PEGylated polyaminoacid-capped mesoporous silica nanoparticles for mitochondria-targeted delivery of celastrol in solid tumors

The major goal of cancer chemotherapy is to maximize the therapeutic efficacy of anticancer drugs, while minimizing their associated side effects. Celastrol (CST), which is extracted from the traditional Chinese medicinal plant Tripterygium wilfordii, has been reported to exhibit significant anticancer effects in various in vitro and in vivo cancer models. Nanoparticulate drug delivery systems could be employed to preserve and enhance the pharmacological effects of CST in cancer cells. Among these, mesoporous silica nanoparticles (MSNs) are one of the most promising drug delivery systems. MSNs possess the capability of passive accumulation within solid tumors, and could efficiently transport anticancer drugs to such tumors in a site-specific manner. In this study, PEGylated polyaminoacid-capped CST-loaded MSN (CMSN-PEG) showed controlled in vitro drug release behavior, and exhibited high in vitro cytotoxicity in different cancer cells. Compared to treatment with free CST, treatment with CMSN-PEG resulted in the increased expression of the apoptosis protein HIF-1α and proteins corresponding to mitochondrial apoptosis pathway. Importantly, CMSN-PEG remarkably reduced tumor burden with no toxicity to healthy cells in the SCC7 tumor-bearing xenograft model. Our results clearly demonstrate a promising potential of CMSN-PEG for the treatment of solid tumors.