Conditioned media of tonsil derived mesenchymal stem cells shows different rates of cytotoxicity on solid cancer cells

Aims: Mesenchymal stem cells (MSCs) are the apple of the eye of cancer studies. It was indicated that the secreted factors, especially released by MSCs, have tumoral or anti-tumoral effects on tumor progression. MSCs obtained from different sources show different anti-tumoral effects, while MSCs originating from the same source also show different tumoral effects in different cancer cells. Here, we investigated the anti-tumor effects of soluble factors secreted from palatine tonsil MSCs (TMSC) as a new source of MSC on human lung carcinoma (A549) and pancreatic cancer (PANC-1) cell lines. Methods: Conditioned medium (CM) was obtained from TMSCs isolated from palatine tonsil tissue, and the cytotoxic effect of CM on the growth of A549 and PANC-1 in a dose-dependent manner was demonstrated by MTT analysis. In addition, the function of CM treatment on the cell cycle status of cancer cells and the apoptosis process were investigated through cell cycle analysis with propidium iodide (PI) and Annexin-V/PI detection method by flow cytometry analysis, respectively. Results: We demonstrated that TMSC-CM treatment significantly decreased the viability of A549 and PANC-1 cell lines in a dose-dependent manner post-48 hours. In addition, CM treatment differentially induced the apoptosis on A549 and PANC-1 cells and also, caused G2/M arrest in the cells. Conclusion: In light of these findings, our study is the first to show that TMSC-CM has an anti-tumoral effect by stimulating apoptosis on A549 and PANC-1 cells. These findings reveal that the usage of CM has a cell-free cellular therapeutic potential.