Construction and evaluation of a nanosystem that combines acidification promoted chemodynamic therapy and intracellular drug release monitoring.

Triple-negative breast cancer (TNBC) is a highly invasive subtype of breast cancer that seriously affects women's physical and mental health. Chemodynamic therapy (CDT) induces cell death by specifically generating Fenton/Fenton-like reactions within tumor cells. However, the weak acidity of the tumor microenvironment (TME) greatly weakens the effectiveness of CDT. This work constructed a kind of P-CAIDF/PT nanoparticles (NPs), composed of two Pluronic F127 (PF127) based polymers: one was PF127-CAI (P-CAI), composed by connecting PF127 with the carbonic anhydrase IX (CA IX) inhibitor (CAI); the other was PF127-SS-TPE (PT), composed of PF127 and the aggregation-induced emission molecule, tetraphenylethylene (TPE), via the linkage of disulfide bonds. The two polymers were employed to construct the doxorubicin (DOX) and ferrocene (Fc) co-loaded P-CAIDF/PT NPs through the film dispersion method. After being administrated via i.v., P-CAIDF/PT could be accumulated in the TME by the enhanced permeability and retention (EPR) effect and engulfed by tumor cells. P-CAI induced intracellular acidification by inhibiting the overexpressed CA IX, thus promoting CDT by enhancing the Fc-mediated Fenton reaction. The acidification-enhanced CDT combined with the DOX-mediated chemotherapy could improve the therapeutic effect on TNBC. Moreover, P-CAIDF/PT also monitored the intracellular drug release processes through the fluorescence resonance energy transfer (FRET) effect depending on the inherent DOX/TPE pair. In conclusion, the P-CAIDF/PT nanosystem can achieve the combination therapy of acidification-enhanced CDT and chemotherapy as well as therapy monitoring, thus providing new ideas for the design and development of TNBC therapeutic agents.

Precise Interference of RNA-Protein Interaction by CRISPR-Cas13-Mediated Peptide Competition.

RNA-protein interactions are essential nodes of cellular regulatory circuits and play critical roles in normal physiology and disease. However, the precise roles of individual RNA-protein interactions remain elusive. Here we report a method for precise interference of endogenous RNA interacting with the RNA binding protein (RBP). TTP is an RBP that recognizes the AU-rich element (ARE) of mRNA via the binding domain TZF and represses gene expression. We engineer Cas13b, a class 2 type VI CRISPR-Cas endonuclease that exclusively targets RNA, to direct the peptide of TZF to the binding site and compete with endogenous TTP. We show that this tool specifically interferes with TTP interacting with the PIM1 and IL-2 3' UTR under the guidance of the gRNA specific for the AREs. Further, precise interference with the TTP-PIM1 interaction exerts a distinct effect on cell proliferation compared to transcriptome-wide interference. Thus, our work establishes a tool for deep understanding of RNA-RBP interactions.

Cinnamaldehyde and Doxorubicin Co-Loaded Graphene Oxide Wrapped Mesoporous Silica Nanoparticles for Enhanced MCF-7 Cell Apoptosis.

BACKGROUND: Combined chemotherapy is often affected by the different physicochemical properties of chemotherapeutic drugs, which should be improved by the reasonable design of co-loaded preparations. PURPOSE: A kind of simple but practical graphene oxide (GO) wrapped mesoporous silica nanoparticles (MSN) modified with hyaluronic acid (MSN@GO-HA) were developed for the co-delivery of cinnamaldehyde (CA) and doxorubicin (DOX), in order to enhance their combined treatment on tumor cells and reduce their application defects. METHODS: The MSNCA@GODOX-HA was constructed by MSNCA (loading CA via physical diffusion) and GODOX-HA (modified with HA and loading DOX via π-π stacking) through the electrostatic adsorption, followed by the physicochemical characterization, serum stability and in vitro release study. Cytotoxicity on different cells was detected, followed by the tumor cell uptake tests. The intracellular reactive oxygen species (ROS) changes, mitochondrial functions and activities of caspase-3/-9 in MCF-7 cells were also evaluated, respectively. RESULTS: The MSNCA@GODOX-HA nanoparticles kept stable in FBS solution and achieved pH-responsive release behavior, which was beneficial to increase the accumulation of CA and DOX in tumor cells to enhance the treatment. MSNCA@GODOX-HA exerted higher cytotoxicity to MCF-7 human breast cancer cells than H9c2 cardiac myocyte cells, which were not only attributed to the active targeting to tumor cells by HA, but also related with the activation of intrinsic apoptotic pathway in MCF-7 cells induced by CA, which was mediated by the specific ROS signal amplification and the interference with mitochondrial function. Moreover, the efficacy of DOX was also enhanced by the above process. CONCLUSION: The establishment of the MSNCA@GODOX-HA nanoparticles played a role in promoting strengths and restricting shortcomings of CA and DOX, thereby exerting their function and achieving efficient treatment against cancer.