Isolation, identification, and spheroids formation of breast cancer stem cells, therapeutics implications

Aims: Cancer stem cells (CSCs) are population of cells present in tumors, which can undergo self-renewal and differentiation. Three-dimensional (3D) in vitro models mimic features of the in vivo environment and provide unique perspectives on the behavior of stem cells. Materials and Methods: In this study, MDA-MB 231 cells were grown in two-dimensional (2D) monolayers and 3D spheroid formats and CSCs were isolated and grown as spheroids. The isolated CSCs were subjected to molecular studies for detection of CD44, CD24, MMP1, ABCG2, ALDH1, and GAPDH markers. Results: The monolayer of CSCs grown as spheroids showed better growth rate than the MDA-MB 231 cells, which shows the efficacy of 3D spheroid format of growing CSCs. CD44 show increased expression in spheroids compared to 2D culture of MDA-MB 231. ALDH1 a key marker of breast stem cells was highly expressed in BCSCs and MDA-MB 231 grown in 3D, while being absent in CSCs and MDA-MB 231 cells grown in 2D. Conclusions: The CSCs grown as spheroids showed better growth rate, which showed the efficacy of 3D spheroid format for CSCs culture. Since the association between BCSCs prevalence and clinical outcome and the evidence presented in this study support key roles of CSCs in breast cancer metastasis and drug resistance, it has been proposed that new therapies must target these cells.