Leung, Kin Chung. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 148-164). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Duzentos e quarenta e cinco neoplasias de glândula perianal de cães dos arquivos do Departamento de Patologia da FMVZ/ USP, de 1984 à 2004, foram revisadas histologicamente. A grande maioria dos casos (34%) foi classificada como adenoma moderadamente diferenciado, grupo II, em machos com mais de oito anos de idade o que reflete a dependência androgênica dessas neoplasias. A análise quantitativa da proliferação celular e apoptose nos diferentes tipos histológicos de neoplasias, hiperplasia e tecido normal dessas glândulas determinou um padrão paralelo de aumento de ambas as quantificações. Com os resultados do índice de crescimento ajustado obtivemos que, embora os carcinomas tenham um nível de proliferação celular muito maior que os adenomas (grupo I), esses têm um potencial de crescimento maior, levando-se em conta a apoptose. Investigamos, também, a expressão de Cx43, 26 e 32 nessas glândulas perianais com métodos imunoistoquímicos. A Cx 43 expressava-se em glândulas perianais normais, hiperplásicas, adenomas (grupo I) e adenomas moderadamente diferenciados. Nos adenomas pouco diferenciados (grupo II), a expressão estava reduzida e não se expressava nos carcinomas (grupo III). A Cx 26 acumulava-se no citoplasma nas glândulas normais, hiperplásicas, adenomas (grupo I) e adenomas moderadamente diferenciados (grupo II). Nos adenomas pouco diferenciados (grupo II), a expressão estava reduzida e, ausente, nos carcinomas. A Cx 32 não foi identificada em nenhum dos grupos (I, II e III) ou glândulas normais e hiperplásicas. Concluindo, Cx 43 e Cx26 são importantes para a homeostasia de glândula perianal normal, podendo estar associadas aos receptores de andrógenos presentes em suas células. Este foi o primeiro estudo mostrando a apoptose e sua influência na fase promocional da carcinogênese e, também, o primeiro estudo mostrando a expressão de Cx43, Cx 26 citoplasmática e ausência de expressão da Cx 32 em glândulas perianais normais, hiperplásicas e neoplásicas em cães / Two hundred and forty five neoplasms of the perianal glands of dogs from the archives of the Department of Pathology of the FMVZ/USP, 1984 to 2004, have been reviewed hystologically. Most of the cases (34%) were classified as moderately differentiated adenomas, group II, in males over 8 years of age, which showed an androgenic dependence of these neoplasms. The quantitative analysis of the cellular proliferation and apoptosis, in the different hystologic types of neoplasia, hyperplasia and normal tissue of these glands, determined a parallel pattern of increase in both quantifications. The values of the net growth index showed that although carcinomas have a much higher level of proliferation than adenomas (group I), these latter have a much higher potential of growth, taking into account the effect of the apoptosis. The occurrence of Cx 43, 26 and 32 in these perianal glands was also investigated by immunohystochemical methods. Cx 43 expression was present in normal, hyperplasic, adenomas (group I) and moderately differentiated adenomas perianal glands. In poorly differentiated adenomas (group II), the expression was reduced and was absent in carcinomas. Cx 26 was accumulated in the cytoplasm in normal, hyperplasic, adenomas (group I) and moderately differentiated adenomas glands. In poorly differentiated adenomas (group II), the expression was reduced and was absent in carcinomas. Cx 32 was not found in all groups (I, II, III), normal and hyperplasic glands. In conclusion, Cx 43 and Cx 26 are important for homeostasis of normal canine perianal glands, being able to be associated with the androgen receptors present in their cells. This was the first study showing the apoptosis and its influence on the promotional phase of carcinogenesis and, also, the first study showing the occurrence of Cx 43, cytoplasmatic Cx 26 and no expression of Cx 32 in normal, hyperplasic and neoplastic canine perianal glands

