Small molecule disruption of RAD52 rings as a mechanism for precision medicine in BRCA deficient cancers Suppression of RAD52 causes synthetic lethality in BRCA deficient cells. Yet pharmacological inhibition of RAD52, which binds single-strand DNA (ssDNA) and lacks enzymatic activity, has not been demonstrated. Here, we identify the small molecule 6-hydroxy-DL-dopa (6-OH-dopa) as a major allosteric inhibitor of the RAD52 ssDNA binding domain. For example, we find that multiple small molecules bind to and completely transform RAD52 undecamer rings into dimers, which abolishes the ssDNA binding channel observed in crystal structures. 6-OH-dopa also disrupts RAD52 heptamer and undecamer ring superstructures, and suppresses RAD52 recruitment and recombination activity in cells with negligible effects on other double-strand break repair pathways. Importantly, we show that 6-OH-dopa selectively inhibits the proliferation of BRCA deficient cancer cells, including those obtained from leukemia patients. Taken together, these data demonstrate small molecule disruption of RAD52 rings as a promising mechanism for precision medicine in BRCA deficient cancers. How RNA transcripts coordinate DNA recombination and repair Genetic studies in yeast indicate that RNA transcripts facilitate homology-directed DNA repair in a manner that is dependent on RAD52. The molecular basis for so-called RNA-DNA repair, however, remains unknown. Using reconstitution assays, we demonstrate that RAD52 directly cooperates with RNA as a sequence-directed ribonucleoprotein complex to promote two related modes of RNA-DNA repair. In a RNA-bridging mechanism, RAD52 assembles recombinant RNA-DNA hybrids that coordinate synapsis and ligation of homologous DNA breaks. In a RNA-templated mechanism, RAD52 mediated RNA-DNA hybrids enable reverse transcription dependent RNA-to-DNA sequence transfer at DNA breaks that licenses subsequent DNA recombination. Notably, we show that both mechanisms of RNA-DNA repair are promoted by transcription of a homologous DNA template in trans. In summary, these data elucidate how RNA transcripts cooperate with RAD52 to coordinate homology-directed DNA recombination and repair in the absence of a DNA donor, and demonstrate a direct role for transcription in RNA-DNA repair. Characterization of DNA polymerase θ as a reverse transcriptase RNA-to-DNA sequence has been observed in human cells, but how the phenomena occurs remains unknown. Multiple lines of evidence suggest putative reverse transcriptase (RT) activity as a potential mechanism for how RNA sequence can alter chromosomal DNA, but the source of this RT remains unknown. Here, we have identified that the unique A-family DNA polymerase theta (Polθ) displays robust RT activity, a characteristic not found in any other human polymerase tested from the A, B, X, and Y families. We propose that Polθ may be responsible for the observed RT activity in human cells. / Biomedical Sciences

En réponse à des signaux environnementaux, la cellule module son programme transcriptionnel afin de mener à une expression spatio-­temporelle adéquate des gènes. L’orchestration d’une telle adaptation repose entre autres sur la séquence primaire du génome, son organisation au sein de la chromatine, ainsi que sa structure tridimensionnelle au sein du noyau. De plus, de nombreux régulateurs permettent d’intégrer ces différents niveaux de régulation afin de contrôler l’activité de l’ARN polymérase II. Dans ce contexte, le complexe cohésine et son facteur de charge sur l’ADN, NIPBL, jouent un rôle clé dans l’interconnexion fonctionnelle entre l’organisation 3D du génome et la transcription. En effet, ces facteurs modulent l’activation de la transcription en rapprochant des régions enhancers de promoteurs et participent à la formation de domaines d’interactions chromosomiques. Par ailleurs, des mutations de NIPBL et du complexe cohésine sont associées au Syndrome de Cornelia de Lange (CdLS), une pathologie caractérisée par une altération de l’expression des gènes. Toutefois, les mécanismes moléculaires impliqués dans la régulation de la transcription par NIPBL et cohésine sont encore méconnus. L’objectif général de mon projet de doctorat est de définir le rôle de NIPBL et du complexe cohésine dans la régulation du lien entre la topologie du génome et le contrôle de l’expression des gènes. Dans un premier temps, nous montrons que les gènes dérégulés dans le CdLS sont préférentiellement organisés au sein de communautés de gènes, des structures formées par des interactions d’éléments régulateurs non codants ainsi que de gènes dans l’espace chromosomique tridimensionnel. Au sein de cette organisation, les gènes affectés par des mutations de NIPBL ou de la sous-­unité SMC1A du complexe cohésine sont retrouvés positionnés à portée de régions occupées par cohésine et NIPBL et interagissent par l’intermédiaire de contacts promoteur-­promoteur. Dans un second temps, nous présentons des données suggérant un rôle de cohésine dans la régulation de l’initiation de la transcription et un rôle de NIPBL dans le contrôle de la relâche de la pause. Enfin, nous apportons des évidences d’une fonction de NIPBL et cohésine dans la régulation du niveau basal et de l’activation des gènes dont l’expression est stimulée par des hormones. Dans leur ensemble, ces travaux contribuent à l’amélioration des connaissances sur la contribution de l’architecture des chromosomes aux mécanismes généraux de la régulation de la transcription. / In response to environmental signals, the cell modulates its transcriptional program in order to carry out appropriate spatiotemporal gene expression. The orchestration of this adaptation relies on the primary sequence of the genome, its organization into chromatin, and its tridimensional structure inside the nucleus. Moreover, multiple regulators integrate these different regulation levels in order to control the activity of RNA polymerase II. In this context, the cohesin complex and its DNA loader, NIPBL, play a pivotal role in the functional interconnection between the 3D organization of the genome and transcription. Indeed, these factors modulate the activation of transcription by bringing enhancers and promoters into close proximity and participate in the formation of chromosome interaction domains. Moreover, mutations in NIPBL and the cohesin complex are associated with the Cornelia de Lange Syndrome (CdLS), a pathology characterized by gene expression changes. However, the exact molecular mechanisms involved in the regulation of transcription by NIPBL and cohesin are still not understood. The general aim of my doctoral research is to define the role of the cohesin complex and NIPBL in the regulation of the connection between genome topology and gene expression control. First, we show that genes deregulated in CdLS are preferentially organized into connected gene communities, structures emerging from the interactions of noncoding regulatory elements and genes in the three-­dimensional chromosomal space. Within this organization, genes affected by mutations in NIPBL and the SMC1A subunit of the cohesin complex are positioned within reach of NIPBL-­ and cohesin-­occupied regions through promoter-­ promoter interactions. In addition, we present data suggesting a role of the cohesin complex in the initiation of transcription and a role of NIPBL in the control of pause release. Finally, we show evidence of a function of NIPBL and cohesin in the regulation of the basal level and the activation of genes stimulated by hormones. Ultimately, this work aims to gain insight into the contribution of the architecture of chromosomes to the general mechanisms of transcriptional regulation.

