Actinin-4 Expression in Primary and Metastasized Pancreatic Ductal Adenocarcinoma

Objectives: Actinin-4 is an actin-bundling protein that probably has a tumor-promoting potential in several solid tumors. The present study analyzed the expression of actinin-4 in the pancreas, in localized and metastasized pancreatic ductal adenocarcinoma (PDAC), and the correlation with clinical outcome. Methods: Pancreatic ductal adenocarcinoma tissue from 38 patients, 15 lymph node and 10 liver metastases, normal pancreas, and 4 PDAC cell lines, were examined by immunohistochemistry, and actinin-4 expression was quantified by immunofluorescence analysis. Results: In the normal pancreas, actinin-4 was most prominently expressed in ductal cells. In PDAC, tumor cells exhibited strong but differential cytoplasmic immunoreactivity for actinin-4. A multivariate analysis revealed actinin-4 immunoreactivity, advanced age, and undifferentiated grade as significant prognostic factors associated with worse survival after PDAC resection. Cells metastasized to lymph nodes or to the liver exhibited no significant increase of actinin-4 compared with the primary tumors. A nuclear staining was observed neither in any of the PDAC samples nor in the 4 cell lines. In PDAC cells, actinin-4 localized to dynamic actin structures and to invadopodia. Conclusions: Actinin-4 expression levels significantly correlate with worse survival after PDAC resection. Although actinin-4 has been reported to promote lymph node metastases, there was no enhanced expression in PDAC metastases.