bims-istrec Biomed News
on Integrated stress response in cancer
Issue of 2022‒02‒20
eleven papers selected by
Vincenzo Ciminale’s Lab
Istituto Oncologico Veneto

  1. Methods Mol Biol. 2022 ;2428 3-18
      Phosphorylation of the translation initiation factor eIF2α is an adaptive signaling event that is essential for cell and organismal survival from yeast to humans. It is central to the integrated stress response (ISR) that maintains cellular homeostasis in the face of threats ranging from viral infection, amino acid, oxygen, and heme deprivation to the accumulation of misfolded proteins in the endoplasmic reticulum. Phosphorylation of eIF2α has broad physiological, pathological, and therapeutic relevance. However, despite more than two decades of research and growing pharmacological interest, phosphorylation of eIF2α remains difficult to detect and quantify, because of its transient nature and because substoichiometric amounts of this modification are sufficient to profoundly reshape cellular physiology. This review aims to provide a roadmap for facilitating a robust evaluation of eIF2α phosphorylation and its downstream consequences in cells and organisms.
    Keywords:  ATF4; CHOP; Integrated stress response; PPP1R15A/GADD34; PPP1R15B/CReP; Signaling; Stress signaling; Translation; Unfolded protein response; eIF2α dephosphorylation; eIF2α phosphorylation
  2. Int J Mol Sci. 2022 Feb 04. pii: 1802. [Epub ahead of print]23(3):
      Derivatives of usnic acid (UA), a secondary metabolite from lichens, were synthesized to improve its anticancer activity and selectivity. Recently we reported the synthesis and activity of an UA isoxazole derivative, named 2b, against cancer cells of different origins. Herein, the molecular mechanisms underlying its activity and efficacy in vivo were tested. The viability of breast cancer or normal cells has been tested using an MTT assay. Cell and organelle morphology was analyzed using light, electron and fluorescence microscopy. Gene expression was evaluated by RNAseq and protein levels were evaluated by Western blotting. In vivo anticancer activity was evaluated in a mice xenograft model. We found that 2b induced massive vacuolization which originated from the endoplasmic reticulum (ER). ER stress markers were upregulated both at the mRNA and protein levels. ER stress was caused by the release of Ca2+ ions from the ER by IP3R channels which was mediated, at least partly, by phospholipase C (PLC)-synthetized 1,4,5-inositol triphosphate (IP3). ER stress led to cell death with features of apoptosis and paraptosis. When applied to nude mice with xenografted breast cancer cells, 2b stopped tumour growth. In mice treated with 2b, vacuolization was observed in tumour cells, but not in other organs. This study shows that the antiproliferative activity of 2b relates to the induction of ER stress in cancer, not in healthy, cells and it leads to breast cancer cell death in vitro and in vivo.
    Keywords:  ER stress; IP3R; anticancer activity; apoptosis; paraptosis; usnic acid
  3. J Cell Mol Med. 2022 Feb 14.
      The phytoalexin resveratrol exhibits anti-tumour activity in many types of cancer. In this study, we showed that resveratrol suppressed the survival of gastric tumour cells both in vivo and in vitro. Resveratrol promoted apoptosis, autophagy and endoplasmic reticulum (ER) stress in a dose-dependent manner. RNA-seq analysis showed that multiple cell death signalling pathways were activated after resveratrol treatment, while the use of ER stress activators (tunicamycin and thapsigargin) in combinatorial with resveratrol led to further inhibition of cancer cell survival. Results also showed that resveratrol altered the expression of several long non-coding RNAs (lncRNAs), including MEG3, PTTG3P, GAS5, BISPR, MALAT1 and H19. Knockdown of H19 in resveratrol-treated cells further enhanced the effects of resveratrol on apoptosis, ER stress and cell cycle S-phase arrest. Furthermore, the migratory ability of resveratrol-treated cells was dramatically decreased after H19 knockdown. In conclusion, resveratrol inhibited cancer cell survival, while knockdown of lncRNA H19 resulted in increased sensitivity to resveratrol therapy.
    Keywords:  ER stress; apoptosis; cancer; lncRNA; resveratrol
  4. Ann Clin Lab Sci. 2022 Jan;52(1): 40-47
      OBJECTIVE: Melatonin exhibits numerous anti-cancer activities in the treatment of human cancers. Nevertheless, the mechanisms of anti-gastric cancer effect of melatonin is still unclear. The aim of the study is to investigate the interaction between melatonin, endoplasmic reticulum (ER) stress, NF-κB signaling and HSF1 protein in gastric cancer cells.METHODS: In the current study, we used CCK-8, flow cytometry and Western blot to research anticancer mechanism of melatonin in AGS cells.
