bims-istrec Biomed News
on Integrated stress response in cancer
Issue of 2021‒10‒24
thirteen papers selected by
Vincenzo Ciminale’s Lab
Istituto Oncologico Veneto

  1. Cell Death Dis. 2021 Oct 18. 12(11): 960
      Aberrant activation of endoplasmic reticulum (ER) stress by extrinsic and intrinsic factors contributes to tumorigenesis and resistance to chemotherapies in various cancer types. Our previous studies have shown that the downregulation of PHLPP, a novel family of Ser/Thr protein phosphatases, promotes tumor initiation, and progression. Here we investigated the functional interaction between the ER stress and PHLPP expression in colon cancer. We found that induction of ER stress significantly decreased the expression of PHLPP proteins through a proteasome-dependent mechanism. Knockdown of PHLPP increased the phosphorylation of eIF2α as well as the expression of autophagy-associated genes downstream of the eIF2α/ATF4 signaling pathway. In addition, results from immunoprecipitation experiments showed that PHLPP interacted with eIF2α and this interaction was enhanced by ER stress. Functionally, knockdown of PHLPP improved cell survival under ER stress conditions, whereas overexpression of a degradation-resistant mutant PHLPP1 had the opposite effect. Taken together, our studies identified ER stress as a novel mechanism that triggers PHLPP downregulation; and PHLPP-loss promotes chemoresistance by upregulating the eIF2α/ATF4 signaling axis in colon cancer cells.
  2. Front Oncol. 2021 ;11 727583
      Endoplasmic reticulum (ER) stress is a cellular process in response to stress stimuli in protecting functional activities. However, sustained hyperactive ER stress influences tumor growth and development. Hepatocytes are enriched with ER and highly susceptible to ER perturbations and stress, which contribute to immunosuppression and the development of aggressive and drug-resistant hepatocellular carcinoma (HCC). ER stress-induced inflammation and tumor-derived chemokines influence the immune cell composition at the tumor site. Consequently, a decrease in the CCL23 chemokine in hepatic tumors is associated with poor survival of HCC patients and could be a mechanism hepatic tumor cells use to evade the immune system. This article describes the prospective role of CCL23 in alleviating ER stress and its impact on the HCC tumor microenvironment in promoting antitumor immunity. Moreover, approaches to reactivate CCL23 combined with immune checkpoint blockade or chemotherapy drugs may provide novel opportunities to target hepatocellular carcinoma.
    Keywords:  antitumor immunity; chemokine ligand CCL23; endoplasmic reticulum; hepatocellular carcinoma; tumor microenvironment
  3. Int J Mol Sci. 2021 Oct 17. pii: 11181. [Epub ahead of print]22(20):
      Aminosteroid derivative RM-581 was previously identified as an endoplasmic-reticulum (ER) stress inducer with potent in vitro and in vivo anticancer activities. We report its evaluation in androgen-independent prostate cancer (PC-3) cells. RM-581 efficiently blocks PC-3 cell proliferation with stronger activity than that of a selection of known antineoplastic agents. This later also showed a synergistic effect with docetaxel, able to block the proliferation of docetaxel-resistant PC-3 cells and, contrary to docetaxel, did not induce cell resistance. RM-581 induced an increase in the expression level of ER stress-related markers of apoptosis, potentially triggered by the presence of RM-581 in the ER of PC-3 cells. These in vitro results were then successfully translated in vivo in a PC-3 xenograft tumor model in nude mice, showing superior blockade than that of docetaxel. RM-581 was also able to stop the progression of PC-3 cells when they had become resistant to docetaxel treatment. Concomitantly, we observed a decrease in gene markers of mevalonate and fatty acid pathways, and intratumoral levels of cholesterol by 19% and fatty acids by 22%. Overall, this work demonstrates the potential of an ER stress inducer as an anticancer agent for the treatment of prostate cancers that are refractory to commonly used chemotherapy treatments.
    Keywords:  aminosteroid; cholesterol; endoplasmic reticulum stress; fatty acid; prostate cancer
  4. Antioxidants (Basel). 2021 Sep 28. pii: 1543. [Epub ahead of print]10(10):
      Ferroptosis is a type of programmed necrosis triggered by iron-dependent lipid peroxidation. We investigated the role of B-cell translocation gene 1 (BTG1) in cystine and methionine deficiency (CST/Met (-))-mediated cell death. CST/Met (-) depleted reduced and oxidized glutathione in hepatocyte-derived cells, increased prostaglandin-endoperoxide synthase 2 expression, and promoted reactive oxygen species accumulation and lipid peroxidation, as well as necrotic cell death. CST/Met (-)-mediated cell death and lipid peroxidation was specifically inhibited by pretreatment with ferroptosis inhibitors. In parallel with cell death, CST/Met (-) blocked global protein translation and increased the expression of genes associated with the integrated stress response. Moreover, CST/Met (-) significantly induced BTG1 expression. Using a BTG1 promoter-harboring reporter gene and siRNA, activating transcription factor 4 (ATF4) was identified as an essential transcription factor for CST/Met (-)-mediated BTG1 induction. Although knockout of BTG1 in human HAP1 cells did not affect the accumulation of reactive oxygen species induced by CST/Met (-), BTG1 knockout significantly decreased the induction of genes associated with the integrated stress response, and reduced lipid peroxidation and cell death in response to CST/Met (-). The results demonstrate that CST/Met (-) induces ferroptosis by activating ATF4-dependent BTG1 induction.
