Unfolding anti-tumor immunity: ER stress responses sculpt tolerogenic myeloid cells in cancer

Diagnostic and predictive significance of the ferroptosis-related gene TXNIP in lung adenocarcinoma stem cells based on multi-omics

BACKGROUND

Lung cancer stands as the foremost cause of cancer-related fatalities globally. The presence of cancer stem cells (CSCs) poses a challenge, rendering current targeted tumor therapies ineffective. This study endeavors to investigate a novel therapeutic approach focusing on ferroptosis and delves into the expression of ferroptosis-related genes within lung CSCs.

METHODS

We systematically examined RNA-seq datasets derived from lung tumor cells (LTCs) and lung cancer stem cells (LSCs), as previously investigated in our research. Our focus was on analyzing differentially expressed genes (DEGs) related to ferroptosis. Utilizing the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO), we conducted functional analysis of these ferroptosis-related DEGs. Additionally, we employed protein‒protein interaction networks to identify hub genes. LC‒MS/MS analysis of LTCs and LSCs was conducted to pinpoint the crucial ferroptosis-related gene-thioredoxin-interacting protein (TXNIP).Further, we delved into the immune cell infiltration landscape of LTCs and LSCs, examining the correlation between TXNIP and lung adenocarcinoma (LUAD) using data from The Cancer Genome Atlas (TCGA) database. To complement these findings, we measured the expression levels of TXNIP, glutathione peroxidase 4(GPX4), nuclear receptor coactivator 4 (NCOA4) in LUAD tissues through immunohistochemistry (IHC) staining.

RESULTS

A total of 651 DEGs were identified, with 17 of them being ferroptosis-related DEGs. These seventeen genes were categorized into four groups: driver genes, suppressor genes, unclassified genes, and inducer genes. Enrichment analysis revealed significant associations with oxidative stress, cell differentiation, tissue development, and cell death processes. The RNA-seq analysis demonstrated consistent gene expression patterns with protein expression, as evidenced by mass spectrometry analysis. Among the identified genes, SFN and TXNIP were singled out as hub genes, with TXNIP showing particularly noteworthy expression. The expression of the ferroptosis-related gene TXNIP exhibited correlations with the presence of an immunosuppressive microenvironment, TNM stages, and the degree of histological differentiation.Also, the ferroptosis-markers GPX4 and NCOA4 displayed correlations with LUAD. This comprehensive analysis underscores the significance of TXNIP in the context of ferroptosis-related processes and their potential implications in cancer development and progression.

CONCLUSION

The investigation conducted in this study systematically delved into the role of the ferroptosis-related gene TXNIP in Lung CSCs. The identification of TXNIP as a potentially valuable biomarker in this context could have significant implications for refining prognostic assessments and optimizing therapeutic strategies for advanced lung cancer.

Unveiling the Role of Endoplasmic Reticulum Stress Pathways in Canine Demodicosis

Canine demodicosis is a prevalent skin disease caused by overpopulation of a commensal species of Demodex mite, yet its precise cause remains unknown. Research suggests that T-cell exhaustion, increased immunosuppressive cytokines, induction of regulatory T cells and increased expression of immune checkpoint inhibitors may contribute to its pathogenesis. This study aimed to gain a deeper understanding of the molecular changes occurring in canine demodicosis using mass spectrometry and pathway enrichment analysis. The results indicate that endoplasmic reticulum stress promotes canine demodicosis through regulation of three linked signalling pathways: eIF2, mTOR, and eIF4 and p70S6K. These pathways are involved in the modulation of Toll-like receptors, most notably TLR2, and have been shown to play a role in the pathogenesis of skin diseases in both dogs and humans. Moreover, these pathways are also implicated in the promotion of immunosuppressive M2 phenotype macrophages. Immunohistochemical analysis, utilising common markers of dendritic cells and macrophages, verified the presence of M2 macrophages in canine demodicosis. The proteomic analysis also identified immunological disease, organismal injury and abnormalities and inflammatory response as the most significant underlying diseases and disorders associated with canine demodicosis. This study demonstrates that Demodex mites, through ER stress, unfolded protein response and M2 macrophages contribute to an immunosuppressive microenvironment, thereby assisting in their proliferation.

Reinforced Immunogenic Endoplasmic Reticulum Stress and Oxidative Stress via an Orchestrated Nanophotoinducer to Boost Cancer Photoimmunotherapy

Cancer progression and treatment-associated cellular stress impairs therapeutic outcome by inducing resistance. Endoplasmic reticulum (ER) stress is responsible for core events. Aberrant activation of stress sensors and their downstream components to disrupt homeostasis have emerged as vital regulators of tumor progression as well as response to cancer therapy. Here, an orchestrated nanophotoinducer (ERsNP) results in specific tumor ER-homing, induces hyperthermia and mounting oxidative stress associated reactive oxygen species (ROS), and provokes intense and lethal ER stress upon near-infrared laser irradiation. The strengthened "dying" of ER stress and ROS subsequently induce apoptosis for both primary and abscopal B16F10 and GL261 tumors, and promote damage-associated molecular patterns to evoke stress-dependent immunogenic cell death effects and release "self-antigens". Thus, there is a cascade to activate maturation of dendritic cells, reprogram myeloid-derived suppressor cells to manipulate immunosuppression, and recruit cytotoxic T lymphocytes and effective antitumor response. The long-term protection against tumor recurrence is realized through cascaded combinatorial preoperative and postoperative photoimmunotherapy including the chemokine (C-C motif) receptor 2 antagonist, ERsNP upon laser irradiation, and an immune checkpoint inhibitor. The results highlight great promise of the orchestrated nanophotoinducer to exert potent immunogenic cell stress and death by reinforcing ER stress and oxidative stress to boost cancer photoimmunotherapy.

Stress granules and hormetic adaptation of cancer

Cell stress is inherent to cancer and a key driver of tumorigenesis. Recent studies have proposed that cell stress promotes tumorigenesis through non-membranous organelles known as stress granules (SGs). While the biology of SGs is an emerging field, all studies to date point to the enhanced ability of cancer cells to form SGs compared with normal cells, a heightened dependence on SGs for survival under adverse conditions and for chemotherapy resistance, and the dependence of tumors on SGs for growth. Why cancer cells become dependent on SGs and how SGs promote tumorigenesis remain to be elucidated. Here, we attempt to provide a framework for answering these questions by framing SGs as a hormetic response to tumor-associated stress stimuli.

TMPRSS11D/ALR-mediated ER stress regulates the function of myeloid-derived suppressor cells in the cervical cancer microenvironment

Myeloid-derived suppressor cells (MDSCs) contribute to tumor immune evasion, and have been identified as immunosuppressive cells in cervical cancer. The effect of TMPRSS11D (transmembrane serine protease 11D) in some cancers has been reported, but its role in immune escape of cervical cancer is still unclear. This study aims to elucidate the regulatory mechanism of TMPRSS11D on the immunosuppressive function of MDSCs in cervical cancer. Our data showed that the proportion of polymorphonucleoid MDSCs (PMN-MDSCs), the contents of immunosuppressive factors (including INOS, IDO, and ARG-1) secreted by MDSCs, and TMPRSS11D mRNA level in peripheral blood mononuclear cells (PBMCs) of malignant cervical cancer patients was significantly higher than that of benign tumor patients. Next, CD3+ T cells from PBMCs of cervical cancer patients were stimulated with anti-CD3 and anti-CD28, and then co-cultured with PMN-MDSCs from the same donors at a ratio of 1:2 for 3 days. PMN-MDSCs from malignant tumors produced more ROS, while TMPRSS11D knockdown blocked ROS production. PMN-MDSCs inhibited T cell proliferation and IFN-γ production, while silencing TMPRSS11D in PMN-MDSCs hindered the immunosuppressive effect of PMN-MDSCs. Mechanistically, TMPRSS11D bound to ALR (Augmenter of liver regeneration) and negatively regulated ALR expression, inducing ER stress in PMN-MDSCs, thereby enhancing the immunosuppressive effect of PMN-MDSCs on T cells. Additionally, mouse xenograft tumor assay was conducted to assess the role of TMPRSS11D in tumor growth and MDSC accumulation in vivo. Silencing TMPRSS11D impeded the growth of cervical cancer xenografts and reduced the accumulation of MDSCs in tumor tissues. In conclusion, TMPRSS11D induced ER stress in MDSCs through negative regulation of ALR, thus enhancing the immunosuppressive effect of MDSCs on T cells, so as to promote the growth of cervical cancer tumors.

