A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science Johannesburg, 2017 / Cancer is characterised by abnormal cell proliferation and is one of the leading causes of death in first world countries and the second leading cause in developing countries. In 2012 alone, over 14 million cases were reported and over 8 million deaths were attributed to cancer worldwide, with sub-Saharan Africa, especially South Africa having one of the highest oesophageal cancer rates in the world. An important aspect of cancer is the telomeres, which are 10-15kbp of TTAGGG DNA repeats in humans at the ends of chromosomes. These repeats are maintained by the enzyme telomerase. Up to 90% of all cancers show increased telomerase activity to overcome the "end-replication" problem in which the telomeres shorten after each cell division. This eventually leads to cellular senescence. Due to the high number of cancers relying on increased telomerase activity to bypass senescence, telomerase could be a viable target for anti-cancer therapies. The limiting factor of the multi-subunit telomerase enzyme is its telomerase reverse transcriptase component (hTERT). hTERT has also been shown to migrate to the mitochondria during times of high oxidative stress caused by reactive oxygen species (ROS). Here it confers protection to the mitochondria against ROS, potentially preventing the cell form undergoing apoptosis and reaching senescence. This can potentially be detrimental, as cells become damaged by the ROS and continue dividing. This could lead to further genetic damage. Metformin, a drug used for the treatment of type-2 diabetes, has been linked to lower incidences of cancer. The mode of action of metformin is not yet fully understood, however it is known that it affects the mitochondria. Since hTERT and metformin could co-localise, the drug may influence hTERT and potentially telomerase activity. This makes metformin an anticancer candidate to be used in conjunction with traditional anticancer therapies. To determine telomerase activity in metformin treated oesophageal carcinoma cells, qPCR based telomerase activity assays must be used. These assays can be very expensive and time consuming, so a faster and cheaper alternative would be beneficial. Therefore, the aim of this project was to alter and improve a nanoparticle based detection method for telomerase activity, by decreasing the time required to prepare the DNA functionalised nanoparticles as well as determining a more rapid method of data measurement, and compare it to conventional qPCR based techniques (TRAPeze RT Telomerase Activity Kit – Merck). Thereafter the effects of the metformin treatment on telomere dynamics, such as telomere length, telomerase activity and hTERT mRNA expression, in oesophageal squamous carcinoma cells were determined. Gold nanoparticles were synthesised and functionalised with thiolated-DNA (telomerase substrate). These functionalised particles were characterised using transmission electron microscopy. To assess telomerase activity the extracted protein was added to the functionalised nanoparticle solution and allowed to elongate the coupled DNA. A characteristic of gold nanoparticles is that the size of the particles as well as their proximity to one another determines the colour of the nanoparticle solution. Due to the steric hindrance caused by the now elongated DNA, a distinct colour change was observable. The change in absorption spectra of the nanoparticle solution was recorded after the enzyme elongated the substrate. This nanoparticle based assay was then compared to TRAPeze RT Telomerase detection kit (Merck-Millipore) as a positive control. Using the conventional qPCR based telomerase activity assay, it was found that metformin significantly decreased telomerase activity in oesophageal cancer cell lines, however this was not seen using the nanoparticle assay. A colour change was observed with the nanoparticle assay compared to the negative control reflecting detection of telomerase activity. However, no significant decrease in telomerase activity could be detected due to metformin treatment. More optimisation is required, however this technique has great potential, as nanoparticle based assays are also known for their high sensitivity. This technique is also far more rapid and significantly cheaper that the qPCR based method. The gold nanoparticle based telomerase activity assay could become an alternative to conventional qPCR based techniques. / MT2018