Pacientes com câncer de mama apresentam menores níveis de 1,25(OH)2D3 ou 25(OH)D3 em relação às mulheres sem a doença. Embora linhagens de câncer de mama apresentem inibição do crescimento em concentrações supra-fisiológicas de 1,25(OH)2D3, forma ativa da vitamina D, ainda não se demonstrou se o hormônio exerce efeito antiproliferativo, em concentrações fisiológicas, em tumores de seres humanos. A suplementação de calcitriol pode ser indica a mulheres pós-menopausadas para prevenir a perda óssea. Nosso objetivo foi avaliar em pacientes com câncer de mama, pós menopausadas, a dimensão do tumor, taxa de proliferação (expressão de Ki67), concentração sérica de 1,25(OH)2D3 e 25(OH)D3, expressão gênica tumoral do receptor de vitamina D (VDR) e alguns genes alvos como, CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2, antes a após um mês de suplementação oral de calcitriol. Foram estudadas 24 pacientes com doença operável, idade mediana de 57 anos. As primeiras 10 pacientes e as 14 seguintes receberam 0,25 e 0,50g/dia de calcitriol, respectivamente, por um período mediano de 31 dias. Três quartos das pacientes apresentavam nível sérico de insuficiência de 25(OH)D3 ou insuficiência relativa (<30ng/ml) e após a suplementação, nenhuma paciente apresentou elevação dos níveis séricos de 1,25(OH)2D3 e 25(OH)D3. Embora a dimensão tumoral, mensurada por ultrasonografia, não apresentasse variação, a imuno-expressão de Ki67 sofreu um redução relativa mediana de 40%. A expressão relativa de VDR, CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2 não se alterou com a suplementação. Nossos dados indicam que tumores de mama expressam VDR, e que após suplementação oral de calcitriol, ocorre uma redução da proliferação. Este efeito merece ser elucidado, desde que genes alvo clássicos da 1,25(OH)2D3 não parecem ser mediadores do efeito anti-proliferativo, em amostras de câncer de mama de pacientes pós menopausadas. / Breast cancer patients present lower 1,25(OH)2D3 or 25(OH)D3 serum levels than unaffected women. Although breast cancer cell lines are growth inhibited by vitamin D supra-physiological concentrations, there is much uncertainty about the anti-proliferative effect of physiological concentrations of 1,25(OH)2D3, the active form of vitamin D, in breast cancer specimens in vivo. Vitamin D supplementation to post-menopausal women may be indicated to reduce bone loss. Our aim was to evaluate tumor dimension, proliferation rate (Ki67 expression), 25(OH)D3 and 1,25(OH)2D3 serum concentration, and tumor expression of vitamin D receptor (VDR), and of some target genes as CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2, before and after a one month calcitriol supplementation to post-menopausal breast cancer patients. Twenty four patients with operable disease, median age 57 years, were enrolled. The first tem patients were supplemented with calcitriol 0.25g/d and the next 14 patients, with 0.50g/d, for a median period of 31 days. Three fourths of the patients presented 25(OH)D3 insufficiency or relative insufficiency (<30 ng/mL) and after calcitriol supplementation, none of them presented an elevation of 1,25(OH)2D3 or 25(OH)D3 serum concentration. Although tumor dimension, evaluated by ultrasonography, did not vary, a median relative reduction of 40% in Ki67 immuno-expression, was observed. No differences in VDR, CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2 mRNA relative expression were detected between pre and post-supplementation samples. No differences in VDR, CYP27B1 and CYP24A1 tumor relative expression were detected following supplementation. Our data indicate that VDR expression is detected in breast cancer samples and that growth inhibition takes place after calcitriol oral supplementation. This anti-proliferative effect deserves further investigation, as classical target genes do not seem to be involved.

A epilepsia é um transtorno do funcionamento cerebral caracterizado por crises epilépticas recorrentes que acomete cerca de 1 a 2% da população mundial. A epilepsia do lobo temporal (ELT) é o subtipo mais prevalente. A refratariedade aos medicamentos é comum e cerca de 40 % destes pacientes apresentam transtornos psiquiátricos. Neste trabalho utilizamos o método de TacMan real time PCR para quantificar o mRNA de subtipos dos receptores de noradrenalina, dopamina, serotonina e substância P em hipocampos cirurgicamente removidos de pacientes com ELT para conhecer o papel destes na ELT com ou sem comorbidade psiquiátrica (depressão ou psicose). Nossa amostra foi de 48 pacientes com ELT sem (Epilepsia - 24) ou com comorbidade psicótica (Psicose - 10) ou depressiva (Depressão - 14) e 8 Controles (necrópsias). O receptor adrenérgico-&#945;2A (AD2A) apresentou diferença entre os grupos (p = 0,0059) com significância para a variável Antiepiléptico (p = 0,0374) e pós-teste significante de maior expressão do mRNA de AD2A no grupo Epilepsia comparado com Controle e com Psicose. A ativação dos receptores &#945;2A no hipocampo pelos antiepilépticos pode explicar nossos achados do grupo Epilepsia comparado ao Controle, corroborando a literatura acerca do AD2A na epilepsia e em relação aos antiepilépticos. O AD2C mostrou diferença entre os grupos (p = 0,0016), sem significância nas variáveis de controle e significante maior expressão do mRNA de AD2C no grupo Epilepsia comparado ao Controle e Psicose. O AD2C é encontrado em áreas que processam informações sensoriais e controlam atividades motoras e emocionais relacionadas, o que pode explicar nossos resultados. Parece ser importante na patologia relacionada à ELT e merece ser estudado. A não diferença entre Epilepsia e Depressão para AD2A e AD2C, parecem confirmar uma relação bi-direcional ou um mecanismo patogênico comum entre epilepsia e depressão, enquanto a menor expressão de AD2A e AD2C nos psicóticos parece indicar diferenças nos mecanismos adrenérgicos ligados a psicose e epilepsia. D2 mostrou diferença entre os grupos (p = 0,0125) com resultado significativo para a variável Subtipo de Diagnóstico Psiquiátrico (p = 0,0239), provavelmente devido a cronicidade da doença e a quantidade de episódios depressivos apresentados pelos sujeitos. Quanto maior a freqüência das crises (p = 0,0381) maior a expressão do D2 no grupo Epilepsia e no Depressão comparados ao Controle. Estes achados sugerem a participação deste receptor na depressão comórbida na ELT; corroboram que o monitoramento dopaminérgico límbico pode ser