BACHD (lignées TG5 et TG9). Globalement, un niveau d’expression de la protéine huntington mutante (httm) est plus élevé dans les TG5. L’expression protéique dans les BO de la proforme des caspase-3, -6 et -8 sont supérieurs dans les TG9 lorsque comparés au TG5 et au WT. L’identification de marqueurs précoces pour la MH contribuera aux approches thérapeutiques et permettra de clarifier l'utilité des tests de la fonction olfactive dans les individus à risques de la MH.

Magister Pharmaceuticae - MPharm / Neurodegenerative diseases are multifactorial in nature, and taking the complex nature of these disorders into consideration, multi-target directed ligands may present as better options to treat these disorders than the classic ‘one molecule, one target’ approach. Neurotransmitter amines are catabolized by monoamine oxidase A and B (MAO-A and MAO-B), therefore they have been targeted for the treatment of neuropsychiatric and neurodegenerative diseases. Besides offering a potential antidepressant action in PD, MAO-A inhibitors may also provide a symptomatic benefit by reducing MAO-A-catalysed oxidation of dopamine. The oxidative deamination reaction catalyzed by MAO-B is one of the major catabolic pathways of dopamine in the brain. Inhibition of this enzyme leads to enhanced dopaminergic neurotransmission and are currently used in the symptomatic treatment of PD. Furthermore, MAO-B inhibitors may also exert neuroprotective effects by reducing the concentration of potentially hazardous by-products produced by MAO-B-catalysed dopamine oxidation. Apoptosis or programmed cell death occurs in a number of neurodegenerative disorders and it has been proven that inhibition of the executing enzyme, caspases-3, slows down or even stops apoptosis. Having this in mind we focused on the propargylamine function of selegiline and the fluorophenyl function of safinamide, because of their inherent monoamine oxidase inhibitory activities; and isatin as a non-peptide inhibitor of caspase-3. Therefore we attempted to design and synthesize multifunctional hybrid molecules acting simultaneously to halt the apoptotic neuronal breakdown process and eliminate the signs and symptoms of diseases such as PD. Seven novel compounds were successfully synthesized utilizing multistep processes. The synthesis of 5 chlorosulfonyl isatin was accomplished starting from the commercially available isatin in two steps, which were, sulfonation using tetramethylene sulfone and chlorination with POCl₃. Next 5-chlorosulfonyl isatin was conjugated to the fluorophenylamine derivative with the fluoro-function at either the ortho, meta or para position through a nucleophilic substitution reaction on the chlorosulfonyl position. The resultant compounds were coupled on the N position of the isatin function with propargyl bromide, using a microwave synthesis procedure, in a nucleophilic substitution reaction. The structures and purity were confirmed by nuclear magnetic resonance (NMR) and mass spectrometry (MS). In the biological evaluations recombinant human MAO-A, MAO-B and caspase 3 enzymatic assays were performed to determine the activity of the novel compounds at an enzymatic level. The inhibition percentages for these compounds were calculated and plotted against the logarithm 8 of the inhibitor concentrations to obtain a sigmoidal dose-response curve and consequently the IC50 value. The synthesized compounds showed inhibition of the MAO-A, MAO-B and caspase-3 enzymes at low to high micro molar concentrations. The role of the fluorophenylamine moiety in the synthesized compounds was significant for their multifunctional activity as shown by compounds 3 and 4 having good inhibitory activity towards MAO-A, MAO-B and also excellent inhibitory activity against caspase 3, making those ideal candidates for further lead compound development and multifunctional drug design. The introduction of the propargylamine moiety only increased the MAO-A inhibitory activity; this was shown by compounds 7, 8 and 9 which exhibit good MAO-A selectivity with low MAO-B and caspase-3 inhibitory activities.

