Hsp70 inhibition induces myeloma cell death via the intracellular accumulation of immunoglobulin and the generation of proteotoxic stress.
Ontology highlight
ABSTRACT:
SUBMITTER: Zhang L
PROVIDER: S-EPMC3778988 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Proteostasis mechanisms, such as proteotoxic-stress response and autophagy, are increasingly recognized for their roles in influencing various cancer hallmarks such as tumorigenesis, drug resistance, and recurrence. However, the precise mechanisms underlying their coordination remain not fully elucidated. The aim of this study is to investigate the molecular interplay between Hsp70 and autophagy in lung adenocarcinoma cells and elucidate its impact on the outcomes of anticancer therapies in vitro. For this purpose, we utilized the human lung adenocarcinoma A549 cell line and genetically modified it by knockdown of Hsp70 or HSF1, and the H1299 cell line with knockdown or overexpression of Hsp70. In addition, several treatments were employed, including treatment with Hsp70 inhibitors (VER-155008 and JG-98), HSF1 activator ML-346, or autophagy modulators (SAR405 and Rapamycin). Using immunoblotting, we found that Hsp70 negatively regulates autophagy by directly influencing AMPK activation, uncovering a novel regulatory mechanism of autophagy by Hsp70. Genetic or chemical Hsp70 overexpression was associated with the suppression of AMPK and autophagy. Conversely, the inhibition of Hsp70, genetically or chemically, resulted in the upregulation of AMPK-mediated autophagy. We further investigated whether Hsp70 suppression-mediated autophagy exhibits pro-survival- or pro-death-inducing effects via MTT test, colony formation, CellTiter-Glo 3D-Spheroid viability assay, and Annexin/PI apoptosis assay. Our results show that combined inhibition of Hsp70 and autophagy, along with cisplatin treatment, synergistically reduces tumor cell metabolic activity, growth, and viability in 2D and 3D tumor cell models. These cytotoxic effects were exerted by substantially potentiating apoptosis, while activating autophagy via rapamycin slightly rescued tumor cells from apoptosis. Therefore, our findings demonstrate that the combined inhibition of Hsp70 and autophagy represents a novel and promising therapeutic approach that may disrupt the capacity of refractory tumor cells to withstand conventional therapies in NSCLC.
| S-EPMC11354248 | biostudies-literature
Project description:RNA-binding proteins (RBPs) are critical regulators of post-transcriptional gene expression, and aberrant RBP-RNA interactions can promote cancer progression. Here, we interrogate the function of RBPs in cancer using pooled CRISPR-Cas9 screening and identify 57 RBP candidates with distinct roles in supporting MYC-driven oncogenic pathways. We find that disrupting YTHDF2-dependent mRNA degradation triggers apoptosis in triple-negative breast cancer (TNBC) cells and tumors. eCLIP and m6A sequencing reveal that YTHDF2 interacts with mRNAs encoding proteins in the MAPK pathway that, when stabilized, induce epithelial-to-mesenchymal transition and increase global translation rates. scRibo-STAMP profiling of translating mRNAs reveals unique alterations in the translatome of single cells within YTHDF2-depleted solid tumors, which selectively contribute to endoplasmic reticulum stress-induced apoptosis in TNBC cells. Thus, our work highlights the therapeutic potential of RBPs by uncovering a critical role for YTHDF2 in counteracting the global increase of mRNA synthesis in MYC-driven breast cancers.