útil para desenvolver novos antidepressivos e propõem pesquisas futuras sobre D2 em epilépticos. A participação de 5-HT2A na ELT é indicada, pois, sua maior expressão no grupo Epilepsia em relação ao Controle foi significativa (p = 0,0273). Quanto maior a freqüência das crises epilépticas maior a expressão do 5-HT2A (p = 0, 0433). Não encontramos resultados significativos referentes aos receptores D4, 5-HT1A, 5-HT2C e NK1. Nossos resultados mostraram a possibilidade da aplicação do TacMan real time PCR no estudo de receptores de neurotransmissores, sugeriu a importância dos receptores estudados na ELT e comorbidades psiquiátricas, e que outras estruturas límbicas, como a amígdala, sejam focos de investigação. / Epilepsy is a mental functional disorder characterized by recurrent seizures that affect about 1 to 2% of world population. Temporal lobe epilepsy (TLE) is the most prevalent subtype. The refractory to medication is common and about 40% of these patients have psychiatric disorders. This study used the TacMan real time PCR method to quantify noradrenergic, dopaminergic, serotoninergic and substance P receptors subtypes mRNA expression in hippocampus surgically removed from patients with TLE to know their role in TLE with or without psychiatric commorbity (depression or psychosis). Our sample consisted of 48 TLE patients without (Epilepsy - 24) or with psychotic (Psychosis - 10) or depressive (Depression - 14) commorbity and 8 Controls (necropsies). The &#945;2A adrenergic receptor (AD2A) showed difference between groups (p = 0.0059) with significance for Antiepileptic Medication variable (p = 0.0374) and post-hoc test significantly greater AD2A mRNA expression of Epilepsy group compared with Control and Psychosis. The activation of hippocampus &#945;2A receptors by antiepileptic drugs can explain our findings of the Epilepsy group compared with Control, corroborating the literature about the AD2A in epilepsy and for antiepileptic drugs. The AD2C showed differences between groups (p = 0.0016) without significance in the variables of control and significantly greater AD2C mRNA expression of the Epilepsy group compared to Control and Psychosis. The AD2C is found in areas that process sensory information and control motor and emotional related activities, which may explain our results. It seems to be important in the pathology related to TLE and deserves to be studied. No differences between Epilepsy and Depression to AD2A and AD2C seem to confirm a bi-directional relation or a common pathogenic mechanism between epilepsy and depression, while the lowest AD2A and AD2C expression within psychotics seem suggests differences in adrenergic mechanisms linked to psychosis and epilepsy. D2 showed differences between groups (p = 0.0125) with significant results for the variable Subtype of Psychiatric Diagnosis (p = 0.0239), probably due to chronic disease and the number of depressive episodes presented by subjects. The higher the frequency of seizures (p = 0.0381) the higher was the D2 expression within Epilepsy group compared with Control and Depression compared to Control. These findings suggest the involvement of this receptor in TLE commorbid depression; corroborate that limbic dopaminergic monitoring may be useful in developing new antidepressants and propose future research on D2 in epileptics. The participation of 5-HT2A in TLE is indicated, therefore its significant higher expression in the Epilepsy group in relation to Control (p = 0.0273). The higher the frequency of seizures the higher was the 5-HT2A expression (p = 0.0433). We found no significant results for the D4, 5-HT1A, 5-HT2C and NK1 receptors. Our results showed the possibility of TacMan real time PCR method application in TLE neurotransmission receptors study, suggested the importance of the studied receptors in TLE and psychiatric commorbities and that other limbic structures, as the amygdala, should be investigation targets.

O carcinoma diferenciado de tireóide (CDT) abrange 95% de todas as doenças malignas da tireóide. Nos EUA, aumentou em 2,4 vezes nos últimos anos (1973-2002). O seu tratamento inclui tireoidectomia total, seguido por terapia com radioiodo e supressão do TSH com L-tiroxina. A doença pode recidivar em ~20% dos casos, sendo necessária avaliação periódica através de exames de imagens e dosagem de tireoglobulina sérica (TGs). Os Anticorpos (Acs) anti-TG podem ser detectados em 15 a 25% dos pacientes, comprometendo, parcialmente, o uso da TGs como marcador de recidiva do câncer. Um método alternativo proposto para monitorar os pacientes é a detecção de células tireoidianas em sangue periférico, através da mensuração do RNA mensageiro de TG (RNAm-TG) pela técnica de RTPCR em tempo real. Esta nova metodologia aumenta a sensibilidade da detecção desta molécula. O objetivo deste estudo é verificar a significância da quantificação do RNAm-TG, como método diagnóstico complementar no acompanhamento a longo prazo de pacientes com CDT. Amostras de sangue de 45 pacientes (25 sem metástase, 14 com metástase ganglionar e 6 com metástase à distância) foram coletadas nos tempos: antes e 24, 48, 72 horas, 7 dias, 1, 3, 6, 9 meses, 1, 2, 4, 5, 6 e 7 anos após a dose ablativa de radioiodo. Foi realizada extensiva padronização da técnica com a finalidade de excluir interferências metodológicas, empregando dois genes controles interno (GAPDH e HPRT1) para o cálculo da concentração do RNAm-TG. Concomitantemente foi realizada a mensuração de TGs, perfil hormonal e de anticorpos anti-TG. A pesquisa de corpo inteiro, realizada 7 dias após a dose terapêutica, estabeleceu o estadio clínico inicial dos pacientes. Não foi possível estabelecer um valor de corte para o RNAm-TG. O RNAm-TG não diferenciou os estadios clínicos da doença ao longo do tempo, independente do gene controle interno utilizado, e tampouco quando analisaram-se os dados na presença de Acs anti-TG e TSH30ng/mL. A TGs diferenciou os estadios clínicos ao longo do tempo. Concluiu-se que, o RNAm-TG não é um bom marcador de recidiva do CDT, mesmo quando considerou-se critérios de padronização da técnica, avaliação em longo prazo e presença de Acs anti-TG, sendo assim não poderia ser utilizado como método diagnóstico complementar no acompanhamento de pacientes com CDT. Este estudo demonstra que a técnica de RT-PCR em tempo real é muito sensível perdendo especificidade, inviabilizando sua utilização no acompanhamento dos pacientes com CDT / The differentiated