Les caspases sont des protéases à cystéine, très étudiées dans la mort cellulaire par apoptose et impliquées dans de nombreux autres processus de survie tels que la prolifération, l’inflammation et la différenciation. Au cours de la différenciation des monocytes en macrophages induite par le M-CSF, les caspases sont activées au sein d’un complexe multiprotéique composé de FADD, de RIP1, de FLIP et de la caspase-8. Ce complexe se forme indépendamment des récepteurs de mort et en réponse à des vagues d’activation de PI3K/Akt successives d’amplitudes et de durées croissantes prenant naissance au niveau du récepteur au M-CSF. La caspase-8, activée dans ce complexe, active par clivage les caspases effectrices, qui clivent à leur tour des protéines dont la Nucléophosmine. La Nucléophosmine, aussi appelée NPM, B23, NO38 ou Numatrine est une protéine chaperonne nucléolaire effectuant la navette entre noyau et cytoplasme. Cette protéine est impliquée dans de nombreux processus dont la ribogenèse, la duplication du centrosome ou la régulation de la transcription. Au cours de ma thèse, j’ai décrit le clivage de NPM au cours de la différenciation macrophagique. NPM est clivée une première fois par les caspases sur le site NGKD213 puis pas la cathepsine B. La surexpression du fragment de clivage généré par les caspases inhibe la phagocytose de bactéries ainsi que la migration cellulaire, sans affecter la phagocytose des corps apoptotiques suggérant que le clivage de NPM par les caspase participe au maintien au repos des macrophages. La protéolyse de NPM est arrêtée lorsque les macrophages sont activés par des ligands des TLR comme les LPS. La forme native s’accumule et inhibe la synthèse de cytokines in vitro et in vivo. NPM est recrutée sur le promoteur de MCP-1 en présence de LPS suggérant une fonction transcriptionnelle de NPM. / Caspases are cystein proteases whose function in apoptosis has been largely explored. Caspases play a role in various other cellular processes, such as proliferation, inflammation or differentiation. During M-CSF-driven macrophagic differentiation, caspases are activated in a multimolecular complex, including FADD, RIP1, FLIP and caspase-8. This complex is death receptor independent and is linked to M-CSFR by successive PI3K/Akt waves of increasing amplitude and duration. Caspase-8 is activated in this complex, activates downstream effector caspases, which in turn cleaves cellular targets such as Nucleophosmin. Nucleophsomin (also called NPM, B23, NO38 or Numatrin) is a nucleolar chaperon protein that shuttles between nucleus and cytoplasm. This protein is involved in various cellular processes such as ribogenesis, centrosome duplication or transcription regulation. During my PhD, I described NPM cleavages during macrophagic differentiation. NPM is first cleaved by caspases at NGKD213 site and then by cathepsin B. Caspases-generated fragment overexpression inhibits bacteria phagoctosis and migration without affecting apoptotic bodies engulfment, suggesting that caspase-mediated NPM cleavage maintains macrophages at steady-state. NPM proteolysis is abrogated upon macrophage activation by TLR ligands such as LPS. Full-length NPM accumulates and inhibits cytokine synthesis in vitro and in vivo. NPM is recruited on MCP-1 promoter, suggesting a transcriptionnal function for NPM.

Inhibitors of apoptosis proteins (IAPs) are key intrinsic regulators of caspases-3 and -7. During ischemia, IAP-2 is upregulated dramatically, while the other IAPs show little or no change. To test whether IAP-2 prevents cardiac apoptosis and injury following ischemia/reperfusion, we generated a line of transgenic mice that carried a mouse IAP-2 transgene. High levels of mouse IAP-2 transcripts and 70 kDa IAP-2 were expressed in the hearts of transgenic mice, whereas IAP-1 and XIAP levels remained the same. Immunohistochemical studies revealed more intense staining of IAP-2 in the myocytes of transgenic mouse hearts. To assess the role of IAP-2 in I/R injury, the transgenic mice were subjected to ligation of the left descending anterior coronary artery ligation followed by reperfusion. The infarct sizes, expressed as the percentage of the area at risk, were significantly smaller in the transgenic mice than in the non-transgenic mice (30 ± 2% vs. 44 ± 2%, respectively, P < 0.05). This protection was accompanied by a decrease of the serum level of troponin I in the transgenic mice. IAP-2 transgenic hearts had significantly fewer TUNEL-positive cardiac cells, which indicated an attenuation of apoptosis. Our results demonstrate that overexpression of IAP-2 renders the heart more resistant to apoptosis and I/R injury.

Doxorubicin (Dox) is a chemotherapeutic agent that causes significant cardiotoxicity. We showed previously that Dox activates p53 and induces apoptosis in mouse hearts. This study was designed to elucidate the molecular events that lead to p53 stabilization, to examine the pathways involved in Dox-induced apoptosis, and to evaluate the effectiveness of pifithrin-α (PFT-α), a p53 inhibitor, in blocking apoptosis of rat H9c2 myoblasts. H9c2 cells that were exposed to 5 μM Dox had elevated levels of p53 and phosphorylated p53 at Ser15. Dox also triggered a transient activation of p38, p42/p44ERK, and p46/p54JNK MAP kinases. Caspase activity assays and Western blot analysis showed that H9c2 cells treated with Dox for 16 h had marked increase in the levels of caspases-2, -3, -8, -9, -12, Fas, and cleaved poly(ADP ribose) polymerase (PARP). There was a concomitant increase in p53 binding activity, cytochrome c release, and apoptosis. These results suggest that Dox can trigger intrinsic, extrinsic, and endoplasmic reticulum-associated apoptotic pathways. Pretreatment of cells with PFT-α followed by Dox administration attenuated Dox-induced increases in p53 levels and p53 binding activity and partially blocked the activation of p46/p54JNK and p42/p44ERK. PFT-α also led to decreased levels of caspases-2, -3, -8, -9, -12, Fas, PARP, cytochrome c release, and apoptosis. Our results suggest that p53 stabilization is a focal point of Dox-induced apoptosis and that PFT-α interferes with multiple steps of Dox-induced apoptosis.

