Pesquisa de alvos terapêuticos em carcinomas de células escamosas de cão: EGFR; Cox-2; KI-67
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2016-06-29
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O carcinoma de células escamosas (CCE) é uma neoplasia maligna da pele que tem a sua origem no crescimento descontrolado de células das camadas superiores da epiderme. Sendo a segunda neoplasia cutânea mais comum em cães, acredita-se que as radiações UV sejam o principal fator para o desenvolvimento desta doença, surgindo na maioria dos casos em zonas com pouco pelo e/ou com pouca ou nenhuma pigmentação.
Neste estudo procedeu-se à avaliação da expressão de 3 marcadores associados a neoplasias: Epidermal Growth Factor (EGFR), Ciclooxigenase-2 (Cox-2) e Ki-67 com o objetivo de averiguar potenciais alvos terapêuticos.
Neste estudo foram analisados 37 casos de CCE. As amostras foram classificadas a partir das variáveis clínicas, as características histológicas e o grau histológico de malignidade.
A imunorreatividade dos marcadores Ki-67, Cox-2 e EGFR foi determinada através de métodos imunohistoquímicos.
A expressão do Ki-67 foi avaliada através de método quantitativo, tendo-se selecionado hotspots com maior positividade e homogeneidade de marcação considerando-se imunorreativas quando a marcação ocorria no núcleo, independentemente da sua intensidade. Os resultados deste anticorpo foram classificados em 2 grupos (baixo e elevado) com base na média dos valores de positividade.
A expressão da Cox-2 foi considerada positiva quando se observou uma coloração acastanhada no citoplasma das células. A percentagem de células positivas foi avaliada semiquantitativamente em 4 grupos para a extensão e 3 grupos quanto à intensidade de marcação.
A avaliação da expressão do EGFR foi efetuada semiquantitativamente, tendo sido considerada a existência de imunorreatividade quando foi observada uma marcação acastanhada no citoplasma e na membrana citoplasmática das células, tendo sido contabilizada a marcação membranar quando esta era mais intensa que a marcação citoplasmática. A intensidade foi avaliada em 3 graus considerando-se sobre-expressão da marcação nos casos e intensidade de grau 3.
Ocorreu sobre-expressão da marcação de EGFR em 43,2% dos casos, tendo esta relevância estatística quando associada à presença de êmbolos (p = 0.001) e ao grau histológico de malignidade (p = 0.004).
A marcação da Cox-2 ocorreu em 97,3% dos casos, tendo sido a maioria classificada em grau 3 de intensidade e em grau 4 de extensão. Não existe relevância estatística entre a imunorreatividade e os parâmetros histológicos, tanto para a extensão, como para a intensidade (p > 0.05).
Observou-se elevada marcação pelo Ki-67 em 56,8% dos casos, não existindo significância entre a imunorreatividade e os parâmetros histopatológicos (p > 0.05) à exceção da relação com o grau histológico de malignidade (p = 0.040).
A associação entre a expressão imunohistoquímica dos diferentes marcadores revelou que apenas existe relevância entre a expressão do EGFR e as classes de marcação do Ki-67 (p = 0.006).
Com este estudo, demonstrou-se que existem relações estatisticamente relevantes entre estes marcadores e a malignidade dos tumores. A presença do EGFR, da Cox-2 e do KI-67 em neoplasias e atendendo à sua influência na progressão da doença, revela que estes podem ser potenciais alvos terapêuticos. Para além disso, ficou demonstrada a relação entre a marcação do EGFR e a marcação do KI-67 podendo estes marcadores ser utilizados futuramente na deteção de células tumorais proliferativas.
