Sulforaphane Mediates Glutathione Depletion via Polymeric Nanoparticles to Restore Cisplatin Chemosensitivity

Platinum (Pt)-based chemotherapy is a broadly used therapeutic regimen against various cancers. However, the insufficient cellular uptake, deactivation by thiol-containing species and nonspecific distribution of cisplatin (CDDP) result in its low chemosensitivity as well as systemic side effects, which can largely constrain the employment of CDDP in clinical treatment. To circumvent these problems, in this study, polymeric nanoparticles were utilized to codeliver a water-soluble CDDP derivative, poly(γ,l-glutamic acid)-CDDP conjugate, and a naturally occurring compound derived from broccoli, sulforaphane, which can achieve efficient glutathione (GSH) depletion, to improve the accumulation of CDDP in cancer cells. Results show that compared with combinational treatment of CDDP and SFN, the nanoparticles were more effectively internalized and could significantly reduce GSH content in breast cancer cells, leading to a notable increase in DNA-bound Pt and DNA damage-induced apoptosis. Moreover, in an orthotopic breast cancer model, the nanoparticles achieved a significantly higher tumor accumulation and exhibited a more powerful antitumor activity. Finally, this nanoenhanced chemotherapy was further confirmed in a liver cancer model with high-expression of GSH. Taken together, this sulforaphane-based nanostrategy holds great promise to enhance the sensitivity and therapeutic efficacy of Pt-based chemotherapy.

Methylation of SLFN11 promotes gastric cancer growth and increases gastric cancer cell resistance to cisplatin

Background and Aim: Human SLFN11 gene encodes a protein with structural similarity to RNA helicases, which was reported to sensitize cancer cells to DNA-damaging agents. This study explored the epigenetic regulation and mechanism of SLFN11 in human gastric cancer.

Methods: Eight human gastric cancer cell lines and 201 cases of primary gastric cancer were analyzed. Methylation specific PCR, flow cytometry, xenograft mouse model and siRNA technique were employed.

Results: SLFN11 was methylated in 29.9% (60/201) of primary gastric cancer. The expression of SLFN11 was regulated by promoter region methylation. Methylation of SLFN11 was significantly associated with tumor size (p < 0.05). SLFN11 suppressed gastric cancer growth both in vitro and in vivo and enhanced the ability of cisplatin to induce S-phrase arrest and apoptosis in gastric cancer cells.

Conclusions: SLFN11 is frequently methylated in human gastric cancer, and its expression is regulated by promoter region methylation. Our results demonstrate that SLFN11 is a tumor suppressor in human gastric cancer, and methylation of SLFN11 may serve as a cisplatin resistant marker in human gastric cancer.

Smart Nanotherapeutic Targeting of Tumor Vasculature

The past decades have witnessed the development of a field dedicated to targeting tumor vasculature for cancer therapy. In contrast to conventional chemotherapeutics that need to penetrate into tumor tissues for killing tumor cells, the agents targeting tumor vascular system have two major advantages: direct contact with vascular endothelial cells or the blood and less possibility to induce drug resistance because of high gene stability of endothelial cells. More specifically, various angiogenesis inhibitors (AIs) and vascular disrupting agents (VDAs) that block tumor blood supply to inhibit tumor progression, some of which have been applied clinically, have been described. However, off-target effects and high effective doses limit the utility of these formulations in cancer patients. Thus, new strategies with improved therapeutic efficacy and safety are needed for tumor vessel targeting therapy. With the burgeoning developments in nanotechnology, smart nanotherapeutics now offer unprecedented potential for targeting tumor vasculature. Based on specific structural and functional features of the tumor vasculature, a number of different nanoscale delivery systems have been proposed for cancer therapy. In this Account, we summarize several distinct strategies to modulate tumor vasculature with various smart nanotherapeutics for safe and effective tumor therapy developed by our research programs. Inspired by the blood coagulation cascade, we generated nanoparticle-mediated tumor vessel infarction strategies that selectively block tumor blood supply to starve the tumor to death. By specifically delivering thrombin loaded DNA nanorobots (Nanorobot-Th) into tumor vessels, an intratumoral thrombosis is triggered to induce vascular infarction and, ultimately, tumor necrosis. Mimicking the coagulation cascade, a smart polymeric nanogel achieves permanent and peripheral embolization of liver tumors. Considering the critical role of platelets in maintaining tumor vessel integrity, a hybrid (PLP-D-R) nanoparticle selectively depleting tumor-associated platelets (TAP) to boost tumor vessel permeability was developed for enhancing intratumoral drug accumulation. In addition, benefiting from a better understanding of the molecular and cellular underpinnings of vascular normalization, several tumor acidity responsive nanotherapeutics, encapsulating therapeutic peptides, and small interfering RNA were developed to correct the abnormal features of the tumor vasculature. This made the tumor vessels more efficient for drug delivery. While we are still exploring the mechanisms of action of these novel nanoformulations, we expect that the strategies summarized here will offer a promising platform to design effective next-generation nanotherapeutics against cancer and facilitate the clinical translation of smart nanotherapeutics that target tumor vasculature.

