PANC-۱ cancer stem-like cell death with silybin encapsulated in polymersomes and deregulation of stemness-related miRNAs and their potential targets

Objective(s): Cancer stem cells (CSCs) have powerful self-renewal ability and tumor recurrence. Pancreatic ductal adenocarcinoma is a malignancy with high mortality rate and ˃۵% survival. Silybin has anticancer and hepatoprotective properties. We loaded silybin in PEG۴۰۰-OA (SPNs) and evaluated its cytotoxic effects on PANC-۱ cells and PANC-۱ CSCs.  Materials and Methods: Spheroids from PANC-۱ cells were obtained by the hanging drop method. Anti-proliferative and apoptotic functions of SPNs were evaluated in spheroids and non-spheroids with MTT, DNA fragmentation, PI and PI/AnnexinV assays. The expression of CD markers was assessed with flow cytometry. QRT-PCR was used to evaluate the expression of some miRNAs and targets.   Results: IC۵۰ of SPNs was identified to be ۵۰ µg/ml, ۴۵ µg/ml, and ۴۲µg/ml, respectively after ۲۴ hr, ۴۸ hr, and ۷۲ hr in PANC-۱ treated cells. PI staining and PI/AnnexinV assay showed that ~۲۰%, ~۶۰%, and ~۸۰%, of cells treated with ۳۰, ۵۰, and ۶۰ µg/ml of SPNs were in sub-G۱ and apoptosis phase, respectively. DNA degradation was confirmed after SPNS stimulation. CD۲۴, CD۴۴, and CD۱۳۳ expression decreased after SPNs treatment both in PANC-۱ spheroid cells and PANC-۱ cancer cell line. Under-expression of onco-miRs (miR-۲۱, miR-۱۵۵, and miR-۲۲۱), over-expression of several apoptotic potential targets of oncomiRs (Bax, Casp-۹, and P۵۳), over-expression of tumor suppressive-miRs (let-۷b, miR-۳۴a, and miR-۱۲۶), and under-expression of Bcl-۲ was found in SPNs-treated cells.  Conclusion: We suggest that silybin encapsulated in polymersomes (SPNs) may be useful as a complementary agent for destroying both pancreatic cancer cells and pancreatic CSCs  along with chemotherapeutic agents.

Keywords:

Cancer Stem cell , miRNA , Pancreatic Cancer , Polymersome , Silybin