Inhibition of CaMKIIα Activity Enhances Antitumor Effect of Fullerene C60 Nanocrystals by Suppression of Autophagic Degradation

Construction of a Multifunctional Upconversion Nanoplatform Based on Autophagy Inhibition and Photodynamic Therapy Combined with Chemotherapy for Antitumor Therapy

Inhibition of autophagy increases the sensitivity of tumor cells to radiotherapy and chemotherapy and improves the therapeutic effect on tumors. Recently, photodynamic therapy (PDT) combined with chemotherapy has been proven to further improve the efficiency of cancer treatment. As such, combining autophagy inhibition with PDT and chemotherapy may represent a potentially effective new strategy for cancer treatment. However, currently widely studied autophagy inhibitors inevitably produce various toxic side effects due to their inherent pharmacological activity. To overcome this constraint, in this study, we designed an ideal multifunctional upconversion nanoplatform, UCNP-Ce6-EPI@mPPA + NIR (MUCEN). Control, UCNP-EPI@mPPA (MUE), UCNP-EPI@mPPA + NIR (MUEN), Ce6-EPI@mPPA (MCE), Ce6-EPI@mPPA + NIR (MCEN), and UCNP-Ce6-EPI@mPPA (MUCE) groups were set up separately as controls. Based on a combination of autophagy inhibition and PDT, the average particle size of MUCEN was 197 nm, which can simultaneously achieve the double encapsulation of chlorine e6 (Ce6) and epirubicin (EPI). In vitro tests revealed that MUCE was efficiently endocytosed by 4T1 cells under near-infrared light irradiation. Further, in vivo tests revealed that MUCE dramatically inhibited tumor growth. Immunohistochemistry results indicated that MUCE efficiently increased the expression of autophagy inhibitors p62 and LC3 in tumor tissues. The synergistic effect of autophagy inhibition and PDT with MUCE exhibited superior tumor suppression, providing an innovative approach to cancer treatment.

Dihydroartemisinin alleviates doxorubicin-induced cardiotoxicity and ferroptosis by activating Nrf2 and regulating autophagy

Although the use of Doxorubicin (Dox) is extensive in the treatment of malignant tumor, the toxic effects of Dox on the heart can cause myocardial injury. Therefore, it is necessary to find an alternative drug to alleviate the Dox-induced cardiotoxicity. Dihydroartemisinin (DHA) is a semisynthetic derivative of artemisinin, which is an active ingredient of Artemisia annua. The study investigates the effects of DHA on doxorubicin-induced cardiotoxicity and ferroptosis, which are related to the activation of Nrf2 and the regulation of autophagy. Different concentrations of DHA were administered by gavage for 4 weeks in mice. H9c2 cells were pretreated with different concentrations of DHA for 24 h in vitro. The mechanism of DHA treatment was explored through echocardiography, biochemical analysis, real-time quantitative PCR, western blotting analysis, ROS/DHE staining, immunohistochemistry, and immunofluorescence. In vivo, DHA markedly relieved Dox-induced cardiac dysfunction, attenuated oxidative stress, alleviated cardiomyocyte ferroptosis, activated Nrf2, promoted autophagy, and improved the function of lysosomes. In vitro, DHA attenuated oxidative stress and cardiomyocyte ferroptosis, activated Nrf2, promoted clearance of autophagosomes, and reduced lysosomal destruction. The changes of ferroptosis and Nrf2 depend on selective degradation of keap1 and recovery of lysosome. We found for the first time that DHA could protect the heart from the toxic effects of Dox-induced cardiotoxicity. In addition, DHA significantly alleviates Dox-induced ferroptosis through the clearance of autophagosomes, including the selective degradation of keap1 and the recovery of lysosomes.

Osteosarcoma-targeted Cu and Ce based oxide nanoplatform for NIR II fluorescence/magnetic resonance dual-mode imaging and ros cascade amplification along with immunotherapy

BACKGROUND

As the lethal bone tumor, osteosarcoma often frequently occurs in children and adolescents with locally destructive and high metastasis. Distinctive kinds of nanoplatform with high therapeutical effect and precise diagnosis for osteosarcoma are urgently required. Multimodal optical imaging and programmed treatment, including synergistic photothermal-chemodynamic therapy (PTT-CDT) elicits immunogenetic cell death (ICD) is a promising strategy that possesses high bio-imaging sensitivity for accurate osteosarcoma delineating as well as appreciable therapeutic efficacy with ignorable side-effects.

METHODS AND RESULTS

In this study, mesoporous Cu and Ce based oxide nanoplatform with Arg-Gly-Asp (RGD) anchoring is designed and successfully constructed. After loading with indocyanine green, this nanoplatform can be utilized for precisely targeting and efficaciously ablating against osteosarcoma via PTT boosted CDT and the closely following ICD stimulation both in vitro and in vivo. Besides, it provides off-peak fluorescence bio-imaging in the second window of near-infrared region (NIR II, 1000-1700 nm) and Magnetic resonance signal, serves as the dual-mode contrast agents for osteosarcoma tissue discrimination.

CONCLUSION

Tumor targeted Cu&Ce based mesoporous nanoplatform permits efficient osteosarcoma suppression and dual-mode bio-imaging that opens new possibility for effectively diagnosing and inhibiting the clinical malignant osteosarcoma.

Nanoplatform-Mediated Autophagy Regulation and Combined Anti-Tumor Therapy for Resistant Tumors

The overall cancer incidence and death toll have been increasing worldwide. However, the conventional therapies have some obvious limitations, such as non-specific targeting, systemic toxic effects, especially the multidrug resistance (MDR) of tumors, in which, autophagy plays a vital role. Therefore, there is an urgent need for new treatments to reduce adverse reactions, improve the treatment efficacy and expand their therapeutic indications more effectively and accurately. Combination therapy based on autophagy regulators is a very feasible and important method to overcome tumor resistance and sensitize anti-tumor drugs. However, the less improved efficacy, more systemic toxicity and other problems limit its clinical application. Nanotechnology provides a good way to overcome this limitation. Co-delivery of autophagy regulators combined with anti-tumor drugs through nanoplatforms provides a good therapeutic strategy for the treatment of tumors, especially drug-resistant tumors. Notably, the nanomaterials with autophagy regulatory properties have broad therapeutic prospects as carrier platforms, especially in adjuvant therapy. However, further research is still necessary to overcome the difficulties such as the safety, biocompatibility, and side effects of nanomedicine. In addition, clinical research is also indispensable to confirm its application in tumor treatment.

Vitamin C enhances the sensitivity of osteosarcoma to arsenic trioxide via inhibiting aerobic glycolysis

Osteosarcoma (OS) is a common malignant tumor disease in the department of orthopedics, which is prone to the age of adolescents and children under 20 years old. Arsenic trioxide (ATO), an ancient poison, has been reported to play a critical role in a variety of tumor treatments, including OS. However, due to certain poisonous side effects such as cardiotoxicity and hepatotoxicity, clinical application of ATO has been greatly limited. Here we report that low doses of ATO (1 μM) observably reduced the half-effective inhibitory concentration (IC50) of vitamin C on OS cells. Compared with the treatment alone, the synthetic application of vitamin C (VitC, 800 μM) and ATO (1 μM) significantly further inhibited the proliferation, migration, and invasion of OS cells and promoted cell apoptosis in vitro. Meanwhile, we observed that the combined application of VitC and ATO directly suppresses the aerobic glycolysis of OS cells with the decreased production of pyruvate, lactate, and ATP via inhibiting the expression of the critical glycolytic genes (PGK1, PGM1, and LDHA). Moreover, the combination of VitC (200 mg/kg) and ATO (1 mg/kg) with tail vein injection significantly delayed OS growth and migration of nude mice by inhibiting aerobic glycolysis of OS. Thus, our results demonstrate that VitC effectively increases the sensitivity of OS to low concentrations of ATO via inhibiting aerobic glycolysis to alleviate the toxic side effects of high doses of arsenic trioxide, suggesting that synthetic application of VitC and ATO is a promising approach for the clinical treatment of human OS.

