Mesoporous nanodrug delivery system: a powerful tool for a new paradigm of remodeling of the tumor microenvironment.

Tumor microenvironment (TME) plays an important role in tumor progression, metastasis and therapy resistance. Remodeling the TME has recently been deemed an attractive tumor therapeutic strategy. Due to its complexity and heterogeneity, remodeling the TME still faces great challenges. With the great advantage of drug loading ability, tumor accumulation, multifactor controllability, and persistent guest molecule release ability, mesoporous nanodrug delivery systems (MNDDSs) have been widely used as effective antitumor drug delivery tools as well as remolding TME. This review summarizes the components and characteristics of the TME, as well as the crosstalk between the TME and cancer cells and focuses on the important role of drug delivery strategies based on MNDDSs in targeted remodeling TME metabolic and synergistic anticancer therapy.

Iron metabolism: State of the art in hypoxic cancer cell biology.

The tumor microenvironment (TME) promotes the malignant transformation of cancer cells, mainly through metabolic reprogramming. As one of the most prominent features of the TME, hypoxia contributes to cancer cell death resistance, invasion, metastasis, and therapy-resistant phenotypes. As an important cofactor for various enzymes, iron is essential for ATP generation, antioxidant protein function, and DNA-damage repair in hypoxic cancer cells. Iron metabolism, as a promoter of aggressive hypoxic cancer cell biology, has attracted an increasing amount of attention. Iron utilization, storage, and efflux are enhanced in hypoxic cancer cells, which further contributes to cancer cell proliferation, metastasis, ferroptosis resistance, and immune escape. This review describes the relationship between iron metabolism and proliferation, metastasis, and ferroptosis of hypoxic cancer cells, as well as several iron-targeted cancer therapy strategies. Understanding the hypoxia-specific regulatory mechanism of iron metabolism could aid the development of targeted therapy against refractory hypoxic cancer cells.

O-GlcNAcylation of ZEB1 facilitated mesenchymal pancreatic cancer cell ferroptosis.

Background: Mesenchymal cancer cells, resistant to the traditional regulated cell death, are exquisitely vulnerable to ferroptosis. However, the underlying mechanism has been rarely studied. While glycolipid metabolism rewiring is a critical determination of both cancer cell mesenchymal phenotype and cell death resistance, we are interested in the underlying cross talk between glycolipid metabolism and mesenchymal cancer cell ferroptosis sensitivity. Methods: CCK-8, western blot and clone forming assay were used to access the effect of glucose on mesenchymal cancer cell ferroptosis susceptibility and O-GlcNAcylation level. GEPIA database, shRNA knockdown and various pharmacological inhibitors were used to analyze the relationship between O-GlcNAcylation and mesenchymal cancer cell ferroptosis in vitro and in vivo. A series of experiments were conducted to investigate the underlying mechanisms of glucose induced ZEB1 O-GlcNAcylation on mesenchymal cancer cell ferroptosis susceptibility. Results: Mesenchymal pancreatic cancer cells O-GlcNAcylation level and ferroptosis cell death was significantly increased under high glucose condition in vitro and in vivo. O-GlcNAcylation of ZEB1, rather than other transcription factors, was involved in this process. Mechanistically, glucose triggered ZEB1 O-GlcNAcylation at Ser555 site enhanced its stabilization and nuclear translocation, induced lipogenesis associated genes, FASN and FADS2, transcription activity, which ultimately resulted in lipid peroxidation dependent mesenchymal pancreatic cancer cell ferroptosis. Conclusions: These results identify a novel role of glycolipid metabolism and O-GlcNAcylation in mesenchymal cancer cells ferroptosis susceptibility, which broaden the molecular mechanism of ferroptosis and suggested a potential clinical therapeutic strategy for refractory tumors.

Branched-chain amino acid aminotransferase 2 regulates ferroptotic cell death in cancer cells.

