bims-istrec Biomed News
on Integrated stress response in cancer
Issue of 2022–04–10
thirteen papers selected by
the Vincenzo Ciminale lab, Istituto Oncologico Veneto
  1. An amino acid-defined diet impairs tumour growth in mice by promoting endoplasmic reticulum stress and mTOR inhibition.
  2. Endoplasmic Reticulum Stress of Oral Squamous Cell Carcinoma Induces Immunosuppression of Neutrophils.
  3. Pitavastatin Induces Cancer Cell Apoptosis by Blocking Autophagy Flux.
  4. Anti-Tumor and Anti-Invasive Effects of ONC201 on Ovarian Cancer Cells and a Transgenic Mouse Model of Serous Ovarian Cancer.
  5. MOXD1 knockdown suppresses the proliferation and tumor growth of glioblastoma cells via ER stress-inducing apoptosis.
  6. Evodiamine suppresses the progression of non-small cell lung carcinoma via endoplasmic reticulum stress-mediated apoptosis pathway in vivo and in vitro.
  7. 2-Deoxy-D-glucose increases the sensitivity of glioblastoma cells to BCNU through the regulation of glycolysis, ROS and ERS pathways: In vitro and in vivo validation.
  8. PDI inhibitor LTI6426 enhances panobinostat efficacy in preclinical models of multiple myeloma.
  9. Downregulation of Low-density lipoprotein receptor-related protein 1B (LRP1B) inhibits the progression of hepatocellular carcinoma cells by activating the endoplasmic reticulum stress signaling pathway.
  10. Spirocyclic dimer SpiD7 activates the unfolded protein response to selectively inhibit growth and induce apoptosis of cancer cells.
  11. Tetralol derivative NNC-55-0396 induces glioblastoma cell death by activating IRE1α, JNK1 and calcium signaling.
  12. Hsa_circ_0056686, derived from cancer-associated fibroblasts, promotes cell proliferation and suppresses apoptosis in uterine leiomyoma through inhibiting endoplasmic reticulum stress.
  13. Sevoflurane Induces Ferroptosis of Glioma Cells Through Activating the ATF4-CHAC1 Pathway.
  1. Mol Metab. 2022 Mar 30. pii: S2212-8778(22)00047-3. [Epub ahead of print] 101478
    An amino acid-defined diet impairs tumour growth in mice by promoting endoplasmic reticulum stress and mTOR inhibition.
    Maurizio Ragni, Chiara Ruocco, Laura Tedesco, Michele O Carruba, Alessandra Valerio, Enzo Nisoli.
       OBJECTIVE: Profound metabolic alterations characterize cancer development and, beyond glucose addiction, amino acid (AA) dependency is now recognized as a hallmark of tumour growth. Therefore, targeting the metabolic addiction of tumours by reprogramming their substrate utilization is an attractive therapeutic strategy. We hypothesized that a dietary approach targeted to stimulate oxidative metabolism could reverse the metabolic inflexibility of tumours and represent a proper adjuvant therapy.
    METHODS: We measured tumour development in xenografted mice fed with a designer, casein-deprived diet enriched in free essential amino acids (EAAs; SFA-EAA diet), or two control isocaloric, isolipidic, and isonitrogenous diets, identical to the SFA-EAA diet except for casein presence (SFA diet), or casein replacement by the free AA mixture designed on the AA profile of casein (SFA-CAA diet). Moreover, we investigated the metabolic, biochemical, and molecular effects of two mixtures that reproduce the AA composition of the SFA-EAA diet (i.e., EAAm) and SFA-CAA diet (i.e., CAAm) in diverse cancer and non-cancer cells.
    RESULTS: The SFA-EAA diet reduced tumour growth in vivo, promoted endoplasmic reticulum (ER) stress, and inhibited mechanistic/mammalian target of rapamycin (mTOR) activity in the tumours. Accordingly, in culture, the EAAm, but not the CAAm, activated apoptotic cell death in cancer cells without affecting the survival and proliferation of non-cancer cells. The EAAm increased branched-chain amino acid (BCAA) oxidation and decreased glycolysis, ATP levels, redox potential, and intracellular content of selective non-essential amino acids (NEAA) in cancer cells. The EAAm-induced NEAA starvation activated the GCN2-ATF4 stress pathway, leading to ER stress, mTOR inactivation, and apoptosis in cancer cells, unlike non-cancer cells.
