Tumor Microenvironment Regulation by the Endoplasmic Reticulum Stress Transmission Mediator Golgi Protein 73 in Mice

Molecular mechanisms of transmitted endoplasmic reticulum stress mediating immune escape of gastric cancer via PVR overexpression in TAMs

Gastric cancer (GC) is the fourth leading cause of cancer death worldwide. Due to the complex tumor microenvironment (TME), the efficacy of immunotherapy in GC has not met expectations. Malignant changes in the TME induce endoplasmic reticulum stress (ERS). ERS can be transmitted between tumor cells and tumor-associated macrophages (TAMs), promoting tumor immune escape, but the specific mechanism in GC remains unclear. We established a TAM model of transmitted ERS (TERS), and iTRAQ proteomic analysis identified overexpressed proteins. The overexpression of poliovirus receptor (PVR) was screened while flow cytometry and ELISA showed that PVR mediated the immunosuppressive function of TAMs by downregulating the proliferative activity and cytotoxicity of cocultured CD8+ T lymphocytes. With EMSA and dual-luciferase reporter assays, we confirmed that erythropoietin-producing hepatocellular receptor A2 (EphA2) affected PVR expression by increasing the transcriptional activity of activator protein-1 (AP-1). MFC cells were mixed with EphA2 knockdown or control RAW264.7 cells to establish subcutaneous tumor models with or without tunicamycin treatment in vivo. The vivo experiments revealed that ERS promoted subcutaneous xenograft growth, which was reversed by EphA2 knockdown. Clinically, GC patients with high expression of PVR and EphA2 tended to have an immunosuppressive TME, which were determined by immunohistochemical and immunofluorescence analyses. In conclusion, the transcriptional activity of AP-1 is upregulated in ERS-transmitted TAMs through EphA2 to increase PVR expression, which promotes immune escape in GC. Our study provides a new perspective on the role of ERS in tumor immunity.

GOLM1 dictates acquired Lenvatinib resistance by a GOLM1-CSN5 positive feedback loop upon EGFR signaling activation in hepatocellular carcinoma

Lenvatinib is a multiple receptor tyrosine kinases inhibitor (TKI) authorized for first-line treatment of hepatocellular carcinoma (HCC). However, Lenvatinib resistance is common in HCC clinical treatment, highlighting the urgent need to understand mechanisms of resistance. Here, we identified Golgi membrane protein 1 (GOLM1), a type II transmembrane protein originally located in the Golgi apparatus, as a novel regulator of Lenvatinib resistance. We found GOLM1 was overexpressed in Lenvatinib resistant human HCC cell lines, blood and HCC samples. Additionally, GOLM1 overexpression contributes to Lenvatinib resistance and HCC progression in vitro and in vivo. Mechanistically, GOLM1 upregulates CSN5 expression through EGFR-STAT3 pathway. Reversely, CSN5 deubiquitinates and stabilizes GOLM1 protein by inhibiting ubiquitin-proteasome pathway of GOLM1. Furthermore, clinical specimens of HCC showed a positive correlation between the activation of the GOLM1-EGFR-STAT3-CSN5 axis. Finally, GOLM1 knockdown was found to act in synergy with Lenvatinib in subcutaneous and orthotopic mouse model. Overall, these findings identify a mechanism of resistance to Lenvatinib treatment for HCC, highlight an effective predictive biomarker of Lenvatinib response in HCC and show that targeting GOLM1 may improve the clinical benefit of Lenvatinib.

Microcystin-LR Regulates Interaction between Tumor Cells and Macrophages via the IRE1α/XBP1 Signaling Pathway to Promote the Progression of Colorectal Cancer

Microcystin-LR (MC-LR), a cyanobacterial toxin, is a potent carcinogen implicated in colorectal cancer (CRC) progression. However, its impact on the tumor microenvironment (TME) during CRC development remains poorly understood. This study investigates the interaction between tumor cells and macrophages mediated by MC-LR within the TME and its influence on CRC progression. CRC mice exposed to MC-LR demonstrated a significant transformation from adenoma to adenocarcinoma. The infiltration of macrophages increased, and the IRE1α/XBP1 pathway was activated in CRC cells after MC-LR exposure, influencing macrophage M2 polarization under co-culture conditions. Additionally, hexokinase 2 (HK2), a downstream target of the IRE1α/XBP1 pathway, was identified, regulating glycolysis and lactate production. The MC-LR-induced IRE1α/XBP1/HK2 axis enhanced lactate production in CRC cells, promoting M2 macrophage polarization. Furthermore, co-culturing MC-LR-exposed CRC cells with macrophages, along with the IRE1α/XBP1 pathway inhibitor 4μ8C and the hexokinase inhibitor 2-DG, suppressed M2 macrophage-induced CRC cell migration, clonogenicity, and M2 macrophage polarization. This study elucidates the mechanism by which MC-LR-mediated interactions through the IRE1α/XBP1 pathway promote CRC progression, highlighting potential therapeutic targets.

Golgi Protein 73 Promotes Angiogenesis in Hepatocellular Carcinoma

Golgi protein 73 (GP73), a resident protein of the Golgi apparatus, is notably elevated in hepatocellular carcinoma (HCC). While its critical role in remodeling the tumor microenvironment (TME) is recognized, the intricate mechanisms are not fully understood. This study reveals that GP73 in HCC cells interacts with prolyl hydroxylase-2 (PHD-2) in a competitive manner, thereby impeding the hydroxylation of hypoxia-induced factor-1α (HIF-1α). The effect above promotes the production and secretion of vascular endothelial growth factor A (VEGFA). Moreover, exosomal GP73 derived from HCC cells can be internalized by human umbilical vein endothelial cells (HUVECs) and competitively interact with HECTD1, an E3 ubiquitin ligase targeting growth factor receptor-bound protein 2 (GRB2). This interaction stabilizes GRB2, thereby activating the Ras-mitogen-activated protein kinase (MAPK) signaling pathway. Consequently, escalated levels of GP73 intensify VEGF production in HCC cells and potentiate mitogenic signaling in vascular endothelial cells, fostering angiogenesis in the TME. Our findings propose that GP73 might serve as a novel target for anti-angiogenic therapy in HCC.

Integrating Single-Cell and Spatial Transcriptomics to Uncover and Elucidate GP73-Mediated Pro-Angiogenic Regulatory Networks in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) was characterized as being hypervascular. In the present study, we generated a single-cell spatial transcriptomic landscape of the vasculogenic etiology of HCC and illustrated overexpressed Golgi phosphoprotein 73 (GP73) HCC cells exerting cellular communication with vascular endothelial cells with high pro-angiogenesis potential via multiple receptor-ligand interactions in the process of tumor vascular development. Specifically, we uncovered an interactive GP73-mediated regulatory network coordinated with c-Myc, lactate, Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway, and endoplasmic reticulum stress (ERS) signals in HCC cells and elucidated its pro-angiogenic roles in vitro and in vivo. Mechanistically, we found that GP73, the pivotal hub gene, was activated by histone lactylation and c-Myc, which stimulated the phosphorylation of downstream STAT3 by directly binding STAT3 and simultaneously enhancing glucose-regulated protein 78 (GRP78)-induced ERS. STAT3 potentiates GP73-mediated pro-angiogenic functions. Clinically, serum GP73 levels were positively correlated with HCC response to anti-angiogenic regimens and were essential for a prognostic nomogram showing good predictive performance for determining 6-month and 1-year survival in patients with HCC treated with anti-angiogenic therapy. Taken together, the aforementioned data characterized the pro-angiogenic roles and mechanisms of a GP73-mediated network and proved that GP73 is a crucial tumor angiogenesis niche gene with favorable anti-angiogenic potential in the treatment of HCC.