The recent progress of myeloid-derived suppressor cell and its targeted therapies in cancers

Myeloid-derived suppressor cells (MDSCs) are an immature group of myeloid-derived cells generated from myeloid cell precursors in the bone marrow. MDSCs appear almost exclusively in pathological conditions, such as tumor progression and various inflammatory diseases. The leading function of MDSCs is their immunosuppressive ability, which plays a crucial role in tumor progression and metastasis through their immunosuppressive effects. Since MDSCs have specific molecular features, and only a tiny amount exists in physiological conditions, MDSC-targeted therapy has become a promising research direction for tumor treatment with minimal side effects. In this review, we briefly introduce the classification, generation and maturation process, and features of MDSCs, and detail their functions under various circumstances. The present review specifically demonstrates the environmental specificity of MDSCs, highlighting the differences between MDSCs from cancer and healthy individuals, as well as tumor-infiltrating MDSCs and circulating MDSCs. Then, we further describe recent advances in MDSC-targeted therapies. The existing and potential targeted drugs are divided into three categories, monoclonal antibodies, small-molecular inhibitors, and peptides. Their targeting mechanisms and characteristics have been summarized respectively. We believe that a comprehensive in-depth understanding of MDSC-targeted therapy could provide more possibilities for the treatment of cancer.

LINP1 represses unfolded protein response by directly inhibiting eIF2α phosphorylation to promote cutaneous squamous cell carcinoma

BACKGROUND

Endoplasmic reticulum stress (ER stress) may destroy endoplasmic reticulum homeostasis (ER homeostasis) and leads to programmable cell death. Unfolded protein response (UPR) originally stimulated by ER stress is critical for the survival of tumor cells through trying to re-establish ER homeostasis as an adaption to harsh microenvironment. However, mechanisms involving key regulators in modulating UPR remain underexplored.

METHODS

The expression of LINP1 in cutaneous squamous cell carcinoma (cSCC) tissues and cell lines was assessed. Subsequently, LINP1 was knocked out, knocked down or overexpressed in cSCC cells. CCK-8 assays, colony forming assays, transwell migration assays and invasiveness measurement by matrigel-coated transwell were performed to examine the role of LINP1 in cSCC development through gain-of-function and loss-of-function experiments. Transcriptomic sequencing (RNA-Seq) was conducted and indicated the key downstream signaling events regulated by LINP1 including UPR and apoptosis signaling. Furthermore, the direct interaction between LINP1 and eIF2α to modulate UPR and apoptosis was confirmed by RNA pulldown, RNA immunoprecipitation (RIP), ChIP-qPCR and in vitro phosphorylation assays.

RESULTS

In this study, LncRNA in non-homologous end joining pathway 1 (LINP1) was identified to be one of the top ten highest-expressed LncRNAs in cSCC, the second most common cancer in the world. Functional studies using in vitro and in vivo models revealed that LINP1 functions as an oncogene to promote cell proliferation, colony formation, migration and invasiveness while inhibiting cell apoptosis in cSCC. Transcriptomic sequencing after knockdown of LINP1 indicated LINP1 negatively regulates UPR-related pathways involving key effectors for activating UPR and the apoptosis following the prolonged UPR. Mechanistic study showed LINP1 physically interacts with eIF2α to inhibit its phosphorylation for avoiding unmitigated UPR. Loss of LINP1 followed by enhanced eIF2α phosphorylation led to overactivated UPR and induced DDIT3 expression, contributing to ER stress-induced apoptosis and suppression of cSCC development.

CONCLUSIONS

Our findings demonstrate a novel regulatory hierarchy of UPR by demonstrating LINP1 as a critical modulator for eIF2α phosphorylation and a suppressor of UPR-mediated apoptosis, which suggests a novel therapeutic target for cSCC treatment.

MSX1 Regulates Goat Endometrial Function by Altering the Plasma Membrane Transformation of Endometrial Epithelium Cells during Early Pregnancy

MSX1 is an important member of the muscle segment homeobox gene (Msh) family and acts as a transcription factor to regulate tissue plasticity, yet its role in goat endometrium remodeling remains elusive. In this study, an immunohistochemical analysis showed that MSX1 was mainly expressed in the luminal and glandular epithelium of goat uterus, and the MSX1 expression was upregulated in pregnancy at days 15 and 18 compared with pregnancy at day 5. In order to explore its function, goat endometrial epithelial cells (gEECs) were treated with 17 β-estrogen (E₂), progesterone (P₄), and/or interferon-tau (IFNτ), which were used to mimic the physiological environment of early pregnancy. The results showed that MSX1 was significantly upregulated with E₂- and P₄-alone treatment, or their combined treatment, and IFNτ further enhanced its expression. The spheroid attachment and PGE2/PGF2α ratio were downregulated by the suppression of MSX1. The combination of E₂, P₄, and IFNτ treatment induced the plasma membrane transformation (PMT) of gEECs, which mainly showed the upregulation of N-cadherin (CDH2) and concomitant downregulation of the polarity-related genes (ZO-1, α-PKC, Par3, Lgl2, and SCRIB). The knockdown of MSX1 partly hindered the PMT induced by E₂, P₄, and IFNτ treatment, while the upregulation of CDH2 and the downregulation of the partly polarity-related genes were significantly enhanced when MSX1 was overexpressed. Moreover, MSX1 regulated the CDH2 expression by activating the endoplasmic reticulum (ER) stress-mediated unfolded protein response (UPR) pathway. Collectively, these results suggest that MSX1 was involved in the PMT of the gEECs through the ER stress-mediated UPR pathway, which affects endometrial adhesion and secretion function.

HSPB8 facilitates prostate cancer progression via activating the JAK/STAT3 signaling pathway

Prostate cancer (PC) is a clinically and biologically heterogeneous disease that lacks effective treatment. Heat shock protein B8 (HSPB8) is an important factor in the progression of various types of cancer. However, the clinical significance and biological role of HSPB8 in PC are still unclear. In this study, we determined HSPB8 expression in PC tissues by immunohistochemical staining and explored the in vitro functions of HSPB8 using HSPB8 knockdown DU145 and LNcap PC cell lines. The in vivo effect of HSPB8 was explored by a subcutaneous xenograft mice model. The human phospho-kinase array and signal transducer and activator of transcription (STAT) 3 activator were utilized to explore the potential mechanism of HSPB8-induced PC progression. As a result, we found that HSPB8 was abundantly expressed in PC tissues and cell lines. HSPB8 knockdown inhibited cell proliferation and migration, promoted apoptosis and cycle repression, as well as weakened tumorigenesis ability. Mechanistically, we demonstrated that HSPB8 facilitates the malignant phenotypes of PC by activating the Janus kinase/STAT3 signaling pathway. These results proposed that HSPB8 seems to be an attractive therapeutic target for PC patients.

