Prostate cancer (PC) is one of the common malignant tumors of the male genitourinary system. Here, we constructed PTX@ZIF-8, which is a metal-organic-framework-encapsulated drug delivery nanoparticle with paclitaxel (PTX) as a model drug, and further modified the synthesized peptide dimer (Di-PEG₂₀₀₀-COOH) onto the surface of PTX@ZIF-8 to prepare a nanotargeted drug delivery system (Di-PEG@PTX@ZIF-8) for the treatment of prostate cancer. This study investigated the morphology, particle size distribution, zeta potential, drug loading, encapsulation rate, stability, in vitro release behavior, and cytotoxicity of this targeted drug delivery system, and explored the uptake of Di-PEG@PTX@ZIF-8 by human prostate cancer Lncap cells at the in vitro cellular level, as well as the proliferation inhibition and promotion of apoptosis of Lncap cells by the composite nanoparticles. The results suggest that Di-PEG@PTX@ZIF-8, as a zeolitic imidazolate frameworks-8-loaded paclitaxel nanoparticle, has promising potential for the treatment of prostate cancer, which may provide a novel strategy for the delivery system targeting prostate cancer.

Breast cancer as a “cold” tumor presents an immunosuppressive microenvironment and inferior T-lymphocyte infiltration, leading to poor efficacy of immune checkpoint blockade (ICB) therapies. It is urgent to develop new effective combination treatment strategies. Pyroptosis is an inflammatory form of programmed cell death mediated by Caspase-1/GSDMD pathway, which can cause immunogenic cell death (ICD) and boost the immunogenicity of tumor. In this study, an immune activator (siRNAPD-L1@HA-ZIF-8) was proposed based on metal-organic framework (ZIF-8) nanosystem carrying Zn2+ and PD-L1 siRNA to improve anti-tumor immunotherapy through evoking pyroptosis combined with immune checkpoint blockade. We found that siRNAPD-L1@HA-ZIF-8 could disintegrate under low pH and release massive amounts of Zn2+, leading to elevated intracellular osmolarity and ROS, eventually resulting in pyroptosis. Zn2+ overload-triggered pyroptosis caused ICD effect and promoted the maturation of dendritic cells and infiltration of T-lymphocytes, which reprogramed the immunoecology of tumor from “cold” to “hot” state. Meanwhile, the co-delivered PD-L1 siRNA decreased the expression of PD-L1 protein on the tumor surface, relieving immune evasion and recovering the recognition and killing ability of cytotoxic T-lymphocytes, further boosting the immune response. This research not only confirmed the potential of ZIF-8 intrinsically as an immune activator that induces pyroptosis in combination with encapsulated PD-L1 siRNA-mediated ICB therapy for the first time, but also adequately revealed the immune responses mechanism by multiple techniques. This study will provide new strategies for pyroptosis-mediated treatments for augmented anti-tumor immunotherapy and greatly inspire the further development of immune activators based on Zn2+ overload-triggered pyroptotic pathway.

Immune checkpoint inhibition (ICI) has become the mainstay of immunotherapy for the treatment of renal cell carcinoma (RCC). However, only a small portion of patients exhibit a positive response to PD-1/PD-L1 blockade therapy and the key reason is that RCC belongs to a vascular-rich tumor for promoting immunosuppression. Specifically, the dysfunctional tumor vasculature hinders effector T cell infiltration and induces immunosuppressive tumor microenvironment via the release of cytokine, which attenuates the therapeutic efficacy of ICI. Therefore, regulating abnormal tumor vasculature may be a promising strategy to overcome the immunosuppressive microenvironment and enhance ICI therapy. Here, we propose an NGR peptide-modified actively targeted liposome (Axi/siRNAPD−L1@NGR-Lipo) to encapsulate the anti-angiogenic agents Axitinib and PD-L1 siRNA to promote tumor vasculature normalization and relieve immune evasion for enhanced anti-tumor immunotherapy. With NGR-mediated tumor homing and active targeting, Axi/siRNAPD−L1@NGR-Lipo could act on tumor vascular endothelial cells to inhibit neo-angiogenesis, increase pericyte coverage and vascular perfusion, and normalize the structure and function of tumor blood vessels. Meanwhile, it also enhanced immune effector T cells and NK cells infiltration and reduced the proportion of immunosuppressive T cells including MDSC cells and Tregs, thus improving the tumor immunosuppressive microenvironment. Moreover, Axi/siRNAPD−L1@NGR-Lipo reduced the expression of PD-L1 protein in tumor cells, restored the recognition and killing ability of cytotoxic T cells, and relieved immune evasion. As expected, Axi/siRNAPD−L1@NGR-Lipo displayed superior anti-tumor and anti-metastatic efficacy in mice bearing RCC. Overall, this study demonstrated the important potential of regulating abnormal tumor vasculature to reshape the immunosuppressive microenvironment and boost ICI therapy, which represents a promising avenue for the synergistic anti-tumor with cancer immunotherapy.