Deficiency of ASGR1 promotes liver injury by increasing GP73-mediated hepatic endoplasmic reticulum stress

Liver injury is a core pathological process in the majority of liver diseases, yet the genetic factors predisposing individuals to its initiation and progression remain poorly understood. Here we show that asialoglycoprotein receptor 1 (ASGR1), a lectin specifically expressed in the liver, is downregulated in patients with liver fibrosis or cirrhosis and male mice with liver injury. ASGR1 deficiency exacerbates while its overexpression mitigates acetaminophen-induced acute and CCl4-induced chronic liver injuries in male mice. Mechanistically, ASGR1 binds to an endoplasmic reticulum stress mediator GP73 and facilitates its lysosomal degradation. ASGR1 depletion increases circulating GP73 levels and promotes the interaction between GP73 and BIP to activate endoplasmic reticulum stress, leading to liver injury. Neutralization of GP73 not only attenuates ASGR1 deficiency-induced liver injuries but also improves survival in mice received a lethal dose of acetaminophen. Collectively, these findings identify ASGR1 as a potential genetic determinant of susceptibility to liver injury and propose it as a therapeutic target for the treatment of liver injury.

Inhibiting the endoplasmic reticulum stress response enhances the effect of doxorubicin by altering the lipid metabolism of liver cancer cells

Hepatocellular carcinoma (HCC) is characterized by a low and variable response to chemotherapeutic treatments. One contributing factor to the overall pharmacodynamics is the activation of endoplasmic reticulum (ER) stress pathways. This is a cellular stress mechanism that becomes activated when the cell's need for protein synthesis surpasses the ER's capacity to maintain accurate protein folding, and has been implicated in creating drug-resistance in several solid tumors.

OBJECTIVE

To identify the role of ER-stress and lipid metabolism in mediating drug response in HCC.

METHODS

By using a chemically-induced mouse model for HCC, we administered the ER-stress inhibitor 4μ8C and/or doxorubicin (DOX) twice weekly for three weeks post-tumor initiation. Histological analyses were performed alongside comprehensive molecular biology and lipidomics assessments of isolated liver samples. In vitro models, including HCC cells, spheroids, and patient-derived liver organoids were subjected to 4μ8C and/or DOX, enabling us to assess their synergistic effects on cellular viability, lipid metabolism, and oxygen consumption rate.

RESULTS

We reveal a pivotal synergy between ER-stress modulation and drug response in HCC. The inhibition of ER-stress using 4μ8C not only enhances the cytotoxic effect of DOX, but also significantly reduces cellular lipid metabolism. This intricate interplay culminates in the deprivation of energy reserves essential for the sustenance of tumor cells.

CONCLUSIONS

This study elucidates the interplay between lipid metabolism and ER-stress modulation in enhancing doxorubicin efficacy in HCC. This novel approach not only deepens our understanding of the disease, but also uncovers a promising avenue for therapeutic innovation. The long-term impact of our study could open the possibility of ER-stress inhibitors and/or lipase inhibitors as adjuvant treatments for HCC-patients.

A pan-cancer analysis of the oncogenic role of Golgi transport 1B in human tumors

Background

Owing to the aggressiveness and treatment-refractory nature of cancer, ideal candidates for early diagnosis and treatment are needed. Golgi transport 1B (GOLT1B) has been associated with cellular malignant behaviors and immune responses in colorectal and lung cancer, but a systematic pan-cancer analysis on GOLT1B has not been conducted.

Methods

The expression status and clinical association of GOLT1B in The Cancer Genome Atlas (TCGA) were analyzed. Genetic and methylation alterations in GOLT1B were explored. The relationship between GOLT1B and immune cell infiltration was also investigated. Genes related to GOLT1B expression were selected and analyzed.

Results

GOLT1B was highly expressed in most tumors, and there was a positive correlation between GOLT1B expression and clinical pathological parameters. High expression levels of GOLT1B have been associated with poor prognosis of most cancers. Copy number amplification was the primary type of GOLT1B genetic alterations, which was related to the prognosis of pan-cancer cases. There were different levels of GOLT1B promoter methylation across cancer types. The methylation level of the probe cg07371838 and cg25816357 was closely associated with prognosis in diverse cancers. There was also a positive correlation between GOLT1B genetic alterations and CD4+ T lymphocytes, especially the Th2 subset, as well as between GOLT1B expression and the estimated infiltration value of cancer-associated fibroblasts. Serine/threonine kinase receptor-associated protein (STRAP), integrator complex subunit 13 (INTS13), and ethanolamine kinase 1 (ETNK1) were the most relevant genes for GOLT1B expression, and their interactions with GOLT1B were involved in regulating the transforming growth factor (TGF)-β receptor signaling pathway and epithelial-mesenchymal transition (EMT).

Conclusions

This pan-cancer analysis provided a comprehensive understanding of the oncogenic role of GOLT1B, highlighting a potential mechanism whereby GOLT1B influences the tumor microenvironment, as well as cancer immunotherapy.

The role of tumor-associated macrophages in hepatocellular carcinoma progression: A narrative review

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world, with complex etiology and mechanism, and a high mortality rate. Tumor-associated macrophages (TAMs) are an important part of the HCC tumor microenvironment. Studies in recent years have shown that TAMs are involved in multiple stages of HCC and are related to treatment and prognosis in HCC. The specific mechanisms between TAMs and HCC are gradually being revealed. This paper reviews recent advances in the mechanisms associated with TAMs in HCC, concentrating on an overview of effects of TAMs on drug resistance in HCC and the signaling pathways linked with HCC, providing clues for the treatment and prognosis determination of HCC.

GRP78-CAR T cell effector function against solid and brain tumors is controlled by GRP78 expression on T cells

Lack of targetable antigens is a key limitation for developing successful T cell-based immunotherapies. Members of the unfolded protein response (UPR) represent ideal immunotherapy targets because the UPR regulates the ability of cancer cells to resist cell death, sustain proliferation, and metastasize. Glucose-regulated protein 78 (GRP78) is a key UPR regulator that is overexpressed and translocated to the cell surface of a wide variety of cancers in response to elevated endoplasmic reticulum (ER) stress. We show that GRP78 is highly expressed on the cell surface of multiple solid and brain tumors, making cell surface GRP78 a promising chimeric antigen receptor (CAR) T cell target. We demonstrate that GRP78-CAR T cells can recognize and kill GRP78+ brain and solid tumors in vitro and in vivo. Additionally, our findings demonstrate that GRP78 is upregulated on CAR T cells upon T cell activation; however, this expression is tumor-cell-line specific and results in heterogeneous GRP78-CAR T cell therapeutic response.

Cancer Stem Cells and the Tumor Microenvironment in Tumor Drug Resistance

Although there has been some progress in the efficacy of anti-cancer drugs, drug resistance remains challenging. Cancer stem cells (CSCs) are self-renewing and differentiate into cancer tissues with tumor heterogeneity. CSCs are associated with the progression of breast, colon, and lung cancers. Hence, recent studies have focused on the role of CSCs in resistance to anti-cancer drugs. Increasing evidence suggests that CSCs interact with components of the tumor microenvironment (TME), such as vascular and immune cells, as well as various cytokines, and are regulated by multiple signaling pathways, thereby promoting drug resistance in various cancers. Therefore, it is important to clarify the mechanisms underlying the crosstalk between CSCs and the TME for the development of targeted anti-cancer therapies.

