bims-istrec Biomed News
on Integrated stress response in cancer
Issue of 2022‒03‒20
ten papers selected by
Vincenzo Ciminale’s Lab
Istituto Oncologico Veneto

  1. Toxicol In Vitro. 2022 Mar 11. pii: S0887-2333(22)00043-1. [Epub ahead of print] 105346
      PURPOSE: Pendulone, an isoflavone compound, is known to act against human cancer cells. However, its role in human non-small cell lung cancer (NSCLC) and the exact molecular mechanisms of action have never been reported.METHODS: We investigated the effects of pendulone on cell proliferation and apoptosis in human NSCLC H1299 cells. Cell viability was examined using the methyl-thiazol-diphenyl-tetrazolium (MTT) assay. Flow cytometry was employed to evaluate apoptotic indices such as the cell cycle, mitochondrial membrane potential, cytochrome c release, caspase activity, and death receptor expression. The expression of proteins related to the cell cycle and apoptosis were analyzed by Western blot analysis.
    RESULTS: Pendulone significantly decreased H1299 cell viability by inducing endoplasmic reticulum (ER) stress through the accumulation of reactive oxygen species (ROS). Pendulone induced the expression of ER stress-associated proteins, such as ATF4 and CHOP, which promoted the expression of death receptors. Activation of caspase 8 induced extrinsic pathway apoptosis. Pendulone also caused the loss of mitochondrial membrane potential, inhibited the anti-apoptotic proteins BCL-2 and activated the pro-apoptotic protein BAX, which promoted the release of cytochrome c to activate caspase 9. Antioxidant N-acetylcysteine (NAC), with its ROS-suppressive property, reversed pendulone-induced ER stress and cell apoptosis.
    CONCLUSION: Our findings provide evidence that pendulone induces apoptosis by inducing ER stress through ROS accumulation and mitochondrial dysfunction in NSCLC cell lines.
    Keywords:  Apoptosis; Endoplasmic reticulum (ER); Non-small cell lung cancer (NSCLC); Pendulone; Reactive oxygen species (ROS)
  2. Bioengineered. 2022 Apr;13(4): 8076-8086
      Endoplasmic reticulum stress (ERS) is associated with breast cancer progression. However, the potential role of ribosomal protein L5 (RPL5) on ERS in breast cancer remains unclear. This study aimed to determine the role of RPL5/E2F transcription factor 1 (E2F1) in breast cancer. It was found that RPL5 was downregulated in breast cancer cells and tissues. Additionally, overexpression of RPL5 inhibited cell proliferation. Moreover, the levels of ERS and autophagy markers were estimated using western blotting. Overexpression of RPL5 induced ERS and suppressed autophagy. Additionally, RPL5 downregulated E2F1, which was overexpressed in breast cancer cells. However, E2F1 knockdown promoted the transcriptional activation of glucose regulated protein 78 (GRP78), suppressed ERS response, and promoted autophagy. Rescue assays indicated that the effects of RPL5 on ERS and autophagy were abolished by E2F1. Taken together, RPL5 inhibited the growth of breast cancer cells by modulating ERS and autophagy via the regulation of E2F1. These findings suggest that RPL5 has a tumor-suppressive effect in breast cancer.
