Oncostatin M up-regulates the ER chaperone Grp78/BiP in liver cells

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

PURPOSE

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

EXPERIMENTAL DESIGN

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

RESULTS

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

CONCLUSIONS

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

Oncostatin M: From Intracellular Signaling to Therapeutic Targets in Liver Cancer

Primary liver cancers represent the third-most-common cause of cancer-related mortality worldwide, with an incidence of 80-90% for hepatocellular carcinoma (HCC) and 10-15% for cholangiocarcinoma (CCA), and an increasing morbidity and mortality rate. Although HCC and CCA originate from independent cell populations (hepatocytes and biliary epithelial cells, respectively), they develop in chronically inflamed livers. Evidence obtained in the last decade has revealed a role for cytokines of the IL-6 family in the development of primary liver cancers. These cytokines operate through the receptor subunit gp130 and the downstream Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathways. Oncostatin M (OSM), a member of the IL-6 family, plays a significant role in inflammation, autoimmunity, and cancer, including liver tumors. Although, in recent years, therapeutic approaches for the treatment of HCC and CCA have been implemented, limited treatment options with marginal clinical benefits are available. We discuss how OSM-related pathways can be selectively inhibited and therapeutically exploited for the treatment of liver malignancies.

ISG15 Promotes ERK1 ISGylation, CD8+ T Cell Activation and Suppresses Ovarian Cancer Progression

Increased number of tumor-infiltrating CD8+ lymphocytes is associated with improved survival in patients with advanced stage high grade serous ovarian cancer (HGSOC) but the underlying molecular mechanism has not been thoroughly explored. Using transcriptome profiling of microdissected HGSOC tissue with high and low CD8+ lymphocyte count and subsequent validation studies, we demonstrated that significantly increased ISG15 (Interferon-stimulated gene 15) expression in HGSOC was associated with high CD8+ lymphocyte count and with the improvement in median overall survival in both univariate and multivariate analyses. Further functional studies showed that endogenous and exogenous ISG15 suppressed ovarian cancer progression through ISGylation of ERK in HGSOC, and activation of NK cells and CD8+ T lymphocytes. These data suggest that the development of treatment strategies based on up-regulating ISG15 in ovarian cancer cells or increased circulating ISG15 in ovarian cancer patients is warranted.

Prostaglandin E1 protects hepatocytes against endoplasmic reticulum stress-induced apoptosis via protein kinase A-dependent induction of glucose-regulated protein 78 expression

AIM

To investigate the protective effect of prostaglandin E1 (PGE1) against endoplasmic reticulum (ER) stress-induced hepatocyte apoptosis, and to explore its underlying mechanisms.

METHODS

Thapsigargin (TG) was used to induce ER stress in the human hepatic cell line L02 and hepatocarcinoma-derived cell line HepG2. To evaluate the effects of PGE1 on TG-induced apoptosis, PGE1 was used an hour prior to TG treatment. Activation of unfolded protein response signaling pathways were detected by western blotting and quantitative real-time RT-PCR. Apoptotic index and cell viability of L02 cells and HepG2 cells were determined with flow cytometry and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay.

RESULTS

Pretreatment with 1 μmol/L PGE1 protected against TG-induced apoptosis in both L02 cells and HepG2 cells. PGE1 enhanced the TG-induced expression of C/EBP homologous protein (CHOP), glucose-regulated protein (GRP) 78 and spliced X box-binding protein 1 at 6 h. However, it attenuated their expressions after 24 h. PGE1 alone induced protein and mRNA expressions of GRP78; PGE1 also induced protein expression of DNA damage-inducible gene 34 and inhibited the expressions of phospho-PKR-like ER kinase, phospho-eukaryotic initiation factor 2α and CHOP. Treatment with protein kinase A (PKA)-inhibitor H89 or KT5720 blocked PGE1-induced up-regulation of GRP78. Further, the cytoprotective effect of PGE1 on hepatocytes was not observed after blockade of GRP78 expression by H89 or small interfering RNA specifically targeted against human GRP78.