thyroid carcinoma (DTC) encloses 95% of all thyroid malignant disease. In USA, it increased 2,4 times in recent years (1973- 2002). The treatment includes total thyroidectomy, ablation with radioiodine (RAI) followed by TSH suppression with L-Thyroxine. The cancer recurrence occurs in 20% of the cases. Periodic evaluation through imaging examinations and serum thyroglobulin (TG) measurements by imunoassays method is recommended for careful follow-up of these patients. The anti-TG antibodies prevalence is 15-25% and would impair, partially, the serum TG use as a tumor marker. An alternative method to identify the recurrence of the tumor is the thyroid cells detection in peripheral blood, through the TG messenger RNA quantification (mRNA-TG) by real time RT-PCR. This new methodology increases the sensitivity detection for this molecule. The objective of this study was to verify the mRNA-TG peripheral blood quantification significance, as a complementary diagnostic method in the long term follow up of patients with DTC. Fourty five blood samples from patients with DTC have been collected before and 24, 48, 72 hours, 7 days, 1, 3, 6, 9 months, 1, 2, 4, 5, 6 and 7 years after the ablation therapy. Extensive technique standardization for mRNA-TG measurements was carried out to exclude methodological interventions and two housekeeping genes (GAPDH and HPRT1) were used to calculate the mRNA-TG concentrations. Concomitantly, serum TG measurements, hormonal profile and antibodies anti-TG assays were performed. The whole body scan was performed 7 days after RAI ablation to determine the stage of the disease. It was not possible to establish a cut-point value for mRNA-TG. The mRNA-TG did not differentiated the clinical stage of the disease in the long term follow-up and neither in the presence of anti-TG antibodies and TSH30ng/mL. Serum TG was able to differentiate the clinical stage of the patients during the follow-up. In conclusion mRNA-TG is not a good marker for the DCT recurrence, even when technical standardization, long term evaluation and the presence of antibodies anti-TG were considered. Thus it could not be used as a complementary diagnostic method in the DTC patients follow-up. This study confirmed the high sensivity of the real time RT-PCR whereas with very low specificity, consequently is unviable to be used in the DTC patients follow-up

Estudos sugerem que a presença de células metastáticas ocultas em medula óssea pode ser fator prognóstico em câncer de mama. Além disso, é possível que um perfil gênico tumoral específico, caracterizado por repressão da expressão gênica, esteja associado à detecção de células tumorais na medula óssea. O silenciamento de genes é controlado pela desacetilação de histonas e metilação de DNA, esta última catalisada por enzimas DNA metil transferases. Outro alvo de metil-transferases são as histonas, e histona H3 quando sofre metilação em lisina 9, gera sítio de ligação a proteínas HP1 (Heterocromatin protein-1 ou cromobox). Membros da família HP1 (HP1Hsalfa, HP1Hsbeta e HP1HsY) participam da formação da heterocromatina e da regulação da expressão de genes. Logo, nosso objetivo foi determinar no tumor primário de mama, a expressão de HP1Hsalfa, HP1Hsbeta e HP1Hsy , que participam da repressão gênica, em relação à presença ou ausência de células metastáticas ocultas na medula óssea. Neste estudo foram incluídas 37 pacientes de forma prospectiva, atendidas no Instituto Brasileiro de Controle do Câncer (IBCC) no período de junho de 2004 a julho de 2005, com diagnóstico histopatológico de carcinoma invasivo de mama, estádio clínico (EC) I (16,2%), II (51,4%) ou III (32,4%), segundo a classificação patológica. A idade mediana das pacientes foi 63 anos (41 a 90) e 62.2% delas encontravam-se na pós-menopausa, sendo que 24.3% relatava história familiar para câncer de mama. O tipo histológico predominante foi carcinoma ductal invasivo (89.2% dos casos), sendo, o restante, representado por carcinoma lobular invasivo (10.8%). Foram coletadas amostras de tumor primário de mama e de aspirado de medula óssea de cada paciente. A presença de células metastáticas ocultas (CMO) na medula óssea (MO) foi detectada através da expressão de citoqueratina 19 (CK19) pelo método de nested RT-PCR. A expressão relativa dos genes HP1Hsalfa, HP1Hsbeta e HP1Hsy foi determinada no tumor primário, usando-se a técnica de RT-PCR em tempo real. Presença de CMO foi detectada na MO de 20 pacientes (54.1%). Não observamos diferença na expressão de HP1Hs? (1,93 ± 2,25 MO- vs 3,84 ± 5,53 MO+), HP1Hs? (6,74 ± 6,31 MO- vs 6,49 ± 5,86 MO+) e HP1Hs? (24,58 ± 11,14 MO- vs 24,91 ± 15,88 MO+) entre as amostras tumorais de pacientes com presença (MO+) ou ausência (MO-) de micrometástase medular. Também não observamos variação da expressão de genes HP1 em relação ao comprometimento linfonodal, dimensão e grau histológico do tumor, expressão tumoral de receptores de estrógeno e estado menopausal da paciente. A expressão de HP1Hsalfa em tumores de pacientes com câncer de mama ERBB2 negativos, entretanto, foi maior do que em tumores ERBB2 positivos. Nossos dados indicam que em tumores de mama, a expressão de HP1Hsalfa, HP1Hsbeta e HP1Hsy não parece se associar à presença de células ocultas em medula óssea / Studies suggest that the presence of occult metastatic cells (OMC) in the bone marrow (BM) may be a prognostic factor in breast cancer. Besides, it is possible that a specific tumor gene profile, characterized by repression of gene expression, may be associated to the presence of tumoral cells in the bone marrow. Gene silencing is controlled by histone deacetylation and DNA methylation, the last one catalized by enzymes DNA methyltransferases (DNMTs). Histones are another target of methyltransferases, and methylation of histone H3 on lysine-9 generate a binding site for HP1 proteins (Heterocromatin protein-1 or chromobox). Members of the HP1 family (HP1Hsalfa, HP1Hsbeta e HP1Hsy) take part in heterochromatin formation and gene expression regulation. Hence, our aim was to determine in the primary tumor of the breast, the expression of HP1Hsalfa, HP1Hsbeta e HP1Hsy, which participate in gene repression, in the presence or absence of occult metastatic cells in the bone marrow. In this study, 37 patients treated at Instituto Brasileiro de Controle do Câncer, from June 2004 to July 2005, with invasive breast cancer histopathologically confirmed, pathological clinical stages I (16,2%), II (51,4%) or III (32,4), were included. The median age of the patients was 63 years (41 to 90), 62.2% were post-menopausal and 24.3% reported family history of breast cancer. Invasive ductal carcinoma was diagnosed in most patients (89.2%), and invasive lobular carcinoma was detected in the other patients (10.8%). Tumor samples and bone marrow aspirates were obtained from each patient. The presence of CMO in BM was detected by keratin-19 (CK19) expression by nested RT-PCR. The relative expression of the genes HP1Hsalfa, HP1Hsbeta e HP1Hsy was determined by real-time RT-PCR. Occult metastatic cells (OMC) in BM were detected in 20 patients (54.1%). No differences were observed in the expression of HP1Hs? (1,93 ± 2,25 BM- vs 3,84 ± 5,53 BM+), HP1Hsalfa (6,74 ± 6,31 BM- vs 6,49 ± 5,86 BM+) and HP1Hsbeta (24,58 ± 11,14 BM- vs 24,91 ± 15,88 BM+) between tumor samples of BM+ patients and BM- patients. Variations of HP1 gene expression were neither observed according to lymph node involvement, tumor size, histological grade, estrogen receptor status and menopausal status. However, HP1Hsbeta expression in ERBB2-negative tumors was higher than in ERBB2-positive tumors. Our data indicate that in breast cancer tumors, expression of HP1Hsalfa, HP1Hsbeta e HP1Hsy does not seem to be associated with the presence of occult metastatic cells in the bone marrow

Pacientes com câncer de mama localmente avançado são submetidas à quimioterapia neoadjuvante na tentativa de reduzir a dimensão do tumor e aumentar a possibilidade da realização de uma cirurgia conservadora. Nosso grupo identificou previamente através da tecnologia de cDNA microarray, trios de genes, incluindo BZRP, CLPTM1, MTSS1, NOTCH1, NUP210, PRSS11, RPL37A, SMYD2 e XLHSRF-1, cuja expressão era capaz de predizer a resposta à quimioterapia neoadjuvante com doxorrubicina e ciclofosfamida em pacientes com câncer de mama. No presente estudo, avaliamos se a expressão destes genes é reprodutível na identificação de pacientes responsivas e não-responsivas através de RT-PCR em tempo real, que representa uma técnica mais acessível. Avaliamos inicialmente amostras de 28 pacientes anteriormente estudadas (grupo de validação técnica = 23 responsivas e cinco não-responsivas) e a seguir um grupo de 14 novas pacientes (grupo de validação biológica = 11 responsivas e três não-responsivas). Dentre os trios de genes inicialmente identificados, a expressão de RPL37A + XLHSRF-1 + NOTCH1 e RPL37A + XLHSRF-1 + NUP210 classificou corretamente 86% (24/28) das amostras do grupo de validação técnica e 71% (10/14) das amostras do grupo de validação biológica, através de análise de classificação discriminante. Desse modo, esses trios não demonstraram a mesma precisão em comparação com resultados de cDNA microarray. Uma nova análise combinatória foi realizada na procura do melhor modelo preditivo utilizando valores de expressão obtidos por RT-PCR em tempo real. Identificamos então um novo trio, composto pelos genes RPL37A, SMYD2 e MTSS1, cuja expressão classificou corretamente 93% das amostras do grupo de validação técnica (22/23 responsivas e 4/5 não-responsivas) e 79% do grupo de validação biológica (8/11 responsivas e 3/3 não-responsivas). Portanto, o teste apresentou 88% de sensibilidade e especificidade em detectar pacientes responsivas para o total de amostras analisadas. Ao verificarmos o poder de classificação do mesmo grupo de genes, utilizando os valores de expressão pela análise de cDNA microarray, observamos um resultado semelhante (91% de sensibilidade e especificidade em reconhecer as amostras responsivas). Dessa forma, demonstramos que o perfil de expressão gênica obtido com cDNA microarray é reprodutível através do uso de RT-PCR em tempo real. Um estudo integrando um maior número de pacientes e uma plataforma de cDNA microarray mais abrangente pode auxiliar na identificação de um modelo preditivo baseado em grupos de genes mais acurado para antever a resposta ao tratamento com quimioterapia baseada em doxorrubicina. / Patients with locally advanced breast cancer are submitted to primary chemotherapy as an attempt to reduce tumor dimension and increase breast conserving surgery rates. Our group has previously identified through cDNA microarray technology gene trios, including BZRP, CLPTM1, MTSS1, NOTCH1, NUP210, PRSS11, RPL37A, SMYD2 and XLHSRF-1, whose expression was capable of predicting response to neoadjuvant chemotherapy with doxorubicin and cyclophosphamide in breast cancer patients. In the current study, it was evaluated whether expression of these genes is reproducible in the identification of responsive and non-responsive patients by real time RT-PCR, which represents a more accessible technique. We initially evaluated samples from 28 patients earlier studied (technical validation group = 23 responsive and 5 non-responsive) and subsequent to a new 14 patients set (biological validation group = 11 responsive and three non-responsive). Among the initially identified gene trios, RPL37A + XLHSRF-1 + NOTCH1 and RPL37A + XLHSRF-1 + NUP210 expression correctly classify 86% (24/28) samples from the technical validation group and 71% (10/14) samples from the biological validation group, through discriminant classification analysis. Therefore, these trios didnt demonstrate the same precision as compared with cDNA microarray results. A new combinatorial analysis was also performed in search of the best predictive model using real time RT-PCR expression values. A new trio was identified, represented by RPL37A, SMYD2 and MTSS1 genes, whose expression correctly classified 93% samples from technical validation group (22/23 responsive and 4/5 non-responsive) and 79% samples from biological validation group (8/11 responsive samples and 3/3 non-responsive samples). Therefore, the test presented 88% sensibility and specificity in identifying responsive patients for all samples analyzed. By means of verifying the classification strength of the same gene group, using cDNA microarray expression values, we observed a similar result (91% sensibility and specificity in recognizing responsive samples). Thus, we demonstrated that gene expression profile obtained by cDNA microarray is reproducible through real time RT-PCR. A study integrating a larger number of patients and a more comprehensive cDNA microarray platform may help the identification of a more accurate predictive model based on gene groups to foresee response to doxorubicin-based chemotherapy treatment.

