β-Adrenergic signaling stimulates osteoclastogenesis via reactive oxygen species

2013 ◽  
Vol 304 (5) ◽  
pp. E507-E515 ◽  
Author(s):  
Hisataka Kondo ◽  
Shoko Takeuchi ◽  
Akifumi Togari
Keyword(s):  
Reactive Oxygen Species ◽  
Raw 264.7 Cells ◽  
Ros Generation ◽  
Raw 264.7 ◽  
Nuclear Factor ◽  
Oxygen Species ◽  
Adrenergic Signaling ◽  
Intracellular Ros

Sympathetic signaling regulates bone resorption through receptor activator of nuclear factor-κB ligand (RANKL) expression via the β-adrenergic receptor (β-AR) on osteoblasts. Reactive oxygen species (ROS) are known as one type of osteoclast regulatory molecule. Here we show that an antioxidant, α-lipoic acid (α-LA), treatment prevent the β-adrenergic signaling-induced bone loss by suppressing osteoclastogenesis, and sympathetic signaling directly regulates osteoclastogenesis through β2-AR expressed on osteoclasts via intracellular ROS generation. In an in vitro study, the β-AR agonist isoprenaline increased intracellular ROS generation in osteoclasts prepared from bone marrow macrophages (BBMs) and RAW 264.7 cells. Isoprenaline enhanced osteoclastogenesis through β2-AR expressed on BMMs and RAW 264.7 cells. The antioxidant α-LA inhibited isoprenaline-enhanced osteoclastogenesis. Isoprenaline increased the expression of osteoclast-related genes such as nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent 1, tartrate-resistant acid phosphatase, and cathepsin K on osteoclasts. α-LA also inhibited isoprenaline-induced increases of these gene expressions. These in vitro results led to the hypothesis that β-adrenergic signaling directly stimulates osteoclastogenesis via ROS generation. In an in vivo study, isoprenaline treatment alone caused oxidative damage in local bone and reduced bone mass because of an increase in bone resorption, and, in α-LA-treated mice, isoprenaline did not increase tibial osteoclast number even though the RANKL-to-osteoprotegerin ratio increased. These in vitro and in vivo results indicate that β-adrenergic signaling, at least in part, directly stimulates osteoclastogenesis through β2-AR on osteoclasts via ROS generation.

scholarly journals In vitro and in vivo anti-inflammatory activities of a sterol-enriched fraction from freshwater green alga, Spirogyra sp.

2020 ◽  
Vol 23 (1) ◽  
Author(s):  
Lei Wang ◽  
You-Jin Jeon ◽  
Jae-Il Kim
Keyword(s):  
Nitric Oxide ◽  
Green Alga ◽  
Raw 264.7 Cells ◽  
Ros Generation ◽  
Prostaglandin E ◽  
No Production ◽  
Raw 264.7 ◽  
Anti Inflammatory

Abstract Background Inflammation plays a crucial role in the pathogenesis of many diseases such as arthritis and atherosclerosis. In the present study, we evaluated anti-inflammatory activity of sterol-rich fraction prepared from Spirogyra sp., a freshwater green alga, in an effort to find bioactive extracts derived from natural sources. Methods The sterol content of ethanol extract of Spirogyra sp. (SPE) was enriched by fractionation with hexane (SPEH), resulting 6.7 times higher than SPE. Using this fraction, the in vitro and in vivo anti-inflammatory activities were evaluated in lipopolysaccharides (LPS)-stimulated RAW 264.7 cells and zebrafish. Results SPEH effectively and dose-dependently decreased the production of nitric oxide (NO) and prostaglandin E2 (PGE2). SPEH suppressed the production of pro-inflammatory cytokines including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and IL-1β through downregulating nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in LPS-stimulated RAW 264.7 cells without cytotoxicity. The in vivo test results indicated that SPEH significantly and dose-dependently reduced reactive oxygen species (ROS) generation, cell death, and NO production in LPS-stimulated zebrafish. Conclusions These results demonstrate that SPEH possesses strong in vitro and in vivo anti-inflammatory activities and has the potential to be used as healthcare or pharmaceutical material for the treatment of inflammatory diseases.

