bims-istrec Biomed News
on Integrated stress response in cancer
Issue of 2022‒04‒17
five papers selected by
Vincenzo Ciminale’s Lab
Istituto Oncologico Veneto

  1. Mol Carcinog. 2022 Apr 13.
      Molecularly targeted therapeutics have revolutionized the treatment of BRAFV600E -driven malignant melanoma, but the rapid development of resistance to BRAF kinase inhibitors (BRAFi) presents a significant obstacle. The use of clinical antimalarials for the investigational treatment of malignant melanoma has shown only moderate promise, attributed mostly to inhibition of lysosomal-autophagic adaptations of cancer cells, but identification of specific antimalarials displaying single-agent antimelanoma activity has remained elusive. Here, we have screened a focused library of clinically used artemisinin-combination therapeutic (ACT) antimalarials for the apoptotic elimination of cultured malignant melanoma cell lines, also examining feasibility of overcoming BRAFi-resistance comparing isogenic melanoma cells that differ only by NRAS mutational status (BRAFi-sensitive A375-BRAFV600E /NRASQ61 vs. BRAFi-resistant A375-BRAFV600E /NRASQ61K ). Among ACT antimalarials tested, mefloquine (MQ) was the only apoptogenic agent causing melanoma cell death at low micromolar concentrations. Comparative gene expression-array analysis (A375-BRAFV600E /NRASQ61 vs. A375-BRAFV600E /NRASQ61K ) revealed that MQ is a dual inducer of endoplasmic reticulum (ER) and redox stress responses that precede MQ-induced loss of viability. ER-trackerTM DPX fluorescence imaging and electron microscopy indicated ER swelling, accompanied by rapid induction of ER stress signaling (phospho-eIF2α, XBP-1s, ATF4). Fluo-4 AM-fluorescence indicated the occurrence of cytosolic calcium overload observable within seconds of MQ exposure. In a bioluminescent murine model employing intracranial injection of A375-Luc2 (BRAFV600E /NRASQ61K ) cells, an oral MQ regimen efficiently antagonized brain tumor growth. Taken together, these data suggest that the clinical antimalarial MQ may be a valid candidate for drug repurposing aiming at chemotherapeutic elimination of malignant melanoma cells, even if metastasized to the brain and BRAFi-resistant.
    Keywords:  ER stress; NRAS-driven BRAFi-resistance; antimalarial chemotherapeutics; brain metastases; gene expression array analysis; malignant melanoma; mefloquine
  2. Theranostics. 2022 ;12(6): 2987-3006
      Rationale: Multidrug resistance (MDR) and metastasis of breast cancer remain major hurdles in clinical anticancer therapy. The unsatisfactory outcome is largely due to insufficient cytotoxicity of chemotherapeutic agents and limited immunogenic cell death (ICD). On the other hand, efflux proteins, especially P-glycoprotein (P-gp), can recognize and promote the efflux of drugs from tumor cells. Methods: In this study, silver nanoparticles (Ag NPs) and peptide- functionalized doxorubicin (PDOX) were used to prepare a theranostic nanocomposite (Ag-TF@PDOX), which induced organelle-mediated immunochemotherapy and drug efflux protein inhibition in drug-resistant breast cancer cells (MCF-7/ADR) via a strategy based on endoplasmic reticulum (ER) stress and cell-nucleus penetration. Results: The silver nanoparticle-triggered persistent activation of ER stress synergizes with chemotherapy to enhance cytotoxicity and stimulate the ICD effect. It has the potential to enhance chemosensitivity by downregulating of P-gp expression due to the increased production of ATP-consuming chaperones. In addition, the novel peptide (CB5005), which not only penetrates the cell membrane but also has a nuclear localization sequence, is conjugated to DOX to improve both cellular internalization and intranuclear accumulation. Moreover, surface TA-Fe3+ engineering endows the nanocomposite with ATP-responsive disassembly and ATP depletion properties to improve biocompatibility and decrease ATP-dependent drug efflux. Ag-TF@PDOX has potential as a dual-mode (PAI/MRI) contrast-enhanced agent for realizing theranostic guidance. Conclusion: This theranostic nanocomposite greatly restricts the growth of drug-resistant breast tumors and activates a strong immune response as well, providing an opportunity for the development of therapeutics that reverse tumor MDR and metastasis at the subcellular level.