Endoplasmic reticulum stress mediates the myeloid-derived immune suppression associated with cancer and infectious disease

Myeloid-derived suppressor cells (MDSCs), which are immature heterogeneous bone marrow cells, have been described as potent immune regulators in human and murine cancer models. The distribution of MDSCs varies across organs and is divided into three subpopulations: granulocytic MDSCs or polymorphonuclear MDSCs (G-MDSCs or PMN-MDSCs), monocytic MDSCs (M-MDSCs), as well as a recently identified early precursor MDSC (eMDSCs) in humans. Activated MDSCs induce the inactivation of NK cells, CD4+, and CD8+ T cells through a variety of mechanisms, thus promoting the formation of tumor immunosuppressive microenvironment. ER stress plays an important protecting role in the survival of MDSC, which aggravates the immunosuppression in tumors. In addition, ferroptosis can promote an anti-tumor immune response by reversing the immunosuppressive microenvironment. This review summarizes immune suppression by MDSCs with a focus on the role of endoplasmic reticulum stress-mediated immune suppression in cancer and infectious disease, in particular leprosy and tuberculosis.

From targeted therapy to a novel way: Immunogenic cell death in lung cancer

Lung cancer (LC) is one of the most incident malignancies and a leading cause of cancer mortality worldwide. Common tumorigenic drivers of LC mainly include genetic alterations of EGFR, ALK, KRAS, BRAF, ROS1, and MET. Small inhibitory molecules and antibodies selectively targeting these alterations or/and their downstream signaling pathways have been approved for treatment of LC. Unfortunately, following initial positive responses to these targeted therapies, a large number of patients show dismal prognosis due to the occurrence of resistance mechanisms, such as novel mutations of these genes and activation of alternative signaling pathways. Over the past decade, it has become clear that there is no possible cure for LC unless potent antitumor immune responses are induced by therapeutic intervention. Immunogenic cell death (ICD) is a newly emerged concept, a form of regulated cell death that is sufficient to activate adaptive immune responses against tumor cells. It transforms dying cancer cells into a therapeutic vaccine and stimulates long-lasting protective antitumor immunity. In this review, we discuss the key targetable genetic aberrations and the underlying mechanism of ICD in LC. Various agents inducing ICD are summarized and the possibility of harnessing ICD in LC immunotherapy is further explored.

Therapy sculpts the complex interplay between cancer and the immune system during tumour evolution

Cancer development is an evolutionary process. A key selection pressure is exerted by therapy, one of the few players in cancer evolution that can be controlled. As such, an understanding of how treatment acts to sculpt the tumour and its microenvironment and how this influences a tumour's subsequent evolutionary trajectory is critical. In this review, we examine cancer evolution and intra-tumour heterogeneity in the context of therapy. We focus on how radiotherapy, chemotherapy and immunotherapy shape both tumour development and the environment in which tumours evolve and how resistance can develop or be selected for during treatment.

ER stress-related mRNA-lncRNA co-expression gene signature predicts the prognosis and immune implications of esophageal cancer

BACKGROUND

Esophageal cancer (EC) is one of the most common malignant cancers in the world. Endoplasmic reticulum (ER) stress is an adaptive response to various stress conditions and has been implicated in the development of various types of cancer. Long noncoding RNAs (lncRNAs) refer to a group of noncoding RNAs (ncRNAs), which regulate gene expression by interacting with DNA, RNA and proteins. Accumulating evidence suggests that lncRNAs are critical regulators of gene expression in development, differentiation, and human diseases, such as cancers and heart diseases. However, the prognostic model of EC based on ER stress-related mRNA and lncRNA has not been reported.

METHODS

Firstly, we downloaded RNA expression profiles from The Cancer Genome Atlas (TCGA) and obtained ER stress-related genes from the Molecular Signature Database (MSigDB). Next, Weighted Correlation Network Analysis (WGCNA) co-expression analysis was used to identify survival-related ER stress-related modules. Prognostic models were developed using univariate and Least absolute shrinkage and selection operator (LASSO) regression analyses on the training set and validated on the test set. Afterwards, The Receiver Operating Characteristic (ROC) curve and nomogram were used to evaluate the performance of risk prediction models. Differentially expressed gene (DEG) and enrichment analysis were performed between different groups in order to identify the biological processes correlated with the risk score. Finally, the fraction of immune cell infiltration and the difference of tumor microenvironment were identified in high-risk and low-risk groups.

RESULTS

The WGCNA co-expression analysis identified 49 ER genes that are highly associated with EC prognosis. Using univariate Cox regression and LASSO regression analysis, we developed prognostic risk models based on nine signature genes (four mRNAs and five lncRNAs). Both in the training and in the test sets, the overall survival (OS) of EC patients in the high-risk group was significantly lower than that in the low-risk group. The Kaplan-Meier curve and the ROC curve demonstrate the prognostic model we built can precisely predict the survival with more than 70% accuracy. The correlation analysis between the risk score and the infiltration of immune cells showed that the model can indicate the state of the immune microenvironment in EC.

CONCLUSION

In this study, we developed a novel prognostic model for esophageal cancer based on ER stress-related mRNA-lncRNA co-expression profiles that could predict the prognosis, immune cell infiltration, and immunotherapy response in patients with EC. Our results also may provide clinicians with a quantitative tool to predict the survival time of patients and help them individualize treatment strategies for the patients with EC.

Zearalenone Induces Apoptosis in Porcine Endometrial Stromal Cells through JNK Signaling Pathway Based on Endoplasmic Reticulum Stress

Zearalenone (ZEA) is an estrogen-like mycotoxin characterized mainly by reproductive toxicity, to which pigs are particularly sensitive. The aim of this study was to investigate the molecular mechanism of ZEA-induced apoptosis in porcine endometrial stromal cells (ESCs) by activating the JNK signaling pathway through endoplasmic reticulum stress (ERS). In this study, ESCs were exposed to ZEA, with the ERS inhibitor sodium 4-Phenylbutyrate (4-PBA) as a reference. The results showed that ZEA could damage cell structures, induce endoplasmic reticulum swelling and fragmentation, and decreased the ratio of live cells to dead cells significantly. In addition, ZEA could increase reactive oxygen species and Ca²⁺ levels; upregulate the expression of GRP78, CHOP, PERK, ASK1 and JNK; activate JNK phosphorylation and its high expression in the nucleus; upregulate the expression Caspase 3 and Caspase 9; and increase the Bax/Bcl-2 ratio, resulting in increased apoptosis. After 3 h of 4-PBA-pretreatment, ZEA was added for mixed culture, which showed that the inhibition of ERS could reduce the cytotoxicity of ZEA toward ESCs. Compared with the ZEA group, ERS inhibition increased cell viability; downregulated the expression of GRP78, CHOP, PERK, ASK1 and JNK; and decreased the nuclear level of p-JNK. The Bax/Bcl-2 ratio and the expression of Caspase 3 and Caspase 9 were downregulated, significantly alleviating apoptosis. These results demonstrate that ZEA can alter the morphology of ESCs, destroy their ultrastructure, and activate the JNK signaling via the ERS pathway, leading to apoptosis.

Ablation of the endoplasmic reticulum stress kinase PERK induces paraptosis and type I interferon to promote anti-tumor T cell responses

Activation of unfolded protein responses (UPRs) in cancer cells undergoing endoplasmic reticulum (ER) stress promotes survival. However, how UPR in tumor cells impacts anti-tumor immune responses remains poorly described. Here, we investigate the role of the UPR mediator pancreatic ER kinase (PKR)-like ER kinase (PERK) in cancer cells in the modulation of anti-tumor immunity. Deletion of PERK in cancer cells or pharmacological inhibition of PERK in melanoma-bearing mice incites robust activation of anti-tumor T cell immunity and attenuates tumor growth. PERK elimination in ER-stressed malignant cells triggers SEC61β-induced paraptosis, thereby promoting immunogenic cell death (ICD) and systemic anti-tumor responses. ICD induction in PERK-ablated tumors stimulates type I interferon production in dendritic cells (DCs), which primes CCR2-dependent tumor trafficking of common-monocytic precursors and their intra-tumor commitment into monocytic-lineage inflammatory Ly6C+CD103+ DCs. These findings identify how tumor cell-derived PERK promotes immune evasion and highlight the potential of PERK-targeting therapies in cancer immunotherapy.