Os genes homeobox são uma família de genes reguladores que são vitais para vários aspectos do crescimento e diferenciação celular. Recentemente, implicações dos genes HOXA7, HOXC6 e TGIF na gênese e progressão tumoral vêm sendo verificadas. Entretanto, o envolvimento desses genes em carcinomas epidermóides (CE) de boca ainda não foi demonstrado. A possível presença de transcritos dos genes HOXA7, HOXC6 e TGIF em carcinomas epidermóides de boca e em tecidos não tumorais adjacentes (TN) foi analisada. Os transcritos dos genes foram amplificados por RT-PCR e sua localização celular determinada por hibridização in situ (ISH) com sondas de mRNA específicas. A amplificação do HOXA7 foi observada em 70% dos casos sendo 15% apenas nas amostras TN, 45% somente nos CEs e 10% em ambos tecidos. Nenhuma amplificação do HOXC6 foi observada. O TGIF foi amplificado em 80% dos casos, sendo 5% somente nas amostras TN, 20% nos CEs e 55% em ambos tecidos. Análises estatísticas mostraram que não havia diferença significante entre a amplificação do transcrito HOXA7 ou TGIF e o tipo de tecido analisado. Além disso, nenhuma associação entre a amplificação dos transcritos nas amostras CE e os aspectos clínicos foi observada. O sinal de hibridização in situ foi similar para os transcritos HOXA7 e TGIF. Nas amostras TN o sinal da ISH foi intenso no epitélio, ora disperso sendo mais proeminente na camada espinhosa ora mais proeminente nas camadas basais e suprabasais. Nos CEs os transcritos foram localizados por toda neoplasia sendo que o sinal era menor em áreas menos diferenciadas. Esses resultados mostram que o HOXC6 não está envolvido com a carcinogênese oral enquanto que a presença dos transcritos HOXA7 e TGIF principalmente em regiões bem diferenciadas dos carcinomas epidermóides de boca sugere uma participação desses genes nesta neoplasia / Homeobox genes comprise a family of developmental regulators that are vital for several aspects of growth and differentiation. Recently HOXA7, HOXC6 and TGIF genes have been implicated with carcinogenesis and tumoral progression. However their involvement with oral squamous cell carcinomas (OSCC) has not been demonstrated yet. The possible presence of HOXA7, HOXC6 and TGIF transcripts in OSCC and adjacent non-tumoral tissues (NT) was verified. Transcripts were amplified by RT -PCR and its cellular localization was determined by in situ hybridization with specific riboprobes. Amplification of HOXA7 was seen in 70% of cases, 15% only in NT tissues, 45% only in OSCC samples and 10% in both tissues. No amplification of HOXC6 was observed. TGIF was amplified in 80% of cases, 5% only in NT tissues, 20% only in OSCC samples and 55% in both tissues. Statistical analysis showed that there was no significant difference between amplification of HOXA7 or TGIF and the type of tissue analyzed. Moreover, no association between amplification of transcripts in OSSC and clinical aspects was observed. ISH signal was similar for HOXA7 and TGIF transcripts. In NT tissues there was an intense expression in the epithelium, either in basal and suprabasal layers or disperse and more intense in the spinous layer. In OSCC transcripts were locali zed in all tumoral cells, but in poorly differentiated areas the signal was less intense. These results show that HOXC6 was not involved in oral carcinogenesis while the presence of HOXA7 and TGIF transcripts in OSSC, mostly in well differentiated regions, suggests a participation of these genes in OSCC

Genes da família homeobox têm sido alvo de intensas pesquisas científicas relacionadas ao câncer. Recentemente, mostramos que o gene homeobox TGIF1 está expresso no carcinoma epidermóide de boca na sua forma genérica. Porém, não foi feita uma discriminação entre quais variantes transcricionais, ou subtipos, do TGIF1 estariam expressas. Neste estudo, propusemo-nos a verificar diferenças na freqüência de expressão das variantes transcricionais do TGIF1 em carcinomas epidermóides de boca (CEB) em relação a tecidos morfologicamente não tumorais (TN), avaliar possíveis associações entre essas variantes nos pacientes portadores de CEB e relacionar o grau de expressão dessas variantes com aspectos clínicos, histológicos e com a sobrevida dos pacientes. Adicionalmente, procuramos analisar a expressão da proteína do TGIF1. Foram analisadas 48 amostras congeladas de CEB e 12 de TN. O RNA total de cada amostra foi extraído utilizando-se solução de TRizol®. Os transcritos do TGIF1 foram amplificados por RT-PCR para cada caso de CEB e TN utilizando-se inicialmente um par de iniciadores genéricos para todas as suas variantes. Após essa triagem, os casos positivos foram amplificados utilizando-se pares de iniciadores específicos para cada variante. Não houve diferença estatística entre a freqüência de expressão das variantes do TGIF1 nos grupos CEB e TN, porém as variantes 4 e 8 foram as que apresentaram p-valores menores. Dentro do grupo de CEB, houve associação significativa entre algumas variantes entre si (sete dos vinte e um cruzamentos), de forma que as variantes 1 e 4 foram as que mais tiverem associação com outras variantes. Dessa forma, optamos por prosseguir o estudo utilizando somente as variantes 1, 4 e 8. Não houve correlação entre a expressão das variantes selecionadas e variáveis clinicas e histológicas propostas. Em relação à sobrevida, a expressão das variantes 1 e 8 mostraram correlação univariada com o desfecho óbito, de maneira que o grupo de indivíduos que mais expressou ambas as variantes foi o que apresentou menor risco de óbito. Através da análise multivariada das variantes 1 e 8 e aspectos clínicos e histológicos, somente o tamanho da lesão e