Lizhen He

Dual-function nanosystem for synergetic cancer chemo-/radiotherapy through ROS-mediated signaling pathways

Radioresistance and limitation of irradiative dosage usually lead to failure in depletion of hypoxic tumors. Herein we developed multifunctional mesoporous silica nanoparticles (MSNs) as a carrier of a novel anticancer selenoamino acid (selenocystine, SeC), to achieve synergistic chemo-/radiotherapy. This multifunctional nanosystem effectively sensitizes cancer cells to X-ray radiotherapy. Conjugation of TAT cell penetrating peptide and transferrin to the surface of MSNs significantly enhances its internalization in cancer cells through receptor-mediated endocytosis. SeC@MSNs-Tf/TAT significantly enhanced X-ray-induced growth inhibition in cervical cancer cells by induction of apoptosis, mainly through death receptor-mediated extrinsic apoptotic pathway. Upon radiation, SeC@MSNs-Tf/TAT promoted intracellular ROS overproduction, which induced apoptotic cell death by affecting p53, AKT and MAPKs pathways. Furthermore, SeC@MSNs-Tf/TAT also significantly inhibited HeLa tumor growth in nude mice model through suppression of cell proliferation and induction of apoptosis. In vivo toxicity of the SeC@MSNs-Tf/TAT nanoparticles was investigated using the mouse model. The results of histological analysis revealed that, the nanoparticles did not show any obvious damage to these major organs under the experimental conditions, including heart, liver, spleen, lung and kidney. Taken together, this study demonstrates an effective and safe strategy for cancer-targeted chemo-/radiotherapy of human cancers.

RGD peptide-conjugated selenium nanoparticles: antiangiogenesis by suppressing VEGF-VEGFR2-ERK/AKT pathway

Angiogenesis is essential for tumorigenesis, progression and metastasis. Herein we described the synthesis of RGD peptide-decorated and doxorubicin-loaded selenium nanoparticles (RGD-NPs) targeting tumor vasculature to enhance the cellular uptake and antiangiogenic activities in vitro and in vivo. After internalization by receptor-mediated endocytosis, this nanosystem disassembled under acidic condition with the presence of lysozymes and cell lysate, leading to bioresponsive triggered drug release. Mechanistic investigation revealed that RGD-NPs inhibited angiogenesis through induction of apoptosis and cell cycle arrest in human umbilical vein endothelial cells (HUVECs) via suppression of VEGF-VEGFR2-ERK/AKT signaling axis by triggering ROS-mediated DNA damage. Additionally, RGD-NPs can inhibit MCF-7 tumor growth and angiogenesis in nude mice via down-regulation of VEGF-VEGFR2, effectively reduce the toxicity and prolong the blood circulation in vivo. Our results suggest that the strategy to use RGD-peptide functionalized SeNPs as carriers of anticancer drugs is an efficient way to achieve cancer-targeted antiangiogenesis synergism.

Designing Core–Shell Gold and Selenium Nanocomposites for Cancer Radiochemotherapy

Radiotherapy is an important regime for treating malignant tumors. There is interest in the development of radiosensitizers to increase the local treatment efficacy under a relatively low and safe radiation dose. In this study, we designed Au@Se-R/A nanocomposites (Au@Se-R/A NCs) as nano-radiosensitizer to realize synergistic radiochemotherapy based on the radiotherapy sensitization property of Au nanorods (NRs) and antitumor activity of Se NPs. In vitro studies show that the combined treatment of A375 melanoma cells in culture with NCs and X-ray induces cell apoptosis through alteration in expression of p53 and DNA-damaging genes and triggers intracellular ROS overproduction, leading to greatly enhanced anticancer efficacy. Further studies using clinically used radiotherapy equipment demonstrate that the combined treatment of NCs and X-ray significantly inhibits the tumor growth in vivo and shows negligible acute toxicity to the major organs. Taken together, this study provides a strategy for clinical translation application of nanomedicne in cancer radiochemotherapy.