Inhibition of MiR-106b-5p mediated by exosomes mitigates acute kidney injury by modulating transmissible endoplasmic reticulum stress and M1 macrophage polarization

Acute kidney injury (AKI), mainly caused by Ischemia/reperfusion injury (IRI), is a common and severe life-threatening disease with high mortality. Accumulating evidence suggested a direct relationship between endoplasmic reticulum (ER) stress response and AKI progression. However, the role of the transmissible ER stress response, a new modulator of cell-to-cell communication, in influencing intercellular communication between renal tubular epithelial cells (TECs) and macrophages in the AKI microenvironment remains to be determined. To address this issue, we first demonstrate that TECs undergoing ER stress are able to transmit ER stress to macrophages via exosomes, promoting macrophage polarization towards the pro-inflammatory M1 phenotype in vitro and in vivo. Besides, the miR-106b-5p/ATL3 signalling axis plays a pivotal role in the transmission of ER stress in the intercellular crosstalk between TECs and macrophages. We observed an apparent increase in the expression of miR-106b-5p in ER-stressed TECs. Furthermore, we confirmed that ALT3 is a potential target protein of miR-106b-5p. Notably, the inhibition of miR-106b-5p expression in macrophages not only restores ATL3 protein level but also decreases transmissible ER stress and hinders M1 polarization, thus alleviating AKI progression. Additionally, our results suggest that the level of exosomal miR-106b-5p in urine is closely correlated with the severity of AKI patients. Taken together, our study sheds new light on the crucial role of transmissible ER stress in the treatment of AKI through the regulation of the miR-106b-5p/ATL3 axis, offering new ideas for treating AKI.

Endoplasmic Reticulum Stress in the Brain Tumor Immune Microenvironment

Immunotherapy has emerged as a powerful strategy for halting cancer progression. However, primary malignancies affecting the brain have been exempt to this success. Indeed, brain tumors continue to portend severe morbidity and remain a globally lethal disease. Extensive efforts have been directed at understanding how tumor cells survive and propagate within the unique microenvironment of the central nervous system (CNS). Cancer genetic aberrations and metabolic abnormalities provoke a state of persistent endoplasmic reticulum (ER) stress that in turn promotes tumor growth, invasion, therapeutic resistance, and the dynamic reprogramming of the infiltrating immune cells. Consequently, targeting ER stress is a potential therapeutic approach. In this work, we provide an overview of how ER stress response is advantageous to brain tumor development, discuss the significance of ER stress in governing antitumor immunity, and put forth therapeutic strategies of regulating ER stress to augment the effect of immunotherapy for primary CNS tumors.

Hepatitis B virus X protein promotes MAN1B1 expression by enhancing stability of GRP78 via TRIM25 to facilitate hepatocarcinogenesis

BACKGROUND

GRP78 has been implicated in hepatocarcinogenesis. However, the clinical relevance, biological functions and related regulatory mechanisms of GRP78 in hepatitis B virus (HBV)-associated hepatoma carcinoma (HCC) remain elusive.

METHODS

The association between GRP78 expression and HBV-related HCC was investigated. The effects of HBV X protein (HBX) on GRP78 and MAN1B1 expression, biological functions of GRP78 and MAN1B1 in HBX-mediated HCC cells and mechanisms related to TRIM25 on GRP78 upregulation to induce MAN1B1 expression in HBX-related HCC cells were examined.

RESULTS

GRP78 expression was correlated with poor prognosis in HBV-positive HCC. HBX increased MAN1B1 protein expression depending on GRP78, and HBX enhanced the levels of MAN1B1 to promote proliferation, migration and PI3-K/mTOR signalling pathway activation in HCC cells. GRP78 activates Smad4 via its interaction with Smad4 to increase MAN1B1 expression in HBX-expressing HCC cells. TRIM25 enhanced the stability of GRP78 by inhibiting its ubiquitination. HBX binds to GRP78 and TRIM25 and accelerates their interaction of GRP78 and TRIM25, leading to an increase in GRP78 expression.

CONCLUSIONS

HBX enhances the stability of GRP78 through TRIM25 to increase the expression of MAN1B1 to facilitate tumorigenesis, and we provide new insights into the molecular mechanisms underlying HBV-induced malignancy.

GP73 blockade alleviates abnormal glucose homeostasis in diabetic mice

Golgi protein 73 (GP73), also called Golgi membrane protein 1 (GOLM1), is a resident Golgi type II transmembrane protein and is considered as a serum marker for the detection of a variety of cancers. A recent work revealed the role of the secreted GP73 in stimulating liver glucose production and systemic glucose homeostasis. Since exaggerated hepatic glucose production plays a key role in the pathogenesis of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), GP73 may thus represent a potential therapeutic target for treating diabetic patients with pathologically elevated levels. Here, in this study, we found that the circulating GP73 levels were significantly elevated in T2DM and positively correlated with hemoglobin A1c. Notably, the aberrantly upregulated GP73 levels were indispensable for the enhanced protein kinase A signaling pathway associated with diabetes. In diet-induced obese mouse model, GP73 siRNA primarily targeting liver tissue was potently effective in alleviating abnormal glucose metabolism. Ablation of GP73 from whole animals also exerted a profound glucose-lowering effect. Importantly, neutralizing circulating GP73 improved glucose metabolism in streptozotocin (STZ) and high-fat diet/STZ-induced diabetic mice. We thus concluded that GP73 was a feasible therapeutic target for the treatment of diabetes.

Exosomal NAMPT from chronic lymphocytic leukemia cells orchestrate monocyte survival and phenotype under endoplasmic reticulum stress

Endoplasmic reticulum (ER) stress has been reported to be transmitted from tumor cells to immune cells via exosome and implicated in immune escape. However, the influence of ER stress on monocytes in chronic lymphocytic leukemia (CLL) cells is largely unknown. Here, we observed the expression of ER stress markers (GRP78, ATF6, PERK, IRE1a, and XBP1s) in CLL cells. The increasing mRNA expression of these ER stress response components was positively correlated with more aggressive disease. Exosome from ER stress inducer tunicamycin (TM)-primed CLL cells (ERS-exo) up-regulated the expression of ER stress marker on monocytes, indicating ER stress is transmissible in vitro via exosome. Treatment with ERS-exo promoted the survival of monocytes and induced phenotypic changes with a significantly larger percentage of CD14⁺ CD16⁺ monocytes. Finally, we identified exosome-mediated transfer of extracellular nicotinamide phosphoribosyltransferase (eNAMPT) from ER stressed CLL cells into monocytes as a novel mechanism through which ERS-exo regulated monocytes. Exosomal eNAMPT up-regulated nicotinamide adenine dinucleotide (NAD⁺ ) production which subsequently activated SIRT1-C/EBPβ signaling pathway in monocytes. Our results suggest the role of ER stress in mediating immunological dysfunction in CLL.

SHH/GLI2-TGF-β1 feedback loop between cancer cells and tumor-associated macrophages maintains epithelial-mesenchymal transition and endoplasmic reticulum homeostasis in cholangiocarcinoma

BACKGROUND

Tumor-associated macrophages (TAMs) play a dual role in tumors. However, the factors which drive the function of TAMs in cholangiocarcinoma remain largely undefined.

METHODS

SHH signaling pathway and endoplasmic reticulum stress (ERS) indicators were detected in clinical tissues and cholangiocarcinoma cell lines. TAMs were co-cultured with cholangiocarcinoma cells under conditions of hypoxia/normoxia. Polarized TAMs were counted by flow cytometry, and TGF-β1 levels in cell supernatants were detected by ELISA. The effects of glioma-associated oncogene GLI2 on TAMs themselves and cholangiocarcinoma cells were examined by conducting interference and overexpression assays.

