Grp78 promotes the invasion of hepatocellular carcinoma

Impact of Obesity-Related Endoplasmic Reticulum Stress on Cancer and Associated Molecular Targets

Obesity, characterized by excessive body fat, is closely linked to endoplasmic reticulum (ER) stress, leading to insulin resistance and type 2 diabetes. Inflammatory pathways like c-Jun N-terminal kinase (JNK) worsen insulin resistance, impacting insulin signaling. Moreover, ER stress plays a substantial role in cancer, influencing tumor cell survival and growth by releasing factors like vascular endothelial growth factor (VEGF). The unfolded protein response (UPR) is pivotal in this process, offering both pro-survival and apoptotic pathways. This review offers an extensive exploration of the sophisticated connection between ER stress provoked by obesity and its role in both the onset and advancement of cancer. It delves into the intricate interplay between oncogenic signaling and the pathways associated with ER stress in individuals who are obese. Furthermore, this review sheds light on potential therapeutic strategies aimed at managing ER stress induced by obesity, with a focus on addressing cancer initiation and progression. The potential to alleviate ER stress through therapeutic interventions, which may encompass the use of small molecules, FDA-approved medications, and gene therapy, holds great promise. A more in-depth examination of pathways such as UPR, ER-associated protein degradation (ERAD), autophagy, and epigenetic regulation has the potential to uncover innovative therapeutic approaches and the identification of predictive biomarkers.

Decoding the roles of heat shock proteins in liver cancer

Hepatocellular carcinoma (HCC) is one of the most common gastrointestinal malignancies, characterized by insidious onset and high propensity for metastasis and recurrence. Apart from surgical resection, there are no effective curative methods for HCC in recent years, due to resistance to radiotherapy and chemotherapy. Heat shock proteins (HSP) play a crucial role in maintaining cellular homeostasis and normal organism development as molecular chaperones for intracellular proteins. Both basic research and clinical data have shown that HSPs are crucial participants in the HCC microenvironment, as well as the occurrence, development, metastasis, and resistance to radiotherapy and chemotherapy in various malignancies, particularly liver cancer. This review aims to discuss the molecular mechanisms and potential clinical value of HSPs in HCC, which may provide new insights for HSP-based therapeutic interventions for HCC.

Targeting PAK4 reverses cisplatin resistance in NSCLC by modulating ER stress

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

Synergism in actions of HBV with aflatoxin in cancer development

Aflatoxin B1 (AFB1) is a fungal metabolite found in animal feeds and human foods. It is one of the most toxic and carcinogenic of aflatoxins and is classified as a Group 1 carcinogen. Dietary exposure to AFB1 and infection with chronic Hepatitis B Virus (HBV) make up two of the major risk factors for hepatocellular carcinoma (HCC). These two major risk factors raise the probability of synergism between the two agents. This review proposes some collaborative molecular mechanisms underlying the interaction between AFB1 and HBV in accelerating or magnifying the effects of HCC. The HBx viral protein is one of the main viral proteins of HBV and has many carcinogenic qualities that are involved with HCC. AFB1, when metabolized by CYP450, becomes AFB1-exo-8,9-epoxide (AFBO), an extremely toxic compound that can form adducts in DNA sequences and induce mutations. With possible synergisms that exist between HBV and AFB1 in mind, it is best to treat both agents simultaneously to reduce the risk by HCC.

Expression of GRP78 and its copartners in HEK293 and pancreatic cancer cell lines (BxPC-3/PANC-1) exposed to MRI and CT contrast agents

Endoplasmic reticulum (ER) stress-associated chaperones trigger a defense mechanism called as unfolded protein response (UPR) which can manage apoptosis and be determinative in cell fate. Both anticancer drug effects and potential toxicity effects of magnetic resonance imaging (MRI) and computed tomography (CT) contrast agents were aimed to be evaluated. For this purpose, we investigated expression profiles of endoplasmic reticulum stress-associated chaperone molecules in human pancreatic tumor lines BxPC-3 and PANC-1 and control human embryonic kidney cells 293 (HEK293) induced with a variety of gadolinium and iohexol contrast agents. Protein expression levels of ER stress-associated chaperones (master regulator: GRP78/Bip and its copartners: Calnexin, Ero1, PDI, CHOP, IRE1α and PERK) were evaluated with Western blotting. Expression levels at mRNA level were also assessed for GRP78/Bip and CHOP with real-time PCR. Induction of cells was carried out with four different Gd-based contrast agents (GBCAs): (Dotarem, Optimark, Primovist and Gadovist) and two different iohexol agents (Omnipol, Omnipaque). CT contrast agents tested in the study did not result in significant ER stress in HEK293 cells. However, they do not seem to have theranostic potential in pancreas cancer through ER pathway. The potential efficiency of macrocyclic MRI contrast agents to provoke apoptosis via ER stress-associated chaperones in BxPC-3 cells lends credibility for their future theranostic use in pancreas cancer as long as undesired toxicity effects were carefully considered. ER stress markers and/or contrast agents seem to have promising potential to be translated into the clinical practice to manage pancreas cancer progression.

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

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

Comparative RNA-Sequencing Analysis Reveals High Complexity and Heterogeneity of Transcriptomic and Immune Profiles in Hepatocellular Carcinoma Tumors of Viral (HBV, HCV) and Non-Viral Etiology

Background and Objectives: Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is the leading cause of cancer-related mortality. It arises and progresses against fibrotic or cirrhotic backgrounds mainly due to infection with hepatitis viruses B (HBV) or C (HCV) or non-viral causes that lead to chronic inflammation and genomic changes. A better understanding of molecular and immune mechanisms in HCC subtypes is needed. Materials and Methods: To identify transcriptional changes in primary HCC tumors with or without hepatitis viral etiology, we analyzed the transcriptomes of 24 patients by next-generation sequencing. Results: We identified common and unique differentially expressed genes for each etiological tumor group and analyzed the expression of SLC, ATP binding cassette, cytochrome 450, cancer testis, and heat shock protein genes. Metascape functional enrichment analysis showed mainly upregulated cell-cycle pathways in HBV and HCV and upregulated cell response to stress in non-viral infection. GeneWalk analysis identified regulator, hub, and moonlighting genes and highlighted CCNB1, ACTN2, BRCA1, IGF1, CDK1, AURKA, AURKB, and TOP2A in the HCV group and HSF1, HSPA1A, HSP90AA1, HSPB1, HSPA5, PTK2, and AURKB in the group without viral infection as hub genes. Immune infiltrate analysis showed that T cell, cytotoxic, and natural killer cell markers were significantly more highly expressed in HCV than in non-viral tumors. Genes associated with monocyte activation had the highest expression levels in HBV, while high expression of genes involved in primary adaptive immune response and complement receptor activity characterized tumors without viral infection. Conclusions: Our comprehensive study underlines the high degree of complexity of immune profiles in the analyzed groups, which adds to the heterogeneous HCC genomic landscape. The biomarkers identified in each HCC group might serve as therapeutic targets.

Regulation of endoplasmic reticulum stress by hesperetin: Focus on antitumor and cytoprotective effects

BACKGROUND

Cancer is still an all-times issue due to a large and even increasing number of deaths. Impaired genes regulating cell proliferation and apoptosis are targets for the development of novel cancer treatments.

HYPOTHESIS

Increased transcription of NADPH oxidase activator (NOXA), Bcl2-like11 (BIM), BH3-only proteins and p53 unregulated apoptosis modulator (PUMA) is caused by the imbalance between pro- and anti-apoptotic Bcl-2 proteins due to endoplasmic reticulum (ER) stress. The membranous network of ER is present in all eukaryotic cells. ER stress facilitates the interaction between Bax and PUMA, triggering the release of cytochrome C. As a main intracellular organelle, ER is responsible for translocation as well as post-translation modification and protein folding.

RESULTS

Hesperetin is a cytoprotective flavonone, which acts against ER stress and protects from cell damage induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Hesperetin inhibits lipid peroxidation induced by Fe²⁺ and l-ascorbic acid in rat brain homogenates.