Ferroptosis, a form of iron-dependent cell death driven by cellular metabolism and iron-dependent lipid peroxidation, has been implicated as a tumor-suppressor function for cancer therapy. Recent advance revealed that the sensitivity to ferroptosis is tightly linked to numerous biological processes, including metabolism of amino acid and the biosynthesis of glutathione. Here, by using a high-throughput CRISPR/Cas9-based genetic screen in HepG2 hepatocellular carcinoma cells to search for metabolic proteins inhibiting ferroptosis, we identified a branched-chain amino acid aminotransferase 2 (BCAT2) as a novel suppressor of ferroptosis. Mechanistically, ferroptosis inducers (erastin, sorafenib, and sulfasalazine) activated AMPK/SREBP1 signaling pathway through iron-dependent ferritinophagy, which in turn inhibited BCAT2 transcription. We further confirmed that BCAT2 as the key enzyme mediating the metabolism of sulfur amino acid, regulated intracellular glutamate level, whose activation by ectopic expression specifically antagonize system Xc- inhibition and protected liver and pancreatic cancer cells from ferroptosis in vitro and in vivo. On the contrary, direct inhibition of BCAT2 by RNA interference, or indirect inhibition by blocking system Xc- activity, triggers ferroptosis. Finally, our results demonstrate the synergistic effect of sorafenib and sulfasalazine in downregulating BCAT2 expression and dictating ferroptotic death, where BCAT2 can also be used to predict the responsiveness of cancer cells to ferroptosis-inducing therapies. Collectively, these findings identify a novel role of BCAT2 in ferroptosis, suggesting a potential therapeutic strategy for overcoming sorafenib resistance.

Soft Mesoporous Organosilica Nanoplatforms Improve Blood Circulation, Tumor Accumulation/Penetration, and Photodynamic Efficacy.

To date, the ability of nanoplatforms to achieve excellent therapeutic responses is hindered by short blood circulation and limited tumor accumulation/penetration. Herein, a soft mesoporous organosilica nanoplatform modified with hyaluronic acid and cyanine 5.5 are prepared, denoted SMONs-HA-Cy5.5, and comparative studies between SMONs-HA-Cy5.5 (24.2 MPa) and stiff counterparts (79.2 MPa) are conducted. Results indicate that, apart from exhibiting a twofold increase in tumor cellular uptake, the soft nanoplatforms also display a remarkable pharmacokinetic advantage, resulting in considerably improved tumor accumulation. Moreover, SMONs-HA-Cy5.5 exhibits a significantly higher tumor penetration, achieving 30-µm deeper tissue permeability in multicellular spheroids relative to the stiff counterparts. Results further reveal that the soft nanoplatforms have an easier extravasation from the tumor vessels, diffuse farther in the dense extracellular matrix, and reach deeper tumor tissues compared to the stiff ones. Specifically, the soft nanoplatforms generate a 16-fold improvement (43 vs. 2.72 µm) in diffusion distance in tumor parenchyma. Based on the significantly improved blood circulation and tumor accumulation/penetration, a soft therapeutic nanoplatform is constructed by loading photosensitizer chlorin e6 in SMONs-HA-Cy5.5. The resulting nanoplatform exhibits considerably higher therapeutic efficacy on tumors compared to the stiff ones.

Pifithrin-µ incorporated in gold nanoparticle amplifies pro-apoptotic unfolded protein response cascades to potentiate synergistic glioblastoma therapy.

