A peptide derived from phage display library exhibits anti-tumor activity by targeting GRP78 in gastric cancer multidrug resistance cells

Peptides for microbe-induced cancers: latest therapeutic strategies and their advanced technologies

Cancer is a significant global health concern associated with multiple distinct factors, including microbial and viral infections. Numerous studies have elucidated the role of microorganisms, such as Helicobacter pylori (H. pylori), as well as viruses for example human papillomavirus (HPV), hepatitis B virus (HBV), and hepatitis C virus (HCV), in the development of human malignancies. Substantial attention has been focused on the treatment of these microorganism- and virus-associated cancers, with promising outcomes observed in studies employing peptide-based therapies. The current paper provides an overview of microbe- and virus-induced cancers and their underlying molecular mechanisms. We discuss an assortment of peptide-based therapies which are currently being developed, including tumor-targeting peptides and microbial/viral peptide-based vaccines. We describe the major technological advancements that have been made in the design, screening, and delivery of peptides as anticancer agents. The primary focus of the current review is to provide insight into the latest research and development in this field and to provide a realistic glimpse into the future of peptide-based therapies for microbe- and virus-induced neoplasms.

Chemical Strategies towards the Development of Effective Anticancer Peptides

Cancer is increasingly recognized as one of the primary causes of death and has become a multifaceted global health issue. Modern medical science has made significant advancements in the diagnosis and therapy of cancer over the past decade. The detrimental side effects, lack of efficacy, and multidrug resistance of conventional cancer therapies have created an urgent need for novel anticancer therapeutics or treatments with low cytotoxicity and drug resistance. The pharmaceutical groups have recognized the crucial role that peptide therapeutic agents can play in addressing unsatisfied healthcare demands and how these become great supplements or even preferable alternatives to biological therapies and small molecules. Anticancer peptides, as a vibrant therapeutic strategy against various cancer cells, have demonstrated incredible anticancer potential due to high specificity and selectivity, low toxicity, and the ability to target the surface of traditional "undruggable" proteins. This review will provide the research progression of anticancer peptides, mainly focusing on the discovery and modifications along with the optimization and application of these peptides in clinical practice.

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

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

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

BACKGROUND

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

PURPOSE

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

CONCLUSIONS

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

Cell penetrating peptides: Highlighting points in cancer therapy

Cell-penetrating peptides (CPPs), first identified in HIV a few decades ago, deserved great attention in the last two decades; especially to support the penetration of anticancer drug means. In the drug delivery discipline, they have been involved in various approaches from mixing with hydrophobic drugs to the use of genetically conjugated proteins. The early classification as cationic and amphipathic CPPs has been extended to a few more classes such as hydrophobic and cyclic CPPs so far. Developing potential sequences utilized almost all methods of modern science: choosing high-efficiency peptides from natural protein sequences, sequence-based comparison, amino acid substitution, obtaining chemical and/or genetic conjugations, in silico approaches, in vitro analysis, animal experiments, etc. The bottleneck effect in this discipline reveals the complications that modern science faces in drug delivery research. Most CPP-based drug delivery systems (DDSs) efficiently inhibited tumor volume and weight in mice, but only in rare cases reduced their levels and continued further processes. The integration of chemical synthesis into the development of CPPs made a significant contribution and even reached the clinical stage as a diagnostic tool. But constrained efforts still face serious problems in overcoming biobarriers to reach further achievements. In this work, we reviewed the roles of CPPs in anticancer drug delivery, focusing on their amino acid composition and sequences. As the most suitable point, we relied on significant changes in tumor volume in mice resulting from CPPs. We provide a review of individual CPPs and/or their derivatives in a separate subsection.

Cell surface GRP78: a potential mechanism of therapeutic resistant tumors

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

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.

Multidrug Resistance in Cancer: Understanding Molecular Mechanisms, Immunoprevention and Therapeutic Approaches

Cancer is one of the leading causes of death worldwide. Several treatments are available for cancer treatment, but many treatment methods are ineffective against multidrug-resistant cancer. Multidrug resistance (MDR) represents a major obstacle to effective therapeutic interventions against cancer. This review describes the known MDR mechanisms in cancer cells and discusses ongoing laboratory approaches and novel therapeutic strategies that aim to inhibit, circumvent, or reverse MDR development in various cancer types. In this review, we discuss both intrinsic and acquired drug resistance, in addition to highlighting hypoxia- and autophagy-mediated drug resistance mechanisms. Several factors, including individual genetic differences, such as mutations, altered epigenetics, enhanced drug efflux, cell death inhibition, and various other molecular and cellular mechanisms, are responsible for the development of resistance against anticancer agents. Drug resistance can also depend on cellular autophagic and hypoxic status. The expression of drug-resistant genes and the regulatory mechanisms that determine drug resistance are also discussed. Methods to circumvent MDR, including immunoprevention, the use of microparticles and nanomedicine might result in better strategies for fighting cancer.

Decoy receptor 2 mediates the apoptosis-resistant phenotype of senescent renal tubular cells and accelerates renal fibrosis in diabetic nephropathy

Apoptotic resistance leads to persistent accumulation of senescent cells and sustained expression of a senescence-associated secretory phenotype, playing an essential role in the progression of tissue fibrosis. However, whether senescent renal tubular epithelial cells (RTECs) exhibit an apoptosis-resistant phenotype, and the role of this phenotype in diabetic nephropathy (DN) remain unclear. Our previous study was the first to demonstrate that decoy receptor 2 (DcR2) is associated with apoptotic resistance in senescent RTECs and renal fibrosis. In this study, we aimed to further explore the mechanism of DcR2 in apoptosis-resistant RTECs and renal fibrosis in DN. DcR2 was co-localized with fibrotic markers (α-SMA, collagen IV, fibronectin), senescent marker p16, and antiapoptotic proteins FLIP and Bcl2 but rarely co-localized with caspase 3 or TUNEL. DcR2 overexpression promoted renal fibrosis in mice with streptozotocin (STZ)-induced DN, as evidenced by augmented Masson staining and upregulated expression of fibrotic markers. DcR2 overexpression also enhanced FLIP expression while reducing the expression of pro-apoptotic proteins (caspases 8 and 3) in senescent RTECs, resulting in apoptotic resistance. In contrast, DcR2 knockdown produced the opposite effects in vitro and in vivo. Moreover, quantitative proteomics and co-immunoprecipitation experiments demonstrated that DcR2 interacted with glucose-related protein 78 kDa (GRP78), which has been shown to promote apoptotic resistance in cancer. GRP78 exhibited co-localization with senescent and antiapoptotic markers but was rarely co-expressed with caspase 3 or TUNEL. Additionally, GRP78 knockdown decreased the apoptosis resistance of HG-induced senescent RTECs with upregulated cleaved caspase 3 and increased the percentage of apoptotic RTECs. Mechanistically, DcR2 mediated apoptotic resistance in senescent RTECs by enhancing GRP78-caspase 7 interactions and promoting Akt phosphorylation. Thus, DcR2 mediated the apoptotic resistance of senescent RTECs and renal fibrosis by interacting with GRP78, indicating that targeting the DcR2-GRP78 axis represents a promising therapeutic strategy for DN.