    Keywords:  Breast cancer; E2F1; RPL5; autophagy; endoplasmic reticulum stress
  3. J Microbiol Biotechnol. 2022 Feb 23. 32(5): 1-8
      Gossypol, a natural phenolic aldehyde present in cotton plants, was originally used as a means of contraception, but is currently being studied for its anti-proliferative and anti-metastatic effects on various cancers. However, the intracellular mechanism of action regarding the effects of gossypol on pancreatic cancer cells remains unclear. Here, we investigated the anti-cancer effects of gossypol on human pancreatic cancer cells (BxPC-3 and MIA PaCa-2). Cell counting kit-8 assays, annexin V/propidium iodide staining assays, and transmission electron microscopy showed that gossypol induced apoptotic cell death and apoptotic body formation in both cell lines. RNA sequencing analysis also showed that gossypol increased the mRNA levels of CCAAT/enhancer-binding protein homologous protein (CHOP) and activating transcription factor 3 (ATF3) in pancreatic cancer cell lines. In addition, gossypol facilitated the cleavage of caspase-3 via protein kinase RNA-like ER kinase (PERK), CHOP, and Bax/Bcl-2 upregulation in both cells, whereas the upregulation of ATF was limited to BxPC-3 cells. Finally, a three-dimensional culture experiment confirmed the successful suppression of cancer cell spheroids via gossypol treatment. Taken together, our data suggest that gossypol may trigger apoptosis in pancreatic cancer cells via the PERK-CHOP signaling pathway. These findings propose a promising therapeutic approach to pancreatic cancer treatment using gossypol.
    Keywords:  CCAAT-enhancer-binding protein homologous protein; Gossypol; apoptosis; endoplasmic reticulum stress; pancreatic cancer
  4. Target Oncol. 2022 Mar 15.
      Estrogen receptor α (ERα) is a target for the treatment of ER-positive breast cancer patients. Paradoxically, it is also the initial site for estrogen (E2) to induce apoptosis in endocrine-resistant breast cancer. How ERα exhibits distinct functions, in different contexts, is the focus of numerous investigations. Compelling evidence demonstrated that unfolded protein response (UPR) is closely correlated with ER-positive breast cancer. Treatment with antiestrogens initially induces mild UPR through ERα with activation of three sensors of UPR-PRK-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α), and activating transcription factor 6 (ATF6)-in the endoplasmic reticulum. Subsequently, these sensors interact with stress-associated transcription factors such as c-MYC, nuclear factor-κB (NF-κB), and hypoxia-inducible factor 1α (HIF1α), leading to acquired endocrine resistance. Paradoxically, E2 further activates sustained secondary UPR via ERα to induce apoptosis in endocrine-resistant breast cancer. Specifically, PERK plays a key role in inducing apoptosis, whereas IRE1α and ATF6 are involved in endoplasmic reticulum stress-associated degradation after E2 treatment. Furthermore, persistent activation of PERK deteriorates stress responses in mitochondria and triggers of NF-κB/tumor necrosis factor α (TNFα) axis, ultimately determining cell fate to apoptosis. The discovery of E2-induced apoptosis has clinical relevance for treatment of endocrine-resistant breast cancer. All of these findings demonstrate that ERα and associated UPR are double-edged swords in therapy for ER-positive breast cancer, depending on the duration and intensity of UPR stress. Herein, we address the mechanistic progress on how UPR leads to endocrine resistance and commits E2 to inducing apoptosis in endocrine-resistant breast cancer.
  5. J Microbiol Biotechnol. 2022 Feb 16. 32(4): 1-11
      Forkhead transcription factor 3a (Foxo3a) is believed to be a tumor suppressor as its inactivation leads to cell transformation and tumor development. However, further investigation is required regarding the involvement of the activating transcription factor 3 (ATF3)-mediated Tat-interactive protein 60 (Tip60)/Foxo3a pathway in cancer cell apoptosis. This study demonstrated that Chelidonium majus upregulated the expression of ATF3 and Tip60 and promoted Foxo3a nuclear translocation, ultimately increasing the level of Bcl-2-associated X protein (Bax) protein. ATF3 overexpression stimulated Tip60 expression, while ATF3 inhibition by siRNA repressed Tip60 expression. Furthermore, siRNA-mediated Tip60 inhibition significantly promoted Foxo3a phosphorylation, leading to blockade of Foxo3a translocation into the nucleus. Thus, we were able to deduce that ATF3 mediates the regulation of Foxo3a by Tip60. Moreover, siRNA-mediated Foxo3a inhibition suppressed the expression of Bax and subsequent apoptosis. Taken together, our data demonstrate that Chelidonium majus induces SKOV-3 cell death by increasing ATF3 levels and its downstream proteins Tip60 and Foxo3a. This suggests a potential therapeutic role of Chelidonium majus against ovarian cancer.