    Keywords:  B-cell translocation gene 1 (BTG1); activating transcription factor 4 (ATF4); cystine and methionine deficiency (CST/Met (−)); ferroptosis; hepatocyte-derived cells
  5. Acta Biochim Pol. 2021 Oct 20.
      The diarylheptanoid, 5-hydroxy-7-(4"-hydroxy-3"-metho-xyphenyl)-1-phenyl-3-heptanone (HPH), is isolated from rhizomes of Alpinia officinarum. There is no reported biological function for this compound other than the inhibition of pancreatic lipase. Cell viability, the expression of endoplasmic reticulum (ER) stress genes, the activation of ER stress sensors, and the induction of apoptosis and autophagy were confirmed following HPH treatment of PC12 cells. No cytotoxicity was observed when the cells were treated with 50 μg/ml HPH, but 40% cell death was observed using MTT assays with 100 μg/ml HPH. Although HPH did not change the expression of the ER chaperones PDI, binding BiP, and calnexin, it upregulated the expression of genes for the ER stress sensors ATF6, eIF2α, and PERK. HPH also induced apoptosis via the activation of ATF6 fragmentation, the phosphorylation of eIF2α, and XBP1 mRNA splicing. Eventually, the results of this study demonstrated that HPH induces apoptosis through upregulation of gene expression of ER stress sensors, which may provide a basis for the development of new drugs using HPH.
  6. Acta Biochim Biophys Sin (Shanghai). 2021 Oct 19. pii: gmab131. [Epub ahead of print]
      Cancer cells are often exposed to cell intrinsic stresses and environmental perturbations that may lead to accumulation of unfolded and/or misfolded proteins in the lumen of endoplasmic reticulum (ER), a cellular condition known as ER stress. In response to ER stress, the cells elicit an adaptive process called unfolded protein response (UPR) to cope with the stress, supporting cellular homeostasis and survival. The ER stress sensors inositol requiring protein 1α (IRE1α), eukaryotic translation initiation factor 2 alpha kinase 3 (EIF2AK3, also called PERK), and activating transcription factor 6 (ATF6) constitute the three branches of UPR to resolve ER stress. IRE1α, PERK, and ATF6 play an important role in tumor cell growth and survival. They are also involved in chemotherapy resistance of cancers. These have generated widespread interest in targeting these UPR branches for cancer treatment. In this review, we provide an overview of the role of IRE1α, PERK, and ATF6 in cancer progression and drug resistance and we summarize the research advances in targeting these UPR branches to enhance the efficacy of chemotherapy of cancers.
    Keywords:  ER stress; cancer; chemotherapy; drug resistance; unfolded protein response
  7. Toxins (Basel). 2021 Oct 14. pii: 727. [Epub ahead of print]13(10):
      Patulin, a mycotoxin, is known to have cytotoxic effects, but few studies have focused on the involvement of the endoplasmic reticulum (ER) stress response in patulin toxicity and the natural compounds that attenuate it in HepG2 cells. This study tested the ability of patulin to induce ER stress, and that of four thiols and three thioethers to attenuate patulin-induced ER stress in HepG2 cells. Patulin dose-dependently inhibited cell proliferation (IC50, 8.43 μM). Additionally, patulin was found to increase the expression levels of ER stress-related genes and/or protein markers, including BiP, CHOP, and spliced XBP1, in HepG2 cells compared to the vehicle control, indicating its potential in ER stress induction. Patulin-induced cytotoxicity in HepG2 cells was reduced by naturally occurring thiol compounds (glutathione, L-acetyl-L-cysteine, cysteine, and captopril), but not by thioether compounds (sulforaphane, sulforaphene, and S-allyl-L-cysteine). Patulin-thiol co-treatment decreased CHOP expression and BiP and CHOP levels in HepG2 cells but did not alter BiP expression. Spliced XBP1 expression was decreased by patulin-thiol co-treatment. Thus, patulin induced ER stress in HepG2 cells and thiols, but not in thioethers, attenuated patulin-induced ER stress.