CONCLUSION

This review deals with the anticancer effects of hesperetin regarding the regulation of ER stress as a principal mechanism in the pathogenesis of tumors.

Ubiquitin-conjugating enzyme E2T promotes tumor stem cell characteristics and migration of cervical cancer cells by regulating the GRP78/FAK pathway

Ubiquitin-conjugating enzyme E2T (UBE2T) functions as an E2 ubiquitin-conjugating enzyme in the ubiquitin-proteasome degradation system and mediates cellular processes, such as cell cycle, proliferation, and differentiation. UBE2T has been considered to be an oncogene in a variety of tumors. However, the oncogenic role of UBE2T in cervical cancer remains unclear. In this study, our results first showed that the expression of UBE2T was higher in both of cervical cancer tissues and cells than that in the normal tissues and cells. Knockdown of UBE2T reduced cervical cancer cell viability and suppressed the proliferation, invasion, and migration. However, overexpression of UBE2T contributed to cervical cancer cell growth and metastasis. Moreover, UBE2T overexpression cervical cancer cells demonstrated enhanced self-renewal capacity with upregulation of SOX2, Oct-4, and Nanog protein. Silencing of UBE2T downregulated protein expression of SOX2, Oct-4, and Nanog in cervical cancer cells reduced self-renewal capacity. Furthermore, ectopic UBE2T expression promoted protein expression of glucose-regulated protein 78 (GRP78) and focal adhesion kinase (FAK) phosphorylation in cervical cancer cells. The knockdown of UBE2T reduced protein expression of GRP78 and FAK phosphorylation. Collectively, UBE2T promoted cervical cancer stem cell traits and exerted an oncogenic role through activation of the GRP78/FAK pathway.

Thymoquinone Potentiated the Anticancer Effect of Cisplatin on Hepatic Tumorigenesis by Modulating Tissue Oxidative Stress and Endoplasmic GRP78/CHOP Signaling

Thymoquinone (TQ) combined with Cisplatin may augment its anticancer effect on hepatocellular carcinoma (HCC), through oxidative stress mitigation and endoplasmic reticulum (ER) protein modulation. Fifty adult male Wistar albino rats were assigned into five equal experimental groups (n = 10); 1) Control, 2) diethylnitrosamine/carbon tetrachloride-induced liver tumorigenesis model (HCC), 3) Cisplatin (2 mg.kg^-1ip) treated rats, 4) Thymoquinone treated group (20 mg.kg^-1oral), and 5) group treated with both drugs as in Groups 3 and 4. Treatment regimens started following model confirmation and continued for 4 weeks. In the HCC model, we detected elevated ER chaperone glucose-regulated protein-78 (GRP78) and reduced C/EBP-homologous protein (CHOP)-mediated apoptosis that was accompanied by the elevated alpha-fetoprotein (AFP) marker and deteriorated liver functions. Our original results indicated that Thymoquinone potentiated the pro-apoptotic effect of cisplatin by modulating GRP78/CHOP signaling. Cisplatin/TQ reduced the elevated GRP78 and induced CHOP-mediated apoptosis in the diseased liver tissues compared to the HCC and Cisplatin treated groups. Cisplatin/TQ combination normalized AFP levels and improved liver functions compared to both HCC and cisplatin groups alone. In conclusion, Thymoquinone enhanced the efficacy of Cisplatin in HCC treatment by modulating the GRP78/CHOP/caspase-3 pathway. Thymoquinone is recommended to achieve greater therapeutic benefits and reduce the cisplatin hepatotoxicity in HCC management.

Endoplasmic Reticulum Stress Provocation by Different Nanoparticles: An Innovative Approach to Manage the Cancer and Other Common Diseases

A proper execution of basic cellular functions requires well-controlled homeostasis including correct protein folding. Endoplasmic reticulum (ER) implements such functions by protein reshaping and post-translational modifications. Different insults imposed on cells could lead to ER stress-mediated signaling pathways, collectively called the unfolded protein response (UPR). ER stress is also closely linked with oxidative stress, which is a common feature of diseases such as stroke, neurodegeneration, inflammation, metabolic diseases, and cancer. The level of ER stress is higher in cancer cells, indicating that such cells are already struggling to survive. Prolonged ER stress in cancer cells is like an Achilles' heel, if aggravated by different agents including nanoparticles (NPs) may be exhausted off the pro-survival features and can be easily subjected to proapoptotic mode. Different types of NPs including silver, gold, silica, graphene, etc. have been used to augment the cytotoxicity by promoting ER stress-mediated cell death. The diverse physico-chemical properties of NPs play a great role in their biomedical applications. Some special NPs have been effectively used to address different types of cancers as these particles can be used as both toxicological or therapeutic agents. Several types of NPs, and anticancer drug nano-formulations have been engineered to target tumor cells to enhance their ER stress to promote their death. Therefore, mitigating ER stress in cancer cells in favor of cell death by ER-specific NPs is extremely important in future therapeutics and understanding the underlying mechanism of how cancer cells can respond to NP induced ER stress is a good choice for the development of novel therapeutics. Thus, in depth focus on NP-mediated ER stress will be helpful to boost up developing novel pro-drug candidates for triggering pro-death pathways in different cancers.

GALNT6 promotes invasion and metastasis of human lung adenocarcinoma cells through O-glycosylating chaperone protein GRP78

Lung adenocarcinoma remains a threat to human health due to its high rate of recurrence and distant metastasis. However, the molecular mechanism underlying lung adenocarcinoma metastasis remains yet incompletely understood. Here, we show that upregulated expression of polypeptide N-acetylgalactosaminyltransferase6 (GALNT6) in lung adenocarcinoma is associated with lymph node metastasis and poor prognosis. In lung adenocarcinoma cells, GALNT6 over-expression promoted epithelial-mesenchymal transition (EMT), wound healing, and invasion which could be significantly reversed by GALNT6 silencing. GALNT6 silencing also mitigated the metastasis of lung adenocarcinoma and prolonged the survival of xenograft tumor-bearing mice. Furthermore, GALNT6 directly interacted with, and O-glycosylated chaperone protein GRP78, which promoted EMT by enhancing the MEK1/2/ERK1/2 signaling in lung cancer cells. Therefore, GALNT6 is emerging as novel positive regulator for the malignancy of human lung adenocarcinoma. Targeting GALNT6-GRP78-MEK1/2/ERK1/2 may thus represent a new avenue to develop therapeutics against lung cancer metastasis.

RHBDD2 overexpression promotes a chemoresistant and invasive phenotype to rectal cancer tumors via modulating UPR and focal adhesion genes

The current standard of care for locally advanced rectal cancer (RC) is neoadjuvant radio-chemotherapy (NRC) with 5-fluorouracil (5Fu) as the main drug, followed by surgery and adjuvant chemotherapy. While a group of patients will achieve a pathological complete response, a significant percentage will not respond to the treatment. The Unfolding Protein Response (UPR) pathway is generally activated in tumors and results in resistance to radio-chemotherapy. We previously showed that RHBDD2 gene is overexpressed in the advanced stages of colorectal cancer (CRC) and that it could modulate the UPR pathway. Moreover, RHBDD2 expression is induced by 5Fu. In this study, we demonstrate that the overexpression of RHBDD2 in CACO2 cell line confers resistance to 5Fu, favors cell migration, adhesion and proliferation and has a profound impact on the expression of both, the UPR genes BiP, PERK and CHOP, and on the cell adhesion genes FAK and PXN. We also determined that RHBDD2 binds to BiP protein, the master UPR regulator. Finally, we confirmed that a high expression of RHBDD2 in RC tumors after NRC treatment is associated with the development of local or distant metastases. The collected evidence positions RHBDD2 as a promising prognostic biomarker to predict the response to neoadjuvant therapy in patients with RC.

