Glucose-regulated proteins in cancer: molecular mechanisms and therapeutic potential

GRP78 inhibitor YUM70 upregulates 4E-BP1 and suppresses c-MYC expression and viability of oncogenic c-MYC tumors

The 78-kDa glucose regulated protein (GRP78) commonly upregulated in a wide variety of tumors is an important prognostic marker and a promising target for suppressing tumorigenesis and treatment resistance. While GRP78 is well established as a major endoplasmic reticulum (ER) chaperone with anti-apoptotic properties and a master regulator of the unfolded protein response, its new role as a regulator of oncoprotein expression is just emerging. MYC is dysregulated in about 70 % of human cancers and is the most commonly activated oncoprotein. However, despite recent advances, therapeutic targeting of MYC remains challenging. Here we identify GRP78 as a new target for suppression of MYC expression. Using multiple MYC-dependent cancer models including head and neck squamous cell carcinoma and their cisplatin-resistant clones, breast and pancreatic adenocarcinoma, our studies revealed that GRP78 knockdown by siRNA or inhibition of its activity by small molecule inhibitors (YUM70 or HA15) reduced c-MYC expression, leading to onset of apoptosis and loss of cell viability. This was observed in 2D cell culture, 3D spheroid and in xenograft models. Mechanistically, we determined that the suppression of c-MYC is at the post-transcriptional level and that YUM70 and HA15 treatment potently upregulated the eukaryotic translation inhibitor 4E-BP1, which targets eIF4E critical for c-MYC translation initiation. Furthermore, knock-down of 4E-BP1 via siRNA rescued YUM70-mediated c-MYC suppression. As YUM70 is also capable of suppressing N-MYC expression, this study offers a new approach to suppress MYC protein expression through knockdown or inhibition of GRP78.

In Vivo Self-Sorting of Peptides via In Situ Assembly Evolution

Despite significant progress achieved in artificial self-sorting in solution, operating self-sorting in the body remains a considerable challenge. Here, we report an in vivo self-sorting peptide system via an in situ assembly evolution for combined cancer therapy. The peptide E3C16-SS-EIY consists of two disulfide-connected segments, E3C16SH and SHEIY, capable of independent assembly into twisted or flat nanoribbons. While E3C16-SS-EIY assembles into nanorods, exposure to glutathione (GSH) leads to the conversion of the peptide into E3C16SH and SHEIY, thus promoting in situ evolution from the nanorods into self-sorted nanoribbons. Furthermore, incorporation of two ligand moieties targeting antiapoptotic protein XIAP and organellar endoplasmic reticulum (ER) into the self-sorted nanoribbons allows for simultaneous inhibition of XIAP and accumulation surrounding ER. This leads to the cytotoxicity toward the cancer cells with elevated GSH levels, through activating caspase-dependent apoptosis and inducing ER dysfunction. In vivo self-sorting of E3C16-SS-EIY decorated with ligand moieties is thoroughly validated by tissue studies. Tumor-bearing mouse experiments confirm the therapeutic efficacy of the self-sorted assemblies for inhibiting tumor growth, with excellent biosafety. Our findings demonstrate an efficient approach to develop in vivo self-sorting systems and thereby facilitating in situ formulation of biomedical agents.

Programmable "triple attack" cancer therapy through in situ activation of disulfiram toxification combined with phototherapeutics

Effectively and completely eliminating residual tumor cells is the key to reducing the risk of tumor metastasis and recurrence. Designing an "ideal" nanoplatform for programmable cancer therapy has great prospects for completely eliminating residual tumor cells. Herein, an intelligent nanoplatform of disulfiram (DSF)-loaded CuS-tannic acid nanohexahedrons (denoted as "DSF-CuS@TA") with thermal- and pH-sensitive degradation, as well as near-infrared (NIR-II) phototherapeutics properties, was constructed. And then, it was employed for in situ DSF toxification activation programmable "triple attack" cancer therapy. After accumulating in the tumor, DSF-CuS@TA first releases the loaded Cu(DTC)2, and simultaneously degrades and releases Cu2+ and DSF under mildly acidic stimulation to trigger instant intratumoral Cu(DTC)2 chelation, thereby achieving the "first strike." Next, under irradiation by a NIR-II laser, light energy is converted into heat to generate NIR-II photothermal therapy, thereby achieving the second strike. Subsequently, under thermal stimulation, DSF-CuS@TA degrades further, triggering the chelation of Cu(DTC)2 for a second time to reach the third strike. As expected, in vitro and in vivo studies showed that the synergistic integration of DSF-based programmed chemotherapy and NIR-II phototherapeutics could achieve effective tumor removal. Therefore, we propose a novel type of programmed therapy against cancer by designing a nanoplatform via "nontoxicity-to-toxicity" chemical chelation transformation.

Intake of Special Amino Acids Mixture Leads to Blunted Murine Colon Cancer Growth In Vitro and In Vivo

Cancer cells require substantial amounts of energy and substrates for their metabolic hyperactivity, enabling the synthesis of new cells at the expense of healthy ones. Preliminary in vitro data suggest that a mix of free essential amino acids (EAA-mix) can promote cancer cell apoptosis by enhancing autophagy. This study aimed to confirm, both in vitro and in vivo, whether EAA intake could influence the development of colon cancer in mice. We investigated changes in cancer proliferation in CT26 cells treated with EAA-mix and in mice fed with EAA-rich modified diets (EAARD) as compared to those on a standard laboratory diet (StD). CT26 cells were injected subcutaneously (s.c.) or intraperitoneally (i.p.). After 21 days, tumors were removed and measured. In vitro data corroborated that EAA-mix impairs cancer growth by inducing apoptosis. In vivo data revealed that mice on StD developed significantly larger (s.c.) and more numerous (i.p.) cancers than those on EAARD. EAA administration appears to influence cancer cell survival with notable antiproliferative properties.

GRP75-dependent mitochondria-ER contacts ensure cell survival during early mouse thymocyte development

Mitochondria and endoplasmic reticulum contacts (MERCs) control multiple cellular processes, including cell survival and differentiation. Based on the observations that MERCs were specifically enriched in the CD4-CD8- double-negative (DN) stage, we studied their role in early mouse thymocyte development. We found that T cell-specific knockout of Hspa9, which encodes GRP75, a protein that mediates MERC formation by assembling the IP3R-GRP75-VDAC complex, impaired DN3 thymocyte viability and resulted in thymocyte developmental arrest at the DN3-DN4 transition. Mechanistically, GRP75 deficiency induced mitochondrial stress, releasing mitochondrial DNA (mtDNA) into the cytosol and triggering the type I interferon (IFN-I) response. The IFN-I pathway contributed to both the impairment of cell survival and DN3-DN4 transition blockage, while increased lipid peroxidation (LPO) played a major role downstream of IFN-I. Thus, our study identifies the essential role of GRP75-dependent MERCs in early thymocyte development and the governing facts of cell survival and differentiation in the DN stage.

AGR2: The Covert Driver and New Dawn of Hepatobiliary and Pancreatic Cancer Treatment

The anterior gradient protein 2 (AGR2) plays a crucial role in facilitating the formation of protein disulfide bonds within the endoplasmic reticulum (ER). Research suggests that AGR2 can function as an oncogene, with its heightened expression linked to the advancement of hepatobiliary and pancreatic cancers through invasion and metastasis. Notably, AGR2 not only serves as a pro-oncogenic agent but also as a downstream targeting protein, indirectly fostering cancer progression. This comprehensive review delves into the established functions and expression patterns of AGR2, emphasizing its pivotal role in cancer progression, particularly in hepatobiliary and pancreatic malignancies. Furthermore, AGR2 emerges as a potential cancer prognostic marker and a promising target for immunotherapy, offering novel avenues for the treatment of hepatobiliary and pancreatic cancers and enhancing patient outcomes.

