RESEARCH ARTICLE The expression of S100A8 in pancreatic cancer- associated monocytes is associated with the Smad4 status of pancreatic cancer cells Adnan A. Sheikh 1 * , Dale Vimalachandran 1 * , Christopher C. Thompson 1 , Rosalind E. Jenkins 2 , Taoufik Nedjadi 1 , Ali Shekouh 1 , Fiona Campbell 3 , Andrew Dodson 3 , Wendy Prime 4 , Tatjana Crnogorac-Jurcevic 5 , Nicholas R. Lemoine 5 and Eithne Costello 1 1 Division of Surgery and Oncology, Royal Liverpool University Hospital, University of Liverpool, Liverpool, UK 2 Biomedical Sciences Proteomics Facility, Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK 3 Department of Pathology, University of Liverpool, Liverpool, UK 4 Cancer Tissue Bank Research Centre, Department of Pathology, University of Liverpool, Liverpool, UK 5 Cancer Research UK Centre for Molecular Oncology Unit, Institute of Cancer, Barts, and the London School of Medicine and Dentistry, London, UK The cross-talk between tumour cells and the surrounding supporting host cells (stroma) is a key regulator of cancer growth and progression. By undertaking 2-DE analysis of laser capture microdissected malignant and stromal components of pancreatic tumours and benign ductal elements, we have identified high levels of S100A8 and S100A9 in tumour-associated stroma but not in benign or malignant epithelia. Immunohistochemical analysis (n = 71 patients) revealed strong expression of both proteins in stromal myeloid cells, subsequently identified as CD14 1 / CD68 - monocytes/macrophages. Co-immunofluorescence revealed that S100A8 was expressed in a subset of S100A9-positive cells. Correlation of the expression of S100A8 and S100A9 to patient parameters revealed that the microenvironments of tumours which lacked expression of the tumour suppressor protein, Smad4, had significantly reduced numbers of S100A8-immuno- reactive (p = 0.023) but not S100A9-immunoreactive (p = 0.21) cells. The ratio of S100A8- to S100A9-positive cells within individual tumours was significantly lower in Smad4-negative tumours than in Smad4-positive tumours (p,0.003). Pancreatitic specimens also contained S100A8- and S100A9-expressing cells, although this was not observed in regions displaying extensive fibrosis. In conclusion, our study provides an extensive analysis of S100A8 and S100A9 in pancreatic disease and highlights a potentially important relationship between pancreatic cancer cells and their surrounding microenvironment. Received: December 1, 2006 Revised: January 25, 2007 Accepted: February 24 2007 Keywords: Monocytes / Pancreatic cancer / S100A8 / S100A9 / Smad4 Proteomics 2007, 7, 1929–1940 1929 1 Introduction Pancreatic cancer is one of the most aggressive human can- cers. Globally it is one of the leading causes of cancer-related deaths, accounting for over 200 000 deaths in the year 2000 alone [1]. A characteristic genetic signature has been eluci- Correspondence: Dr. Eithne Costello, Division of Surgery and Oncology, Royal Liverpool University Hospital, 5th Floor UCD Building, Daulby Street, Liverpool, UK E-mail: ecostell@liv.ac.uk Fax: 144-151-706-5826 Abbreviations: IQR, inter-quartile range; TGF-â, transforming growth factor-beta; TMA, tissue microarrays * These authors contributed equally to this work. DOI 10.1002/pmic.200700072  2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.proteomics-journal.com