Isoform-specific upregulation of palladin in human and murine pancreas tumors

• Published in: PloS one Vol. 5; no. 4; p. e10347
• Main Authors: Goicoechea, Silvia M, Bednarski, Brian, Stack, Christianna, Cowan, David W, Volmar, Keith, Thorne, Leigh, Cukierman, Edna, Rustgi, Anil K, Brentnall, Teresa, Hwang, Rosa F, McCulloch, Christopher A G, Yeh, Jen Jen, Bentrem, David J, Hochwald, Steven N, Hingorani, Sunil R, Kim, Hong Jin, Otey, Carol A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.04.2010; Public Library of Science (PLoS)
• Subjects: Actin; Adenocarcinoma; Analysis; Animals; Biomarkers; Biomarkers, Tumor; Cancer diagnosis; Cancer metastasis; Carcinoma, Pancreatic Ductal - diagnosis; Cell Biology/Cytoskeleton; Cytoskeletal Proteins - analysis; Cytoskeletal Proteins - genetics; Cytoskeleton; Epidemiology; Epithelial cells; Extracellular matrix; Fibroblasts; Fibroblasts - pathology; Gastroenterology and Hepatology/Gastrointestinal Cancers; Gastroenterology and Hepatology/Pancreas; Genetic engineering; Genetically modified organisms; Growth factors; Humans; Immunoassay; Immunohistochemistry; Isoforms; Laboratories; Medicine; Metastases; Metastasis; Mice; Monoclonal antibodies; Morphogenesis; Motility; Muscle proteins; Mutation; Neoplasm Proteins; Oncology; Oncology/Gastrointestinal Cancers; Pancreas; Pancreatic cancer; Phosphoproteins - analysis; Phosphoproteins - genetics; Physiology; Protein Isoforms; Proteins; Reverse Transcriptase Polymerase Chain Reaction; Reverse transcription; RNA, Messenger - analysis; Surgery; Tumors; Up-Regulation; North Carolina; United States > US; Pennsylvania
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0010347

Pancreatic ductal adenocarcinoma (PDA) is a lethal disease with a characteristic pattern of early metastasis, which is driving a search for biomarkers that can be used to detect the cancer at an early stage. Recently, the actin-associated protein palladin was identified as a candidate biomarker when it was shown that palladin is mutated in a rare inherited form of PDA, and overexpressed in many sporadic pancreas tumors and premalignant precursors. In this study, we analyzed the expression of palladin isoforms in murine and human PDA and explored palladin's potential use in diagnosing PDA. We performed immunohistochemistry and immunoblot analyses on patient samples and tumor-derived cells using an isoform-selective monoclonal antibody and a pan-palladin polyclonal antibody. Immunoblot and real-time quantitative reverse transcription-PCR were used to quantify palladin mRNA levels in human samples. We show that there are two major palladin isoforms expressed in pancreas: 65 and 85-90 kDa. The 65 kDa isoform is expressed in both normal and neoplastic ductal epithelial cells. The 85-90 kDa palladin isoform is highly overexpressed in tumor-associated fibroblasts (TAFs) in both primary and metastatic tumors compared to normal pancreas, in samples obtained from either human patients or genetically engineered mice. In tumor-derived cultured cells, expression of palladin isoforms follows cell-type specific patterns, with the 85-90 kDa isoform in TAFs, and the 65 kDa isoform predominating in normal and neoplastic epithelial cells. These results suggest that upregulation of 85-90 kDa palladin isoform may play a role in the establishment of the TAF phenotype, and thus in the formation of a desmoplastic tumor microenvironment. Thus, palladin may have a potential use in the early diagnosis of PDA and may have much broader significance in understanding metastatic behavior.