| S-EPMC8359670 | biostudies-literature
Project description:Exploiting protein homeostasis is a new therapeutic approach in cancer. Nelfinavir (NFV) is an HIV protease inhibitor that induces endoplasmic reticulum (ER) stress in cancer cells. Under conditions of ER stress, misfolded proteins are transported from the ER back to the cytosol for subsequent degradation by the ubiquitin-proteasome system. Bortezomib (BZ) is a proteasome inhibitor and interferes with degradation of misfolded proteins. Here, we show that NFV and BZ enhance proteotoxicity in non-small cell lung cancer (NSCLC) and multiple myeloma (MM) cells. The combination synergistically inhibited cell proliferation and induced cell death. Activating transcription factor (ATF)3 and CCAAT-enhancer binding protein homologous protein (CHOP), markers of ER stress, were rapidly increased, and their siRNA-mediated knockdown inhibited cell death. Knockdown of double-stranded RNA activated protein kinase-like ER kinase, a signal transducer in ER stress, significantly decreased apoptosis. Pretreatment with the protein synthesis inhibitor, cycloheximide, decreased levels of ubiquitinated proteins, ATF3, CHOP, and the overall total cell death, suggesting that inhibition of protein synthesis increases cell survival by relieving proteotoxic stress. The NFV/BZ combination inhibited the growth of NSCLC xenografts, which correlated with the induction of markers of ER stress and apoptosis. Collectively, these data show that NFV and BZ enhance proteotoxicity in NSCLC and MM cells, and suggest that this combination could tip the precarious balance of protein homeostasis in cancer cells for therapeutic gain.
| S-EPMC3406586 | biostudies-literature
Project description:Immunoglobulin M biosynthesis was studied with mouse plasma cell tumour MOPC 104E as a model system. Cell suspensions prepared from solid tumours were incubated in vitro with tritiated leucine; the radioactivity incorporated into intracellular and secreted proteins was analysed by polyacrylamide-gel electrophoresis, sucrose-density-gradient centrifugation and precipitation with rabbit antiserum specific for the macroglobulin. The tumour was found to secrete immunoglobulin M and light chains in a 1:2 weight ratio, with lag periods of 20-30min. Within the cells there was a 7s component precipitable with specific antiserum to the macroglobulin that was shown to consist of heavy and light chains. This 7s subunit of the macroglobulin appeared to accumulate in the intracellular environment, so that even after long periods of incubation (3hr.) no more than trace amounts of fully assembled 19s molecules could be detected in cell lysates. Polymerization of the subunits into the pentamer therefore appears to take place shortly before, or simultaneously with, secretion of the molecules.
| S-EPMC1185086 | biostudies-other
Project description:As a general rule, successful antineoplastic treatments induce an antitumor immune response, even if they were initially designed to target cancer cell-autonomous pathways. In this issue of Blood Cancer Discovery, Gulla and colleagues reveal that the proteasome inhibitor bortezomib induces immunogenic stress and death in multiple myeloma cells, thus explaining its therapeutic efficacy. See related article by Gulla et al., p. 468.
| S-EPMC8513917 | biostudies-literature
Project description:We found in this study through targeted CRISPR-Cas9 screening of RBPs that disrupting YTHDF2-dependent degradation of its target transcripts triggers apoptosis of MYC-dependent cancer cells and tumors. Enhanced CLIP (eCLIP), m6A-sequencing (m6A-seq) and YTHDF2 knockdown followed by RNA-seq analysis of YTHDF2-m6A-mRNA interactions revealed extensive associations with mRNAs encoding MAPK pathway genes that when stabilized, induce epithelial-to-mesenchymal transition and stress-induced apoptosis. scRibo-STAMP profiling of translating mRNAs revealed global alterations in the translatome of single cells in YTHDF2-depleted solid tumors. Thus, our work highlights the therapeutic relevance of RBPs by uncovering the critical role of YTHDF2 in counteracting the global increase of mRNA synthesis in MYC-driven cancers.
2021-07-02 | GSE137258 | GEO
Project description:Disruption of the Golgi apparatus can induce a distinct form of programmed cell death that has not been thoroughly characterized. We found that pharmacological application of Golgi stress leads to induction of death receptors (DRs) 4 and 5. DR4 appears to be primarily responsible for the initiation of cell death downstream of Golgi stress, whereas DR5 seems to be more important for cell death triggered by endoplasmic reticulum (ER) stress in specific cancer cell lines. DR induction downstream of either Golgi or ER stress mainly causes intracellular accumulation of DR4 presumably at the Golgi, rather than increased expression on the cell surface. Nevertheless, cells treated with secretory pathway stressors displayed an increased susceptibility to TRAIL (tumor necrosis factor related apoptosis inducing ligand), the endogenous ligand of DR4/5, probably due to intracellular sequestration of the caspase-8 regulator CFLAR (caspase-8 and FADD-like apoptosis regulator). These findings have implications for the treatment of cancer with DR agonists and our general understanding of DR signaling while highlighting the role of the Golgi apparatus as a cell death signaling platform.
