Cholesterol-enriched membrane microdomains are needed for insulin signaling and proliferation in hepatic cells.

Hepatocyte proliferation during liver regeneration is a well-coordinated process regulated by the activation of several growth factor receptors, including the insulin receptor (IR). The IR can be localized in part to cholesterol-enriched membrane microdomains, but the role of such domains in insulin-mediated events in hepatocytes is not known. We investigated whether partitioning of IRs into cholesterol-enriched membrane rafts is important for the mitogenic effects of insulin in the hepatic cells. IR and lipid rafts were labeled in HepG2 cells and primary rat hepatocytes. Membrane cholesterol was depleted in vitro with metyl-ß-cyclodextrin (MßCD) and in vivo with lovastatin. Insulin-induced calcium (Ca2+) signals studies were examined in HepG2 cells and in freshly isolated rat hepatocytes as well as in whole liver in vivo by intravital confocal imaging. Liver regeneration was studied by 70% partial hepatectomy (PH), and hepatocyte proliferation was assessed by PCNA staining. A subpopulation of IR was found in membrane microdomains enriched in cholesterol. Depletion of cholesterol from plasma membrane resulted in redistribution of the IR along the cells, which was associated with impaired insulin-induced nuclear Ca2+ signals, a signaling event that regulates hepatocyte proliferation. Cholesterol depletion also led to ERK1/2 hyper-phosphorylation. Lovastatin administration to rats decreased hepatic cholesterol content, disrupted lipid rafts and decreased insulin-induced Ca2+ signaling in hepatocytes, and delayed liver regeneration after PH. Therefore, membrane cholesterol content and lipid rafts integrity showed to be important for the proliferative effects of insulin in hepatic cells. NEW & NOTEWORTHY One of insulin's actions is to stimulate liver regeneration. Here we show that a subpopulation of insulin receptors is in a specialized cholesterol-enriched region of the cell membrane and this subfraction is important for insulin's proliferative effects.

Expression of epidermal growth factor receptor (EGFR) in cholangiocarcinomas: predictive factors and survival.

OBJECTIVE: to evaluate the expression of the epithelial growth factor receptor (EGFR) by immunohistochemistry, and to verify its association with prognostic factors and survival of patients operated by cholangiocarcinoma. METHODS: we verified the immunohistochemical expression of EGFR in 35 surgical specimens of cholangiocarcinoma (CCA). We obtained survival curves with the Kaplan-Meier method. RESULTS: we found significant EGFR expression in ten (28.6%) of the 35 CCAs, eight with score 3 and two with score 2. Advanced stages (III and IV) presented higher EGFR expression (p=0.07). The clinical characteristics that were most associated with positive EGFR expression were female gender (p=0.06) and absence of comorbidities (p=0.06). Overall survival at 12, 24, 36 and 48 months was 100%, 82.5%, 59% and 44.2%, respectively. The survival of EGFR positive patients at 12, 24, 36 and 48 months was 100%, 75%, 50% and 0%, whereas for negative EGFR patients it was 100%, 87.5%, 65.6% and 65.6%, respectively. CONCLUSION: EGFR expression occurred in 28.6% of the cases studied and was associated with lower survival.

Immunohistochemical Predictors for Intestinal and Pancreatobiliary Types of Adenocarcinoma of The Ampulla of Vater.

OBJECTIVES: To investigate immunohistochemical predictors for intestinal and pancreatobiliary types of adenocarcinoma of ampulla of Vater and identify clinicopathological characteristics associated with the histological types and patient survival. METHODS: Immunohistochemical markers included MUC1, MUC2, MUC5AC, CDX2, CK7, and CK20. The data were analyzed by univariate and multivariate methods. The two-step cluster method was used to determine the best immunohistochemical markers to discriminate the intestinal from the pancreatobiliary type. RESULTS: This study identified 9 (33.3%) intestinal and 21 (66.7%) pancreatobiliary tumors. CK7 and CDX2 achieved the highest value (= 1) as predictor markers, while CK20, MUC1, and MUC2 showed degrees of importance equal to 0.77, 0.71, and 0.68, respectively. MUC5AC did not reach 0.50 of importance. In the univariate analysis, lymph node involvement, staging (TNM), and angiolymphatic and perineural invasions were associated with histological types. The independent clinicopathological variable in the multivariate model to predict the histological type was angiolymphatic invasion (p = 0.005), OR = 17 (95% CI 2.33 to 123.83). The final model showed positive nodes (N1) associated with shorter survival (HR = 9.5; p = 0.006). Overall survival at 12, 36, and 60 months was 88.5, 67.0, and 47.6%, respectively. CONCLUSIONS: CDX2 and CK7 were the immunohistochemical markers that best discriminated the intestinal from the pancreatobiliary type. Lymph node involvement had a high impact on survival and proved to be more frequent in the pancreatobiliary type.

Expression of epidermal growth factor receptor (EGFR) in cholangiocarcinomas: predictive factors and survival / Expressão do receptor do fator de crescimento epitelial (EGFR) em colangiocarcinomas: fatores preditivos e sobrevida

ABSTRACT Objective: to evaluate the expression of the epithelial growth factor receptor (EGFR) by immunohistochemistry, and to verify its association with prognostic factors and survival of patients operated by cholangiocarcinoma. Methods: we verified the immunohistochemical expression of EGFR in 35 surgical specimens of cholangiocarcinoma (CCA). We obtained survival curves with the Kaplan-Meier method. Results: we found significant EGFR expression in ten (28.6%) of the 35 CCAs, eight with score 3 and two with score 2. Advanced stages (III and IV) presented higher EGFR expression (p=0.07). The clinical characteristics that were most associated with positive EGFR expression were female gender (p=0.06) and absence of comorbidities (p=0.06). Overall survival at 12, 24, 36 and 48 months was 100%, 82.5%, 59% and 44.2%, respectively. The survival of EGFR positive patients at 12, 24, 36 and 48 months was 100%, 75%, 50% and 0%, whereas for negative EGFR patients it was 100%, 87.5%, 65.6% and 65.6%, respectively. Conclusion: EGFR expression occurred in 28.6% of the cases studied and was associated with lower survival.

RESUMO Objetivo: avaliar a expressão do receptor do fator de crescimento epitelial (EGFR) por meio de imuno-histoquímica, e verificar sua associação com fatores prognósticos e com a sobrevida dos pacientes operados por colangiocarcinoma. Métodos: a expressão imuno-histoquímica de EGFR foi verificada em 35 peças cirúrgicas de colangiocarcinomas (CCA). Curvas de sobrevida foram obtidas pelo método de Kaplan-Meier. Resultados: expressão significativa de EGFR foi encontrada em dez (28,6%) de 35 CCA, oito com escore 3 e dois com escore 2. Estágios avançados (III e IV) apresentaram maior expressão de EGFR (p=0,07). As características clínicas que mais estiveram associadas com a expressão positiva de EGFR foram o sexo feminino (p=0,06) e ausência de comorbidades (p=0,06). A sobrevida global aos 12, 24, 36 e 48 meses foi de 100%, 82,5%, 59% e 44,2%, respectivamente. A sobrevida de pacientes EGFR positivos aos 12, 24, 36 e 48 meses foi de 100%, 75%, 50% e 0%, enquanto que para EGFR negativos foi de 100%, 87,5%, 65,6% e 65,6%, respectivamente. Conclusão: a expressão do EGFR ocorreu em 28,6% dos casos estudados e esteve associada a menor sobrevida.