Secreted AGR2 promotes invasion of colorectal cancer cells via Wnt11-mediated non-canonical Wnt signaling

AGR2-mediated unconventional secretion of 14-3-3ε and α-actinin-4, responsive to ER stress and autophagy, drives chemotaxis in canine mammary tumor cells

BACKGROUND

Canine mammary tumors (CMTs) in intact female dogs provide a natural model for investigating metastatic human cancers. Our prior research identified elevated expression of Anterior Gradient 2 (AGR2), a protein disulfide isomerase (PDI) primarily found in the endoplasmic reticulum (ER), in CMT tissues, highly associated with CMT progression. We further demonstrated that increased AGR2 expression actively influences the extracellular microenvironment, promoting chemotaxis in CMT cells. Unraveling the underlying mechanisms is crucial for assessing the potential of therapeutically targeting AGR2 as a strategy to inhibit a pro-metastatic microenvironment and impede tumor metastasis.

METHODS

To identify the AGR2-modulated secretome, we employed proteomics analysis of the conditioned media (CM) from two CMT cell lines ectopically expressing AGR2, compared with corresponding vector-expressing controls. AGR2-regulated release of 14-3-3ε (gene: YWHAE) and α-actinin 4 (gene: ACTN4) was validated through ectopic expression, knockdown, and knockout of the AGR2 gene in CMT cells. Extracellular vesicles derived from CMT cells were isolated using either differential ultracentrifugation or size exclusion chromatography. The roles of 14-3-3ε and α-actinin 4 in the chemotaxis driven by the AGR2-modulated CM were investigated through gene knockdown, antibody-mediated interference, and recombinant protein supplement. Furthermore, the clinical relevance of the release of 14-3-3ε and α-actinin 4 was assessed using CMT tissue-immersed saline and sera from CMT-afflicted dogs.

RESULTS

Proteomics analysis of the AGR2-modulated secretome revealed increased abundance in 14-3-3ε and α-actinin 4. Ectopic expression of AGR2 significantly increased the release of 14-3-3ε and α-actinin 4 in the CM. Conversely, knockdown or knockout of AGR2 expression remarkably reduced their release. Silencing 14-3-3ε or α-actinin 4 expression diminished the chemotaxis driven by AGR2-modulated CM. Furthermore, AGR2 controls the release of 14-3-3ε and α-actinin 4 primarily via non-vesicular routes, responding to the endoplasmic reticulum (ER) stress and autophagy activation. Knockout of AGR2 resulted in increased α-actinin 4 accumulation and impaired 14-3-3ε translocation in autophagosomes. Depletion of extracellular 14-3-3ε or α-actinin 4 reduced the chemotaxis driven by AGR2-modulated CM, whereas supplement with recombinant 14-3-3ε in the CM enhanced the CM-driven chemotaxis. Notably, elevated levels of 14-3-3ε or α-actinin 4 were observed in CMT tissue-immersed saline compared with paired non-tumor samples and in the sera of CMT dogs compared with healthy dogs.

CONCLUSION

This study elucidates AGR2's pivotal role in orchestrating unconventional secretion of 14-3-3ε and α-actinin 4 from CMT cells, thereby contributing to paracrine-mediated chemotaxis. The insight into the intricate interplay between AGR2-involved ER stress, autophagy, and unconventional secretion provides a foundation for refining strategies aimed at impeding metastasis in both canine mammary tumors and potentially human cancers.