CircRNA_0088196 Regulates Trophoblast Proliferation and Apoptosis in Preeclampsia Through the miR-379-5p/HSPA5 Axis

Existing research has confirmed the dysregulation of circular RNA (circRNA) in a wide variety of human diseases. Thus, in this study, we explored the potential mechanism of circRNA_0088196 in preeclampsia (PE). We performed quantitative real-time PCR to examine circRNA_0088196 expression and verified the function of circRNA_0088196 in vitro using CCK-8, TUNEL, flow cytometry, and Western blotting analyses. Additionally, we studied the mechanism using dual-luciferase reporter gene experiments. The results of our research revealed the up-regulation of circRNA_0088196 in PE patients' placentas and Heat Shock 70 kDa Protein 5 (HSPA5)-stimulated trophoblast (HTR-8/SVneo) cells. An investigation of the mechanism also showed that there was a binding between miR-379-5p and circRNA_0088196. Additionally, circRNA_0088196 inhibited HTR-8/SVneo cell proliferation and promoted cell apoptosis via the miR-337-3p/HSPA5 axis, thereby facilitating PE. In vivo experiments indicated that circRNA_0088196 regulated HTR-8/SVneo cell production through miR-379-5p. Overall, the findings of this study illustrate that circRNA_0088196 interference promotes cell apoptosis and inhibits HTR-8/SVneo proliferation via the miR-379-5p/HSPA5 axis, thereby accelerating the development of PE.

Enzyme-Empowered "Two Birds with One Stone" Strategy for Amplifying Tumor Apoptosis and Metabolic Clearance

Nanomedicine has reshaped the landscape of cancer treatment. However, its efficacy is still hampered by innate tumor defense systems that rely on adenosine triphosphate (ATP) for fuel, including damage repair, apoptosis resistance, and immune evasion. Inspired by the naturally enzymatic reaction of glucose oxidase (GOx) with glucose, here a novel "two birds with one stone" technique for amplifying enzyme-mediated tumor apoptosis and enzyme-promoted metabolic clearance is proposed and achieved using GOx-functionalized rhenium nanoclusters-doped polypyrrole (Re@ReP-G). Re@ReP-G reduces ATP production while increasing H2O2 concentrations in the tumor microenvironment through GOx-induced enzymatic oxidation, which in turn results in the downregulation of defense (HSP70 and HSP90) and anti-apoptotic Bcl-2 proteins, the upregulation of pro-apoptotic Bax, and the release of cytochrome c. These processes are further facilitated by laser-induced hyperthermia effect, ultimately leading to severe tumor apoptosis. As an enzymatic byproduct, H2O2 catalyzes the conversion of rhenium nanoclusters in Re@ReP-G nanostructures into rhenate from the outside in, which accelerates their metabolic clearance in vivo. This Re@ReP-G-based "two birds with one stone" therapeutic strategy provides an effective tool for amplifying tumor apoptosis and safe metabolic mechanisms.

How does the neuronal proteostasis network react to cellular cues?

Even though neurons are post-mitotic cells, they still engage in protein synthesis to uphold their cellular content balance, including for organelles, such as the endoplasmic reticulum or mitochondria. Additionally, they expend significant energy on tasks like neurotransmitter production and maintaining redox homeostasis. This cellular homeostasis is upheld through a delicate interplay between mRNA transcription-translation and protein degradative pathways, such as autophagy and proteasome degradation. When faced with cues such as nutrient stress, neurons must adapt by altering their proteome to survive. However, in many neurodegenerative disorders, such as Parkinson's disease, the pathway and processes for coping with cellular stress are impaired. This review explores neuronal proteome adaptation in response to cellular stress, such as nutrient stress, with a focus on proteins associated with autophagy, stress response pathways, and neurotransmitters.

A Universal and Programmable Platform based on Fluorescent Peptide-Conjugated Probes for Detection of Proteins in Organelles of Living Cells

Realizing protein analysis in organelles of living cells is of great significance for developing diagnostic and therapeutic methods of diseases. Fluorescent-labeled antibodies with well imaging performance and high affinity are classical biochemical tools for protein analysis, while due to the inability to effectively enter into cells, not to mention organelles and the uncontrollable reaction sites that might cause antibodies inactivation when chemically modification, they are hard to apply to living cells. Inspired by the structure of fluorescent-labeled antibodies, we designed as a universal detection platform that was based on the peptide-conjugated probes (PCPs) and consisted of three parts: a) a rotor type fluorescent molecular scaffold for conjugation and signal output; b) the cell penetration protein recognition unit; c) the subcellular organelle targeting unit. In living cells, PCPs could firstly localize at organelles and then proceed protein specific recognition, thus jointly leading to the restriction of twisted intramolecular charge transfer and activation of fluorescence signal. As a proof-of-concept, six different proteins in three typical intracellular organelles could be detected by our platform through simply replacing the recognition sequence of proteins and matching organelle targeting units. The position and intensity of fluorescence signals demonstrated specificity of PCPs and universality of the platform.

Discovery of the First-in-Class Inhibitors of Hypoxia Up-Regulated Protein 1 (HYOU1) Suppressing Pathogenic Fibroblast Activation

Fibroblasts are key regulators of inflammation, fibrosis, and cancer. Targeting their activation in these complex diseases has emerged as a novel strategy to restore tissue homeostasis. Here, we present a multidisciplinary lead discovery approach to identify and optimize small molecule inhibitors of pathogenic fibroblast activation. The study encompasses medicinal chemistry, molecular phenotyping assays, chemoproteomics, bulk RNA-sequencing analysis, target validation experiments, and chemical absorption, distribution, metabolism, excretion and toxicity (ADMET)/pharmacokinetic (PK)/in vivo evaluation. The parallel synthesis employed for the production of the new benzamide derivatives enabled us to a) pinpoint key structural elements of the scaffold that provide potent fibroblast-deactivating effects in cells, b) discriminate atoms or groups that favor or disfavor a desirable ADMET profile, and c) identify metabolic "hot spots". Furthermore, we report the discovery of the first-in-class inhibitor leads for hypoxia up-regulated protein 1 (HYOU1), a member of the heat shock protein 70 (HSP70) family often associated with cellular stress responses, particularly under hypoxic conditions. Targeting HYOU1 may therefore represent a potentially novel strategy to modulate fibroblast activation and treat chronic inflammatory and fibrotic disorders.

A novel mitochondria-related core gene signature to predict the prognosis and evaluate tumour microenvironment in CESC single-cell validation

Mitochondria and their related genes (MTRGs) are pivotal in the tumour microenvironment (TME) of cervical cancer, influencing prognosis and treatment response. This study developed a prognostic model using MTRGs to predict overall survival (OS) in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), aiming for personalized therapy. Analysing 14 MTRGs like ISCU and NDUFA11 through techniques such as univariate Cox regression, we found that a low mitochondrial (MT) score is associated with better survival, while a high MT score predicts poorer outcomes. The TME score, particularly influenced by CD8 T cells, also correlates with prognosis, with a high score indicating favourable outcomes. The interplay between MT and TME subtypes revealed that the best prognosis is seen in patients with a low MT and high TME score. Our findings highlight the role of MTRGs as potential biomarkers and therapeutic targets in cervical cancer, offering a novel approach to improving patient outcomes through a more nuanced understanding of mitochondrial function and immune interactions within the TME. This model presents a promising avenue for enhancing the precision of prognostic assessments in CESC.

Possible role of endoplasmic reticulum stress in the pathogenesis of chronic adenoiditis and adenoid hypertrophy: A prospective, parallel-group study

Background

Adenoid tissue is a first-line host defense secondary lymphoid organ, especially in childhood. The endoplasmic reticulum (ER) is required to maintain balanced cellular activity. With impaired ER functions, protein accumulation occurs, resulting in ER stress, which plays a role in the etiopathogenesis of many diseases.

Objective

We aimed to investigate the relationship between ER stress and adenoid tissue disorders, thereby elucidating the mechanisms of immunity-related diseases.

Methods

Fifty-four pediatric patients (>3 years old) who underwent adenoidectomy for chronic adenoiditis (CA) or adenoid hypertrophy (AH) were enrolled in this prospective, parallel-group clinical study. Adenoids were divided into two groups (CA or AH) based on their size and evaluated for ER stress pathway and apoptosis pathway markers by Real-time PCR and Western blot analysis.

Results

ER stress pathway markers significantly differed between the CA and AH groups. Children with CA had higher ER stress marker levels than the AH group (p < .001 for ATF-4, ATF-6, and GRP78, and p < .05 for EDEM1, CHOP, EIF2AK3, ERNI, and GRP94). Apoptosis pathway marker levels (BAX and BCL-2) were not different between groups.

Conclusions

ER stress contributes to the etiopathogenesis of adenoid tissue diseases and the pathogenesis of adenoid tissue disorders, which are part of the immune response. These results may guide the development of new and alternative treatments for immune system disorders.

