Penetratin is a classical cell-penetrating peptide with the potential to assist in the transmembrane delivery of proteins or drugs. However, the synthesis and application of cholesterol-penetratin (Chol-P) conjugates as nonviral delivery systems for microRNAs or drugs have not previously been reported. In this study, the amphiphilic Chol-P was shown to self-assemble into micelles and efficiently deliver miR-124 and obatoclax. The codelivered miR-124-M-Oba had a homogeneous particle size and a positive zeta potential. Treatment with miR-124 mincreased cytotoxicity, and cell proliferation, was promoted by miR-124 inhibitor-loaded micelles in MCF-7 human breast cancer cells. Moreover, the inhibitory effects on cell proliferation, colony formation, and cell migration were increased in the miR-124-M-Oba group compared to the miR-124-M group. miR-124-M-Oba induced higher levels of mitochondrial apoptosis via Bax and caspase-9 activation. In addition, we found that the cationic Chol-P and miR-124-M could potently induce autophagy, and miR-124 was degraded in the corresponding autophagolysosomes. The obatoclax encapsulated in miR-124-M-Oba could inhibit the degradation of miR-124 and p62 in autophagolysosomes, which consequently maintained the concentration of miR-124 in breast cancer cells. Furthermore, miR-124-M-Oba potently inhibited tumor growth in subcutaneous xenograft breast cancer models. In summary, the miR-124-M-Oba prepared in this work showed improved apoptosis induction and autophagic flux inhibitory effects in MCF-7 cells, and miR-124-M-Oba may have potential applications in breast cancer therapy.
Keywords: apoptosis; autophagic flux; breast cancer; miR-124; obatoclax; penetratin.