RESULTS

The SHH signaling pathway and ERS were both activated in tumor tissues or tumor cell lines under conditions of hypoxia. In co-culture experiments, the presence of cholangiocarcinoma cells increased the proportion of M2-polarized TAMs and the secretion of TGF-β1 by TAMs, while knockdown of SHH expression reversed those increases. Overexpression of GLI2 in TAMS or stimulation of TAMS with Hh-Ag1.5 increased their levels of TGF-β1 expression. Furthermore, under co-culture conditions, interference with GLI2 expression in TAMs reduced the tumor cell migration, invasion, and ER homeostasis induced by Hh-Ag1.5-pretreated TAMs. Under conditions of hypoxia, the presence of cholangiocarcinoma cells promoted the expression of GLI2 and TGF-β1 in Tams, and in turn, TAMs inhibited the apoptosis and promoted the migration and invasion of cholangiocarcinoma cells. In vivo, an injection of cholangiocarcinoma cells plus TAMs contributed to the growth, EMT, and ER homeostasis of tumor tissue, while an injection of TAMs with GLI2 knockdown had the opposite effects.

CONCLUSION

Cholangiocarcinoma cells regulated TAM polarization and TGF-β1 secretion via a paracrine SHH signaling pathway, and in turn, TAMs promoted the growth, EMT, and ER homeostasis of cholangiocarcinoma cells via TGF-β1.

The Tumor Microenvironment of Hepatocellular Carcinoma: Untying an Intricate Immunological Network

HCC, the most prevalent form of primary liver cancer, is prototypically an inflammation-driven cancer developing after years of inflammatory insults. Consequently, the hepatic microenvironment is a site of complex immunological activities. Moreover, the tolerogenic nature of the liver can act as a barrier to anti-tumor immunity, fostering cancer progression and resistance to immunotherapies based on immune checkpoint inhibitors (ICB). In addition to being a site of primary carcinogenesis, many cancer types have high tropism for the liver, and patients diagnosed with liver metastasis have a dismal prognosis. Therefore, understanding the immunological networks characterizing the tumor microenvironment (TME) of HCC will deepen our understanding of liver immunity, and it will underpin the dominant mechanisms controlling both spontaneous and therapy-induced anti-tumor immune responses. Herein, we discuss the contributions of the cellular and molecular components of the liver immune contexture during HCC onset and progression by underscoring how the balance between antagonistic immune responses can recast the properties of the TME and the response to ICB.

Possible roles of Golgi protein-73 in liver diseases

Golgi protein 73 (also known as GP73 or GOLPH2) is a transmembrane glycoprotein present in the Golgi apparatus. In diseased states, GP73 is expressed by hepatocytes rather than by bile duct epithelial cells. Many studies have reported that serum GP73 (sGP73) is a marker for hepatocellular carcinoma (HCC). For HCC diagnosis, the sensitivities of sGP73 were higher than that of other markers but the specificities were lower. Considering that the concentration of GP73 is consistent with the stage of liver fibrosis and cirrhosis, some studies have implied that GP73 may be a marker for liver fibrosis and cirrhosis. Increased sGP73 levels may result from hepatic inflammatory activity. During liver inflammation, GP73 facilitates liver tissue regeneration. By summarizing the studies on GP73 in liver diseases, we wish to focus on the mechanism of GP73 in diseases.

GOLM1 depletion modifies cellular sphingolipid metabolism and adversely affects cell growth

Golgi membrane protein 1 (GOLM1) is a Golgi-resident type 2 transmembrane protein known to be overexpressed in several cancers, including hepatocellular carcinoma (HCC), as well as in viral infections. However, the role of GOLM1 in lipid metabolism remains enigmatic. In this study, we employed siRNA-mediated GOLM1 depletion in Huh-7 HCC cells to study the role of GOLM1 in lipid metabolism. Mass spectrometric lipidomic analysis in GOLM1 knockdown cells showed an aberrant accumulation of sphingolipids, such as ceramides, hexosylceramides, dihexosylceramides, sphinganine, sphingosine, and ceramide phosphate, along with cholesteryl esters. Furthermore, we observed a reduction in phosphatidylethanolamines and lysophosphatidylethanolamines. In addition, Seahorse extracellular flux analysis indicated a reduction in mitochondrial oxygen consumption rate upon GOLM1 depletion. Finally, alterations in Golgi structure and distribution were observed both by electron microscopy imaging and immunofluorescence microscopy analysis. Importantly, we found that GOLM1 depletion also affected cell proliferation and cell cycle progression in Huh-7 HCC cells. The Golgi structural defects induced by GOLM1 reduction might potentially affect the trafficking of proteins and lipids leading to distorted intracellular lipid homeostasis, which may result in organelle dysfunction and altered cell growth. In conclusion, we demonstrate that GOLM1 depletion affects sphingolipid metabolism, mitochondrial function, Golgi structure, and proliferation of HCC cells.

Ubiquitin ligase RNF125 targets PD-L1 for ubiquitination and degradation

As a critical immune checkpoint molecule, PD-L1 is expressed at significantly higher levels in multiple neoplastic tissues compared to normal ones. PD-L1/PD-1 axis is a critical target for tumor immunotherapy, blocking the PD-L1/PD-1 axis is recognized and has achieved unprecedented success in clinical applications. However, the clinical efficacy of therapies targeting the PD-1/PD-L1 pathway remains limited, emphasizing the need for the mechanistic elucidation of PD-1/PD-L1 expression. In this study, we found that RNF125 interacted with PD-L1 and regulated PD-L1 protein expression. Mechanistically, RNF125 promoted K48-linked polyubiquitination of PD-L1 and mediated its degradation. Notably, MC-38 and H22 cell lines with RNF125 knockout, transplanted in C57BL/6 mice, exhibited a higher PD-L1 level and faster tumor growth than their parental cell lines. In contrast, overexpression of RNF125 in MC-38 and H22 cells had the opposite effect, resulting in lower PD-L1 levels and delayed tumor growth compared with parental cell lines. In addition, immunohistochemical analysis of MC-38 tumors with RNF125 overexpression showed significantly increased infiltration of CD4+, CD8+ T cells and macrophages. Consistent with these findings, analyses using The Cancer Genome Atlas (TCGA) public database revealed a positive correlation of RNF125 expression with CD4+, CD8+ T cell and macrophage tumor infiltration. Moreover, RNF125 expression was significantly downregulated in several human cancer tissues, and was negatively correlated with the clinical stage of these tumors, and patients with higher RNF125 expression had better clinical outcomes. Our findings identify a novel mechanism for regulating PD-L1 expression and may provide a new strategy to increase the efficacy of immunotherapy.

Transmissible ER stress between macrophages and tumor cells configures tumor microenvironment

Endoplasmic reticulum (ER) stress initiates the unfolded protein response (UPR) and is decisive for tumor cell growth and tumor microenvironment (TME) maintenance. Tumor cells persistently undergo ER stress and could transmit it to the neighboring macrophages and surroundings. Tumor infiltrating macrophages can also adapt to the microenvironment variations to fulfill their highly energy-demanding and biological functions via ER stress. However, whether the different macrophage populations differentially sense ER stress and transmit ER stress to surrounding tumor cells has not yet been elucidated. Here, we aimed to investigate the role of transmissible ER stress, a novel regulator of intercellular communication in the TME. Murine bone marrow-derived macrophage (BMDM) can be polarized toward distinct functional endpoints termed classical (M1) and alternative (M2) activation, and their polarization status has been shown to be tightly correlated with their functional significance. We showed that tumor cells could receive the transmissible ER stress from two differentially polarized macrophage populations with different extent of ER stress activation. The proinflammatory M1-like macrophages respond to ER stress with less extent, however they could transmit more ER stress to tumor cells. Moreover, by analyzing the secreted components of two ER-stressed macrophage populations, we identified certain damage-associated molecular patterns (DAMPs), including S100A8 and S100A9, which are dominantly secreted by M1-like macrophages could lead to significant recipient tumor cells death in synergy with transferred ER stress.

