Reversal of Chemoresistance via Staged Liberation of Chemodrug and siRNA in Hierarchical Response to ROS Gradient.

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) often leads to the failure of antitumor chemotherapy, and codelivery of chemodrug with P-gp siRNA (siP-gp) represents a promising approach for treating chemoresistant tumors. To maximize the antitumor efficacy, it is desired that the chemodrug be latently released upon completion of siP-gp-mediated gene silencing, which however, largely remains an unmet demand. Herein, core-shell nanocomplexes (NCs) are developed to overcome MDR via staged liberation of siP-gp and chemodrug (doxorubicin, Dox) in hierarchical response to reactive oxygen species (ROS) concentration gradients. The NCs are constructed from mesoporous silica nanoparticles (MSNs) surface-decorated with cRGD-modified, PEGylated, ditellurium-crosslinked polyethylenimine (RPPT), wherein thioketal-linked dimeric doxorubicin (TK-Dox2) and photosensitizer are coencapsulated inside MSNs while siP-gp is embedded in the RPPT polymeric layer. RPPT with ultrahigh ROS-sensitivity can be efficiently degraded by the low-concentration ROS inside cancer cells to trigger siP-gp release. Upon siP-gp-mediated gene silencing and MDR reversal, light irradiation is performed to generate high-concentration, lethal amount of ROS, which cleaves thioketal with low ROS-sensitivity to liberate the monomeric Dox. Such a latent release profile greatly enhances Dox accumulation in Dox-resistant cancer cells (MCF-7/ADR) in vitro and in vivo, which cooperates with the generated ROS to efficiently eradicate MCF-7/ADR xenograft tumors.

Cardiomyocyte-targeted anti-inflammatory nanotherapeutics against myocardial ischemia reperfusion (IR) injury.

Myocardial ischemia reperfusion (IR) injury is closely related to the overwhelming inflammation in the myocardium. Herein, cardiomyocyte-targeted nanotherapeutics were developed for the reactive oxygen species (ROS)-ultrasensitive co-delivery of dexamethasone (Dex) and RAGE small interfering RNA (siRAGE) to attenuate myocardial inflammation. PPTP, a ROS-degradable polycation based on PGE2-modified, PEGylated, ditellurium-crosslinked polyethylenimine (PEI) was developed to surface-decorate the Dex-encapsulated mesoporous silica nanoparticles (MSNs), which simultaneously condensed siRAGE and gated the MSNs to prevent the Dex pre-leakage. Upon intravenous injection to IR-injured rats, the nanotherapeutics could be efficiently transported into the inflamed cardiomyocytes via PGE2-assisted recognition of over-expressed E-series of prostaglandin (EP) receptors on the cell membranes. Intracellularly, the over-produced ROS degraded PPTP into small segments, promoting the release of siRAGE and Dex to mediate effective RAGE silencing (72%) and cooperative antiinflammatory effect. As a consequence, the nanotherapeutics notably suppressed the myocardial fibrosis and apoptosis, ultimately recovering the systolic function. Therefore, the current nanotherapeutics represent an effective example for the co-delivery and on-demand release of nucleic acid and chemodrug payloads, and might find promising utilities toward the synergistic management of myocardial inflammation. Electronic Supplementary Material: Supplementary material (experimental methods, RNA and primer sequences, 1H NMR spectra, FTIR spectrum, TEM images, zeta potential, drug loading content, RNA and drug release, cytotoxicity, etc.) is available in the online version of this article at 10.1007/s12274-022-4553-6.

Multivalency-assisted membrane-penetrating siRNA delivery sensitizes photothermal ablation via inhibition of tumor glycolysis metabolism.

The success of photothermal therapy (PTT) is often hampered by the thermo-resistance of tumor cells mediated by over-expressed heat shock proteins (HSPs). Herein, we developed a guanidine-rich, spherical helical polypeptide (DPP) with multivalency-assisted strong membrane penetrating capability, which mediated effective RNAi against tumor glycolysis metabolism to sensitize PTT. ICG was loaded into the internal cavity of DPP, and siRNA against pyruvate kinase M2 (siPKM2) was condensed by DPP to form positively charged nanocomplexes (NCs). The NCs were further coated with human serum albumin to enhance serum stability, prolong blood circulation, and improve tumor targeting. Due to its multivalent topology, DPP exhibited stronger membrane activity yet lower cytotoxicity than its linear analogue (LPP), thus enabling efficient PKM2 silencing in MCF-7 cells in vitro (~75%) and in vivo (~70%). The PKM2 silencing inhibited tumor glycolysis metabolism and further depleted the energy supply for HSPs production, thus overcoming the heat endurance of tumor cells to strengthen ICG-mediated photothermal ablation. Additionally, siPKM2-mediated energy depletion led to tumor cell starvation, which imparted synergistic anti-cancer effect with PTT. This study therefore provides a promising strategy for designing membrane-penetrating siRNA delivery materials, and it renders a unique RNAi-mediated anti-metabolic mechanism in sensitizing PTT and enabling starvation therapy.

Thermal-Responsive Carbon Monoxide (CO) Delivery Expedites Metabolic Exhaustion of Cancer Cells toward Reversal of Chemotherapy Resistance.