[Blood-brain barrier breakdown and autoimmune cerebellar ataxia]

Autoimmune cerebellar ataxia is a disease entity that affects the cerebellum and is induced by autoimmune mechanisms. The disease is classified into several etiologies, including gluten ataxia, anti-glutamate decarboxylase (GAD) ataxia, paraneoplastic cerebellar degeneration, primary autoimmune cerebellar ataxia and postinfectious cerebellar ataxia. The autoimmune response in the periphery cross-reacts with similar antigens in the cerebellum due to molecular mimicry. Breakdown of the blood‒brain barrier (BBB) could potentially explain the vulnerability of the cerebellum during the development of autoimmune cerebellar ataxia, as it gives rise to the entry of pathogenic autoantibodies or lymphocytes into the cerebellum. In this review, the maintenance of the BBB under normal conditions and the molecular basis of BBB disruption under pathological conditions are highlighted. Next, the pathomechanism of BBB breakdown in each subtype of autoimmune cerebellar ataxia is discussed. We recently identified glucose-regulated protein (GRP) 78 antibodies in paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome, and GRP78 antibodies induced by cross-reactivity with tumors can disrupt the BBB and penetrate anti-P/Q type voltage-gated calcium channel (VGCC) antibodies into the cerebellum, thus leading to cerebellar ataxia in this disease.

Decoding contextual crosstalk: revealing distinct interactions between non-coding RNAs and unfolded protein response in breast cancer

Breast cancer is significantly influenced by endoplasmic reticulum (ER) stress, impacting both its initiation and progression. When cells experience an accumulation of misfolded or unfolded proteins, they activate the unfolded protein response (UPR) to restore cellular balance. In breast cancer, the UPR is frequently triggered due to challenging conditions within tumors. The UPR has a dual impact on breast cancer. On one hand, it can contribute to tumor growth by enhancing cell survival and resistance to programmed cell death in unfavorable environments. On the other hand, prolonged and severe ER stress can trigger cell death mechanisms, limiting tumor progression. Furthermore, ER stress has been linked to the regulation of non-coding RNAs (ncRNAs) in breast cancer cells. These ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play essential roles in cancer development by influencing gene expression and cellular processes. An improved understanding of how ER stress and ncRNAs interact in breast cancer can potentially lead to new treatment approaches. Modifying specific ncRNAs involved in the ER stress response might interfere with cancer cell survival and induce cell death. Additionally, focusing on UPR-associated proteins that interact with ncRNAs could offer novel therapeutic possibilities. Therefore, this review provides a concise overview of the interconnection between ER stress and ncRNAs in breast cancer, elucidating the nuanced effects of the UPR on cell fate and emphasizing the regulatory roles of ncRNAs in breast cancer progression.

Ferroptosis in cancer: From molecular mechanisms to therapeutic strategies

Ferroptosis is a non-apoptotic form of regulated cell death characterized by the lethal accumulation of iron-dependent membrane-localized lipid peroxides. It acts as an innate tumor suppressor mechanism and participates in the biological processes of tumors. Intriguingly, mesenchymal and dedifferentiated cancer cells, which are usually resistant to apoptosis and traditional therapies, are exquisitely vulnerable to ferroptosis, further underscoring its potential as a treatment approach for cancers, especially for refractory cancers. However, the impact of ferroptosis on cancer extends beyond its direct cytotoxic effect on tumor cells. Ferroptosis induction not only inhibits cancer but also promotes cancer development due to its potential negative impact on anticancer immunity. Thus, a comprehensive understanding of the role of ferroptosis in cancer is crucial for the successful translation of ferroptosis therapy from the laboratory to clinical applications. In this review, we provide an overview of the recent advancements in understanding ferroptosis in cancer, covering molecular mechanisms, biological functions, regulatory pathways, and interactions with the tumor microenvironment. We also summarize the potential applications of ferroptosis induction in immunotherapy, radiotherapy, and systemic therapy, as well as ferroptosis inhibition for cancer treatment in various conditions. We finally discuss ferroptosis markers, the current challenges and future directions of ferroptosis in the treatment of cancer.

Regulator of Ribosome Synthesis 1 (RRS1) Stabilizes GRP78 and Promotes Breast Cancer Progression

Regulator of ribosome synthesis 1 (RRS1), a crucial regulatory factor in ribosome biogenesis, exerts a remarkable impact on the progression of breast cancer (BC). However, the exact mechanisms and pathways have not yet been fully elucidated. To investigate the impact of RRS1 on BC growth and metastasis, along with its underlying mechanisms. We discovered that RRS1 is overexpressed in BC tissues and cell lines. This study aims to regulate the level of RRS1 through lentiviral transfection technology to explore its potential function in BC cells. Knockdown of RRS1 resulted in the inhibition of cell proliferation, invasion, and migration, whereas overexpression had the opposite effects. We firstly identified the interaction between RRS1 and Glucose-Regulated Protein 78 (GRP78) using Co-immunoprecipitation (Co-IP) combined with mass spectrometry analysis, providing evidences of co-localization and positive regulation between RRS1 and GRP78. We observed that RRS1 inhibited the degradation of GRP78 through the ubiquitin-proteasome pathway, resulting in the stabilization of GRP78. In addition, our findings suggested that RRS1 promoted BC progression by activating the GRP78-mediated phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. In conclusion, this newly discovered RRS1/GRP78 signaling axis provides a molecular and theoretical basis for further exploring the mechanisms of breast cancer invasion and metastasis.

Machine learning-based endoplasmic reticulum-related diagnostic biomarker and immune microenvironment landscape for osteoarthritis

BACKGROUND

Osteoarthritis (OA) is the most common degenerative joint disease worldwide. Further improving the current limited understanding of osteoarthritis has positive clinical value.

METHODS

OA samples were collected from GEO database and endoplasmic reticulum related genes (ERRGs) were identified. The WGCNA network was further built to identify the crucial gene module. Based on the expression profiles of characteristic ERRGs, LASSO algorithm was used to select key factors according to the minimum λ value. Random forest (RF) algorithm was used to calculate the importance of ERRGs. Subsequently, overlapping genes based on LASSO and RF algorithms were identified as ERRGs-related diagnostic biomarkers. In addition, OA specimens were also collected and performed qRT-PCR quantitative analysis of selected ERRGs.

RESULTS

We identified four ERRGs associated with OA risk assessment through machine learning methods, and verified the abnormal expressions of these screened markers in OA patients through in vitro experiments. The influence of selected markers on OA immune infiltration was also evaluated.

CONCLUSIONS

Our results provide new evidence for the role of ER stress in the OA progression, as well as new markers and potential intervention targets for OA.

N-Glycosylation as a Modulator of Protein Conformation and Assembly in Disease

Glycosylation, a prevalent post-translational modification, plays a pivotal role in regulating intricate cellular processes by covalently attaching glycans to macromolecules. Dysregulated glycosylation is linked to a spectrum of diseases, encompassing cancer, neurodegenerative disorders, congenital disorders, infections, and inflammation. This review delves into the intricate interplay between glycosylation and protein conformation, with a specific focus on the profound impact of N-glycans on the selection of distinct protein conformations characterized by distinct interactomes-namely, protein assemblies-under normal and pathological conditions across various diseases. We begin by examining the spike protein of the SARS virus, illustrating how N-glycans regulate the infectivity of pathogenic agents. Subsequently, we utilize the prion protein and the chaperone glucose-regulated protein 94 as examples, exploring instances where N-glycosylation transforms physiological protein structures into disease-associated forms. Unraveling these connections provides valuable insights into potential therapeutic avenues and a deeper comprehension of the molecular intricacies that underlie disease conditions. This exploration of glycosylation's influence on protein conformation effectively bridges the gap between the glycome and disease, offering a comprehensive perspective on the therapeutic implications of targeting conformational mutants and their pathologic assemblies in various diseases. The goal is to unravel the nuances of these post-translational modifications, shedding light on how they contribute to the intricate interplay between protein conformation, assembly, and disease.