Tailoring Particle Size of Mesoporous Silica Nanosystem To Antagonize Glioblastoma and Overcome Blood–Brain Barrier

The blood-brain barrier (BBB) is the main bottleneck to prevent some macromolecular substance entering the cerebral circulation, resulting the failure of chemotherapy in the treatment of glioma. Cancer nanotechnology displays potent applications in glioma therapy owing to their penetration across BBB and accumulation into the tumor core. In this study, we have tailored the particle size of mesoporous silica nanoparticles (MSNs) through controlling the hydrolysis rate and polycondensation degree of reactants, and optimized the nanosystem that could effectively penetrate BBB and target the tumor tissue to achieve enhanced antiglioma efficacy. The nanoparticle was conjugated with cRGD peptide to enhance its cancer targeting effect, and then used to load antineoplastic doxorubicin. Therefore, the functionalized nanosystem (DOX@MSNs) selectively recognizes and binds to the U87 cells with higher expression level of ανβ3 integrin, sequentially enhancing the cellular uptake and inhibition to glioma cells, especially the particle size at 40 nm. This particle could rapidly enter cancer cells and was difficult to excrete outside the cells, thus leading to high drug accumulation. Furthermore, DOX@MSNs exhibited much higher selectivity and anticancer activity than free DOX and induced the glioma cells apoptosis through triggering ROS overproduction. Interestingly, DOX@MSNs at about 40 nm exhibited stronger permeability across the BBB, and could disrupt the VM-capability of glioma cells by regulating the expression of E-cadherin, FAK, and MMP-2, thus achieving satisfactory antiglioblastoma efficacy and avoiding the unwanted toxic side effects to normal brain tissue. Taken together, these results suggest that tailoring the particle size of MSNs nanosystem could be an effective strategy to antagonize glioblastoma and overcome BBB.

Selenadiazole derivatives as theranostic agents for simultaneous cancer chemo-/radiotherapy by targeting thioredoxin reductase

The lack of early and timely diagnosis of tumors and the monitoring of their response to therapeutics have limited the successful cancer treatments. Theranostic agents are expected to realize the dual-purpose of simultaneous diagnosis and therapy for treatments of cancers. In the present study, we have examined the effects of the chemical structure of selenadiazole derivatives (SeDs) on their anticancer efficacy and radio-sensitization against clinically used X-rays. The results showed that the introduction of a nitro group (-NO2) into SeD-3 significantly enhanced the anticancer activity of SeDs. The higher lipophilicity endowed SeD-3 with higher cellular internalization ability, resulting in higher cellular uptake and anticancer efficacy. Specifically, the capacity of autofluorescence allowed the use of SeD-3 as a promising theranostic agent to directly monitor the cellular uptake, localization and biodistribution in vitro and in vivo. Interestingly, SeD-3 also significantly enhanced the sensitivity of HeLa cervical cells to X-ray-induced apoptosis by targeting the inhibition of TrxR and promoting intracellular ROS overproduction, which activated the downstream ROS-mediated signaling pathways to regulate cell apoptosis. Furthermore, SeD-3 exhibited satisfactory in vivo antitumor efficacy through the inhibition of tumor proliferation and induction of tumor cell apoptosis, and showed no toxicity to the main organs. Moreover, from the results of hematological analysis, we found that not only inhibiting the tumor growth, treatment of SeD-3 also alleviated the damage of liver, kidney and heart function of nude mice induced by HeLa xenografts. Taken together, this study demonstrates that SeDs could be further developed as an effective and safe theranostic agent for simultaneous cancer chemo-/radiotherapy.

Differential Effects of Polymer-Surface Decoration on Drug Delivery, Cellular Retention, and Action Mechanisms of Functionalized Mesoporous Silica Nanoparticles

Polymer-surface decoration has been found to be an effective strategy to enhance the biological activities of nanomedicine. Herein, three different types of polymers with a cancer-targeting ligand Arg-Gly-Asp peptide (RGD) have been used to decorate mesoporous silica nanoparticles (MSNs) and the functionalized nanosystems were used as drug carriers of oxaliplatin (OXA). The results showed that polymer-surface decoration of the MSNs nanosystem by poly(ethylene glycol) (PEG) and polyethyleneimine (PEI) significantly enhanced the anticancer efficacy of OXA, which was much higher than that of chitosan (CTS). This effect was closely related to the enhancement of the cellular uptake and cellular drug retention. Moreover, PEI@MSNs-OXA possessed excellent advantages in penetrating ability and inhibitory effects on SW480 spheroids that were used to simulate the in vivo tumor environments. Therefore, this study provides useful information for the rational design of a cancer-targeted MSNs nanosystem with polymer-surface decoration.