    Keywords:  ATF3; Chelidonium majus; SKOV3; Tip60; apoptosis; ovarian cancer
  6. Cell Biol Int. 2022 Mar 16.
      Centrosome amplification (CA) refers to a numerical increase in centrosomes resulting in cells with more than two centrosomes. CA has been shown to initiate tumorigenesis and increase the invasive potential of cancer cells in genetically modified experimental models. Hexavalent chromium is a recognized carcinogen that causes CA and tumorigenesis as well as promotes cancer metastasis. Thus, CA appears to be a biological link between chromium and cancer. In the present study we investigated how chromium triggers CA. Our results showed that a sub-toxic concentration of chromium induced CA in HCT116 colon cancer cells, resulted in the production of reactive oxygen species (ROS), activated ATF6 without causing endoplasmic reticulum stress, and upregulated the protein level of PLK4. Inhibition of ROS production, ATF6 activation, or PLK4 upregulation attenuated CA. Inhibition of ROS using N-acetyl-L-cysteine (NAC) inhibited chromium-induced activation of ATF6 and upregulation of PLK4. ATF6-specific siRNA knocked down the protein level and activation of ATF6, and upregulated PLK4, with no effect on ROS production. Knockdown of PLK4 protein had no effect on chromium-induced ROS production or activation of ATF6. In conclusion, our results suggest that hexavalent chromium induces CA via the ROS-ATF6-PLK4 pathway and provides molecular targets for inhibiting chromium-mediated CA, which may be useful for the assessment of CA in chromium-promoted tumorigenesis and cancer cell metastasis. This article is protected by copyright. All rights reserved.
    Keywords:  ATF6; Centrosome amplification; Hexavalent chromium; PLK4; ROS; signaling pathway.
  7. Cell Signal. 2022 Mar 11. pii: S0898-6568(22)00068-7. [Epub ahead of print]93 110307
      Glutathione peroxidase 8 (GPx8) belongs to a family of enzymes that have a critical role in controlling levels of reactive oxygen species (ROS). GPX family members have been associated with several cancers. Here, we examined the role of GPx8 in esophageal squamous cell carcinoma (ESCC). Immunohistochemical staining and western blot analysis were used to study the clinical significance of GPx8 in ESCC tissue. GPx8 was further evaluated in cells by MTT assay and colony formation. RT-PCR, western blot, immunofluorescence staining, TUNEL assay, TEM, and flow cytometry were used to assess the molecular mechanism underlying endoplasmic reticulum (ER) stress associated with GPx8 in ESCC cells. Xenografted tumor growth was used to assess the in vivo role of GPx8. We found that GPx8 was overexpressed in both ESCC cell lines and tumor tissue. GPx8 knockdown significantly suppressed ESCC proliferation and induced autophagy and apoptosis in ESCC cell lines, whereas GPx8 overexpression led to increased proliferation and inhibition of apoptosis. GPx8-mediated inhibition of apoptosis was associated with the ER stress pathway through inositol-requiring enzyme 1 (IRE1) and Jun N-terminal kinase (JNK). Knockdown of GPx8 in xenograft models of ESCC resulted in a significant reduction in tumor weight and volume, which was further reduced with IRE1 or JNK inhibitors. Our study suggests that GPx8 regulates apoptosis and autophagy in ESCC through the IRE1/JNK pathway in response to ER stress. Targeting this pathway might be a potential therapeutic strategy for ESCC.