    CONCLUSION: Together, these results confirm the efficacy of specific EAA mixtures in promoting cancer cells' death and suggest that manipulation of dietary EAA content and profile could be a valuable support to the standard chemotherapy for specific cancers.
    Keywords:  Branched-chain amino acids; Cancer metabolism; Essential amino acids; Glycolysis; Mechanistic/mammalian target of rapamycin; Mitochondria
    DOI:  https://doi.org/10.1016/j.molmet.2022.101478
  2. Front Oncol. 2022 ;12 818192
    Endoplasmic Reticulum Stress of Oral Squamous Cell Carcinoma Induces Immunosuppression of Neutrophils.
    Ching-Fang Wu, Tzu-Ting Hung, Yu-Chieh Su, Po-Jen Chen, Kuei-Hung Lai, Chih-Chun Wang.
      The endoplasmic reticulum (ER) stress of cancer cells not only determined cancer cell fate but also indirectly triggered proinflammatory or immunosuppressive responses of macrophages. In addition, ER stressed neutrophils were known to acquire immunosuppressive activity with surface expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). Since the importance of tumor ER stress and immunosuppressive neutrophils has been emphasized in head and neck cancers, we hypothesized that the ER stress of oral squamous cell carcinoma (OSCC) could transform neutrophils into LOX-1 expressing immunosuppressive phenotype. Two human OSCC cell lines, SCC25 and OML1, were treated with either vehicle or thapsigargin (THG), an ER stress inducer. These tumor conditioned media (TCM) were collected accordingly. Then human peripheral blood neutrophils from healthy donors were cultured in these TCM. The results showed that neutrophils cultured in THG-treated TCM had higher expression of LOX-1 compared with those cultured in vehicle-treated TCM. Moreover, by interleukin-2/anti-CD3/anti-CD28 activated autologous T cell proliferation assay, neutrophils conditioned by THG-treated TCM were shown to inhibit T cell proliferation more significantly than those conditioned by vehicle-treated TCM. These novel findings indicated that the ER stress of OSCC could be transmitted to neutrophils which in turn expressed LOX-1 and obtained immunosuppressive ability. Our findings further supported the existence of "transmissible" ER stress between tumor cells and neutrophils.
    Keywords:  endoplasmic reticulum stress; immunosuppression ; lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1); neutrophils; oral squamous cell carcinoma
    DOI:  https://doi.org/10.3389/fonc.2022.818192
  3. Front Pharmacol. 2022 ;13 854506
    Pitavastatin Induces Cancer Cell Apoptosis by Blocking Autophagy Flux.
    Nirmala Tilija Pun, Naeun Lee, Sang-Hoon Song, Chul-Ho Jeong.
      Statins, a class of lipid-lowering drugs, are used in drug repositioning for treatment of human cancer. However, the molecular mechanisms underlying statin-induced cancer cell death and autophagy are not clearly defined. In the present study, we showed that pitavastatin could increase apoptosis in a FOXO3a-dependent manner in the oral cancer cell line, SCC15, and the colon cancer cell line, SW480, along with the blockade of autophagy flux. The inhibition of autophagy by silencing the LC3B gene reduced apoptosis, while blockade of autophagy flux using its inhibitor, Bafilomycin A1, further induced apoptosis upon pitavastatin treatment, which suggested that autophagy flux blockage was the cause of apoptosis by pitavastatin. Further, the FOXO3a protein accumulated due to the blockade of autophagy flux which in turn was associated with the induction of ER stress by transcriptional upregulation of PERK-CHOP pathway, subsequently causing apoptosis due to pitavastatin treatment. Taken together, pitavastatin-mediated blockade of autophagy flux caused an accumulation of FOXO3a protein, thereby leading to the induction of PERK, ultimately causing CHOP-mediated apoptosis in cancer cells. Thus, the present study highlighted the additional molecular mechanism underlying the role of autophagy flux blockade in inducing ER stress, eventually leading to apoptosis by pitavastatin.
    Keywords:  ER stress; FOXO3a; apoptosis; autophagy flux blockade; pitavastatin
    DOI:  https://doi.org/10.3389/fphar.2022.854506
  4. Front Oncol. 2022 ;12 789450
    Anti-Tumor and Anti-Invasive Effects of ONC201 on Ovarian Cancer Cells and a Transgenic Mouse Model of Serous Ovarian Cancer.