Proteomic Profile of Sorafenib Resistance in Hepatocellular Carcinoma; GRP78 Expression Is Associated With Inferior Response to Sorafenib

BACKGROUND/AIM

The outcome of patients with advanced hepatocellular carcinoma (HCC) remains poor and therapeutic options, including sorafenib, the first anti-cancer drug proved to prolong survival in patients with advanced HCC, are limited. However, no clinically useful predictive biomarker for sorafenib has been reported.

MATERIALS AND METHODS

We exploited two-dimensional gel electrophoresis coupled with mass spectrometry to find de-regulated proteins by using conditioning of a sorafenib-resistant HCC cell line, Huh7. Tumor samples from 60 patients with HCC treated with sorafenib were analyzed and correlated with survival outcome.

RESULTS

Comparative proteomics indicated three proteins including, 78 kDa glucose related protein (GRP78), 14-3-3ε, and heat shock protein 90β (HSP90β). The three proteins were over-expressed in sorafenib-resistant Huh7 cells. In HCC tumor samples from patients treated with sorafenib, 73% of tumor samples had a high expression of GRP78, 18% had high 14-3-3ε expression and 85% had high HSP90β expression. Among these, GRP78 was associated with the shortest progression-free survival of HCC patients treated with sorafenib.

CONCLUSION

GRP78 can be a predictive biomarker in HCC patients treated with sorafenib. Strategies designed to inhibit the GRP78-related pathway may overcome sorafenib resistance.

Urinary exosome miR-30c-5p as a biomarker of clear cell renal cell carcinoma that inhibits progression by targeting HSPA5

Exosome-derived miRNAs are regarded as biomarkers for the diagnosis and prognosis of many human cancers. However, its function in clear cell renal cell carcinoma (ccRCC) remains unclear. In this study, differentially expressed miRNAs from urinal exosomes were identified using next-generation sequencing (NGS) and verified using urine samples of ccRCC patients and healthy donors. Then, the exosomes were analysed in early-stage ccRCC patients, healthy individuals and patients suffering from other urinary system cancers. Thereafter, the target gene of the miRNA was detected. Its biological function was investigated in vitro and in vivo. The results showed that miR-30c-5p could be amplified in a stable manner. Its expression pattern was significantly different only between ccRCC patients and healthy control individuals, but not compared with that of other urinary system cancers, which indicated its specificity for ccRCC. Additionally, the overexpression of miR-30c-5p inhibited ccRCC progression in vitro and in vivo. Heat-shock protein 5 (HSPA5) was found to be a direct target gene of miR-30c-5p. The depletion of HSPA5 caused by miR-30c-5p inhibition reversed the promoting effect of ccRCC growth. In conclusion, urinary exosomal miR-30c-5p acts as a potential diagnostic biomarker of early-stage ccRCC and may be able to modulate the expression of HSPA5, which is correlated with the progression of ccRCC.

The deubiquitylase OTUD3 stabilizes GRP78 and promotes lung tumorigenesis

The deubiquitylase OTUD3 plays a suppressive role in breast tumorigenesis through stabilizing PTEN protein, but its role in lung cancer remains unclear. Here, we demonstrate that in vivo deletion of OTUD3 indeed promotes breast cancer development in mice, but by contrast, it slows down Kras^G12D-driven lung adenocarcinoma (ADC) initiation and progression and markedly increases survival in mice. Moreover, OTUD3 is highly expressed in human lung cancer tissues and its higher expression correlates with poorer survival of patients. Further mechanistic studies reveal that OTUD3 interacts with, deubiquitylates and stabilizes the glucose-regulated protein GRP78. Knockdown of OTUD3 results in a decrease in the level of GRP78 protein, suppression of cell growth and migration, and tumorigenesis in lung cancer. Collectively, our results reveal a previously unappreciated pro-oncogenic role of OTUD3 in lung cancer and indicate that deubiquitylases could elicit tumor-suppressing or tumor-promoting activities in a cell- and tissue-dependent context.

The deubiquitylase OTUD3 can function as a tumour-suppressor by stabilizing PTEN. Here, the authors show that OTUD3 also has an oncogenic role in lung cancer by stabilizing the glucose-regulated protein GRP78.

Impact and Relevance of the Unfolded Protein Response in HNSCC

Head and neck squamous cell carcinomas (HNSCC) encompass a heterogeneous group of solid tumors that arise from the upper aerodigestive tract. The tumor cells face multiple challenges including an acute demand of protein synthesis often driven by oncogene activation, limited nutrient and oxygen supply and exposure to chemo/radiotherapy, which forces them to develop adaptive mechanisms such as the Unfolded Protein Response (UPR). It is now well documented that the UPR, a homeostatic mechanism, is induced at different stages of cancer progression in response to intrinsic (oncogenic activation) or extrinsic (microenvironment) perturbations. This review will discuss the role of the UPR in HNSCC as well as in the key processes that characterize the physiology of HNSCC. The role of the UPR in the clinical context of HNSCC will also be addressed.

GRP78-targeted ferritin nanocaged ultra-high dose of doxorubicin for hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) remains one of the leading causes of cancer deaths, primarily due to its high incidence of recurrence and metastasis. Considerable efforts have therefore been undertaken to develop effective therapies; however, effective anti-HCC therapies rely on identification of suitable biomarkers, few of which are currently available for drug targeting.

Methods: GRP78 was identified as the membrane receptor of HCC-targeted peptide SP94 by immunoprecipitation and mass spectrum analysis. To develop an effective anti-HCC drug nanocarrier, we first displayed GRP78-targeted peptide SP94 onto the exterior surface of Pyrococcus furiosus ferritin Fn (HccFn) by genetic engineering approach, and then loaded doxorubicin (Dox) into the cavities of HccFn via urea-based disassembly/reassembly method, thereby constructing a drug nanocarrier called HccFn-Dox.

Results: We demonstrated that HccFn nanocage encapsulated ultra-high dose of Dox (up to 400 molecules Dox/protein nanocage). In vivo animal experiments showed that Dox encapsulated in HccFn-Dox was selectively delivered into HCC tumor cells, and effectively killed subcutaneous and lung metastatic HCC tumors. In addition, HccFn-Dox significantly reduced drug exposure to healthy organs and improved the maximum tolerated dose by six-fold compared with free Dox.

Conclusion: In conclusion, our findings clearly demonstrate that GRP78 is an effective biomarker for HCC therapy, and GRP78-targeted HccFn nanocage is effective in delivering anti-HCC drug without damage to healthy tissue.

Glucose-Regulated Protein 78 Signaling Regulates Hypoxia-Induced Epithelial-Mesenchymal Transition in A549 Cells

Objective: Metastasis and therapeutic resistance are the major determinants of lung cancer progression and high mortality. Epithelial-mesenchymal transition (EMT) plays a key role in the metastasis and therapeutic resistance. Highly expressed glucose-regulated protein 78 (GRP78) is a poor prognostic factor in lung cancer and possibly correlated with EMT. This study aims to examine whether the up-regulation of GRP78 is involved in EMT in lung adenocarcinoma and explore the underlying downstream molecular pathways. Study Design: EMT was assessed by analysis of cell morphology and expression of EMT protein markers in A549 cells under normoxia, hypoxia and silencing GRP78 conditions. The expression levels of Smad2/3, Src, and MAPK (p38, ERK, and JNK) proteins were examined by Western blot analysis under hypoxia and treatments with phosphorylation inhibitors. Results: Under hypoxic conditions, the EMT morphology significantly changed and the GRP78 expression was significantly up-regulated in A549 cells compared with those in normoxia control. The expression and phosphorylation levels of smad2/3, Src, p38, ERK, and JNK were also upregulated. When GRP78 was silenced, EMT was inhibited, and the levels of phospho-smad2/3, phospho-Src, phospho-p38, phospho-ERK, and phospho-JNK were suppressed. When the activation of Smad2/3, Src, p38, ERK, and JNK was inhibited, EMT was also inhibited. The inhibition effect on EMT by these phosphorylation inhibitors was found to be weaker than that of GRP78 knockdown. Conclusions: Hypoxia-induced EMT in A549 cells is regulated by GRP78 signaling pathways. GRP78 promotes EMT by activating Smad2/3 and Src/MAPK pathways. Hence, GRP78 might be a potential target for treatment of lung adenocarcinoma.

