Inhibition of Cancer Stem Cells Growth with Silibinin Encapsulated in Nanoparticles with Deregulation of miR-34a, miR-221, and miR-222

Background: Colorectal Cancer (CRC) is the most common malignant gastrointestinal cancer. Cancer stem cells (CSCs) are the major cause of cancer recurrence and cancer drug resistance. Silibinin, as an herbal compound, has anticancer properties. Objectives: The present study aimed to evaluate the antiproliferative effects of silibinin on HT29 stem-like cells (spheroids). Methods: In this study, antiproliferative and apoptotic properties of Silibinin encapsulated in Polymersome Nanoparticles (SPNs) were evaluated by MTT assay, propidium iodide (PI) /AnnexinV assay, cell cycle analysis, and DAPI (4',6-diamidino-2-phenylindole) staining. The expression of some miRNAs and their potential targets was evaluated by real-time reverse transcription-polymerase chain reaction (qRT-PCR). Results: IC50 of SPNs was determined at 28.13±0.78µg/ml after 24 h. SPNs (28µg/ml) induced apoptosis by 32.36% in HT29 cells after 24 h. DAPI staining indicated a decrease in stained nuclei after SPNs induction. SPNs treatment increased the expression of miR-34a, as well as P53, BAX, CASP9, CASP3, and CASP8. The downregulation of miR-221 and miR-222 was observed in SPNs treated cells. Moreover, SPNs decrease the expression level of CD markers in HT29 spheroids (cancer stem cells) compared to untreated spheroids. Spheroids were completely destroyed after 72 h treatment with SPNs (28µg/ml). Conclusion: As evidenced by the obtained results, SPNs can be used as an effective anticancer agent in multi-layer (cancer stem cells) and mono-layer cancerous cells with the upregulation of tumor suppressive miRs and genes, as well as downregulation of oncomiRs and oncogenes.