O carcinoma oral de células escamosas (OSCC Oral Squamous Cell Carcinoma) é o câncer de cabeça e pescoço mais comum. Somente no Brasil, foram estimados 14.160 novos diagnósticos para o ano de 2009. O HPV está associado com o aumento no risco do câncer oral, mas seu papel na carcinogênese ainda é controverso. A BubR1, uma proteína importante para o checkpoint de fuso mitótico (SAC Spindle Assembly Checkpoint), tem sido associada com algumas proteínas codificadas por espécies virais e com o câncer. O objetivo do presente estudo foi avaliar a expressão de BubR1 em lesões orais benignas e amostras de OSCC com e sem metástase associadas com infecção pelo HPV. Nós realizamos imunoistoquímica para BubR1 em 16 biópsias de lesão oral benigna e em 70 biópsias de OSCC divididas em três grupos (tumores in situ, tumores invasivos sem metástase e tumores invasivos com metástase), com os respectivos linfonodos das amostras com metástase. A técnica de Nested PCR foi realizada com finalidade de detectar DNA do HPV. Nas lesões malignas, foi observada uma significante superexpressão de BubR1 associada com menor sobrevida (p = 0.0479). Houve também correlação significante (r = 1.000) de BubR1 entre as lesões com metástase e seus respectivos linfonodos. Noventa por cento dos OSCC e 100% das lesões benignas foram HPV positivos. HPV 16 e HPV 18 foram detectados em, respectivamente, 13% e 24% das amostras com OSCC HPV-positivas. O HPV teve maior prevalência (76%) nas amostras com alta expressão de BubR1 e a ausência de DNA viral não influenciou no padrão de expressão de BubR1. Esses resultados sugerem uma provável associação do HPV com a superexpressão de BubR1 em OSCC, o que não se aplica para lesões orais benignas. / Oral squamous cell carcinoma (OSCC) is the most common head and neck cancer. Only in Brazil, the estimate is that 14,160 new diagnoses will be made in 2009. HPV is associated with increasing risk of oral cancer, but its role in carcinogenesis is still controversial. BubR1, an important protein in the mitotic Spindle Assembly Checkpoint (SAC), has been associated with some virus-encoded proteins and cancer. The aim of the present study was to evaluate the expression of BubR1 in non-malignant oral lesions and OSCC with and without metastasis associated with HPV infection. We performed immunohistochemistry for BubR1 in 16 non-malignant oral lesion biopsies and in 70 OSCC biopsies divided into three groups (in situ tumors, invasive tumors without metastasis and invasive tumors with metastasis) with their respective lymph nodes from samples with metastasis. Nested PCR was performed in order to detect HPV DNA. Significantly higher BubR1 expression associated with shorter survival (p = 0.0479) was observed in malignant lesions. There was also a significant correlation (r = 1.000) with BubR1 expression in lesions with metastasis and their lymph nodes. Ninety percent of OSCC and 100% of benign lesions were HPV positive. HPV 16 and HPV 18 were present in 13% and 24% of HPV-positive OSCC samples, respectively. HPV was more prevalent (76%) in samples with high BubR1 expression and the absence of viral DNA had no influence on BubR1 expression. These findings suggest that HPV could be associated with overexpression of BubR1 in OSCC, but not in benign oral lesions.

Le carcinome rénal représente 5% des tumeurs de l’adulte et se développe au niveau des tubules rénaux. Le sous-type histologique majeur des cancers du rein est le carcinome rénal à cellules claires (cRCC). 90% des cRCC présentent une inactivation biallélique du gène suppresseur de tumeur de Von Hippel Lindau (VHL) induisant une activation constitutive de la voie de l’hypoxie via le facteur de transcription HIF1-α (Hypoxia Inducible Factor) qui contribue à la physiologie des tumeurs. Les cRCC sont des tumeurs à la fois radio- et chimiorésistantes, rendant la prise en charge thérapeutique des patients très difficile.Nos recherches consistaient en l’étude des rôles de la mucine membranaire MUC1, dont la queue cytoplasmique (MUC1 CT) peut interagir avec différentes voies de signalisation et agir en tant que co-activateur transcriptionnel de nombreux gènes impliqués dans la progression tumorale et la diffusion métastatique. Des travaux antérieurs réalisés au laboratoire montraient que la