Synthesis and Imaging of Biocompatible Graphdiyne Quantum Dots

Graphdiyne has attracted much interest from researchers for their potential applications in energy storage, catalysis, and biomedical areas. As one of the derivatives of graphdiyne, graphdiyne quantum dots (GDQDs) may possess superior bioactivity due to active acetylene units. However, the biological application of biocompatible GDQDs have not been reported so far. Herein, GDQDs with uniform size and good crystallization were prepared via a classical solvothermal method. The GDQDs exhibit excitation- and pH-dependent fluorescence emission as well as superior photostability, demonstrating their potential for bioimaging. The GDQDs demonstrate efficient cellular uptake and cell imaging without induction of detectable cytotoxic effects in vitro. Systematical safety evaluation further confirmed good biocompatibility of the GDQDs in vivo. Our study preliminarily validates the application of the GDQDs in biomedicine and encourages more thorough studies for better realizing the potential of GDQDs.

Dopamine Delivery via pH-Sensitive Nanoparticles for Tumor Blood Vessel Normalization and an Improved Effect of Cancer Chemotherapeutic Drugs

Tumor blood vessels have been reported to be abnormal in both structure and function compared with those in normal tissues, leading to a hostile microenvironment and inadequate antitumor drug delivery. Dopamine, a chemical messenger, is proven to inhibit angiogenesis and improve tumor vessel normalization. Here, a mesoporous silicon nanoparticle (MSN) is constructed that is responsive to the weakly acidic pH of the tumor extracellular matrix for steady delivery and tumor-localized release of dopamine. Then MSNs are functionalized with amine conjugated phenylboronicacid molecules, and dopamine is loaded by reacting with phenylboronic acid. In a weakly acidic environment, MSNs intelligently release dopamine due to the hydrolysis of boronic-ester bond between dopamine and phenylboronic acid, resulting in an evident inhibition of vascular endothelial cell migration and tubule formation. It is shown that loading of dopamine into the functional MSNs significantly prolong the circulatory half-life of this small molecule. After intravenous injection to tumor bearing mice, this nanoformulation induce tumor blood vessel normalization, thereby improving the antitumor chemotherapeutic efficacy of doxorubicin. This study demonstrates that the pH-responsive MSN offers great potential for delivery of dopamine in vivo and the normalization of tumor vessels by dopamine can provide an auxiliary treatment for cancer chemotherapeutic drugs.

Targeting Delivery of Platelets Inhibitor to Prevent Tumor Metastasis

Activated platelets have a high affinity for tumor cells, and consequently, they can protect tumor cells from environmental stress and immune attacks. Therefore, preventing platelet-tumor cell interaction can lead to the elimination of circulating tumor cells via natural killer cells and finally metastasis inhibition. It is also shown that CREKA (Cys-Arg-Glu-Lys-Ala), a tumor-homing pentapeptide, targets fibrin-fibronectin complexes that are found on the tumor stroma and the vessel walls. In this study, we linked CREKA to Ticagrelor, a reversible antagonist of the P2Y₁₂ receptor on platelets. In vitro experiments indicated that CREKA-Ticagrelor could not only inhibit the platelet-induced migration of tumor cells with an invasive phenotype but also prevent tumor-platelet interaction. In vivo antitumor and antimetastasis results of this drug showed that CREKA-Ticagrelor could specifically target the tumor tissues within 24 h post intravenous injection and suppress lung metastasis. Meanwhile, by having this antiplatelet drug targeted, its side effects were minimized, and bleeding risk was decreased. Thus, CREKA-Ticagrelor offers an efficient antimetastatic agent.

