Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 12 2 2013 06 15 161 167 EN Nastaran Alizadeh Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mohammad Mehdi Amiri Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Alireza Salek Moghadam Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Amir Hassan Zarnani Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Farshid Saadat Department of Immunology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran Farnaz Safavifar Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Research Institute, Tehran University of Medical Sciences, Tehran, Iran Azar Berahmeh Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Research Institute, Tehran University of Medical Sciences, Tehran, Iran Mohammad Reza Khorramizadeh Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Research Institute, Tehran University of Medical Sciences, Tehran, Iran AND Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran AND Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran 2015 10 16 There exists compelling evidence that Toll-like receptor 3 (TLR3) agonists can directly affect human cancer cells. The aim of this study was to investigate anti-cancer effects of TLR3 agonist in human breast cell line. We assessed potential effects of poly (A:U) on human breast cell line (MDA-MB-231)  on a dose-response and time-course  basis. Human breast cell line  MDA-MB-231  was treated with different concentrations of poly (A:U) and lipopolysaccharide  (LPS). Then, the following assays were performed on the treated cells: dose-response  and time-course cytotoxicity using colorimetric method; matrix metalloproteinase-2  (MMP-2) activity using gelatin zymography method; apoptosis using annexin-v flowcytometry method; and relative expression of TLR3 and MMP-2 mRNA using reverse transcriptase  polymerase chain reaction (RT-PCR) method. Following treatments, dose- response and time-course cytotoxicity using a colorimetric method, (MMP-2) activity (using gelatin zymography), apoptosis  (using annexin-v flowcytometry method) assays and expression of TLR3 and MMP-2 genes (using PCR method) were performed. Cytotoxicity and flowcytometry analysis of poly (A:U) showed that poly (A:U) do not have any cytotoxic and apoptotic effects in different concentrations used. MMP-2 activity analysis showed significant decrease in higher concentrations  (50 and 100 µg/ ml) between treated and untreated cells.  Moreover, poly A:U treated cells demonstrated decreased expression of MMP-2 gene in higher concentrations. Collectively, our data indicated that human breast cancer cell line (MDA-MB-231) was highly responsive to poly (A:U). The antimetastatic effect of direct poly (A:U) and TLR3 interactions in MDA-MB-231 cells could provide new approaches in malignant tumor therapeutic strategy. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/518 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/518/514