Tunicamycin-induced ER stress in breast cancer cells neither expresses GRP78 on the surface nor secretes it into the media

GRP78 (an Mr 78 kDa calcium dependent glucose binding protein) is located in ER lumen. It functions as ER chaperone and translocates proteins for glycosylation at the asparagine residue present in the sequon Asn-X-Ser/Thr. Paraffin sections from N-glycosylation inhibitor tunicamycin treated ER-/PR-/HER2+ (double negative) breast tumor in athymic nude mice exhibited reduced N-glycan but increased GRP78 expression. We have evaluated the effect of tunicamycin on cellular localization of GRP78 in metastatic human breast cancer cells MDA-MB-231 (ER-/PR-/HER2-). Tunicamycin inhibited cell proliferation in a time and dose-dependent manner. Nonmetastatic estrogen receptor positive (ER+) MCF-7 breast cancer cells were also equally effective. GRP78 expression (protein and mRNA) was higher in tunicamycin (1.0 μg/mL) treated MCF-7 and MDA-MB-231 cells. GRP78 is an ER stress marker, so we have followed its intracellular localization using immunofluorescence microscopy after subjecting the cancer cells to various stress conditions. Unfixed cells stained with either FITC-conjugated Concanavalin A (Con A) or Texas-red conjugated wheat germ agglutinin (WGA) exhibited surface expression of N-glycans but not GRP78. GRP78 became detectable only after a brief exposure of cells to ice-cold methanol. Western blotting did not detect GRP78 in conditioned media of cancer cells whereas it did for MMP-1. The conclusion, GRP78 is expressed neither on the outer-leaflet of the (ER-/PR-/HER2-) human breast cancer cells nor it is secreted into the culture media during tunicamycin-induced ER stress. Our study therefore suggests strongly that anti-tumorigenic action of tunicamycin can be modeled to develop next generation cancer therapy, i.e., glycotherapy for treating breast and other sold tumors.

Obesity Drives STAT-1-Dependent NASH and STAT-3-Dependent HCC

Obesity is a major driver of cancer, especially hepatocellular carcinoma (HCC). The prevailing view is that non-alcoholic steatohepatitis (NASH) and fibrosis or cirrhosis are required for HCC in obesity. Here, we report that NASH and fibrosis and HCC in obesity can be dissociated. We show that the oxidative hepatic environment in obesity inactivates the STAT-1 and STAT-3 phosphatase T cell protein tyrosine phosphatase (TCPTP) and increases STAT-1 and STAT-3 signaling. TCPTP deletion in hepatocytes promoted T cell recruitment and ensuing NASH and fibrosis as well as HCC in obese C57BL/6 mice that normally do not develop NASH and fibrosis or HCC. Attenuating the enhanced STAT-1 signaling prevented T cell recruitment and NASH and fibrosis but did not prevent HCC. By contrast, correcting STAT-3 signaling prevented HCC without affecting NASH and fibrosis. TCPTP-deletion in hepatocytes also markedly accelerated HCC in mice treated with a chemical carcinogen that promotes HCC without NASH and fibrosis. Our studies reveal how obesity-associated hepatic oxidative stress can independently contribute to the pathogenesis of NASH, fibrosis, and HCC.

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Obesity promotes hepatic STAT-1 and STAT-3 signaling

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Obesity promotes STAT-1-dependent T cell-infiltration, NASH, and fibrosis

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Obesity promotes NASH-independent STAT-3-dependent HCC

Inhibition of endoplasmic-reticulum-stress-mediated autophagy enhances the effectiveness of chemotherapeutics on pancreatic cancer

Background

Endoplasmic reticulum (ER) stress and its consequent unfolded protein response (UPR) are believed to be associated with progression, survival and chemoresistance of a variety of tumor cells through multiple cellular processes, including autophagy. Therefore, the ER stress-autophagy pathway presents a potential molecular target for therapeutic intervention. The objective of this study was to evaluate the therapeutic efficacy of ER stress and autophagy modulators in the context of pancreatic ductal adenocarcinoma (PDAC).

Methods

We first targeted IRE1α, an important regulator of the UPR, through STF-083010 treatment in PDAC cell lines in vitro. Chloroquine was then used to target autophagy and an optimal combination treatment was developed using chloroquine, sunitinib and gemcitabine. Apoptosis was analyzed using TUNEL assay, autophagy was estimated using lysotracker staining and electron microscopy, and UPR was analyzed using anti-GRP78 immunostaining and XBP1 splicing. Transplantation of PDAC derived KPCP1 and Panc02 cells in mouse pancreas were performed to study treatment efficacy in vivo.

Results

Suppression of the IRE1α by STF-083010 alone resulted in increased lysosomes and reduced viability of PDAC cells. Chloroquine treatment alone inhibited downstream autophagy but was insufficient in reducing PDAC cell growth. However, combining STF-083010 and chloroquine had additive anti-tumor efficacy when used with gemcitabine. Sunitinib alone caused abnormal maturation of the autolysosomes with increased intracellular multivesicular bodies and increased apoptosis evident in PDAC cells. Sunitinib showed a synergistic effect with chloroquine in reducing in vitro PDAC cell viability and significantly increased the efficacy of gemcitabine in human and murine PDAC cell lines. The anti-proliferative effect of gemcitabine was significantly increased when used in combination with sunitinib and/or chloroquine in both in vitro and in vivo PDAC models. The addition of sunitinib and/or chloroquine to gemcitabine, resulted in a significantly increased survival of the animals without noticeably increased toxicity. Sunitinib, gemcitabine and chloroquine treated mice showed a significant reduction of GRP78 expression, reduced cell proliferation and increased apoptosis in pancreas, compatible with a tumor response.

Conclusions

Sunitinib combined with chloroquine reduces tumor growth through suppression of autophagy and increased apoptosis. Co-administration of modulators of ER stress-mediated autophagy with chemotherapy presents a novel therapeutic approach in PDAC.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1562-z) contains supplementary material, which is available to authorized users.

Mouse models for investigating the underlying mechanisms of nonalcoholic steatohepatitis-derived hepatocellular carcinoma

As the incidence of hepatocellular carcinoma (HCC) caused by infection with the hepatotropic viruses hepatitis B and hepatitis C decreases, greater attention has become focused on HCC caused by nonalcoholic steatohepatitis (NASH), an advanced form of nonalcoholic fatty liver disease which has shown increasing prevalence in correspondence with the overall increase in metabolic syndrome over the recent decades. Several clinical population studies have shown a positive relationship between NASH and HCC, while also providing initial insights into the underlying mechanisms of HCC development from NASH. Research into the pathological progression of NASH to HCC has advanced by use of several beneficial rodent models. In this review, we summarize the established mouse models for preclinical research of NASH-associated HCC and discuss the underlying hepatic mechanisms of NASH-related tumorigenesis identified to date that could lead to new targets for treatment and prevention.

Deficiency of protein-L-isoaspartate (D-aspartate) O-methyl-transferase expression under endoplasmic reticulum stress promotes epithelial mesenchymal transition in lung adenocarcinoma

A prognostic association between the novel chaperone protein-L-isoaspartate (D-aspartate) O-methyltransferase (PIMT) and lung adenocarcinoma has recently been reported. Here, we evaluated the functional roles of PIMT in the progression of lung adenocarcinoma. PIMT expression was detectable in 6 lung adenocarcinoma cell lines: A549, H441, H460, H1650, Calu 1, and Calu 6 cell lines. In A549 and H441 cells, knockdown by PIMT using silencing RNA of PIMT (si-PIMT) and/or small hairpin-RNA (sh-PIMT) induced a decrease in the expression of E-cadherin with an increase in vimentin expression, indicating that the epithelial to mesenchymal transition (EMT) was induced. Cell mobility, including migration and invasion capability, was increased in sh-PIMT A549 stable and si-PIMT H441 cells compared to in control cells. Endoplasmic reticulum (ER) stress, such as Thapsigargin (Tg) stress and hypoxia, induced EMT in A549 cells but not in other cell types, with an increase in GRP78 expression, whereas overexpression of PIMT reduced the EMT and cell invasion under stress conditions. The expression of hypoxia inducible factor-1 alpha (HIF1α) and Twist increased in sh-PIMT A549 and si-PIMT H441 cells, and Tg stress increased HIF1α expression levels in A549 cells in a dose-dependent manner. Moreover, LW6, an HIF1α inhibitor, reduced EMT, cancer invasion, and the levels of Twist in sh-PIMT A549 cells. Our results indicate that deficiency of supplemental PIMT expression under ER stress facilitates EMT and cell invasion in some cell types of lung adenocarcinoma.