MiR-181c sensitizes ovarian cancer cells to paclitaxel by targeting GRP78 through the PI3K/Akt pathway

Primary cytoreductive surgery with platinum-taxane-based chemotherapy is the standard treatment for ovarian cancer (OC) patients; however, resistance to chemotherapy is a contributing factor to OC mortality. Paclitaxel (PTX), the most widely used taxane, has become the first-line drug against OC. The molecular mechanism of PTX resistance is different from that of platinum-based agents and is still not completely elucidated. Our previous study showed that glucose-regulated protein 78 (GRP78) is involved in the resistance of OC cells to PTX. However, little is known regarding endogenous inhibitors of this gene. MicroRNAs (miRNAs) play critical roles in the regulation of gene expression; therefore, we sought to identify miRNA(s) with potential to target GRP78 under the hypothesis that miRNA(s) could serve as potential therapeutic targets. Here, we show that miR-181c, predicted to target GRP78, was downregulated in PTX-resistant OC cells and tissues. MiR-181c downregulated GRP78 expression and induced apoptosis by directly targeting its 3'-untranslated region (UTR). Overexpression of miR-181c sensitized resistant OC to PTX by inhibiting the PI3K/Akt pathway in vitro and in vivo. Taken together, our findings indicate that the delivery of miR-181c can efficiently suppress GRP78 expression and GRP78-mediated PTX resistance in OC and suggest that this strategy has therapeutic potential.

Tumor microenvironment responsive Mn3O4 nanoplatform for in vivo real-time monitoring of drug resistance and photothermal/chemodynamic synergistic therapy of gastric cancer

Background

Postoperative chemotherapy for gastric cancer often causes multidrug resistance (MDR), which has serious consequences for therapeutic effects. Individualized treatment based on accurate monitoring of MDR will greatly improve patient survival.

Results

In this article, a self-enhanced Mn₃O₄ nanoplatform (MPG NPs) was established, which can react with glutathione to produce Mn²⁺ to enhance T1-weighted magnetic resonance imaging (MRI) and mediate in vivo real-time MDR monitoring. In vitro MRI results showed that MRI signals could be enhanced in the presence of hydrogen peroxide and glutathione and at acidic pH. In vivo MRI results indicated that MPG NPs could specifically target MDR cells, thereby realizing real-time monitoring of MDR in gastric cancer. Furthermore, MPG NPs have good chemodynamic activity, which can convert the endogenous hydrogen peroxide of tumor cells into highly toxic hydroxyl radical through Fenton-like reaction at acidic pH to play the role of chemodynamic therapy. In addition, Mn₃O₄ can significantly enhance the chemodynamic therapy effect because of its good photothermal conversion effect. Furthermore, in situ photothermal/chemodynamic synergistic therapy obtained remarkable results, the tumors of the mice in the synergistic therapy group gradually became smaller or even disappeared.

Conclusions

MPG NPs have good biocompatibility, providing a good nanoplatform for real-time monitoring and precise diagnosis and treatment of MDR in gastric cancer.

Graphical Abstract

Supplementary information

The online version contains supplementary material available at 10.1186/s12951-022-01441-6.

GBP2 facilitates the progression of glioma via regulation of KIF22/EGFR signaling

Identifying the mechanism of glioma progression is critical for diagnosis and treatment. Although studies have shown that guanylate-binding protein 2(GBP2) has critical roles in various cancers, its function in glioma is unclear. In this work, we demonstrate that GBP2 has high expression levels in glioma tissues. In glioma cells, depletion of GBP2 impairs proliferation and migration, whereas overexpression of GBP2 enhances proliferation and migration. Regarding the mechanism, we clarify that epidermal growth factor receptor (EGFR) signaling is regulated by GBP2, and also demonstrate that GBP2 interacts directly with kinesin family member 22(KIF22) and regulates glioma progression through KIF22/EGFR signaling in vitro and in vivo. Therefore, our study provides new insight into glioma progression and paves the way for advances in glioma treatment.

Selective targeting of the novel CK-10 nanoparticles to the MDA-MB-231 breast cancer cells

The main objective of this project was to formulate novel decorated amphiphilic PLGA nanoparticles aiming for the selective delivery of the novel peptide (CK-10) to the cancerous/tumor tissue. Novel modified microfluidic techniques were used to formulate the nanoparticles. This technique was modified by using of Nano Assemblr associated with salting out of the organic solvent using K₂HPO₄. This modification is associated with higher peptide loading efficiencies, smaller size and higher uniformity. Size, zeta potential & qualitative determination of the adsorbed targeting ligands were measured by dynamic light scattering and laser anemometry techniques using the zeta sizer. Quantitative estimation of the adsorbed targeting ligands was done by colorimetry and spectrophotometric techniques. Qualitative and quantitative uptakes of the various PLGA nanoparticles were examined by the fluorescence microscope and the flow cytometer while the cytotoxic effect of the nanoparticles was measured by the colorimetric MTT assay. PLGA/poloxamer.FA, PLGA/poloxamer.HA, and PLGA/poloxamer.Tf have breast cancer MDA. MB321 cellular uptakes 83.8, 75.43 & 69.37 % which are higher than those of the PLGA/B cyclodextrin.FA, PLGA/B cyclodextrin.HA and PLGA/B cyclodextrin.Tf 80.87, 74.47 & 64.67 %. Therefore, PLGA/poloxamer.FA and PLGA/poloxamer.HA show higher cytotoxicity than PLGA/ poloxamer.Tf with lower breast cancer MDA-MB-231 cell viabilities 30.74, 39.15 & 49.23 %, respectively. The design of novel decorated amphiphilic CK-10 loaded PLGA nanoparticles designed by the novel modified microfluidic technique succeeds in forming innovative anticancer formulations candidates for therapeutic use in aggressive breast cancers.