Roles of organelle-specific autophagy in hepatocytes in the development and treatment of non-alcoholic fatty liver disease

ABSTRACT

Non-alcoholic fatty liver disease (NAFLD) is a disorder of lipid metabolism. The lipotoxic intermediates of lipid metabolism cause mitochondrial dysfunction and endoplasmic reticulum stress. Organelle-specific autophagy is responsible for the removal of dysfunctional organelles to maintain intracellular homeostasis. Lipophagy contributes to lipid turnover by degrading lipid droplets. The level of autophagy changes during the course of NAFLD, and the activation of hepatocyte autophagy might represent a method of treating NAFLD.

Myeloid-derived suppressor cells in hematologic malignancies: two sides of the same coin

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of bone marrow cells originating from immature myeloid cells. They exert potent immunosuppressive activity and are closely associated with the development of various diseases such as malignancies, infections, and inflammation. In malignant tumors, MDSCs, one of the most dominant cellular components comprising the tumor microenvironment, play a crucial role in tumor growth, drug resistance, recurrence, and immune escape. Although the role of MDSCs in solid tumors is currently being extensively studied, little is known about their role in hematologic malignancies. In this review, we comprehensively summarized and reviewed the different roles of MDSCs in hematologic malignancies and hematopoietic stem cell transplantation, and finally discussed current targeted therapeutic strategies.Affiliation: Kindly check and confirm the processed affiliations are correct. Amend if any.correct

Downregulation of Low-density lipoprotein receptor-related protein 1B (LRP1B) inhibits the progression of hepatocellular carcinoma cells by activating the endoplasmic reticulum stress signaling pathway

Hepatocellular carcinoma (HCC) has a high recurrence rate and mortality rate even after surgery. Low-density lipoprotein receptor-related protein 1B (LRP1B) has proven to be involved in tumor development and progression of multiple malignancies. However, the function of LRP1B in HCC progression has not been fully elucidated. Thus, we conducted this study to explore the relationship between LRP1B and HCC. Bioinformatic analyses implied that LRP1B was highly expressed in HCC tissues. High LRP1B expression was shown to be related to poor outcomes and the determination of HCC patients’ tumor stage. LRP1B deletion impeded the proliferation, migration, and invasion of HCC cells. Further investigation demonstrated that silencing LRP1B expression enhanced the sensitivity of HCC cells to doxorubicin. LRP1B deletion inhibited HCC progression by regulating the PERK-ATF4-CHOP signaling pathway. Additionally, we probed the genomic alterations of LRP1B in HCC and the impact on the prognosis of patients. Collectively, our results suggest that LRP1B plays an essential role in the promotion of HCC progression by regulating the PERK-ATF4-CHOP signaling pathway, which is a potential prognostic biomarker and a promising therapeutic target of HCC.

Unfolded Protein Response Is Activated by Aurora Kinase A in Esophageal Adenocarcinoma

Unfolded protein response (UPR) protects malignant cells from endoplasmic reticulum stress-induced apoptosis. We report that Aurora kinase A (AURKA) promotes cancer cell survival by activating UPR in esophageal adenocarcinoma (EAC). A strong positive correlation between AURKA and binding immunoglobulin protein (BIP) mRNA expression levels was found in EACs. The in vitro assays indicated that AURKA promoted IRE1α protein phosphorylation, activating prosurvival UPR in FLO-1 and OE33 cells. The use of acidic bile salts to mimic reflux conditions in patients induced high AURKA and IRE1α levels. This induction was abrogated by AURKA knockdown in EAC cells. AURKA and p-IRE1α protein colocalization was observed in neoplastic gastroesophageal lesions of the L2-IL1b mouse model of Barrett's esophageal neoplasia. The combined treatment using AURKA inhibitor and tunicamycin synergistically induced cancer cell death. The use of alisertib for AURKA inhibition in the EAC xenograft model led to a decrease in IRE1α phosphorylation with a significant reduction in tumor growth. These results indicate that AURKA activates UPR, promoting cancer cell survival during ER stress in EAC. Targeting AURKA can significantly reverse prosurvival UPR signaling mechanisms and decrease cancer cell survival, providing a promising approach for the treatment of EAC patients.

Long noncoding RNA Gas5 induces cell apoptosis and inhibits tumor growth via activating the CHOP-dependent endoplasmic reticulum stress pathway in human hepatoblastoma HepG2 cells

In recent years, long noncoding RNAs (lncRNAs) have been demonstrated to be important tumor-associated regulatory factors. LncRNA growth arrest-specific transcript 5 (Gas5) acts as an anti-oncogene in most cancers. Whether Gas5 acts as an oncogene or anti-oncogene in hepatocellular carcinoma (HCC) remains unclear. In the present study, the expression and role of Gas5 in HCC were investigated in vitro and in vivo. Lower expression levels of Gas5 were determined in HCC tissues and cells by quantitative reverse transcription-polymerase chain reaction. Overexpressed Gas 5 lentiviral vectors were constructed to analyze their influence on cell viability, migration, invasion, and apoptosis. Fluorescence in situ hybridization was used to identify the subcellular localization of Gas5. Protein complexes that bound to Gas5 were isolated from HepG2 cells through pull-down experiments and analyzed by mass spectrometry. A series of novel Gas5-interacting proteins were identified and bioinformatics analysis was carried out. These included ribosomal proteins, proteins involved in protein folding, sorting, and transportation in the ER, some nucleases and protein enzymes involved in gene transcription, translation, and other proteins with various functions.78 kDa glucose-regulated protein (GRP78) was identified as a direct target of Gas5 by Rip-qPCR and Western blot analysis assay. Gas5 inhibited HepG2 cell growth and induced cell apoptosis via upregulating CHOP to activate the ER stress signaling pathway. Further studies indicated that the knockdown of CHOP by shRNA partially reversed Gas5-mediated apoptosis in HepG2 cells. Magnetic resonance imaging showed that the ectopic expression of Gas5 inhibited the growth of HCC in nude mice. These findings suggest that Gas5 functions as a tumor suppressor and induces apoptosis through activation of ER stress by targeting the CHOP signal pathway in HCC.

Controlling Immunoregulatory Cell Activity for Effective Photodynamic Therapy of Cancer

Recently, it has become clear that a prerequisite requirement for most cancer therapies is controlling the negative impact of the activity of immunosuppressory cell populations. It is therefore of a considerable interest to develop treatments for containing the operation of major myeloid and lymphoid immunoregulatory cell populations. We have reported that acid ceramidase inhibitor LCL521 effectively overrides the activity of immunoregulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) engaged in the context of tumor response to photodynamic therapy (PDT). The present communication dissects and describes in detail the procedure for the use of LCL521 as an adjuvant to PDT for improved cure rates of treated tumors based on restricting the activity of immunoregulatory cell populations.

Myeloid-Derived Suppressor Cells in Prostate Cancer: Present Knowledge and Future Perspectives

Several lines of research are being investigated to better understand mechanisms implicated in response or resistance to immune checkpoint blockade in prostate cancer (PCa). Myeloid-derived suppressor cells (MDSCs) have emerged as a major mediator of immunosuppression in the tumor microenvironment that promotes progression of various tumor types. The main mechanisms underlying MDSC-induced immunosuppression are currently being explored and strategies to enhance anti-tumor immune response via MDSC targeting are being tested. However, the role of MDSCs in PCa remains elusive. In this review, we aim to summarize and present the state-of-the-art knowledge on current methodologies to phenotypically and metabolically characterize MDSCs in PCa. We describe how these characteristics may be linked with MDSC function and may influence the clinical outcomes of patients with PCa. Finally, we briefly discuss emerging strategies being employed to therapeutically target MDSCs and potentiate the long-overdue improvement in the efficacy of immunotherapy in patients with PCa.