surexpression de MUC1 observée dans les cRCC était associée au statut métastatique des patients et marquait un mauvais pronostic. Cette surexpression de MUC1 est également impliquée dans la voie de l’hypoxie, voie majeure de la carcinogenèse rénale. Le premier objectif de l’étude était donc de déterminer les effets de la surexpression de MUC1 sur les propriétés des cellules de cRCC. Nous montrons ainsi que le domaine extracellulaire de MUC1 ainsi que sa partie cytoplasmique sont impliqués dans l’augmentation des capacités migratoires et de la viabilité des cellules cancéreuses rénales et qu’elle leur confère une résistance à l’anoïkis, programme de mort cellulaire déclenché lorsque la cellule perd ses contacts avec les cellules voisines ou avec la matrice extra-cellulaire et diminuent les propriétés d’agrégation des cellules tumorales. Nous montrons également que MUC1 est impliquée dans la chimiorésistance des cRCC en induisant l’expression de genes de chimiorésistance comme ABCG2 et GSTO2. Nous montrons par ailleurs que les propriétés invasives des cellules de cRCC sont exclusivement liées à MUC1 CT. Le deuxième objectif de l’étude était d’identifier les mécanismes moléculaires à l’origine du clivage de MUC1 CT. En utilisant différentes stratégies (siARN, inhibiteurs pharmacologiques et peptides), nous montrons pour la première fois que deux sheddases, ADAM10 et ADAM17 et la gamma secrétase sont nécessaires au clivage de MUC1 C, permettant ainsi sa délocalisation nucléaire et l’augmentation des propriétés invasives des cellules de cRCC. Enfin, nous montrons que la surexpression de MUC1 augmente l’expression protéique d’ADAM10/17, suggérant une boucle de régulation positive existant en conditions pathologiques.En conclusion, notre étude souligne le rôle de MUC1 dans la progression tumorale rénale et montre que la localisation nucléaire de MUC1-C est à l’origine de l’acquisition d’un phénotype invasif et chimiorésistant via l’action des sheddases ADAM10/17 et de la gamma secrétase. MUC1 apparait alors comme une cible thérapeutique potentielle intéressante dans la prise en charge des cRCC. / Renal cell carcinoma corresponds to 5% of all adult malignancies and originates from renal tubules. The main histologic subtype is represented by clear renal cell carcinoma. Ninety percent of cRCC present a biallelic inactivation of the von Hippel Lindau (VHL) tumor suppressor gene resulting in constitutive activation of hypoxia signaling pathway via the Hypoxia Inducible Factor (HIF) -1 transcription factor that contributes to the physiology of tumours. cRCC is typically highly resistant to conventional systemic therapies. MUC1 is a membrane-anchored mucin and its cytoplasmic tail (CT) can interact with many signaling pathways and act as a co-transcription factor to activate genes involved in tumor progression and metastasis. Previous studies have shown that MUC1 is diffusely overexpressed in cRCC and MUC1 overexpression has been found to be associated with metastatic disease and a worse prognosis.MUC1 is overexpressed in renal cell carcinoma with correlation to prognosis and has been implicated in the hypoxic pathway, the main renal carcinogenetic pathway. In this context, we assessed the effects of MUC1 overexpression on renal cancer cells properties. Using shRNA strategy and/or different MUC1 constructs, we found that MUC1-extracellular domain and MUC1 CT are both involved in increase of migration, cell viability, resistance to anoikis and to decrease of cell aggregation in cancer cells. We also showed that MUC1 is involved in cRCC chemoresistance by inducing chemoresistance genes expression like ABCG2 and GSTO2. Invasiveness depends only on MUC1 CT. Then, by using siRNA strategy and/or pharmacological inhibitors or peptides, we showed that sheddases ADAM10, ADAM17 and gamma-secretase are necessary for MUC1 C-terminal subunit (MUC1-C) nuclear location and in increase of invasion property. Finally, MUC1 overexpression increases ADAM10/17 protein expression suggesting a positive regulatory loop. In conclusion, we report that MUC1 acts in renal cancer progression and MUC1-C nuclear localization is driving invasiveness of renal cancer cells through a sheddase/gamma secretase dependent pathway. MUC1 appears as a therapeutic target by blocking MUC1 cleavage or nuclear translocation by using pharmacological approach and peptide strategies.