The Single-Cell Level Perspective of the Tumor Microenvironment and Its Remodeling by CAR-T Cells

The tumor microenvironment (TME) is a complex milieu consisting of lymphoid cells, myeloid cells, fibroblasts, and multiple molecules, which play a key role in tumor progression and immunotherapy. TME is characterized by immune-suppressive features, which release anti-inflammatory cytokines such as IL-4 and TGFβ to skew the T cells to a Th2 state as well to polarize tumor-associated macrophages (TAMs) to an anti-inflammatory phenotype to curb the immunotherapy. Considering the heterogeneity of the TME and its role in determining response to chimeric antigen receptor (CAR)-T cells, delineating TME at a single-cell level will provide useful information for cancer treatment. First, we discuss cellular and molecular features that curb the response to CAR-T cells, for example, high expression of immune checkpoint molecules (PD-1, LAG3) and anti-inflammatory cytokines (IL-4, TGFb) that block CAR-T cell function. Then, we summarize how newly invented single-cell technologies such as spatial multi-omics would benefit the understanding of cancer immunotherapy. Finally, we will further describe recent attempts of CAR-T to remodel TME by arming the CAR-T with anti-PD-1 single-chain variants or Th1 triggering cytokines (such as IL-7, IL-12) to remodel TME into a pro-inflammatory state. Herein, we review the single-cell-level signatures of TME and the strategies of CAR-T to remodel TME.

Endoplasmic Reticulum Stress of Oral Squamous Cell Carcinoma Induces Immunosuppression of Neutrophils

The endoplasmic reticulum (ER) stress of cancer cells not only determined cancer cell fate but also indirectly triggered proinflammatory or immunosuppressive responses of macrophages. In addition, ER stressed neutrophils were known to acquire immunosuppressive activity with surface expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). Since the importance of tumor ER stress and immunosuppressive neutrophils has been emphasized in head and neck cancers, we hypothesized that the ER stress of oral squamous cell carcinoma (OSCC) could transform neutrophils into LOX-1 expressing immunosuppressive phenotype. Two human OSCC cell lines, SCC25 and OML1, were treated with either vehicle or thapsigargin (THG), an ER stress inducer. These tumor conditioned media (TCM) were collected accordingly. Then human peripheral blood neutrophils from healthy donors were cultured in these TCM. The results showed that neutrophils cultured in THG-treated TCM had higher expression of LOX-1 compared with those cultured in vehicle-treated TCM. Moreover, by interleukin-2/anti-CD3/anti-CD28 activated autologous T cell proliferation assay, neutrophils conditioned by THG-treated TCM were shown to inhibit T cell proliferation more significantly than those conditioned by vehicle-treated TCM. These novel findings indicated that the ER stress of OSCC could be transmitted to neutrophils which in turn expressed LOX-1 and obtained immunosuppressive ability. Our findings further supported the existence of "transmissible" ER stress between tumor cells and neutrophils.

Role of Exosomes in Immune Microenvironment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Since most patients with HCC are diagnosed at the intermediate or advanced stage and because HCC has a high incidence of metastasis and recurrence, it is one of the leading causes of cancer death. Exosomes are a subtype of extracellular vesicles and are typically 30-150 nm in diameter. Originating from endosomes, they can be secreted by almost all living cells. They are widely present in various body fluids and serve as an important medium for the interactions between cells. A series of studies have revealed that exosomes-mediated intercellular transfer of proteins, nucleic acids, and metabolites plays a crucial role in the initiation and progression of HCC, hypoxia and angiogenesis, chemotherapy sensitivity, and cell death mode and regulates the immune microenvironment. In this paper, we reviewed the recent researches on the multiple roles of tumor-associated exosomes in the progression of HCC. We laid particular focus on those researches that reveal how exosomes regulate the tumor immune microenvironment (TIME) and how exosomal cargos affect the progression of HCC. Besides, we emphasize some prospective directions to achieve a more accurate and complete analysis of the HCC immune microenvironment.

GP73 is a glucogenic hormone contributing to SARS-CoV-2-induced hyperglycemia

Severe cases of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are associated with elevated blood glucose levels and metabolic complications. However, the molecular mechanisms for how SARS-CoV-2 infection alters glycometabolic control are incompletely understood. Here, we connect the circulating protein GP73 with enhanced hepatic gluconeogenesis during SARS-CoV-2 infection. We first demonstrate that GP73 secretion is induced in multiple tissues upon fasting and that GP73 stimulates hepatic gluconeogenesis through the cAMP/PKA signaling pathway. We further show that GP73 secretion is increased in cultured cells infected with SARS-CoV-2, after overexpression of SARS-CoV-2 nucleocapsid and spike proteins and in lungs and livers of mice infected with a mouse-adapted SARS-CoV-2 strain. GP73 blockade with an antibody inhibits excessive glucogenesis stimulated by SARS-CoV-2 in vitro and lowers elevated fasting blood glucose levels in infected mice. In patients with COVID-19, plasma GP73 levels are elevated and positively correlate with blood glucose levels. Our data suggest that GP73 is a glucogenic hormone that likely contributes to SARS-CoV-2-induced abnormalities in systemic glucose metabolism.

Macrophages as key regulators of liver health and disease

Macrophages are a heterogeneous population of innate immune cells and key cellular components of the liver. Hepatic macrophages consist of embryologically-derived resident Kupffer cells (KC), recruited monocyte-derived macrophages (MDM) and capsular macrophages. Both the diversity and plasticity of hepatic macrophage subsets explain their different functions in the maintenance of hepatic homeostasis and in injury processes in acute and chronic liver diseases. In this review, we assess the evidence for macrophage involvement in regulating both liver health and injury responses in liver diseases including acute liver injury (ALI), chronic liver disease (CLD) (including liver fibrosis) and hepatocellular carcinoma (HCC). In healthy livers, KC display critical functions such as phagocytosis, danger signal recognition, cytokine release, antigen processing and the ability to orchestrate immune responses and maintain immunological tolerance. However, in most liver diseases there is a striking hepatic MDM expansion, which orchestrate both disease progression and regression. Single-cell approaches have transformed our understanding of liver macrophage heterogeneity, dynamics, and functions in both human samples and preclinical models. We will further discuss the new insights provided by these approaches and how they are enabling high-fidelity work to specifically identify pathogenic macrophage subpopulations. Given the important role of macrophages in regulating injury responses in a broad range of settings, there is now a huge interest in developing new therapeutic strategies aimed at targeting macrophages. Therefore, we also review the current approaches being used to modulate macrophage function in liver diseases and discuss the therapeutic potential of targeting macrophage subpopulations as a novel treatment strategy for patients with liver disorders.

Golgi Phosphoprotein 73: The Driver of Epithelial-Mesenchymal Transition in Cancer

Golgi phosphoprotein 73 (GP73, also termed as GOLM1 or GOLPH2) is a glycosylated protein residing on cis-Golgi cisternae and highly expressed in various types of cancer tissues. Since GP73 is a secretory protein and detectable in serum derived from cancer patients, it has been regarded as a novel serum biomarker for the diagnosis of different cancers, especially hepatocellular carcinoma (HCC). However, the functional roles of GP73 in cancer development are still poorly understood. In recent years, it has been discovered that GP73 acts as a multifunctional protein-facilitating cancer progression, and strikingly, it has been identified as a leading factor promoting epithelial-mesenchymal transition (EMT) of cancer cells and causing cancer metastasis. In this review, we have overviewed the latest findings of the functional roles of GP73 in elevating cancer progression, especially in facilitating EMT and cancer metastasis through modulating expression, transactivation, and trafficking of EMT-related proteins. In addition, unsolved research fields of GP73 have been lightened, which might be helpful to elucidate the regulatory mechanisms of GP73 on EMT and provide potential approaches in therapeutics against cancer metastasis.