Orientador: Wellerson Rodrigo Scarano / Resumo: A capacidade de progressão do câncer de próstata para uma fase não-responsiva às terapias de privação androgênica traz à luz a importância do estudo de tratamentos adjuvantes. Pesquisas recentes apontam receptores estrogênicos como possíveis alvos terapêuticos em neoplasias, podendo ser modulados por fármacos como o Raloxifeno, atualmente utilizado na prevenção do câncer de mama e tratamento da osteoporose. Nesse contexto, o objetivo deste estudo foi avaliar os potenciais efeitos histoprotetores e antiproliferativos da terapia com Raloxifeno, durante a carcinogênese prostática. Para isso, 34 ratos Fisher 344 machos foram inoculados com o carcinógeno MNU (15 mg/kg) na cápsula dos lobos ventral e dorsolateral e receberam doses subcutâneas de cipionato de testosterona, duas vezes por semana, durante 220 dias, processo aqui denominado de Indução de Carcinogênese. Posteriormente, foram divididos em dois grupos experimentais para o período de Tratamento: grupo Raloxifeno, recebendo 10 mg/kg de peso corpóreo/dia de Raloxifeno diluído em 0,2 ml de óleo de milho durante 30 dias consecutivos; grupo Induzido, recebendo somente 0,2 ml de óleo de milho (veículo) durante 30 dias consecutivos. Outros 10 animais pertencentes ao grupo Controle receberam veículo duas vezes por semana por 220 dias para simular o processo de Indução e, posteriormente, durante 30 dias consecutivos para simular o período de Tratamento. Após a eutanásia, o sangue e as próstatas ventral e dorsolateral foram coletado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Prostate cancer ability to progress to a non-responsive phase to androgen deprivation therapy emphasizes the importance of study on adjuvant treatments. Recent research suggests estrogen receptors as possible therapeutic targets in neoplasias and they can be modulated by drugs such as Raloxifene, currently used in the prevention of breast cancer and treatment of osteoporosis. In this context, this study aimed to evaluate the histoprotective and antiproliferative potential effects of Raloxifene therapy during prostatic carcinogenesis. Thereunto, 34 male Fisher 344 rats were inoculated with the MNU carcinogen (15 mg / kg) in the ventral and dorsolateral lobe capsule and received subcutaneous doses of testosterone cypionate twice a week for 220 days. Subsequently, they were divided into two experimental groups: Raloxifene group, receiving 10 mg/kg of body weight/day of Raloxifene diluted in 0.2 ml of corn oil for 30 consecutive days; Induced group, receiving only 0.2 ml corn oil (vehicle) for 30 consecutive days. Another 10 animals belonging to the Control group received vehicle twice a week for 220 days to simulate the induction process and subsequently for 30 consecutive days to simulate the treatment period. After euthanasia, blood and the ventral and dorsolateral prostate lobes were collected for hormonal dosage, histopathological analysis of the lesions, quantification of mast cells, picrosirius (collagen fibers) and immunostaining for AR (androgen receptor), α-actin and Ki... (Complete abstract click electronic access below) / Doutor

Breast cancer is a heterogeneous disease with multiple phenotypes that specify both treatment options and prognosis. The Luminal A-type breast cancers, characterized by high levels of estrogen receptor (ER) expression and transcriptional activity, have a stable of hormone-related treatment options and a favorable prognosis. Recent efforts to identify mechanisms governing the Luminal A phenotype have identified transcription factor activator protein 2C (TFAP2C) as a critical regulator of both ER and ER-associated gene expression, making it a prime target for manipulation in breast cancer therapy. To that end, we sought to establish specific contributions of TFAP2C in both normal development and cancer progression, with the overarching hypothesis that TFAP2C is an integral transcription factor in maintaining a luminal differentiation and expression pattern in human breast cancer. To address this, we utilized several parallel approaches to identify potential TFAP2C-related contributions to carcinogenesis. In the first approach, we identified that tissue-specific abrogation of the mouse homolog TCFAP2C in mammary epithelium produced a reduction in luminal populations and a concomitant increase in basal populations, producing mild phenotypic alterations in gland structure. In the second, we stably manipulated TFAP2C expression in the established Luminal A model cell line MCF-7, establishing that TFAP2C loss promotes a loss of luminal differentiation characteristics and a gain of basal / mesenchymal traits, mirroring the results found in the mouse model. As a final approach, we examined the role of a TFAP2C target gene, manganese superoxide dismutase (MnSOD), in modulating redox biological and epigenetic parameters that may contribute to carcinogenesis. We found that loss of MnSOD in the murine liver, chosen because of its utility as a model system, promoted subtle changes in the redox buffering capacity and identified preliminary changes in the epigenome, suggesting that MnSOD modulation by TFAP2C could play a role in cancer development. Overall, these results further establish a role of TFAP2C in the genesis of Luminal A breast cancer, and serve as a foundation for more comprehensive future work evaluating specific contributions in carcinogenesis.