A biodegradable hollow nanoagent enables a boosted chemodynamic therapy by simultaneous autophagy inhibition and macrophage reeducation

Various therapeutic strategies, including chemotherapy, radiotherapy, photothermal therapy (PTT), and immunotherapy have been applied in cancer therapy. However, intrinsic or acquired therapeutic resistance is the main obstacle that attenuates the treatment effect of the therapeutic reagents used in these strategies. Studies have shown that autophagy and immunosuppressive tumor-associated macrophages (TAMs), as internal and external resistance mechanisms, would significantly compromise the effectiveness of cancer treatment. Therefore, selectively blocking the autophagy and repolarizing TAMs to anti-tumor phenotype (M1) will be effective for cancer treatments. Herein, an ambidextrous strategy that simultaneously inhibited autophagy and reeducated TAMs to promote anti-tumor therapy meditated by the iron-based nanocarriers was reported. The released Fe (II) ion reacted with the released artemisinin (ART) to produce ROS for chemodynamic therapy (CDT). The chloroquine (CQ) was used to inhibit autophagy in cancer cells and reset TAMs from the M2 phenotype to the M1 phenotype, eliminating the resistance of cancer cells and realizing an augmented therapeutic effect. This work provides a promising way for augmenting therapeutic efficiency by simultaneously interfering with two critical therapeutic resistance mechanisms.

Advances in tumor nanotechnology: theragnostic implications in tumors via targeting regulated cell death

Cell death constitutes an indispensable part of the organismal balance in the human body. Generally, cell death includes regulated cell death (RCD) and accidental cell death (ACD), reflecting the intricately molecule-dependent process and the uncontrolled response, respectively. Furthermore, diverse RCD pathways correlate with multiple diseases, such as tumors and neurodegenerative diseases. Meanwhile, with the development of precision medicine, novel nano-based materials have gradually been applied in the clinical diagnosis and treatment of tumor patients. As the carrier, organic, inorganic, and biomimetic nanomaterials could facilitate the distribution, improve solubility and bioavailability, enhance biocompatibility and decrease the toxicity of drugs in the body, therefore, benefiting tumor patients with better survival outcomes and quality of life. In terms of the most studied cell death pathways, such as apoptosis, necroptosis, and pyroptosis, plenty of studies have explored specific types of nanomaterials targeting the molecules and signals in these pathways. However, no attempt was made to display diverse nanomaterials targeting different RCD pathways comprehensively. In this review, we elaborate on the potential mechanisms of RCD, including intrinsic and extrinsic apoptosis, necroptosis, ferroptosis, pyroptosis, autophagy-dependent cell death, and other cell death pathways together with corresponding nanomaterials. The thorough presentation of RCD pathways and diverse nano-based materials may provide a wider cellular and molecular landscape of tumor diagnosis and treatments.

Mesopore-encaged active MnOx in nano-silica selectively suppresses lung cancer cells by inducing autophagy

Autophagy induced by nanomaterials is one of the intracellular catabolic pathways that degrade and recycle the biomacromolecules and damaged organelles in cells and has emerged as a very promising pharmacological target critical to future drug development and anti-cancer therapy. Herein, we developed mesopore-encaged highly-dispersed active cluster-like MnOx in nanosilica entitled MnO-MS, with a size of around 130 nm. Our studies show that MnO-MS could not only obviously induce autophagy in both stable GFP-LC3 HeLa cells and GFP-LC3-mCherry HeLa cells but also could selectively inhibit lung cancer A549 cell growth at 11.19 μg mL^-1 (IC₅₀) while exhibiting little cytotoxicity in normal cells. Encouraged by these interesting results, a further mechanistic study reveals that reactive oxygen species (ROS) were excited by the active MnOx in nanosilica, leading to the disruption of mitochondrial membrane potential (MMP), enhancement of ATG5A/ATG16L/ATG4B/Beclin1, and finally, inhibition of the mTOR signaling pathways. Collectively, these findings indicate that MnO-MS-induced cell death via autophagy pathways in cancer cells. Furthermore, MnO-MS significantly inhibited tumor growth with minimal side effects in vivo, and it is envisioned that MnO-MS can be further developed as a potential autophagy inducer for the treatment of lung cancers.

Inhibition of phosphorylated calcium/calmodulin-dependent protein kinase IIα relieves streptozotocin-induced diabetic neuropathic pain through regulation of P2X3 receptor in dorsal root ganglia

Diabetic neuropathic pain (DNP) is frequent among patients with diabetes. We previously showed that P2X3 upregulation in dorsal root ganglia (DRG) plays a role in streptozotocin (STZ)-induced DNP but the underlying mechanism is unclear. Here, a rat model of DNP was established by a single injection of STZ (65 mg/kg). Fasting blood glucose was significantly elevated from the 1^st to 3^rd week. Paw withdrawal thresholds (PWTs) and paw withdrawal latencies (PWLs) in diabetic rats significantly reduced from the 2^nd to 3^rd week. Western blot analysis revealed that elevated p-CaMKIIα levels in the DRG of DNP rats were accompanied by pain-associated behaviors while CaMKIIα levels were unchanged. Immunofluorescence revealed significant increase in the proportion of p-CaMKIIα immune positive DRG neurons (stained with NeuN) in the 2^nd and 3^rd week and p-CaMKIIα was co-expressed with P2X3 in DNP rats. KN93, a CaMKII antagonist, significantly reduce mechanical hyperalgesia and thermal hyperalgesia and these effects varied dose-dependently, and suppressed p-CaMKIIα and P2X3 upregulation in the DRGs of DNP rats. These results revealed that the p-CaMKIIα upregulation in DRG is involved in DNP, which possibly mediated P2X3 upregulation, indicating CaMKIIα may be an effective pharmacological target for DNP management.

Reductive damage induced autophagy inhibition for tumor therapy

Numerous therapeutic anti-tumor strategies have been developed in recent decades. However, their therapeutic efficacy is reduced by the intrinsic protective autophagy of tumors. Autophagy plays a key role in tumorigenesis and tumor treatment, in which the overproduction of reactive oxygen species (ROS) is recognized as the direct cause of protective autophagy. Only a few molecules have been employed as autophagy inhibitors in tumor therapy to reduce protective autophagy. Among them, hydroxychloroquine is the most commonly used autophagy inhibitor in clinics, but it is severely limited by its high therapeutic dose, significant toxicity, poor reversal efficacy, and nonspecific action. Herein, we demonstrate a reductive-damage strategy to enable tumor therapy by the inhibition of protective autophagy via the catalytic scavenging of ROS using porous nanorods of ceria (PN-CeO2) nanozymes as autophagy inhibitor. The antineoplastic effects of PN-CeO2 were mediated by its high reductive activity for intratumoral ROS degradation, thereby inhibiting protective autophagy and activating apoptosis by suppressing the activities of phosphatidylinositide 3-kinase/protein kinase B and p38 mitogen-activated protein kinase pathways in human cutaneous squamous cell carcinoma. Further investigation highlighted PN-CeO2 as a safe and efficient anti-tumor autophagy inhibitor. Overall, this study presents a reductive-damage strategy as a promising anti-tumor approach that catalytically inhibits autophagy and activates the intrinsic antioxidant pathways of tumor cells and also shows its potential for the therapy of other autophagy-related diseases.

Electronic Supplementary Material

Supplementary material (cellular uptake of PN-CeO2, effects of PN-CeO2 on several common malignant tumor models, viability of HaCaT cells treated with PN-CeO2 at different concentrations, time-dependent body-weight curves of SCL-1 tumor-bearing nude mice, the biodistribution of Ce element in main tissues and tumors after injection of PN-CeO2, measurement of Ce element concentration in urine and feces samples, H&E-stained images of main organs, and measurement of liver and kidney function in mice after different treatment) is available in the online version of this article at 10.1007/s12274-022-5139-z.