    Keywords:  ATP-responsive drug release; ER stress; cell-nucleus penetration; immunogenic cell death; multidrug resistance
  3. Int J Biol Sci. 2022 ;18(6): 2639-2651
      Due to increased drug and radiation tolerance, there is an urgent need to develop novel anticancer agents. In our previous study, we performed a series of structural modifications of ursolic acid (UA), a natural product of pentacyclic triterpenes, and found UA232, a derivative with stronger anti-tumor activity. In vitro experiments showed that UA232 inhibited proliferation, induced G0/G1 arrest, and promoted apoptosis in human breast cancer and cervical cancer cells. Mechanistic studies revealed that UA232 promoted apoptosis and induced protective autophagy via the protein kinase R-like endoplasmic reticulum kinase/activating transcription factor 4/C/EBP homologous protein-mediated endoplasmic reticulum stress. In addition, we also found that UA232 induced lysosomal biogenesis, increased lysosomal membrane permeability, promoted lysosomal protease release, and led to lysosome-dependent cell death. Furthermore, UA232 suppressed tumor growth in a mouse xenograft model. In conclusion, our study revealed that UA232 exerts multiple pharmacological effects against breast and cervical cancers by simultaneously triggering endoplasmic reticulum stress and lysosomal dysfunction. Thus, UA232 may be a promising drug candidate for cancer treatment.
    Keywords:  ER stress; apoptosis; autophagy; lysosomal membrane permeability
  4. Biomarkers. 2022 Apr 11. 1-34
      INTRODUCTION: Tumor cell apoptosis is a crucial indicator for judging the antiproliferative effects of anti-cancer drugs. The detection of optical and macromolecular biomarkers is the most common method for assessing the level of apoptosis. We aimed to explore the anti-tumor mechanisms of 6-methoxyflavone.MATERIAL AND METHODS: Three optical methods, including the percentage of apoptotic cells, cell morphology, and subcellular ultrastructure changes, were obtained using flow cytometry, inverted fluorescence microscopy, and transmission electron microscope imaging. The mRNA or protein expression of macromolecular biomarkers related to common apoptotic pathways was determined via polymerase chain reactions or western blot assays. The functional role of the core gene biomarker was investigated through overexpression, knockdown, and phosphorylation inhibitor (GSK2656157).
    RESULTS: Transcriptome sequencing and the optical biomarkers assays demonstrated that 6-methoxyflavone could induce apoptosis in HeLa cells. The expression of macromolecular biomarkers indicated that 6-methoxyflavone induced apoptosis through the PERK/EIF2α/ATF4/CHOP pathway. Phosphorylated PERK was identified as the core biomarker of this pathway. Both overexpression and GSK2656157 significantly altered the expression level of phosphorylated PERK in 6-methoxyflavone-treated HeLa cells.
    DISCUSSION AND CONCLUSION: Macromolecular biomarkers such as phosphorylated PERK and phosphorylated EIF2α are of great significance for assessing the therapeutic effects of 6-methoxyflavone.
    Keywords:  6-Methoxyflavone; EIF2α; PERK; apoptosis; biomarkers; cervical adenocarcinoma
  5. Cancer Res. 2022 Apr 11. pii: canres.3155.2021. [Epub ahead of print]
      Mitochondria and endoplasmic reticulum (ER) share structural and functional networks and activate well-orchestrated signaling processes to shape cells' fate and function. While persistent ER stress (ERS) response leads to mitochondrial collapse, moderate ERS promotes mitochondrial function. Strategies to boost anti-tumor T-cell function by targeting ER-mitochondria crosstalk have not yet been exploited. Here, we used carbon monoxide (CO), a short-lived gaseous molecule, to test if engaging moderate ERS conditions can improve mitochondrial and anti-tumor functions in T cells. In melanoma antigen-specific T cells, CO-induced transient activation of ERS sensor protein kinase R-like endoplasmic reticulum kinase (PERK) significantly increased anti-tumor T-cell function. Furthermore, CO-induced PERK activation temporarily halted protein translation and induced protective autophagy, including mitophagy. The use of LC3-GFP enabled differentiation between the cells that prepare themselves to undergo active autophagy (LC3-GFPpos) and those that fail to enter the process (LC3-GFPneg). LC3-GFPpos T cells showed strong anti-tumor potential, whereas LC3-GFPneg cells exhibited a T regulatory-like phenotype, harbored dysfunctional mitochondria, and accumulated abnormal metabolite content. These anomalous ratios of metabolites rendered the cells with a hypermethylated state and distinct epigenetic profile, limiting their anti-tumor activity. Overall, this study shows that ERS-activated autophagy pathways modify the mitochondrial function and epigenetically reprogram T cells towards a superior anti-tumor phenotype to achieve robust tumor control.