    Yali Fan, Jiandong Wang, Ziwei Fang, Stuart R Pierce, Lindsay West, Allison Staley, Katherine Tucker, Yajie Yin, Wenchuan Sun, Weimin Kong, Varun Prabhu, Joshua E Allen, Chunxiao Zhou, Victoria L Bae-Jump.
      ONC201 is a promising first-in-class small molecule that has been reported to have anti-neoplastic activity in various types of cancer through activation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as well as activation of mitochondrial caseinolytic protease P (ClpP). The present study was to explore the anti-tumor potential effect of ONC201 in ovarian cancer cell lines and in a transgenic mouse model of high grade serous ovarian cancer under obese (high fat diet) and lean (low fat diet) conditions. ONC201 significantly suppressed cell proliferation, induced arrest in G1 phase, and increased cellular stress and apoptosis, accompanied by dual inhibition of the AKT/mTOR/S6 and MAPK pathways in OC cells. ONC201 also resulted in inhibition of adhesion and invasion via epithelial-mesenchymal transition and reduction of VEGF expression. Pre-treatment with the anti-oxidant, N-acetylcysteine (NAC), reversed the ONC201-induced oxidative stress response, and prevented ONC201-reduced VEGF and cell invasion by regulating epithelial-mesenchymal transition protein expression. Knockdown of ClpP in ovarian cancer cells reduced ONC201 mediated the anti-tumor activity and cellular stress. Diet-induced obesity accelerated ovarian tumor growth in the KpB mouse model. ONC201 significantly suppressed tumor growth, and decreased serum VEGF production in obese and lean mice, leading to a decrease in tumoral expression of Ki-67, VEGF and phosphorylation of p42/44 and S6 and an increase in ClpP and DRD5, as assessed by immunohistochemistry. These results suggest that ONC201 may be a promising therapeutic agent to be explored in future clinical trials in high-grade serous ovarian cancer.
    Keywords:  DRD2; ONC201; invasion; ovarian cancer; proliferation
    DOI:  https://doi.org/10.3389/fonc.2022.789450
  5. Cell Death Discov. 2022 Apr 07. 8(1): 174
    MOXD1 knockdown suppresses the proliferation and tumor growth of glioblastoma cells via ER stress-inducing apoptosis.
    Pengfei Shi, Jie Xu, Fanwei Xia, Yinggang Wang, Jie Ren, Ping Liang, Hongjuan Cui.
      Oxygenase-catalyzed reduction and activation of oxygen molecules and the incorporation of oxygen atoms into organic molecules are undoubtedly necessary in the process of tumor development, and it is also one of the research hotspots in recent years. MOXD1 belongs to the copper-dependent monooxygenase family. The expression of MOXD1 is one of the characteristics of early tumor development. However, it is not understandable that the biological function and molecular mechanism of MOXD1 in Glioblastoma (GBM). In this study, high MOXD1 expression is strongly associated with poor survival of the patient with GBM. Moreover. MOXD1 knockdown can inhibit cell viability, proliferation, migration, invasion, and tumorigenesis of GBM cells. This is also proven for the first time that MOXD1 can bind to β3GnT2 and affect the glycosylation modification of some proteins. In addition, knockdown of MOXD1 induces endoplasmic reticulum (ER) stress and triggers the ER-mitochondrial apoptosis pathway. Taken together, these results reveal that MOXD1 is involved in the occurrence and development of GBM, and also provide a new strategy for targeted therapy.
    DOI:  https://doi.org/10.1038/s41420-022-00976-9
  6. Int J Immunopathol Pharmacol. 2022 Jan-Dec;36:36 3946320221086079
    Evodiamine suppresses the progression of non-small cell lung carcinoma via endoplasmic reticulum stress-mediated apoptosis pathway in vivo and in vitro.
    Yuting Li, Yuming Wang, Xiaoqun Wang, Lulu Jin, Lu Yang, Jinli Zhu, Hongwu Wang, Fang Zheng, Huantian Cui, Xiaojiang Li, Yingjie Jia.
       BACKGROUND: Evodiamine (EVO) is one of the major components isolated from Evodia rutaecarpa (Juss.). Recent studies have shown that EVO has an anti-cancer effect. However, the pharmacological mechanism by which EVO impacts cancer is still poorly understood.