Oncolytic vaccinia virus inhibits human hepatocellular carcinoma MHCC97-H cell proliferation via endoplasmic reticulum stress, autophagy and Wnt pathways

BACKGROUND

Hepatocellular carcinoma (HCC) is a highly lethal malignancy. Vaccinia virus (VV) possessed many inherent advantages with respect to being engineered as a vector for cancer gene therapy, although the mechanism of action remains to be explored further.

METHODS

We constructed a thymidine kinase gene insertional inactivated VV, named VV-Onco, and then tested its effects on cell viability, apoptosis and colony formation ability in a highly metastatic human hepatocellular carcinoma cell line MHCC97-H, and also investigated the potential cell signal pathways involved in this action.

RESULTS

VV-Onco induced strong cytotoxicity and apoptosis and also inhibited the colony formation of MHCC97-H cells. The tumor cell apoptosis induced by VV-Onco is likely mediated via endoplasmic reticulum stress, autophagy and Wnt signaling pathways. The downregulation of survivin and c-Myc may also play a role in VV-Onco induced cell death.

CONCLUSIONS

The results of the present study provide new insights into the mechanisms of VV-induced tumor cell death. The engineered recombinant VV containing optimized therapeutic transgenes may represent a new avenue for cancer gene therapy. Copyright © 2016 John Wiley & Sons, Ltd.

GRP78 overexpression as an unfavorable outcome in glioma patients

AIMS

In this study, the GRP78 expression and the correlation between GRP78 expression and clinicopathologic data in patients with glioma, including survival, were examined.

METHODS AND RESULTS

The mRNA and protein levels of GRP78were respectively determined by real-time PCR and immunohistochemical analysis in 30 fresh glioma samples and 19 fresh normal brain samples as well as 156 paraffin-embedded glioma samples and 35 normal paraffin-embedded brain samples. The data showed that GRP78 mRNA is markedly upregulated compared with normal brain tissues. Consistent with this data, the GRP78 protein level was also significantly increased in glioma tissues compared with normal brain tissues. We further observed that high GRP78 protein expression was significantly associated with clinical stage (P = 0.0013) but did not correlate with age and gender. High, rather than low, GRP78 protein expression was associated with pooroverall survival rates (P = 0.001). Multivariate analysis indicated that high GRP78 protein expression was an independent prognostic indicator of patient survival (P = 0.002).

CONCLUSIONS

Our findings demonstrate that GRP78 is overexpressed and plays a significant role in disease progression and poor outcome in patients with glioma.

Secreted GRP78 activates EGFR-SRC-STAT3 signaling and confers the resistance to sorafeinib in HCC cells

Acquired resistance is a common phenomenon for HCC patients who undergone sorafenib treatment, however the mechanism by which acquired resistance develops remains elusive. In this study, we found that GRP78 could be detected in the serum samples of HCC patients and the conditional medium of multiple HCC cell lines, suggesting that GRP78 is secreted by HCC cells. Further studies showed that secreted GRP78 facilitated the proliferation and inhibited the apoptosis induced by sorafenib both in HCC cell lines and in tumor xenografts. We further found that secreted GRP78 could interact physically with EGFR, therefore activates EGFR signaling pathway. knockdown of EGFR decreased secreted GRP78 induced phosphorylation of SRC and STAT3. By contrast, overexpression of EGFR further enhanced the phosphorylation of SRC and STAT3 induced by secreted GRP78, suggesting the critical role of EGFR in secreted GRP78 conferred resistance to sorafeinib. Moreover, inhibition of SRC by PP2 antagonized the resistance to sorafenib and inhibited the activation of STAT3 conferred by secreted GRP78. Taken together, our results showed that secreted GRP78 could interact with EGFR, activate EGFR-SRC-STAT3 signaling, conferring the resistance to sorafenib.

Granulin-epithelin precursor interacts with 78-kDa glucose-regulated protein in hepatocellular carcinoma

Background

Granulin-epithelin precursor (GEP) is a secretory growth factor, which has been demonstrated to control cancer growth, invasion, drug resistance and immune escape. Our previous studies and others also demonstrated its potential in targeted therapy. Comprehensive characterization of GEP partner on cancer cells are warranted. We have previously shown that GEP interacted with heparan sulfate on the surface of liver cancer cells and the interaction is crucial for GEP-mediated signaling transduction. This study aims to characterize GEP protein partner at the cell membrane with the co-immunoprecipitation and mass spectrometry approach.

Methods

The membrane fraction from liver cancer model Hep3B was used for capturing binding partner with the specific monoclonal antibody against GEP. The precipitated proteins were analyzed by mass spectrometry. After identifying the GEP binding partner, this specific interaction was validated in additional liver cancer cell line HepG2 by co-immunoprecipitation using GRP78 and GEP antibodies, respectively, as the bait. GRP78 transcript levels in hepatocellular carcinoma (HCC) clinical samples (n = 77 pairs) were examined by real-time quantitative RT-PCR. GEP and GRP78 protein expressions were investigated by immunohistochemistry on paraffin sections.

Results

We identified the GEP-binding protein as 78-kDa glucose-regulated protein (GRP78, also named heat shock 70-kDa protein 5, HSPA5). This interaction was validated in independent HCC cell lines. Increased GRP78 mRNA levels were demonstrated in liver cancer tissues compared with the paralleled liver tissues (t-test, P = 0.002). GRP78 and GEP transcript levels were significantly correlated (Spearman’s correlation, P = 0.001), and the proteins were also detectable in the cytoplasm of liver cancer cells by immunohistochemical staining.

Conclusions

GRP78 and GEP are interacting protein partners in liver cancer cells and may play a role in GEP-mediated cancer progression in HCC.

Glucose-regulated protein 78 demonstrates antiviral effects but is more suitable for hepatocellular carcinoma prevention in hepatitis B

Background

Hepatitis B virus (HBV) is the leading cause of liver cirrhosis and hepatocellular carcinoma in Asia and Africa. Existing antivirals cannot cure HBV or eliminate risk of hepatocellular carcinoma. Glucose-regulated protein 78 (GRP78) can inhibit HBV replication, but promote virion secretion and hepatocellular cancer cell invasion. For these reasons, the overall effect of GRP78 on HBV production and whether to utilize the HBV replication-inhibitory effect of GRP78 up-regulation or the hepatocellular cancer cell invasion-inhibitory effect of its down-regulation were further investigated in order to improve the efficacy of current antiviral therapy.

Methods

GRP78 regulations in HepG2.2.15 cells were conducted by transfections of expressing vector and small interfering RNA, respectively. The changes in HBV replication, hepatitis B e antigen (HBeAg) synthesis and hepatoma cell motility were monitored.

Results

GRP78 overall decreased HBV production due to its HBV replication-inhibitory effect time-dependently overwhelming virion secretion-promoting effect in HepG2.2.15 cells. Unlike the parental cells (HepG2), HepG2.2.15 cells demonstrated decreased expressions of the major genes in the interferon-β1-dependent pathway. Moreover, the expressions of these genes were not affected by GRP78 regulations. However, GRP78 was found to inhibit HBeAg secretion and to increase the retro-transportation of capsid assembly-interfering HBeAg precursor from the endoplasmic reticulum into the cytosol where new viral nucleocapsids formed. Furthermore, GRP78 overexpression promoted wound healing process (the motility) of HepG2.2.15 cells. In contrast, GRP78 knockdown enhanced HBV replication and HBeAg secretion, but they were abolished by entecavir and furin inhibitor, respectively.