| S-EPMC5680588 | biostudies-literature
Project description:Our objective was to determine whether lipocalin-2 (Lcn2) regulates cardiomyocyte apoptosis, the mechanisms involved, and the functional significance. Emerging evidence suggests that Lcn2 is a proinflammatory adipokine associated with insulin resistance and obesity-related complications, such as heart failure. Here, we used both primary neonatal rat cardiomyocytes and H9c2 cells and demonstrated for the first time that Lcn2 directly induced cardiomyocyte apoptosis, an important component of cardiac remodeling leading to heart failure. This was shown by detection of DNA fragmentation using TUNEL assay, phosphatidylserine exposure using flow cytometry to detect annexin V-positive cells, caspase-3 activity using enzymatic assay and immunofluorescence, and Western blotting for the detection of cleaved caspase-3. We also observed that Lcn2 caused translocation of the proapoptotic protein Bax to mitochondria and disruption of mitochondrial membrane potential. Using transient transfection of GFP-Bax, we confirmed that Lcn2 induced co-localization of Bax with MitoTracker® dye. Importantly, we used the fluorescent probe Phen Green SK to demonstrate an increase in intracellular iron in response to Lcn2, and depleting intracellular iron using an iron chelator prevented Lcn2-induced cardiomyocyte apoptosis. Administration of recombinant Lcn2 to mice for 14 days increased cardiomyocyte apoptosis as well as an acute inflammatory response with compensatory changes in cardiac functional parameters. In conclusion, Lcn2-induced cardiomyocyte apoptosis is of physiological significance and occurs via a mechanism involving elevated intracellular iron levels and Bax translocation.
| S-EPMC3281654 | biostudies-literature
Project description:Amyloid beta (Aβ) accumulates within neurons in the brains of early stage Alzheimer's disease (AD) patients. However, the mechanism underlying its toxicity remains unclear. Here, a triple omics approach was used to integrate transcriptomic, proteomic, and metabolomic data collected from a nerve cell model of the toxic intracellular aggregation of Aβ. It was found that intracellular Aβ induces profound changes in the omics landscape of nerve cells that are associated with a pro-inflammatory, metabolic reprogramming that predisposes cells to die via the oxytosis/ferroptosis regulated cell death pathway. Notably, the degenerative process included substantial alterations in glucose metabolism and mitochondrial bioenergetics. Our findings have implications for the understanding of the basic biology of proteotoxicity, aging, and AD as well as for the development of future therapeutic interventions designed to target the oxytosis/ferroptosis regulated cell death pathway in the AD brain.
| S-EPMC7538552 | biostudies-literature
Project description:The emergence of new drugs is a major feature of the treatment history of multiple myeloma (MM), which also reflects the current incurability of MM. As a unique member of cyclin dependent kinase (CDK) family, CDK5 participates in numerous tumorigenic or non‑tumorigenic processes. The aim of this study is to investigate the effects of CDK5 on the viability of MM cells and bortezomib resistance using western blotting, immunohistochemistry, transient transfection, MTT assays, cell cycle analysis, apoptosis assays and a myeloma xenograft mouse model. The present study found that MM patients with high CDK5 expression in the bone marrow do not respond well to bortezomib, have higher DS stage and worse prognosis. Genetic and pharmacological (dinaciclib) inhibition of CDK5 triggers MM cell viability inhibition. Dinaciclib induces G2/M arrest and apoptosis of MM cells. In vivo experiments with myeloma xenograft mice indicate that dinaciclib significantly reduces the volume of tumors with good tolerance. Dinaciclib combined with bortezomib exerts a synergistic anti‑myeloma activity accompanied by inhibiting the activation of the nuclear factor‑κB pathway. This study demonstrates the important role of CDK5 in the pathogenesis, viability, prognosis and resistance to bortezomib of MM, laying a solid theoretical foundation for further clinical use of CDK5 inhibitors.
| S-EPMC7169959 | biostudies-literature