Environmental airborne benzene is a ubiquitous hazardous air pollutant whose emissions are generated from multiple sources, including industrial emissions, fuel station emissions, and automobile emissions. Chronic occupational exposures to elevated levels of benzene are known to be associated with leukemic cancers, in particular, acute myeloid leukemia (AML), though epidemiological evidence regarding environmental exposures and subsequent AML development is lacking. This investigation uses historical airborne monitoring data from six counties in the State of Florida to characterize the environmental cancer risk from airborne benzene concentrations using current Federal and State regulatory analysis methodology, and a comparative analysis based on occupational epidemiological evidence. Airborne benzene concentrations were collected from 24 air toxics monitoring stations in Broward, Duval, Orange, Miami-Dade, Hillsborough, and Pinellas counties. From the years 2003 - 2006, 3,794 air samples were collected using 8, 12, and 24 hr samples with sub-ambient pressure canister collectors consistent with EPA benzene methodological protocols 101 and 176. Mean benzene concentrations, by site, ranged from 0.18 - 3.58 ppb. Using risk analysis methodology consistent with the EPA and the Florida Department of Environmental Protection (FLDEP) the resulting cancer risk estimates ranged from 4.37 x 10-6 to 8.56 x 10-5, exceeding the FLDEP's acceptable cancer risk level, 1 x 10-6 for all monitoring sites. The cumulative lifetime exposures were calculated in ppm-years by site, ranging from 0.036 - 0.702 ppmyears. A comparative analysis with available epidemiological literature revealed that associations between benzene exposure and cancer outcomes were related to cumulative lifetime exposures in great excess of 1 ppm-years. The results of this investigation indicate that it is not reasonable to expect additional cancer outcomes in Florida residents as a result of airborne benzene exposures consistent with measured concentrations, despite the fact that all regulatory risk calculations exceed acceptable cancer risk levels in the State of Florida.

Exposure to polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene are important risk factors for cancer. Three UDP-glucuronosyltransferases, UGT1A9, UGT1A10, and UGT2B7, have been shown to play an important role in the phase II metabolism of carcinogenic metabolites of BaP. Because UGT1A9 and UGT2B7 are well-expressed in digestive tract tissues including liver and colon, it is possible that genetic variations in either enzyme may play an important role in colon cancer risk. However, UGT1A10 is extrahepatic and is expressed in the oral cavity and the larynx; therefore, genetic variations in this enzyme may play an important role in risk for orolaryngeal cancer. This study examined UGT1A9-, UGT1A10-, and UGT2B7-specific sequences for polymorphisms that play a role in cancer susceptibility. For the UGT1A9 gene, two missense polymorphisms at codons 167 (Val>Ala) and 183 (Cys>Gly) were identified. A previously-reported missense polymorphism was identified for the UGT2B7 gene. To assess the potential role of UGT1A10 variants as a risk factor for orolaryngeal cancer, PCR-RFLP was used to identify UGT1A10 genotypes in DNA specimens isolated from 115 African American newly-diagnosed orolaryngeal cancer cases and 115 non-cancer controls individually matched by age and race. A significantly decreased risk for orolaryngeal cancer was observed for subjects possessing one or more UGT1A10139Lys alleles as determined by crude analysis or after logistic regression analysis adjusting for age, sex, smoking and alcohol consumption. These results strongly suggest that the UGT1A10139Lys polymorphism may play an important protective role in risk for orolaryngeal cancer. To determine whether the change in amino acid sequence at codon 183 results in aberrant UGT1A9 enzyme activity, functional characterization of the wild-type- and variant-encoded UGT1A9 isoforms was performed in vitro. Cell homogenates were prepared from UGT1A9-transfected HK293 cells and glucuronidation assays were performed against various carcinogens/carcinogen metabolites. A significant (p<0.001) 3- to 4-fold decrease in enzyme activity, determined by HPLC analysis, was observed for the UGT1A9183Gly variant as compared to its wild-type counterpart for all substrates analyzed. These results demonstrate that the UGT1A9 (Cys183Gly) polymorphism significantly alters UGT1A9 function and could potentially play an important role as risk modifier for digestive tract cancers.