Pentapeptide PYRAE triggers ER stress-mediated apoptosis of breast cancer cells in mice by targeting RHBDF1-BiP interaction

Reinforced cellular responses to endoplasmic reticulum (ER) stress are caused by a variety of pathological conditions including cancers. Human rhomboid family-1 protein (RHBDF1), a multiple transmembrane protein located mainly on the ER, has been shown to promote cancer development, while the binding immunoglobulin protein (BiP) is a key regulator of cellular unfolded protein response (UPR) for the maintenance of ER protein homeostasis. In this study, we investigated the role of RHBDF1 in maintaining ER protein homeostasis in breast cancer cells. We showed that deleting or silencing RHBDF1 in breast cancer cell lines MCF-7 and MDA-MB-231 caused marked aggregation of unfolded proteins in proximity to the ER. We demonstrated that RHBDF1 directly interacted with BiP, and this interaction had a stabilizing effect on the BiP protein. Based on the primary structural motifs of RHBDF1 involved in BiP binding, we found a pentapeptide (PE5) targeted BiP and inhibited BiP ATPase activity. SPR assay revealed a binding affinity of PE5 toward BiP (Kd = 57.7 μM). PE5 (50, 100, 200 μM) dose-dependently promoted ER protein aggregation and ER stress-mediated cell apoptosis in MCF-7 and MDA-MB-231 cells. In mouse 4T1 breast cancer xenograft model, injection of PE5 (10 mg/kg, s.c., every 2 days for 2 weeks) significantly inhibited the tumor growth with markedly increased ER stress and apoptosis-related proteins in tumor tissues. Our results suggest that the ability of RHBDF1 to maintain BiP protein stability is critical to ER protein homeostasis in breast cancer cells, and that the pentapeptide PE5 may serve as a scaffold for the development of a new class of anti-BiP inhibitors.

Targeting PAK4 reverses cisplatin resistance in NSCLC by modulating ER stress

Chemoresistance poses a significant impediment to effective treatments for non-small-cell lung cancer (NSCLC). P21-activated kinase 4 (PAK4) has been implicated in NSCLC progression by invasion and migration. However, the involvement of PAK4 in cisplatin resistance is not clear. Here, we presented a comprehensive investigation into the involvement of PAK4 in cisplatin resistance within NSCLC. Our study revealed enhanced PAK4 expression in both cisplatin-resistant NSCLC tumors and cell lines. Notably, PAK4 silencing led to a remarkable enhancement in the chemosensitivity of cisplatin-resistant NSCLC cells. Cisplatin evoked endoplasmic reticulum stress in NSCLC. Furthermore, inhibition of PAK4 demonstrated the potential to sensitize resistant tumor cells through modulating endoplasmic reticulum stress. Mechanistically, we unveiled that the suppression of the MEK1-GRP78 signaling pathway results in the sensitization of NSCLC cells to cisplatin after PAK4 knockdown. Our findings establish PAK4 as a promising therapeutic target for addressing chemoresistance in NSCLC, potentially opening new avenues for enhancing treatment efficacy and patient outcomes.

Nuclear GRP78 Promotes Metabolic Reprogramming and Therapeutic Resistance in Pancreatic Ductal Adenocarcinoma

PURPOSE

Stromal fibrosis limits nutritional supply and disarrays metabolism in pancreatic cancer (PDA, pancreatic ductal adenocarcinoma). Understanding of the molecular basis underlying metabolic cues would improve PDA management. The current study determined the interaction between glucose-regulated proteins 78 (GRP78) and hypoxia-inducible factor 1α (HIF-1α) and its mechanistic roles underlying PDA response to oxygen and glucose restrains.

EXPERIMENTAL DESIGN

Gene expression and its association with clinicopathologic characteristics of patients with PDA and mouse models were analyzed using IHC. Protein expression and their regulation were measured by Western blot and immunoprecipitation analyses. Protein interactions were determined using gain- and loss-of-function assays and molecular methods, including chromatin immunoprecipitation, co-immunoprecipitation, and dual luciferase reporter.

RESULTS

There was concomitant overexpression of both GRP78 and HIF-1α in human and mouse PDA tissues and cells. Glucose deprivation increased the expression of GRP78 and HIF-1α, particularly colocalization in nucleus. Induction of HIF-1α expression by glucose deprivation in PDA cells depended on the expression of and its own interaction with GRP78. Mechanistically, increased expression of both HIF-1α and LDHA under glucose deprivation was caused by the direct binding of GRP78 and HIF-1α protein complexes to the promoters of HIF-1α and LDHA genes and transactivation of their transcriptional activity.

CONCLUSIONS

Protein complex of GRP78 and HIF-1α directly binds to HIF-1α own promoter and LDHA promoter, enhances the transcription of both HIF-1α and LDHA, whereas glucose deprivation increases GRP78 expression and further enhances HIF-1α and LDHA transcription. Therefore, crosstalk and integration of hypoxia- and hypoglycemia-responsive signaling critically impact PDA metabolic reprogramming and therapeutic resistance.

Recent advances in small molecule and peptide inhibitors of glucose-regulated protein 78 for cancer therapy

Glucose-regulated protein 78 (GRP78) is one of key endoplasmic reticulum (ER) chaperone proteins that regulates the unfolded protein response (UPR) to maintain ER homeostasis. As a core factor in the regulation of the UPR, GRP78 takes a critical part in the cellular processes required for tumorigenesis, such as proliferation, metastasis, anti-apoptosis, immune escape and chemoresistance. Overexpression of GRP78 is closely correlated with tumorigenesis and poor prognosis in various malignant tumors. Targeting GRP78 is regarded as a potentially promising therapeutic strategy for cancer therapy. Although none of the GRP78 inhibitors have been approved to date, there have been several studies of GRP78 inhibitors. Herein, we comprehensively review the structure, physiological functions of GRP78 and the recent progress of GRP78 inhibitors, and discuss the structures, in vitro and in vivo efficacies, and merits and demerits of these inhibitors to inspire further research. Additionally, the feasibility of GRP78-targeting proteolysis-targeting chimeras (PROTACs), disrupting GRP78 cochaperone interactions, or covalent inhibition are also discussed as novel strategies for drugs discovery targeting GRP78, with the hope that these strategies can provide new opportunities for targeted GRP78 antitumor therapy.

ACE2-independent SARS-CoV-2 virus entry through cell surface GRP78 on monocytes - evidence from a translational clinical and experimental approach

BACKGROUND

SARS-CoV-2 infects host cells via an ACE2/TMPRSS2 entry mechanism. Monocytes and macrophages, which play a key role during severe COVID-19 express only low or no ACE2, suggesting alternative entry mechanisms in these cells. In silico analyses predicted GRP78, which is constitutively expressed on monocytes and macrophages, to be a potential candidate receptor for SARS-CoV-2 virus entry.

METHODS

Hospitalized COVID-19 patients were characterized regarding their pro-inflammatory state and cell surface GRP78 (csGRP78) expression in comparison to healthy controls. RNA from CD14+ monocytes of patients and controls were subjected to transcriptome analysis that was specifically complemented by bioinformatic re-analyses of bronchoalveolar lavage fluid (BALF) datasets of COVID-19 patients with a focus on monocyte/macrophage subsets, SARS-CoV-2 infection state as well as GRP78 gene expression. Monocyte and macrophage immunohistocytochemistry on GRP78 was conducted in post-mortem lung tissues. SARS-CoV-2 spike and GRP78 protein interaction was analyzed by surface plasmon resonance, GST Pull-down and Co-Immunoprecipitation. SARS-CoV-2 pseudovirus or single spike protein uptake was quantified in csGRP78high THP-1 cells.

FINDINGS

Cytokine patterns, monocyte activation markers and transcriptomic changes indicated typical COVID-19 associated inflammation accompanied by upregulated csGRP78 expression on peripheral blood and lung monocytes/macrophages. Subsequent cell culture experiments confirmed an association between elevated pro-inflammatory cytokine levels and upregulation of csGRP78. Interaction of csGRP78 and SARS-CoV-2 spike protein with a dissociation constant of KD = 55.2 nM was validated in vitro. Infection rate analyses in ACE2low and GRP78high THP-1 cells showed increased uptake of pseudovirus expressing SARS-CoV-2 spike protein.

INTERPRETATION

Our results demonstrate that csGRP78 acts as a receptor for SARS-CoV-2 spike protein to mediate ACE2-independent virus entry into monocytes.

FUNDING

Funded by the Sino-German-Center for Science Promotion (C-0040) and the Germany Ministry BMWi/K [DLR-grant 50WB1931 and RP1920 to AC, DM, TW].