A common approach for fighting tuberculosis and leprosy: controlling endoplasmic reticulum stress in myeloid-derived suppressor cells

Leprosy and tuberculosis are infectious diseases that are caused by bacteria, and both share primary risk factors. Mediators of these diseases are regulated by a heterogeneous immature population of myeloid cells called myeloid-derived suppressor cells (MDSCs) that exhibit immunosuppressive activity against innate and adaptive immunity. During pathological conditions, endoplasmic reticulum (ER) stress occurs in MDSCs, and high levels of ER stress affect MDSC-linked immunosuppressive activity. Investigating the role of ER stress in regulating immunosuppressive functions of MDSCs in leprosy and tuberculosis may lead to new approaches to treating these diseases. Here the authors discuss the immunoregulatory effects of ER stress in MDSCs as well as the possibility of targeting unfolded protein response elements of ER stress to diminish the immunosuppressive activity of MDSCs and reinvigorate diminished adaptive immune system responses that occur in leprosy and tuberculosis.

Proteomic signatures of myeloid derived suppressor cells from liver and lung metastases reveal functional divergence and potential therapeutic targets

Myeloid-derived suppressor cells (MDSCs) promote immunosuppressive activities in the tumor microenvironment (TME), resulting in increased tumor burden and diminishing the anti-tumor response of immunotherapies. While primary and metastatic tumors are typically the focal points of therapeutic development, the immune cells of the TME are differentially programmed by the tissue of the metastatic site. In particular, MDSCs are programmed uniquely within different organs in the context of tumor progression. Given that MDSC plasticity is shaped by the surrounding environment, the proteomes of MDSCs from different metastatic sites are hypothesized to be unique. A bottom-up proteomics approach using sequential window acquisition of all theoretical mass spectra (SWATH-MS) was used to quantify the proteome of CD11b⁺ cells derived from murine liver metastases (LM) and lung metastases (LuM). A comparative proteomics workflow was employed to compare MDSC proteins from LuM (LuM-MDSC) and LM (LM-MDSC) while also elucidating common signaling pathways, protein function, and possible drug-protein interactions. SWATH-MS identified 2516 proteins from 200 µg of sample. Of the 2516 proteins, 2367 have matching transcriptomic data. Upregulated proteins from lung and liver-derived murine CD11b⁺ cells with matching mRNA transcriptomic data were categorized based on target knowledge and level of drug development. Comparative proteomic analysis demonstrates that liver and lung tumor-derived MDSCs have distinct proteomes that may be subject to pharmacologic manipulation.

Therapeutic Approaches Targeting Proteostasis in Kidney Disease and Fibrosis

Pathological insults usually disturb the folding capacity of cellular proteins and lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER), which leads to so-called “ER stress”. Increasing evidence indicates that ER stress acts as a trigger factor for the development and progression of many kidney diseases. The unfolded protein responses (UPRs), a set of molecular signals that resume proteostasis under ER stress, are thought to restore the adaptive process in chronic kidney disease (CKD) and renal fibrosis. Furthermore, the idea of targeting UPRs for CKD treatment has been well discussed in the past decade. This review summarizes the up-to-date literature regarding studies on the relationship between the UPRs, systemic fibrosis, and renal diseases. We also address the potential therapeutic possibilities of renal diseases based on the modulation of UPRs and ER proteostasis. Finally, we list some of the current UPR modulators and their therapeutic potentials.

Role of the Inflammatory Response of RAW 264.7 Cells in the Metastasis of Novel Cancer Stem-Like Cells

Background and objectives: Tumor progression and the immune response are intricately linked. Additionally, the presence of macrophages in the microenvironment is essential for carcinogenesis, but regulation of the polarization of M1- and M2-like macrophages and their role in metastasis remain unclear. Based on previous studies, both reactive oxygen species (ROS) and the endoplasmic reticulum (ER) are emerging as key players in macrophage polarization. While it is known that cancers alter macrophage inflammatory responses to promote tumor progression, there is limited knowledge regarding how they affect the macrophage-dependent innate host defense. Materials and methods: We detected the levels of ROS, the ability of chemotaxis, the expressions of markers of M1-/M2-like macrophages in RAW264.7 in presence of T2- and T2C-conditioned medium. Results: The results of this study indicated that ROS levels were decreased in RAW 264.7 cells when cultured with T2C-conditioned medium, while there was an improvement in chemotaxis abilities. We also found that the M2-like macrophages were characterized by an elongated shape in RAW 264.7 cells cultured in T2C-conditioned medium, which had increased CD206 expression but decreased expression of CD86 and inducible nitric oxide synthase. Suppression of ER stress shifted polarized M1-like macrophages toward an M2-like phenotype in RAW 264.7 cells cultured in T2C-conditioned medium. Conclusions: Taken together, we conclude that the polarization of macrophages is associated with the alteration of cell shape, ROS accumulation, and ER stress.

Modulation of cell physiology under hypoxia in pancreatic cancer

In solid tumors, the development of vasculature is, to some extent, slower than the proliferation of the different types of cells that form the tissue, both cancer and stroma cells. As a consequence, the oxygen availability is compromised and the tissue evolves toward a condition of hypoxia. The presence of hypoxia is variable depending on where the cells are localized, being less extreme at the periphery of the tumor and more severe in areas located deep within the tumor mass. Surprisingly, the cells do not die. Intracellular pathways that are critical for cell fate such as endoplasmic reticulum stress, apoptosis, autophagy, and others are all involved in cellular responses to the low oxygen availability and are orchestrated by hypoxia-inducible factor. Oxidative stress and inflammation are critical conditions that develop under hypoxia. Together with changes in cellular bioenergetics, all contribute to cell survival. Moreover, cell-to-cell interaction is established within the tumor such that cancer cells and the microenvironment maintain a bidirectional communication. Additionally, the release of extracellular vesicles, or exosomes, represents short and long loops that can convey important information regarding invasion and metastasis. As a result, the tumor grows and its malignancy increases. Currently, one of the most lethal tumors is pancreatic cancer. This paper reviews the most recent advances in the knowledge of how cells grow in a pancreatic tumor by adapting to hypoxia. Unmasking the physiological processes that help the tumor increase its size and their regulation will be of major relevance for the treatment of this deadly tumor.

ER-Phagy: A New Regulator of ER Homeostasis

The endoplasmic reticulum (ER) is one of the most important cellular organelles and is essential for cell homeostasis. Upon external stimulation, ER stress induces the unfolded protein response (UPR) and ER-associated degradation (ERAD) to maintain ER homeostasis. However, persistent ER stress can lead to cell damage. ER-phagy is a selective form of autophagy that ensures the timely removal of damaged ER, thereby protecting cells from damage caused by excessive ER stress. As ER-phagy is a newly identified form of autophagy, many receptor-mediated ER-phagy pathways have been discovered in recent years. In this review, we summarize our understanding of the maintenance of ER homeostasis and describe the receptors identified to date. Finally, the relationships between ER-phagy and diseases are also discussed.