Multidrug resistance (MDR) is the main cause of chemotherapy failure, and the mechanism of MDR is largely associated with drug efflux mediated by the adenosine triphosphate (ATP)-binding cassette transporters. Herein, an NIR-light-triggered CO release system based on mesoporous Prussian blue nanoparticles (PB NPs) was developed to reverse MDR via CO-induced metabolic exhaustion. Pentacarbonyl iron (Fe(CO)5) as the CO producer was coupled to PB NPs via coordination interaction, and doxorubicin (Dox) was encapsulated into the pores of PB NPs. After layer-by-layer (LBL) coating, the NPs showed desired serum stability to enhance tumor accumulation. Upon tumor-site-specific NIR light (808 nm) irradiation, the nonlethal temperature elevation cleaved the Fe-CO bond to release CO. CO then expedited mitochondrial metabolic exhaustion to block ATP synthesis and inhibit ATP-dependent drug efflux, thus reversing MDR of the Dox-resistant MCF-7/ADR tumors to potentiate the anticancer efficacy of Dox. In the meantime, CO-mediated mitochondrial exhaustion could upregulate the proapoptotic protein, caspase 3, thus inducing cellular apoptosis and enabling a synergistic anticancer effect with chemotherapy. To the best of our knowledge, this is the first time MDR has been overcome using a CO delivery system. This study provides a promising strategy to realize an effective and safe treatment against MDR tumors and reveals new insights in the use of CO for cancer treatment.

Carbon monoxide (CO)-Strengthened cooperative bioreductive anti-tumor therapy via mitochondrial exhaustion and hypoxia induction.

Bioreductive chemodrugs require hypoxic conditions to activate their anti-cancer efficacy. The insufficient and heterogeneous hypoxic condition in tumor tissues hurdles the therapeutic potency of bioreductive chemodrugs. We herein report a NIR light-triggered CO release system based on mesoporous Prussian blue nanoparticles (PB NPs) to enable cancer-selective hypoxia aggravation and hypoxia-responsive activation of bioreductive anti-cancer drug, tirapazamine (TPZ). Pentacarbonyl iron (Fe(CO)5) was coupled to PB NPs via coordination interaction, and TPZ was encapsulated into the pores of PB NPs. To prolong blood circulation and improve tumor accumulation, the PB-CO-TPZ NPs were surface-decorated with PEG-NH2. Upon tumor site-specific light irradiation, the non-lethal photothermal effect of PB NPs released CO, which accelerated mitochondrial oxygen consumption and generated hypoxia to activate TPZ. The CO-induced mitochondrial exhaustion simultaneously led to cancer cell apoptosis, thus realizing synergistic anti-cancer effect with TPZ-mediated bioreductive chemotherapy. To the best of our knowledge, it is the first time to activate bioreductive chemotherapy using CO. This study thus provides a promising paradigm to realize effective and safe cancer treatment via precise manipulation of drug activities, and may open new insights in the use of CO for biomedical treatment.

Photodynamic therapy-mediated remote control of chemotherapy toward synergistic anticancer treatment.

Stimuli-responsive nanomedicine (NM) with an on-demand drug release property has demonstrated promising utility toward cancer therapy. However, sensitivity and cancer selectivity still remain critical challenges for intelligent NM, which will compromise its therapeutic efficacy and lead to undesired toxicity to normal tissues. Herein, we report a convenient and universal approach to spatiotemporally control the chemodrug release via the photodynamic therapy (PDT)-mediated alteration of the tumor microenvironment. An arylboronic ester (BE)-modified amphiphilic copolymer (mPEG-PBAM) was designed to form micelles and encapsulate doxorubicin (Dox) and hematoporphyrin (Hp). The Dox/Hp co-encapsulated micelles (PB-DH) were stable under normal physiological environment with a uniform size distribution (∼100 nm). In contrast, under tumor-specific light irradiation, extensive reactive oxygen species (ROS) will be generated from Hp in the tumor sites, thus quickly dissociating the micelles and selectively releasing the chemodrug Dox as a consequence of the ROS-mediated cleavage of the hydrophobic BE moieties on the polymers. As such, synergistic anti-cancer efficacy was achieved between the Dox-mediated chemotherapy and the Hp-mediated PDT. This study therefore provides a useful approach to realize the precise and selective control over chemodrug delivery, and it renders promising utilities for the programmable combination of PDT and chemotherapy.

Manipulating tumor hypoxia toward enhanced photodynamic therapy (PDT).

Photodynamic therapy (PDT) is considered a promising approach for the treatment of cancer and is achieved via the photosensitizer (PS)-mediated incomplete reduction of oxygen upon light irradiation, which generates high levels of reactive oxygen species (ROS) to induce potent vascular damage and to directly kill tumor cells. However, there is an undesirable impediment with this approach in that tumor tissues generally suffer from serious hypoxia, which significantly affects the efficiency of PDT. Additionally, PDT that consumes oxygen will further aggravate tumor hypoxia, thus potentially leading to multiple undesirable consequences, such as angiogenesis, tumor invasiveness, and tumor metastasis. This mini-review provides a comprehensive overview of the recent research progress on overcoming or utilizing tumor hypoxia to enhance the therapeutic efficacy of PDT.