CONCLUSION

Our study demonstrates that PGE1 protects against ER stress-induced hepatocyte apoptosis via PKA pathway-dependent induction of GRP78 expression.

Crosstalk between different family members: IL27 recapitulates IFNγ responses in HCC cells, but is inhibited by IL6-type cytokines

Interleukin-27 (IL27) is a type-I-cytokine of the IL6/IL12 family predominantly secreted by activated macrophages and dendritic cells. In the liver, IL27 expression was observed to be upregulated in patients with hepatitis B, and sera of hepatocellular carcinoma (HCC) patients contain significantly elevated levels of IL27 compared to healthy controls or patients with hepatitis and/or liver cirrhosis. In this study, we show that IL27 induces STAT1 and STAT3 phosphorylation in 5 HCC lines and 3 different types of non-transformed liver cells. We were especially interested in the relevance of the IL27-induced STAT3 activation in liver cells. Thus, we compared the IL27 responses with those induced by IFNγ (STAT1-dominated response) or IL6-type cytokines (IL6, hyper-IL6 (hy-IL6) or OSM) (STAT3-dominated response) by microarray analysis and find that in HCC cells, IL27 induces an IFNγ-like, STAT1-dependent transcriptional response, but we do not find an effective STAT3-dependent response. Validation experiments corroborate the finding from the microarray evaluation. Interestingly, the availability of STAT1 seems critical in the shaping of the IL27 response, as the siRNA knock-down of STAT1 revealed the ability of IL27 to induce the acute-phase protein γ-fibrinogen, a typical IL6 family characteristic. Moreover, we describe a crosstalk between the signaling of IL6-type cytokines and IL27: responses to the gp130-engaging cytokine IL27 (but not those to IFNs) can be inhibited by IL6-type cytokine pre-stimulation, likely by a SOCS3-mediated mechanism. Thus, IL27 recapitulates IFNγ responses in liver cells, but differs from IFNγ by its sensitivity to SOCS3 inhibition.

Inhibitory effect of STAT3 gene combined with CDDP on growth of human Wilms tumour SK-NEP-1 cells

To investigate the effects of signal transducer and activator of transcription 3 (STAT3) combined with cisplatin (CDDP) on the growth of human Wilms tumour (WT) SK-NEP-1 cell subcutaneous xenografts in nude mice and the possible mechanisms. Human WT SK-NEP-1 cells were subcutaneously transplanted to establish the BALB/c nude mice xenograft model. Mice were randomly divided into five groups: blank control group, adenovirus control group (NC group), STAT3 group, CDDP group and STAT3 plus CDDP group (combination group). Tumour volume and tumour weight were observed during the therapeutic process. The expression levels of STAT3, glucose regulatory protein 78 (GRP78) and BCL2-associated X protein (BAX) were evaluated by immunohistochemical analysis. Compared with the STAT3 group or CDDP group, the tumour weight and volume was significantly reduced in the combination group (P<0.05). No statistical significance was found in NC group compared with the blank control group (P > 0.05). Immunohistochemical analysis showed that STAT3, GRP78 and BAX protein levels in the combination group were significantly higher than those in STAT3 group and CDDP group (P<0.05). Exogenous STAT3 and CDDP may synergistically inhibit the xenograft tumour growth through up-regulation of BAX protein via GRP78.

Molecular Cloning and mRNA Expression of Heat Shock Protein Genes and Their Response to Cadmium Stress in the Grasshopper Oxya chinensis