Exploring the role of SWI/SNF complex subunit BAF60c in lipid metabolism and inflammation in fish

Chromatin remodeling plays an important role in regulating gene transcription, in which chromatin remodeling complex is a crucial aspect. Brg1/Brm-associated factor 60c (BAF60c) subunit forms a bridge between chromatin remodeling complexes and transcription factors in mammals; hence, it has received extensive attention. However, the roles of BAF60c in fish remain largely unexplored. In this study, we identified BAF60c-interacting proteins by using HIS-pull-down and LC-MS/MS analysis in fish. Subsequently, the RNA-seq analysis was performed to identify the overall effects of BAF60c. Then, the function of BAF60c was verified through BAF60c knockdown and overexpression experiments. We demonstrated for the first time that BAF60c interacts with glucose-regulated protein 78 (GRP78) and regulates lipid metabolism, endoplasmic reticulum (ER) stress, and inflammation. Knockdown of BAF60c reduces fatty acid biosynthesis, ER stress, and inflammation. In conclusion, the results enriched BAF60c-interacting protein network and explored the function of BAF60c in lipid metabolism and inflammation in fish.

Structural and functional complexity of HSP90 in cellular homeostasis and disease

Heat shock protein 90 (HSP90) is a chaperone with vital roles in regulating proteostasis, long recognized for its function in protein folding and maturation. A view is emerging that identifies HSP90 not as one protein that is structurally and functionally homogeneous but, rather, as a protein that is shaped by its environment. In this Review, we discuss evidence of multiple structural forms of HSP90 in health and disease, including homo-oligomers and hetero-oligomers, also termed epichaperomes, and examine the impact of stress, post-translational modifications and co-chaperones on their formation. We describe how these variations influence context-dependent functions of HSP90 as well as its interaction with other chaperones, co-chaperones and proteins, and how this structural complexity of HSP90 impacts and is impacted by its interaction with small molecule modulators. We close by discussing recent developments regarding the use of HSP90 inhibitors in cancer and how our new appreciation of the structural and functional heterogeneity of HSP90 invites a re-evaluation of how we discover and implement HSP90 therapeutics for disease treatment.

Transducin Beta-Like 2 is a Potential Driver Gene that Adapts to Endoplasmic Reticulum Stress to Promote Tumor Growth of Lung Adenocarcinoma

BACKGROUND

Endoplasmic reticulum (ER) stress has a close relation with cancer progression. Blocking the adaptive pathway of ER stress could be an anticancer strategy. Here, we identified an ER stress-related gene, Transducin beta-like 2 (TBL2), an ER-localized type I transmembrane protein, on increased chromosome 7q as a candidate driver gene of lung adenocarcinoma (LUAD).

METHODS

The association between TBL2 mRNA expression and prognostic outcomes and clinicopathological factors was analyzed using The Cancer Genome Atlas (TCGA) datasets of LUAD and lung squamous cell carcinoma (LUSC). Localization of TBL2 in tumor tissues was observed by immunohistochemical staining. Gene set enrichment analysis (GSEA) was conducted using TCGA dataset. In vitro cell proliferation assays were performed using TBL2 knockdown LUAD cells, LUSC cells, and LUAD cells overexpressing TBL2. Apoptosis and ATF4 expression (ER stress marker) were evaluated by western blotting.

RESULTS

TBL2 was overexpressed in LUAD and LUSC cells. Multivariate analysis indicated high TBL2 mRNA expression was an independent poor prognostic factor of LUAD. GSEA revealed high TBL2 expression was positively correlated to the ER stress response in LUAD. TBL2 knockdown attenuated LUAD cell proliferation under ER stress. TBL2 inhibited apoptosis in LUAD cells under ER stress. TBL2 knockdown reduced ATF4 expression under ER stress.

CONCLUSIONS

TBL2 may be a novel driver gene that facilitates cell proliferation, possibly by upregulating ATF4 expression followed by adaptation to ER stress, and it is a poor prognostic biomarker of LUAD.

The chaperone protein GRP78 released from MPN cells increases the expression of lysyl oxidase in a human stromal cell line

Impaired function of the endoplasmic stress (ER) response causes numerous pathological conditions, including tissue fibrosis. In the present study, we aimed to determine the pathological role of ER stress response systems in myeloproliferative neoplasms (MPNs). We found increased expression of the chaperone protein glucose-regulated protein (GRP) 78, a central regulator of ER stress, in megakaryocytes from primary myelofibrosis or postessential thrombocythemia myelofibrosis patients. GRP78 was overexpressed in JAK2V617F-harboring cell lines; however, inhibitors of ER stress did not affect the expression levels of GRP78. In contrast, ruxolitinib, a well-known inhibitor of JAK2V617F, clearly blocked GRP78 expression in these cells through downregulation of transcription factor 4 (ATF4). Interestingly, GRP78 was secreted from HEL and SET-2 cells into culture media. Coculture of these cells with HS-5 cells, a human bone marrow stroma-derived cell line, induced enhanced expression of lysyl oxidase (LOX), which mediates cross-linking of collagen fibers and induces tissue fibrosis, in HS-5 cells. An anti-GRP78 neutralizing antibody abrogated LOX elevation; in contrast, recombinant GRP78 protein induced LOX protein expression in HS-5 cells. Our observations suggest that the oncogenic protein JAK2V617F induces overexpression and release of GRP78, which may induce a fibrotic phenotype in surrounding bone marrow stromal cells.

Afzelin induces immunogenic cell death against lung cancer by targeting NQO2

BACKGROUND

Lung cancer is one of the most common malignant cancers worldwide. Previous studies have shown that Afzelin, a flavonoid, possesses anticancer activity. The aim of this study was to explore Afzelin's effect on lung cancer cells and delineate potential anti-cancer mechanism.

METHODS

The effect of Afzelin on cell viability, proliferation, and apoptosis of lung cancer cells i.e., A549 and H1299 cells, was studied. The targets for Afzelin in lung cancer were predicted using SwissTargetPrediction, Next, the GO analysis and pathway enrichment were analyzed using String. For in vitro studies, the overexpression plasmid of NQO2, the identified target of Afzelin, was transfected into Afzelin-treated cells to verify the regulatory role of Afzelin on its target and signaling pathway.

RESULTS

In in vitro studies, Afzelin markedly inhibited cell viability, proliferation, and raised apoptotic rate of A549 and H1299 cells. In addition, Afzelin activated endoplasmic reticulum (ER) stress and increased ATP, HMGB1, and CRT levels in lung cancer cells, indicating that Afzelin induced immunogenic cell death (ICD). SwissTargetPrediction identified NQO2 as a target of Afzelin. Further, Afzelin markedly inhibited NQO2 protein expression and in turn, overexpression of NQO2 attenuated the effect of Afzelin on A549 and H1299 cells.

CONCLUSION

Afzelin inhibits lung cancer progression by targeting NQO2, in turn, activating ER stress and inducing ICD.

Research progress on the GRP78 gene in the diagnosis, treatment and immunity of cervical cancer

BACKGROUND

GRP78 is a molecular chaperone protein in the endoplasmic reticulum that is involved in protein assembly and quality control, and it participates in ER stress regulation of endoplasmic reticulum stress pathways. Studies have confirmed that GRP78 gene is highly expressed in a variety of tumors and is involved in different biological functions.

PURPOSE

The present review highlights the involvement of the GRP78 gene in regulating the development of cervical cancer by promoting the proliferation and invasion of cervical cancer cells as well as by inhibiting apoptosis and promoting the Warburg effect. High expression of GRP78 is positively correlated with chemotherapy resistance in cervical cancer. GRP78 plays an anticancer role in cervical cancer by regulating autophagy and apoptosis. Mediated immune CD8 + T cells regulate tumor cell immunity and play a role in the application of the HPV vaccine.

CONCLUSIONS

GRP78 plays a multifunctional role in cervical cancer and has important therapeutic and diagnostic value.