BCL7B, a SWI/SNF complex subunit, orchestrates cancer immunity and stemness

Cancer is one of the main causes of human death. Here, we focus on the B-cell lymphoma 7 protein family member B (BCL7B) gene, an accessory subunit of the SWI/SNF chromatin-remodelling complex. To characterize the function of BCL7B, heterozygous BCL7B-deficient stomach cancer cell lines were generated with the CRISPR/Cas9 genome editing system. The comprehensive gene expression patterns were compared between parental cells and each ΔBCL7B cell line by RNA-seq. The results showed marked downregulation of immune-related genes and upregulation of stemness-related genes in the ΔBCL7B cell lines. Moreover, by ChIP-seq analysis with H3K27me3 antibody, the changes of epigenetic modification sequences were compared between parental cells and each ΔBCL7B cell line. After machine learning, we detected the centroid sequence changes, which exerted an impact on antigen presentation. The regulation of BCL7B expression in cancer cells gives rise to cancer stem cell-like characteristics and the acquisition of an immune evasion phenotype.

WNT5A: a double-edged sword in colorectal cancer progression

The Wnt signaling pathway is known to play a crucial role in cancer, and WNT5A is a member of this pathway that binds to the Frizzled (FZD) and Receptor Tyrosine Kinase-Like Orphan Receptor (ROR) family members to activate non-canonical Wnt signaling pathways. The WNT5A pathway is involved in various cellular processes, such as proliferation, differentiation, migration, adhesion, and polarization. In the case of colorectal cancer (CRC), abnormal activation or inhibition of WNT5A signaling can lead to both oncogenic and antitumor effects. Moreover, WNT5A is associated with inflammation, metastasis, and altered metabolism in cancer cells. This article aims to discuss the molecular mechanisms and dual roles of WNT5A in CRC.

LncRNA AFAP1-AS1 Induces Gefitinib Resistance of Lung Adenocarcinoma Through the miR-653-5p/AGR2 Axis

Purpose

Gefitinib resistance limits the therapeutic efficacy of gefitinib to lung adenocarcinoma (LUAD). The goal of this research is to learn more about the lncRNA AFAP1-AS1 and how it functions in gefitinib-resistant LUAD cells.

Methods

RT-qPCR was performed to test the expression of AFAP1-AS1, miR-653-5p and AGR2 in LUAD tissues with acquired resistance to gefitinib or not as well as in gefitinib-resistant LUAD cells. Cell proliferation, invasion and apoptosis were measured by CCK8 assays, transwell invasion assays and flow cytometry, respectively. Luciferase reporter assay showed that miR-653-5p and AFAP1-AS1 or AGR2 interactions.

Results

In gefitinib-resistant LUAD cells and tissues, AFAP1-AS1 was overexpressed. Meanwhile, silencing AFAP1-AS1 reduced proliferation and migration while increasing apoptosis and gefitinib sensitivity. Mechanically, AFAP1-AS1 sequestered the miR-653-5p and blocked the inhibition of miR-653-5p to AGR2 and stepwise upregulated AGR2 overexpression in LUAD gefitinib resistant cells, resulting gefitinib resistance in LUAD.

Conclusion

AFAP1-AS1 promotes gefitinib-resistance LUAD cells through a previously unrecognized miR-653-5p/AGR2 axis, suggesting targeting AFAP1-AS1/miR-653-5p/AGR2 axis might be a promising way for LUAD intervention.

Tumour-associated neutrophils secrete AGR2 to promote colorectal cancer metastasis via its receptor CD98hc-xCT

OBJECTIVE

Reciprocal cellular crosstalk within the tumour microenvironment (TME) actively participates in tumour progression. The anterior gradient-2 (AGR2) can be secreted to extracellular compartments and contribute to colorectal cancer (CRC) metastasis. We investigated the cellular source for secreted AGR2 in the TME and underlying mechanisms mediating secreted AGR2's effects.

DESIGN

Tissue microarray, tumour tissues, blood samples and tumour-associated neutrophils (TANs) from patients with CRC were isolated for phenotypical and functional analyses. The role of TAN-secreted AGR2 was determined in neutrophil-specific Agr2 knockout (Agr2^f/f;Mrp-Cre) mice. The biological roles and mechanisms of secreted AGR2 in CRC metastasis were determined in vitro and in vivo.