    RESULTS: The data demonstrated that melatonin could suppress cell proliferation and increase cell apoptosis. We explore that the ER stress and NF-kB signaling pathways play crucial roles in the cell apoptosis process. Of note, melatonin increased the expression of p-PERK and p-eIF2α, and decreased the expression of p-P65 and p-IκBα. A combination of melatonin and PERK inhibitor (GSK2606414) or NF-κB inhibitor (Bay11-7082) suppressed the activation PERK/eIF2α and NF-κB signaling pathway. Subsequently, the expression of HSF1 protein was upregulated by melatonin and kept its expression by Bay 11-7082.
    CONCLUSION: These results suggest that melatonin induces AGS cell apoptosis by up-regulating PERK/eIF2α and downregulating NF-κB signaling pathway.
    Keywords:  HSF1; NF-κB; PERK/eIF2α; apoptosis; gastric cancer; melatonin
  5. Anticancer Agents Med Chem. 2022 Feb 15.
      BACKGROUND: Tongue squamous cell carcinoma is a fatal disease characterized by high invasion and early metastasis. Dihydroartemisinin, an antimalarial drug with multiple biological activities, is reported to be a potential anti-cancer agent.OBJECTIVE: This study aimed to evaluate the antitumor effect of Dihydroartemisinin on tongue squamous cell carcinoma cells, and to identify the underlying mechanisms of Dihydroartemisinin-induced cell apoptosis.
    METHODS: Here, Cell Counting Kit 8 assay and colony formation assay were conducted to study cell proliferation. Annexin V-FITC/propidium iodide staining and western blot analysis were performed to analyze cell apoptosis. DCFH-DA probe was used to measure the generation of cellular reactive oxygen species. Endoplasmic reticulum stress activation was also determined via western blot analysis.
    RESULTS: The results showed that Dihydroartemisinin substantially inhibited cell proliferation and induced cell apoptosis in vivo. Moreover, reactive oxygen species production and endoplasmic reticulum stress activation were both observed after stimulation with Dihydroartemisinin. However, the reactive oxygen species inhibitor N-acetylcysteine significantly alleviated Dihydroartemisinin-induced endoplasmic reticulum stress and apoptosis.
    CONCLUSION: These results imply that Dihydroartemisinin induced cell apoptosis by triggering reactive oxygen species-mediated endoplasmic reticulum stress in CAL27 cells. In addition, Dihydroartemisinin might be an effective drug for tongue squamous cell carcinoma therapy.
    Keywords:  Dihydroartemisinin; anti-cancer; apoptosis; endoplasmic reticulum stress; reactive oxygen species; tongue squamous cell carcinoma
  6. Int J Mol Sci. 2022 Jan 25. pii: 1320. [Epub ahead of print]23(3):
      Interactions between the mitochondrial inner and outer membranes and between mitochondria and other organelles closely correlates with the sensitivity of ovarian cancer to cisplatin and other chemotherapeutic drugs. However, the underlying mechanism remains unclear. Recently, the mitochondrial protease OMA1, which regulates internal and external signals in mitochondria by cleaving mitochondrial proteins, was shown to be related to tumor progression. Therefore, we evaluated the effect of OMA1 on the response to chemotherapeutics in ovarian cancer cells and the mouse subcutaneous tumor model. We found that OMA1 activation increased ovarian cancer sensitivity to cisplatin in vivo and in vitro. Mechanistically, in ovarian cancer, OMA1 cleaved optic atrophy 1 (OPA1), leading to mitochondrial inner membrane cristae remodeling. Simultaneously, OMA1 induced DELE1 cleavage and its cytoplasmic interaction with EIF2AK1. We also demonstrated that EIF2AK1 cooperated with the ER stress sensor EIF2AK3 to amplify the EIF2S1/ATF4 signal, resulting in the rupture of the mitochondrial outer membrane. Knockdown of OMA1 attenuated these activities and reversed apoptosis. Additionally, we found that OMA1 protease activity was regulated by the prohibitin 2 (PHB2)/stomatin-like protein 2 (STOML2) complex. Collectively, OMA1 coordinates the mitochondrial inner and outer membranes to induce ovarian cancer cell death. Thus, activating OMA1 may be a novel treatment strategy for ovarian cancer.
