Analysis of the immunohistochemical expressions of p53, bcl-2 and Ki-67 in colorectal adenocarcinoma and their correlations with the prognostic factors / Análise das expressões imunoistoquímicas da p53, bcl-2 e Ki-67 no adenocarcinoma colorretal e suas correlações com os fatores prognósticos

CONTEXT: Search of tumors markers that allow treatment with higher survival rates, and indicate the response to treatment and recurrence of cancer OBJECTIVE: To analyze the immunoexpression of the proteins p53, bcl-2 and Ki-67 in colorectal adenocarcinoma and correlate them with the clinical-pathological prognostic factors. METHOD: Tissue microarray paraffin blocks were made from colorectal adenocarcinoma tissue resected from 82 patients who had undergone surgery but not chemotherapy or radiotherapy, at "Hospital São Paulo", São Paulo, SP, Brazil, between 2002 and 2005. Thin sections (4 µm) were subjected to immunohistochemical reactions, and immunoexpression staining scores were obtained. The scores were correlated with the degree of cell differentiation, staging, disease-free interval, recurrence, survival and specific mortality. The study variables were analyzed using the chi-square and Kaplan-Meier tests to investigate associations with the markers. The significance of the differences between the curves of the disease-free interval and survival was analyzed using the Logrank and Wilcoxon tests. RESULTS: The immunohistochemical expression of p53 was positive in 70 tumors (85.4 percent) and negative in 12 (14.6 percent). The expression of bcl-2 was positive in 26 (31.7 percent) and negative in 56 (68.3 percent). The expression of Ki-67 was positive in 62 (75.6 percent) and negative in 20 (24.4 percent). There was no statistically significant correlation between the expressions of these markers separately or in conjunction, in relation to the degree of cell differentiation, staging, disease-free interval, survival and specific mortality. In relation to recurrence, there was a statistically significant correlation with positive expression of Ki-67 (P = 0.035). CONCLUSION: The immunohistochemical expression of Ki-67 in colorectal cancer is associated with recurrence of this disease.

CONTEXTO: Pesquisa de marcadores tumorais que permitam tratamento com maiores índices de sobrevida, além de indicarem a resposta ao tratamento e a recurrência da neoplasia. OBJETIVO: Analisar as expressões imunoistoquímicas das proteínas p53, bcl-2 e Ki-67 no adenocarcinoma colorretal, correlacionando-as com os fatores prognósticos clínico-patológicos. MÉTODO: Foram confeccionados blocos de parafina de TMA com tecido de adenocarcinoma colorretal ressecados cirurgicamente em 82 pacientes no Hospital São Paulo da Universidade Federal der São Paulo, São Paulo, SP, de 2002 a 2005, não submetidos a radio ou quimioterapia. Cortes de 4 µm foram submetidos a reação imunoistoquímica e obtidos escores de intensidade das imunoexpressões, que foram correlacionados com o grau de diferenciação celular, estádio, tempo livre de doença, recidiva, sobrevida e mortalidade específica. As variáveis do estudo foram analisadas pelos testes do qui ao quadrado e de Kaplan-Meier para verificar as associações com os marcadores. A significância das diferenças entre as curvas do tempo livre de doença e da sobrevida foi analisada pelos testes de Logrank e Wilcoxon. RESULTADOS: A expressão imunoistoquímica da p53 foi positiva em 70 tumores (85,4 por cento) e negativa em 12 (14,6 por cento). A bcl-2 foi positiva em 26 tumores (31,7 por cento) e negativa em 56 (68,3 por cento). A expressão imunoistoquímica da Ki-67 foi positiva em 62 tumores (75,6 por cento), sendo em 20 (24,4 por cento) negativa. Não houve correlação estatisticamente significante entre as expressões imunoistoquímicas dos marcadores analisadas separadamente ou em conjunto, envolvendo o grau de diferenciação celular, estádio, tempo livre de doença, sobrevida e mortalidade específica. Com relação à recidiva, observou-se correlação estatisticamente significante com a expressão imunoistoquímica positiva da Ki-67 (P = 0,035). CONCLUSÃO: A expressão imunoistoquímica positiva da Ki-67 no câncer colorretal está...

Stimulatory heterotrimeric G protein augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 human lung cancer cells

Stimulatory heterotrimeric GTP-binding proteins (Gs protein) stimulate cAMP generation in response to various signals, and modulate various cellular phenomena such as proliferation and apoptosis. This study aimed to investigate the effect of Gs proteins on gamma ray-induced apoptosis of lung cancer cells and its molecular mechanism, as an attempt to develop a new strategy to improve the therapeutic efficacy of gamma radiation. Expression of constitutively active mutant of the alpha subunit of Gs (GalphasQL) augmented gamma ray-induced apoptosis via mitochondrial dependent pathway when assessed by clonogenic assay, FACS analysis of PI stained cells, and western blot analysis of the cytoplasmic translocation of cytochrome C and the cleavage of caspase-3 and ploy(ADP-ribose) polymerase (PARP) in H1299 human lung cancer cells. GalphasQL up-regulated the Bak expression at the levels of protein and mRNA. Treatment with inhibitors of PKA (H89), SP600125 (JNK inhibitor), and a CRE-decoy blocked GalphasQL-stimulated Bak reporter luciferase activity. Expression of GalphasQL increased basal and gamma ray-induced luciferase activity of cAMP response element binding protein (CREB) and AP-1, and the binding of CREB and AP-1 to Bak promoter. Furthermore, prostaglandin E2, a Galphas activating signal, was found to augment gamma ray-induced apoptosis, which was abolished by treatment with a prostanoid receptor antagonist. These results indicate that Galphas augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 lung cancer cells, suggesting that the efficacy of radiotherapy of lung cancer may be improved by modulating Gs signaling pathway.