Shikonin (SHK) has been proven to have a good anti-tumor effect. However, poor water solubility and low bioavailability limit its wide application in clinical practice. In this study, to overcome these drawbacks, RGD-modified shikonin-loaded liposomes (RGD-SSLs-SHK) were successfully prepared. It exhibited excellent physicochemical characteristics including particle size, zeta potential, encapsulation efficiency, and delayed release time. Meanwhile, the targeting activity of the RGD-modified liposomes was demonstrated by flow cytometry and confocal microscopy in the α_vβ₃-positive MDA-MB-231 cells. Besides exhibiting greater cytotoxicity in vitro, compared with non-targeted shikonin-loaded liposomes (SSLs-SHK), RGD-SSLs-SHK could also evidently induce apoptosis by decreasing the expression of Bcl-2 and increasing the expression of Bax. It could also inhibit cell proliferation, migration, invasion, and adhesion by reducing the expression of MMP-9 and the level of NF-κB p65, but did not affect the expression of MMP-2 in the MDA-MB-231 cells. Therefore, these findings indicated that the strategy to use RGD-modified liposomes as carriers for targeted delivery of shikonin is a very promising approach to achieve breast cancer targeted therapy.

In our recent study, hydrophobic cell-penetrating peptides (CPPs) were demonstrated as an effective method of improving cancer treatment. To provide more evidence and broaden the application range for this promising strategy of improving cancer treatment, novel hydrophobic CPP-modified (PFV-modified) nanoliposomes loaded with paclitaxel, termed PFV-Lip-PTX, were developed as a treatment for breast cancer. Physicochemical evaluations of PFV-Lip-PTX revealed spheroid-like regular vesicles of about 120 nm in diameter with negative charge. An in vitro release study indicated that PTX was released from the liposomes in a controlled and sustained manner. A cellular uptake study indicated that PFV-Lip-PTX exhibited higher internalization efficiency in MCF-7 cells than non-modified liposomes. It was also demonstrated that PFV modification improved the cytotoxicity of PTX via a hydrophobic interaction between the PFV-Lip and cell lipid membranes compared with non-modified liposomes. Moreover, in vivo studies demonstrated that the PFV-modified liposomes led to highly efficient targeting and accumulation in an MCF-7 xenograft tumor and improved the antitumor efficacy of PTX. Finally, PFV-Lip-PTX showed low systemic toxicity evidenced by fewer changes in the body weights of mice and no visible histological changes in major healthy organs. Therefore, our results indicate that PFV-Lip-PTX has great potential in tumor-targeting and effective antitumor treatment.