Engineering Biomimetic Platesomes for pH-Responsive Drug Delivery and Enhanced Antitumor Activity

Biomimetic camouflage, i.e., using natural cell membranes for drug delivery, has demonstrated advantages over synthetic materials in both pharmacokinetics and biocompatibility, and so represents a promising solution for the development of safe nanomedicine. However, only limited efforts have been dedicated to engineering such camouflage to endow it with optimized or additional properties, in particular properties critical to a "smart" drug delivery system, such as stimuli-responsive drug release. A pH-responsive biomimetic "platesome" for specific drug delivery to tumors and tumor-triggered drug release is described. This platesome nanovehicle is constructed by merging platelet membranes with functionalized synthetic liposomes and exhibits enhanced tumor affinity, due to its platelet membrane-based camouflage, and selectively releases its cargo in response to the acidic microenvironment of lysosomal compartments. In mouse cancer models, it shows significantly better antitumor efficacy than nanoformulations based on a platesome without pH responsiveness or those based on traditional pH-sensitive liposomes. A convenient way to incorporate stimuli-responsive features into biomimetic nanoparticles is described, demonstrating the potential of engineered cell membranes as biomimetic camouflages for a new generation of biocompatible and efficient nanocarriers.

Tumor-Specific Silencing of Tissue Factor Suppresses Metastasis and Prevents Cancer-Associated Hypercoagulability

Within tumors, the coagulation-inducing protein tissue factor (TF), a major initiator of blood coagulation, has been shown to play a critical role in the hematogenous metastasis of tumors, due to its effects on tumor hypercoagulability and on the mediation of interactions between platelets and tumor cells. Targeting tumor-associated TF has therefore great therapeutic potential for antimetastasis therapy and preventing thrombotic complication in cancer patients. Herein, we reported a novel peptide-based nanoparticle that targets delivery and release of small interfering RNA (siRNA) into the tumor site to silence the expression of tumor-associated TF. We showed that suppression of TF expression in tumor cells blocks platelet adhesion surrounding tumor cells in vitro. The downregulation of TF expression in intravenously administered tumor cells (i.e., simulated circulating tumor cells [CTCs]) prevented platelet adhesion around CTCs and decreased CTCs survival in the lung. In a breast cancer mouse model, siRNA-containing nanoparticles efficiently attenuated TF expression in the tumor microenvironment and remarkably reduced the amount of lung metastases in both an experimental lung metastasis model and tumor-bearing mice. What's more, this strategy reversed the hypercoagulable state of the tumor bearing mice by decreasing the generation of thrombin-antithrombin complexes (TAT) and activated platelets, both of which are downstream products of TF. Our study describes a promising approach to combat metastasis and prevent cancer-associated thrombosis, which advances TF as a therapeutic target toward clinic applications.

Reversing tumor stemness via orally targeted nanoparticles achieves efficient colon cancer treatment

The acquisition of stemness in colorectal cancer (CRC) attributed to the recurrence and metastasis in CRC treatment. Therefore, targeting the stemness of CRC forms a basis for the development of novel therapeutic approaches. However, the pain and systemic side effect from long-term of venipuncture injection remain great challenges to neoplastic treatment. Here, we introduce an oral drug delivery system for sustained release of BMI-1 inhibitor (PTC209) that reverses the stemness of CRC to overcome these obstacles. In this system, nanoparticles modified with hyaluronic acid (HA) showed high-affinity to CD44/CD168 overexpressed-CRC cells, and efficiently targeted to tumor site in a metastatic orthotropic colon cancer mouse model by oral administration. Significantly, the observed tumor growth inhibition is accompanied by decreased expression of stemness markers in the tumor tissues. Furthermore, HA-NPs-PTC209 also significantly prevented metastasis to the gastrointestinal system, while failing to exhibit acute side effects. In summary, we have developed an orally active, easily synthesized nanomedicine that shows promise for the treatment of colon cancer.