A Cancer-Targeted Nanosystem for Delivery of Gold(III) Complexes: Enhanced Selectivity and Apoptosis-Inducing Efficacy of a Gold(III) Porphyrin Complex

Construction of delivery systems for anticancer gold complexes to decrease their toxicity while maintaining efficacy is a key strategy to optimize and develop anticancer gold medicines. Herein, we describe cancer-targeted mesoporous silica nanoparticles (MSN) for delivery of a gold(III) porphyrin complex (Au-1 a@MSN(R)) to enhance its anticancer efficacy and selectivity between cancer and normal cells. Encapsulation of Au-1 a within mesoporous silica nanoparticles amplifies its inhibitory effects on thioredoxin reductase (TrxR), resulting in a loss of redox balance and overproduction of reactive oxygen species (ROS). Elevated cellular oxidative stress activates diversified downstream ROS-mediated signaling pathways, leading to enhanced apoptosis-inducing efficacy.

The rational design of NAMI-A-loaded mesoporous silica nanoparticles as antiangiogenic nanosystems

Angiogenesis is essential for tumorous progression and metastasis. The RGD (Arg-Gly-Asp acid) peptide has been demonstrated to be a remarkable targeting reagent and can be distinguished by the integrin receptor overexpressed in various human tumor cells. Mesoporous silica nanoparticles (MSNs) are one of the most promising carriers applied for delivery of drugs or genes. It is well known that NAMI-A is an excellent drug for antimigration of tumor cells. Targeting the tumor vasculature with RGD-modified nanomaterials is expected to be a promising strategy for cancer therapy. Herein we have investigated the antiangiogenic activity of NAMI-A-loaded and RGD peptide surface decorated mesoporous silica nanoparticles in vitro and in vivo. The results revealed that NAMI-A@MSN-RGD remarkably enhanced the cellular uptake and antiangiogenic efficacy in contrast to bare NAMI-A in vitro. The nanosystem of NAMI-A@MSN-RGD also exhibited inspiring antiangiogenic action in vivo. Furthermore, the RGD-functionalized nanodrug inhibited angiogenesis by means of apoptosis by triggering ROS-mediated DNA damage in human umbilical vein endothelial cells (HUVECs). Our results suggested that the use of RGD-peptide modified MSNs as a vehicle of anticancer drugs is an efficient way to construct cancer-targeted nanosystems with antiangiogenic activity.

Tailored mesoporous silica nanosystem with enhanced permeability of the blood–brain barrier to antagonize glioblastoma

Cancer-targeted drug delivery systems with permeability of the blood-brain barrier (BBB) have become of great interest for the rational design of high-efficiency anticancer agents. Herein, a tailored mesoporous silica nanoparticles (MSNs) nanosystem modified by RGD (arginine-glycine-aspartate) peptide was designed and tested for use as a carrier of anticancer agents, by using a novel organic selenium compound BSeC as a model molecule. As expected, the nanosystem (BSeC@MSNs-RGD) could effectively enhance the BBB permeability and the cellular uptake of BSeC in tumor cells. The internalized BSeC@MSNs-RGD triggered mitochondrial dysfunction and intracellular ROS overproduction, which subsequently activated the p53 and MAPKs pathways. Moreover, the nanosystem could inhibit the U87 tumor spheroids growth, significantly prolong the blood circulation time of the loaded drug in vivo and effectively reduce its in vivo toxicity. Taken together, this study provides a strategy for the rational design of a tailored nanomedicine with enhanced BBB permeability to treat human brain glioma.

Selenium substitution endows cystine with radiosensitization activity against cervical cancer cells

Radiotherapy has been the primary treatment for cancer along with chemotherapy and surgical therapy for decades. However, radiotherapy still fails to efficiently deracinate the hypoxic tumors because of their insensitivity to X-rays. In the present study, we report that selenocysteine (SeC), an analog of cystine (Cys) through selenium substitution of sulfur, could act as an effective radiosensitizer to enhance the anticancer efficacy of radiotherapy through induction of cancer cell apoptosis. By comparing the ROS generation activity of SeC and Cys, we found that selenium substitution significantly enhances the X-ray-induced ROS overproduction in human cervical cancer HeLa cells. Excess ROS could attack various components of DNA and activated downstream signaling pathways in HeLa cells. Specifically, SeC enhanced the radiation-induced phosphorylation of p53 and p38MAPK pathways, and down-regulation of phosphorylated AKT and ERK, and finally resulted in increased radiation sensitivity and inhibited tumor reproduction. Taken together, this study suggests that selenium substitution could be a novel strategy for design of cancer radiosensitizers.