Conclusions

GRP78 mainly demonstrates anti-HBV effects, reducing HBV production and HBeAg secretion. With due regard to the hepatocellular cancer invasion risk of the overexpression and the rectifiability of the unpleasant effects of the knockdown, GRP78 down-regulation may be more suitable to serve as an additive strategy to cover the hepatocellular cancer prevention shortage of current antiviral therapy in the future.

Antitumor agent 25-epi Ritterostatin GN1N induces endoplasmic reticulum stress and autophagy mediated cell death in melanoma cells

Metastatic melanoma is the most aggressive of all skin cancers and is associated with poor prognosis owing to lack of effective treatments. 25-epi Ritterostatin G_N1_N is a novel antitumor agent with yet undefined mechanisms of action. We sought to delineate the antitumor mechanisms of 25-epi Ritterostatin G_N1_N in melanoma cells to determine the potential of this compound as a treatment for melanoma. Activation of the endoplasmic reticulum (ER) stress protein glucose-regulated protein 78 (GRP78) has been associated with increased melanoma progression, oncogenic signaling, drug resistance, and suppression of cell death. We found that 25-epi Ritterostatin G_N1_N induced cell death in melanoma cells at nanomolar concentrations, and this cell death was characterized by inhibition of GRP78 expression, increased expression of the ER stress marker CHOP, loss of mitochondrial membrane potential, and lipidation of the autophagy marker protein LC3B. Importantly, normal melanocytes exhibited limited sensitivity to 25-epi Ritterostatin G_N1_N. Subsequent in vivo results demonstrated that 25-epi Ritterostatin G_N1_N reduced melanoma growth in mouse tumor xenografts and did not affect body weight, suggesting minimal toxicity. In summary, our findings indicate that 25-epi Ritterostatin G_N1_N causes ER stress and massive autophagy, leading to collapse of mitochondrial membrane potential and cell death in melanoma cells, with minimal effects in normal melanocytes. Thus, 25-epi Ritterostatin G_N1_N is a promising anticancer agent that warrants further investigation.

High expression of glucose-regulated protein 78 (GRP78) is associated with metastasis and poor prognosis in patients with esophageal squamous cell carcinoma

Background

Glucose-regulated protein 78 (GRP78) plays an important role in the invasion and metastasis of many human cancers. However, the role of this protein in the progression of invasion and metastasis in esophageal squamous cell carcinoma (ESCC) remains elusive.

Patients and methods

Immunohistochemistry and Western blot were performed to analyze GRP78 expression in 92 patients with primary ESCC. The correlation of GRP78 expression with clinicopathological factors was analyzed. In vitro, the expression levels of GRP78 were downregulated by small interfering RNA transfection in TE-1 and CaEs-17 ESCC lines. Cell invasion and migration assays were applied to determine the invasion and migratory abilities of ESCC cells.

Results

Compared with GRP78 in adjacent normal esophageal tissues, GRP78 was overexpressed in ESCC tissues. High GRP78 expression was significantly correlated with positive lymph node metastasis (P=0.035) and advanced tumor stage (P=0.017). Survival analysis revealed that high GRP78 expression was significantly associated with shorter overall survival (P=0.037). In multivariate analysis, GRP78 overexpression was identified as an independent prognostic factor for overall survival (P=0.011). si-GRP78 can significantly decrease the GRP78 expression level and reverse the invasion and migratory abilities of ESCC cells in TE-1 and CaEs-17 cell lines.

Conclusion

These findings demonstrated that high expression of GRP78 was associated with disease progression and metastasis in ESCC and might serve as a novel prognostic marker for patients with ESCC.

High Level Soluble Expression and ATPase Characterization of Human Heat Shock Protein GRP78

Human GRP78 has been shown to promote cancer progression and is regarded as a novel target for anticancer drugs. However, generation of recombinant full-length GRP78 remains challenging. This report demonstrates that E. coli autoinduction is an excellent method for the preparation of active recombinant GRP78 protein. The final yield was approximately 50 mg/liter of autoinduction culture. Gel-filtration experiments confirmed that the chaperone is a monomer. The purified human GRP78 catalyzed the conversion of ATP to ADP without requiring metal ions as cofactors. Three mutants, T38A, T229A, and S300A, exhibited much lower activity than wild-type GRP78, indicating that the active sites of the ATPase are located at the negatively charged cavity. Three mutants in the negatively charged cavity region dramatically reduced GRP78 activity, further confirming the region as the site of ATPase activity.

GRP78 confers the resistance to 5-FU by activating the c-Src/LSF/TS axis in hepatocellular carcinoma

5-FU is a common first-line chemotherapeutic drug for the treatment of hepatocellular carcinoma. However the development of acquired resistance to 5-FU confines its clinical usages. Although this phenomenon has been the subject of intense investigation, the exact mechanism of acquired resistance to 5-FU remains elusive. Here, we report that over-expression of GRP78 contributes to acquired resistance to 5-FU in HCC by up-regulating the c-Src/LSF/TS axis. Moreover, we found that the resistance to 5-FU conferred by GRP78 is mediated by its ATPase domain. The ATPase domain differentially increased the expression of LSF, TS and promoted the phosphorylation of ERK and Akt. We further identified that GRP78 interacts physically with c-Src through its ATPase domain and promotes the phosphorylation of c-Src, which in turn increases the expression of LSF in the nucleus. Together, GRP78 confers the resistance to 5-FU by up-regulating the c-Src/LSF/TS axis via its ATPase domain.

3'3-Diindolylmethane inhibits migration, invasion and metastasis of hepatocellular carcinoma by suppressing FAK signaling

Late stage hepatocellular carcinoma (HCC) usually has a low survival rate because it has high potential of metastases and there is no effective cure. 3'3-Diindolylmethane (DIM) is the major product of the acid-catalyzed oligomerization of indole-3-carbinol present in cruciferous vegetables. DIM has been proved to exhibit anticancer properties. In this study, we explored the effects and molecular mechanisms of anti-metastasis of DIM on HCC cells both in vitro and in vivo. We chose two HCC cell lines SMMC-7721 and MHCC-97H that have high potential of invasion. The results showed that DIM inhibited the proliferation, migration and invasion of these two cell lines in vitro. In addition, in vivo study demonstrated that DIM significantly decreased the volumes of SMMC-7721 orthotopic liver tumor and suppressed lung metastasis in nude mice. Focal Adhesion Kinase (FAK) is found over activated in HCC cells. We found that DIM decreased the level of phospho-FAK (Tyr397) both in vitro and in vivo. DIM inhibition of phospho-FAK (Tyr397) led to down-regulation of MMP2/9 and decreased potential of metastasis. DIM also repressed the migration and invasion induced by vitronectin through inactivation of FAK pathway and down-regulation of MMP2/9 in vitro. We also found that pTEN plays a role in down-regulation of FAK by DIM. These results demonstrated that DIM blocks HCC cell metastasis by suppressing tumor cell migration and invasion. The anti-metastasis effect of DIM could be explained to be its down-regulated expression and activation of MMP2/9 partly induced by up-regulation of pTEN and inhibition of phospho-FAK (Tyr397).

