Palladin Is a Novel Marker of Metastasis in Primary Pancreatic Endocrine Neoplasms
EB Henderson-Jackson, L Turner, N Hafez, NA Nasir, J Strosberg, J Helm, D Agrawal, MM Bui, D Coppola, SV Nicosia, L Kvols, MP Malafa, A Nasir. H Lee Moffitt Cancer Center and Research Institute, Tampa, FL; University of South Florida College of Medicine, Tampa, FL
Background: Based on gene expression profiling we identified a number of novel metastasis-associated genes in primary PECAs (MP-PECAs) with liver metastases as compared to clinically localized primary PETs (CLP-PETs). One of the top genes, palladin, is intimately involved in cell structure and motility. The purpose of this analysis was to validate the expression of palladin in pancreatic endocrine neoplasms at protein level and to determine its association with the presence of liver metastasis.
Design: A pancreatic endocrine tumor tissue microarray (TMA) was constructed using well-differentiated pancreatic endocrine tumors/carcinomas (PETs/PECAs) and non-neoplastic pancreatic tissue/islets. The TMA was immunostained with rabbit anti-human Palladin polyclonal antibody (dilution 1:50) (ProteinTech Inc. Chicago IL). The staining results were expressed as low or high expression based on the intensity and distribution of staining and was correlated with presence or absence of liver metastases.
Results: Our study included 24 males and 32 females, age range: 17 to 79 (mean age 54), with tumor size ranging from 0.6 cm to 11.5 cm (mean 3.0 cm). All tumors were well-differentiated PETs/PECAs (WHO 2004). Palladin staining was cytoplasmic. High palladin expression was found in 73% of PECAs but in only 21% of PETs. Conversely, low palladin expression was seen in 11% of PETs but in only 3% of PECAs. Histologically normal pancreatic islets were negative or showed weak palladin expression [Table1]. High expression of palladin was associated with liver metastasis (p = 0.017).
Expression of Palladin in PECAs/PETs
|H-score||Intensity of Palladin Staining||Primary PETs with no liver metastases (CLP-PETs) no. cases (%)||Primary PECAs with liver metastases (MP-PECAs) no. cases (%)|
|Low expression||1||11 (79)||3 (27)|
|High expression||>1||3 (21)||8 (73)|
Conclusions: Palladin appears to be a promising marker of metastatic potential in primary pancreatic endocrine neoplasms. The over-expression of this protein in primary endocrine tumors suggests that cytoskeletal abnormalities may contribute to the invasiveness and metastatic phenotype in these neoplasms.
Monday, March 9, 2009 9:30 AM
Poster Session I Stowell-Orbison/Autopsy Award # 85, Monday Morning