P53 est un facteur de transcription qui se décline, chez l’homme, la souris ou la drosophile, en plusieurs isoformes. Chez la drosophile deux isoformes ont été caractérisées : la forme canonique Dp53 ; et une forme tronquée, D∆Np53, dont le domaine de transactivation est incomplet. Une des questions encore peu étudiée, concerne les mécanismes par lesquels p53 régule une grande variété de réponses cellulaires lors d’un stress. Pour répondre à cette question, nous avons étudié le rôle des isoformes de p53 dans la régulation de deux mécanismes antagoniste en lien avec la maladie de Parkinson (MP) : l’autophagie et l’apoptose en réponse à un stress délétère et un stress hormétique du système nerveux. Nous avons montré que les drosophiles portant une mutation nulle de p53 sont plus sensibles aux effets du paraquat (fort stress oxydant, modèle chimique de la maladie de Parkinson). En absence de p53, ce stress cause une forte inhibition de l’initiation et du flux de l’autophagie accompagné d’une augmentation des niveaux de caspases et de la mortalité. L’augmentation de la mortalité et des niveaux de caspases est similaire chez des mutants de l’autophagie pour lesquels le flux d’autophagie est constitutivement altéré. D’autre part, nous avons montré que les deux isoformes de p53 (Dp53 et D∆Np53) régulent différemment l’apoptose et l’autophagie dans les neurones photorécepteurs de drosophile : l’isoforme Dp53 présente un flux autophagique fonctionnel retardant la neurodégénérescence, tandis que, l’isoforme D∆Np53 inhibe le flux d’autophagie via l’activation des caspases Dcp1, Drice et Dronc. Enfin, nous avons établi un lien entre p53 et le stress du réticulum endoplasmique (RE). Dans un premier temps nous avons montré qu’un stress modéré du RE (pré-conditionnement) a un effet protecteur dépendant de l’activation de l’autophagie dans différents modèles de la MD. Ensuite, nous avons montré que les trois banches de la réponse au stress du RE (IRE1, Atf6 et PERK) sont impliquées dans cet effet protecteur. Enfin, nous avons montré que les drosophiles mutantes pour p53 perdent l’effet protecteur du pré-conditionnement. L’ensemble de nos résultats apporte de nouveaux éléments sur l’aspect multifonctionnel de p53 en réponse à un stress dans le système nerveux. Via ses multiples isoformes, p53 peut activer deux réponses antagonistes : l’autophagie et l’apoptose, permettant aux cellules une réponse flexible face à une situation de stress. La régulation de l’autophagie par p53 est protectrice et apparait comme étant une fonction ancestrale de p53. / P53 is a tumor suppressor gene, which has been showed to regulate several cellular pathways. Upon stress, p53 triggers multiple cellular pathways including DNA repair system, cell cycle arrest, apoptosis and autophagy. Thus, p53 is involved in both cellular protection and death pathways. One of the major questions is to understand how a single protein can promote so many different pathways. Here I address the putative role of p53 isoforms in the regulation of autophagy and apoptosis and their role in neuron survival in the context of Parkinson’s disease (PD). We show that p53 mutants are more susceptible to paraquat toxicity (chemical model of PD), indicating a protective role for p53. We also found that Atg8 mutant, which display an impaired autophagy, behave similarly to p53 upon paraquat treatment. In addition, we show that p53 is required for the activation of autophagy with a functional autophagy flux upon paraquat treatment and that lack of p53 or Atg8 results in an accumulation of activated caspases after paraquat treatment. Moreover, we found that autophagy and apoptosis were differentially regulated by different p53 isoforms. The Dp53 (p53B) isoform induced protective autophagy, whereas the D∆Np53 (p53A) isoform inhibited autophagy by activating the caspases Dronc, Drice and Dcp-1 in differentiated neurons. Our results demonstrate that a combination of the differential use of p53 isoforms and the antagonism between apoptosis and autophagy favors the generation of an appropriate p53 biological response to stress. In addition, we have defined in vitro and in vivo experimental conditions in which the activation of the Unfolded Protein Response (UPR) does not induce cell or organism lethality but rather promotes an adaptive response that protects from apoptotic stimuli. We show that this mild activation, known as ER-preconditioning is protective in several models of PD in an autophagy-dependent fashion. We showed that the three branches of the UPR are involved in the protective effect induced by ER-preconditioning. We then demonstrated that p53 is necessary to mediate the protection by ER-preconditioning suggesting that p53 may be a key factor in the integration of stress responses. Together our results reveal new aspects of the multi-functionality of p53. Activation of the antagonist pathways: autophagy and apoptosis by p53 isoforms, leads to flexible and adaptive response to stress. In addition, our results suggest that the regulation of autophagy by p53 is a ancestral protective function of p53.

