Fig. 7

Differentiation of CiSCs reveals multilineage differentiation potential. a Real-time qRT-PCR analysis of various differentiation markers for the three germ layers indicating the multilineage differentiation potential of CiSCs. β-actin mRNA used to normalize the variability in template loading. Data reported on a log-10 scale as mean ± SD. b Oct-4 protein expression levels decrease with number of days (0–21) in culture when exposed to 10% FBS, as determined by intracellular flow cytometry staining, indicating differentiation of CiSCs in the presence of FBS. c Confocal immunofluorescence images for Desmin (green) and α-SMA (red) of control BM-MSCs and MCF7, Hela, and HepG2 CiSCs. Nuclei stained with DAPI (blue). Scale bars = 60 μM. d Flow cytometry overlay histogram analysis of CD34, CD19, CD45, and Oct-4 in BM-MSCs and MCF7, Hela, and HepG2 CiSCs following exposure to 10% FBS for 7 days, showing an increase in cell surface expression levels of CD34, CD19, and CD45 but a decrease in intracellular expression of Oct-4. For comparison, isotype control (black) was used to define the positive and negative population for each marker. e Schematic representation of the proposed model for MSC reprogramming to a cancer stem-like cell in the tumor microenvironment. Depiction of the proposed model in which MSCs are recruited to the tumor microenvironment where microenvironmental stimulus such as TGF-β can induce recruited MSCs to undergo reprogramming to a cancer stem cell phenotype enabling tumor progression and metastasis and modulating drug sensitivity. Taken together, these results suggest a critical role for the tumor microenvironment in determining the fate of the MSCs recruited to the tumor microenvironment. BM-MSC bone marrow mesenchymal stem cell, CSC cancer stem cell, CiSC cancer-induced stem cell, TGF-β transforming growth factor beta