Cooperatively Responsive Peptide Nanotherapeutic that Regulates Angiopoietin Receptor Tie2 Activity in Tumor Microenvironment To Prevent Breast Tumor Relapse after Chemotherapy

Expressed in macrophages and endothelial cells, the receptor for angiopoietin, tyrosine kinase with immunoglobulin and epidermal growth factor homology-2 (Tie2), is required for the reconstruction of blood vessels in tumor recurrence after chemotherapy. Thus, small therapeutic peptides that target and block Tie2 activity are promising as a therapeutic for the prevention of tumor relapse after chemotherapy. However, such small peptides often have low bioavailability, undergo rapid enzymatic degradation, and exhibit a short circulation half-life, making them ineffective in cancer therapy. Herein, we designed a dual-responsive amphiphilic peptide (mPEG₁₀₀₀-K(DEAP)-AAN-NLLMAAS) to modify the small peptide T4 (NLLMAAS) as a Tie2 inhibitor, endowing it with the ability to endure in circulation and specifically target tumor tissue. The ultimate nanoformulation (P-T4) releases T4 in response to the combination of the acidic tumor microenvironment and the presence of legumain, which is commonly overexpressed in tumor tissue. Compared with free T4, P-T4 decreases vessel density significantly (free T4: 2.44 ± 1.20%, P-T4: 0.90 ± 0.75%), delays tumor regrowth after chemotherapy (free T4: 43.2 ± 11.8%, P-T4: 63.6 ± 13.9%), and reduces distant metastasis formation (free T4: 4.50 ± 2.40%, P-T4: 0.67 ± 0.32%). These effects of P-T4 are produced by the local blockage of Tie2 signals in Tie2-positive macrophages and endothelial cells. In addition to describing a potential strategy to enhance circulation half-life and the accumulation of an active peptide at tumor sites, our approach exemplifies the successful targeting of multiple cell types that overexpress a key molecule in conditions associated with tumors.

An Extendable Star-Like Nanoplatform for Functional and Anatomical Imaging-Guided Photothermal Oncotherapy

Combining informative imaging methodologies with effective treatments to destroy tumors is of great importance for oncotherapy. Versatile nanotheranostic agents that inherently possess both diagnostic imaging and therapeutic capabilities are highly desirable to meet these requirements. Here, a simple but powerful nanoplatform based on polydopamine-coated gold nanostar (GNS@PDA), which can be easily diversified to achieve various function extensions, is designed to realize functional and anatomical imaging-guided photothermal oncotherapy. This nanoplatform intrinsically enables computed tomography/photoacoustic/two-photon luminescence/infrared thermal tetramodal imaging and can further incorporate fibroblast activation protein (FAP, a protease highly expressed in most of tumors) activatable near-infrared fluorescence imaging and Fe³⁺-based magnetic resonance imaging for comprehensive diagnosis. Moreover, GNS@PDA exhibits excellent photothermal performance and efficient tumor accumulation. Under the precise guidance of multimodal imaging, GNS@PDA conducts homogeneous photothermal ablation of bulky solid tumors (∼200 mm³) in a xenograft mouse model. These results suggest great promise of this extendable nanoplatform for cancer theranostics.

Peptide Self-Assembly Nanoparticles Loaded with Panobinostat to Activate Latent Human Immunodeficiency Virus

Highly active antiretroviral therapy (HAART) can turn human immunodeficiency virus-1 (HIV-1) infection into a controllable chronic disease, but because of the presence of an HIV reservoir, it cannot completely eliminate the virus in HIV-infected patients. The activation of latent reservoirs is the key to the successful treatment of acquired immune deficiency syndrome (AIDS). As a class of latency-reversing agents (LRAs), histone deacetylase inhibitors (HDACis), such as panobinostat, have been the most widely investigated, but most of them have resulted in only a modest and transient activation of HIV latency. To improve the potency of latency activation, an injectable peptide self-assembly nanoparticle loaded with panobinostat (PNP-P) was designed with the ability to efficiently penetrate the cell to achieve better drug delivery and activation of latent HIV. The results confirmed that these nanoparticles could activate latently infected cells in vitro and in vivo and activate peripheral blood mononuclear cells (PBMCs) from latently infected patients ex vivo. Increased cellular drug uptake made the PNP-P more effective than panobinostat alone. Therefore, this strategy demonstrates that nanotechnology can help improve the activation of latent HIV, and this study lays a foundation for further development of LRA delivery systems for use against an HIV reservoir.