IRE1α Expedites the Progression of Castration-Resistant Prostate Cancers via the Positive Feedback Loop of IRE1α/IL-6/AR

Castration-resistant prostate cancer (CRPC) is the lethal form of prostate cancer (PCa), and the underlying molecular mechanism has not been fully elucidated. Inositol requiring enzyme 1 alpha (IRE1α), a key regulator of unfolded protein response (UPR), is intimately associated with PCa progression. However, whether IRE1α is implicated in CRPC development remains unknown. Here, we showed that IRE1α expression was significantly increased in CRPC tissues and high-grade PCa tissues. Overexpression of IRE1α promoted PCa cell proliferation under the androgen deficiency condition in vitro and in vivo. Mechanistically, increased IRE1α expression induced IL-6 secretion via the IRE1α/XBP-1s signal pathway. IRE1α-induced IL-6 activated androgen receptor (AR), and the activation of AR by IL-6, in turn, promoted IRE1α expression. IRE1α formed a positive feedback loop with IL-6 and AR to promote prostate cancer cell proliferation under the androgen-deficient condition. In clinical PCa samples, high IRE1α expression correlated with elevated IL-6 and increased PSA expression. Our findings demonstrated a novel mechanism of CRPC progression and suggest targeting IRE1α may be a potential target for the prevention and treatment of CRPC.

Asiatic Acid Induces Endoplasmic Reticulum Stress and Activates the Grp78/IRE1α/JNK and Calpain Pathways to Inhibit Tongue Cancer Growth

Asiatic acid (AA) has been shown to induce apoptotic death in a range of cancers, but the mechanisms whereby it can inhibit tongue cancer growth have yet to be clarified. Herein, we explored the effects of AA on tongue cancer cells and found that it induced their apoptotic death in vitro and in vivo, while additionally impairing xenograft tumor growth in vivo. From a mechanistic perspective, AA treatment was associated with increases in levels of calcium and the calcium- dependent protease calpain, and it further induced endoplasmic reticulum (ER) stress and consequent Grp78-related IRE1α and JNK phosphorylation, ultimately driving caspase-3 activation and apoptotic death. Together, these results highlight AA as a promising tool for the therapeutic treatment of tongue cancer in clinical practice.

Tumor-related stress regulates functional plasticity of MDSCs

Myeloid-derived suppressor cells (MDSCs) impair protective anti-tumor immunity and remain major obstacles that stymie the effectiveness of promising cancer therapies. Diverse tumor-derived stressors galvanize the differentiation, intra-tumoral expansion, and immunomodulatory function of MDSCs. These tumor-associated 'axes of stress' underwrite the immunosuppressive programming of MDSCs in cancer and contribute to the phenotypic/functional heterogeneity that characterize tumor-MDSCs. This review discusses various tumor-associated axes of stress that direct MDSC development, accumulation, and immunosuppressive function, as well as current strategies aimed at overcoming the detrimental impact of MDSCs in cancer. To better understand the constellation of signals directing MDSC biology, we herein summarize the pivotal roles, signaling mediators, and effects of reactive oxygen/nitrogen species-related stress, chronic inflammatory stress, hypoxia-linked stress, endoplasmic reticulum stress, metabolic stress, and therapy-associated stress on MDSCs. Although therapeutic targeting of these processes remains mostly pre-clinical, intercepting signaling through the axes of stress could overcome MDSC-related immune suppression in tumor-bearing hosts.

Novel Combinatorial Approaches to Tackle the Immunosuppressive Microenvironment of Prostate Cancer

Prostate cancer (PCa) is the second-most common cancer in men worldwide and treatment options for patients with advanced or aggressive prostate cancer or recurrent disease continue to be of limited success and are rarely curative. Despite immune checkpoint blockade (ICB) efficacy in some melanoma, lung, kidney and breast cancers, immunotherapy efforts have been remarkably unsuccessful in PCa. One hypothesis behind this lack of efficacy is the generation of a distinctly immunosuppressive prostate tumor microenvironment (TME) by regulatory T cells, MDSCs, and type 2 macrophages which have been implicated in a variety of pathological conditions including solid cancers. In PCa, Tregs and MDSCs are attracted to TME by low-grade chronic inflammatory signals, while tissue-resident type 2 macrophages are induced by cytokines such as IL4, IL10, IL13, transforming growth factor beta (TGFβ) or prostaglandin E2 (PGE2) produced by Th2 cells. These then drive tumor progression, therapy resistance and the generation of castration resistance, ultimately conferring a poor prognosis. The biology of MDSC and Treg is highly complex and the development, proliferation, maturation or function can each be pharmacologically mediated to counteract the immunosuppressive effects of these cells. Herein, we present a critical review of Treg, MDSC and M2 involvement in PCa progression but also investigate a newly recognized type of immune suppression induced by the chronic stimulation of the sympathetic adrenergic signaling pathway and propose targeted strategies to be used in a combinatorial modality with immunotherapy interventions such as ICB, Sipuleucel-T or antitumor vaccines for an enhanced anti-PCa tumor immune response. We conclude that a strategic sequence of therapeutic interventions in combination with additional holistic measures will be necessary to achieve maximum benefit for PCa patients.

Endoplasmic Reticulum Stress Is Involved in Glucocorticoid-Induced Apoptosis in PC12 Cells

Objective

The present study selected PC12 cells to construct a neuronal injury model induced by glucocorticoids (GC) in vitro, aiming to explore whether the endoplasmic reticulum stress (ERS) PKR-like endoplasmic reticulum kinase (PERK)-activating transcription factor 4 (ATF4)-C/EBP-homologous protein (CHOP) and inositol requirement 1 (IRE1)-apoptosis signal regulating kinase 1 (ASK1)-C-Jun amino-terminal kinase (JNK) signaling pathways are associated with the neuronal injury process induced by GC and provide morphological evidence.

Methods

Cell models with different doses and different durations of GC exposure were established. The viability of PC12 cells was detected by the CCK-8 assay, and the apoptosis rate of PC12 cells was detected by the flow cytometry assay. The expression of microtubule-associated protein 2 (Map2); glucocorticoids receptor (GR); cellular oncogene fos (C-fos); and ERS-related proteins, glucose-regulated protein 78 (GRP78), p-PERK, p-IRE1, ATF4, ASK1, JNK, and CHOP, was observed by immunofluorescence staining.

Results

The results of immunofluorescence staining showed that PC12 cells abundantly expressed Map2 and GR. The CCK-8 assay revealed that high-concentration GC exposure significantly inhibited the cell viability of PC12 cells. The flow cytometry assay indicated that high-concentration GC exposure significantly increased the apoptosis rate of PC12 cells. Immunofluorescence staining showed that GC exposure significantly increased the expression of C-fos, GRP78, p-PERK, p-IRE1, ATF4, ASK1, JNK, and CHOP. Treatment with ERS inhibitor 4-phenylbutyric acid (4-PBA) and GR inhibitor RU38486 attenuated related damage and downregulated the expression of the abovementioned proteins.

Conclusion

High-concentration GC exposure can significantly inhibit the viability of PC12 cells and induce apoptosis. PERK-ATF4-CHOP and IRE1-ASK1-JNK pathways are involved in the above damage process.

PGE2 Released by Pancreatic Cancer Cells Undergoing ER Stress Transfers the Stress to DCs Impairing Their Immune Function

This study shows that pancreatic cancer cells undergoing cell death by valproic acid (VPA) treatment activated dendritic cells (DCs) more efficiently than those treated with trichostatin A (TSA), as demonstrated by CD86 and CD80 surface expression. Surprisingly though, DCs cultured in the presence of supernatant derived from VPA-treated cancer cells showed a reduced allostimulatory capacity and an increased release of IL10 and IL8 cytokines in comparison with those exposed to TSA-treated cell culture supernatant. Searching for molecular mechanisms leading to such differences, we found that VPA treatment dysregulated choline metabolism and triggered a stronger endoplasmic reticulum (ER) stress in pancreatic cancer cells than TSA, upregulating CCAAT/enhancer-binding protein homologous protein, and activated cyclooxygenase-2, thus promoting the release of prostaglandin (PG) E2. Interestingly, dysfunctional DCs cultured in the presence of VPA-treated cells culture supernatant showed a higher level of intracellular reactive oxygen species, 4-hydroxy-trans-2-nonenal protein adducts, and ER stress, as evidenced by the upregulation of spliced X-box binding protein 1 (XBP1s), effects that were reduced when DCs were exposed to supernatant of cancer cells treated with Celecoxib before VPA. Celecoxib prevented PGE2 release, restoring the function of DCs exposed to VPA-treated cells culture supernatant, and a similar effect was obtained by silencing XBP1s in DCs treated with VPA-treated cells culture supernatant. These results suggest that PGE2 could be one of the yet unidentified factors able to transfer the stress from cancer cells to DCs, resulting in an impairment of their function.