Submitted by MARCIA ROVADOSCHI (marciar@unifra.br) on 2018-08-17T19:27:03Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ShayenneSchefferHomrich.pdf: 1706469 bytes, checksum: 48ab5f162c893018778d1ac573ca031d (MD5) / Made available in DSpace on 2018-08-17T19:27:03Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ShayenneSchefferHomrich.pdf: 1706469 bytes, checksum: 48ab5f162c893018778d1ac573ca031d (MD5) Previous issue date: 2017-03-28 / The Acute Promyelocytic Leukemia (APL), firstly described in 1957, is the most malignant type of acute leukemia. Currently, the knowledge of its pathophysiological mechanism at molecular levels became possible the development of efficient therapies making APL the most curable leukemia type. In this sense, APL is also used as a model on cancer advances, being the molecular treatment performed with all trans-retinoic acid (ATRA) that presents high efficiency at its control. However, several patients develop differentiation syndrome, as a side effect of this drug. In these terms, compared to another drugs, the cytotoxic antineoplastic agents present particular problems, as poor specificity, high toxicity and resistance susceptibility. An alternative strategy to decrease the ATRA cytotoxicity is the incorporation of this drug in polymer nanocapsules with oily core. In this work nanocapsules with lipid core containing ATRA (NA) were evaluated as their potential to inhibit cellular grow, to induce apoptosis, to interfere the cell cycle, and at APL cellular differentiation using NB4 cell line. Results showed that NA was able to overcome the cellular resistance to AL treatment, decreasing cell viability, inducing apoptosis, through BAX/BCL-2 gene expression, cell cycle arresting at G1 phase and cellular differentiation under 1.5 and 2.0 μM. Additionally, theses systems can contribute to increase the efficacy and reduce the toxicity due to the potential accumulation of nanoparticles at the tumor region due to increased vascular permeability of tumor vases. The ATRA incorporation in lipid nanocarriers is a interesting alternative to make possible its intravenous administration. Moreover, these systems present potential to drug accumulation at tumor tissue through a passive targeting called effect of permeability and increased retention. / A Leucemia Promielocítica Aguda (LPA), primeiramente descrita em 1957 é a forma mais maligna de leucemia aguda. Atualmente, o conhecimento dos seus mecanismos fisiopatológicos em nível molecular possibilitou o desenvolvimento de terapias eficazes fazendo com que a LPA seja a forma mais curável de leucemia. Por este motivo a LPA é também utilizada como modelo para os avanços no tratamento do câncer, sendo o tratamento molecular com ácido all-trans-retinoico (ATRA) o que apresenta alta eficiência no seu controle. Entretanto, inúmeros pacientes adquirem a Síndrome de Diferenciação, como efeito adverso a este medicamento. Diante disto, em comparação com outros fármacos, os antineoplásicos citotóxicos apresentam problemas únicos, como pobre especificidade, elevada toxicidade e susceptibilidade para induzir resistência. Uma estratégia para diminuir a citotoxicidade do ATRA é a incorporação do mesmo em nanocápsulas poliméricas com núcleo oleoso. Neste trabalho nanocápsulas de núcleo lipídico contendo ATRA (NA) foram avaliadas quanto ao seu potencial de inibir o crescimento, induzir a apoptose e interferir com o ciclo celular e na diferenciação de células de LPA, linhagem NB4. Os resultados demonstraram que a NA foi capaz de superar a resistência celular ao tratamento com AL, reduzindo a viabilidade celular, induzindo apoptose, pela expressão dos genes BAX/BCL-2, parada do ciclo celular em G1 e diferenciação celular nas concentrações de 1,5 e 2,0 μM. Adicionalmente, estes sistemas podem contribuir para o aumento da eficácia e redução da toxicidade devido ao potencial para acúmulo das nanopartículas na região tumoral graças à permeabilidade vascular aumentada dos vasos tumorais. A incorporação de ATRA em nanocarreadores lipídicos constitui uma alternativa interessante para viabilizar sua administração intravenosa. Além disso, estes sistemas apresentam potencial para acúmulo do fármaco na região tumoral, por meio de um direcionamento passivo chamado de efeito de permeabilidade e retenção aumentada.