Arginine-Arginine-Leucine Peptide Targeting Heat Shock Protein 70 for Cancer Imaging

Arg-Arg-Leu (RRL) is a potent tumor-homing tripeptide. However, the binding target is unclear. In this study, we intended to identify the binding target of RRL and evaluate the tumor targeting of ^99mTc-MAG₃-RRL in vivo. Biotin-RRL, 5-TAMRA-RRL, and ^99mTc-MAG₃-RRL were designed to trace the binding target and tumor lesion. Immunoprecipitation-mass spectrometry was conducted to identify the candidate proteins and determination of the subcellular localization was also performed. A pull-down assay was performed to demonstrate the immunoprecipitate. Fluorescence colocalization and cell uptake assays were performed to elucidate the correlation between the selected binding protein and RRL, and the internalization mechanism of RRL. Biodistribution and in vivo imaging were performed to evaluate the tumor accumulation and targeting of ^99mTc-MAG₃-RRL. The target for RRL was screened to be heat shock protein 70 (HSP70). The prominent uptake distribution of RRL was concentrated in the membrane and cytoplasm. A pull-down assay demonstrated the existence of HSP70 in the biotin-RRL captured complex. Regarding fluorescence colocalization and cell uptake assays, RRL may interact with HSP70 at the nucleotide-binding domain (NBD). Clathrin-dependent endocytosis and macropinocytosis could be a vital internalization mechanism of RRL. In vivo imaging and biodistribution both demonstrated that ^99mTc-MAG₃-RRL can trace tumors with satisfactory accumulation in hepatoma xenograft mice. The radioactive signals accumulated in tumor lesions can be blocked by VER-155008, which can bind to the NBD of HSP70. Our findings revealed that RRL may interact with HSP70 and that ^99mTc-MAG₃-RRL could be a prospective probe for visualizing overexpressed HSP70 tumor sections.

Molecular targeted treatment and drug delivery system for gastric cancer

Gastric cancer is still a major cancer worldwide. The early diagnosis rate of gastric cancer in most high incidence countries is low. At present, the overall treatment effect of gastric cancer is poor, and the median overall survival remains low. Most of the patients with gastric cancer are in an advanced stage when diagnosed, and drug treatment has become the main means. Thus, new targeted drugs and therapeutic strategies are the hope of improving the therapeutic effect of gastric cancer. In this review, we summarize the new methods and advances of targeted therapy for gastric cancer, including novel molecular targeted therapeutic agents and drug delivery systems, with a major focus on the development of drug delivery systems (drug carriers and targeting peptides). Elaborating these new methods and advances will contribute to the management of gastric cancer.

Sequenced Combinations of Cisplatin and Selected Phytochemicals towards Overcoming Drug Resistance in Ovarian Tumour Models

In the present study, cisplatin, artemisinin, and oleanolic acid were evaluated alone, and in combination, on human ovarian A2780, A2780^ZD0473R, and A2780^cisR cancer cell lines, with the aim of overcoming cisplatin resistance and side effects. Cytotoxicity was assessed by MTT reduction assay. Combination index (CI) values were used as a measure of combined drug effect. MALDI TOF/TOF MS/MS and 2-DE gel electrophoresis were used to identify protein biomarkers in ovarian cancer and to evaluate combination effects. Synergism from combinations was dependent on concentration and sequence of administration. Generally, bolus was most synergistic. Moreover, 49 proteins differently expressed by 2 ≥ fold were: CYPA, EIF5A1, Op18, p18, LDHB, P4HB, HSP7C, GRP94, ERp57, mortalin, IMMT, CLIC1, NM23, PSA3,1433Z, and HSP90B were down-regulated, whereas hnRNPA1, hnRNPA2/B1, EF2, GOT1, EF1A1, VIME, BIP, ATP5H, APG2, VINC, KPYM, RAN, PSA7, TPI, PGK1, ACTG and VDAC1 were up-regulated, while TCPA, TCPH, TCPB, PRDX6, EF1G, ATPA, ENOA, PRDX1, MCM7, GBLP, PSAT, Hop, EFTU, PGAM1, SERA and CAH2 were not-expressed in A2780^cisR cells. The proteins were found to play critical roles in cell cycle regulation, metabolism, and biosynthetic processes and drug resistance and detoxification. Results indicate that appropriately sequenced combinations of cisplatin with artemisinin (ART) and oleanolic acid (OA) may provide a means to reduce side effects and circumvent platinum resistance.

Tunicamycin promotes metastasis through upregulating endoplasmic reticulum stress induced GRP78 expression in thyroid carcinoma

Background

Thyroid cancer (TC) is the most common type of endocrine malignancy and its incidence is increasing over years. Conventional surgery, radiotherapy and chemotherapy are difficult to improve the significant effects of it due to aggression and metastasis of poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC), and these are regarded as the most malignant types of TC. Glucose-regulated protein (GRP78) is the key molecule of tumor growth, apoptosis and metastasis. However, the underlying mechanisms of GRP78 in TC still require discussion. This study aimed to explore the role of GRP78 and its potential mechanism in TC.

Results

GRP78 expression was increased in TC tissues when compared with adjacent normal tissues. Besides, down-regulation of GRP78 significantly inhibited the metastatic and proliferative ability of ATC cells in in vitro studies. In addition, tunicamycin-induced ER stress up-regulated the expression of GRP78, PERK and XBP1 as well as reversed the metastatic ability of GRP78 in ATC cells. Bioinformatics and statistical analysis of gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways for RNA-sequencing data with regard to si-GRP78 and si-control showed that GRP78 might regulate the ability of metastasis through extracellular matrix (ECM) remodeling in ATC cells, as well as the expression of ECM components such as COL1A1 and MMP13, which were highly relevant to ATC cells. The analysis of GEPIA database confirmed that high genomic amplification of MMP13 and COL1A1 in TC tissues showed correlation with TNM stage. Further western blotting analysis showed that MMP13 might be the target of GRP78 in ATC cells and ER stress could activate the expression of MMP13 that is suppressed by GRP78 depletion.

Conclusions

GRP78 acts as an important regulator of metastasis under ER stress. In addition, the function of GRP78 might be mediated by ECM remodeling in ATC cells, implicating it as a therapeutic target in TC.

Cell-penetrating peptides in oncologic pharmacotherapy: A review

Cancer is the second leading cause of death in the world and its treatment is extremely challenging, mainly due to its complexity. Cell-Penetrating Peptides (CPPs) are peptides that can transport into the cell a wide variety of biologically active conjugates (or cargoes), and are, therefore, promising in the treatment and in the diagnosis of several types of cancer. Some notable examples are TAT and Penetratin, capable of penetrating the central nervous system (CNS) and, therefore, acting in cancers of this system, such as Glioblastoma Multiforme (GBM). These above-mentioned peptides, conjugated with traditional chemotherapeutic such as Doxorubicin (DOX) and Paclitaxel (PTX), have also been shown to induce apoptosis of breast and liver cancer cells, as well as in lung cancer cells, respectively. In other cancers, such as esophageal cancer, the attachment of Magainin 2 (MG2) to Bombesin (MG2B), another CPP, led to pronounced anticancer effects. Other examples are CopA3, that selectively decreased the viability of gastric cancer cells, and the CPP p28. Furthermore, in preclinical tests, the anti-tumor efficacy of this peptide was evaluated on human breast cancer, prostate cancer, ovarian cancer, and melanoma cells in vitro, leading to high expression of p53 and promoting cell cycle arrest. Despite the numerous in vitro and in vivo studies with promising results, and the increasing number of clinical trials using CPPs, few treatments reach the expected clinical efficacy. Usually, their clinical application is limited by its poor aqueous solubility, immunogenicity issues and dose-limiting toxicity. This review describes the most recent advances and innovations in the use of CPPs in several types of cancer, highlighting their crucial importance for various purposes, from therapeutic to diagnosis. Further clinical trials with these peptides are warranted to examine its effects on various types of cancer.