Biomimetic Metal-Organic Framework Nanoparticles for Cooperative Combination of Antiangiogenesis and Photodynamic Therapy for Enhanced Efficacy

Photodynamic therapy (PDT) is a promising anticancer treatment and is clinically approved for different types of tumors. However, current PDT suffers several obstacles, including its neutralization by excess glutathione (GSH) in the tumor tissue and its strongly proangiogenic tumor response. In this work, a biomimic, multifunctional nanoparticle-based PDT agent, combining a tumor-targeted photosensitizer with GSH scavenging and antiangiogenesis therapy, is developed. A porphyrinic Zr-metal-organic framework nanoparticle is used simultaneously as the photosensitizer and the delivery vehicle of vascular endothelial growth factor receptor 2 (VEGFR2) inhibitor apatinib. The core nanoparticles are wrapped in MnO₂ to consume the intratumoral GSH and then decorated with a tumor cell membrane camouflage. After intravenous administration, the nanoparticles selectively accumulate in tumor through homotypic targeting mediated by the biomimic decoration, and the combination of enhanced PDT and antiangiogenic drug significantly improves their tumor inhibition efficiency. This study provides an integrated solution for mechanism-based enhancement of PDT and demonstrates the encouraging potential for multifunctional nanosystem applicable for tumor therapy.

MiRNA-106a promotes breast cancer progression by regulating DAX-1

OBJECTIVE

The aim of this study was to explore the expression of microRNA-106a in breast cancer (BC) and to further investigate its role in BC development and the potential regulatory mechanism.

PATIENTS AND METHODS

72 pairs of BC tissues and para-cancerous tissues were collected, and microRNA-106a expression was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The relationship between microRNA-106a expression and BC pathological parameters was analyzed. Meanwhile, the expression of microRNA-106a in BC cells was verified by qRT-PCR as well. In addition, microRNA-106a knockdown model was constructed by transfecting small interfering RNA in BC cell lines including MCF-7 and SKBR3. Subsequently, the effects of microRNA-106a on biological functions of BC cells were analyzed by cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EDU), and transwell invasion and migration assays, respectively. Finally, the underlying mechanism was explored by cellular rescue experiment.

RESULTS

QRT-PCR results illustrated that microRNA-106a expression in BC tissues was markedly higher than that of normal tissues. Patients with high expression of microRNA-106a exhibited significantly higher tumor stage as well as higher incidence of lymph node metastasis and distant metastasis when compared with those with low expression. Cell proliferation, invasion, and migration abilities in microRNA-106a inhibitor group were markedly decreased when compared with control group. Subsequent experiments demonstrated that DAX-1 expression was reduced in BC cell lines and tissues. Moreover, DAX-1 expression was negatively correlated with microRNA-106a expression. In addition, a recovery experiment found that microRNA-106a and DAX-1 had mutual regulation, which could affect the malignant progression of BC.

CONCLUSIONS

We found that the expression of microRNA-106a was significantly increased in BC. Meanwhile, microRNA-106a expression was closely related to BC stage, distant metastasis, lymph node metastasis, and poor prognosis. Therefore, microRNA-106a promoted the invasion, migration, and proliferation of BC by targeting DAX-1.

Targeted Co-delivery of the Iron Chelator Deferoxamine and a HIF1α Inhibitor Impairs Pancreatic Tumor Growth

Rapidly growing cancer cells exhibit a strong dependence on iron for their survival. Thus, iron-removing drugs, iron chelators, have potential applications in cancer treatment. Deferoxamine (DFO) is an efficient iron chelator, but its short circulation half-life and ability to induce hypoxia-inducible factor 1α (HIF1α) overexpression restricts its use as an antitumor agent. In the present study, we first found that a pattern of iron-related protein expression favoring higher intracellular iron closely correlates with shorter overall and relapse-free survival in pancreatic cancer patients. We subsequently found that a combination of DFO and the HIF1α inhibitor, lificiguat (also named YC1), significantly enhanced the antitumor efficacy of DFO in vitro. We then employed transferrin receptor 1 (TFR1) targeting liposomes to codeliver DFO and YC1 to pancreatic tumors in a mouse model. The encapsulation of DFO prolonged its circulation time, improved its accumulation in tumor tissues via the enhanced permeability and retention (EPR) effect, and facilitated efficient uptake by cancer cells, which express high level of TFR1. After entering the tumor cells, the encapsulated DFO and YC1 were released to elicit a synergistic antitumor effect in subcutaneous and orthotopic pancreatic cancer xenografts. In summary, our work overcame two major obstacles in DFO-based cancer treatment through a simple liposome-based drug delivery system. This nanoencapsulation and targeting paradigm lays the foundation for future application of iron chelation in cancer therapy.