Novel MicroRNA Targets and Targeting Technology to Modulate Pancreatic Stellate Cells in Pancreatic Tumor

Pancreatic stellate cells (PSCs) are the main producers of the pancreatic tumor stroma, which in turn, promote tumor growth and metastasis. During carcinogenesis microRNA (miRNA) dysregulation is not limited to the cancer cells but also occurs in PSCs. We hypothesized that inhibition of the upregulated miRNA in PSCs might inhibit the PSC-mediated tumor-promoting effects. In this study, we found miR-199a and -214 as novel targets in TGF-ß-activated human PSCs. Transfection of anti-miR-199a or -214 significantly inhibited the TGFß-induced differentiation, as confirmed by the inhibition of PSC markers (α-SMA, collagen, PDGFßR). Also, transfection of these antagomiRs significantly reduced migration and proliferation of PSCs. To study the paracrine effect of PSCs on Panc-1 tumor cells, we generated spheroids of Panc-1 and PSCs using the hanging-drop method. We found that spheroids containing PSCs transfected with anti-miR-199a or -214 were smaller in size compared to that with control PSCs. Next, PSC-conditioned medium induced tumor cells proliferation and endothelial tube formation and these paracrine effects were abrogated with PSCs transfected with anti-miR-199a or 214. These data confirmed that miR-199a and 214 are potential therapeutic candidates in PSCs. Furthermore, to deliver antagomiRs preferably to PSCs, we developed a cell-penetrating peptide based delivery system. This peptide makes NanoComplexes with anti-miR oligonucleotides and delivers them into PSCs with a high efficiency (80%). In contrast, Panc-1 cells showed a weaker uptake. High transfection of NanoComplexes in PSCs was likely due to the abundance of syndecans (proteoglycans) in PSCs compared to Panc-1, as shown with mRNA expression. In conclusion, we have found novel therapeutic miRNA targets in PSCs and also developed a technology to deliver anti-miRNA oligonucleotide to PSCs, which in combination can be applied for inhibiting PSC activity to treat pancreatic tumor.