NSUN2 is a glucose sensor suppressing cGAS/STING to maintain tumorigenesis and immunotherapy resistance

Glucose metabolism is known to orchestrate oncogenesis. Whether glucose serves as a signaling molecule directly regulating oncoprotein activity for tumorigenesis remains elusive. Here, we report that glucose is a cofactor binding to methyltransferase NSUN2 at amino acid 1-28 to promote NSUN2 oligomerization and activation. NSUN2 activation maintains global m5C RNA methylation, including TREX2, and stabilizes TREX2 to restrict cytosolic dsDNA accumulation and cGAS/STING activation for promoting tumorigenesis and anti-PD-L1 immunotherapy resistance. An NSUN2 mutant defective in glucose binding or disrupting glucose/NSUN2 interaction abolishes NSUN2 activity and TREX2 induction leading to cGAS/STING activation for oncogenic suppression. Strikingly, genetic deletion of the glucose/NSUN2/TREX2 axis suppresses tumorigenesis and overcomes anti-PD-L1 immunotherapy resistance in those cold tumors through cGAS/STING activation to facilitate apoptosis and CD8+ T cell infiltration. Our study identifies NSUN2 as a direct glucose sensor whose activation by glucose drives tumorigenesis and immunotherapy resistance by maintaining TREX2 expression for cGAS/STING inactivation.

HSP90B1-mediated plasma membrane localization of GLUT1 promotes radioresistance of glioblastomas

Ionizing radiation is a popular and effective treatment option for glioblastoma (GBM). However, resistance to radiation therapy inevitably occurs during treatment. It is urgent to investigate the mechanisms of radioresistance in GBM and to find ways to improve radiosensitivity. Here, we found that heat shock protein 90 beta family member 1 (HSP90B1) was significantly upregulated in radioresistant GBM cell lines. More importantly, HSP90B1 promoted the localization of glucose transporter type 1, a key rate-limiting factor of glycolysis, on the plasma membrane, which in turn enhanced glycolytic activity and subsequently tumor growth and radioresistance of GBM cells. These findings imply that targeting HSP90B1 may effectively improve the efficacy of radiotherapy for GBM patients, a potential new approach to the treatment of glioblastoma.

Prediction of prognosis and immune landscape in cervical cancer based on heat shock protein-related genes

Objective: Heat shock proteins (HSPs) play key roles in the malignant transformation and progression of many tumors. However, the effectiveness of using HSP-related genes to predict the prognosis of patients with cervical cancer (CC) remains elusive. We aimed to delineate the prognosis and biological significance of HSP-related genes in CC. Methods: We collected the transcriptional and clinical data of CC patients from The Cancer Genome Atlas (TCGA) and searched for HSP-related genes in the literature. LASSO and univariate/multivariate Cox regression analyses were utilized to screen genes; 12 genes were found to be related to CC survival, and a prediction model was built. The effectiveness of the model was confirmed using TCGA and GEO, and it was found to be an independent predictor of CC. The nomogram is plotted. The prognostic model was further visualized using calibration curves, which showed good agreement with the predicted outcomes at 1-, 3, and 5 years. Results: We found that low-risk patients had higher immune cell infiltration and stronger immune function, and according to the immunophenoscore and TIDE scores, the low-risk group tended to respond more to immunotherapy. Additionally, we used the GDSC database to predict drug sensitivity in patients with different prognostic risks. Conclusion: In summary, we built a good model to help predict the prognosis of CC patients and provide a reference for personalized treatment and medication for different patients.

Introduction of a new recombinant vaccine based on GRP78 for breast cancer immunotherapy and evaluation in a mouse model

Introduction

Breast cancer is one of the most prevalent malignancies in women. Several treatment options are available today, including surgery, chemotherapy, and radiotherapy. Immunotherapy, as a highly specific therapy, involves adaptive immune responses and immunological memory. In our present research, we used the recombinant C-terminal domain of the GRP78 (glucose- regulated protein 78) protein to induce an immune response and investigate its therapeutic impact in the 4T1 breast cancer model.

Methods

BALB/c mice were immunized with the cGRP78 protein. The humoral immune response was assessed by ELISA. Then, BALB/c mice were injected subcutaneously with 1×106 4T1 tumor cells. Subsequently, tumor size and survival rate measurements, MTT, and cytokine assays were performed.

Results

The animals receiving the cGRP78 vaccine showed significantly more favorable survival and slower tumor growth rates compared with unvaccinated tumor-bearing mice as the negative control mice. Circulating levels of tumoricidal cytokines such as IFNγ were higher, whereas tolerogenic cytokines such as IL-2, 6, and 10 either did not increase or had a decreasing trend in mice receiving cGRP78.

Conclusion

cGRP78 vaccines generated potent immunotherapeutic effects in a breast cancer mouse model. This novel strategy of targeting the GRP78 protein can promote the development of cancer vaccines and immunotherapies for breast cancer malignancies.

Tumor-associated macrophages confer colorectal cancer 5-fluorouracil resistance by promoting MRP1 membrane translocation via an intercellular CXCL17/CXCL22-CCR4-ATF6-GRP78 axis

Chemotherapy represents a major type of clinical treatment against colorectal cancer (CRC). Aberrant drug efflux mediated by transporters acts as a key approach for tumor cells to acquire chemotherapy resistance. Increasing evidence implies that tumor-associated macrophages (TAMs) play a pivotal role in both tumorigenesis and drug resistance. Nevertheless, the specific mechanism through which TAMs regulate drug efflux remains elusive. Here, we discovered that TAMs endow CRC cells with resistance to 5-fluorouracil (5-FU) treatment via a cell-cell interaction-mediated MRP1-dependent drug efflux process. Mechanistically, TAM-secreted C-C motif chemokine ligand 17 (CCL17) and CCL22, via membrane receptor CCR4, activated the PI3K/AKT pathway in CRC tumor cells. Specifically, phosphorylation of AKT inactivated IP3R and induced calcium aggregation in the ER, resulting in the activation of ATF6 and upregulation of GRP78. Accordingly, excessive GRP78 can interact with MRP1 and promote its translocation to the cell membrane, causing TAM-induced 5-FU efflux. Taken together, our results demonstrated that TAMs promote CRC chemotherapy resistance via elevating the expression of GRP78 to promote the membrane translocation of MRP1 and drug efflux, providing direct proof for TAM-induced drug resistance.

Unveiling the dark side of glucose-regulated protein 78 (GRP78) in cancers and other human pathology: a systematic review

Glucose-Regulated Protein 78 (GRP78) is a chaperone protein that is predominantly expressed in the lumen of the endoplasmic reticulum. GRP78 plays a crucial role in protein folding by assisting in the assembly of misfolded proteins. Under cellular stress conditions, GRP78 can translocate to the cell surface (csGRP78) were it interacts with different ligands to initiate various intracellular pathways. The expression of csGRP78 has been associated with tumor initiation and progression of multiple cancer types. This review provides a comprehensive analysis of the existing evidence on the roles of GRP78 in various types of cancer and other human pathology. Additionally, the review discusses the current understanding of the mechanisms underlying GRP78's involvement in tumorigenesis and cancer advancement. Furthermore, we highlight recent innovative approaches employed in downregulating GRP78 expression in cancers as a potential therapeutic target.

A nanotherapeutic approach to selectively eliminate metastatic breast cancer cells by targeting cell surface GRP78

Here, rational engineering of doxorubicin prodrug loaded peptide-targeted liposomal nanoparticles to selectively target metastatic breast cancer cells in vivo is described. Glucose-regulated protein 78 (GRP78), a heat shock protein typically localized in the endoplasmic reticulum in healthy cells, has been identified to home to the cell surface in certain cancers, and thus has emerged as a promising therapeutic target. Recent reports indicated GRP78 to be expressed on the cell surface of an aggressive subpopulation of stem-like breast cancer cells that exhibit metastatic potential. In this study, a targeted nanoparticle formulation with a GRP78-binding peptide (Kd of 7.4 ± 1.0 μM) was optimized to selectively target this subpopulation. In vitro studies with breast cancer cell lines showed the targeted nanoparticle formulation (TNPGRP78pep) achieved enhanced cellular uptake, while maintaining selectivity over the control groups. In vivo, TNPGRP78pep loaded with doxorubicin prodrug was evaluated using a lung metastatic mouse model and demonstrated inhibition of breast cancer cell seeding to lungs down at the level of negative control groups. Combined, this study established that specific-targeting of surface GRP78 expressing a subpopulation of aggressive breast cancer cells was able to inhibit breast cancer metastasis to lungs, and underpinned the significance of GRP78 in breast cancer metastasis.

The microenvironment dictates glycocalyx construction and immune surveillance

Efforts to identify anti-cancer therapeutics and understand tumor-immune interactions are built with in vitro models that do not match the microenvironmental characteristics of human tissues. Using in vitro models which mimic the physical properties of healthy or cancerous tissues and a physiologically relevant culture medium, we demonstrate that the chemical and physical properties of the microenvironment regulate the composition and topology of the glycocalyx. Remarkably, we find that cancer and age-related changes in the physical properties of the microenvironment are sufficient to adjust immune surveillance via the topology of the glycocalyx, a previously unknown phenomenon observable only with a physiologically relevant culture medium.