Immunoprecipitation and mass spectrometry define TET1 interactome during oligodendrocyte differentiation

Ten-eleven translocation (TET) proteins, encoding dioxygenase for DNA hydroxymethylation, are important players in nervous system development and disease. In addition to their proverbial enzymatic role, TET proteins also possess non-enzymatic activity and function in multiple protein-protein interaction networks, which remains largely unknown during oligodendrocyte differentiation. To identify partners of TET1 in the myelinating cells, we performed proteome-wide analysis using co-immunoprecipitation coupled to mass spectrometry (IP-MS) in purified oligodendrocyte precursor cells (OPCs) and mature oligodendrocytes (mOLs), respectively. Following a stringent selection of MS data based on identification reliability and protein enrichment, we identified a core set of 1211 partners that specifically interact with TET1 within OPCs and OLs. Analysis of the biological process and pathways associated with TET1-interacting proteins indicates a significant enrichment of proteins involved in regulation of cellular protein localization, cofactor metabolic process and regulation of catabolic process, et al. We further validated TET1 interactions with selected partners. Overall, this comprehensive analysis of the endogenous TET1 interactome during oligodendrocyte differentiation suggest its novel mechanism in regulating oligodendrocyte homeostasis and provide comprehensive insight into the molecular pathways associated with TET1.

Cell surface GRP78 signaling: An emerging role as a transcriptional modulator in cancer

Cancer cells acquire dysregulated gene expression to establish specific transcriptional dependencies and their underlying mechanisms that are ultimately responsible for this addictions have not been fully elucidated. Glucose-regulated protein 78 (GRP78) is a stress-inducible, multifunctional, prosurvival, endoplasmic reticulum chaperone in the heat shock protein 70 family. Expression of cell surface GRP78 (CS-GRP78) is associated with increased malignant behavior and resistance to chemotherapy and radiotherapy by endowing various cancer cells with increased proliferative ability, altered metabolism, improved survival, and augmented invasive and metastatic potential. Emerging evidence has highlighted an unusual role of CS-GRP78 in regulating transcription factors (TFs) by mediating various signaling pathways involved in malignant transformation, metabolic reprogramming, and tumor progression. During the last decade, we targeted CS-GRP78 with C38 monoclonal antibody (C38 Mab) in numerous studies, which have highlighted the epigenetic interplay between CS-GRP78 and various TFs including c-MYC, Yes-associated protein/transcriptional coactivator with PDZ-binding motif, c-Fos, and histone acetylation to potentiate subsequent modulation of tumorigenesis, invasion, and metastasis. Here, we summarize the current state of knowledge about the role of CS-GRP78 in cancer development and progression, including epigenetic regulation and sheds light on CS-GRP78 as vulnerable target for cancer therapy. Overall, this review focuses on the mechanisms of TFs that are behind the transcriptional dysregulation in cancer and lays the groundwork for rational therapeutic use of C38 Mab based on CS-GRP78 biology.

GMBP1-conjugated manganese oxide nanoplates for in vivo monitoring of gastric cancer MDR using magnetic resonance imaging

Multidrug resistance (MDR) is a huge challenge for gastric cancer chemotherapy. Therefore, MDR accurate monitoring is of great significance for the treatment of gastric cancer. GMBP1, an extracellular internalization peptide, can target MDR gastric cancer cells through specific binding to GRP78, which is an MDR-related protein that is overexpressed in gastric cancer cells. Herein, we constructed GMBP1 conjugated Mn₃O₄ nanoplates (Mn₃O₄@PEG-GMBP1 NPs) for in vivo monitoring of MDR gastric cancer through magnetic resonance imaging (MRI). The generated Mn₃O₄@PEG-GMBP1 NPs had a size of about 11 nm and exhibited a good colloidal stability in PBS and in 10% FBS medium. Serial in vivo MRI studies in mice demonstrated that the magnetic resonance signal intensity, at the tumor site, reached a peak at 3 h after tail vein injection of Mn₃O₄@PEG-GMBP1 NPs. The specific targeting ability of MDR gastric cancer cells (SGC7901/ADR) by Mn₃O₄@PEG-GMBP1 NPs was authenticated in vitro, in vivo and by immunofluorescence analysis experiments. The systematic safety evaluation indicated that the toxicity of Mn₃O₄@PEG-GMBP1 NPs in mice was negligible. Therefore, the GMBP1 conjugated Mn₃O₄ nanoplates can be clinically used for accurate imaging and monitoring of MDR gastric cancer.

Data on the sequence-derived properties of gastric cancer - binding peptides

The article presents a dataset containing nine classes of calculated sequence-derived descriptors for 78 peptide sequences, 21 of which demonstrate the ability to bind with gastric cancer cells. The datasaet was used in the paper "A screening algorithm for gastric cancer binding peptides" [1] for the creation of a classification model that can predict the ability of a given peptide sequence to bind with gastric cancer cells. The 78 peptide sequences were extracted from a systematic literature search, and the various peptide descriptors were calculated using the R package "Peptides". The nine calculated sequence-derived descriptor classes are the Blosum indices, Cruciani properties, FASGAI vectors, Kidera factors, ProtFP, ST-scales, T-scales, VHSE scales, and Z-scales. The resulting dataset, which is composed of over 4000 data points, offers a rich resource for further protochemometric analyses of the curated peptide sequences relevant to cancer diagnostics and therapeutics.