Conventional radiotherapy has a pivotal role in the treatment of glioblastoma; nevertheless, its clinical utility has been limited by radiation resistance. There is emerging evidence that upregulated heat shock protein A5 (HSPA5) in cancer cells maintains or restores the homeostasis of a cellular microenvironment and results in cancer resistance in various treatments. Therefore, we describe a bioresponsive nanoplatform that can deliver a HSPA5 inhibitor (pifithrin-µ, PES) and radiosensitizer (gold nanosphere, AuNS), to expand the synergistic photothermal therapy and radiotherapy, as well as to monitor the progression of cancer therapy using computer tomography/magnetic resonance imaging. The nanoplatform (PES-Au@PDA, 63.3 ± 3.1 nm) comprises AuNS coated with the photothermal conversion agent polydopamine (PDA) for enhanced radiotherapy and photothermal therapy, as well as PES (loading efficiency of PES approximately 40%), a small molecular inhibitor against HSPA5 to amplify the pro-apoptotic unfolded protein response (UPR). The reported nanoplatform enables hyperthermia-responsive release of PES. Results from in vitro and in vivo studies demonstrate that PES-Au@PDA can specially activate pro-apoptotic UPR cascades, leading to remarkably improved radiotherapy and photothermal therapy efficiencies. Considered together, a versatile theranostic nanosystem is reported for promoting the synergistic radiophotothermal therapy by selectively activating pro-apoptotic UPR cascade pathways.

Orderly Curled Silica Nanosheets with a Small Size and Macromolecular Loading Pores: Synthesis and Delivery of Macromolecules To Eradicate Drug-Resistant Cancer.

Hierarchically organized silica nanomaterials have shown great promise for nanomedicine. However, the synthesis of silica nanomaterials with a small size and macromolecular loading pore is still a big challenge. Herein, orderly curled silica nanosheets (OCSNs) with a ∼42 nm diameter and orderly connected large channels (∼13.4 nm) were successfully prepared for the first time. The key to the formation of the unique structure (OCSNs) is using an oil/water reaction system with high concentrations of the surfactant and alkali. The prepared OCSNs exhibit a long blood circulation halftime (0.97 h) and low internalization in the reticuloendothelial system. Notably, the large superficial channels can concurrently house large guest molecules (siRNA) and chemotherapeutic drugs. Furthermore, drug-loaded OCSNs modified with polyglutamic acids can greatly increase the accumulation of incorporated siRNA and doxorubicin in solid tumors and restrain the growth of drug-resistant orthotopic breast cancer by inducing cell apoptosis. Overall, we report the preparation of hierarchically OCSNs; their small size and macromolecular loading pores are very promising for the delivery of large guest molecules and chemotherapeutic drugs for cancer therapy.

Role of GRP78 inhibiting artesunate-induced ferroptosis in KRAS mutant pancreatic cancer cells.

Objective: To investigate the exact role of GRP78 in artesunate-induced ferroptosis in KRAS mutant pancreatic cancer cells. Methods: Artesunate-induced KRAS mutant human pancreatic cancer cells (AsPC-1 and PaTU8988) ferroptosis was confirmed by fluorescent staining experiments and CCK8. Western blot and short-hairpin RNA-based knockdown assays were conducted to detect GRP78 activity and its role in artesunate-induced ferroptosis. Results: Artesunate induced AsPC-1 and PaTU8988 cell death in ferroptosis manner, rather than necrosis or apoptosis. In addition, artesunate increased the mRNA and protein levels of GRP78 in a concentration-dependent manner in AsPC-1 and PaTU8988 cells. Knockdown GRP78 enhanced artesunate-induced ferroptosis of pancreatic cancer cells in vitro and in vivo. Conclusion: Combining artesunate with GRP78 inhibition may be a novel maneuver for effective killing of KRAS mutant pancreatic ductal adenocarcinoma cells.

Soft mesoporous organosilica nanorods with gold plasmonic core for significantly enhanced cellular uptake.