Antioxidant and Prooxidant Nanozymes: From Cellular Redox Regulation to Next-Generation Therapeutics

Nanozymes, nanomaterials with enzyme-mimicking activity, have attracted tremendous interest in recent years owing to their ability to replace natural enzymes in various biomedical applications, such as biosensing, therapeutics, drug delivery, and bioimaging. In particular, the nanozymes capable of regulating the cellular redox status by mimicking the antioxidant enzymes in mammalian cells are of great therapeutic significance in oxidative-stress-mediated disorders. As the distinction of physiological oxidative stress (oxidative eustress) and pathological oxidative stress (oxidative distress) occurs at a fine borderline, it is a great challenge to design nanozymes that can differentially sense the two extremes in cells, tissues and organs and mediate appropriate redox chemical reactions. In this Review, we summarize the advances in the development of redox-active nanozymes and their biomedical applications. We primarily highlight the therapeutic significance of the antioxidant and prooxidant nanozymes in various disease model systems, such as cancer, neurodegeneration, and cardiovascular diseases. The future perspectives of this emerging area of research and the challenges associated with the biomedical applications of nanozymes are described.

How aberrant N-glycosylation can alter protein functionality and ligand binding: An atomistic view

Protein-assembly defects due to an enrichment of aberrant conformational protein variants are emerging as a new frontier in therapeutics design. Understanding the structural elements that rewire the conformational dynamics of proteins and pathologically perturb functionally oriented ensembles is important for inhibitor development. Chaperones are hub proteins for the assembly of multiprotein complexes and an enrichment of aberrant conformers can affect the cellular proteome, and in turn, phenotypes. Here, we integrate computational and experimental tools to investigte how N-glycosylation of specific residues in glucose-regulated protein 94 (GRP94) modulates internal dynamics and alters the conformational fitness of regions fundamental for the interaction with ATP and synthetic ligands and impacts substructures important for the recognition of interacting proteins. N-glycosylation plays an active role in modulating the energy landscape of GRP94, and we provide support for leveraging the knowledge on distinct glycosylation variants to design molecules targeting GRP94 disease-associated conformational states and assemblies.

Role of the ER-induced UPR pathway, apoptosis, and autophagy in colorectal cancer

When large amounts of misfolded or unfolded proteins accumulate in the endoplasmic reticulum (ER) in response to stress, a process called unfolded protein response (UPR) is activated. The disruption of this process leads to many diseases including diabetes, neurodegenerative diseases, and many cancers. In the process of UPR in response to stress and unfolded proteins, specific signaling pathways are induced in the endoplasmic reticulum and subsequently transmitted to the nucleus and cytoplasm, causing homeostasis and restoring the cell's normal condition with reducing protein translation and synthesis. The UPR response followed by stress enhancement balances cell survival with death, therefore in this condition cells decide either to survive or have the path of apoptosis ahead. However, in some cases, this balance is disturbed and the UPR pathway is chronically activated or not activated and the cell conditions lead to cancer. This study aimed to briefly investigate the association between ER stress, UPR, apoptosis, and autophagy in colorectal cancer (CRC). Moreover, in current study, we will try to demonstrate canonical ways and methods for the treatment of CRC cells with attenuated ER stress.

ER chaperone GRP78/BiP translocates to the nucleus under stress and acts as a transcriptional regulator

Cancer cells are commonly subjected to endoplasmic reticulum (ER) stress. To gain survival advantage, cancer cells exploit the adaptive aspects of the unfolded protein response such as upregulation of the ER luminal chaperone GRP78. The finding that when overexpressed, GRP78 can escape to other cellular compartments to gain new functions regulating homeostasis and tumorigenesis represents a paradigm shift. Here, toward deciphering the mechanisms whereby GRP78 knockdown suppresses EGFR transcription, we find that nuclear GRP78 is prominent in cancer and stressed cells and uncover a nuclear localization signal critical for its translocation and nuclear activity. Furthermore, nuclear GRP78 can regulate expression of genes and pathways, notably those important for cell migration and invasion, by interacting with and inhibiting the activity of the transcriptional repressor ID2. Our study reveals a mechanism for cancer cells to respond to ER stress via transcriptional regulation mediated by nuclear GRP78 to adopt an invasive phenotype.

Aberrant LYZ expression in tumor cells serves as the potential biomarker and target for HCC and promotes tumor progression via csGRP78

Hepatocellular carcinoma (HCC) takes the predominant malignancy of hepatocytes with bleak outcomes owing to high heterogeneity among patients. Personalized treatments based on molecular profiles will better improve patients' prognosis. Lysozyme (LYZ), a secretory protein with antibacterial function generally expressed in monocytes/macrophages, has been observed for the prognostic implications in different types of tumors. However, studies about the explicit applicative scenarios and mechanisms for tumor progression are still quite limited, especially for HCC. Here, based on the proteomic molecular classification data of early-stage HCC, we revealed that the LYZ level was elevated significantly in the most malignant HCC subtype and could serve as an independent prognostic predictor for HCC patients. Molecular profiles of LYZ-high HCCs were typical of those for the most malignant HCC subtype, with impaired metabolism, along with promoted proliferation and metastasis characteristics. Further studies demonstrated that LYZ tended to be aberrantly expressed in poorly differentiated HCC cells, which was regulated by STAT3 activation. LYZ promoted HCC proliferation and migration in both autocrine and paracrine manners independent of the muramidase activity through the activation of downstream protumoral signaling pathways via cell surface GRP78. Subcutaneous and orthotopic xenograft tumor models indicated that targeting LYZ inhibited HCC growth markedly in NOD/SCID mice. These results propose LYZ as a prognostic biomarker and therapeutic target for the subclass of HCC with an aggressive phenotype.

Bone and the Unfolded Protein Response: In Sickness and in Health

Differentiation and optimal function of osteoblasts and osteoclasts are contingent on synthesis and maintenance of a healthy proteome. Impaired and/or altered secretory capacity of these skeletal cells is a primary driver of most skeletal diseases. The endoplasmic reticulum (ER) orchestrates the folding and maturation of membrane as well as secreted proteins at high rates within a calcium rich and oxidative organellar niche. Three ER membrane proteins monitor fidelity of protein processing in the ER and initiate an intricate signaling cascade known as the Unfolded Protein Response (UPR) to remediate accumulation of misfolded proteins in its lumen, a condition referred to as ER stress. The UPR aids in fine-tuning, expanding and/or modifying  the cellular proteome, especially in specialized secretory cells, to match everchanging physiologic cues and metabolic demands. Sustained activation of the UPR due to chronic ER stress, however, is known to hasten cell death and drive pathophysiology of several diseases. A growing body of evidence suggests that ER stress and an aberrant UPR may contribute to poor skeletal health and the development of osteoporosis. Small molecule therapeutics that target distinct components of the UPR may therefore have implications for developing novel treatment modalities relevant to the skeleton. This review summarizes the complexity of UPR actions in bone cells in the context of skeletal physiology and osteoporotic bone loss, and highlights the need for future mechanistic studies to develop novel UPR therapeutics that mitigate adverse skeletal outcomes.

HSPA5 Promotes Attachment and Internalization of Porcine Epidemic Diarrhea Virus through Interaction with the Spike Protein and the Endo-/Lysosomal Pathway

Porcine epidemic diarrhea virus (PEDV) has caused huge economic losses to the global pig industry. The swine enteric coronavirus spike (S) protein recognizes various cell surface molecules to regulate viral infection. In this study, we identified 211 host membrane proteins related to the S1 protein by pulldown combined with liquid-chromatography tandem mass spectrometry (LC-MS/MS) analysis. Among these, heat shock protein family A member 5 (HSPA5) was identified through screening as having a specific interaction with the PEDV S protein, and positive regulation of PEDV infection was validated by knockdown and overexpression tests. Further studies verified the role of HSPA5 in viral attachment and internalization. In addition, we found that HSPA5 interacts with S proteins through its nucleotide-binding structural domain (NBD) and that polyclonal antibodies can block viral infection. In detail, HSPA5 was found to be involved in viral trafficking via the endo-/lysosomal pathway. Inhibition of HSPA5 activity during internalization would reduce the subcellular colocalization of PEDV with lysosomes in the endo-/lysosomal pathway. Together, these findings show that HSPA5 is a novel PEDV potential target for the creation of therapeutic drugs. IMPORTANCE PEDV infection causes severe piglet mortality and threatens the global pig industry. However, the complex invasion mechanism of PEDV makes its prevention and control difficult. Here, we determined that HSPA5 is a novel target for PEDV which interacts with its S protein and is involved in viral attachment and internalization, influencing its transport via the endo-/lysosomal pathway. Our work extends knowledge about the relationship between the PEDV S and host proteins and provides a new therapeutic target against PEDV infection.