    OBJECTIVES: This study focused on asking the anti-cancer effect of EVO in human non-small cell lung carcinoma (NSCLC), and in particular to investigate whether EVO acts via modulating the endoplasmic reticulum stress (ERS)-mediated apoptosis pathway.
    MATERIALS AND METHODS: A Lewis lung carcinoma (LLC) tumor-bearing mouse model was treated with low-dose EVO (5 mg/kg) and high-dose EVO (10 mg/kg) intraperitoneally for 14 d. The effects of EVO on tumor growth, apoptosis, and ERS were assessed. In addition, NSCLC A549 and LLC cells were treated with EVO in vitro. The effects of EVO on cell proliferation, apoptosis, and ERS were investigated. Finally, 4-phenylbutyric acid (4-PBA), an ERS inhibitor, was used to validate whether EVO induced apoptosis of NSCLC cells by modulating ERS.
    RESULTS: EVO treatment significantly inhibited tumor growth in LLC tumor-bearing mice. H&E staining indicated that EVO treatment reduced the number of tumor cells and the nucleo-plasmic ratio. Immunostaining showed that EVO treatment significantly decreased the expression of Ki-67. TUNEL staining revealed that EVO induced apoptosis in the tumor. Likewise, EVO treatment up-regulated the expression of apoptosis-related genes and proteins and increased activation of the ERS pathway in the tumor. Additionally, EVO inhibited cell proliferation and increased cell apoptotic rates in A549 and LLC cells. EVO also increased the expression levels of genes and proteins associated with ERS-mediated apoptosis pathway in vitro. The effects of EVO on apoptosis were abolished by 4-PBA treatment.
    CONCLUSIONS: Our study demonstrated that EVO suppresses the progression of NSCLC by modulating the ERS-mediated apoptosis pathway.
    Keywords:  A549 cells; Evodiamine; apoptosis; endoplasmic reticulum stress; lewis lung carcinoma cells; non-small cell lung carcinoma
    DOI:  https://doi.org/10.1177/03946320221086079
  7. Biochem Pharmacol. 2022 Apr 04. pii: S0006-2952(22)00123-X. [Epub ahead of print]199 115029
    2-Deoxy-D-glucose increases the sensitivity of glioblastoma cells to BCNU through the regulation of glycolysis, ROS and ERS pathways: In vitro and in vivo validation.
    Xiaodong Sun, Tengjiao Fan, Guohui Sun, Yue Zhou, Yaxin Huang, Na Zhang, Lijiao Zhao, Rugang Zhong, Yongzhen Peng.
      Chloroethylnitrosoureas (CENUs) exert antitumor activity via producing dG-dC interstrand crosslinks (ICLs). However, tumor resistance make it necessary to find novel strategies to improve the therapeutic effect of CENUs. 2-Deoxy-D-glucose (2-DG) is a well-known glycolytic inhibitor, which can reprogram tumor energy metabolism closely related to tumor resistance. Here, we investigated the chemosensitization effect of 2-DG on l,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) against glioblastoma cells and the underlying mechanisms. We found that 2-DG significantly increased the inhibitory effects of BCNU on tumor cells compared with BCNU alone, while 2-DG showed no obvious enhancing effect on the BCNU-induced cytotoxicity for normal HaCaT and HA1800 cells. Proliferation, migration and invasion determinations presented the same trend as survival on tumor cells. 2-DG plus BCNU increased the energy deficiency through a more effective inhibition of glycolytic pathway. Notably, the combination of 2-DG and BCNU aggravated oxidative stress in glioblastoma cells, along with a significant decrease in glutathione (GSH) levels, and an increase in intracellular reactive oxygen species (ROS). Subsequently, we demonstrated that the combination treatment led to increased apoptosis via activating mitochondria and endoplasmic reticulum stress (ERS) related apoptosis pathways. Finally, we found that the dG-dC level was significantly increased after 2-DG pretreatment compared to BCNU alone by HPLC-ESI-MS/MS analysis. Finally, in vivo, 2-DG plus BCNU significantly suppressed tumor growth with lower side effects compared with BCNU alone in tumor-bearing mice. In summary, we proposed that 2-DG may have potential to increase the sensitivity of glioblastoma cells to BCNU by regulating glycolysis, ROS and ERS pathways in clinical setting.
