Cancer is a highly complex disease that evolved in response to a wide range of biological and molecular changes that impact disease behaviour, treatment efficacy and clinical outcomes. Studying this diversity in human tumours is essential for gaining insights that will ultimately improve the survival rates of cancer patients. Cancer stem-like cells (CSCs) are believed to be responsible for invasive and metastatic features in tumours and can contribute to chemotherapy resistance and subsequent tumour relapses. There is an increasing need to identify the molecular mechanisms involved in tumour cells, particularly in CSCs. Cancer testis antigens (CTAs) are a subclass of germline proteins normally produced in immune-privileged sites, such as the testis, ovary and placenta of somatic tissues, and the presence of these antigens is increased in a variety of cancers. These characteristics make CTAs highly important immunotherapeutic targets, since they do not harness the immune response in the testes but encode immunogenic proteins that can induce a specific response in cancerous tissues. CTA genes are potentially very importance in clinical applications, including cancer diagnosis, vaccination and immunotherapy. This current study focused on the investigation of two CTAs, TDRD12 and LKAAEAR1, that may have an enhanced presence in cancer and the potential to be immunogenic. TDRD12 is linked to stemness features and enables the proliferation of germ line tumour cells. It appears to act as a possible transcriptional regulator for germline factors that are essential to cell cycle proliferation, germ cell maintenance and stem marker expression. TDRD12 may have the potential to drive oncogenesis and CSC targets. LKAAEAR1 was validated as a CTA at the protein level, showing its production was restricted to germ cells and the central nervous system from normal tissues and showed aberrant production in a wide range of tumours. This protein has been shown to be produced in germ cells undergoing spermatogenesis with strong nuclei staining, suggesting its potential role in this process. LKAAEAR1 potentially acts as a regulator for transposable elements, thereby increasing its contributions to cancer development. This study demonstrated that LKAAEAR1 could potentially be used as a cancer biomarker and therapeutic target.

Made available in DSpace on 2015-07-22T20:50:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-25 / Os antígenos cancer/testículo (CTAs) são considerados promissores alvos para abordagens de imunoterapia em câncer devido à sua alta imunogenicidade e padrão de expressão praticamente restrito a tecidos tumorais (estão também expressos em células germinativas do testículo, placenta e ovário fetal). Apesar do padrão de expressão dos CTAs estar bem estabelecido em carcinomas, pouco se sabe sobre a expressão desses antígenos em neoplasias linfóides como Linfomas de Hodgkin (LH) e Linfomas não-Hodgkin (LNH). Objetivo: Avaliar o potencial desses antígenos específicos tumorais como candidatos à imunoterapia em linfomas, através da análise de expressão protéica dos CTAs e avaliação da resposta imune humoral espontânea contra esses antígenos, correlacionando os achados com os dados clínicos e prognóstico. Métodos: Três blocos de Tissue Microarray (TMA) foram construídos a partir de 38 amostras teciduais de LH clássico e 106 de LNH obtidos nos arquivos do Departamento de Anatomia Patológia da UNIFESP. As lâminas de TMA foram submetidas a um painel de imunohistoquímica para 9 CTAs, a saber: MAGE-A1, MAGE-A3, MAGE-A4, MAGE-A10, CT7, CT10, NY-ESO-1, LAGE e GAGE. A avaliação da imunidade humoral espontânea foi realizada em 97 amostras de soro de pacientes com LNH ao diagnóstico (59 dos quais foram incluídos na casuística do TMA), utilizando-se a técnica de ELISA em um painel mais amplo de CTAs (MAGEA1, MAGE-A3, MAGE-A4, MAGE-A10, NY-ESO-1, CT7, CT10, CT24, CT45, CT46, CT47, CT63, CT83, SSX-1, SSX-2, SSX-4, LAGE-1, GAGE-2, SAGE-1, XAGE-1). Resultados: De forma global, houve baixa expressão de CTAs nas amostras analisadas, visto que apenas 21,1% das amostras de LH e 11,3% das amostras de LNH apresentaram positividade para pelo menos 1 dos CTAs incluídos no painel de imunohistoquímica. MAGE-A (18,4%) e CT7 (13,2%) foram os CTAs mais frequentemente expressos em LH, enquanto MAGE-A (6,6%), GAGE (5,7%) e NY-ESO-1 (4,8%) foram os mais expressos em LNH. Apesar de não ter sido encontrada diferença estatisticamente significante na expressão de CTAs entre os subgrupos clínicos de LH, houve maior frequência de positividade nos pacientes com estadiamento avançado (28,6%), comparado àqueles com estadiamento inicial (11,8%). Nos subgrupos clínicos de LNH, a frequência de expressão de CTAs foi maior nos linfomas agressivos (14,9%) em relação aos indolentes (3,1%), nos linfomas difusos de grandes células B (LDGCB) (16,1%) comparado aos não-LDGCB (6,0%) e no subgrupo que não atingiu resposta completa (15,0%) comparado àqueles que obtiveram resposta completa (6,8%). Entretanto, as diferenças não foram estatisticamente significantes em nenhum