Soft nanoparticles have attracted increasing attention in biomedical fields because of their unique biological behaviors such as long circulation and high cellular uptake. However, previously reported soft nanoparticles are generally spherical or torispherical in shape, and non-spherical soft nanoparticles are rarely reported because of the shape is thermodynamically unstable for typical soft materials (e.g., liposomes and micelles). Herein, soft mesoporous organosilica nanorods with gold plasmonic core protected with poly-ethylene imine (GNR@SMON/PEI) have been successfully synthesized, for the first time, by a dispersive-protection etching method, in which rod-like solid mesoporous organosilicas with gold nanorod are firstly shielded with PEI (GNR@MON/PEI) and then etched with aqueous NaOH solution. The prepared GNR@SMON/PEI inherits the rod morphology of the mother particle, showing wrinkled morphology and excellent dispersity thanks to the dispersive-protection effect of PEI. In addition, the GNR@SMON/PEI possesses a uniform size (174 × 105 nm), well-defined mesopores (3.9 nm), high surface area (355 m2/g) and large pore volume (0.35 m3/g). Notably, the soft GNR@SMON/PEI exhibits significantly lower Young's modulus (120.2 MPa) in contrast with the hard counterpart (361.4 MPa). Furthermore, after being decorated with hyaluronic acid (HA), the soft GNR@SMON/PEI-HA exhibits excellent in vitro and in vivo biocompatibility. The soft GNR@SMON/PEI-HA has achieved 3-fold cellular uptake efficiency in contrast with the hard one, indicating great potential for biomedical applications. Taken together, this work reports the controllable synthesis of a soft mesoporous nanorod with high cellular uptake efficiency, providing a vital strategy for the synthesis of non-spherical soft nanoparticles and a new nanoplatform for various biomedical applications in future.

Sensitive, Real-Time, and In-Vivo Oxygen Monitoring for Photodynamic Therapy by Multifunctional Mesoporous Nanosensors.

Real-time monitoring of oxygen consumption is beneficial to predict treatment responses and optimize therapeutic protocols for photodynamic therapy (PDT). In this work, we first demonstrate that deformable hollow mesoporous organosilica nanoparticles (HMONs) can be used to load [(Ru(dpp)3)]Cl2 for detecting oxygen (denoted as HMON-[(Ru(dpp)3)]Cl2). This nanoprobe shows significantly improved biocompatibility and high cellular uptake. In-vitro experiments demonstrate that the HMON-[(Ru(dpp)3)]Cl2 can sensitively detect oxygen changes between 1% and 20%. On this basis, photosensitizer chlorin e6 (Ce6) and [(Ru(dpp)3)]Cl2 are simultaneously loaded in the HMONs (denoted as HMON-Ce6-[(Ru(dpp)3)]Cl2) for real-time oxygen monitoring during photodynamic therapy. The HMON-Ce6-[(Ru(dpp)3)]Cl2 can reflects oxygen consumption in solution and cells in photodynamic therapy. Furthermore, the ability of the HMON-Ce6-[(Ru(dpp)3)]Cl2 nanosensor to monitor oxygen changes is demonstrated in tumor-bearing nude mice.

Radiotherapy-induced cell death activates paracrine HMGB1-TLR2 signaling and accelerates pancreatic carcinoma metastasis.

BACKGROUND: Dying cells after irradiation could promote the repopulation of surviving cancer cells leading to tumor recurrence. We aim to define the role of dying cells in promoting pancreatic cancer cells metastasis following radiotherapy. METHODS: Using the transwell system as the in vitro co-culture model, a small number of untreated pancreatic cancer cells were seeded in the upper chamber, while a larger number of lethally treated pancreatic cancer cells were seeded in the lower chamber. A series of experiments were conducted to investigate the role of dying-cell-derived HMGB1 on the invasion of pancreatic cancer in vitro and cancer metastasis in vivo. We then designed shRNA knockdown and Western blot assays to detect signaling activity. RESULTS: We found that dying pancreatic cancer cells significantly promote the invasion of pancreatic cancer cells in vitro and cancer metastasis in vivo. HMGB1 gene knockdown attenuated the migration-stimulating effect of irradiated, dying cells on living pancreatic cancer cells. Finally, we showed that dying-cell-derived HMGB1 functions in a paracrine manner to affect cancer-cell migration dependent on acquiring an epithelial-mesenchymal transition (EMT) phenotype and PI3K/pAkt activation. This process is mediated by the receptor for TLR2. CONCLUSION: Our study indicates that, during radiotherapy, dying pancreatic cancer cells activate paracrine signaling events that promote the mobility of surviving tumor cells. We suggest a strategy to inhibit HMGB1 for preventing pancreatic carcinoma relapse and metastasis.