    Keywords:  DELE1; OMA1; endoplasmic reticulum stress; mitochondrial membranes; ovarian cancer
  7. J Ethnopharmacol. 2022 Feb 10. pii: S0378-8741(22)00138-6. [Epub ahead of print] 115100
      ETHNOPHARMACOLOGICAL RELEVANCE: The natural extract glaucocalyxin A (GLA), purified from the aboveground sections of the Chinese traditional medicinal herb Rabdosia japonica (Burm. f.) Hara var. glaucocalyx (Maxim.) Hara, has various pharmacological benefits, such as anti-bacterial, anti-coagulative, anti-neoplastic, and anti-inflammatory activities. Although GLA has shown anti-tumor activity against various cancers, the therapeutic potential and biological mechanisms of GLA remain to be further explored in oral squamous cell carcinoma (OSCC).AIM OF THE STUDY: This study aimed to elucidate the therapeutic potential and regulatory mechanisms of GLA in OSCC.
    MATERIALS AND METHODS: The cell proliferation and apoptosis effects of GLA were analyzed by CCK-8, clone formation, Annexin V/PI staining, and apoptotic protein expression in vitro. An OSCC xenograft model was applied to confirm the anti-neoplastic effect in vivo. Furthermore, the changes of reactive oxygen species (ROS) were determined by DCFH-DA probe and GSH/GSSG assay, and inhibited by the pan-caspase inhibitor Z-VAD(OMe)-FMK and the ROS scavenger N-acetylcysteine (NAC). The modulation of GLA on mitochondria and ER-dependent apoptosis pathways was analyzed by JC-1 probe, quantitative real-time PCR, and Western blot. Finally, public databases, clinical samples, and transfection cells were analyzed to explore the importance of GLA's indirect targeting molecule CHAC1 in OSCC.
    RESULTS: GLA significantly inhibited cell proliferation and induced apoptosis in vitro and in vivo. GLA perturbed the redox homeostasis, and cell apoptosis was totally rescued by Z-VAD(OMe)-FMK and NAC. Furthermore, GLA activated the mitochondrial apoptosis pathway. Simultaneously, the overexpression and knockdown of CHAC1 dramatically affected GLA-mediated apoptosis. The endoplasmic reticulum stress-associated ATF4/CHOP signal was identified to participate in GLA-upregulated CHAC1 expression. Finally, we found that CHAC1 expression was lower in OSCC compared with normal tissues and positively correlated with 4-Hydroxynonenal (4-HNE) level. High CHAC1 expression also indicated better overall survival. Moreover, CHAC1 selectively regulated the viability of oral cancer cells.
    CONCLUSION: GLA is a promising therapeutic agent that activates the ROS-mediated ATF4/CHOP/CHAC1 axis in OSCC patients.
    Keywords:  Apoptosis; CHAC1; Endoplasmic reticulum stress; Glaucocalyxin A; Oral squamous cell carcinoma
  8. Int J Mol Sci. 2022 Jan 25. pii: 1345. [Epub ahead of print]23(3):
      A growing body of evidence indicates that dietary polyphenols show protective effects against various cancers. However, little is known yet about their activity in brain tumors. Here we investigated the interaction of dietary flavonoid quercetin (QCT) with the human glioblastoma A172 and LBC3 cell lines. We demonstrated that QCT evoked cytotoxic effect in both tested cell lines. Microscopic observations, Annexin V-FITC/PI staining, and elevated expression and activity of caspase 3/7 showed that QCT caused predominantly apoptotic death of A172 cells. Further analyses confirmed enhanced ROS generation, deregulated expression of SOD1 and SOD2, depletion of ATP levels, and an overexpression of CHOP, suggesting the activation of oxidative stress and ER stress upon QCT exposure. Finally, elevated expression and activity of caspase 9, indicative of a mitochondrial pathway of apoptosis, was detected. Conversely, in LBC3 cells the pro-apoptotic effect was observed only after 24 h incubation with QCT, and a shift towards necrotic cell death was observed after 48 h of treatment. Altogether, our data indicate that exposure to QCT evoked cell death via activation of intrinsic pathway of apoptosis in A172 cells. These findings suggest that QCT is worth further investigation as a potential pharmacological agent in therapy of brain tumors.
    Keywords:  ER stress; apoptosis; glioblastoma; necrosis; oxidative stress; quercetin
  9. Proc Natl Acad Sci U S A. 2022 Feb 22. pii: e2115624119. [Epub ahead of print]119(8):
      Cancer metabolism, including in mitochondria, is a disease hallmark and therapeutic target, but its regulation is poorly understood. Here, we show that many human tumors have heterogeneous and often reduced levels of Mic60, or Mitofilin, an essential scaffold of mitochondrial structure. Despite a catastrophic collapse of mitochondrial integrity, loss of bioenergetics, and oxidative damage, tumors with Mic60 depletion slow down cell proliferation, evade cell death, and activate a nuclear gene expression program of innate immunity and cytokine/chemokine signaling. In turn, this induces epithelial-mesenchymal transition (EMT), activates tumor cell movements through exaggerated mitochondrial dynamics, and promotes metastatic dissemination in vivo. In a small-molecule drug screen, compensatory activation of stress response (GCN2) and survival (Akt) signaling maintains the viability of Mic60-low tumors and provides a selective therapeutic vulnerability. These data demonstrate that acutely damaged, "ghost" mitochondria drive tumor progression and expose an actionable therapeutic target in metastasis-prone cancers.