Mutations in RHBDF2, the gene encoding inactive rhomboid protein iRHOM2, result in the dominantly inherited condition Tylosis with oesophageal cancer (TOC). TOC causes plamoplantar keratoderma, oral precursor lesions and up to a 95 % life-time risk of oesophageal squamous cell carcinoma (SCC). The role of iRHOM2 in the epidermis is not well characterised, although we previously showed dysregulated epidermal growth factor receptor (EGFR) signalling and accelerated migration in TOC keratinocytes, and a role for iRHOM2 was shown in trafficking the metalloproteinase ADAM17. Substrates of ADAM17 include EGFR ligands and adhesion molecules. iRHOM2 localisation and function were investigated in frozen sections and keratinocyte cell lines from control and TOC epidermis. Although iRHOM2 was predicted to be an ER-membrane protein, it showed cell-surface expression in control epidermis, with variable localisation in TOC. Increased processing and activation of ADAM17 was seen in TOC keratinocytes compared with control cells, suggesting that increased ADAM17-mediated processing of EGFR ligands may cause the changes in EGFR signalling. Downstream of iRHOM2-ADAM17, Eph/Ephrin and NOTCH signalling also appeared affected. Additionally, desmosomes in TOC epidermis lacked the electron-dense midline of the mature desmosomes seen in normal skin; this was accompanied by increased processing of desmoglein 2, a substrate of ADAM17. Expression and localisation of iRHOM2 was also investigated in TOC and sporadic SCC. iRHOM2 expression varied between SCC cell lines, and appeared to correlate with ADAM17 and NOTCH1 expression in oesophageal SCC and head and neck SCC cells. In summary, iRHOM2 mutations in TOC appear to be gain-of-function in nature, resulting in increased ADAM17 processing and enhanced EGFR signalling. Questions remaining include the reason why iRHOM2 is found at the plasma membrane. Future study of the iRHOM2-ADAM17 pathway may provide additional insight into the mechanism of epidermal wound healing and the pathogenesis of oesophageal SCC.

Desmoglein 3 (Dsg3) belongs to the desmoglein subfamily and functions as an adhesion molecule in desmosomes. Two pools of Dsg3 have been identified, detergent soluble and insoluble proteins. Recent studies show that DSG3 is upregulated in squamous cell carcinoma (SCC). However, its biological function in cancer remains poorly understood. The aim of this study was to investigate the extra-junctional functions of Dsg3, in particular its roles in signalling that regulates cell morphology and locomotion in cancer cells. This study adopted a unique cancer cell model with Dsg3 gain-of-function and has discovered two novel regulatory signal pathways that may play a crucial role in the control of cell invasion and metastasis in Dsg3 associated cancers. Firstly, Dsg3 regulates the phosphorylation of Ezrin at Thr567 in a PKCdependent manner that is crucial for its activation and regulation of actin based membrane projections and accelerated cell locomotion in SCC. Secondly, Dsg3 modulates the transcriptional activity of cJun:AP1 that is responsible for regulating a cohort of genes to confer an invasive phenotype. It is likely that these two pathways are closely linked in that the Dsg3-mediated activation of cJun:AP1 elicits PKCdependent Ezrin activation that in turn enable it to form a complex with Dsg3 at the plasma membrane to promote membrane projection and cell locomotion. Several lines of evidence support these conclusions: Dsg3 forms a complex with Ezrin at the plasma membrane and induces phosphorylation of Ezrin resulting in augmented membrane protrusions and cell migration. Dsg3 silencing inhibits junction formation concomitant with collapse of membrane protrusion. Furthermore, Dsg3 regulates the activity of cJun:AP1. Collectively, these findings provide new insight regarding Dsg3 in cancer, suggesting it acts as a key regulator of cell invasion and metastasis in SCC. Therefore, targeting Dsg3 could be a potential new strategy in the control of cancer progression and metastasis.

Periocular malignancy represents an increasing burden and currently requires disfiguring surgery in an attempt to cure patients. Basal cell carcinoma (BCC) is the commonest cancer worldwide and morphoeic BCC (mBCC) is an aggressive subtype. Sebaceous gland carcinoma (SGC) is a rare, but life-threatening condition that often requires blinding surgery to prevent mortality, especially in the pagetoid subtype. MBCC has a high risk of local recurrence compared to the more indolent nodular subtype reflected by a different set of driver genes including FLNB and HECTD4. Surrounding mBCC stroma is abnormal, containing mutations in EPHA3 and GLI3. Four common dysregulated pathways detected using both whole exome and RNA sequencing for mBCC were; 'hedgehog (Hh) signalling pathway', 'BCC', 'Natural killer cell mediated cytotoxicity' and 'Fc Epsilon RI signalling pathway'. Hh mutational profile for nodular BCC was not reflected in the RNA and protein expression. In contrast, Hh overexpression is seen in the tumour and stroma of morphoeic tissue with the latter potentially being partly responsible for its aggressive nature and risk of recurrence that may warrant removal to prevent recurrence. SGC has a low overall mutational burden, no UV signature and defective mismatch repair signature. Driver genes included TP53, RB1 and the dynein family is a novel driver possibly involved in chromatid segregation as marked chromosomal instability was demonstrated on copy number analysis. Correlation of whole exome and RNA sequencing data demonstrated upregulated 'cell cycle', 'ubiquitin mediated proteolysis' and 'wnt signalling'. Subtype analysis of pagetoid and nodular SGC revealed the histone gene cluster family as important to both. Oncomir hsa-miR-21 was overexpressed in both and loss of hsa-miR-199a occurs in pagetoid. Increased protein expression of HIST1H2BD was seen in both subtypes as was Hh expression. These novel SGC findings support a chromosomally unstable cancer with the ability to invade extracellular matrix.