    Keywords:  2-Deoxy-D-glucose; Antitumor mechanism; BCNU; Chemosensitization; Combination therapy; Glioblastoma cells
    DOI:  https://doi.org/10.1016/j.bcp.2022.115029
  8. Cancer Chemother Pharmacol. 2022 Apr 05.
    PDI inhibitor LTI6426 enhances panobinostat efficacy in preclinical models of multiple myeloma.
    Reeder M Robinson, Ashton P Basar, Leticia Reyes, Ravyn M Duncan, Hong Li, Nathan G Dolloff.
      The histone deacetylase inhibitor (HDACi), panobinostat (Pano), is approved by the United States Food and Drug Administration (FDA) and European Medicines Agency (EMA) for treatment of relapsed/refractory multiple myeloma (MM). Despite regulatory approvals, Pano is used on a limited basis in MM due largely to an unfavorable toxicity profile. The MM treatment landscape continues to evolve, and for Pano to maintain a place in that paradigm it will be necessary to identify treatment regimens that optimize its effectiveness, particularly those that permit dose reductions to eliminate unwanted toxicity. Here, we propose such a regimen by combining Pano with LTI6426, a first-in-class orally bioavailable protein disulfide isomerase (PDI) inhibitor. We show that LTI6426 dramatically enhances the anti-MM activity of Pano in vitro and in vivo using a proteasome inhibitor resistant mouse model of MM and a low dose of Pano that exhibited no signs of toxicity. We go on to characterize a transcriptional program that is induced by the LTI6426/Pano combination, demonstrating a convergence of the two drugs on endoplasmic reticulum (ER) stress pathway effectors ATF3 (Activating Transcription Factor 3), DDIT3/CHOP (DNA Damage Inducible Transcript 3, a.k.a. C/EBP Homologous Protein), and DNAJB1 (DnaJ homolog subfamily B member 1, a.k.a. HSP40). We conclude that LTI6426 may safely enhance low-dose Pano regimens and that ATF3, DDIT3/CHOP, and DNAJB1 are candidate pharmacodynamic biomarkers of response to this novel treatment regimen.
    Keywords:  Epigenetic therapy; Histone deacetylase; Multiple myeloma; Panobinostat; Protein disulfide isomerase
    DOI:  https://doi.org/10.1007/s00280-022-04425-3
  9. Bioengineered. 2022 Apr;13(4): 9467-9481
    Downregulation of Low-density lipoprotein receptor-related protein 1B (LRP1B) inhibits the progression of hepatocellular carcinoma cells by activating the endoplasmic reticulum stress signaling pathway.
    Zili Zhen, Zhemin Shen, Peilong Sun.
      Hepatocellular carcinoma (HCC) has a high recurrence rate and mortality rate even after surgery. Low-density lipoprotein receptor-related protein 1B (LRP1B) has proven to be involved in tumor development and progression of multiple malignancies. However, the function of LRP1B in HCC progression has not been fully elucidated. Thus, we conducted this study to explore the relationship between LRP1B and HCC. Bioinformatic analyses implied that LRP1B was highly expressed in HCC tissues. High LRP1B expression was shown to be related to poor outcomes and the determination of HCC patients' tumor stage. LRP1B deletion impeded the proliferation, migration, and invasion of HCC cells. Further investigation demonstrated that silencing LRP1B expression enhanced the sensitivity of HCC cells to doxorubicin. LRP1B deletion inhibited HCC progression by regulating the PERK-ATF4-CHOP signaling pathway. Additionally, we probed the genomic alterations of LRP1B in HCC and the impact on the prognosis of patients. Collectively, our results suggest that LRP1B plays an essential role in the promotion of HCC progression by regulating the PERK-ATF4-CHOP signaling pathway, which is a potential prognostic biomarker and a promising therapeutic target of HCC.
    Keywords:  LRP1B; PERK-ATF4-CHOP pathway; doxorubicin; hepatocellular carcinoma; prognosis; progression
    DOI:  https://doi.org/10.1080/21655979.2022.2060778
  10. J Biol Chem. 2022 Apr 01. pii: S0021-9258(22)00330-1. [Epub ahead of print] 101890
    Spirocyclic dimer SpiD7 activates the unfolded protein response to selectively inhibit growth and induce apoptosis of cancer cells.
