Assessment of the clinical significance of antigenic and functional levels of α1-proteinase inhibitor (α1-Pi) in infiltrating ductal breast carcinomas Amel ben Anes a, 1 , Hela ben Nasr b, 1 , Philippe Hammann c , Lauriane Kuhn c , Mounir Trimeche d , Bechr Hamrita e , Iheb Bougmiza f , Anouar Chaieb g , Hedi Khairi g , Karim Chahed a, h, ⁎ a Laboratoire d'Immuno-Oncologie Moléculaire, Faculté de Médecine de Monastir, Tunisia b Unité de recherche, adaptations cardio-circulatoires et hormonales à l'exercice musculaire, Faculté de Medecine, Sousse, Tunisia c Plate Forme Protéomique, Institut de Biologie Moléculaire et Cellulaire, CNRS, 67084 Strasbourg, France d Département de Pathologie, CHU Farhat Hached, Sousse, Tunisia e Institut Préparatoire des écoles d'Ingénieurs, Sfax, Tunisia f Département de Médecine Communautaire, Faculté de Médecine de Sousse, Tunisia g Service d'obstétrique et des maladies féminines, Centre Hospitalo-Universitaire-Farhat-Hached, Sousse, Tunisia h Faculté des Sciences de Sfax, Département de Biochimie, Université de Sfax, Tunisia abstract article info Article history: Received 3 February 2012 Received in revised form 28 May 2012 Accepted 15 July 2012 Available online 26 July 2012 Keywords: Breast cancer α1-proteinase inhibitor Metastasis Proteomics Objectives: To determine the clinical significance of α1-proteinase inhibitor (α1-Pi) in infiltrating ductal breast carcinoma patients. Design and methods: Serum levels of α1-Pi, tryptic specific inhibitory capacity and α1-Pi circulating im- mune complexes were determined using radial immunodiffusion, BAPNA assays and ELISA, respectively. 2-DE-MS and immunohistochemistry were performed to examine α1-Pi protein expression. Results: A decreased serum level of α1-Pi was found among breast cancer patients in comparison to con- trols. In addition, we found a significantly decreased mean level of α1-Pi in the node metastatic group when compared to node negative patients. However, the functional activity of the inhibitor did not decrease pro- portionately. Through 2-DE analyses, a differential expression of α1-Pi isoforms according to tumor stage and node metastatic development was found. Conclusions: Both α1-Pi levels and specific activity could be a source of complementary clinical informa- tion and may provide useful information for a better understanding of the mechanisms of metastasis. © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. 1. Introduction Tumor cells are characterized by their ability to invade normal tis- sues and to spread. This invasion is in part due to proteases, which are suspected to play a major role in extracellular matrix proteolysis and cell migration. While under normal physiological conditions a balance exists between proteases and their inhibitors, recent findings suggest that an imbalance between these two counterpart proteins may arise as either a causative or a responsive element in malignant diseases and could be related to tissue damage and disease progression [1]. Up to now, although increasing evidence suggests that proteolytic en- zymes play crucial roles in cell proliferation and spread of cancer, the role of the body's natural inhibitors of these enzymes in such process- es remains largely unknown. The α1-proteinase inhibitor (α1-Pi), also known as serpin A1 is among the protease inhibitors whose main function is to inhibit leukocyte elastase, trypsin and plasminogen [2]. This proteinase in- hibitor has also been shown to block TGF-alpha release from its membrane-bound precursor on MCF-7 breast cancer cells, which may affect anchorage dependent growth thus acting as a tumor sup- pressor [3]. It was also found to stimulate fibroblast proliferation and procollagen synthesis and interact with enzymes involved in ap- optosis [4, 5]. Additionally, native α1-Pi has been shown to increase insulin-induced mitogenesis, to inhibit cell growth in human plasma and decrease tendency towards metastasis [6]. α1-Pi is synthesized essentially in the liver but also in alveolar macrophages, circulating monocytes and in tumor cells [7]. This protein plays a crucial role in many processes and was found to be increased above normal values during the acute phase response and in chronic diseases such as in liver cirrhosis and hepatitis [8]. Up to now, several studies have re- vealed that serum levels of α1-Pi are significantly elevated in neo- plastic diseases and may correlate with tumor progression [9]. In contrast, others have reported a significant correlation between α1-Pi down-regulation and increased risk of different types of cancer and may thus play a protective role in tumorogenesis [3]. Clinical Biochemistry 45 (2012) 1421–1431 ⁎ Corresponding author at: Laboratoire d'Immuno-Oncologie Moléculaire, Faculté de Médecine de Monastir, Tunisia. E-mail address: k.chahed@yahoo.fr (K. Chahed). 1 Amel ben Anes and Hela ben Nasr are co-first authors and contributed equally to the study. 0009-9120/$ – see front matter © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.clinbiochem.2012.07.099 Contents lists available at SciVerse ScienceDirect Clinical Biochemistry journal homepage: www.elsevier.com/locate/clinbiochem