Development of a novel autophagy-related gene model for gastric cancer prognostic prediction

Gastric cancer (GC) is a major global health issue and one of the leading causes of tumor-associated mortality worldwide. Autophagy is thought to play a critical role in the development and progression of GC, and this process is controlled by a set of conserved regulators termed autophagy-related genes (ATGs). However, the complex contribution of autophagy to cancers is not completely understood. Accordingly, we aimed to develop a prognostic model based on the specific role of ATGs in GC to improve the prediction of GC outcomes. First, we screened 148 differentially expressed ATGs between GC and normal tissues in The Cancer Genome Atlas (TCGA) cohort. Consensus clustering in these ATGs was performed, and based on that, 343 patients were grouped into two clusters. According to Kaplan–Meier survival analysis, cluster C2 had a worse prognosis than cluster C1. Then, a disease risk model incorporating nine differentially expressed ATGs was constructed based on the least absolute shrinkage and selection operator (LASSO) regression analysis, and the ability of this model to stratify patients into high- and low-risk groups was verified. The predictive value of the model was confirmed using both training and validation cohorts. In addition, the results of functional enrichment analysis suggested that GC risk is correlated with immune status. Moreover, autophagy inhibition increased sensitivity to cisplatin and exacerbated reactive oxygen species accumulation in GC cell lines. Collectively, the results indicated that this novel constructed risk model is an effective and reliable tool for predicting GC outcomes and could help with individual treatment through ATG targeting.

LINC00173 regulates polycystic ovarian syndrome progression by promoting apoptosis and repressing proliferation in ovarian granulosa cells via the microRNA-124-3p (miR-124-3p)/jagged canonical Notch ligand 1 (JAG1) pathway

As an endocrine and metabolic disorder, polycystic ovarian syndrome (PCOS) is common in females at childbearing age. Our work was intended to uncover the underlying role of LINC00173 and its potential regulatory mechanism in PCOS based on two cell lines (PCOS granulosa cells and KGN cells) and an in vivo model established from Sprague Dawley rats. It was revealed that LINC00173 and JAG1 expressions were upregulated, while miR-124-3p was poorly expressed in PCOS patients and PCOS rats. Functional assays showed that LINC00173 overexpression repressed proliferation and stimulated apoptosis in granulosa cells and KGN cells, while LINC00173 downregulation exhibited the opposite effects. Besides, it was verified that LINC00173 upregulated JAG1 expression in KGN cells via competitively binding to miR-124-3p. Similarly, miR-124-3p abundance was inversely related to LINC00173 and JAG1 level in PCOS. Subsequently, rescue assays elucidated that miR-124-3p upregulation or downregulation eliminated the effects on KGN cell proliferation and apoptosis mediated by LINC00173 overexpression or knockdown. In addition, it was found that the JAG1 level in KGN cells was adversely modulated by miR-124-3p and positively modulated by LINC00173. Moreover, it was further demonstrated that the reduced cell vitality and increased apoptosis of KGN cells induced by overexpressing LINC00173 could be relieved by JAG1 deletion. These findings suggested that LINC00173 could be a latent regulating factor for PCOS progression via modulating the miR-124-3p/JAG1 cascade.

Research Progress and Prospects of Autophagy in the Mechanism of Multidrug Resistance in Tumors

Although the treatment of cancer has made great strides in clinical practice, its high morbidity and fatality rates remain a major threat to human health. Multidrug resistance (MDR) often appears in the process of tumor treatment, leading to tumor refractory and aggravating the risk of tumor recurrence. Therefore, antitumor MDR plays a key role in tumor chemotherapy. Autophagy is an important process for the turnover of intracellular materials, which is commonly seen in the treatment of sensitive and multidrug-resistant tumors, and it can play different roles in various types of MDR tumor cells and tissues. Autophagy plays a dual regulatory role in MDR tumors. On the one hand, autophagy can promote the formation of MDR in tumor cells, weaken the killing effect of chemotherapy drugs on tumor cells, and play a protective role in tumor survival. On the other hand, autophagy production in the cellular environment can kill MDR tumor cells, reverse tumor resistance and enhance the efficiency of chemotherapy drugs. Therefore, the regulation of autophagy to overcome MDR has become increasingly significant in tumor chemotherapy. In this article, we discussed and summarized the research progress of autophagy in MDR tumors, mainly involving the different characteristics of autophagy in MDR cancer cells.

Sodium-Glucose Co-transporter-2 Inhibitor of Dapagliflozin Attenuates Myocardial Ischemia/Reperfusion Injury by Limiting NLRP3 Inflammasome Activation and Modulating Autophagy

Background: The sodium-glucose co-transporter-2 (SGLT-2) inhibitor dapagliflozin improves cardiovascular outcomes in patients with type 2 diabetes in a manner that is partially independent of its hypoglycemic effect. These observations suggest that it may exert a cardioprotective effect by another mechanism. This study explored the effects of dapagliflozin on myocardial ischemia/reperfusion injury in a mouse model. Materials and Methods: For the in vivo I/R studies, mice received 40 mg/kg/d dapagliflozin, starting 7 days before I/R. Evans Blue/TTC double-staining was used to determine the infarct size. Serum levels of cTnI, CK-MB, and LDH were measured. Inflammation, autophagy protein expression, and caspase-1 activity changes were measured at the protein level. Primary cardiomyocytes were used to investigate the direct effect of dapagliflozin on cardiomyocytes and to verify whether they have the same effect as observed in in vivo experiments. Result: A high dose of dapagliflozin significantly reduced infarct size and decreased the serum levels of cTnI, CK-MB, and LDH. Dapagliflozin also reduced serum levels of IL-1β, reduced expression of myocardial inflammation-related proteins, and inhibited cardiac caspase-1 activity. The treatment restored autophagy flux and promoted the degradation of autophagosomes. Relief of inflammation relied on autophagosome phagocytosis of NLRP3 and autophagosome clearance after lysosome improvement. 10 μM dapagliflozin reduced intracellular Ca²⁺ and Na⁺ in primary cardiomyocytes, and increasing NHE1 and NCX expression mitigated dapagliflozin effects on autophagy. Conclusion: Dapagliflozin protects against myocardial ischemia/reperfusion injury independently of its hypoglycemic effect. High-dose dapagliflozin pretreatment might limit NLRP3 inflammasome activation and mediate its selective autophagy. Dapagliflozin directly acts on cardiomyocytes through NHE1/NCX.

Peptide-based semiconducting polymer nanoparticles for osteosarcoma-targeted NIR-II fluorescence/NIR-I photoacoustic dual-model imaging and photothermal/photodynamic therapies

Background

The overall survival rate of osteosarcoma (OS) patients has not been improved for 30 years, and the diagnosis and treatment of OS is still a critical issue. To improve OS treatment and prognosis, novel kinds of theranostic modalities are required. Molecular optical imaging and phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), are promising strategies for cancer theranostics that exhibit high imaging sensitivity as well as favorable therapeutic efficacy with minimal side effect. In this study, semiconducting polymer nanoparticles (SPN-PT) for OS-targeted PTT/PDT are designed and prepared, using a semiconducting polymer (PCPDTBT), providing fluorescent emission in the second near-infrared window (NIR-II, 1000 - 1700 nm) and photoacoustic (PA) signal in the first near-infrared window (NIR-I, 650 - 900 nm), served as the photosensitizer, and a polyethylene glycolylated (PEGylated) peptide PT, providing targeting ability to OS.

Results

The results showed that SPN-PT nanoparticles significantly accelerated OS-specific cellular uptake and enhanced therapeutic efficiency of PTT and PDT effects in OS cell lines and xenograft mouse models. SPN-PT carried out significant anti-tumor activities against OS both in vitro and in vivo.