Expression of GRP78, Master Regulator of the Unfolded Protein Response, Increases Chemoresistance in Pancreatic Ductal Adenocarcinoma

The prognosis for patients with pancreatic ductal adenocarcinoma (PDAC) is dismal. Although gemcitabine (GEM) is the standard chemotherapeutic agent for adjuvant therapy of resectable PDAC, recurrent disease is observed in an alarming number of GEM-treated patients. Regardless of the adjuvant therapy, the vast majority of patients treated with chemotherapy after surgical resection show tumor recurrence. A better understanding of the molecular mechanisms that contribute to chemoresistance would aid the development of more effective treatment strategies. GRP78 is an endoplasmic reticulum (ER) chaperone protein that primarily resides in the lumen of the ER and is the master regulator of the unfolded protein response (UPR). Here, we report that expression of GRP78 is significantly higher in GEM-resistant PDAC compared to GEM-sensitive PDAC patient samples. We show that GRP78 induces chemoresistance in PDAC cells. Our results also show that knockdown of GRP78 reduces chemoresistance in PDAC. Finally, we found that IT-139, a ruthenium-based anticancer drug, can overcome GRP78-mediated chemoresistance. In vitro, IT-139 restores sensitivity to cytotoxic drugs in drug-resistant PDAC cells and induces twice as much cell death in combination treatment compared with GEM alone. In vivo, a single weekly IT-139 treatment in combination with GEM caused a 35% increase in median survival and a 25% increase in overall survival compared to GEM alone. Collectively, our data show that GRP78 expression promotes chemoresistance in PDAC and therapeutic strategies, blocking the activity of GRP78 increases the efficacy of currently available therapies. Mol Cancer Ther; 15(5); 1043-52. ©2016 AACR.

Melanoma and the Unfolded Protein Response

The UPR (unfolded protein response) has been identified as a key factor in the progression and metastasis of cancers, notably melanoma. Several mediators of the UPR are upregulated in cancers, e.g., high levels of GRP78 (glucose-regulator protein 78 kDa) correlate with progression and poor outcome in melanoma patients. The proliferative burden of cancer induces stress and activates several cellular stress responses. The UPR is a tightly orchestrated stress response that is activated upon the accumulation of unfolded proteins within the ER (endoplasmic reticulum). The UPR is designed to mediate two conflicting outcomtes, recovery and apoptosis. As a result, the UPR initiates a widespread signaling cascade to return the cell to homeostasis and failing to achieve cellular recovery, initiates UPR-induced apoptosis. There is evidence that ER stress and subsequently the UPR promote tumourigenesis and metastasis. The complete role of the UPR has yet to be defined. Understanding how the UPR allows for adaption to stress and thereby assists in cancer progression is important in defining an archetype of melanoma pathology. In addition, elucidation of the mechanisms of the UPR may lead to development of effective treatments of metastatic melanoma.

Involvement of GRP78 in the Resistance of Ovarian Carcinoma Cells to Paclitaxel

BACKGROUND

Glucose regulated protein 78 (GRP78) is a type of molecular chaperone. It is a possible candidate protein that contributes to development of drug resistance. We first examined the involvement of GRP78 in chemotherapy-resistance in human ovarian cancer cell.

MATERIALS AND METHODS

The expression of GRP78 mRNA and protein were examined by RT-PCR and western blotting, respectively, in human ovarian cancer cells line (HO-8910). Sensitivity of HO-8910 to paclitaxel was determined with methyl thiazolyl tetrazolium (MTT). Suppression of GRP78 expression was performed using specific small-interfering RNA (siRNA) in HO-8910 cells, and cell apoptosis was assessed by flow cytometry. Statistical analysis was performed using the SPSS 15.0 statistical package.

RESULTS

HO-8910 cells, with high basal levels of GRP78, exhibited low sensitivity to paclitaxel. The mRNA and protein levels of GRP78 were dramatically decreased at 24h, 48h and 72h after transfection and the sensitivity to paclitaxel was increased when the GRP78 gene was disturbed by specific siRNA transfection.

CONCLUSIONS

The results suggested that high GRP78 expression might be one of the molecular mechanisms causing resistance to paclitaxel, and therefore siRNA of GRP78 may be useful in tumor-specific gene therapy for ovarian cancer.

Melatonin Activates Endoplasmic Reticulum Stress and Apoptosis in Rats with Diethylnitrosamine-Induced Hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is one of the most lethal human cancers worldwide because of its high incidence, its metastatic potential and the low efficacy of conventional treatment. Inactivation of apoptosis is implicated in tumour progression and chemotherapy resistance, and has been linked to the presence of endoplasmic reticulum stress. Melatonin, the main product of the pineal gland, exerts anti-proliferative, pro-apoptotic and anti-angiogenic effects in HCC cells, but these effects still need to be confirmed in animal models. Male Wistar rats in treatment groups received diethylnitrosamine (DEN) 50 mg/kg intraperitoneally twice/once a week for 18 weeks. Melatonin was given in drinking water at 1 mg/kg/d, beginning 5 or 12 weeks after the start of DEN administration. Melatonin improved survival rates and successfully attenuated liver injury, as shown by histopathology, decreased levels of serum transaminases and reduced expression of placental glutathione S-transferase. Furthermore, melatonin treatment resulted in a significant increase of caspase 3, 8 and 9 activities, polyadenosine diphosphate (ADP) ribose polymerase (PARP) cleavage, and Bcl-associated X protein (Bax)/Bcl-2 ratio. Cytochrome c, p53 and Fas-L protein concentration were also significantly enhanced by melatonin. Melatonin induced an increased expression of activating transcription factor 6 (ATF6), C/EBP-homologous protein (CHOP) and immunoglobulin heavy chain-binding protein (BiP), while cyclooxygenase (COX)-2 expression decreased. Data obtained suggest that induction of apoptosis and ER stress contribute to the beneficial effects of melatonin in rats with DEN-induced HCC.

Elevated GRP78 expression is associated with poor prognosis in patients with pancreatic cancer

Glucose-regulated protein 78 (GRP78) is a member of the heat-shock protein 70 family. We evaluated the expression of GRP78 using tissue microarray-based immunohistochemistry in tumor tissues and adjacent nontumor tissues from 180 pancreatic ductal adenocarcinoma (PDAC) patients. The associations between the expression levels of GRP78, clinicopathological factors, and overall survival were evaluated. The results showed that the expression of GRP78 was significantly higher in PDAC cells than in normal pancreatic duct cells within adjacent nontumor tissues (p < 0.05). The increased expression of GRP78 in the tumor tissues was significantly correlated with a higher T-stage (p < 0.05) and a shorter overall survival (OS, p < 0.05). In an in vitro study, the regulation of GRP78 in the PDAC cell lines affected the proliferation, migration, and invasion of PDAC cells through the regulation of CyclinD1, cyclin-dependent kinase (CDK) 4, CDK6, phospho-signal transducer, activator of transcription 3 (p-STAT3), janus kinase 2 (JAK2), ras homolog gene family member A (RhoA), Rho-associated kinase 1 (ROCK1), and sterile alpha motif domain containing protein 4 (Smad4). The present data suggest that GRP78 plays a crucial role in the proliferation, migration, and invasion of pancreatic cancer cells and may be a suitable prognostic marker in PDAC.

High Expression of GRP78 Promotes Invasion and Metastases in Patients with Esophageal Squamous Cell Carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) has a poor prognosis due to its high frequency of metastasis and invasion. Recent studies have suggested glucose-regulated protein 78KD (GRP78) may play important roles in progression and development of malignant tumors. However, the mechanisms of invasion and metastasis of ESCC in relation to GRP78 still remain obscure.

AIM

The aim of this study was to investigate the effect of GRP78 on invasion and metastasis of ESCC and to explore its potential mechanism.

METHODS

GRP78 expression levels in ESCC tissues were examined by immunohistochemistry. RT-PCR and western blot were used to test the relative expression of GRP78 in non-metastatic and high-metastatic ESCC cells. In vitro and in vivo studies were both performed to investigate the role of GRP78 in invasion and metastasis of ESCC cells. The expression of metastasis-related proteins was examined by western blot in GRP78-depleted cells.

RESULTS

The expression of GRP78 is correlated with invasion, metastasis and poor prognosis in ESCC patients. GRP78 expression was significantly higher in highly metastatic cells compared with ESCC non-metastatic cells. In addition, down-regulation of GRP78 significantly inhibited the metastatic potential of ESCC cells in both in vitro and in vivo studies. The expression of MMP-2 and MMP-9 were down-regulated in GRP78-depleted ESCC cells.