Phage nanofibers in nanomedicine: Biopanning for early diagnosis, targeted therapy, and proteomics analysis

Display of a peptide or protein of interest on the filamentous phage (also known as bacteriophage), a biological nanofiber, has opened a new route for disease diagnosis and therapy as well as proteomics. Earlier phage display was widely used in protein-protein or antigen-antibody studies. In recent years, its application in nanomedicine is becoming increasingly popular and encouraging. We aim to review the current status in this research direction. For better understanding, we start with a brief introduction of basic biology and structure of the filamentous phage. We present the principle of phage display and library construction method on the basis of the filamentous phage. We summarize the use of the phage displayed peptide library for selecting peptides with high affinity against cells or tissues. We then review the recent applications of the selected cell or tissue targeting peptides in developing new targeting probes and therapeutics to advance the early diagnosis and targeted therapy of different diseases in nanomedicine. We also discuss the integration of antibody phage display and modern proteomics in discovering new biomarkers or target proteins for disease diagnosis and therapy. Finally, we propose an outlook for further advancing the potential impact of phage display on future nanomedicine. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Research Progress Evaluating the Function and Mechanism of Anti-Tumor Peptides

Malignant tumors cause a high mortality rate worldwide, and they severely threaten human health and negatively affect the economy. Despite the advancements in tumor-related molecular genetics and effective new processes in anti-tumor drug development, the anti-tumor drugs currently used in clinical practice are inadequate due to their poor efficacy or severe side effects. Therefore, developing new safe and efficient drugs is a top priority for curing cancer. The peptide has become a suitable agent due to its exact molecular weight between whole protein and small molecule, and it has high targeting ability, high penetrability, low immunogenicity, and is convenient to synthesize and easy to modify. Because of these advantages, peptides have excellent prospect for application as anti-tumor agents. This article reviews the recent research progress evaluating anti-tumor peptides and their anti-tumor mechanisms, and may act as a reference for the future development and clinical application of anti-tumor peptides.

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Role of G protein-coupled receptor 1 in choriocarcinoma progression

Choriocarcinoma is characterized by malignant proliferation and transformation of trophoblasts and is currently treated with systemic chemotherapeutic agents. The lack of specific targets for chemotherapeutic agents results in indiscriminate drug distribution. In our study, we aimed to delineate the mechanism by which G protein-coupled receptor 1 (GPR1) regulates the development of choriocarcinoma and thus investigated GPR1 as a prospective chemotherapeutic target. In this study, GPR1 expression levels were examined in several trophoblast cell lines. We found significantly higher GPR1 expression in choriocarcinoma cells (JEG3 and BeWo) than in normal trophoblast cells (HTR-8/SVneo). Additionally, we studied the role of GPR1 in choriocarcinoma in vitro and in vivo. GPR1 knockdown suppressed proliferation, invasion, and Akt and ERK phosphorylation in vitro and slowed tumor growth in vivo. Interestingly, GPR1 overexpression promoted increased proliferation, invasion, and Akt and ERK phosphorylation in vitro. Furthermore, we identified a specific GPR1-binding seven-amino acid peptide, LRH7-G3, that might also suppress choriocarcinoma in vitro and in vivo through phage display. Our study is the first to report that GPR1 may play a role in regulating choriocarcinoma progression through the Akt and ERK pathways. GPR1 could be a promising potential pharmaceutical target for choriocarcinoma.

The tumorigenic role of DSPP and its potential regulation of the unfolded protein response and ER stress in oral cancer cells

Dentin sialophosphoprotein (DSPP) is upregulated in various human cancers, including head and neck squamous cell carcinoma. Cancer cells are commonly found under constant endoplasmic reticulum (ER) stress and exhibit increased levels of misfolded proteins, due to gene mutations and a stressful microenvironment. The present study examined the effects of DSPP silencing on the regulation of ER stress and the unfolded protein response (UPR) in oral cancer cells. A recently established stable DSPP short hairpin (sh)RNA-silenced OSC2 oral cancer cell line was used. The mRNA expression levels of ER stress-associated proteins, including 78 kDa glucose-regulated protein (GRP78), sarcoplasmic/endoplasmic reticulum calcium ATPase 2b (SERCA2b), inositol 1,4,5-trisphosphate receptor (IP3r), protein kinase R-like endoplasmic reticulum kinase (PERK), serine/threonine-protein kinase/endoribonuclease IRE1 (IRE1), activating transcription factor 6 (ATF6) and matrix metalloproteinase 20 (MMP20), were assessed by reverse transcription-quantitative polymerase chain reaction. The expression levels of apoptosis-related [B‑cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax) and cytochrome c] and cell proliferation-related [proliferating cell nuclear antigen (PCNA)] proteins were analyzed by western blotting. Cell viability, apoptosis and migration were monitored by MTT assay, Annexin V-fluorescein isothiocyanate flow cytometry and wound-healing assay, respectively. In transiently transfected puromycin‑free OSC2 cells, DSPP silencing markedly downregulated the mRNA expression levels of major ER stress regulators, including GRP78, SERCA2b, PERK, IRE1 and ATF6, as well as MMP20. DSPP silencing also resulted in decreased cell viability and migration, and enhanced apoptosis. Furthermore, PCNA and Bcl2 levels were decreased, whereas Bax and cytochrome c protein levels were increased in DSPP-silenced OSC2 cells. Sustained puromycin treatment partially counteracted the effects of DSPP silencing on the mRNA expression levels of ER stress-related proteins and MMP20, and on the migratory capacity of OSC2 cells. However, following puromycin treatment of DSPP-silenced cells, cell viability was further reduced and apoptosis was enhanced. In conclusion, these data provide evidence to suggest that DSPP may be involved in ER stress mechanisms in oral squamous cell carcinoma, since its downregulation in OSC2 cells led to significant alterations in the levels of major ER stress-associated proteins, and subsequent collapse of the UPR system.

Identification of a peptide for folate receptor alpha by phage display and its tumor targeting activity in ovary cancer xenograft

The expression level of folate receptor alpha (FRα) is located highly rate in ovarian cancer though it is remained absent in normal tissues. This highly tumor restricted expression profile makes FRα a promising target for tumor therapy and diagnosis. In this research we report a FRα binding peptide C7(Met-His-Thr-Ala-Pro-Gly-Trp-Gly-Tyr-Arg-Leu-Ser) discovered by phage display and this peptide showed specific binding to FRα expressing cells by cell ELISA and flow cytometry. Tumor targeting ability of C7 was proved in vivo by both phage homing experiment and fluorescence imaging. C7 can be internalized by SKOV3 cells and its affinity to FRα was determined by MST. The molecular recognition was revealed by structure modeling, suggesting its binding mode with FRα.

Novel peptide GX1 inhibits angiogenesis by specifically binding to transglutaminase-2 in the tumorous endothelial cells of gastric cancer

The clinical application of GX1, an optimal gastric cancer (GC) targeting peptide, is greatly limited because its receptor in the GC vasculature is unknown. In this study, we screened the candidate receptor of GX1, transglutaminase-2(TGM2), by co-immunoprecipitation (co-IP) combined with mass spectrometry. We found that TGM2 was up-regulated in GC vascular endothelial cells and that GX1 receptor expression was suppressed correspondingly after TGM2 downregulation. A highly consistent co-localization of GX1 receptor and TGM2 was detected at both the cellular and tissue levels. High TGM2 expression was evident in GC tissues from patients with poor prognosis. After TGM2 downregulation, the GX1-mediated inhibition of proliferation and migration and the induction of the apoptosis of GC vascular endothelial cells were weakened or even reversed. Finally, we observed that GX1 could inhibit the GTP-binding activity of TGM2 by reducing its intracellular distribution and downregulating its downstream molecular targets (nuclear factor-kappa B, NF-κB; hypoxia-inducible factor 1-α, HIF1α) in GC vascular endothelial cells. Our study confirms that peptide GX1 can inhibit angiogenesis by directly binding to TGM2, subsequently reducing the GTP-binding activity of TGM2 and thereby suppressing its downstream pathway(NF-κB/HIF1α). Our conclusions suggest that GX1/TGM2 may provide a new target for the diagnosis and treatment of GC.