Conclusions

Peptide-based semiconducting polymer nanoparticles permit efficient NIR-II fluorescence/NIR-I PA dual-modal imaging and targeted PTT/PDT for OS.

Graphic Abstract

Effects of Metallic and Carbon-Based Nanomaterials on Human Pancreatic Cancer Cell Lines AsPC-1 and BxPC-3

Pancreatic cancer, due to its asymptomatic development and drug-resistance, is difficult to cure. As many metallic and carbon-based nanomaterials have shown anticancer properties, we decided to investigate their potential use as anticancer agents against human pancreatic adenocarcinoma. The objective of the study was to evaluate the toxic properties of the following nanomaterials: silver (Ag), gold (Au), platinum (Pt), graphene oxide (GO), diamond (ND), and fullerenol (C₆₀(OH)₄₀) against the cell lines BxPC-3, AsPC-1, HFFF-2, and HS-5. The potential cytotoxic properties were evaluated by the assessment of the cell morphology, cell viability, and cell membrane damage. The cancer cell responses to GO and ND were analysed by determination of changes in the levels of 40 different pro-inflammatory proteins. Our studies revealed that the highest cytotoxicity was obtained after the ND treatment. Moreover, BxPC-3 cells were more sensitive to ND than AsPC-1 cells due to the ND-induced ROS production. Furthermore, in both of the cancer cell lines, ND caused an increased level of IL-8 and a decreased level of TIMP-2, whereas GO caused only decreased levels of TIMP-2 and ICAM-1 proteins. This work provides important data on the toxicity of various nanoparticles against pancreatic adenocarcinoma cell lines.

TGF‑β inhibitor RepSox suppresses osteosarcoma via the JNK/Smad3 signaling pathway

Osteosarcoma (OS) is the most common malignant bone tumor and the long-term survival rates remain unsatisfactory. Transforming growth factor-β (TGF-β) has been revealed to play a crucial role in OS progression, and RepSox is an effective TGF-β inhibitor. In the present study, the effect of RepSox on the proliferation of the OS cell lines (HOS and 143B) was detected. The results revealed that RepSox effectively inhibited the proliferation of OS cells by inducing S-phase arrest and apoptosis. Moreover, the inhibitory effect of RepSox on cell migration and invasion was confirmed by wound-healing and Transwell assays. Furthermore, western blotting revealed that the protein levels of molecules associated with the epithelial-mesenchymal transition (EMT) phenotype, including E-cadherin, N-cadherin, Vimentin, matrix metalloproteinase (MMP)-2 and MMP-9, were reduced by RepSox treatment. Concurrently, it was also revealed that the JNK and Smad3 signaling pathway was inhibited. Our in vivo findings using a xenograft model also revealed that RepSox markedly inhibited the growth of tumors. In general, our data demonstrated that RepSox suppressed OS proliferation, EMT and promoted apoptosis by inhibiting the JNK/Smad3 signaling pathway. Thus, RepSox may be a potential anti-OS drug.

CAMK2/CaMKII activates MLKL in short-term starvation to facilitate autophagic flux

MLKL (mixed lineage kinase domain like pseudokinase) is a well-known core component of necrosome that executes necroptotic cell death upon phosphorylation by RIPK3 (receptor interacting serine/threonine kinase 3). Recent studies also implicate a role of MLKL in endosomal trafficking, which is not always dependent on RIPK3. Using mouse Neuro-2a and L929 as well as human HEK293 and HT29 cells, we show here that MLKL is phosphorylated in response to serum and amino acid deprivation from the culture medium, in a manner that depends on CAMK2/CaMKII (calcium/calmodulin dependent protein kinase II) but not RIPK3. The starvation-induced increase in MLKL phosphorylation was accompanied by decreases in levels of lipidated MAP1LC3B/LC3B (microtubule associated protein 1 light chain 3 beta; LC3-II) and SQSTM1/p62 (sequestosome 1), markers of autophagosomes. These changes were prevented by disrupting either MLKL or CAMK2 by pharmacology and genetic manipulations. Moreover, disrupting MLKL or CAMK2 also inhibited the incorporation of LC3-II into autolysosomes, demonstrating a role of the CAMK2-MLKL pathway in facilitating autophagic flux during short-term starvation, in contrast to necroptosis which suppressed autophagic flux. Furthermore, unlike the necroptotic pathway, the starvation-evoked CAMK2-mediated MLKL phosphorylation protected cells from starvation-induced death. We propose that upon nutrient deprivation, MLKL is activated by CAMK2, which in turn facilitates membrane scission needed for autophagosome maturation, allowing the proper fusion of the autophagosome with lysosome and the subsequent substance degradation. This novel function is independent of RIPK3 and is not involved in necroptosis, implicating new roles for this pseudokinase in cell survival, signaling and metabolism.

Abbreviations: CAMK2/CaMKII: calcium/calmodulin dependent protein kinase II; DIABLO/SMAC: direct inhibitor of apoptosis-binding protein with low pI/second mitochondria-derived activator of caspase; ECS: extracellular solution; ESCRT: endosomal sorting complexes required for transport; FBS: fetal bovine serum; GSK3B: glycogen synthase kinase 3 beta; HBSS: Hanks’ balanced salt solution; KO: knockout; LC3-II: lipidated microtubule associated protein 1 light chain 3 beta; LDH: lactate dehydrogenase; MLKL: mixed lineage kinase domain like pseudokinase; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; N2a: Neuro-2a neuroblastoma; Nec-1: necrostatin-1; NSA: necrosulfonamide; PBS: phosphate-buffered saline; PI: propidium iodide; PK-hLC3: pHluorin-mKate2-human LC3; RIPK1: receptor interacting serine/threonine kinase 1; RIPK3: receptor interacting serine/threonine kinase 3; ROS: reactive oxygen species; RPS6KB1/S6K: ribosomal protein S6 kinase B1; shRNA: short hairpin RNA; siRNA: small interference RNA; SQSTM1/p62: sequestosome 1; TBS: Tris-buffered saline; TNF/TNF-α: tumor necrosis factor; TSZ, treatment with TNF + DIABLO mimetics + z-VAD-FMK.

Piperlongumine inhibits the progression of osteosarcoma by downregulating the SOCS3/JAK2/STAT3 pathway via miR-30d-5p

AIMS

The present study evaluated the functions of Piperlongumine (PL) in osteosarcoma (OS) cell growth and metastasis both in vitro and in vivo.

MAIN METHODS

MTT assay was conducted to test the cytotoxic effects of PL on the human osteoblasts line HFOB1.19 and the human normal chondrocyte line C28/I2T. FITC-Annexin V and propidium iodide (PI) were used to examine cell apoptosis. The migration, invasion and relative epithelial-mesenchymal transition were examined by Transwell assay and Western blotting. Reverse transcription-quantitative PCR (RT-qPCR) was performed to analyze the cytokine signaling 3 (SOCS3) mRNA expression. TargetScan database was used to predict the target of SOCS3. The binding association between miR-30d-5p and SOCS3 in U2OS and MG63 cells was evaluated by the dual-luciferase reporter assay. A xenograft model was constructed to evaluate the effect of PL on OS cell growth in vivo.

KEY FINDINGS

The results revealed that PL inhibited the growth, migration, invasion, epithelial-mesenchymal transition, and promoted the apoptosis of OS cells dose-dependently. In addition, PL upregulated the protein levels of suppressor of SOCS3, while it inactivated the JAK2/STAT3 pathway, which was accompanied by a decreased level of microRNA (miR)-30d-5p. Furthermore, SOCS3was confirmed as a novel target of miR-30d-5p. Overexpression of miR-30d-5p not only led to decreased expression of SOCS3, but also dampened the antitumor effect of PL on OS.

SIGNIFICANCE

The present data demonstrated that PL inhibited the progression of OS via downregulation of the SOCS3-mediated JAK2/STAT3 pathway by inhibiting miR-30d-5p.