The histone Deacetylase Inhibitor Givinostat in Combination with Sorafenib Induces Reactive Oxygen Species (ROS) Generation and Exerts Potent Antitumor Effects in NOD/SCID Mice with Hodgkin Lymphoma Cell Line Xenografts

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3711-3711
Author(s):  
Silvia L Locatelli ◽  
Anna Guidetti ◽  
Loredana Cleris ◽  
Silvia Tartari ◽  
Alessandro M. Gianni ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Lines ◽  
Drug Combination ◽  
Fold Increase ◽  
Time Dependent ◽  
Ros Generation ◽  
Oxygen Species ◽  
Sorafenib Treatment

Abstract Abstract 3711 INTRODUCTION: Patients with refractory or relapsed classical Hodgkin Lymphoma (cHL) represent an unmet medical need and would benefit from the development of new therapies. Histone deacetylases (HDACs) and the RAF/MEK/ERK pathway are aberrantly controlled in cHL and influence a broad repertoire of tumor processes, suggesting a rationale for therapeutically targeting these pathways. We targeted these pathways using the HDAC inhibitor Givinostat (Italfarmaco S.p.A., Milan, Italy), and the RAF/MEK/ERK inhibitor Sorafenib (Nexavar, Bayer, Germany, EU) in order to investigate in vitro and in vivo the activity and mechanism(s) of action of this two-drug combination. METHODS: Three cHL cell lines, including HDLM-2, L-540 and HD-MyZ, were used to investigate the effects of Givinostat and Sorafenib, used alone or in combination, by means of in vitro assays evaluating cell growth and cell survival. Additionally, live cell imaging was used to asses the production of reactive oxygen species (ROS), and Western blotting (WB) to assess modulating effects of the two-drug combination on MAPK, PI3K/AKT, HDACs as well as the apoptotic pathways. The efficacy of Givinostat/Sorafenib combination was finally confirmed in NOD/SCID mice with cHL cell line xenografts. RESULTS: While Givinostat and Sorafenib as single agents exerted a limited activity against cHL cells, the combined Givinostat/Sorafenib treatment was associated with potent dephosphorylation of MAPK and PI3K/Akt pathways and significantly increased H3 and H4 acetylation due to a nearly complete inhibition of class I and II HDACs. Furthermore, these events were associated with a time-dependent synergistic cell growth inhibition (70% to 90%) in all Givinostat/Sorafenib-treated cHL cells. Upon Givinostat/Sorafenib exposure, HDLM-2 and L-540 cell lines showed significantly (P ≤.0001) increased levels of apoptosis (90 ± 2% and 96 ± 1%, respectively) and mitochondrial dysfunction (up to 70%, P≤.0001), as compared with single agents. Apoptosis induced by Givinostat/Sorafenib combination failed to induce processing of caspase-8, −9, −3, or cleavage of PARP, and was not reversed by the pan-caspase inhibitor Z-VADfmk, suggesting the occurrence of caspase-independent apoptosis. Besides downregulating the expression of the anti-apoptotic protein Mcl-1 and ERK1/2 phosphorylation, Givinostat/Sorafenib strongly increased expression of the BH-3 only protein Bim, compared to single treatments. These findings were dependent on a potent, early and time-dependent ROS generation (up to 60%, P≤.0001) that was synergistically induced by Givinostat/Sorafenib treatment. Additionally, pretreatment of cHL cells with the ROS inhibitor YCG063 prevented the generation of ROS as well as mitochondrial membrane depolarization along with cell death induced by the two-drug combination, suggesting that ROS generation is the triggering event in Givinostat/Sorafenib induced-cell death. In vivo Givinostat/Sorafenib treatment significantly reduced the growth of L-540 and HD-MyZ nodules, resulting in an average 35% to 65% tumor growth inhibition (P ≤.0001) compared to single treatments, in the absence of any toxicity. Interestingly, as compared to controls or treatment with single agents, the combined Givinostat/Sorafenib treatment significantly increased in vivo Bim expression (7- to 21-fold increase, P ≤.0001), resulting in a marked tumor necrosis (3- to 5-fold increase, P ≤.0001). CONCLUSIONS: The combined Givinostat/Sorafenib treatment demonstrates a potent preclinical in vitro and in vivo activity against cHL cell lines by targeting aberrant expression of HDACs and MAPK. Antitumor activity of this combination involves ROS generation and Bim upregulation and provides a rationale for clinical studies using this combination in refractory/relapsed cHL patients. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Ghrelin Ameliorates Diabetic Retinal Injury: Potential Therapeutic Avenues for Diabetic Retinopathy