Múltiplas lesões orais que progridem em um curso irreversível lento mediante expansão de áreas afetadas, no sentido de um pior prognóstico, caracterizam a leucoplasia verrucosa proliferativa. A referida lesão apresenta perfil agressivo circunstanciando indeterminado número de recidivas e alto potencial de transformação neoplásica. A tal fato, se atribui a frequente incidência em carcinoma verrucoso bem como em carcinoma espinocelular de boca invasivo e potencialmente metastático, inserindo-se este em índices de maior prevalência quando comparado ao carcinoma verrucoso em pacientes com leucoplasia verrucosa proliferativa. Vincula-se ao contexto supracitado, o envolvimento de vias de sinalização celular ocasionando o desarranjo de um complexo sistema o qual abarca atividade de oncogenes, inibição de genes supressores de tumor e alteração de reguladores do sistema de reparo do DNA, encerrando-se, por sua vez, em diversos fatores favoráveis à carcinogênese, dentro os quais a regulação negativa de cascatas pró-apoptóticas e estímulo à proliferação celular desordenada. A este processo se pode relacionar o desconcerto da via PI3K/Akt/mTOR e de um membro do complexo de pré-replicação, o MCM3. Para tanto, a análise pormenorizada do perfil evolutivo da lesão por meio do rol de diagnósticos pregressos, bem como por meio do cruzamento de dados epidemiológicos, além da caracterização de neoplasias malignas provenientes da leucoplasia verrucosa proliferativa por meio da expressão dos biomarcadores pAkt, pmTOR e MCM3, vêm a explanar aspectos ainda pouco estudados desta intrigante entidade clinicopatológica. Neste sentido, o presente trabalho analisou o histórico diagnóstico de 28 pacientes com leucoplasia verrucosa proliferativa submetendo à análise imuno-histoquímica para as supracitadas proteínas, o montante de 34 amostras dos mesmos pacientes, integrando estas, 28 de leucoplasia verrucosa proliferativa, 4 de carcinoma verrucoso e 2 de carcinoma espinocelular. Dos resultados obtidos, foi possível depreender a prevalência de lesões em mucosa jugal, rebordo alveolar e língua confirmando ainda seu perfil evolutivo em face às múltiplas lesões com alto potencial recidivante e latente insurgir do carcinoma espinocelular, este podendo ainda ser embasado por expressiva marcação de pmTOR, pAkt e MCM3. / Multiple oral lesions that progress in a slow irreversible course by expansion of affected areas, in the sense of a worse prognosis, characterize proliferative verrucous leukoplakia. The said lesion presents an aggressive profile, with an indeterminate number of recurrences and a high potential for neoplastic transformation. To this fact, it is attributed to frequent incidence in verrucous carcinoma as well as invasive and potentially metastatic invasive mouth squamous cell carcinoma, inserting itself in indices of higher prevalence when compared to verrucous carcinoma in patients with proliferative verrucous leukoplakia. It is linked to the aforementioned context, the involvement of cell signaling pathways, causing the disruption of a complex system which encompasses oncogenes activity, inhibition of tumor suppressor genes and alteration of DNA repair system regulators, ending in several factors favorable to carcinogenesis, in which negative regulation of pro-apoptotic cascades and stimulation to disordered cell proliferation. To this process one may relate the dissatisfaction of the PI3K / Akt / mTOR pathway and a member of the pre-replication complex, MCM3. Thus, the detailed analysis of the evolutionary lesion profile through the role of previous diagnoses and the cross-referencing of epidemiological data, as well as the characterization of malignant neoplasms from proliferative verrucous leukoplakia by the expression of the biomarkers pAkt, pmTOR and MCM3, come to clarify aspects that have not yet been studied in this intriguing clinicopathological entity. Thus, the present study analyzed the historical diagnosis of 28 patients with proliferative verrucous leukoplakia submitting to immunohistochemical analysis for the aforementioned proteins, the amount of 34 samples from the same patients, comprising 28 of proliferative verrucous leukoplakia, 4 of verrucous carcinoma and 2 of squamous cell carcinoma. From the results obtained, it was possible to detect the prevalence of lesions in the buccal mucosa, alveolar ridge and tongue, and the confirmation of its evolutionary profile in the face of the multiple lesions with high recurrent and latent insurgent potential of squamous cell carcinoma, which may be supported by a significant mark of pmTOR, pAkt and MCM3.