Ginsenoside Rg5 Inhibits Human Osteosarcoma Cell Proliferation and Induces Cell Apoptosis through PI3K/Akt/mTORC1-Related LC3 Autophagy Pathway

The function and mechanism underlying the suppression of human osteosarcoma cells by ginsenoside-Rg5 (Rg5) was investigated in the present study. MG-63, HOS, and U2OS cell proliferation was determined by MTT assay after Rg5 treatment for 24 h. Rg5 inhibited human osteosarcoma cell proliferation effectively in a dose-dependent manner. The range of effective inhibitory concentrations was 160-1280 nM. Annexin V-FITC and PI double-staining assay revealed that Rg5 induced human osteosarcoma cell apoptosis. Western blotting, qRT-PCR, and FACS experiments revealed that Rg5 inhibited human osteosarcoma cells via caspase-3 activity which was related to the LC3-mediated autophagy pathway. Rg5 decreased the phosphorylation of PI3K, Akt, and mTORC1 activation. In contrast, LC3-mediated autophagy and caspase-3 activity increased significantly. A PI3K/AKT stimulator, IGF-1, reversed Rg5-induced cell autophagy and apoptosis in MG-63 cells. Collectively, the current study demonstrated that Rg5 induced human osteosarcoma cell apoptosis through the LC3-mediated autophagy pathway. Under physiological conditions, activation of PI3K/AKT/mTORC1 inhibits LC3 activity and caspase-3-related cell apoptosis. However, Rg5 activated LC3 activity by inhibiting the activation of PI3K/AKT/mTORC1. The present study indicated that Rg5 could be a promising candidate as a chemotherapeutic agent against human osteosarcoma.

CXCR4 blockade sensitizes osteosarcoma to doxorubicin by inducing autophagic cell death via PI3K‑Akt‑mTOR pathway inhibition

Doxorubicin is one of the most frequently used chemotherapy drugs in the treatment of osteosarcoma (OS), but the emergence of chemoresistance often leads to treatment failure. C-X-C motif chemokine receptor 4 (CXCR4) has been demonstrated to regulate OS progression and metastasis. However, whether CXCR4 is also involved in OS chemoresistance and its molecular mechanisms has yet to be fully elucidated. In the present study, CXCR4-mediated autophagy for OS chemotherapy was investigated by western blot analysis, transmission electron microscopy and confocal microscopy. CXCR4 silencing enhanced doxorubicin-induced apoptosis by reducing P-glycoprotein in CXCR4⁺ LM8 cells, while CXCR4 overexpression promoted OS doxorubicin resistance in CXCR4⁻Dunn cells. Furthermore, CXCR4 silencing with or without doxorubicin increased the expression of beclin 1 and light chain 3B, and the number of autophagosomes and autolysosomes, as well as induced autophagic flux activation by suppressing the PI3K/AKT/mTOR signaling pathway. In addition, pretreatment with the autophagy inhibitor bafilomycin A1 attenuated CXCR4 abrogation-induced cell death. Finally, the CXCR4 antagonist AMD3100 synergistically reinforced the antitumor effect of doxorubicin in an orthotopic OS mouse model. Taken together, the present study revealed that CXCR4 inhibition sensitizes OS to doxorubicin by inducing autophagic cell death. Therefore, targeting the CXCR4/autophagy axis may be a promising therapeutic strategy to overcome OS chemotherapy resistance.

Fullerene C60 Protects Against Intestinal Injury from Deoxynivalenol Toxicity by Improving Antioxidant Capacity

Oxidative stress is involved in a wide variety of pathologies, and fullerene has been shown to have an antioxidant ability. Mycotoxins exert toxic effects through induction of excessive reactive oxygen species (ROS). Here, we evaluated water-soluble fullerene C60 for its anti-mycotoxin and antioxidant effects in vitro and in vivo. Intestinal epithelial cells were cultured with fullerene during deoxynivalenol (DON) exposure. The results revealed that fullerene C60 significantly promoted cell viability, decreased apoptosis and necrotic cell number, and significantly reduced intracellular ROS levels during DON exposure (p < 0.05). To investigate the role of fullerene in antioxidant capacity in vivo further, 40 three-week-old male C57BL/6 mice were randomly divided into four groups. There were no significant differences between the control and fullerene groups (p > 0.05). In mice exposed to DON, supplementation with fullerene C60 significantly improved growth performance, and enhanced the total antioxidant status and the activities of SOD and GPX in the intestine and liver (p < 0.05). In addition, fullerene C60 supplementation improved intestinal morphology, as indicated by a higher villus height and tight junction protein expression (p < 0.05). Furthermore, fullerene supplementation decreased serum concentrations of inflammatory cytokine and lipopolysaccharide (LPS; a penetrability marker) compared to the DON-challenged group (p < 0.05). The current study suggests that fullerene C60 improves intestinal antioxidant status against DON-induced oxidative stress in vitro and in vivo.

TRPV1 alleviates osteoarthritis by inhibiting M1 macrophage polarization via Ca2+/CaMKII/Nrf2 signaling pathway

Osteoarthritis (OA) is the major course of joint deterioration, in which M1 macrophage-driven synovitis exacerbates the pathological process. However, precise therapies for M1 macrophage to decrease synovitis and attenuate OA progression have been scarcely proposed. Transient receptor potential vanilloid 1 (TRPV1) is a cation channel that has been implicated in pain perception and inflammation. In this study, we investigated the role of TRPV1 in the M1 macrophage polarization and pathogenesis of OA. We demonstrated that TRPV1 expression and M1 macrophage infiltration were simultaneously increased in both human and rat OA synovium. More than 90% of the infiltrated M1 macrophages expressed TRPV1. In the rat OA model, intra-articular injection of capsaicin (CPS), a specific TRPV1 agonist, significantly attenuated OA phenotypes, including joint swelling, synovitis, cartilage damage, and osteophyte formation. CPS treatment markedly reduced M1 macrophage infiltration in the synovium. Further mechanistic analyses showed that TRPV1-evoked Ca2+ influx promoted the phosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII) and facilitated the nuclear localization of nuclear factor-erythroid 2-related factor 2 (Nrf2), which ultimately resulted in the inhibition of M1 macrophage polarization. Taken together, our findings establish that TRPV1 attenuates the progression of OA by inhibiting M1 macrophage polarization in synovium via the Ca2+/CaMKII/Nrf2 signaling pathway. These results highlight the effect of targeting TRPV1 for the development of a promising therapeutic strategy for OA.

microRNA-23 inhibits inflammation to alleviate rheumatoid arthritis via regulating CXCL12

Rheumatoid arthritis (RA) is a common systemic, inflammatory and autoimmune disorder. MicroRNAs (miRs) are strongly associated with the initiation and progression of RA. However, the functions and mechanisms underlying miR-23 in RA are not completely understood. Therefore, the present study aimed to investigate the molecular mechanisms underlying miR-23 in RA. A bioinformatics tool (StarBase) and a wide range of experimental assays, including reverse transcription-quantitative PCR, western blotting, luciferase reporter assays and ELISAs, were performed to investigate the biological role of miR-23 in RA. The results indicated that miR-23 was downregulated and chemokine C-X-C motif ligand 12 (CXCL12) was upregulated in RA samples compared with healthy samples. Furthermore, miR-23 overexpression suppressed inflammation via reducing TNF-α, IL-1β and IL-8 expression levels compared with the NC mimic group. Regarding the underlying mechanism, compared with NC mimic, miR-23 mimic decreased CXCL12 mRNA expression by binding to its 3'-untranslated region. Additionally, CXCL12 overexpression reversed miR-23 mimic-mediated effects on inflammation. NF-κB signaling is associated with inflammation. Therefore, the present study indicated that CXCL12 promoted inflammation by activating NF-κB signaling. In conclusion, miR-23 inhibited inflammation to alleviate RA by regulating CXCL12 via the NF-κB signaling pathway, which may serve as a potential target for the diagnosis and treatment of RA.

