Acid-switchable nanoparticles induce self-adaptive aggregation for enhancing antitumor immunity of natural killer cells

Deficiency of natural killer (NK) cells shows a significant impact on tumor progression and failure of immunotherapy. It is highly desirable to boost NK cell immunity by upregulating active receptors and relieving the immunosuppressive tumor microenvironment. Unfortunately, mobilization of NK cells is hampered by poor accumulation and short retention of drugs in tumors, thus declining antitumor efficiency. Herein, we develop an acid-switchable nanoparticle with self-adaptive aggregation property for co-delivering galunisertib and interleukin 15 (IL-15). The nanoparticles induce morphology switch by a decomposition-metal coordination cascade reaction, which provides a new methodology to trigger aggregation. It shows self-adaptive size-enlargement upon acidity, thus improving drug retention in tumor to over 120 h. The diameter of agglomerates is increased and drug release is effectively promoted following reduced pH values. The nanoparticles activate both NK cell and CD8+ T cell immunity in vivo. It significantly suppresses CT26 tumor in immune-deficient BALB/c mice, and the efficiency is further improved in immunocompetent mice, indicating that the nanoparticles can not only boost innate NK cell immunity but also adaptive T cell immunity. The approach reported here provides an innovative strategy to improve drug retention in tumors, which will enhance cancer immunotherapy by boosting NK cells.

Antitumor activity of a novel survivin siRNA

Breast cancer resistance to therapy can result from expression of antiapoptotic genes. Survivin is an antiapoptotic gene that is over expressed in most human tumors. RNA interference using short interfering RNA [siRNA] can be used to specifically inhibit survivin expression. A novel siRNA targeting survivin was used to process MCF-7 cells. Cellular survivin mRNA and protein levels were determined by real-time qRT-PCR and Western blot, respectively. Cellular morphology and cell cycle were determined by fluorescence microscopy and flow cytometry. Cell proliferation was measured by MTT assay. Our data showed that the novel survivin-targeted siRNA could efficiently knockdown the expression of survivin, inhibit cell proliferation and cell cycle, especially at the G2/M checkpoint. These data suggest that the siRNA has potential for therapeutic applications