    Smit Kour, Sandeep Rana, Sydney P Kubica, Smitha Kizhake, Mudassier Ahmad, Catalina Muñoz-Trujillo, David Klinkebiel, Sarbjit Singh, Jayapal Reddy Mallareddy, Surabhi Chandra, Nicholas T Woods, Adam R Karpf, Amarnath Natarajan.
      The unfolded protein response (UPR) is an adaptation mechanism activated to resolve transient accumulation of unfolded/misfolded proteins in the endoplasmic reticulum (ER). Failure to resolve the transient accumulation of such proteins results in UPR-mediated programmed cell death. Loss of tumor suppressor gene or oncogene addiction in cancer cells can result in sustained higher basal UPR levels; however, it is not clear if these higher basal UPR levels in cancer cells can be exploited as a therapeutic strategy. We hypothesized that covalent modification of surface-exposed cysteine (SEC) residues could simulate unfolded/misfolded proteins to activate the UPR, and that higher basal UPR levels in cancer cells would provide the necessary therapeutic window. To test this hypothesis, here we synthesized analogs that can covalently modify multiple SEC residues and evaluated them as UPR activators. We identified a spirocyclic dimer, SpiD7, and evaluated its effects on UPR activation signals, i.e., XBP1 splicing, phosphorylation of eIF2α, and a decrease in ATF6 levels, in normal and cancer cells, which were further confirmed by RNA-seq analyses. We found that SpiD7 selectively induced caspase-mediated apoptosis in cancer cells, while normal cells exhibited robust XBP1 splicing, indicating adaptation to ER stress. Furthermore, SpiD7 inhibited the growth of high-grade serous-carcinoma (HGSC) cell lines ∼3-15-fold more potently than immortalized fallopian tube epithelial (paired normal control) cells, and reduced clonogenic growth of HGSC cell lines. Our results suggest that induction of the UPR by covalent modification of SEC residues represents a cancer cell vulnerability and can be exploited to discover novel therapeutics.
    Keywords:  Small molecule; UPR; UPR activation; apoptosis; cancer cell vulnerability; isatin-derived spirocyclic dimer; protein misfolding
    DOI:  https://doi.org/10.1016/j.jbc.2022.101890
  11. Biomed Pharmacother. 2022 Mar 31. pii: S0753-3322(22)00270-0. [Epub ahead of print]149 112881
    Tetralol derivative NNC-55-0396 induces glioblastoma cell death by activating IRE1α, JNK1 and calcium signaling.
    Anna Visa, Lía Alza, Carles Cantí, Judit Herreros.
      Mibefradil and NNC-55-0396, tetralol derivatives with a proven -ability to block T-type calcium channels in excitable cells, reduce cancer cell viability in vitro, causing cell death. Furthermore, they reduce tumor growth in preclinical models of Glioblastoma multiforme (GBM), a brain tumor of poor prognosis. Here we found that GBM cells treated with cytotoxic concentrations of NNC-55-0396 paradoxically increased cytosolic calcium levels through the activation of inositol triphosphate receptors (IP3R) and ER stress. We used pharmacological inhibitors and gene silencing to dissect the cell death pathway stimulated by NNC-55-0396 in GBM cell lines and biopsy-derived cultures. Calcium chelation or IP3R inhibition prevented NNC-55-0396-mediated cytotoxicity, indicating that ER calcium efflux is the cause of cell death. Upstream of calcium mobilization, NNC-55-0396 activated the IRE1α arm of the Unfolded Protein Response (UPR) resulting in the nuclear translocation of pro-apoptotic CHOP. Consistent with these findings, silencing IRE1α or JNK1 rescued the cell death elicited by NNC-55-0396. Therefore, we demonstrate that activation of IRE1α and calcium signaling accounts for the cytotoxicity of NNC-55-0396 in GBM cells. The delineation of the signaling pathway that mediates the abrupt cell death triggered by this compound can help the development of new therapies for GBM.
    Keywords:  Calcium; Cell death; ER stress; Glioblastoma
    DOI:  https://doi.org/10.1016/j.biopha.2022.112881
  12. PLoS One. 2022 ;17(4): e0266374
    Hsa_circ_0056686, derived from cancer-associated fibroblasts, promotes cell proliferation and suppresses apoptosis in uterine leiomyoma through inhibiting endoplasmic reticulum stress.
    Meifang Suo, Zhichen Lin, Dongfang Guo, Airong Zhang.
