Background: Breast cancer (BC) is the most prevalent cancer among women worldwide with significant incidence and death rates. Nowadays, researchers hold that tumor formation, failure in therapy, and disease progression are all related to the presence of a small fraction of cancer cells with self-renewal capability known as “breast cancer stem cells” (BCSCs). Therefore, the study of this cancer cell population can be conducive to eradicating the tumor. The objective of the present study was to survey the existence and in vitro isolation of human BCSCs.
Method: An in vitro research study was conducted under controlled laboratory settings to isolate, enrich, and identify breast cancer stem cells. Briefly, fresh breast tumors were carried to the lab immediately after surgery, followed by mechanical and enzymatic digestion (2 mg/ml collagenase I). Then, digested samples were passed through cell strainers (70 and 40 μm), and obtained cell suspension was cultured under the serum-free medium supplemented with growth factors for 21 days. The expression of cluster of differentiation 44 (CD44) and cluster of differentiation 24 (CD24) surface markers was assessed using immunocytochemistry, and stem cell gene expression was analyzed via RT-PCR.
Results: BCSCs were able to survive in serum-free conditions and form floating spheres in vitro. Cells obtained from mammospheres expressed CD44 as the membranous and cytoplasmic pattern while CD24 expression was negative. Also, octameter-binding transcription factor 4 and SOX2 gene expression was observed in BCSCs.
Conclusion: The presence of stem cells was confirmed in Iranian women BC, and an efficient in vitro mammosphere culture model was used to enrich and propagate BCSCs. In our opinion, this in vitro model could be a suitable method for isolating and enriching BCSCs.