    Keywords:  ER stress; HepG2 cells; mycotoxin; patulin; thiols
  8. RSC Med Chem. 2021 Sep 23. 12(9): 1604-1611
      The endoplasmic reticulum (ER) is one of the crucial sub-cellular organelles controlling myriads of functions including protein biosynthesis, folding, misfolding and unfolding. As a result, dysregulation of these pathways in the ER is implicated in cancer development and progression. Subsequently, targeting the ER in cancer cells emerged as an interesting unorthodox strategy in next-generation anticancer therapy. However, development of small molecules to selectively target the ER for cancer therapy remained elusive and unexplored. To address this, herein, we have developed a novel small molecule library of sulfonylhydrazide-hydrazones through a short and concise chemical synthetic strategy. We identified a fluorescent small molecule that localized into the endoplasmic reticulum (ER) of HeLa cells, induced ER stress followed by triggering autophagy which was subsequently inhibited by chloroquine (autophagy inhibitor) to initiate apoptosis. This small molecule showed remarkable cancer cell killing efficacy in different cancer cells as mono and combination therapy with chloroquine, thus opening a new direction to illuminate ER-biology towards the development of novel anticancer therapeutics.
  9. Int J Mol Sci. 2021 Oct 14. pii: 11073. [Epub ahead of print]22(20):
      Levels of O-GlcNAc transferase (OGT) and hyper-O-GlcNAcylation expression levels are associated with cancer pathogenesis. This study aimed to find conditions that maximize the therapeutic effect of cancer and minimize tissue damage by combining an OGT inhibitor (OSMI-1) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). We found that OSMI-1 treatment in HCT116 human colon cancer cells has a potent synergistic effect on TRAIL-induced apoptosis signaling. Interestingly, OSMI-1 significantly increased TRAIL-mediated apoptosis by increasing the expression of the cell surface receptor DR5. ROS-induced endoplasmic reticulum (ER) stress by OSMI-1 not only upregulated CHOP-DR5 signaling but also activated Jun-N-terminal kinase (JNK), resulting in a decrease in Bcl2 and the release of cytochrome c from mitochondria. TRAIL induced the activation of NF-κB and played a role in resistance as an antiapoptotic factor. During this process, O-GlcNAcylation of IκB kinase (IKK) and IκBα degradation occurred, followed by translocation of p65 into the nucleus. However, combination treatment with OSMI-1 counteracted the effect of TRAIL-mediated NF-κB signaling, resulting in a more synergistic effect on apoptosis. Therefore, the combined treatment of OSMI-1 and TRAIL synergistically increased TRAIL-induced apoptosis through caspase-8 activation. Conclusively, OSMI-1 potentially sensitizes TRAIL-induced cell death in HCT116 cells through the blockade of NF-κB signaling and activation of apoptosis through ER stress response.
    Keywords:  ER stress; NF-κB; O-GlcNAc transferase inhibitor; TRAIL; apoptosis
  10. Am J Cancer Res. 2021 ;11(9): 4607-4623
      The H3K27M oncohistone mutation, identified in approximately 80% of diffuse intrinsic pontine gliomas (DIPG), is a potential target for therapy. Imipridone ONC201/TIC10 (TRAIL-Inducing Compound #10) induces apoptosis of cancer cells, and has clinical efficacy against H3K27M-mutant DIPG. We demonstrate synergy between ONC201, ONC206 and ONC212, and targeted therapies with known preclinical activity against DIPG. We hypothesized that imipridone combinations with HDAC or proteasome inhibitors may be superior to single agent ONC201 treatment in H3K27M mutant DIPG. Six patient-derived DIPG cell lines (SU-DIPG-IV, SU-DIPG-13, SU-DIPG-25, SU-DIPG-27, SU-DIPG-29, SU-DIPG-36) were exposed to imipridones alone or combinations with histone de-acetylase inhibitors [HDACi], marizomib, etoposide, and temozolomide. Dose-dependent response to imipridones was observed in DIPG cells with half-maximal inhibitory concentration (IC50) of 1.46 µM, 0.11 µM, and 0.03 µM, for ONC201, ONC206, and ONC212, respectively. Upon treatment with the imipridones, DIPG cell lines engaged CLpP/CLPX, the integrated stress response with ATF4 activation, and TRAIL death receptor 5 (DR5) induction. Strong synergy was identified between ONC201 and HDACi panobinostat (combination index [CI] 0.01), romidepsin (CI 0.08) and proteasome inhibitor marizomib (CI 0.19). Synergy was demonstrated between ONC201 and etoposide (CI 0.54), although to a lesser degree than with panobinostat, romidepsin, and marizomib. ONC206 and ONC212 showed similar synergistic effects with panobinostat, romidepsin, and marizomib. Induction of apoptosis was demonstrated with imipridones and panobinostat or romidepsin combinations. Our results suggest increased sensitivity of H3K27M-mutant DIPG cell lines to second generation imipridone therapies, as compared to ONC201. Additionally, there is synergistic cell death with combination of imipridones and panobinostat, romidepsin, or marizomib, which may be further tested in vivo and in clinical trials.