Expression of canonical transient receptor potential channels in U-2 OS and MNNG-HOS osteosarcoma cell lines

In U-2 OS and MNNG-HOS osteosarcoma cells, small interfering RNA-mediated knockdown of the angiotensin-(1-7) receptor, Mas, increases cell proliferation. Whether alterations in canonical transient receptor potential channels (TRPC) expression contribute to this effect is not clear. In the present study, a basic description of TRPC subtype expression in osteosarcoma cell lines was provided. The pharmacological modulators of the angiotensin-(1-7) receptor, Mas, AVE0991 (agonist), or D-Ala⁷-Ang-(1-7) (antagonist) were applied to elucidate a possible role of Mas in the regulation of TRPC mRNA levels. The contribution of other G-protein coupled receptors (GPCR) or receptor tyrosine kinases to TRCP expression was studied by applying the selective pharmacological blockers of either PI3 kinase or MEK/Erk1/2 signaling, Ly294002 and PD98059. AVE0991 and D-Ala⁷-Ang-(1-7) exhibited no or marginal effects on TRPC mRNA expression. Ly294002 provoked a 9.6- and 5.9-fold increase in the amounts of TRPC5 mRNA in MNNG-HOS and U-2 OS cells, respectively. Additionally, Ly294002 increased TRPC6 mRNA levels; however, it had no effect on TRPCs 1, 3 and 4. Administration of PD98059 increased the amounts of TRPC6 and TRPC4 ~2-fold. In conclusion, the present study demonstrated that Mas-dependent alterations in osteosarcoma cell line proliferation were not mediated by any changes in TRPC subtype gene expression. The data shows in principle, and consistent with the literature, that the signaling pathways examined can regulate the expression of TRPCs at the mRNA level. Therefore, direct and signaling pathway-specific pharmacological targeting of TRPC subtypes may represent an option for improving the treatment of osteosarcoma.

Synthesis, Characterization, Cellular Uptake, and In Vitro Anticancer Activity of Fullerenol-Doxorubicin Conjugates

Doxorubicin (DOX) is one of the most commonly used chemotherapeutic agents for treating human cancer. However, its clinical use has been limited by DOX-induced cardiotoxicity as well as other side effects. In the present study, we designed and synthesized the fullerenol (FU)-DOX conjugates and folic acid (FA)-grafted FU-DOX conjugates for improving the selectivity and activity of DOX in cancer cells. We further characterized the physicochemical properties and examined the release kinetics, cellular uptake, and in vitro anticancer activities of FU-DOX and FA-FU-DOX. The results showed that FU-DOX and FA-FU-DOX had a mean diameter of <200 nm and a low polydispersity. Both FU-DOX and FA-FU-DOX exhibited pH sensitivity and their DOX release rates were higher at pH 5.9 vs. pH 7.4. The cellular uptake studies indicated that FU conjugation enhanced the intracellular accumulation of DOX in human hepatocellular carcinoma (HCC) cell lines (BEL-7402 and HepG2) and the immortalized normal human hepatocytes (L02). The conjugation of FA to FU-DOX further promoted the drug internalization in an FR-dependent manner and enhanced the cytotoxicity against HCC cells. In conclusion, the newly prepared FA-FU-DOX conjugates can optimize the safety and efficacy profile of DOX.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

miR-4295 promotes cell proliferation, migration and invasion of osteosarcoma through targeting interferon regulatory factor 1

Osteosarcoma (OS) is the most common form of primary malignant bone tumor. Despite encouraging progress in the treatment of OS, the survival rate for patients with OS has remained unchanged over the past 40 years. It has been established that miRNA plays a crucial regulatory role in the progression and development of OS. To explore the potential association of miRNAs with OS, bioinformatics techniques were used to screen for differentially expressed miRNA genes in OS in the Gene Expression Omnibus database. In the GSE70367 database, it was revealed that miR-4295 expression was abnormally elevated in the expression of OS cells. To characterize the potential function of miR-4295 in OS, the expression levels of miR-4295 in 30 samples of OS and adjacent normal tissues was examined. The results revealed that the expression of miR-4295 was significantly increased in OS tissues compared with the paired normal tissues. Moreover, the expression levels of miR-4295 in OS cell lines (MG-63 and Saos-2) were significantly higher compared with those in the normal human mesenchymal stem cells. In addition, miR-4295 was associated with OS cell proliferation, migration and invasion. Furthermore, it was demonstrated that the expression of interferon regulatory factor (IRF)1, a tumor suppressor, was regulated by miR-4295 directly in OS cells. Taken together, the present results revealed that miR-4295 may act as a tumor activator by targeting IRF1 during the progression of OS. Investigating miR-4295 may provide novel insight into the mechanisms of OS metastasis, and inhibition and targeting miR-4295 may be a novel therapeutic strategy for the treatment of OS.

Oxyresveratrol induces apoptosis and inhibits cell viability via inhibition of the STAT3 signaling pathway in Saos‑2 cells

Oxyresveratrol (ORES) is a natural phenolic compound with multiple biological functions including antioxidation, anti-inflammation and neuroprotection; however, the inhibitory effect of ORES on osteosarcoma remains largely unknown. The present study aimed to determine the effects of ORES on osteosarcoma cell Saos-2. Cell Counting Kit-8 assay was performed to detect Soas-2 cell viability. Annexin-FITC/PI staining and JC-1 staining were used to measure cell apoptosis and the change of mitochondrial membrane potential. In addition, western blotting was conducted to determine the expression levels of apoptotic proteins and the phosphorylation of STAT3. It was found that ORES inhibited cell viability and induced apoptosis of osteosarcoma Saos-2 cells in a concentration-dependent manner. In addition, ORES increased the expression levels of apoptotic proteases caspase-9 and caspase-3 and reduced mitochondrial membrane potential. In response to ORES treatment, the expression levels of pro-apoptotic proteins, Bad and Bax, were enhanced, whereas those of anti-apoptotic proteins, Bcl-2 and Bcl-xL, were reduced. In addition, the phosphorylation of STAT3 was attenuated in Saos-2 cells after treatment with ORES. Inhibition of cell viability and apoptosis induction by ORES were rescued by enhancement of STAT3 activation upon treatment with IL-6. Collectively, the present study indicated that ORES induced apoptosis and inhibited cell viability, which may be associated with the inhibition of STAT3 activation; thus, ORES represents a promising agent for treating osteosarcoma.

circKMT2D contributes to H2O2-attenuated osteosarcoma progression via the miR-210/autophagy pathway

Circular RNAs (circRNAs) have been demonstrated to be involved in osteosarcoma (OS) development; however, the underlying mechanism of circKMT2D in OS progression remains unclear. The present study aimed to elucidate how circKMT2D could affect hydrogen peroxide (H₂O₂)-induced OS progression. H₂O₂ (100 µmol/l) was used to treat MG63 and U2OS cells. The cell viability, invasive ability, apoptosis and circKMT2D expression were detected using Cell Counting Kit-8 assay, Transwell assay, flow cytometry and reverse transcription-quantitative PCR, respectively. Furthermore, MG63 and U2OS cells transfected with circKMT2D short hairpin RNA and negative control were treated with H₂O₂, and circKMT2D expression and cell phenotype were determined. Dual-luciferase reporter assay was conducted to determine the association between circKMT2D and miR-210 expression level. Rescue experiments were conducted to examine the mechanisms through which circKMT2D and miR-210 could affect H₂O₂-treated MG63 cells. In addition, the effects of miR-210 on the expression of the autophagy-related proteins Beclin1 and p62 in H₂O₂-treated MG63 cells were detected by western blotting. An autophagy inhibitor was used to treat the MG63 cells, and whether miR-210 could affect the H₂O₂-treated MG63 cell phenotype through autophagy was investigated. The results demonstrated that H₂O₂ treatment promoted cell apoptosis and decreased cell viability, invasive ability and circKMT2D expression in MG63 and U2OS cells. Furthermore, circKMT2D knockdown decreased the cell viability and invasive ability and enhanced the apoptosis of H₂O₂-treated MG63 and U2OS cells. circKMT2D possessed binding sites for miR-210 and inhibited miR-210 expression. In H₂O₂-treated MG63 cells, miR-210 silencing partially reversed the circKMT2D knockdown-induced cell viability inhibition and apoptosis promotion. In addition, miR-210 elevated Beclin1 expression and decreased p62 expression in H₂O₂-treated MG63 cells. The use of the autophagy inhibitor partially reversed the miR-210 overexpression-induced promotion of apoptosis and inhibition of the viability and invasive ability of H₂O₂-treated MG63 cells. Taken together, these findings indicated that circKMT2D knockdown may contribute to the inhibition of H₂O₂-attenuated OS progression via miR-210/autophagy pathway.

