Exploring the potential of Mesenchymal stem cells to target Pancreatic cancer stem cells

Abstract

Cancer stem cells (CSCs) are known to be associated with chemoresistance, metastasis and recurrence of the tumor. Molecular diversity, intracellular signaling cross-talks and heterogeneity amongst CSCs play major roles in failure of monotherapy. In this context, deciphering molecular mechanisms involved in differential functional properties of CSCs becomes indispensable towards developing personalized medicine. We present the morphological (phase-contrast microscopy, fluorescent confocal microscopy, scanning electron microscopy), functional (migration assay, drug-sensitivity, cell surface markers) and proteomic (nLC-MS/MS) profiles of pancreatic cancer stem cells (pCSCs) against non-stem like tumor cells (MIAPaCa-2 and PanC-1) to depict the heterogeneity and identify specific drug targets in pancreatic tumor. Microscopic observations revealed relatively smaller, smoother, circular MIAPaCa-2 CSCs in comparison to larger, rough surfaced, oval shaped PanC-1 CSCs. Flow cytometric analysis shows that pCSCs exhibited higher percentages of double positive surface markers- CD24+44+ [Mia.CSCs:92.1±0.15%, Pan.CSCs:77.2±1.9%] in comparison to triple positive- CD24+44+CXCR4+ [Mia.CSCs:84.8±1.8%; Pan.CSCs:72.3±0.14%] and CD24+44+EpCAM+ [Mia.CSCs:44.6±2.4%; Pan.CSCs:61.5±1.7%]. Although trypan blue exclusion assay demonstrated lower proliferation of pCSCs than tumor cells (3 folds Vs 6 folds), yet a significantly high migratory capability (pand#8804;0.0001), up-regulated stem cell transcription factors (plt0.0005) and increased drug-resistance [higher IC50] were observed. Further, proteomic analysis showed enhanced expression of TGFand#946;/SMAD related proteins in MIAPaCa-2 CSCs, on the other hand, PanC-1 CSCs showed abundance of PI3K/AKT related proteins. This differential proteome composition shows the heterogeneity amongst pCSCs although both the cell lines harbor the same genetic mutations (KRAS/TP53). The results indicate targeting SMAD and AKT may reveal newer therapeutic options in pancreatic cancer.