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jie Bai ◽  
Fan Yang ◽  
Ruiqi Wang ◽  
Qinghui Yan
Keyword(s):  
Reactive Oxygen Species ◽  
Diabetic Retinopathy ◽  
Cell Damage ◽  
Reactive Oxygen ◽  
Diabetic Rats ◽  
Enzyme Linked Immunosorbent Assay ◽  
Ros Generation ◽  
Oxygen Species

Ghrelin has anti-inflammatory, antioxidant, and antiapoptotic effects, and it may be beneficial for the treatment of many ophthalmic diseases, such as cataract, uveitis, and glaucoma. Our previous work proved that ghrelin pretreatment reduced the apoptosis of lens epithelial cells induced by hydrogen peroxide, reduced the accumulation of reactive oxygen species (ROS), and effectively maintained the transparency of lens tissue. However, no study has yet investigated the effect of ghrelin on retina. In this study, we conducted in vitro and in vivo experiments to explore the effect of ghrelin on high-glucose- (HG-) induced ARPE-19 cell damage and diabetic retinopathy in streptozotocin-induced diabetic rats. ARPE-19 cells were incubated in a normal or an HG (30 mM glucose) medium with or without ghrelin. Cell viability was measured by 3-(4, 5-dimethylthiazol-3-yl)-2,5-diphenyl tetrazolium bromide assay, and apoptosis was detected by the Hoechst–PI staining assay. Intracellular reactive oxygen species (ROS) production levels within cells were measured using 2 ′ ,7 ′ -dichlorofluorescein diacetate staining, and the contents of superoxide dismutase and malondialdehyde were measured using relevant detection kits. The expression levels of IL-1β and IL-18 were measured using an enzyme-linked immunosorbent assay, and those of NLRP3, IL-1β, and IL-18 were measured using Western blotting. The rat diabetes models were induced using a single intraperitoneal injection of streptozotocin (80 mg/kg). The morphological and histopathological changes in the retinal tissues were examined. The results indicated that ghrelin reduced ROS generation, inhibited cell apoptosis and the activation of NLRP3 inflammasome, inhibited the apoptosis of retinal cells in diabetic rats, and protected the retina against HG-induced dysfunction. In conclusion, ghrelin may play a role in the treatment of ocular diseases involving diabetic retinopathy.

scholarly journals Azilsartan Suppresses Osteoclastogenesis and Ameliorates Ovariectomy-Induced Osteoporosis by Inhibiting Reactive Oxygen Species Production and Activating Nrf2 Signaling

2021 ◽  
Vol 12 ◽  
Author(s):  
Bin Pan ◽  
Lin Zheng ◽  
Jiawei Fang ◽  
Ye Lin ◽  
Hehuan Lai ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Signaling Pathways ◽  
Bone Microarchitecture ◽  
Reactive Oxygen ◽  
Related Factor ◽  
Nuclear Factor ◽  
Oxygen Species

Osteoporosis is characterized by a decrease in bone mass and destruction of the bone microarchitecture, and it commonly occurs in postmenopausal women and the elderly. Overactivation of osteoclasts caused by the inflammatory response or oxidative stress leads to osteoporosis. An increasing number of studies have suggested that intracellular reactive oxygen species (ROS) are strongly associated with osteoclastogenesis. As a novel angiotensin (Ang) II receptor blocker (ARB), azilsartan was reported to be associated with the inhibition of intracellular oxidative stress processes. However, the relationship between azilsartan and osteoclastogenesis is still unknown. In this study, we explored the effect of azilsartan on ovariectomy-induced osteoporosis in mice. Azilsartan significantly inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis and downregulated the expression of osteoclast-associated markers (Nfatc1, c-Fos, and Ctsk) in vitro. Furthermore, azilsartan reduced RANKL-induced ROS production by increasing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2). Mechanistically, azilsartan inhibited the activation of MAPK/NF-κB signaling pathways, while Nrf2 silencing reversed the inhibitory effect of azilsartan on MAPK/NF-κB signaling pathways. Consistent with the in vitro data, azilsartan administration ameliorated ovariectomy (OVX)-induced osteoporosis, and decreased ROS levels in vivo. In conclusion, azilsartan inhibited oxidative stress and may be a novel treatment strategy for osteoporosis caused by osteoclast overactivation.