Heat shock proteins (Hsps) are highly conserved molecular chaperones that are synthesized in response to stress. In this study, we cloned the full-length sequences of the Grp78 (glucose-regulated protein 78), Hsp70, Hsp90, and Hsp40 genes from the Chinese rice grasshopper Oxya chinensis. The full-length cDNA sequences of OcGrp78, OcHsp70, OcHsp90, and OcHsp40 contain open reading frames of 1947, 1920, 2172, and 1042 bp that encode proteins of 649, 640, 724, and 347 amino acids, respectively. Fluorescent real-time quantitative PCR (RT-qPCR) was performed to quantify the relative transcript levels of these Hsp genes in different tissues and developmental stages. The mRNAs encoding these four Hsp genes were present at all developmental stages and in all tissues examined but were expressed at varying levels. Additionally, we investigated the mRNA expression profiles of these four Hsps in O. chinensis subjected to Cadmium (Cd) stress. OcGrp78, OcHsp70, OcHsp90, and OcHsp40 mRNA expression was induced under acute Cd stress; the levels reached a maximum within a short time (6 h), were reduced significantly at 12 h, and were lowered to or below control levels by 48 h. Regarding induction efficiency, OcHsp70 was the most sensitive gene to acute Cd stress. Chronic Cd exposure showed that dietary Cd treatment induced increased OcGrp78, OcHsp90, and OcHsp40 expression. However, dietary Cd induced a significant reduction of OcHsp70 expression. In the period tested, no significant difference in the mortality of the grasshoppers was observed. Our results suggest that these four Hsps genes, especially OcHsp70, are sensitive to acute Cd stress and could be used as molecular markers for toxicology studies. However, our results also indicate that OcHsp70 is not suitable for use as a molecular marker of chronic Cd contamination.

PERK-dependent activation of JAK1 and STAT3 contributes to endoplasmic reticulum stress-induced inflammation

Neuroinflammation and endoplasmic reticulum (ER) stress are associated with many neurological diseases. Here, we have examined the interaction between ER stress and JAK/STAT-dependent inflammation in glial cells. We show that ER stress is present in the central nervous system (CNS) concomitant with inflammation and astrogliosis in the multiple sclerosis (MS) mouse model of experimental autoimmune encephalomyelitis (EAE). Astrocytes do not easily succumb to ER stress but rather activate an inflammatory program involving activation of STAT3 in a JAK1-dependent fashion. ER stress-induced activation of the JAK1/STAT3 axis leads to expression of interleukin 6 (IL-6) and several chemokines. Moreover, the activation of STAT3 signaling is dependent on PERK, a central component of the ER stress response, which we show is phosphorylated by JAK1. Disruption of PERK abrogates ER stress-induced activation of STAT3 and subsequent gene expression. Additionally, ER-stressed astrocytes, via paracrine signaling, can stimulate activation of microglia, leading to production of IL-6 and oncostatin M (OSM). These IL-6 cytokines can then synergize with ER stress in astrocytes to drive inflammation. Together, this work describes a new PERK/JAK1/STAT3 signaling pathway that elicits a feed-forward inflammatory loop involving astrocytes and microglia to drive neuroinflammation, which may be relevant in diseases such as MS.

IL-6 and related cytokines as the critical lynchpins between inflammation and cancer

Inflammatory responses play pivotal roles in cancer development, including tumor initiation, promotion, progression, and metastasis. Cytokines are now recognized as important mediators linking inflammation and cancer, and are therefore potential therapeutic and preventive targets as well as prognostic factors. The interleukin (IL)-6 family of cytokines, especially IL-6 and IL-11, is highly up-regulated in many cancers and considered as one of the most important cytokine families during tumorigenesis and metastasis. This review discusses molecular mechanisms linking the IL-6 cytokine family to solid malignancies and their treatment.

Glucose regulated protein 78: a critical link between tumor microenvironment and cancer hallmarks

Glucose regulated protein 78 (GRP78) has long been recognized as a molecular chaperone in the endoplasmic reticulum (ER) and can be induced by the ER stress response. Besides its location in the ER, GRP78 has been found to be present in cell plasma membrane, cytoplasm, mitochondria, nucleus as well as cellular secretions. GRP78 is implicated in tumor cell proliferation, apoptosis resistance, immune escape, metastasis and angiogenesis, and its elevated expression usually correlates with a variety of tumor microenvironmental stresses, including hypoxia, glucose deprivation, lactic acidosis and inflammatory response. GRP78 protein acts as a centrally located sensor of stress, which feels and adapts to the alteration in the tumor microenvironment. This article reviews the potential contributions of GRP78 to the acquisition of cancer hallmarks based on intervening in stress responses caused by tumor niche alterations. The paper also introduces several potential GRP78 relevant targeted therapies.