a invasão vascular sanguínea tiveram significado estatístico. A expressão protéica do TGIF1 foi analisada em 46 amostras parafinadas considerando-se a diferenciação celular, a graduação imunoistoquímica e o compartimento celular. Os resultados obtidos mostraram que as variantes do TGIF1 estão expressas diferentemente no grupo dos pacientes com CEB e sugerese que a expressão das variantes 1 e 8 estejam relacionadas, de maneira semelhante, a um menor risco de óbito para pacientes portadores de CEB. Adicionalmente, sugere-se que o tamanho da lesão e a invasão vascular sanguinea representem fatores de risco relevantes para o óbito de pacientes portadores de CEB. Sugere-se também que a expressão simultânea da proteína do TGIF1 tanto no núcleo quanto no citoplasma da célula esteja correlacionada a lesões pobremente diferenciadas. / Genes of the homeobox family have been the subject of intense scientific research related to cancer. Recently, we show that this gene is expressed in oral squamous cell carcinoma in its generic form. However, it was not made a discrimination between which transcript variants, or subtypes\", of TGIF1 were expressed. In this study, we aim to verify differences in the expression of the eight transcript variants described for the homeobox gene TGIF1 in oral squamous cell carcinomas (OSCC) related with morphologically non-tumoral tissues (NT), evaluate possible associations between these variants in patients with OSCC and relate the degree of expression of these variants with clinical, histological and survival aspects of patients. Additionally, we analyzed the expression of TGIF1 protein. It was analyzed 48 frozen samples of OSCC and 12 of NT. The total RNA from each sample was extracted using TRizol solution. TGIF1 transcripts were first amplified by RT-PCR for each case of OSCC and NT using a generic pair of primers. After these screening, the positive cases were amplified using specific pair of primers for each variant. There was no statistical difference between the frequency of expression of TGIF1 transcript variants in OSSC and NT groups, but the variants 4 and 8 had the lowest p-values. Within the OSCC group, there was a significant association between some variants among themselves (seven of the twenty-one associations), in a way that the variants 1 and 4 were the ones that had most association with other variants. Thus, we chose to continue the study using only variants 1, 4 and 8. There was no correlation between the expression of the selected variants with the clinical and histological aspects. Regarding survival, the expression of variants 1 and 8 showed statistical correlation with the outcome death, in a way that the group of patients that most expressed both variants was that one with the lower risk of death. By multivariate analysis of variants 1 and 8 and clinical and histological aspects, only the size of the lesion and vascular invasion blood were statistically significant. The protein expression of TGIF1 was analyzed in 46 paraffin-embedded tissues considering the cell differentiation, the immunohistochemistry graduation and the cell compartment. The results showed that the variants of TGIF1 are differently expressed in the OSCC group of patients and it is suggested that the expression of variants 1 and 8 may be related, in a similar way, to a lower risk of death for patients with OSCC. Additionally, it is suggested that the size of the lesion and the vascular invasion of blood represent relevant risk factors for death in patients with OSCC. It is also suggested that the simultaneous expression of TGIF1 protein not only in the nucleus but also in the cytoplasm of the cell is correlated with the poorly differentiated lesions of OSCC.

by Lam Mei Ling. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 127-137). / Abstract also in Chinese. / Acknowledgment --- p.I / Table of content --- p.II / List of figures --- p.VII / List of tables --- p.IX / Abbreviation --- p.X / Abstract --- p.XII / 論文摘要 --- p.XIII / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Acquired immunodeficiency syndrome --- p.1 / Chapter 1.1.1 --- Discovery of AIDS --- p.1 / Chapter 1.1.2 --- Definition and symptoms of AIDS --- p.1 / Chapter 1.1.3 --- AIDS transmission --- p.2 / Chapter 1.1.4 --- AIDS epidemic --- p.3 / Chapter 1.2 --- Human immunodeficiency virus --- p.3 / Chapter 1.2.1 --- Discovery of HIV --- p.3 / Chapter 1.2.2 --- The structure of HIV --- p.4 / Chapter 1.2.3 --- Genomic structure of HIV --- p.5 / Chapter 1.2.4 --- Life cycle of HIV --- p.5 / Chapter 1.2.5 --- How HIV is involved in different stages of AIDS --- p.7 / Chapter 1.3 --- Therapeutic targets for treatment of AIDS --- p.8 / Chapter 1.3.1 --- HIV reverse transcriptase (HIV RT) --- p.8 / Chapter 1.3.2 --- HIV integrase (HIV IN) --- p.11 / Chapter 1.3.3 --- HIV protease (HIV PR) --- p.12 / Chapter 1.3.4 --- Chemokine receptors --- p.14 / Chapter 1.3.5 --- Vaccine development --- p.16 / Chapter 1.4 --- AIDS therapy --- p.17 / Chapter 1.4.1 --- Current status of AIDS therapy --- p.17 / Chapter 1.4.1.1 --- Drugs approved by US Food & Drug Administration (FDA) --- p.17 / Chapter 1.4.1.2 --- Combination therapy --- p.19 / Chapter 1.4.1.3 --- Vaccine development --- p.19 / Chapter 1.4.2 --- Alternative treatment --- p.20 / Chapter 1.5 --- Objective of my project --- p.21 / Chapter Chapter 2 --- Screening of traditional Chinese medicinal (TCM) plants for HIV reverse transcriptase inhibition --- p.22 / Chapter 2.1 --- Introduction --- p.22 / Chapter 2.1.1 --- HIV RT structure and function --- p.22 / Chapter 2.1.2 --- Natural product against HIV RT --- p.25 / Chapter 2.1.3 --- Inhibitory activities from