Kindlin-1 (Kin1) is an epithelial focal adhesion protein that plays a key role in integrin-mediated anchorage of cells to the extracellular matrix. Congenital loss of Kin1 leads to Kindler Syndrome (KS), whose symptoms include progressive epidermal atrophy, reduced keratinocyte proliferation, skin blistering and increased incidence of aggressive Squamous Cell Carcinoma (SCC). Objectives of this study were to examine the role of Kin1 in skin homeostasis and in the development of aggressive SCC in KS, as the molecular aetiologies for these pathologies are yet to be clearly understood. We first examined whether the recently discovered role of Kin1 in mitosis contributes to reduced keratinocyte proliferation observed in KS epidermis. We discovered that short-term loss of Kin1 in adult mouse epidermis reduced keratinocyte proliferation. We also found that Kin1 loss increased mitotic spindle misorientation that, according to the model of cell division in skin homeostasis, decreases cell proliferative potential, and, thus, may account for the reduced proliferation in our model. As spindle misorientation can stem from microtubule instability, we believe that the reduction in acetylated α-tubulin (ac-tub), a known marker of stable microtubules, that we also observed in mouse epidermis following Kin1 loss could account for the defective spindle orientation phenotype. The role of Kin1 in spindle orientation was also evident in vitro. Moreover, data from our lab revealed showed reduction in spindle ac-tub following Kin1 depletion, mirroring our in vivo observation. Additionally to orientation defects, in vitro depletion of Kin1 led to enhanced chromosome missegregation, which is likely to result from reduced microtubule stability due to low levels of ac-tub. We showed that role of Kin1 in spindle orientation and chromosome segregation is dependent on HDAC6, a known inhibitor of ac-tub. Overall, our results uncover an in vitro and in vivo role of Kin1 in mitotic spindle fidelity that could be crucial to skin homeostasis, and, when disturbed, may lead to reduced keratinocyte proliferation. Interestingly, our in vitro studies also revealed that in mitosis Kin1 and Kindlin-2 (Kin2) had overlapping, but also distinct roles, which is in line with various reports that show different biological functions for the two protein isoforms. Our next and final aim was to explore the roles of Kin1 in the development and progression of SCC, which would help us comprehend the reason behind the cancer's aggressive nature in KS. By employing in vitro and in vivo SCC growth assays and tumour immunohistochemical staining we found that absence of Kin1 in SCC cells and tumours enhanced proliferation and growth, and enhanced tumour vascularisation. RNA sequencing of tumour material revealed that lack of Kin1 increased expression of matrix metalloproteinases and chemokines, which have been implicated in tumour progression via promotion of angiogenesis and invasion in a plethora of studies, and of various angiogenesis markers. Together this provides an insight into the mechanisms via which Kin1 controls tumour microenvironment and, ultimately, SCC tumour growth and development. Overall, we report an in vitro and in vivo role for Kin1 in mitotic spindle stability, which affects a variety of mitotic processes and may be linked to reduced keratinocyte proliferation observed in epidermis of KS patients, thus contributing to skin homeostasis. Moreover, we describe a role for Kin1 in regulation of SCC tumour growth and progression, which may ultimately offer an explanation for the aggressive and life-threatening nature of SCC developed in KS.