Metabolism of Dendritic Cells in Tumor Microenvironment: For Immunotherapy

Dendritic cells (DCs) are a type of an antigen-presenting cell which undertake a job on capturing antigens coming from pathogens or tumors and presenting to T cells for immune response. The metabolism of DCs controls its development, polarization, and maturation processes and provides energy support for its functions. However, the immune activity of DCs in tumor microenvironment (TME) is inhibited generally. Abnormal metabolism of tumor cells causes metabolic changes in TME, such as hyperglycolysis, lactate and lipid accumulation, acidification, tryptophan deprivation, which limit the function of DCs and lead to the occurrence of tumor immune escape. Combined metabolic regulation with immunotherapy can strengthen the ability of antigen-presentation and T cell activation of DCs, improve the existing anti-tumor therapy, and overcome the defects of DC-related therapies in the current stage, which has great potential in oncology therapy. Therefore, we reviewed the glucose, lipid, and amino acid metabolism of DCs, as well as the metabolic changes after being affected by TME. Together with the potential metabolic targets of DCs, possible anti-tumor therapeutic pathways were summarized.

The Pathology of Morphine-Inhibited Nerve Repair and Morphine-Induced Nerve Damage Is Mediated via Endoplasmic Reticulum Stress

Objective

The aim of the present study was to observe the pathological damage in the cerebral cortex of rats under acute morphine exposure (AME) and different durations of morphine dependence (MD), explore whether endoplasmic reticulum stress (ERS) is involved in the damage process, and assess the effect of morphine exposure on the proliferation and differentiation of newborn neurons.

Methods

Rat models of AME and different durations of MD were established. Pathological changes in cortical neurons were assessed by hematoxylin and eosin (H&E) and thionine staining. The expression of nuclear receptor-related factor 1 (NURR1) and that of the ERS-related proteins glucose-regulated protein 78 (GRP78), p-eIF2α, activating transcription factor 6 (ATF6), and CHOP in cortical neurons was assessed by immunohistochemistry. Double immunofluorescence labeling was used to observe the expression of Ki-67.

Results

H&E and thionine staining revealed that AME resulted in pyknotic changes in cortical neurons. With prolonged morphine exposure, the number of pyknotic neurons was significantly increased, the protein expression of Ki-67 and NURR1 was significantly decreased, and the protein levels of GRP78, p-eIF2α, ATF6, and CHOP showed marked dynamic changes.

Conclusion

AME and different durations of MD caused varying degrees of pathological changes in the cortex. Furthermore, the dynamic changes observed in ERS-related protein expression suggested that ERS may be associated with cortical injury. Different durations of MD inhibited the proliferation, differentiation, and migration of newborn neurons, which may affect the nerve repair process after injury.

Scutebarbatine A induces cytotoxicity in hepatocellular carcinoma via activation of the MAPK and ER stress signaling pathways

Scutebarbatine A (SBT-A), a diterpenoid alkaloid found in the root of Scutellaria barbata D. Don, has been reported to induce the apoptosis of A549 cells. In this study, we investigated the antitumor activity of SBT-A in human hepatocellular carcinoma (HCC) cells and the potential underlying mechanisms. Our results showed that SBT-A inhibited the growth of HCC cells in a dose-dependent manner. SBT-A treatment caused cell cycle arrest and decreased the expression of cyclin B1, cyclin D1, p-Cdc2, and p-Cdc25C. SBT-A triggered cell apoptosis via a caspase-dependent pathway, and cell viability was partially restored by pretreatment with the pan-caspase inhibitor Z-VAD-FMK. In HCC cells, treatment with SBT-A increased the phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), c-Jun N-terminal kinase 1 and 2 (JNK1/2), and p38 mitogen-activated protein kinase (p38 MAPK). Moreover, SBT-A activated endoplasmic reticulum (ER) stress through the upregulation of protein kinase RNA-like ER kinase (PERK), activating transcription factor 4 (ATF-4), and CCAAT-enhancer-binding protein (C/EBP) homologous protein (CHOP). Our data indicate that SBT-A inhibits the proliferation of HCC cells and triggers their apoptosis via the activation of MAPK and ER stress. SBT-A is a potential agent for the treatment of HCC.

Drug-induced cell viability prediction from LINCS-L1000 through WRFEN-XGBoost algorithm

Background

Predicting the drug response of the cancer diseases through the cellular perturbation signatures under the action of specific compounds is very important in personalized medicine. In the process of testing drug responses to the cancer, traditional experimental methods have been greatly hampered by the cost and sample size. At present, the public availability of large amounts of gene expression data makes it a challenging task to use machine learning methods to predict the drug sensitivity.

Results

In this study, we introduced the WRFEN-XGBoost cell viability prediction algorithm based on LINCS-L1000 cell signatures. We integrated the LINCS-L1000, CTRP and Achilles datasets and adopted a weighted fusion algorithm based on random forest and elastic net for key gene selection. Then the FEBPSO algorithm was introduced into XGBoost learning algorithm to predict the cell viability induced by the drugs. The proposed method was compared with some new methods, and it was found that our model achieved good results with 0.83 Pearson correlation. At the same time, we completed the drug sensitivity validation on the NCI60 and CCLE datasets, which further demonstrated the effectiveness of our method.

Conclusions

The results showed that our method was conducive to the elucidation of disease mechanisms and the exploration of new therapies, which greatly promoted the progress of clinical medicine.

Inhibiting P2Y12 in Macrophages Induces Endoplasmic Reticulum Stress and Promotes an Anti-Tumoral Phenotype

The P2Y12 receptor is an adenosine diphosphate responsive G protein-coupled receptor expressed on the surface of platelets and is the pharmacologic target of several anti-thrombotic agents. In this study, we use liver samples from mice with cirrhosis and hepatocellular carcinoma to show that P2Y12 is expressed by macrophages in the liver. Using in vitro methods, we show that inhibition of P2Y12 with ticagrelor enhances tumor cell phagocytosis by macrophages and induces an anti-tumoral phenotype. Treatment with ticagrelor also increases the expression of several actors of the endoplasmic reticulum (ER) stress pathways, suggesting activation of the unfolded protein response (UPR). Inhibiting the UPR with tauroursodeoxycholic acid (Tudca) diminishes the pro-phagocytotic effect of ticagrelor, thereby indicating that P2Y12 mediates macrophage function through activation of ER stress pathways. This could be relevant in the pathogenesis of chronic liver disease and cancer, as macrophages are considered key players in these inflammation-driven pathologies.