Primary prostate cancer (PC) progresses to castration-resistant PC (CRPC) during androgen deprivation therapy (ADR) in early stages of prostate cancer. Thus, rather than blocking the androgen-related pathway further, docetaxel (DTX)-based therapy has become the most effective and standard first-line chemotherapy for CRPC. Although the therapy is successful in prolonging the survival of patients with CRPC, chemotherapy resistance develops due to the abnormal activation of the androgen receptor (AR) signaling pathway. Thus, to optimize DTX efficacy, continued maximum suppression of androgen levels and AR signaling is required. Here, we designed a prostate-specific membrane antigen (PSMA)-targeted nanosystem to carry both DTX and AR siRNA (Di-PP/AR-siRNA/DTX) for CRPC treatment. Specifically, DTX was encapsulated into the hydrophobic inner layer, and the AR siRNA was then condensed with the cationic PEI block in the hydrophilic outer layer of the PEI-PLGA polymeric micelles. The micelles were further coated with PSMA-targeted anionic polyethylene glycol-polyaspartic acid (Di-PEG-PLD). In vitro and in vivo results demonstrated that the resulting Di-PP/AR-siRNA/DTX exhibited prolonged blood circulation, selective targeting, and enhanced antitumor effects. Consequently, Di-PP/AR-siRNA/DTX holds great potential for efficient CRPC treatment by combining chemotherapy and siRNA silencing of androgen-related signaling pathways.

Micelle is mainly used for drug delivery and is prepared from amphiphilic block copolymers. It can be formed into an obvious core-shell structure that can incorporate liposoluble drugs. However, micelles are not suitable for the encapsulation of water-soluble drugs, and it is also difficult to maintain stability in the systemic circulation. To solve these problems, a type of polymer material, Fmoc-Lys-PEG and Fmoc-Lys-PEG-RGD, was designed and synthesized. These copolymers could self-assemble into micelles driven by π–π stacking and the hydrophobic interaction of 9-fluorenylmethoxycarbony (Fmoc) and, at the same time, form a framework for a hydrogen-bonding environment in the core. Mitomycin C (MMC), as a water-soluble drug, can be encapsulated into micelles by hydrogen-bonding interactions. The interaction force between MMC and the polymers was analyzed by molecular docking simulation and Fourier transform infrared (FTIR). It was concluded that the optimal binding conformation can be obtained, and that the main force between the MMC and polymers is hydrogen bonding. Different types of MMC nanoparticles (NPs) were prepared and the physicochemical properties of them were systematically evaluated. The pharmacodynamics of the MMC NPs in vitro and in vivo were also studied. The results show that MMC NPs had a high uptake efficiency, could promote cell apoptosis, and had a strong inhibitory effect on cell proliferation. More importantly, the as-prepared NPs could effectively induce tumor cell apoptosis and inhibit tumor growth and metastasis in vivo.

Background: Colorectal cancer (CRC) is one of the common malignant tumors. Chemotherapeutic agents represented by doxorubicin (DOX) are common adjuvant therapies for patients with advanced CRC. However, DOX suffers from dose-dependent cardiotoxicity and myelosuppression due to a lack of targeting and specificity, which severely limits its clinical application. Methods: Herein, we constructed a zeolitic imidazolate framework-8 (ZIF-8) modified by a novel peptide (LT peptide) to deliver the chemotherapeutic drug doxorubicin (DOX) for the targeted treatment of CRC. Results: In this study, LT-PEG@DOX@ZIF-8 nanoparticles were prepared by a simple method with suitable particle size and zeta potential, which were also capable of pH-responsive drug release. In vitro assays exhibited that LT-PEG@DOX@ZIF-8 nanoparticles were effectively taken up by C26 cells, significantly inhibited cell proliferation, and induced apoptosis. Furthermore, in mice models with colorectal tumors, LT-PEG@DOX@ZIF-8 nanoparticles also displayed specific tumor aggregation and exerted anti-tumor effects to prolong the survival of the mice. Conclusions: In conclusion, LT-PEG@DOX@ZIF-8 provides a promising strategy for the delivery of DOX to effectively treat CRC.