Cell surface GRP78: a potential mechanism of therapeutic resistant tumors

GRP78 is a protein that acts as a chaperone within the endoplasmic reticulum (ER) and has multiple functions. It is induced by stress and abets cells from survival. Despite, multiple Stress conditions like ER, chronic psychological and nutritional stress, hypoxia, chemotherapy, radiation therapy, and drug resistance induce cell surface GRP78 (CS-GRP78) expression in cancer cells. Further, CS-GRP78 is associated with increased malignancy and resistance to anti-cancer therapies and is considered a high-value druggable target. Recent preclinical research suggests that targeting CS-GRP78 with anti-GRP78 monoclonal antibodies (Mab) in combination with other agents may be effective in reversing the failure of chemotherapy, radiotherapy, or targeted therapies and increasing the efficacy of solid tumors treatment. This article will review recent evidence on the role of CS-GRP78 in developing resistance to anti-cancer treatments and the potential benefits of combining anti-GRP78 Mab with other cancer therapies for specific patient populations. Furthermore, our limited understanding of how CS-GRP78 regulated in human studies is a major drawback for designing effective CS-GRP78-targeted therapies. Hence, more research is still warranted to translate these potential therapies into clinical applications.

HSPA5, as a ferroptosis regulator, may serve as a potential therapeutic for head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a ferroptosis sensitive tumor type with high mortality rate. However, it remains largely unknown whether ferroptosis influences the tumor cell in HNSCC.

MATERIALS AND METHODS

To investigate how ferroptosis regulators were differentially expressed between normal and tumor tissue, data related to HNSCC was downloaded from The Cancer Genome Atlas. The expression levels of key factors in HNSCC and the relationship between key factors and ferroptosis in HNSCC were conducted in vitro, and then analyzed to correlate with the differences in prognosis and survival. This was then combined with TNM staging data, and the migration effects of key factors in HNSCC were verified by scratch test and transwell test.

RESULTS

In this study, gene expression analysis and correlation studies between genes showed that HSPA5 was a potentially key associated ferroptosis regulator in HNSCC. Bioinformatics analysis showed that high expression of HSPA5 in HNSCC was positively correlated with poor prognosis and distal metastasis of HNSCC. In vitro immunohistochemistry and western blot tests confirmed that HSPA5 was highly expressed in HNSCC tissues and cell lines. In vitro inhibition of HSPA5 reduced the viability of HNSCC cells and increased ferroptosis. The results of scratch, transwell, and immunofluorescence tests showed that HSPA5 was related to the migration of HNSCC. In addition, a pan-cancer analysis showed that HSPA5 was also overexpressed in many types of cancer with poor prognoses.

CONCLUSION

In total, our study demonstrates the critical role of ferroptosis regulators in HNSCC and that HSPA5, as a ferroptosis regulator, can be regarded as a key molecular target for designing new therapeutic regimens to control HNSCC metastasis and progression.

GRP78 Inhibitor YUM70 Suppresses SARS-CoV-2 Viral Entry, Spike Protein Production and Ameliorates Lung Damage

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the COVID-19 pandemic, has given rise to many new variants with increased transmissibility and the ability to evade vaccine protection. The 78-kDa glucose-regulated protein (GRP78) is a major endoplasmic reticulum (ER) chaperone that has been recently implicated as an essential host factor for SARS-CoV-2 entry and infection. In this study, we investigated the efficacy of YUM70, a small molecule inhibitor of GRP78, to block SARS-CoV-2 viral entry and infection in vitro and in vivo. Using human lung epithelial cells and pseudoviral particles carrying spike proteins from different SARS-CoV-2 variants, we found that YUM70 was equally effective at blocking viral entry mediated by original and variant spike proteins. Furthermore, YUM70 reduced SARS-CoV-2 infection without impacting cell viability in vitro and suppressed viral protein production following SARS-CoV-2 infection. Additionally, YUM70 rescued the cell viability of multi-cellular human lung and liver 3D organoids transfected with a SARS-CoV-2 replicon. Importantly, YUM70 treatment ameliorated lung damage in transgenic mice infected with SARS-CoV-2, which correlated with reduced weight loss and longer survival. Thus, GRP78 inhibition may be a promising approach to augment existing therapies to block SARS-CoV-2, its variants, and other viruses that utilize GRP78 for entry and infection.

Relevance of serum levels of the endoplasmic reticulum stress protein GRP78 (glucose-regulated protein 78 kDa) as biomarker in pulmonary diseases

Cellular stress and inflammation contribute to the initiation and progression of a variety of pulmonary diseases. Endoplasmic reticulum (ER) stress and its main regulator GRP78 (glucose-regulated protein 78 kDa) appear to be involved in the pathogenesis of pulmonary diseases, and GRP78 was found to be a biomarker in a wide range of inflammatory diseases. The aim of this study was to investigate the relevance of serum GRP78 in pulmonary disorders.In this prospective cohort study, 78 consecutive patients with chronic obstructive pulmonary disease (COPD, n = 28), asthma (n = 38) or interstitial lung disease (ILD, n = 12) underwent measurement of serum GRP78 levels by ELISA.The mean age of patients was 59.8 ± 12.4 years, 48.7% were female. Patients with elevated GRP78 levels (> median) offered a significantly better oxygenation status (capillary pO2: 75.3 ± 11.7 mmHg vs. 67.8 ± 15.9 mmHg, p = 0.02). Significant correlations were observed between GRP78, on the one hand, and haemoglobin, high-sensitivity C-reactive protein (hs-CRP) and eosinophil counts, on the other hand (haemoglobin: Pearson's r = -0.25, hs-CRP: r = 0.30, eosinophils: r = 0.63).Subsequently, we evaluated GRP78 measurements in function of severity stratifiers of the specific underlying pulmonary disease. ILD patients with a severe diffusion impairment (DLCO< 40% of predicted), exhibited a significant decrease in GRP78 levels (p = 0.01). In COPD and asthma, both characterized by obstructive ventilatory defects, a forced expiratory volume in one second (FEV1) <30% of predicted was accompanied by significantly lower GRP78 (p = 0.0075).In both obstructive and restrictive pulmonary disorders, GRP78 protein concentrations were reduced with increasing disease severity. These data suggest a prevalent role of GRP78 in the presently studied pulmonary disorders.

Secretome Screening of BRAFV600E-Mutated Colon Cancer Cells Resistant to Vemurafenib

Patients with metastatic colorectal cancer (mCRC) carrying BRAFV600E mutation have worse response to chemotherapy and poor prognosis. The BRAFV600E inhibitor vemurafenib has shown modest efficacy as monotherapy in BRAF-mutated mCRC due to the development of resistance. The aim of this study was to conduct a comparative proteomics profiling of the secretome from vemurafenib-sensitive vs. -resistant colon cancer cells harboring BRAFV600E mutation in order to identify specific secretory features potentially associated with changes in the resistant cells' phenotype. Towards this aim, we employed two complementary proteomics approaches including two-dimensional gel electrophoresis coupled with MALDI-TOF/TOF mass spectrometry and label-free quantitative LC-MS/MS analysis. Obtained results pointed to aberrant regulation of DNA replication and endoplasmic reticulum stress as the major secretome features associated with chemoresistant phenotype. Accordingly, two proteins implicated in these processes including RPA1 and HSPA5/GRP78 were discussed in more details in the context of biological networks and their importance as potential secretome targets for further functional and clinical evaluation. Expression patterns of RPA1 and HSPA5/GRP78 in tumor tissues from colon cancer patients were also found in additional in silico analyses to be associated with BRAFV600E mutation status, which opens the possibility to extrapolate our findings and their clinical implication to other solid tumors harboring BRAFV600E mutation, such as melanoma.