scholarly journals 5-Hydroxymaltol Derived from Beetroot Juice through Lactobacillus Fermentation Suppresses Inflammatory Effect and Oxidant Stress via Regulating NF-kB, MAPKs Pathway and NRF2/HO-1 Expression

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1324
Author(s):  
Su-Lim Kim ◽  
Hack Sun Choi ◽  
Yu-Chan Ko ◽  
Bong-Sik Yun ◽  
Dong-Sun Lee
Keyword(s):  
Nitric Oxide ◽  
Reactive Oxygen Species ◽  
Mitogen Activated Protein Kinase ◽  
Raw 264.7 Cells ◽  
Heme Oxygenase 1 ◽  
Raw 264.7 ◽  
Related Factor ◽  
Nuclear Factor ◽  
Oxygen Species ◽  
Mitogen Activated Protein

Inflammation is the first response of the immune system against bacterial pathogens. This study isolated and examined an antioxidant derived from Lactobacillus fermentation products using cultured media with 1% beet powder. The antioxidant activity of the beet culture media was significantly high. Antioxidant activity-guided purification and repeated sample isolation yielded an isolated compound, which was identified as 5-hydoxymaltol using nuclear magnetic resonance spectrometry. We examined the mechanism of its protective effect on lipopolysaccharide (LPS)-induced inflammation of macrophages. 5-Hydroxymaltol suppressed nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells. It also suppressed tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and inducible nitric oxide synthase (iNOS) in the messenger RNA and protein levels in LPS-treated RAW 264.7 cells. Moreover, it suppressed LPS-induced nuclear translocation of NF-κB (p65) and mitogen-activated protein kinase activation. Furthermore, 5-hydroxymaltol reduced LPS-induced reactive oxygen species (ROS) production as well as increased nuclear factor erythroid 2–related factor 2 and heme oxygenase 1 expression. Overall, this study found that 5-hydroxymaltol has anti-inflammatory activities in LPS-stimulated RAW 264.7 macrophage cells based on its inhibition of pro-inflammatory cytokine production depending on the nuclear factor κB signaling pathway, inhibition of LPS-induced reactive oxygen species production, inhibition of LPS-induced mitogen-activated protein kinase induction, and induction of the nuclear factor erythroid 2–related factor 2/heme oxygenase 1 signaling pathway. Our data showed that 5-hydroxymaltol may be an effective compound for treating inflammation-mediated diseases.

270 MITOCHONDRIA AND REACTIVE OXYGEN SPECIES COLOCALIZATION IN IN VIVO AND IN VITRO MATURED OOCYTES FROM SUPEROVULATED ADULT EWES

2011 ◽  
Vol 23 (1) ◽  
pp. 233
Author(s):  
B. Ambruosi ◽  
N. A. Martino ◽  
M. Filioli Uranio ◽  
F. Silvestre ◽  
F. Binetti ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cumulus Cell ◽  
Reactive Oxygen ◽  
Oocyte Quality ◽  
Nuclear Chromatin ◽  
Oxygen Species ◽  
Fluorescent Intensity ◽  
Intracellular Ros

