Tehran University of Medical Sciences Basic & Clinical Cancer Research 2228-6527 12 2 2021 01 03 81 90 Zahra Zare Department of Biology, Farhangian University, Tehran, Iran. Tina Nayerpour Dizaj Department of Medical Biotechnology, Faculty of Modern Sciences, Tabriz University of Medical Sciences, Tabriz, Iran. Armaghan Lohrasbi Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA, UK. AND Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran. Zakieh Sadat Sheikhalishahi Department of Physiology, Shahid Sadoghi University of Medical Sciences, Yazd, Iran. Amirhooman Asadi Veterinary Medicine, Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Karaj, Iran. Mana Zakeri Department of Biology, Tehran Medical Branch, Islamic Azad University, Tehran, Iran. Fahimeh Hosseinabadi Biology Department, Faculty of Sciences, Arak University, Arak, Iran. Omid Abazari Department of Clinical Biochemistry, school of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Mojtaba Abbasi Faculty of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran. AND Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran Parisa Khanicheragh Department of Clinical Biochemistry, Lorestan University of Medical Sciences, Khorramabad, Iran. 2020 06 10 2020 12 29 Background: Metastasis of cancer cells is the primary responsible for death in patients with colorectal cancer (CRC). Transforming growth factor-β (TGF-β)-induced matrix metalloproteinases (MMPs) are essential for the metastasis process. Silibinin is a natural compound extracted from the Silybum marianum that exhibits anti-neoplastic activity in cancer cell lines. In this study, we evaluated the effects of silibinin on MMP-2 and MMP-9 induced by TGF-β in human HT-29 CRC cell line and the potential mechanism underlying the effects. Methods: The present in vitro study was done on the HT-29 cell line. The HT-29 cell line was cultured in RPMI1640 and exposed to TGF- β (5 ng/ml) in the absence and presence of different concentrations of silibinin (10, 25, 50, and 100 μM). The effect of silibinin on HT-29 cell viability was measured with the MTT assay. A real-time polymerase chain reaction (Real-Time PCR) determined the relative mRNA expression of MMP-2 and MMP-9. Western blotting was employed to examine MMP-2 and MMP 9 protein expression and Smad2 phosphorylation. Results: Silibinin inhibits cell viability of HT-29 cell line at 24 hours in a dose-dependent manner. TGF-β increased the mRNA and protein expression of MMP-2, MMP-9, and phosphorylated Smad2 compared to controls. Pharmacological inhibition with silibinin markedly blocked TGF-β–induced MMP-2 and MMP-9 mRNA and protein expression and Smad2 phosphorylation. Conclusion: Silibinin decreased the cell viability of HT-29 cancer cells in a dose-dependent manner. Silibinin also inhibited TGF-β-stimulated MMP-2 and MMP-9 expression in HT-29 cells, possibly mediated with the Smad2 signaling pathway. https://bccr.tums.ac.ir/index.php/bccrj/article/view/347