    Keywords:  DIPG; Diffuse intrinsic pontine glioma; ONC201; ONC206; ONC212; imipridones; pediatric cancer
  11. Antioxidants (Basel). 2021 Sep 22. pii: 1503. [Epub ahead of print]10(10):
      Histone deacetylase inhibitors (HDACi) are emerging as anti-hepatocellular carcinoma (HCC) agents. However, the molecular mechanisms underlying HDACi-induced sensitization to oxidative stress and cell death of HCC remain elusive. We hypothesized that HDACi reduces the anti-oxidative stress capacity of HCC, rendering it more susceptible to oxidative stress and cell death. Change in the transcriptome of HCC was analyzed by RNA-seq and validated using real-time quantitative polymerase chain reaction (qPCR) and Western blot. Cell death of HCC was analyzed by fluorescence-activated cell sorting (FACS). Protein localization and binding on the target gene promoters were investigated by immunofluorescence (IF) and chromatin immunoprecipitation (ChIP), respectively. Glutathione peroxidase 8 (GPX8) was highly down-regulated in HCC upon oxidative stress and HDACi co-treatment. Oxidative stress and HDACi enhanced the expression and transcriptional activities of ER-stress-related genes. N-acetyl-cysteine (NAC) supplementation reversed the oxidative stress and HDACi-induced apoptosis in HCC. HDACi significantly enhanced the effect of ER stressors on HCC cell death. GPX8 overexpression reversed the activation of ER stress signaling and apoptosis induced by oxidative stress and HDACi. In conclusion, HDACi suppresses the expression of GPX8, which sensitizes HCC to ER stress and apoptosis by oxidative stress.
    Keywords:  ER stress; GPX8; HCC; HDACi; apoptosis; oxidative stress
  12. J Mol Biol. 2021 Oct 15. pii: S0022-2836(21)00531-3. [Epub ahead of print] 167294
      Activating mutations in the epidermal growth factor receptor (EGFR) are common driver mutations in non-small cell lung cancer (NSCLC). First, second and third generation EGFR tyrosine kinase inhibitors (TKIs) are effective at inhibiting mutant EGFR NSCLC, however, acquired resistance is a major issue, leading to disease relapse. Here, we characterize a small molecule, EMI66, an analog of a small molecule which we previously identified to inhibit mutant EGFR signalling via a novel mechanism of action. We show that EMI66 attenuates receptor tyrosine kinase (RTK) expression and signalling and alters the electrophoretic mobility of Coatomer Protein Complex Beta 2 (COPB2) protein in mutant EGFR NSCLC cells. Moreover, we demonstrate that EMI66 can alter the subcellular localization of EGFR and COPB2 within the early secretory pathway. Furthermore, we find that COPB2 knockdown reduces the growth of mutant EGFR lung cancer cells, alters the post-translational processing of RTKs, and alters the endoplasmic reticulum (ER) stress response pathway. Lastly, we show that EMI66 treatment also alters the ER stress response pathway and inhibits the growth of mutant EGFR lung cancer cells and organoids. Our results demonstrate that targeting of COPB2 with EMI66 presents a viable approach to attenuate mutant EGFR signalling and growth in NSCLC.
  13. J Cancer. 2021 ;12(22): 6787-6795
      Digestive cancer is one of the leading causes of cancer mortality in the world. Despite a number of studies being conducted, the exact mechanism for treating digestive cancer has not yet been fully understood. To survive, digestive cancer cells are subjected to various internal and external adverse factors, such as hypoxia, nutritional deficiencies or drug toxicity, resulting in accumulation of misfolded and unfolded protein in endoplasmic reticulum (ER) lumen further leading to ER stress and the unfolded protein response (UPR). During the last years, studies on the relationship between ER stress and microRNAs (miRNAs) has burst on the scene. miRNAs are non-coding RNAs with a length of 21~22nucleotides involved in post-transcriptional regulation of gene expression, which could be regarded as oncomiRs (tumor inducers) and tumor suppressors regulating cancer cell proliferation, invasion, and apoptosis by differently affecting the expression of genes related to cancer cell signaling. Therefore, investigating the interaction between ER stress and miRNAs is crucial for developing effective cancer treatment and prevention strategies. In this review, we mainly discuss miRNAs focusing on its regulation, role in ER stress induced apoptosis in Digestive cancer, expound the underlying mechanism, thus provides a theoretical foundation for finding new therapeutic targets of digestive cancer.
    Keywords:  ER stress; digestive cancers; miRNAs