Endoplasmic reticulum chaperone glucose-regulated protein 78 in gastric cancer: An emerging biomarker

The endoplasmic reticulum (ER) is the principal organelle responsible for the synthesis, initial post-translational modification, folding, export and secretion of proteins. It is also responsible for the maintenance of cellular homeostasis. In response to cellular stress conditions including glucose deprivation, hypoxia and changes in calcium homeostasis, ER stress machinery is activated and triggers the unfolded protein response, resulting in the restoration of homeostasis or activation of cell death. Glucose-regulated protein 78 (GRP78), a molecular chaperone, may be induced by ER stress at the transcriptional and translational level. A number of studies have demonstrated that GRP78 serves an important role in tumor cell proliferation, metastasis, angiogenesis and drug-resistance. The present review systematically describes the association between GRP78 expression and gastric cancer pathogenesis, and emphasizes that GRP78 is a novel diagnostic and therapeutic biomarker of gastric cancer.

Combining GRP78 suppression and MK2206-induced Akt inhibition decreases doxorubicin-induced P-glycoprotein expression and mitigates chemoresistance in human osteosarcoma

P-glycoprotein (P-gp) overexpression is associated with poor prognosis and drug-resistance in osteosarcoma (OS), but the underlying mechanisms remain incompletely understood. Here, we examined the regulation of P-gp, GRP78, and phospho-Akt in doxorubicin (DOX)-treated OS cells. DOX induced P-gp expression, which was associated with increased GRP78 levels and Akt activation in vitro and in vivo. Functional analysis showed that Akt induces P-gp and GRP78 expression, which contributes to the DOX-induced Akt activation. Examination of the relationship between Akt and GRP78 demonstrated that GRP78 suppression attenuates the Akt activity in OS parental sensitive and resistant cells, indicating that GRP78 is required for full Akt activity. Inhibition of Akt activity using MK2206 decreased GRP78 expression in OS cells, which enhanced the inhibitory effect of MK2206 on P-gp expression. GRP78 knockdown combined with MK2206 suppressed the development of DOX resistance in OS cells and inhibited the in vivo tumor growth in the presence of DOX. These results support the development of novel therapeutic strategies that target GRP78 and Akt to sensitize OS cells for chemotherapy.

A novel vascular-targeting peptide for gastric cancer delivers low-dose TNFα to normalize the blood vessels and improve the anti-cancer efficiency of 5-fluorouracil

Various vascular-targeted agents fused with tumor necrosis factor α (TNFα) have been shown to improve drug absorption into tumor tissues and enhance tumor vascular function. TCP-1 is a peptide selected through in vivo phage library biopanning against a mouse orthotopic colorectal cancer model and is a promising agent for drug delivery. This study further investigated the targeting ability of TCP-1 phage and peptide to blood vessels in an orthotopic gastric cancer model in mice and assessed the synergistic anti-cancer effect of 5-fluorouracil (5-FU) with subnanogram TNFα targeted delivered by TCP-1 peptide. In vivo phage targeting assay and in vivo colocalization analysis were carried out to test the targeting ability of TCP-1 phage/peptide. A targeted therapy for improvement of the therapeutic efficacy of 5-FU and vascular function was performed through administration of TCP-1/TNFα fusion protein in this model. TCP-1 phage exhibited strong homing ability to the orthotopic gastric cancer after phage injection. Immunohistochemical staining suggested that and TCP-1 phage/TCP-1 peptide could colocalize with tumor vascular endothelial cells. TCP-1/TNFα combined with 5-FU was found to synergistically inhibit tumor growth, induce apoptosis and reduce cell proliferation without evident toxicity. Simultaneously, subnanogram TCP-1/TNFα treatment normalized tumor blood vessels. Targeted delivery of low-dose TNFα by TCP-1 peptide can potentially modulate the vascular function of gastric cancer and increase the drug delivery of chemotherapeutic drugs.

miR-181a Inhibits Cervical Cancer Development via Downregulating GRP78

Cervical cancer is among the most common cancers inflicting women worldwide. Understanding the pathological mechanisms of cervical cancer development is critical for identifying novel targets for cervical cancer treatment. MicroRNAs (miRs) have various roles in regulating cancer development. In this study, we investigated the potential role of miR-181a and its target in regulating cervical cancer development and chemotherapy resistance. The expression of miR-181a was evaluated and modulated in several human cervical cancer cell lines. The role of miR-181a in regulating cervical cancer growth and chemotherapy sensitivity was investigated in cell culture models and mouse tumor xenograft models. The target of miR-181a and its function were identified in cervical cancer models. We found a distinct expression profile for miR-181a in cervical cancer cell lines. Low expression of miR-181a was closely related to cervical cancer growth and oxaliplatin resistance. HSPA5/GRP78 was identified as a target of miR-181a in cervical cancer cells. Upregulation of GRP78 led to a high cell proliferation rate and oxaliplatin resistance in cervical cancer models. In a retrospective cervical cancer cohort, high GRP78 expression was correlated with poor survival. miR-181a suppressed cervical cancer development via downregulating GRP78. High expression of GRP78 is a tumor-promoting factor in cervical cancer and is thus a potential target for novel treatment.

Virus-Derived Peptides for Clinical Applications

Novel affinity agents with high specificity are needed to make progress in disease diagnosis and therapy. Over the last several years, peptides have been considered to have fundamental benefits over other affinity agents, such as antibodies, due to their fast blood clearance, low immunogenicity, rapid tissue penetration, and reproducible chemical synthesis. These features make peptides ideal affinity agents for applications in disease diagnostics and therapeutics for a wide variety of afflictions. Virus-derived peptide techniques provide a rapid, robust, and high-throughput way to identify organism-targeting peptides with high affinity and selectivity. Here, we will review viral peptide display techniques, how these techniques have been utilized to select new organism-targeting peptides, and their numerous biomedical applications with an emphasis on targeted imaging, diagnosis, and therapeutic techniques. In the future, these virus-derived peptides may be used as common diagnosis and therapeutics tools in local clinics.