Analyses of energy and redox status parameters are emerging technologies to improve oocyte quality assessment. Mitochondria (mt) play a vital role in the oocyte to support maturation, fertilization, and pre-implantation development. They are the major source of reactive oxygen species (ROS) produced during oxidative phosphorylation, which are not only by-products of cell metabolism but also important molecules for regulation of intracellular cell signaling. The aim of the present study was to test for mt/ROS colocalization in oocytes recovered from superovulated adult ewes and examined after in vivo or in vitro maturation (IVM). Cumulus–oocyte complexes of 8 superovulated (fluorogestone acetate + D-cloprostenol for oestrus synchronization, pFSH/pLH and eCG for superovulation) adult (2 to 8 years of age) ewes were recovered (ovariohysterectomy by midventral laparotomy performed 54 h after vaginal sponge removal) either from flushing oviducts (oviducal oocytes) or from ovarian growing follicles (1–5 mm in diameter; follicular oocytes). Follicular oocytes were analysed after IVM (Ambruosi et al. 2009 Theriogenology 71, 1093–1104). After cumulus cell removal, all oocytes underwent nuclear chromatin, mt, and ROS evaluation. Hoechst 33258 and Mitotracker Orange CMTM Ros were used to label nuclear chromatin and mt (Ambruosi et al. 2009) and 2′,7′-dichloro-dihydro-fluorescein diacetate was used for ROS labelling (Hashimoto et al. 2000 Mol. Reprod. Dev. 57, 353–360). Oocytes at the metaphase II (MII) stage showing regular ooplasmic size (>130 μm in diameter) and morphology were selected for confocal analysis of mt/ROS fluorescence distribution, intensity, and colocalization. Forty oviducal MII oocytes recovered from 8 ewes were analysed. Thirty-two oocytes recovered from the ovaries of 4 ewes underwent IVM, and 23 out of 32 (72%) reached nuclear maturation and were analysed. The rate of oocytes showing perinuclear mt distribution pattern did not differ between oviducal and IVM oocytes (33%, 13/40 v. 43%, 10/23; not significant). In these oocytes, fluorescent intensity of mt labelling and intracellular ROS levels did not differ between oviducal and IVM ooocytes (996.27 ± 363.57 v. 798.13 ± 275.91; not significant; and 1808.11 ± 442.78 v. 1473.29 ± 662.49, for mt and ROS, respectively; not significant), whereas mt/ROS colocalization was significantly higher in ovulated oocytes than in IVM oocytes (Pearson coefficient 0.67 ± 0.11 v. 0.39 ± 0.19, respectively; P < 0.001). In conclusion, in oocytes of adult ewes, mt aggregation, apparent energy status, and intracellular ROS levels do not differ between ovulated and IVM oocytes, but mt/ROS colocalization differs between the 2 groups. As it was reported for other cell systems that such a difference can be indicative of healthy status of ovulated oocytes, we suggest that mt/ROS colocalization could be considered as a suitable marker of oocyte quality. Financial support was provided by Fondazione Cassa di Risparmio di Puglia 2008. Project: Salvaguardia di razze ovine autoctone pugliesi (R.U. DPA Resp. Sci. Prof. M. E. DellAquila).

scholarly journals Lycopus lucidus Turcz Inhibits the Osteoclastogenesis in RAW 264.7 Cells and Bone Loss in Ovariectomized Rat Model

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Da-Won Jeong ◽  
Eun-Young Kim ◽  
Jae-Hyun Kim ◽  
Bina Lee ◽  
SooYeon Hong ◽  
...  
Keyword(s):  
Bone Loss ◽  
Rat Model ◽  
Raw 264.7 Cells ◽  
Raw 264.7 ◽  
Nuclear Factor ◽  
Trap Activity ◽  
Gynecological Diseases ◽  
Lycopus Lucidus

Lycopus lucidus (LL) is a perennial herb that is traditionally used in Asia to treat edema, wound healing, and gynecological diseases such as irregular menstruation and menstrual pain. We hypothesized that LL would decrease the risk of developing osteoporosis, which is a condition related to gynecological diseases. In this study, we aimed to investigate the effect of a water extract of LL on osteoclastogenesis in vitro and osteoporosis in vivo. In vitro study, we used RAW 264.7 cells as osteoclast precursor cell. Osteoclast differentiation was induced by receptor activator nuclear factor-kappa B ligand (RANKL). We investigated the effect of LL on RANKL-induced osteoclastogenesis, tartrate-resistant acid phosphatase (TRAP) activity, and osteoclast-related genes. In vivo study, we used ovariectomized- (OVX-) induced osteoporosis rat model. OVX-induced Sprague-Dawley rats were randomly separated into sham, OVX, 17β-estradiol (100 μg/kg), wLL-L (15.2 mg/kg), and wLL-H (152 mg/kg) groups. Drugs were administered orally once daily for 9 weeks. wLL inhibited the formation of TRAP-positive osteoclasts; TRAP activity; pit formation; transcription factors (the nuclear factor of activated T-cell cytoplasmic 1 and c-fos); and osteoclast-related genes such as TRAP, carbonic anhydrase II, cathepsin K, osteoclast-associated receptor, and the d2 isoform of the vacuolar ATPase Vo domain. Also, wLL prevented loss of the trabecular area in the OVX femur without change of estrogen level. These results indicate that wLL is able to inhibit osteoclastogenesis and protect bone loss in the OVX-induced osteoporosis model without the influence of hormones like estrogen.