Stannic Oxide Nanoparticle Regulates Proliferation, Invasion, Apoptosis, and Oxidative Stress of Oral Cancer Cells

Objective

To explore the effects of SnO₂ nanoparticles (NPs) on proliferation, invasion, apoptosis, and oxidative stress of oral cancer.

Methods

SnO₂ NPs were prepared and characterized. Oral cancer cell lines CAL-27 and SCC-9 were cultured in vitro. We detected the effects of various concentrations of SnO₂ NPs (0, 5, 25, 50, 100, 200 μg/mL) on the proliferation of oral cancer cells, and observed the morphological changes, and measured the cells ability of migration, invasion and apoptosis condition, and the levels of oxidative stress were measured by detecting malondialdehyde (MDA) and reactive oxygen species (ROS). Besides, we also measured the changes of mRNA and protein levels of factors related to cell proliferation, migration, invasion, apoptosis, and oxidative stress.

Results

SnO₂ NPs inhibited the proliferation of oral cancer cells in a concentration-dependent manner (all P < 0.05). And SnO₂ NPs treatment could reduce the migration and invasion ability of cells (all P < 0.05), induce apoptosis, and those effects were better when treated for 48 h than 24 h (all P < 0.05). And SnO₂ NPs could induce oxidative stress in cells (all P < 0.05). Besides, the concentrations of cyclin-D1, C-myc, matrix MMP-9, and MMP-2 in SnO₂ NPs treated group was decreased (all P < 0.05), and the expression levels of cleaved Caspase-3, cleaved Caspase-9, and Cytochrome C were increased (all P < 0.05).

Conclusion

In the present study, we found that SnO₂ NPs could play a cytotoxic role in oral cancer cells, and inhibit cell proliferation, migration, and invasion, and induce oxidative stress and apoptosis, which suggests that SnO₂ NPs may have the effects of anti-oral cancer. However, a more in-depth study is needed to determine its roles.

Rationally designed rapamycin-encapsulated ZIF-8 nanosystem for overcoming chemotherapy resistance

Zeolitic imidazolate framework-8 (ZIF-8) nanoparticles are widely reported as a pH-sensitive drug delivery carrier with high loading capacity for tumor therapy. However, the mechanism of intracellular corrosion of ZIF-8 and the corresponding biological effects especially for autophagy response have been rarely reported. Herein, the as-synthesized ZIF-8 was demonstrated to induce mTOR independent and pro-death autophagy. Interestingly, the autophagic process participated in the corrosion of ZIF-8. Subsequently, zinc ion release and the generation of reactive oxygen species due to its corrosion in the acidic compartments were directly responsible for tumor cell killing. In addition, ZIF-8 could sensitize tumor cells to chemotherapy by switching cytoprotective to death promoting autophagy induced by doxorubicin. The mTOR signaling pathway activation was demonstrated to restrict tumor chemotherapy efficiency. Hence, a combined platform rapamycin encapsulated zeolitic imidazolate frameworks (Rapa@ZIF-8) was constructed and demonstrated a more significant chemo-sensitized effect relative to ZIF-8 nanoparticles or rapamycin treatment alone. Lastly, the combined administration of Rapa@ZIF-8 and doxorubicin exhibited an outstanding synergistic antitumor effect without any obvious toxicity to the major organs of mice. Collectively, the optimized nanoplatform, Rapa@ZIF-8, provides a proof of concept for intentionally interfering mTOR pathway and utilizing the switch of survival-to death-promoting autophagy for adjunct chemotherapy.

Nanotechnology for angiogenesis: opportunities and challenges

Angiogenesis plays a critical role within the human body, from the early stages of life (i.e., embryonic development) to life-threatening diseases (e.g., cancer, heart attack, stroke, wound healing). Many pharmaceutical companies have expended huge efforts on both stimulation and inhibition of angiogenesis. During the last decade, the nanotechnology revolution has made a great impact in medicine, and regulatory approvals are starting to be achieved for nanomedicines to treat a wide range of diseases. Angiogenesis therapies involve the inhibition of angiogenesis in oncology and ophthalmology, and stimulation of angiogenesis in wound healing and tissue engineering. This review aims to summarize nanotechnology-based strategies that have been explored in the broad area of angiogenesis. Lipid-based, carbon-based and polymeric nanoparticles, and a wide range of inorganic and metallic nanoparticles are covered in detail. Theranostic and imaging approaches can be facilitated by nanoparticles. Many preparations have been reported to have a bimodal effect where they stimulate angiogenesis at low dose and inhibit it at higher doses.

Locally Controlled Release of Methotrexate and Alendronate by Thermo-Sensitive Hydrogels for Synergistic Inhibition of Osteosarcoma Progression

Osteosarcoma (OS) is a serious primary bone malignant tumor that can easily affect children and adolescents. Chemotherapy is one of the important and feasible clinical treatment strategies for the treatment of OS at present, which is severely limited due to insufficient retention time, poor penetration ability, and serious side effects of current anti-tumor drug preparations. In this work, a novel injectable thermo-sensitive hydrogel (mPEG₄₅-PLV₁₉) loaded with methotrexate and alendronate, and the sustained release at the tumor site synergistically inhibited the progression of OS. The mPEG₄₅-PLV₁₉ shows excellent physical and chemical properties. Compared with other treatment groups, the in vivo treatment of gel+ methotrexate + alendronate effectively inhibited the growth of tumor. More importantly, it significantly reduced bone destruction and lung metastasis caused by OS. Therefore, this injectable thermo-sensitive hydrogel drug delivery system has broad prospects for OS chemotherapy.

Targeted tumor therapy by autophagy of nanoparticles

Autophagy is an important biological mechanism that regulates the growth, death and energy metabolism of eukaryotic cells. It is also an active and evolutionarily conservative catabolic process to maintain homeostasis during cell stress response and cell survival. Autophagy maintains the body’s stability by degrading damaged proteins, organelles, cytoplasm and invasive microorganisms. Studies have found that autophagy also has a significant impact on the occurrence and development of tumors. Simultaneously, nanoparticles (NPs) can induce autophagy in cells, and the level of autophagy can be regulated by the synthesis design of NPs. Therefore, the study of the regulation of autophagy by NPs is of great significance for the treatment of cancer autocorrelation.

MicroRNA-744 promotes proliferation of osteosarcoma cells by targeting PTEN

MicroRNAs (miRNAs/miRs) are non-coding RNAs that regulate protein synthesis by targeting mRNAs for translational repression or degradation. Previous studies have reported that aberrant expression of miR‑744 may be involved in human osteosarcoma; however, the underlying mechanisms remain elusive. In the present study, the expression levels of miR‑744 and its downstream signals were determined by reverse transcription‑quantitative PCR and western blotting. Cell proliferation was assessed using the bromodeoxyuridine assay, and the target of miR‑744 was investigated using a dual‑luciferase activity assay. The present study identified a significant upregulation of miR‑744 in osteosarcoma tissues compared with adjacent non‑tumor tissues. Furthermore, it was demonstrated that ectopic overexpression of miR‑744 induced by a miR‑744 precursor significantly enhanced proliferation of the osteosarcoma cell line MG63, whereas opposite results were observed following suppression of miR‑744 with its inhibitor. Moreover, as a unique anti‑oncogene, PTEN was identified as a direct target of miR‑744. It was confirmed that miR‑744 downregulated PTEN expression in MG63 cells by targeting the PTEN 3'untranslated region, and that the downstream AKT signal was also regulated by miR‑744. Collectively, the present results suggested that miR‑744 promoted proliferation of human osteosarcoma cells by directly regulating the PTEN/AKT signaling pathway.