Discovery of a polystyrene binding peptide isolated from phage display library and its application in peptide immobilization

Phage peptide display is a powerful technique for discovery of various target-specific ligands. However, target-unrelated peptides can often be obtained and cause ambiguous results. Peptide PB-TUP has been isolated repeatedly in our laboratory on different targets and we conducted a research on PB-TUP phage to investigate their binding properties and rate of propagation. ELISA and phage recovery assay demonstrated that PB-TUP phage had a significant superior affinity to polystyrene solid surface compared with control phage clones. In this study, some incidental bindings are excluded like blocking agents and non-specific binding of secondary antibodies. Propagation rate assays of the selected phage clones showed that the growth rate of PB-TUP phage was not superior to the control phages. Furthermore, the binding of PB-TUB to polystyrene was concentration dependent and varied with solution pH. Molecular modeling revealed that stable structures of α-helix and β-turn may contribute to the binding of PB-TUP to polystyrene plate. The PB-TUP sequence was fused to the N-terminus of peptide P2 and the fusion peptide significantly increased the binding affinity to polystyrene. The fusion peptide also enhanced the cell adhesion ability of peptide P2 with human umbilical vein endothelial cell (HUVEC). The addition of the polystyrene binding peptide provided a convenient method for peptide immobilization.

Tumor-targeting peptides from combinatorial libraries

Cancer is one of the major and leading causes of death worldwide. Two of the greatest challenges in fighting cancer are early detection and effective treatments with no or minimum side effects. Widespread use of targeted therapies and molecular imaging in clinics requires high affinity, tumor-specific agents as effective targeting vehicles to deliver therapeutics and imaging probes to the primary or metastatic tumor sites. Combinatorial libraries such as phage-display and one-bead one-compound (OBOC) peptide libraries are powerful approaches in discovering tumor-targeting peptides. This review gives an overview of different combinatorial library technologies that have been used for the discovery of tumor-targeting peptides. Examples of tumor-targeting peptides identified from each combinatorial library method will be discussed. Published tumor-targeting peptide ligands and their applications will also be summarized by the combinatorial library methods and their corresponding binding receptors.

Enhancement of Drug Sensitivity by Knockdown of HIF-1α in Gastric Carcinoma Cells

In this study, the effects of hypoxia-inducible factor-1α (HIF-1α) on gastric carcinoma (GC) drug resistance through apoptosis-related genes are investigated. First, HIF-1α-specific siRNA was synthetized and transfected into drug-resistant GC cell line OCUM-2MD3/L-OHP. Then MTT assay was applied to test the inhibition rate of GC cells by 5-fluorouracil (5-FU) and oxaliplatin (L-OHP). After that, flow cytometry (FCM) was applied to measure apoptosis rate. qPCR and Western blot assay were employed to detect HIF-1α and apoptosis-related genes. Results showed that HIF-1α in OCUM-2MD3/L-OHP cells was higher than that in OCUM-2MD3 and gastric epithelial cells. After HIF-1α-siRNA transfection, inhibition rates of 5-FU and L-OHP to tumor cells increased significantly. FCM results showed that apoptosis rate of OCUM-2MD3/L-OHP cells increased significantly. After HIF-1α-siRNA transfection, survivin and Bcl-2 decreased, whereas Bax, caspase 3, and caspase 8 increased significantly. Results from this study seem to confirm that HIF-1α getting involved in GC drug resistance is possibly due to its regulation of some apoptosis-related genes. HIF-1α may be a potential target to reverse drug resistance of GC.

Bacteriophages and phage-inspired nanocarriers for targeted delivery of therapeutic cargos

The main goal of drug delivery systems is to target therapeutic cargoes to desired cells and to ensure their efficient uptake. Recently a number of studies have focused on designing bio-inspired nanocarriers, such as bacteriophages, and synthetic carriers based on the bacteriophage structure. Bacteriophages are viruses that specifically recognize their bacterial hosts. They can replicate only inside their host cell and can act as natural gene carriers. Each type of phage has a particular shape, a different capacity for loading cargo, a specific production time, and their own mechanisms of supramolecular assembly, that have enabled them to act as tunable carriers. New phage-based technologies have led to the construction of different peptide libraries, and recognition abilities provided by novel targeting ligands. Phage hybridization with non-organic compounds introduces new properties to phages and could be a suitable strategy for construction of bio-inorganic carriers. In this review we try to cover the major phage species that have been used in drug and gene delivery systems, and the biological application of phages as novel targeting ligands and targeted therapeutics.

Cancer Microenvironment and Endoplasmic Reticulum Stress Response

Different stressful conditions such as hypoxia, nutrient deprivation, pH changes, or reduced vascularization, potentially able to act as growth-limiting factors for tumor cells, activate the unfolded protein response (UPR). UPR is therefore involved in tumor growth and adaptation to severe environments and is generally cytoprotective in cancer. The present review describes the molecular mechanisms underlying UPR and able to promote survival and proliferation in cancer. The critical role of UPR activation in tumor growth promotion is discussed in detail for a few paradigmatic tumors such as prostate cancer and melanoma.

KIAA1324 Suppresses Gastric Cancer Progression by Inhibiting the Oncoprotein GRP78

Recent advances in genome and transcriptome analysis have contributed to the identification of many potential cancer-related genes. Furthermore, biological and clinical investigations of the candidate genes provide us with a better understanding of carcinogenesis and development of cancer treatment. Here, we report a novel role of KIAA1324 as a tumor suppressor in gastric cancer. We observed that KIAA1324 was downregulated in most gastric cancers from transcriptome sequencing data and found that histone deacetylase was involved in the suppression of KIAA1324. Low KIAA1324 levels were associated with poor prognosis in gastric cancer patients. In the xenograft model, KIAA1324 significantly reduced tumor formation of gastric cancer cells and decreased development of preformed tumors. KIAA1324 also suppressed proliferation, invasion, and drug resistance and induced apoptosis in gastric cancer cells. Through protein interaction analysis, we identified GRP78 (glucose-regulated protein 78 kDa) as a KIAA1324-binding partner. KIAA1324 blocked oncogenic activities of GRP78 by inhibiting GRP78-caspase-7 interaction and suppressing GRP78-mediated AKT activation, thereby inducing apoptosis. In conclusion, our study reveals a tumor suppressive role of KIAA1324 via inhibition of GRP78 oncoprotein activities and provides new insight into the diagnosis and treatment of gastric cancer.