    Keywords:  cell motility; metastasis; mitochondria
  10. Neuro Oncol. 2022 Feb 14. pii: noac041. [Epub ahead of print]
      BACKGROUND: Pediatric diffuse midline gliomas (DMGs) are incurable childhood cancers. The imipridone ONC201 has shown early clinical efficacy in a subset of DMGs. However, the anticancer mechanisms of ONC201 and its derivative ONC206 have not been fully described in DMGs.METHODS: DMG models including primary human in vitro (n=18), and in vivo (murine and zebrafish) models, and patient (n=20) frozen and FFPE specimens were used. Drug-target engagement was evaluated using in silico ChemPLP and in vitro thermal shift assay. Drug toxicity and neurotoxicity were assessed in zebrafish models. Seahorse XF Cell Mito Stress Test, MitoSOX and TMRM assays, and electron microscopy imaging were used to assess metabolic signatures. Cell lineage differentiation and drug-altered pathways were defined using bulk and single cell RNA-seq.
    RESULTS: ONC201 and ONC206 reduce viability of DMG cells in nM concentrations and extend survival of DMG PDX models (ONC201: 117 days, p=0.01; ONC206: 113 days, p=001). ONC206 is 10X more potent than ONC201 in vitro and combination treatment was the most efficacious at prolonging survival in vivo (125 days, p=0.02). Thermal shift assay confirmed that both drugs bind to ClpP, with ONC206 exhibiting a higher binding affinity as assessed by in silico ChemPLP. ClpP activation by both drugs results in impaired tumor cell metabolism, mitochondrial damage, ROS production, activation of integrative stress response and apoptosis in vitro and in vivo. Strikingly, imipridone treatment triggered a lineage shift from a proliferative, oligodendrocyte precursor-like state to a mature, astrocyte-like state.
    CONCLUSION: Targeting mitochondrial metabolism and ISR activation effectively impairs DMG tumorigenicity. These results supported initiation of a phase 1 pediatric clinical trial (PNOC023, NCT04732065).
    Keywords:  ClpP; ONC201; ONC206; diffuse midline glioma (DMG); integrated stress response (ISR)
  11. Cell Mol Life Sci. 2022 Feb 15. 79(2): 133
      BACKGROUND AND AIMS: Sec62 is a membrane protein of the endoplasmic reticulum that facilitates protein transport. Its role in cancer is increasingly recognised, but remains largely unknown. We investigated the functional role of Sec62 in gastric cancer (GC) and its underlying mechanism.METHODS: Bioinformatics, tissue microarray, immunohistochemistry (IHC), western blotting (WB), quantitative polymerase chain reaction (qPCR), and immunofluorescence were used to examine the expression of target genes. Transwell, scratch healing assays, and xenograft models were used to evaluate cell migration and invasion. Transmission electron microscopy and mRFP-GFP-LC3 double-labeled adenoviruses were used to monitor autophagy. Co-immunoprecipitation (CO-IP) was performed to evaluate the binding activity between the proteins.
    RESULTS: Sec62 expression was upregulated in GC, and Sec62 upregulation was an independent predictor of poor prognosis. Sec62 overexpression promoted GC cell migration and invasion both in vitro and in vivo. Sec62 promoted migration and invasion by affecting TIMP-1 and MMP2/9 balance. Moreover, Sec62 could activate autophagy by upregulating PERK/ATF4 expression and binding to LC3II with concomitant FIP200/Beclin-1/Atg5 activation. Furthermore, autophagy blockage impaired the promotive effects of Sec62 on GC cell migration and invasion, whereas autophagy activation rescued the inhibitory effect of Sec62 knockdown on GC metastasis. Notably, Sec62 inhibition combined with autophagy blockage exerted a synergetic anti-metastatic effect in vitro and in vivo.
    CONCLUSION: Sec62 promotes GC metastasis by activating autophagy and subsequently regulating TIMP-1 and MMP2/9 balance. The activation of autophagy by Sec62 may involve the unfolded protein response (UPR)-related PERK/ATF4 pathway and binding of LC3II during UPR recovery involving FIP200/Beclin-1/Atg5 upregulation. Specifically, the dual inhibition of Sec62 and autophagy may provide a promising therapeutic strategy for GC metastasis.
    Keywords:  EMT; ER stress; ER-phagy; Protein translocation machinery; Unfolded protein response (UPR)