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Angiogenesis is the development of new blood vessels from pre-existing capillaries, being an essential step in tumor growth for supplying nutrition and oxygen to cells in proliferation. A cell that may be involved in this process is the mast cell (MC), since besides the defense function, acts in the blood vessels regulation. The MC participation in the induction of angiogenesis has been suggested in various malignant tumors. The purposes of this study was to evaluate angiogenesis and mast cell density in oral epithelial dysplasia and squamous cell carcinoma (SCC). This is an observational, retrospective and quantitative study using the sample selection from the archives of the Department of Legal Medicine and Pathology and Laboratory of Oral Pathology, both from the Federal University of CearÃ. For MC evaluation , the sample was consisted of 73 paraffin blocks, distributed between SCC (n=30), epithelial dysplasia (n=23) and hyperplasias fibroepithelial (HFE) (n = 20), as control, and for angiogenesis the sample was 65 blocks, consisted of 24 SCC, 19 epithelial dysplasias and 22 HFE. Immunohistochemistry was performed using the MC-tryptase, CD31 and CD34 antibodies. For quantification, digital images were captured and then counting was performed using Image J software. The antibody staining percentage was determined using SAMM software. With regard to mast cells, there was a lower density in malignant lesions in relation to HFE and dysplasia (p = 0.0092). Evaluating angiogenesis, CD31 expression showed differences between epithelial dysplasia and SCC and between SCC and HFE, with a greater percentage of vessels in SCC (p <0.0001). However, CD34 expression did not differ between groups. The CD31 antibody was shown to be a better angiogenesis marker in oral mucosa than CD34. Increased vascularity in oral squamous cell carcinoma suggests that angiogenesis is necessary for tumor growth, increasing when the malignant transformation starts. However, no correlation was found between mast cells and angiogenesis. / AngiogÃnese à o surgimento de um novo vaso sanguÃneo a partir de capilares prÃ-existentes, sendo um passo essencial no crescimento tumoral por fornecer nutriÃÃo e oxigÃnio Ãs cÃlulas em proliferaÃÃo. Uma cÃlula que pode estar envolvida nesse processo à o mastÃcito, pois, alÃm da funÃÃo de defesa, atua na regulaÃÃo de vasos sanguÃneos. Sua participaÃÃo na induÃÃo da angiogÃnese tem sido sugerida em vÃrios tumores malignos. Os objetivos deste trabalho foram avaliar a angiogÃnese e a densidade de mastÃcitos em displasias epiteliais e no carcinoma espinocelular (CEC) de boca. Trata-se de um estudo observacional, retrospectivo e quantitativo, realizado atravÃs da seleÃÃo de amostra proveniente dos arquivos do Departamento de Patologia e Medicina Legal e do laboratÃrio de Patologia Bucal do curso de Odontologia, ambos da Universidade Federal do CearÃ. Para a avaliaÃÃo dos mastÃcitos, a amostra foi constituÃda por 73 blocos parafinados, distribuÃdos entre CEC (n=30), displasias epiteliais (n=23) e hiperplasias fibroepiteliais (HFE) (n=20), como controle, e para a angiogÃnese a amostra foi de 65 blocos, sendo 24 de CEC, 19 de displasias epiteliais e 22 de HFE. Foi realizada imunohistoquÃmica utilizando-se os anticorpos anti-triptase, para mastÃcitos e anti-CD31 e anti-CD34, para vasos sanguÃneos. Para quantificaÃÃo, foram capturadas imagens digitais e, em seguida, utilizados softwares para auxiliar na contagem dos mastÃcitos (Image J) e para determinaÃÃo do percentual de marcaÃÃo do anticorpo (SAMM). Com relaÃÃo aos mastÃcitos, houve menor densidade destes nas lesÃes malignas em relaÃÃo Ãs HFE e displasias (p=0,0092). Avaliando angiogÃnese, a expressÃo de CD31 mostrou diferenÃa entre os grupos CEC e displasia epitelial e entre CEC e HFE, havendo um maior percentual de vasos nos CEC (p<0,0001). Contudo, o CD34, nÃo mostrou diferenÃa entre os grupos. O anticorpo CD31 mostrou-se melhor marcador de angiogÃnese em mucosa oral do que CD34. O aumento da vascularizaÃÃo em CEC oral sugere que a angiogÃnese à necessÃria ao crescimento tumoral, aumentando à medida que inicia o processo de malignizaÃÃo. NÃo foi encontrada correlaÃÃo entre mastÃcitos e angiogÃnese.