scholarly journals Modulation of reactive oxygen species by Rac1 or catalase prevents asbestos-induced pulmonary fibrosis

2009 ◽  
Vol 297 (5) ◽  
pp. L846-L855 ◽  
Author(s):  
Shubha Murthy ◽  
Andrea Adamcakova-Dodd ◽  
Sarah S. Perry ◽  
Linda A. Tephly ◽  
Richard M. Keller ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Pulmonary Fibrosis ◽  
Alveolar Macrophages ◽  
Reactive Oxygen ◽  
Ros Generation ◽  
Dependent Manner ◽  
Oxygen Species ◽  
Tnf Α

The release of reactive oxygen species (ROS) and cytokines by alveolar macrophages has been demonstrated in asbestos-induced pulmonary fibrosis, but the mechanism linking alveolar macrophages to the pathogenesis is not known. The GTPase Rac1 is a second messenger that plays an important role in host defense. In this study, we demonstrate that Rac1 null mice are protected from asbestos-induced pulmonary fibrosis, as determined by histological and biochemical analysis. We hypothesized that Rac1 induced pulmonary fibrosis via generation of ROS. Asbestos increased TNF-α and ROS in a Rac1-dependent manner. TNF-α was elevated only 1 day after exposure, whereas ROS generation progressively increased in bronchoalveolar lavage cells obtained from wild-type (WT) mice. To determine whether ROS generation contributed to pulmonary fibrosis, we overexpressed catalase in WT monocytes and observed a decrease in ROS generation in vitro . More importantly, administration of catalase to WT mice attenuated the development of fibrosis in vivo. For the first time, these results demonstrate that Rac1 plays a crucial role in asbestos-induced pulmonary fibrosis. Moreover, it suggests that a simple intervention may be useful to prevent progression of the disease.

scholarly journals Targeting autophagy enhances atezolizumab-induced mitochondria-related apoptosis in osteosarcoma

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Zhuochao Liu ◽  
Hongyi Wang ◽  
Chuanzhen Hu ◽  
Chuanlong Wu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Antitumor Immunity ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Specific Monoclonal Antibody ◽  
Osteosarcoma Cells ◽  
Jnk Pathway ◽  
In Vivo Experiments

AbstractIn this study, we identified the multifaceted effects of atezolizumab, a specific monoclonal antibody against PD-L1, in tumor suppression except for restoring antitumor immunity, and investigated the promising ways to improve its efficacy. Atezolizumab could inhibit the proliferation and induce immune-independent apoptosis of osteosarcoma cells. With further exploration, we found that atezolizumab could impair mitochondria of osteosarcoma cells, resulting in increased release of reactive oxygen species and cytochrome-c, eventually leading to mitochondrial-related apoptosis via activating JNK pathway. Nevertheless, the excessive release of reactive oxygen species also activated the protective autophagy of osteosarcoma cells. Therefore, when we combined atezolizumab with autophagy inhibitors, the cytotoxic effect of atezolizumab on osteosarcoma cells was significantly enhanced in vitro. Further in vivo experiments also confirmed that atezolizumab combined with chloroquine achieved the most significant antitumor effect. Taken together, our study indicates that atezolizumab can induce mitochondrial-related apoptosis and protective autophagy independently of the immune system, and targeting autophagy is a promising combinatorial approach to amplify its cytotoxicity.

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