plant extracts --- p.27 / Chapter 2.2 --- Materials and Methods --- p.28 / Chapter 2.2.1 --- Materials --- p.28 / Chapter 2.2.2 --- Extraction methods --- p.30 / Chapter 2.2.2.1 --- Methanol extraction --- p.30 / Chapter 2.2.2.2 --- Hot water extraction --- p.30 / Chapter 2.2.2.3 --- Preparation of Prunella vulgaris extract --- p.30 / Chapter 2.2.3 --- Reverse transcriptase assay --- p.31 / Chapter 2.2.4 --- Characterization of active component in extract of Prunella vulgaris --- p.32 / Chapter 2.2.4.1 --- Protease digestion --- p.32 / Chapter 2.2.4.2 --- Glucosidase digestion --- p.32 / Chapter 2.2.4.3 --- Ethanol precipitation --- p.33 / Chapter 2.2.4.4 --- Sodium periodiate oxidization --- p.33 / Chapter 2.2.4.5 --- Polyvinylpyrrolidone (PVP) Precipitation --- p.34 / Chapter 2.2.4.6 --- Polyamide resin binding --- p.34 / Chapter 2.2.5 --- Purification of Prunella vulgaris extract --- p.34 / Chapter 2.2.5.1 --- Polyamide resin column chromatography --- p.34 / Chapter 2.2.5.2 --- Sephadex LH-20 chromatography --- p.35 / Chapter 2.2.5.3 --- Reverse phase HPLC chromatography --- p.36 / Chapter 2.2.6 --- Characterization of purified Prunella vulgaris extract --- p.37 / Chapter 2.2.6.1 --- Paper chromatography --- p.37 / Chapter 2.2.6.2 --- Acid hydrolysis of extract --- p.37 / Chapter 2.2.6.3 --- Thin layer chromatography --- p.38 / Chapter 2.2.6.4 --- Other assays --- p.39 / Chapter 2.2.7 --- Calculation --- p.40 / Chapter 2.3 --- Results --- p.41 / Chapter 2.3.1 --- Screening of Herbs --- p.41 / Chapter 2.3.1.1 --- Screening of methanol extracts --- p.41 / Chapter 2.3.1.2 --- Screening of hot water extracts --- p.41 / Chapter 2.3.2 --- Characterization of active components in Prunella vulgaris crude extracts --- p.44 / Chapter 2.3.2.1 --- Protease digestion --- p.44 / Chapter 2.3.2.2 --- Glucosidase digestion --- p.44 / Chapter 2.3.2.3 --- Ethanol precipitation --- p.44 / Chapter 2.3.2.4 --- Sodium periodate oxidation --- p.48 / Chapter 2.3.2.5 --- Effect of naturally occurring chemicals on inhibition of HIV RT --- p.48 / Chapter 2.3.2.6 --- Effect of removal of polyphenolic components of aqueous extract on inhibition of HTV RT --- p.51 / Chapter 2.3.3 --- Further purification of active components in aqueous extract of Prunella vulgaris --- p.53 / Chapter 2.3.3.1 --- Absorption chromatography by polyamide resin --- p.53 / Chapter 2.3.3.2 --- The Sephadex LH-20 chromatography --- p.53 / Chapter 2.3.3.3 --- Reverse phase high performance liquid chromatography --- p.56 / Chapter 2.3.3.4 --- Recovery of extract --- p.59 / Chapter 2.3.3.5 --- Inhibition from extract of various steps of purification --- p.59 / Chapter 2.3.4 --- Characterization of purified aqueous extract of Prunella vulgaris --- p.62 / Chapter 2.3.4.1 --- Paper chromatography --- p.62 / Chapter 2.3.4.2 --- Dose response curve --- p.62 / Chapter 2.3.4.3 --- Acid hydrolysis of purified extract --- p.68 / Chapter 2.3.4.4 --- Identification of monosaccharide in purified extract by Thin layer chromatography (TLC) --- p.71 / Chapter 2.3.5 --- Specificity of the purified extract on polymerase inhibition --- p.75 / Chapter 2.3.5.1 --- Inhibition of purified Prunella vulgaris extract on Taq polymerase --- p.75 / Chapter 2.3.5.2 --- Inhibition of purified Prunella vulgaris extract on Superscript II --- p.75 / Chapter 2.4 --- Discussion --- p.79 / Chapter Chapter 3 --- Screening of inhibitory activities from traditional Chinese medicinal (TCM) plants extracts to HIV protease --- p.86 / Chapter 3.1 --- Introduction --- p.86 / Chapter 3.1.1 --- HIV Protease structure and function --- p.86 / Chapter 3.1.2 --- Natural products against HIV Protease --- p.87 / Chapter 3.1.3 --- Plant extracts against HIV Protease --- p.89 / Chapter 3.2 --- Materials and Methods --- p.91 / Chapter 3.2.1 --- Materials --- p.91 / Chapter 3.2.2 --- Expression of HIV protease --- p.92 / Chapter 3.2.2.1 --- Expression and purification of HIV protease --- p.92 / Chapter 3.2.2.2. --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) --- p.94 / Chapter 3.2.3 --- Characterization of HIV protease --- p.95 / Chapter 3.2.3.1 --- HIV protease assay by fluorometric measurement --- p.95 / Chapter 3.2.3.2 --- HIV protease assay by using reverse phase high performance liquid chromatography --- p.96 / Chapter 3.3 --- Results --- p.98 / Chapter 3.3.1 --- Expression of HIV protease --- p.98 / Chapter 3.3.2 --- HIV protease assay --- p.98 / Chapter 3.3.2.1 --- Protease assay by using reverse phase HPLC --- p.98 / Chapter 3.3.2.2 --- Protease assay by fluorometric measurement --- p.98 / Chapter 3.3.3 --- Screening of crude Chinese medicinal extracts on inhibition of HIV protease --- p.104 / Chapter 3.3.3.1 --- Methanol extracts --- p.104 / Chapter 3.3.3.2 --- Water extracts --- p.105 / Chapter 3.3.4 --- Characterization of herbal extracts on inhibition of HIV protease --- p.110 / Chapter 3.3.4.1 --- Dose response curve of methanol extract of Woodwardia unigemmata --- p.110 / Chapter 3.3.4.2 --- Dose response curve of hot water extract of Prunella vulgaris --- p.110 / Chapter 3.3.4.3 --- Inhibition mode of methanol extract of Woodwardia unigemmata --- p.113 / Chapter 3.3.4.4 --- Inhibition mode of hot water extract of Prunella vulgaris --- p.113 / Chapter 3.3.4.5 --- Effect of partially purified extracts on HIV protease inhibition --- p.116 / Chapter 3.4 --- Discussion --- p.119 / Chapter Chapter 4 --- General discussion --- p.124 / References --- p.127 / Appendix / Appendix 1 Pictures of herbs used in this study --- p.i / Appendix 2 Mass spectrometry of purified Prunella vulgaris extract --- p.vi / Appendix 3 Calibration curve for determination of HIV PR concentration --- p.viii