CONCLUSIONS

The present study demonstrated that GRP78 plays important roles in invasion and metastasis of ESCC, indicating that GRP78 might be used as a potential prognostic and therapeutic marker in patients with ESCC by modulating the expression of MMP-2 and MMP-9.

De-acetylation and degradation of HSPA5 is critical for E1A metastasis suppression in breast cancer cells

Elevated expression of heat shock protein 5 (HSPA5) promotes drug resistance and metastasis and is a marker of poor prognosis in breast cancer patients. Adenovirus type 5 E1A gene therapy has demonstrated antitumor efficacy but the mechanisms of metastasis-inhibition are unclear. Here, we report that E1A interacts with p300 histone acetyltransferase (HAT) and blocks p300-mediated HSPA5 acetylation at K353, which in turn promotes HSPA5 ubiquitination by GP78 (E3 ubiquitin ligase) and subsequent proteasome-mediated degradation. Our findings point out the Ying-Yang regulation of two different post-translational modifications (ubiquitination and acetylation) of HSPA5 in tumor metastasis.

Unfolding the Role of Stress Response Signaling in Endocrine Resistant Breast Cancers

The unfolded protein response (UPR) is an ancient stress response that enables a cell to manage the energetic stress that accompanies protein folding. There has been a significant recent increase in our understanding of the UPR, how it integrates physiological processes within cells, and how this integration can affect cancer cells and cell fate decisions. Recent publications have highlighted the role of UPR signaling components on mediating various cell survival pathways, cellular metabolism and bioenergenics, and autophagy. We address the role of UPR on mediating endocrine therapy resistance and estrogen receptor-positive breast cancer cell survival.

Glucose regulated protein 78 promotes cell invasion via regulation of uPA production and secretion in colon cancer cells

Glucose regulated protein 78 (GRP78) is frequently highly expressed in tumor cells, contributing to the acquisition of several phenotypic cancer hallmarks. GRP78 expression is also positively correlated with tumor metastasis, and promotes hepatocellular carcinoma cell invasion via increasing cell motility, however, other mechanisms involving the prometastatic roles of GRP78 remain to be elucidated. Here we report that forced GRP78 expression promotes colon cancer cell migration and invasion through upregulating MMP-2, MMP-9 and especially uPA production. These effects of GRP78 are mediated by enhancing the activation of β-catenin signaling. Interestingly, we identify that GRP78 interacts with uPA both in the cells and in the culture medium, suggesting that GRP78 protein is likely to directly facilitate uPA secretion via protein-protein interaction. Taken together, our findings demonstrate for the first time that besides stimulation of cell motility, GRP78 can act by increasing proteases production to promote tumor cell invasion. [BMB Reports 2014; 47(8): 445-450]

Tissue invasion and metastasis: Molecular, biological and clinical perspectives

Cancer is a key health issue across the world, causing substantial patient morbidity and mortality. Patient prognosis is tightly linked with metastatic dissemination of the disease to distant sites, with metastatic diseases accounting for a vast percentage of cancer patient mortality. While advances in this area have been made, the process of cancer metastasis and the factors governing cancer spread and establishment at secondary locations is still poorly understood. The current article summarizes recent progress in this area of research, both in the understanding of the underlying biological processes and in the therapeutic strategies for the management of metastasis. This review lists the disruption of E-cadherin and tight junctions, key signaling pathways, including urokinase type plasminogen activator (uPA), phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene (PI3K/AKT), focal adhesion kinase (FAK), β-catenin/zinc finger E-box binding homeobox 1 (ZEB-1) and transforming growth factor beta (TGF-β), together with inactivation of activator protein-1 (AP-1) and suppression of matrix metalloproteinase-9 (MMP-9) activity as key targets and the use of phytochemicals, or natural products, such as those from Agaricus blazei, Albatrellus confluens, Cordyceps militaris, Ganoderma lucidum, Poria cocos and Silybum marianum, together with diet derived fatty acids gamma linolenic acid (GLA) and eicosapentanoic acid (EPA) and inhibitory compounds as useful approaches to target tissue invasion and metastasis as well as other hallmark areas of cancer. Together, these strategies could represent new, inexpensive, low toxicity strategies to aid in the management of cancer metastasis as well as having holistic effects against other cancer hallmarks.

Upregulation of heat shock proteins (HSPA12A, HSP90B1, HSPA4, HSPA5 and HSPA6) in tumour tissues is associated with poor outcomes from HBV-related early-stage hepatocellular carcinoma

BACKGROUND

Heat shock proteins (HSPs) are overexpressed in human hepatocellular carcinoma (HCC) tissue and correlate with aggressiveness and prognosis of HCC.

METHODS

Using the GSE14520 microarray expression profile from Gene Expression Omnibus, we compared HSP gene expression between tumour and non-tumour tissues and correlated this with outcomes in HCC patients.

RESULTS

We analysed 220 hepatitis B virus (HBV)-related HCC patients and 25 HSPs in this study. With the exception of HSPA4L, HSPA12A and HSPB8, members of the HSP family, including HSPH1, HSPBP1, HSPA1A, HSPA1B, HSPA1L, HSPA2, HSPA4, HSPA5, HSPA8, HSPA9, HSPAA1, HSPAB1, HSPA14, HSPB11, HSPA13, HSP90B1 and HSPBAP1, were all overexpressed in tumour tissues (all P < 0.001). In contrast, HSPB6, HSPB7, HSPA6, HSPB2 and HSPB3 were upregulated in non-tumour tissues (all P < 0.001). Multivariate analysis showed that cirrhosis (HR = 5.282, 95% CI = 1.294-21.555, P = 0.02), Barcelona Clinic liver cancer (BCLC) staging (HR = 2.151, 95% CI = 1.682-2.750, P < 0.001), HSPA12A (HR = 1.042, 95% CI = 1.003-1.082, P = 0.033) and HSP90B1 (HR = 1.001, 95% CI = 1.000-1.001, P = 0.011) were negatively associated with survival of HBV-related HCC patients. Furthermore, advanced BCLC staging (HR = 1.797, 95% CI = 1.439-2.244, P < 0.001) was also associated with earlier recurrence of HCC. The high expression of HSPA4 (HR = 1.002, 95% CI = 1.000-1.004, P = 0.019), HSPA5 (HR = 1.0, 95% CI = 1.0-1.0, P = 0.046) and HSPA6 (HR = 1.008, 95% CI = 1.001-1.015, P = 0.021) was similarly associated with HCC recurrence.

CONCLUSIONS

The expression of most HSPs was higher in tumour tissues than in non-tumour tissues. High BCLC staging scores, advanced cirrhosis and the overexpression of HSPA12A and HSP90B1 might be associated with poor survival from HCC, whereas high levels of HSPA4, HSPA5 and HSPA6 might be associated with earlier recurrence of HCC.

Nanoparticles inhibit cancer cell invasion and enhance antitumor efficiency by targeted drug delivery via cell surface-related GRP78

Nanoparticles (NPs) which target specific agents could effectively recognize the target cells and increase the stability of chemical agents by encapsulation. As such, NPs have been widely used in cancer treatment research. Recently, over 90% of treatment failure cases in patients with metastatic cancer were attributed to resistance to chemotherapy. Surface-exposed glucose-regulated protein of 78 kDa (GRP78) is expressed highly on many tumor cell surfaces in many human cancers and is related to the regulation of invasion and metastasis. Herein, we report that NPs conjugated with antibody against GRP78 (mAb GRP78-NPs) inhibit the adhesion, invasion, and metastasis of hepatocellular carcinoma (HCC) and promote drug delivery of 5-fluorouracil into GRP78 high-expressed human hepatocellular carcinoma cells. Our new findings suggest that mAb GRP78-NPs could enhance drug accumulation by effectively transporting NPs into cell surface GRP78-overexpressed human hepatocellular carcinoma cells and then inhibit cell proliferation and viability and induce cell apoptosis by regulating caspase-3. In brief, mAb GRP78-NPs effectively inhibit cancer cell invasion and enhance antitumor efficiency by targeted drug delivery.