Involvement of endoplasmic reticulum stress-activated PERK-eIF2α-ATF4 signaling pathway in T-2 toxin-induced apoptosis of porcine renal epithelial cells

T-2 toxin is a highly toxic trichothecene that can induce toxic effects in a variety of organs and tissues, but the pathogenesis of its nephrotoxicity has not been elucidated. In this study, we assessed the involvement of protein kinase RNA-like ER kinase (PERK)-mediated endoplasmic reticulum (ER) stress and apoptosis in PK-15 cells cultured at different concentrations of T-2 toxin. Cell viability, antioxidant capacity, intracellular calcium (Ca²⁺) content, apoptotic rate, levels of ER stress, and apoptosis-related proteins were studied. T-2 toxin inhibited cell proliferation; increased the apoptosis rate; and was accompanied by increased cleaved caspase-3 expression, altered intracellular oxidative stress marker levels, and intracellular Ca²⁺ overloading. The ER stress inhibitor 4-phenylbutyrate (4-PBA) and PERK selective inhibitor GSK2606414 prevented the decrease of cell activity and apoptosis caused by T-2 toxin. The altered expression of glucose regulatory protein 78 (GRP78), C/EBP homologous protein (CHOP), and caspase-12 proved that ER stress was involved in cell injury triggered by T-2 toxin. T-2 toxin activated the phosphorylation of PERK and the alpha subunit of eukaryotic initiation factor 2 (eIF2α) and upregulated the activating transcription factor 4 (ATF4), thereby triggering ER stress via the GRP78/PERK/CHOP signaling pathway. This study provides a new perspective for understanding the nephrotoxicity of T-2 toxin.

GP73 is a TBC-domain Rab GTPase-activating protein contributing to the pathogenesis of non-alcoholic fatty liver disease without obesity

The prevalence of non-obese nonalcoholic fatty liver disease (NAFLD) is increasing worldwide with unclear etiology and pathogenesis. Here, we show GP73, a Golgi protein upregulated in livers from patients with a variety of liver diseases, exhibits Rab GTPase-activating protein (GAP) activity regulating ApoB export. Upon regular-diet feeding, liver-GP73-high mice display non-obese NAFLD phenotype, characterized by reduced body weight, intrahepatic lipid accumulation, and gradual insulin resistance development, none of which can be recapitulated in liver-GAP inactive GP73-high mice. Common and specific gene expression signatures associated with GP73-induced non-obese NAFLD and high-fat diet (HFD)-induced obese NAFLD are revealed. Notably, metformin inactivates the GAP activity of GP73 and alleviates GP73-induced non-obese NAFLD. GP73 is pathologically elevated in NAFLD individuals without obesity, and GP73 blockade improves whole-body metabolism in non-obese NAFLD mouse model. These findings reveal a pathophysiological role of GP73 in triggering non-obese NAFLD and may offer an opportunity for clinical intervention.

Dysregulation of lipid metabolism and transport contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Here the authors identify GP73 as a TBC-domain Rab GTPase-activating protein that regulates very low-density lipoprotein export and promotes NAFLD development in mice.

CCL23 in Balancing the Act of Endoplasmic Reticulum Stress and Antitumor Immunity in Hepatocellular Carcinoma

Endoplasmic reticulum (ER) stress is a cellular process in response to stress stimuli in protecting functional activities. However, sustained hyperactive ER stress influences tumor growth and development. Hepatocytes are enriched with ER and highly susceptible to ER perturbations and stress, which contribute to immunosuppression and the development of aggressive and drug-resistant hepatocellular carcinoma (HCC). ER stress-induced inflammation and tumor-derived chemokines influence the immune cell composition at the tumor site. Consequently, a decrease in the CCL23 chemokine in hepatic tumors is associated with poor survival of HCC patients and could be a mechanism hepatic tumor cells use to evade the immune system. This article describes the prospective role of CCL23 in alleviating ER stress and its impact on the HCC tumor microenvironment in promoting antitumor immunity. Moreover, approaches to reactivate CCL23 combined with immune checkpoint blockade or chemotherapy drugs may provide novel opportunities to target hepatocellular carcinoma.

The immunological and metabolic landscape in primary and metastatic liver cancer

The liver is the sixth most common site of primary cancer in humans, and generally arises in a background of cirrhosis and inflammation. Moreover, the liver is frequently colonized by metastases from cancers of other organs (particularly the colon) because of its anatomical location and organization, as well as its unique metabolic and immunosuppressive environment. In this Review, we discuss how the hepatic microenvironment adapts to pathologies characterized by chronic inflammation and metabolic alterations. We illustrate how these immunological or metabolic changes alter immunosurveillance and thus hinder or promote the development of primary liver cancer. In addition, we describe how inflammatory and metabolic niches affect the spreading of cancer metastases into or within the liver. Finally, we review the current therapeutic options in this context and the resulting challenges that must be surmounted.

ARRB1 suppresses the activation of hepatic macrophages via modulating endoplasmic reticulum stress in lipopolysaccharide-induced acute liver injury

Acute liver injury (ALI) caused by multiple inflammatory responses is a monocyte-/macrophage-mediated liver injury that is associated with high morbidity and mortality. Liver macrophage activation is a vital event that triggers ALI. However, the mechanism of liver macrophage activation has not been fully elucidated. This study examined the role of β-arrestin1 (ARRB1) in wild-type (WT) and ARRB1-knockout (ARRB1-KO) mouse models of ALI induced by lipopolysaccharide (LPS), and ARRB1-KO mice exhibited more severe inflammatory injury and liver macrophage activation compared to WT mice. We found that LPS treatment reduced the expression level of ARRB1 in Raw264.7 and THP-1 cell lines, and mouse primary hepatic macrophages. Overexpression of ARRB1 in Raw264.7 and THP-1 cell lines significantly attenuated LPS-induced liver macrophage activation, such as transformation in cell morphology and enhanced expression of proinflammatory cytokines (tumor necrosis factor-α, interleukin-1β, and interleukin-6), while downregulation of ARRB1 by small interfering RNA and ARRB1 deficiency in primary hepatic macrophages both aggravated macrophage activation. Moreover, overexpression of ARRB1 suppressed LPS-induced endoplasmic reticulum (ER) stress in liver macrophages, and inhibition of ER stress impeded excessive hepatic macrophage activation induced by downregulation of ARRB1. Our data demonstrate that ARRB1 relieves LPS-induced ALI through the ER stress pathway to regulate hepatic macrophage activation and that ARRB1 may be a potential therapeutic target for ALI.

Endoplasmic reticulum stress: Multiple regulatory roles in hepatocellular carcinoma

BACKGROUND

Endoplasmic reticulum (ER) stress is a basic cellular stress response that maintains cellular protein homeostasis under endogenous or exogenous stimuli, which depends on the stimulus, its intensity, and action time. The ER produces a corresponding cascade reaction for crosstalk of adaptive and/or pro-death regulation with other organelles. Hepatocellular carcinoma(HCC) is one of the most common malignant solid tumors with an extremely poor prognosis. Viral hepatitis infection, cirrhosis, and steatohepatitis are closely related to the occurrence and development of HCC, and ER stress has gradually been shown to be a major mechanism. Moreover, an increasing need for protein and lipid products and relative deficiencies of oxygen and nutrients for rapid proliferation and endoplasmic reticulum stress are undoubtedly involved. Therefore, to fully and comprehensively understand the regulatory role of endoplasmic reticulum stress in the occurrence and progression of HCC is of vital importance to explore its pathogenesis and develop novel anti-cancer strategies.

METHODOLOGY

We searched for relevant publications in the PubMed databases using the keywords "Endoplasmic reticulum stress", "hepatocellular carcinoma" in last five years,and present an overview of the current knowledge that links ER stress and HCC, which includes carcinogenesis, progression, and anti-cancer strategies, and propose directions of future research.