desses subgrupos. Um achado inesperado no presente estudo foi a expressão mais frequente de CTAs no subgrupo de LNH com estadiamento inicial (I e II) comparado ao subgrupo com estadiamento avançado (III e IV). Apesar da diferença encontrada na análise de sobrevida entre o grupo de pacientes que não apresentaram expressão de CTA (sobrevida mediana de 65 meses) e aqueles que apresentaram expressão de pelo menos 1 CTA (sobrevida mediana de 11 meses), a diferença não foi estatisticamente significante (p=0.0947). A resposta humoral espontânea contra pelo menos 1 CTA do painel foi encontrada em 19,6% dos pacientes com LNH. CT47 foi o CTA mais frequentemente expresso (7.2%), seguido do CT45 (5.1%), NY-ESO-1 (5.1%) e MAGE-A4 (5.1%). Os CTAs foram mais frequentemente expressos em LNH de células B (21.2%) comparado aos LNH de células T (6.2%) (p=0.048). Não houve diferença estatisticamente significante na resposta humoral anti-CTAs em qualquer dos outros subgrupos clínicos de LNH. Conclusão: De forma geral, houve baixa expressão protéica de CTAs em nossa casuística de LH e LNH com o painel utilizado. Apesar dos limitados dados disponíveis na literatura, esses achados são concordantes com a maioria dos estudos realizados utilizando RT-PCR e/ou imunohistoquímica. Não houve correlações estatisticamente significantes entre expressão de CTAs e parâmetros clínicos ou prognósticos no presente estudo. A reatividade sérica contra os CTAs testados ocorreu em níveis semelhantes ao da expressão protéica em LNH, sugerindo que os pacientes com LNH são capazes de montar resposta imune humoral específica contra CTAs. / Cancer/testis antigens (CTAs) are expressed in a variety of malignant tumors but in normal adult tissues solely in testicular germ cells. Based on this tumor-associated expression pattern, these antigens are potential targets for immunotherapy. Though carcinomas have been extensively analyzed, less is known about lymphoid malignancies such as lymphomas. Aims: To evaluate the potential of tumor specific antigens as candidates for immunotherapy in lymphomas throughout CTA protein expression and spontaneous humoral immune response analyses. We also aim to investigate clinical correlations and prognostic impact of CTAs expression in lymphomas. Methods: Tissue microarray was generated from 38 Hodgkin´s lymphoma (HL) and 106 non- Hodgkin´s lymphoma (NHL) archival cases. Immunohistochemistry (IHC) was done using a panel of 9 monoclonal antibodies against CTAs. Spontaneous humoral immune response analysis against a larger CTA panel was performed in 97 untreated NHL patient samples, including 59 cases from the TMA cohort, using ELISA technique. Results: We found overall low expression of CTAs in our series of HL (21.1%) and NHL (11.3%) TMAs, being MAGE-A (18.4%) and CT7 (13.2%) the most frequently expressed CTAs in HL, and MAGE-A (6.6%), GAGE (5.7%), NY-ESO-1 (4.8%) and CT7 (4.8%) the most frequently expressed CTAs in NHL. Although we did not find statistically significant difference in CTA expression among the clinicopathological subgroups of HL, CTA positivity was higher in advanced stage (28.6%) compared to early stage patients (11.8%). Among NHL, we found higher CTA expression in aggressive lymphomas (14.9%) compared to indolent lymphomas (3.1%), DLBCL (16.1%) compared to non-DLBCL (6.0%) and in non-complete response group (15.0%) compared to those who achieved complete response (6.8%), but it was not statistically significant. Unexpectedly, early stage disease (19.5%) had higher CTA expression than advanced stage NHL (6.2%). Despite the difference found in survival analysis between NHL patients that presented no CTAs expression (median OS 65 months) and those who expressed at least one CTA (median OS 11 months), it did not reach statistically significant difference (p=0.0947). Serum reactivity against at least 1 CTA was observed in (19.6%) of NHL patients, being more frequent in B-cell lymphomas (21.2%) then T-cell lymphomas (6.2%) (p=0.048). CT47 was the most frequently expressed CTA (7.2%), followed by CT45 (5.1%), NY-ESO-1 (5.1%) and MAGE-A4 (5.1%). Grouping the MAGE-A family similarly to the TMA analysis, we found positivity in 8.2% of NHL serum samples. Among DLBCL, CT45 and NY-ESO-1 were the most frequently expressed CTAs, being positive in 4/50 (8.0%) and 3/50 (6.0%), respectively. Conclusion: We found overall low expression of CTAs in our series of HL and NHL TMAs, and low reactivity against CTA in our serum samples. Our results demonstrated a slightly higher frequency of humoral response against most CTAs included in both TMA and ELISA panel compared to their expression by TMA. Considering that generally a small proportion of patients expressing CTAs develop specific humoral response, it is possible that CTA expression by TMA could be underestimated due to the focal expression pattern in some patients. Therefore, using an extensive panel of antibodies and large TMA and serum cohorts of lymphoma patients, we could not identify CTA candidates for immunotherapy in HL and NHL. / TEDE / BV UNIFESP: Teses e dissertações