Squamous cell carcinoma (SCC) is a malignant neoplasm of the skin that originates from uncontrolled cell growth of the upper layers of the epidermis. As the second most common skin cancer in dogs, it is believed that UV radiation is the main factor for the development of this disease, which appears in most cases in areas with lack of fur and lightly or unpigmented areas. In this study we evaluated the expression of 3 markers associated with cancer: Epidermal growth factor receptor (EGFR), cyclooxygenase-2 (Cox-2) and Ki-67 in order to determine their eventual value as potential therapeutic targets. In this study, 37 cases of CCE were analyzed. Samples were classified accordingly to the clinical and histological features and the histological grade of malignancy. The immunoreactivity for Ki-67, Cox-2 and EGFR were determined by means of immunohistochemical methods. The Ki-67 expression was assessed by quantitative method, having been selected the most positive hotspots and marking homogeneity considering immunoreactive when staining occurred in the nucleus, regardless of their intensity. The results of this antibody were classified into 2 groups (low and high) based on the average of positive values. Expression of Cox-2 was considered positive if a brownish staining was observed in the cytoplasm of the cells. The percentage of positive cells was evaluated semiquantitatively in four groups concerning extent and 3 groups regarding the intensity of labeling. The assessment of EGFR expression was done semiquantitatively, having been considered the presence of immunoreactivity when a brownish staining was observed in the cytoplasm and the cytoplasmic membrane of the cells. The membrane labeling was recorded when it was more intense then the citoplasmatic labeling. The intensity was evaluated in 3 grades and over expression was considered in cases with intensity level 3. EGFR Overexpression occurred in 43.2% of cases, and it is statistically significant when associated with the presence of emboli (p = 0.001) and histological grade of malignancy (p = 0.004). Cox-2 labeling occurred in 97.3% of cases being the majority of this cases classified as intensity grade 3 and extension grade 4. No statistical significance was detected between immunoreactivity and histological parameters, both for the extension and intensity (p > 0.05). There was a high labeling for Ki-67 in 56.8% of cases, with no statistical relation between the immunoreactivity and histopathological parameters (p > 0.05) except for the association with the histological grade of malignancy (p = 0.040). The association between the immunohistochemical expression of the different markers, revealed that significance only exists between the expression of EGFR and Ki-67 labeling class (p = 0.006). With this study, it was demonstrated that there is a statistically significant relationship between these markers and malignant tumors. The presence of EGFR, Cox-2 and Ki-67 in cancer and in view of its influence on the progression of the disease, shows that they may be potential therapeutic targets. In addition, the relationship demonstrated between the labeling of EGFR and Ki-67 may be used in the future in the detection of proliferating tumor cells.
Squamous cell carcinoma (SCC) is a malignant neoplasm of the skin that originates from uncontrolled cell growth of the upper layers of the epidermis. As the second most common skin cancer in dogs, it is believed that UV radiation is the main factor for the development of this disease, which appears in most cases in areas with lack of fur and lightly or unpigmented areas. In this study we evaluated the expression of 3 markers associated with cancer: Epidermal growth factor receptor (EGFR), cyclooxygenase-2 (Cox-2) and Ki-67 in order to determine their eventual value as potential therapeutic targets. In this study, 37 cases of CCE were analyzed. Samples were classified accordingly to the clinical and histological features and the histological grade of malignancy. The immunoreactivity for Ki-67, Cox-2 and EGFR were determined by means of immunohistochemical methods. The Ki-67 expression was assessed by quantitative method, having been selected the most positive hotspots and marking homogeneity considering immunoreactive when staining occurred in the nucleus, regardless of their intensity. The results of this antibody were classified into 2 groups (low and high) based on the average of positive values. Expression of Cox-2 was considered positive if a brownish staining was observed in the cytoplasm of the cells. The percentage of positive cells was evaluated semiquantitatively in four groups concerning extent and 3 groups regarding the intensity of labeling. The assessment of EGFR expression was done semiquantitatively, having been considered the presence of immunoreactivity when a brownish staining was observed in the cytoplasm and the cytoplasmic membrane of the cells. The membrane labeling was recorded when it was more intense then the citoplasmatic labeling. The intensity was evaluated in 3 grades and over expression was considered in cases with intensity level 3. EGFR Overexpression occurred in 43.2% of cases, and it is statistically significant when associated with the presence of emboli (p = 0.001) and histological grade of malignancy (p = 0.004). Cox-2 labeling occurred in 97.3% of cases being the majority of this cases classified as intensity grade 3 and extension grade 4. No statistical significance was detected between immunoreactivity and histological parameters, both for the extension and intensity (p > 0.05). There was a high labeling for Ki-67 in 56.8% of cases, with no statistical relation between the immunoreactivity and histopathological parameters (p > 0.05) except for the association with the histological grade of malignancy (p = 0.040). The association between the immunohistochemical expression of the different markers, revealed that significance only exists between the expression of EGFR and Ki-67 labeling class (p = 0.006). With this study, it was demonstrated that there is a statistically significant relationship between these markers and malignant tumors. The presence of EGFR, Cox-2 and Ki-67 in cancer and in view of its influence on the progression of the disease, shows that they may be potential therapeutic targets. In addition, the relationship demonstrated between the labeling of EGFR and Ki-67 may be used in the future in the detection of proliferating tumor cells.
Descrição
Dissertação de Mestrado em Genética Molecular Comparativa e Tecnológica
Palavras-chave
Carcinoma de células escamosas , Biomarcadores tumorais , Terapêutica , Cão