RESULT

ER stress were confirmed to be multiple regulators or effectors of cancer, which also be confirmed to drive tumorigenesis and progression of HCC. Targeting ER stress signaling pathway and related molecules could play a critical role for anti-HCC and has become a research hotspot for anti-cancer in recent years.

CONCLUSION

ER stress are critical for the processes of the tumorigenesis and progression of tumors. For HCC, ER stress was associated with tumorigenesis, development, metastasis, angiogenesis and drug resistance, targeting ER stress has emerged as a potential anti-tumor strategy.

Single-cell RNA sequencing shows the immunosuppressive landscape and tumor heterogeneity of HBV-associated hepatocellular carcinoma

Interaction between tumor cells and immune cells in the tumor microenvironment is important in cancer development. Immune cells interact with the tumor cells to shape this process. Here, we use single-cell RNA sequencing analysis to delineate the immune landscape and tumor heterogeneity in a cohort of patients with HBV-associated human hepatocellular carcinoma (HCC). We found that tumor-associated macrophages suppress tumor T cell infiltration and TIGIT-NECTIN2 interaction regulates the immunosuppressive environment. The cell state transition of immune cells towards a more immunosuppressive and exhaustive status exemplifies the overall cancer-promoting immunocellular landscape. Furthermore, the heterogeneity of global molecular profiles reveals co-existence of intra-tumoral and inter-tumoral heterogeneity, but is more apparent in the latter. This analysis of the immunosuppressive landscape and intercellular interactions provides mechanistic information for the design of efficacious immune-oncology treatments in hepatocellular carcinoma.

Single-cell RNA sequencing shows the immunosuppressive landscape and tumor heterogeneity of HBV-associated hepatocellular carcinoma

Interaction between tumor cells and immune cells in the tumor microenvironment is important in cancer development. Immune cells interact with the tumor cells to shape this process. Here, we use single-cell RNA sequencing analysis to delineate the immune landscape and tumor heterogeneity in a cohort of patients with HBV-associated human hepatocellular carcinoma (HCC). We found that tumor-associated macrophages suppress tumor T cell infiltration and TIGIT-NECTIN2 interaction regulates the immunosuppressive environment. The cell state transition of immune cells towards a more immunosuppressive and exhaustive status exemplifies the overall cancer-promoting immunocellular landscape. Furthermore, the heterogeneity of global molecular profiles reveals co-existence of intra-tumoral and inter-tumoral heterogeneity, but is more apparent in the latter. This analysis of the immunosuppressive landscape and intercellular interactions provides mechanistic information for the design of efficacious immune-oncology treatments in hepatocellular carcinoma.

Chemically based transmissible ER stress protocols are unsuitable to study cell-to-cell UPR transmission

Renal epithelial cells regulate the destructive activity of macrophages and participate in the progression of kidney diseases. Critically, the Unfolded Protein Response (UPR), which is activated in renal epithelial cells in the course of kidney injury, is required for the optimal differentiation and activation of macrophages. Given that macrophages are key regulators of renal inflammation and fibrosis, we suppose that the identification of mediators that are released by renal epithelial cells under Endoplasmic Reticulum (ER) stress and transmitted to macrophages is a critical issue to address. Signals leading to a paracrine transmission of ER stress (TERS) from a donor cell to a recipient cells could be of paramount importance to understand how ER-stressed cells shape the immune microenvironment. Critically, the vast majority of studies that have examined TERS used thaspigargin as an inducer of ER stress in donor cells in cellular models. By using multiple sources of ER stress, we evaluated if human renal epithelial cells undergoing ER stress can transmit the UPR to human monocyte-derived macrophages and if such TERS can modulate the inflammatory profiles of these cells. Our results indicate that carry-over of thapsigargin is a confounding factor in chemically based TERS protocols classically used to induce ER Stress in donor cells. Hence, such protocols are not suitable to study the TERS phenomenon and to identify its mediators. In addition, the absence of TERS transmission in more physiological models of ER stress indicates that cell-to-cell UPR transmission is not a universal feature in cultured cells.

The prospects of nanotherapeutic approaches for targeting tumor-associated macrophages in oral cancer

OSCC (oral squamous cell carcinoma) is currently one of the most formidable cancers plagued by challenges like low overall survivability, lymph node associated metastasis, drug resistance, and poor diagnostics. The tumor microenvironment (TME) and its constituent stromal elements are crucial modulators of tumor growth and treatment response, more specifically so with regards to resident tumor associated macrophages (TAMs) and their liaison with the different stromal elements in the tumor niche (Figure 1). Interestingly, there isn't much information on TAM-targeted nanotherapy in OSCC where the first line of therapeutics for oral cancer is surgery with other therapeutics such as chemo- and radiotherapy acting only as adjuvant therapy for oral cancer. In the face of this real time situation, there have been some successful attempts at targeted therapy for OSCC cells and we believe they might elicit favorable responses against TAMs as well. Demanding our immediate attention, this review intends to provide a glimpse of the prevailing anti-TAM treatment strategies, which present great prospect for an uncharted territory like OSCC.

An essential technique for modern hepato-pancreato-biliary surgery: minimally invasive biliary reconstruction

Introduction: Minimally invasive reconstruction of the biliary tract is complex and involves multiple steps. The procedure is challenging and has been an essential technique in modern hepato-pancreato-biliary surgery in recent years. Additionally, the quality of the reconstruction directly affects long-and short-term complications and affects the prognosis and quality of life. Various minimally invasive reconstruction methods have been developed to improve the reconstruction effect; however, the optimal method remains controversial. Areas covered: In this study, were viewed published studies of minimally invasive biliary reconstruction within the last 5 years and discussed the current status and main complications of minimally invasive biliary reconstruction. More importantly, we introduced the current reconstruction strategies and technical details of minimally invasive biliary reconstruction, which may be potentially helpful for surgeons to choose reconstruction methods and improve reconstruction quality. Expert opinion: Although several improved and modified methods for biliary reconstruction have been developed recently, no single approach is optimal or adaptable to all situations. Patient-specific selection of appropriate technical strategies according to different situations combined with sophisticated and skilled minimally invasive techniques effectively improves the quality of anastomosis and reduces complications.

The HSP GRP94 interacts with macrophage intracellular complement C3 and impacts M2 profile during ER stress

The role of GRP94, an endoplasmic reticulum (ER) stress protein with both pro- and anti-inflammatory functions, has not been investigated in macrophages during ER stress, whereas ER stress has been reported in many diseases involving macrophages. In this work, we studied GRP94 in M1/LPS + IFNγ and M2/IL-4 primary macrophages derived from human monocytes (isolated from buffy coats), in basal and ER stress conditions induced by thapsigargin (Tg), an inducer of ER calcium depletion and tunicamycin (Tm), an inhibitor of N-glycosylation. We found that GRP94 was expressed on the membrane of M2 but not M1 macrophages. In M2, Tg, but not Tm, while decreased GRP94 content in the membrane, it induced its secretion. This correlated with the induction of a pro-inflammatory profile, which was dependent on the UPR IRE1α arm activation and on a functional GRP94. As we previously reported that GRP94 associated with complement C3 at the extracellular level, we analyzed C3 and confirmed GRP94-C3 interaction in our experimental model. Further, Tg increased this interaction and, in these conditions, C3b and cathepsin L were detected in the extracellular medium where GRP94 co-immunoprecipitated with C3 and C3b. Finally, we showed that the C3b inactivated fragment, iC3b, only present on non-stressed M2, depended on functional GRP94, making both GRP94 and iC3b potential markers of M2 cells. In conclusion, our results show that GRP94 is co-secreted with C3 under ER stress conditions which may facilitate its cleavage by cathepsin L, thus contributing to the pro-inflammatory profile observed in stressed M2 macrophages.