    Keywords:  Endoplasmic reticulum stress; Esophageal squamous cell carcinoma; Glutathione peroxidase 8; Inositol-requiring enzyme 1; Jun N-terminal kinase
  8. Cell Death Discov. 2022 Mar 14. 8(1): 114
      GSDMD is the key effector of pyroptosis, but its non-pyroptosis-related functions have seldom been reported. Here, we report that GSDMD is overexpressed in different types of tumours, including head and neck squamous-cell carcinoma, and it promotes the sensitivity of tumour cells to cisplatin. Unexpectedly, the enhanced cisplatin sensitivity is mediated by apoptosis but not pyroptosis, the well-known function of GSDMD. Furthermore, we found that GSDMD can activate the unfolded protein response by promoting the phosphorylation of eIF2α. Mechanistically, we demonstrated that GSDMD can directly bind to eIF2α and enhance the interaction between eIF2α and its upstream kinase PERK, leading to eIF2α phosphorylation. Consequently, the protein levels of ATF-4 were upregulated, downstream apoptosis-related proteins such as CHOP were activated, and apoptosis was induced. Remarkably, activation of endoplasmic-reticulum (ER) stress induced by GSDMD promotes cell apoptosis during cisplatin chemotherapy, thereby increasing the treatment sensitivity of tumours. Therefore, for the first time, our work reveals an unreported nonpyroptotic function of the classic pyroptosis protein GSDMD: it promotes cell apoptosis during cisplatin chemotherapy by inducing eIF2α phosphorylation and ER stress, which are related to the drug sensitivity of tumours. Our study also indicated that GSDMD might serve as a biomarker for cisplatin sensitivity.
  9. Adv Mater. 2022 Mar 15. e2201200
      Nanoparticles (NPs)-based cancer therapeutics is generally impeded by poor drug penetration into solid tumors due to their dense tumor extracellular matrix (ECM). Herein, we develop pH/redox-responsive dendritic polymer-based NPs to amplify the neighboring effect for improving drug penetration and driving cell apoptosis via combination therapy. Pyropheophorbide a (Ppa) is conjugated with PEGylated dendritic peptides via disulfide bonds and doxorubicin (DOX) encapsulated in the conjugate to construct dual-responsive NPs, PDPP@D. Delayed released DOX and Ppa from PDPP@D exert their combination therapeutic effect to induce cell apoptosis, and then they are liberated out of dying cells to amplify the neighboring effect, resulting in their diffusion through the dense ECM and penetration into solid tumors. Transcriptome studies reveal that PDPP@D leads to irreversible stress on the endoplasmic reticulum and inhibits cell protection through blocking the IRE1-dependent survival pathway and unleashing the DR5-mediated caspase activity to promote cell death. The strategy of amplifying the neighboring effect of NPs through combination therapy may offer great potential in enhancing drug penetration and eradicating solid tumors. This article is protected by copyright. All rights reserved.
    Keywords:  combination therapy; drug delivery; drug penetration; endoplasmic reticulum stresses; neighboring effect
  10. Cell Metab. 2022 Mar 08. pii: S1550-4131(22)00054-7. [Epub ahead of print]
      Immunotherapy has achieved limited success in patients with triple-negative breast cancer (TNBC), an aggressive disease with a poor prognosis. Commensal microbiota have been proven to colonize the mammary gland, but whether and how they modulate the tumor microenvironment remains elusive. We performed a multiomics analysis of a cohort of patients with TNBC (n = 360) and found genera under Clostridiales, and the related metabolite trimethylamine N-oxide (TMAO) was more abundant in tumors with an activated immune microenvironment. Patients with higher plasma TMAO achieved better responses to immunotherapy. Mechanistically, TMAO induced pyroptosis in tumor cells by activating the endoplasmic reticulum stress kinase PERK and thus enhanced CD8+ T cell-mediated antitumor immunity in TNBC in vivo. Collectively, our findings offer new insights into microbiota-metabolite-immune crosstalk and indicate that microbial metabolites, such as TMAO or its precursor choline, may represent a novel therapeutic strategy to promote the efficacy of immunotherapy in TNBC.
    Keywords:  antitumor immunity; commensal microbiota; immunotherapy; microbial metabolite; pyroptosis; trimethylamine N-oxide; triple-negative breast cancer