Vascular-targeted TNFα improves tumor blood vessel function and enhances antitumor immunity and chemotherapy in colorectal cancer

Delivery and penetration of chemotherapeutic drugs into neoplasm through the tumor vasculature are essential mechanisms to enhance the efficiency of chemotherapy. "Vascular targeting" strategy focuses on promoting the infiltration of chemotherapeutic drugs into neoplastic tissues. In this study, we achieved a targeted therapy by coupling tumor necrosis factor α (TNFα) with TCP-1, a novel vascular-targeting peptide, in an orthotopic colorectal cancer model in mice. High dose of TCP-1-conjugated TNFα (TCP-1/TNFα: 5μg/mouse) displayed potent antitumor activity by inducing apoptosis and reducing microvessel number in tumors than unconjugated TNFα, with no evidence of increased toxicity. In the combined therapy, the antitumor action of 5-fluorouracil (5-FU) was potentiated when the mice were pretreated with a low dose of TNFα (1ng/mouse) and to a greater extent by the same concentration of TCP-1/TNFα. In this regard, TCP-1/TNFα combined with 5-FU synergistically inhibited the tumor growth, induced apoptosis and reduced cell proliferation. More importantly, TCP-1/TNFα normalized the tumor vasculature and facilitated the infiltration of immune cells to neoplasm as well as attenuated the immunosuppressing effects of TNFα in bone marrow and spleen. At the same time, TCP-1/TNFα significantly improved 5-FU absorption into the tumor mass. Taken together, these findings underscore the therapeutic potential of TCP-1 as a drug carrier in cancer therapy. TCP-1 is a novel vascular-targeting peptide and appears to be a promising agent for drug delivery. TCP-1 fused with TNFα holds great promise for colorectal cancer therapy.

Mechanism study of peptide GMBP1 and its receptor GRP78 in modulating gastric cancer MDR by iTRAQ-based proteomic analysis

Background

Multidrug resistance (MDR) is a major obstacle to the treatment of gastric cancer (GC). Using a phage display approach, we previously obtained the peptide GMBP1, which specifically binds to the surface of MDR gastric cancer cells and is subsequently internalized. Furthermore, GMBP1 was shown to have the potential to reverse the MDR phenotype of gastric cancer cells, and GRP78 was identified as the receptor for this peptide. The present study aimed to investigate the mechanism of peptide GMBP1 and its receptor GRP78 in modulating gastric cancer MDR.

Methods

Fluorescence-activated cell sorting (FACS) and immunofluorescence staining were used to investigate the subcellular location and mechanism of GMBP1 internalization. iTRAQ was used to identify the MDR-associated downstream targets of GMBP1. Differentially expressed proteins were identified in GMBP1-treated compared to untreated SGC7901/ADR and SGC7901/VCR cells. GO and KEGG pathway analyses of the differentially expressed proteins revealed the interconnection of these proteins, the majority of which are involved in MDR. Two differentially expressed proteins were selected and validated by western blotting.

Results

GMBP1 and its receptor GRP78 were found to be localized in the cytoplasm of GC cells, and GRP78 can mediate the internalization of GMBP1 into MDR cells through the transferrin-related pathway. In total, 3,752 and 3,749 proteins were affected in GMBP1-treated SGC7901/ADR and SGC7901/VCR cells, respectively, involving 38 and 79 KEGG pathways. Two differentially expressed proteins, CTBP2 and EIF4E, were selected and validated by western blotting.

Conclusion

This study explored the role and downstream mechanism of GMBP1 in GC MDR, providing insight into the role of endoplasmic reticulum stress protein GRP78 in the MDR of cancer cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1361-3) contains supplementary material, which is available to authorized users.

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.

GRP78 promotes the invasion of pancreatic cancer cells by FAK and JNK

The major characteristics of pancreatic cancer are its excessive local invasion and early systemic dissemination. The glucose-regulated protein is over-expressed in many human cancers including pancreatic cancer and correlated with invasion and metastasis in many cancers. To investigate the effect of Grp78 on the invasion of pancreatic cancer, we used western blot and Transwell assay. We found Grp78 is expressed at lower levels in capan-2 and higher expressed in MiaPaCa-2 cells, and Grp78 expression levels were correlated with the invasion potentials of tumor cells. Then,we increased the expression of Grp78 in capan-2 cells and decreased the expression of Grp78 in MiaPaCa-2 cells. We found that over-expression of Grp78 caused significant increase in the expression of TIMP-1, TIMP-2, MMP-14, MMP-2, and MMP-9 in Capan-2 cells. Consistently, knockdown of Grp78 decreased the expression of them in MiaPaCa-2 cells. Gelatin zymography showed Grp78 over-expression stimulated the activities of MMP-2 and MMP-9, while GRP78 knockdown reduced the activities of MMP-2 and MMP-9. Cytoskeleton staining showed that knockdown of Grp78 caused a marked increase in cytoskeleton F-actin stress fibers in MiaPaCa-2 cells. Consistently, GRP78 knockdown hyperactivated RhoA and inhibited significantly Rac activity. Grp78 over-expression decreases the RhoA and stimulated Rac activity. We also found that Grp78 modulated FAK and JNK signaling pathways. Over-expression of GRP78 in Capan-2 activated FAK and JNK. Finally, we demonstrated that knockdown of FAK by shRNA in combination with blockade of JNK signaling pathway with SP600125 completely inhibited GRP78-induced cancer cell invasion. GRP78 is involved in the regulation of pancreatic cancer invasion. FAK and JNK are the key downstream effectors of GRP78.

Coronin3 regulates gastric cancer invasion and metastasis by interacting with Arp2

Coronin3 expression is increased in gastric cancer (GC) tissues and can promote GC invasion and metastasis. However, the mechanisms underlying Coronin3 function in GC remain unclear. In this study, we aimed to explore the interacting molecules essential for the tumor-promoting effects of Coronin3 in GC. Using mass spectrometric analysis, functional studies, and immunohistochemistry, we found that Arp2 interacted with Coronin3, and ectopic expression of Arp2 promoted GC cell migration and invasion, while Arp2 knockdown suppressed whole-cell motility and attenuated the Coronin3-mediated upregulation of cell migration and invasion. In addition, both proteins correlated with the metastatic status of GC patients. Furthermore, survival analyses demonstrated that both Coronin3 and Arp2 correlated with overall GC patient survival, and the combination of Coronin3 and Arp2 most accurately predicted GC patient prognosis. Combined, these data demonstrate that Coronin3 can regulate GC invasion and metastasis through Arp2, and the combination of Coronin3 and Arp2 provides a potential marker for predicting GC prognosis.

Peptide-based cancer therapy: opportunity and challenge

Cancer is one of the leading causes of death worldwide. Conventional cancer therapies mainly focus on mass cell killing without high specificity and often cause severe side effects and toxicities. Peptides are a novel class of anticancer agents that could specifically target cancer cells with lower toxicity to normal tissues, which will offer new opportunities for cancer prevention and treatment. Anticancer peptides face several therapeutic challenges. In this review, we present the sources and mechanisms of anticancer peptides and further discuss modification strategies to improve the anticancer effects of bioactive peptides.