Javad Firouzi
1,2,3 
, Fattah Sotoodehnejadnematalahi
4, Alireza Shokouhifar
3 , Mahsa Rahimi
3, Niloufar Sodeifi
5, Parisa Sahranavardfar
3, Masoumeh Azimi
3, Ehsan Janzamin
3, Majid Safa
1,2,6, Marzieh Ebrahimi
3* 1 Department of Tissue Engineering & Regenerative Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
2 Cellular and Molecular Research Centre, Iran University of Medical Sciences, Tehran, Iran
3 Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran 16635-148
4 Department of Biology, School of Basic Science, Science and Research Branch, Islamic Azad University, 1477893855
5 Department of Pathology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran 16635-148, Iran
6 Department of Hematology, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
Abstract
Introduction: Malignant breast cancer (BC) frequently contains a rare population of cells called cancer stem cells which underlie tumor relapse and metastasis, and targeting these cells may improve treatment options and outcomes for patients with BC. The aim of the present study was to determine the effect of silibinin on the self-renewal capacity, tumorgenicity, and metastatic potential of mammospheres.
Methods: The effect of silibinin on viability and proliferation of MCF-7, MDA-MB-231 mammospheres, and MDA-MB-468 cell aggregation was determined after 72-120 hours of treatment. Colony and sphere formation ability, and the expression of stemness, differentiation, and epithelial-mesenchymal-transition (EMT)-associated genes were assessed by reverse transcription-quantitative polymerase chain reaction (qRT-PCR) in mammospheres treated with an IC50 dose of silibinin. Additionally, the antitumor capacity of silibinin was assessed in vivo, in mice.
Results: The results of the present study showed that silibinin decreased the viability of all mammospheres derived from MCF-7, MDA-MB-231, and MDA-MB-468 cell aggregation in a dose-dependent manner. Colony and sphere-forming ability, as well as the expression of genes associated with EMT were reduced in mammospheres treated with silibinin. Additionally, the expression of genes associated with stemness and metastasis was also decreased and the expression of genes associated with differentiation were increased. Intra-tumoral injection of 2 mg/kg silibinin decreased tumor volumes in mice by 2.8 fold.
Conclusion: The present study demonstrated that silibinin may have exerted its anti-tumor effects in BC by targeting the BC stem cells, reducing the tumorgenicity and metastasis. Therefore, silibinin may be a potential adjuvant for treatment of BC.