The International Journal of Biochemistry & Cell Biology 39 (2007) 1305–1317 Medicine in focus Antibody arrays—An emerging tool in cancer proteomics Eliezer Kopf, Dorit Zharhary ∗ Sigma–Aldrich Israel Ltd., 3 Plaut Str., Park Rabin, Rehovot 76100, Israel Available online 13 May 2007 Abstract Cancer is a result of complex changes that occur in normal cells as they transform to become malignant and further when they become metastatic. These changes are not a consequence of a single protein but rather involve multiple proteins that function in pathways and networks. Thus, profiling cancer-associated changes requires simultaneous measurement of many proteins in a single sample. Identifying these changes may lead to the discovery of cancer-associated biomarkers that may assist in diagnosis, prognosis, patient monitoring and possibly for therapeutic purposes. Antibody arrays are a relatively new technology that enables one to perform multiplex high-throughput protein expression profiling. This review describes current technologies in antibody array and assay design, and presents a survey of the current literature on the use of these arrays in cancer research. © 2007 Elsevier Ltd. All rights reserved. Keywords: Antibody array; Proteomics; Protein profiling; Biomarkers; Cancer 1. Introduction Cancer is associated with changes in cellular protein expression that lead to alteration in signaling pathways and oncogenesis. These changes often induce changes in the tumor microenvironment, cause inflammation and result in changes in the profile of secreted proteins to the blood. Assessing the changes in cellular protein expres- sion and identifying disease relevant proteins can provide information about the physiological status of the organ- ism. The main goal in cancer proteomics is to identify a disease specific protein biomarker or more complex “protein signatures” that are associated with a specific malignancy or a specific stage of malignancy. The hope is that these signatures can then be used for better diagno- Abbreviations: CD, cluster of differentiation; ELISA, enzyme linked immunosorbent assay; PSA, prostate specific antigen; RTK, receptor tyrosine kinase; STAT, signal transducer and activator of tran- scription; SPR, surface plasmon resonance; TIF, tumor interstitial fluid ∗ Corresponding author. Tel.: +972 8 9484145; fax: +972 8 9484323. E-mail address: dzharhar@europe.sial.com (D. Zharhary). sis and prognosis, for predicting disease progression, for predicting response or resistance to therapy, and possibly for identifying drug targets. For the last decade, DNA arrays have been success- fully used for gene expression profiling of cells at the mRNA level. However, DNA arrays have certain lim- itations: since there is not always a direct correlation between mRNA levels and protein expression (Gygi, Rochon, Franza, & Aebersold, 1999) gene expression profiling may not represent the actual cellular proteome. Moreover, post-translational modifications, which can- not be detected at the mRNA level, may play an important role in oncogenesis. In addition, profiling gene expres- sion requires that the assayed sample be extracted from an intact cell that has mRNA, and thus the use of body flu- ids that contain mainly secreted proteins is limited. Using body fluids, and especially plasma or urine, as the clini- cal sample is most convenient and the least invasive way for disease diagnosis. Antibody arrays, which are a rela- tively new technology, are used to profile directly protein expression and thus provide more meaningful results. They enable the researcher to profile hundreds and ulti- 1357-2725/$ – see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biocel.2007.04.029