Transmissible Endoplasmic Reticulum Stress: A Novel Perspective on Tumor Immunity

As the first compartment of the protein secretory pathway, the endoplasmic reticulum (ER) acts as a protein synthesis factory, maintaining proteostasis and ER homeostasis. However, a variety of intrinsic and extrinsic perturbations, such as cancer, can disrupt the homeostasis and result in a large accumulation of misfolded/unfolded proteins in the ER lumen, thereby provoking a specific cellular state addressed as “ER stress”. Then the unfolded protein response (UPR), an adaptive signaling pathway, is triggered to address the stress and restore the homeostasis. A novel aspect of ER stress is that it can be transmitted from cancer cells to tumor-infiltrating myeloid cells through certain cancer cell-released soluble factors, which is termed as transmissible ER stress (TERS) or ER stress resonance (ERSR). In this review, we provide a comprehensive overview of the link between cancer and ER stress as well as the possible soluble factors mediating TERS. We further elaborate the cell-extrinsic effects of TERS on tumor immunity, and how it indirectly modulates cancer development and progression, which is expected to add a new dimension to anticancer therapy.

Golgi protein-73: A biomarker for assessing cirrhosis and prognosis of liver disease patients

BACKGROUND

Reliable biomarkers of cirrhosis, hepatocellular carcinoma (HCC), or progression of chronic liver diseases are missing. In this context, Golgi protein-73 (GP73) also called Golgi phosphoprotein-2, was originally defined as a resident Golgi type II transmembrane protein expressed in epithelial cells. As a result, GP73 expression was found primarily in biliary epithelial cells, with only slight detection in hepatocytes. However, in patients with acute or chronic liver diseases and especially in HCC, the expression of GP73 is significantly up-regulated in hepatocytes. So far, few studies have assessed GP73 as a diagnostic or prognostic marker of liver fibrosis and disease progression.

AIM

To assess serum GP73 efficacy as a diagnostic marker of cirrhosis and/or HCC or as predictor of liver disease progression.

METHODS

GP73 serum levels were retrospectively determined by a novel GP73 ELISA (QUANTA Lite® GP73, Inova Diagnostics, Inc., Research Use Only) in a large cohort of 632 consecutive patients with chronic viral and non-viral liver diseases collected from two tertiary Academic centers in Larissa, Greece (n = 366) and Debrecen, Hungary (n = 266). Aspartate aminotransferase (AST)/Platelets (PLT) ratio index (APRI) was also calculated at the relevant time points in all patients. Two hundred and three patients had chronic hepatitis B, 183 chronic hepatitis C, 198 alcoholic liver disease, 28 autoimmune cholestatic liver diseases, 15 autoimmune hepatitis, and 5 with other liver-related disorders. The duration of follow-up was 50 (57) mo [median (interquartile range)]. The development of cirrhosis, liver decompensation and/or HCC during follow-up were assessed according to internationally accepted guidelines. In particular, the surveillance for the development of HCC was performed regularly with ultrasound imaging and alpha-fetoprotein (AFP) determination every 6 mo in cirrhotic and every 12 mo in non-cirrhotic patients.

RESULTS

Increased serum levels of GP73 (> 20 units) were detected at initial evaluation in 277 out of 632 patients (43.8%). GP73-seropositivity correlated at baseline with the presence of cirrhosis (96.4% vs 51.5%, P < 0.001), decompensation of cirrhosis (60.3% vs 35.5%, P < 0.001), presence of HCC (18.4% vs 7.9%, P < 0.001) and advanced HCC stage (52.9% vs 14.8%, P = 0.002). GP73 had higher diagnostic accuracy for the presence of cirrhosis compared to APRI score [Area under the curve (AUC) (95%CI): 0.909 (0.885-0.934) vs 0.849 (0.813-0.886), P = 0.003]. Combination of GP73 with APRI improved further the accuracy (AUC: 0.925) compared to GP73 (AUC: 0.909, P = 0.005) or APRI alone (AUC: 0.849, P < 0.001). GP73 levels were significantly higher in HCC patients compared to non-HCC [22.5 (29.2) vs 16 (20.3) units, P < 0.001) and positively associated with BCLC stage [stage 0: 13.9 (10.8); stage A: 17.1 (16.8); stage B: 19.6 (22.3); stage C: 32.2 (30.8); stage D: 45.3 (86.6) units, P < 0.001] and tumor dimensions [very early: 13.9 (10.8); intermediate: 19.6 (18.4); advanced: 29.1 (33.6) units, P = 0.004]. However, the discriminative ability for HCC diagnosis was relatively low [AUC (95%CI): 0.623 (0.570-0.675)]. Kaplan-Meier analysis showed that the detection of GP73 in patients with compensated cirrhosis at baseline, was prognostic of higher rates of decompensation (P = 0.036), HCC development (P = 0.08), and liver-related deaths (P < 0.001) during follow-up.

CONCLUSION

GP73 alone appears efficient for detecting cirrhosis and superior to APRI determination. In combination with APRI, its diagnostic performance can be further improved. Most importantly, the simple GP73 measurement proved promising for predicting a worse outcome of patients with both viral and non-viral chronic liver diseases.

Progress and prospects of biomarkers in primary liver cancer (Review)

Tumor biomarkers are important in the early screening, diagnosis, therapeutic evaluation, recurrence and prognosis prediction of tumors. Primary liver cancer is one of the most common malignant tumors; it has high incidence and mortality rates and seriously endangers human health. The main pathological types of primary liver cancer include hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC) and combined HCC‑cholangiocarcinoma (cHCC‑CC). In the present review, a systematic outline of the current biomarkers of primary liver cancer is presented, from conventional blood biomarkers, histochemical biomarkers and potential biomarkers to resistance‑associated biomarkers. The important relationships are deeply elucidated between biomarkers and diagnosis, prognosis, clinicopathological features and resistance, as well as their clinical significance, in patients with the three main types of primary liver cancer. Moreover, a summary of several important biomarker signaling pathways is provided, which is helpful for studying the biological mechanism of liver cancer. The purpose of this review is to provide help for clinical or medical researchers in the early diagnosis, differential diagnosis, prognosis and treatment of HCC.

Combined and sequential non-invasive approach to diagnosing non-alcoholic steatohepatitis in patients with non-alcoholic fatty liver disease and persistently normal alanine aminotransferase levels

BACKGROUND AND AIM

Imaging-confirmed non-alcoholic fatty liver disease (NAFLD) with normal alanine aminotransferase (nALT) levels is infrequently the subject for further evaluation. Early diagnosis of non-alcoholic steatohepatitis (NASH) is needed to prevent disease progression. Thus, we tested the clinical utility of serum Golgi protein 73 (GP73) levels and developed a new non-invasive score to diagnose NASH in patients with biopsy-confirmed NAFLD and persistent nALT levels.

METHODS

Serum GP73 and cytokeratin-18 M30 fragments (CK18-M30) levels were measured in 345 patients with biopsy-proven NAFLD. We developed a new score, named G-NASH model (by incorporating serum GP73), and combined it with serum CK18-M30 measurement in a sequential non-invasive approach to accurately identify NASH among patients with NAFLD and persistent nALT levels.

RESULTS

105 (30.4%) patients had persistent nALT, 53 of whom had histologically confirmed NASH. Both serum GP73 and CK18-M30 levels alone had poor diagnostic accuracy in identifying NASH (55.2% and 51.6%, respectively) in these patients. Conversely, G-NASH model performed better than other established non-invasive scoring systems, and by using our proposed sequential non-invasive approach 82.9% of patients with NASH were correctly identified.

CONCLUSIONS

NASH is highly prevalent in patients with NAFLD with persistent nALT levels. The G-NASH model accurately identifies NASH in this patient group.