<p>Mutation of the p53 gene appears to be an early event in skin cancer development. The present study is based on morphology and represents a cellular and genetic investigation of p53 alterations in normal human skin and basal cell cancer.</p><p>Using double immunofluorescent labelling, we have demonstrated an increase in thymine dimers and p53 protein expression in the same keratinocytes following ultraviolet radiation. Large inter-individual differences in the kinetics of thymine dimer repair and subsequent epidermal p53 response were evident in both sunscreen-protected and non-protected skin. The formation of thymine dimers and the epidermal p53 response were partially blocked by topical sunscreen. We have optimized a method to analyze the p53 gene in single cells from frozen tissue sections. In chronically sun-exposed skin there exist clusters of p53 immunoreactive keratinocytes (p53 clones) in addition to scattered p53 immunoreactive cells. Laser assisted microdissection was used to retrieve single keratinocytes from immunostained tissue sections, single cells were amplified and the p53 gene was sequenced. We have shown that p53 mutations are prevalent in normal skin. Furthermore, we detected an epidermal p53 clone which had prevailed despite two months of total protection from ultraviolet light. Loss of heterozygosity in the PTCH and p53 loci as well as in the sequenced p53 gene was determined in basal cell cancer from sporadic cases and in patients with Gorlin syndrome. Allelic loss in the PTCH region was prominent in both sporadic and hereditary tumors, while loss of heterozygosity in the p53 locus was rare in both groups. p53 mutations found in the hereditary tumors differed from the typical mutations found in sporadic cases. In addition, we found genetically linked subclones with partially different p53 and/or PTCH genotypes in individual tumors. Our data show that both genes are important in the development of basal cell cancer.</p>

Lymphomas and leukemias are the most common cancer in children and young adults and in utero exposure to carcinogens may contribute to the etiology of these cancers. A polycyclic aromatic hydrocarbon (PAH), dibenzo[a,l]pyrene (DBP), was administered to pregnant mice (15 mg/Kg b.w., gavage) on gestation day 17. Significant mortalities in young offspring were observed due to T-cell lymphoma. Lung and liver tumors also were observed in survivors at 10 months of age. To assess the role of the Aryl Hydrocarbon Receptor (AHR), we utilized crosses of B6129SF1/J (responsive) mice with strain 129S1/SvImJ (non-responsive). Offspring born to AHR non-responsive mothers had greater susceptibility to lymphoma, irrespective of offspring genotype. Responsive offspring displayed increased mortality if the mother was responsive. Lung adenomas showed Ki-ras mutations and exhibited a 50% decrease and a 35-fold increase in expression of Rb and p19/ARF mRNA, respectively. To examine the risk/benefit of maternal dietary phytochemical treatment against transplacental cancer, 2000 ppm indole-3-carbinol (I3C) was given to pregnant mice through diet from gestation day 9 till weaning. I3C significantly lowered mortality caused by lymphomas regardless of the maternal genotype, and also reduced lung tumor multiplicity in offspring born to AHR [superscript b-l/d] dams. Distribution of I3C in most maternal and fetal tissues was quantified following a single gavage of [¹⁴C]-I3C to the pregnant mice. DBP-DNA adducts were observed in both maternal and fetal tissues by ³³P postlabeling and HPLC analysis and were modulated by I3C and AHR genotype. I3C also modulated phase I and phase II enzyme protein expression in dams and gene expression in newborn thymus. I3C chemoprotection may involve modification of the bioavailability of DBP to the fetus and/or modulation of gene expression in the fetus as well. This is the first demonstration that transplacental exposure to an environmental PAH can induce a highly aggressive lymphoma in mice. These results raise the possibility that PAH exposures to pregnant women could contribute to similar cancers in children and young adults and, that the addition of chemoprotective agents to the maternal diet may reduce cancer risk among offspring. / Graduation date: 2006

Graduation date: 2006