Targeting Piezo1 unleashes innate immunity against cancer and infectious disease

Piezo1 is a mechanosensitive ion channel that has gained recognition for its role in regulating diverse physiological processes. However, the influence of Piezo1 in inflammatory disease, including infection and tumor immunity, is not well studied. We postulated that Piezo1 links physical forces to immune regulation in myeloid cells. We found signal transduction via Piezo1 in myeloid cells and established this channel as the primary sensor of mechanical stress in these cells. Global inhibition of Piezo1 with a peptide inhibitor was protective against both cancer and septic shock and resulted in a diminution in suppressive myeloid cells. Moreover, deletion of Piezo1 in myeloid cells protected against cancer and increased survival in polymicrobial sepsis. Mechanistically, we show that mechanical stimulation promotes Piezo1-dependent myeloid cell expansion by suppressing the retinoblastoma gene Rb1 We further show that Piezo1-mediated silencing of Rb1 is regulated via up-regulation of histone deacetylase 2. Collectively, our work uncovers Piezo1 as a targetable immune checkpoint that drives immunosuppressive myelopoiesis in cancer and infectious disease.

The Integrated Stress Response and Phosphorylated Eukaryotic Initiation Factor 2α in Neurodegeneration

The proposed molecular mechanisms underlying neurodegenerative pathogenesis are varied, precluding the development of effective therapies for these increasingly prevalent disorders. One of the most consistent observations across neurodegenerative diseases is the phosphorylation of eukaryotic initiation factor 2α (eIF2α). eIF2α is a translation initiation factor, involved in cap-dependent protein translation, which when phosphorylated causes global translation attenuation. eIF2α phosphorylation is mediated by 4 kinases, which, together with their downstream signaling cascades, constitute the integrated stress response (ISR). While the ISR is activated by stresses commonly observed in neurodegeneration, such as oxidative stress, endoplasmic reticulum stress, and inflammation, it is a canonically adaptive signaling cascade. However, chronic activation of the ISR can contribute to neurodegenerative phenotypes such as neuronal death, memory impairments, and protein aggregation via apoptotic induction and other maladaptive outcomes downstream of phospho-eIF2α-mediated translation inhibition, including neuroinflammation and altered amyloidogenic processing, plausibly in a feed-forward manner. This review examines evidence that dysregulated eIF2a phosphorylation acts as a driver of neurodegeneration, including a survey of observations of ISR signaling in human disease, inspection of the overlap between ISR signaling and neurodegenerative phenomenon, and assessment of recent encouraging findings ameliorating neurodegeneration using developing pharmacological agents which target the ISR. In doing so, gaps in the field, including crosstalk of the ISR kinases and consideration of ISR signaling in nonneuronal central nervous system cell types, are highlighted.

ER stress activates immunosuppressive network: implications for aging and Alzheimer's disease

The endoplasmic reticulum (ER) contains stress sensors which recognize the accumulation of unfolded proteins within the lumen of ER, and subsequently these transducers stimulate the unfolded protein response (UPR). The ER sensors include the IRE1, PERK, and ATF6 transducers which activate the UPR in an attempt to restore the quality of protein folding and thus maintain cellular homeostasis. If there is excessive stress, UPR signaling generates alarmins, e.g., chemokines and cytokines, which activate not only tissue-resident immune cells but also recruit myeloid and lymphoid cells into the affected tissues. ER stress is a crucial inducer of inflammation in many pathological conditions. A chronic low-grade inflammation and cellular senescence have been associated with the aging process and many age-related diseases, such as Alzheimer’s disease. Currently, it is known that immune cells can exhibit great plasticity, i.e., they are able to display both pro-inflammatory and anti-inflammatory phenotypes in a context-dependent manner. The microenvironment encountered in chronic inflammatory conditions triggers a compensatory immunosuppression which defends tissues from excessive inflammation. Recent studies have revealed that chronic ER stress augments the suppressive phenotypes of immune cells, e.g., in tumors and other inflammatory disorders. The activation of immunosuppressive network, including myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg), has been involved in the aging process and Alzheimer’s disease. We will examine in detail whether the ER stress-related changes found in aging tissues and Alzheimer’s disease are associated with the activation of immunosuppressive network, as has been observed in tumors and many chronic inflammatory diseases.

Autophagy and Myeloma

Multiple myeloma is a hematological malignancy. It is characterized by the abnormal clonal proliferation of malignant plasma cells in the bone marrow and the secretion of a large number of monoclonal immunoglobulins or light chains, causing bone destruction, elevated blood calcium levels, anemia, and renal dysfunction. Autophagy has a dual role in the autophagy of myeloma cells. On the one hand, autophagy eliminates abnormal proteins and organelles in cells, prevents gene damage, and inhibits tumorigenesis. On the other hand, once tumors are formed, tumor cells use autophagy to ensure their survival under nutrient-deficient and hypoxic conditions. Excessive autophagy promotes another form of death in tumor cells, autophagic cell death. Targeted autophagy is becoming another new myeloma treatment strategy.

Myeloid-derived suppressor cells in hematological malignancies: friends or foes

Myeloid-derived suppressor cells (MDSCs) are newly identified immature myeloid cells that are characterized by the ability to suppress immune responses and expand during cancer, infection, and inflammatory diseases. Although MDSCs have attracted a lot of attention in the field of tumor immunology in recent years, little is known about their multiple roles in hematological malignancies as opposed to their roles in solid tumors. This review will help researchers better understand the various characteristics and functions of MDSCs, as well as the potential therapeutic applications of MDSCs in hematological malignancies, including lymphoma, multiple myeloma, leukemia, and hematopoietic stem cell transplantation.

GM2-GM3 gangliosides ratio is dependent on GRP94 through down-regulation of GM2-AP cofactor in brain metastasis cells

GRP94 is an ATP-dependent chaperone able to regulate pro-oncogenic signaling pathways. Previous studies have shown a critical role of GRP94 in brain metastasis (BrM) pathogenesis and progression. In this work, an untargeted lipidomic analysis revealed that some lipid species were altered in GRP94-deficient cells, specially GM2 and GM3 gangliosides. The catalytic pathway of GM2 is affected by the low enzymatic activity of β-Hexosaminidase (HexA), responsible for the hydrolysis of GM2 to GM3. Moreover, a deficiency of the GM2-activator protein (GM2-AP), the cofactor of HexA, is observed without alteration of gene expression, indicating a post-transcriptional alteration of GM2-AP in the GRP94-ablated cells. One plausible explanation of these observations is that GM2-AP is a client of GRP94, resulting in defective GM2 catabolic processing and lysosomal accumulation of GM2 in GRP94-ablated cells. Overall, given the role of gangliosides in cell surface dynamics and signaling, their imbalance might be linked to modifications of cell behaviour acquired in BrM progression. This work indicates that GM2-AP could be an important factor in ganglioside balance maintenance. These findings highlight the relevance of GM3 and GM2 gangliosides in BrM and reveal GM2-AP as a promising diagnosis and therapeutic target in BrM research.

Endoplasmic reticulum stress is involved in lipopolysaccharide-induced inflammatory response and apoptosis in goat endometrial stromal cells

Endoplasmic reticulum (ER) stress is involved in regulating cell metabolism, apoptosis, autophagy, and survival. However, there is not enough information about the role of ER stress in lipopolysaccharide (LPS)-induced apoptosis and inflammatory cytokine secretion in the uterus. In this study, we found that LPS induced apoptosis and inflammation in goat endometrial stromal cells (ESCs). LPS treatment inhibited cell viability and cell proliferation. In addition, the genes associated with proliferation, such as proliferating cell nuclear antigen and MKI67, were affected by LPS treatment. Moreover, LPS increased the secretion of interleukin (IL)-1β and IL-8, promoting the levels of MYD88, caspase1, and TRL4. The 4-phenylbutyric acid pretreatment inhibited the expression of unfolded protein response proteins and the secretion of inflammatory cytokines in LPS-treated cells. However, blockage of inositol-requiring enzyme 1 and activating transcription factor 6 did not significantly reduce apoptosis and inflammatory cytokine secretion. Collectively, ER stress involved in LPS-induced apoptosis and inflammatory cytokine increased in goat ESCs. This study provides new insight into the function of ER stress in the pathological process.