Inhibition of Autophagy via Lysosomal Impairment Enhances Cytotoxicity of Fullerenol under Starvation Condition

Autophagy is well-known as a common cellular response to nanomaterials. As one of the most comprehensively studied carbon-based nanomaterials, fullerene and its derivatives have been reported to bring about autophagic features in various cell lines, but little is known about the role of fullerenol (C₆₀(OH)₄₄) on the modulation of autophagy in human gastric tumor cell line SGC-7901. Fullerenol treatment led to the accumulation of autophagosomes, as evidenced by the increased fluorescent intensity of monodansylcadaverine (MDC) staining cells, an elevated level of LC3 protein, and the observation of auotphagosomes in cytoplasm. Subsequent results of the p62 level demonstrated that the accumulation of autophagosomes resulted from the blockade of autophagic flux rather than the activation of autophagy. Fullerenol disrupted autophagic flux by impairing lysosomal function, including lysosome membrane permeabilization (LMP), alkaline of lysosomes, and reduced activity of capthesin B. Interestingly, fullerenol treatment was noncytotoxic under a nutrient-rich condition. When serum was deprived, cytotoxicity occurred in a concentration- and time-dependent manner, along with massive vacuoles in cytoplasm, a large amount of ROS generation, and finally cell death, which can be ascribed to the disruption of essential autophagy in cells. Taken together, understanding this autophagy-lysosome pathway will shed light on the potential anticancer application of fullerenol.

Autophagy Modulated by Inorganic Nanomaterials

With the rapid development of nanotechnology, inorganic nanomaterials (NMs) have been widely applied in modern society. As human exposure to inorganic NMs is inevitable, comprehensive assessment of the safety of inorganic NMs is required. It is well known that autophagy plays dual roles in cell survival and cell death. Moreover, inorganic NMs have been proven to induce autophagy perturbation in cells. Therefore, an in-depth understanding of inorganic NMs-modulated autophagy is required for the safety assessment of inorganic NMs. This review presents an overview of a set of inorganic NMs, consisting of iron oxide NMs, silver NMs, gold NMs, carbon-based NMs, silica NMs, quantum dots, rare earth oxide NMs, zinc oxide NMs, alumina NMs, and titanium dioxide NMs, as well as how each modulates autophagy. This review emphasizes the potential mechanisms underlying NMs-induced autophagy perturbation, as well as the role of autophagy perturbation in cell fate determination. Furthermore, we also briefly review the potential roles of inorganic NMs-modulated autophagy in diagnosis and treatment of disease.

Recent Advances of Plasmonic Gold Nanoparticles in Optical Sensing and Therapy

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Gold nanoparticles with special surface plasmon resonance have been widely used in sensing and therapy because of their easy preparation, unique optical properties, excellent biocompatibility, etc. The applications of gold nanoparticles in chemo/biosensing, imaging, and therapy reported in 2016-2019, are summarized in this review. Regarding the gold nanoparticle-based sensing or imaging, sensing mechanisms and strategies are provided to illustrate the concepts for designing sensitive and selective detection platforms. Gold nanoparticlemediated therapy is introduced by surface plasmon resonance-based therapy and delivery-based therapy. Beyond the sole therapeutic system, platforms through synergistic therapy are also discussed. In the end, discussion of the challenges and future trends of gold nanoparticle-based sensing and therapy systems is described.

Pro-Death or Pro-Survival: Contrasting Paradigms on Nanomaterial-Induced Autophagy and Exploitations for Cancer Therapy

Autophagy is a critical lysosome-mediated cellular degradation process for the clearance of damaged organelles, obsolete proteins, and invading pathogens and plays important roles in the pathogenesis and treatment of human diseases including cancer. While not a cell death process per se, autophagy is nevertheless intimately linked to a cell's live/die decision. Basal autophagy, operating constitutively at low levels in essentially every mammalian cell, is vital for maintaining cellular homeostasis and promotes cell survival. On the other hand, elevated level of autophagy is frequently observed in cells responding to a physical, chemical, or biological stress. This "induced" autophagy, a hallmark under a variety of pathological and pathophysiological conditions, may be either pro-death or pro-survival, two contrasting paradigms for cell fate determination. Research in our laboratory and other groups around the world over the last 15 years has revealed nanomaterials as a unique class of autophagy inducers, with the capability of elevating the cellular autophagy to extremely high levels. In this Account we focus on the contrasting cell fate decision impacted by nanomaterial-induced autophagy. First, we give a brief introduction to nanomaterial-induced autophagy and summarize our current understanding on how it affects a cell's live/die decision. Autophagy induced by nanomaterials, in most cases, promotes cell death, but a significant number of nanomaterials are also able to elicit pro-survival autophagy. Although not a common feature, some nanomaterials may induce pro-death autophagy in one cell type while eliciting pro-survival autophagy in a different cell type. The ability to control the level of the induced autophagy, and furthermore its pro-death/pro-survival nature, is critically important for nanomedicine. Second, we discuss several possible mechanistic insights on the pro-death/pro-survival decision for nanomaterial-induced autophagy. "Disrupted" autophagic processes, with a "block" or perhaps "diversion" at the various stages, may be a characteristic hallmark for nanomaterial-induced autophagy, rendering it intrinsically pro-death in nature. On the other hand, autophagy-mediated upregulation and activation of pro-survival factors or signaling pathways, overriding the intrinsic pro-death nature, may be a common mechanism for nanomaterial-induced pro-survival autophagy. In addition, cargo degradation and reactive oxygen species may also play important roles in the pro-death/pro-survival decision impacted by nanomaterial-induced autophagy. Finally, we focus on the situation where nanomaterials induce autophagy in cancer cells and summarize the different strategies in exploiting the pro-death or pro-survival nature of nanomaterial-induced autophagy to enhance the various modalities of cancer therapy, including direct cancer cell killing, chemotherapy and radiotherapy, photothermal therapy, and integrated diagnosis and therapy. While the details vary, the basic principle is simple and straightforward. If the induced autophagy is pro-death, maximize it. Otherwise, inhibit it. Effective exploitation of nanomaterial-induced autophagy has the potential to become a new weapon in our ever-increasing arsenal to fight cancer, particularly difficult-to-treat and drug-resistant cancer.

Targeting autophagy is a promising therapeutic strategy to overcome chemoresistance and reduce metastasis in osteosarcoma

Osteosarcoma (OS) is the most common primary bone malignancy, mainly affecting children and adolescents. Currently, surgical resection combined with adjuvant chemotherapy has been standardized for OS treatment. Despite great advances in chemotherapy for OS, its clinical prognosis remains far from satisfactory; this is due to chemoresistance, which has become a major obstacle to improving OS treatment. Autophagy, a catabolic process through which cells eliminate and recycle their own damaged proteins and organelles to provide energy, can be activated by chemotherapeutic drugs. Accumulating evidence has indicated that autophagy plays the dual role in the regulation of OS chemoresistance by either promoting drug resistance or increasing drug sensitivity. The aim of the present review was to demonstrate thatautophagy has both a cytoprotective and an autophagic cell death function in OS chemoresistance. In addition, methods to detect autophagy, autophagy inducers and inhibitors, as well as autophagy‑mediated metastasis, immunotherapy and clinical prognosis are also discussed.