      Abnormal expression of circular RNAs (circRNAs) in cancer-associated fibroblasts (CAFs) is involved in the tumor-promoting ability of CAFs. Hsa_ circ_ 0056686 has been reported to affect leiomyoma size. The purpose of this study is to investigate the regulatory role of hsa_circ_0056686 in CAFs on uterine leiomyoma (ULM). The primary CAFs and corresponding normal fibroblasts (NFs) were isolated from the tumor zones of ULM tissues and adjacent, respectively. Hsa_circ_0056686 level was higher in CAFs than NFs, and also higher in ULM tissues than in adjacent tissues. CAFs-CM significantly increased the proliferation and migration and inhibited apoptosis of ULM cells, as confirmed by CCK-8, transwell, and flow cytometry assays. Moreover, conditioned medium (CM) from CAFs transfected with hsa_circ_0056686 shRNA (CAFssh-circ_0056686-CM) abolished CAFs-mediated proliferation, migration and apoptosis of ULM cells. CAFs-CM suppressed the expression of endoplasmic reticulum stress (ERS) marker proteins and induced the expression of extracellular matrix (ECM) marker proteins, thus suppressing ERS and increasing ECM accumulation, which could be declined by CAFssh-circ_0056686-CM. Meanwhile, knockdown of hsa_circ_0056686 reversed the inhibitory effects of CAFs-CM on brefeldin A-induced cell apoptosis. Luciferase gene reporter and RNA pull-down assays indicated that miR-515-5p directly bound with hsa_circ_0056686. MiR-515-5p overexpression restored the hsa_circ_0056686-shRNA-mediated malignant biological behaviors of ULM cells. Hsa_circ_0056686 contributed to tumor-promoting effects of CAFs in ULM, manifested by promoting ULM cell proliferation and migration and reducing ERS-induced apoptosis through sponging miR-515-5p.
    DOI:  https://doi.org/10.1371/journal.pone.0266374
  13. Front Oncol. 2022 ;12 859621
    Sevoflurane Induces Ferroptosis of Glioma Cells Through Activating the ATF4-CHAC1 Pathway.
    Yingyi Xu, Na Zhang, Cheng Chen, Xinke Xu, Ailing Luo, Yaping Yan, Yanhua Lu, Jianhua Liu, Xinxu Ou, Yonghong Tan, Yufeng Liang, Lihe Chen, Xingrong Song, Xiaoping Liu.
       Objective: To clarify the function and mechanisms of sevoflurane (Sev) on ferroptosis in glioma cells.
    Methods: Different concentrations of Sev were used to treat glioma cells U87 and U251. Ferroptosis inducer Erastin was used to incubate glioma cells combined with Sev and ATF4 siRNA transfection treatment. CCK-8 assay and colorimetric assay were performed to analyze cell viability and Fe+ concentration, respectively. The releases of reactive oxygen species (ROS) were determined by flow cytometry analysis. Transcriptional sequencing was used to screen the differential genes affected by Sev in U251 cells. The mRNA and protein expression of ferroptosis-associated genes was detected by qRT-PCR and Western blotting.
    Results: Sev could suppress cell viability, increase ROS levels and Fe+ concentration, downregulate the protein expression levels of GPX4, and upregulate transferrin, ferritin, and Beclin-1 in a dose-dependent manner in U87 and U251 cells. The expression of ferroptosis and mitophagy-related gene activating transcription factor 4 (ATF4) was identified to be enhanced by Sev analyzed by transcriptional sequencing. ChaC glutathione-specific gamma-glutamylcyclotransferase 1 (CHAC1), which is involved in ferroptosis, is a downstream gene of ATF4. Inhibition of ATF4 could interrupt the expression of CHAC1 induced by Sev in U87 and U251 cells. Ferroptosis inducer Erastin treatment obviously inhibited the cell viability, elevated the Fe2+ concentration, and promoted ROS generation in U87 and U251 cells. The protein level of ATF4 and CHAC1 was increased in Erastin-treated U87 and U251 cells. Moreover, the interruption of Sev-induced ferroptosis and CHAC1 activating induced by ATF4 suppression could be reversed by Erastin.
    Conclusions: In summary, this study suggested that Sev exposure-induced ferroptosis by the ATF4-CHAC1 pathway in glioma cells.
    Keywords:  ATF4; CHAC1; ferroptosis; glioma; sevoflurane
    DOI:  https://doi.org/10.3389/fonc.2022.859621
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