O carcinoma oral de células escamosas (OSCC Oral Squamous Cell Carcinoma) é o câncer de cabeça e pescoço mais comum. Somente no Brasil, foram estimados 14.160 novos diagnósticos para o ano de 2009. O HPV está associado com o aumento no risco do câncer oral, mas seu papel na carcinogênese ainda é controverso. A BubR1, uma proteína importante para o checkpoint de fuso mitótico (SAC Spindle Assembly Checkpoint), tem sido associada com algumas proteínas codificadas por espécies virais e com o câncer. O objetivo do presente estudo foi avaliar a expressão de BubR1 em lesões orais benignas e amostras de OSCC com e sem metástase associadas com infecção pelo HPV. Nós realizamos imunoistoquímica para BubR1 em 16 biópsias de lesão oral benigna e em 70 biópsias de OSCC divididas em três grupos (tumores in situ, tumores invasivos sem metástase e tumores invasivos com metástase), com os respectivos linfonodos das amostras com metástase. A técnica de Nested PCR foi realizada com finalidade de detectar DNA do HPV. Nas lesões malignas, foi observada uma significante superexpressão de BubR1 associada com menor sobrevida (p = 0.0479). Houve também correlação significante (r = 1.000) de BubR1 entre as lesões com metástase e seus respectivos linfonodos. Noventa por cento dos OSCC e 100% das lesões benignas foram HPV positivos. HPV 16 e HPV 18 foram detectados em, respectivamente, 13% e 24% das amostras com OSCC HPV-positivas. O HPV teve maior prevalência (76%) nas amostras com alta expressão de BubR1 e a ausência de DNA viral não influenciou no padrão de expressão de BubR1. Esses resultados sugerem uma provável associação do HPV com a superexpressão de BubR1 em OSCC, o que não se aplica para lesões orais benignas. / Oral squamous cell carcinoma (OSCC) is the most common head and neck cancer. Only in Brazil, the estimate is that 14,160 new diagnoses will be made in 2009. HPV is associated with increasing risk of oral cancer, but its role in carcinogenesis is still controversial. BubR1, an important protein in the mitotic Spindle Assembly Checkpoint (SAC), has been associated with some virus-encoded proteins and cancer. The aim of the present study was to evaluate the expression of BubR1 in non-malignant oral lesions and OSCC with and without metastasis associated with HPV infection. We performed immunohistochemistry for BubR1 in 16 non-malignant oral lesion biopsies and in 70 OSCC biopsies divided into three groups (in situ tumors, invasive tumors without metastasis and invasive tumors with metastasis) with their respective lymph nodes from samples with metastasis. Nested PCR was performed in order to detect HPV DNA. Significantly higher BubR1 expression associated with shorter survival (p = 0.0479) was observed in malignant lesions. There was also a significant correlation (r = 1.000) with BubR1 expression in lesions with metastasis and their lymph nodes. Ninety percent of OSCC and 100% of benign lesions were HPV positive. HPV 16 and HPV 18 were present in 13% and 24% of HPV-positive OSCC samples, respectively. HPV was more prevalent (76%) in samples with high BubR1 expression and the absence of viral DNA had no influence on BubR1 expression. These findings suggest that HPV could be associated with overexpression of BubR1 in OSCC, but not in benign oral lesions.

Philosophiae Doctor - PhD / Purpose: High risk human papillomavirus (HR-HPV) is well established as a causative agent of squamous cell carcinoma (SCC) of the orophaynx. HR-HPV has also been reported in periocular cancers and precancers, but controversy exists about its overall incidence and clinicopathologic profile. The purpose of this study is to evaluate the role of HR-HPV infection in periocular cancers and precancers, using multiple methods of detection. Design: Retrospective observational case series with laboratory investigations. Methods: Sequential surgical samples of 87 carcinomas (invasive SCC, SCC in situ and sebaceous carcinoma) from three different periocular sites (conjunctiva, lacrimal sac and the eyelid) diagnosed over a 15-year period (2000-2015) were selected for evaluation. Unstained paraffin sections of 87 cases of periocular carcinomas were analyzed with immunohistochemistry (IHC) for p16 as a screening test. p16 positive conjunctival- and lacrimal sac SCC were further evaluated for HR-HPV using DNA in situ hybridization (DNA ISH), and a subset was also analyzed by DNA Polymerase Chain Reaction (DNA PCR). p16 positive periocular sebaceous carcinomas (SC) were analyzed with PCR, and a subset of 18cases was further studied with a novel method of mRNA ISH, an advanced technique with an enhanced sensitivity and specificity. Relevant patient clinical information was obtained from review of the electronic medical records.