RESULTS

TANs were a predominant cell type for secreting AGR2 in the TME of CRC. TANs-secreted AGR2 promoted CRC cells' migration. Neutrophils-specific ablation of Agr2 in mice ameliorated CRC liver metastases. The heavy chain of CD98 (CD98hc) served as the functional receptor for secreted AGR2. Mechanistically, secreted AGR2 increased xCT activity in a CD98hc-dependent manner, subsequently activating Ras homologue family member A/Rho-associated protein kinase 2 cascade. CRC cells actively recruited TANs through the C-X-C motif chemokine 2. Moreover, CRC-derived transforming growth factor beta 1 (TGF-β1) educated peripheral blood neutrophils to become AGR2⁺ TANs that secrete AGR2. Abundant infiltration of AGR2⁺ TANs and high expression of TGF-β1 and CD98hc-xCT were correlated with poor prognosis of patients with CRC.

CONCLUSIONS

Our study unveils a novel crosstalk between TANs and CRC cells involving the secreted AGR2-CD98hc-xCT axis that promotes metastasis and impacts the outcomes of patients with CRC.

Anterior gradient proteins in gastrointestinal cancers: from cell biology to pathophysiology

Most of the organs of the digestive tract comprise secretory epithelia that require specialized molecular machines to achieve their functions. As such anterior gradient (AGR) proteins, which comprise AGR1, AGR2, and AGR3, belong to the protein disulfide isomerase family, and are involved in secretory and transmembrane protein biogenesis in the endoplasmic reticulum. They are generally expressed in epithelial cells with high levels in most of the digestive tract epithelia. To date, the vast majority of the reports concern AGR2, which has been shown to exhibit various subcellular localizations and exert pro-oncogenic functions. AGR2 overexpression has recently been associated with a poor prognosis in digestive cancers. AGR2 is also involved in epithelial homeostasis. Its deletion in mice results in severe diffuse gut inflammation, whereas in inflammatory bowel diseases, the secretion of AGR2 in the extracellular milieu participates in the reshaping of the cellular microenvironment. AGR2 thus plays a key role in inflammation and oncogenesis and may represent a therapeutic target of interest. In this review, we summarize the already known roles and mechanisms of action of the AGR family proteins in digestive diseases, their expression in the healthy digestive tract, and in digestive oncology. At last, we discuss the potential diagnostic and therapeutic implications underlying the biology of AGR proteins.

Functions and mechanisms of protein disulfide isomerase family in cancer emergence

The endoplasmic reticulum (ER) is a multi-layered organelle that is essential for the synthesis, folding, and structural maturation of almost one-third of the cellular proteome. It houses several resident proteins for these functions including the 21 members of the protein disulfide isomerase (PDI) family. The signature of proteins belonging to this family is the presence of the thioredoxin domain which mediates the formation, and rearrangement of disulfide bonds of substrate proteins in the ER. This process is crucial not only for the proper folding of ER substrates but also for maintaining a balanced ER proteostasis. The inclusion of new PDI members with a wide variety of structural determinants, size and enzymatic activity has brought additional epitomes of how PDI functions. Notably, some of them do not carry the thioredoxin domain and others have roles outside the ER. This also reflects that PDIs may have specialized functions and their functions are not limited within the ER. Large-scale expression datasets of human clinical samples have identified that the expression of PDI members is elevated in pathophysiological states like cancer. Subsequent functional interrogations using structural, molecular, cellular, and animal models suggest that some PDI members support the survival, progression, and metastasis of several cancer types. Herein, we review recent research advances on PDIs, vis-à-vis their expression, functions, and molecular mechanisms in supporting cancer growth with special emphasis on the anterior gradient (AGR) subfamily. Last, we posit the relevance and therapeutic strategies in targeting the PDIs in cancer.

Expression of hepatocyte nuclear factor 4 alpha, wingless-related integration site, and β-catenin in clinical gastric cancer

BACKGROUND

Gastric cancer (GC) is the second most common cause of cancer-related deaths worldwide. Hepatocyte nuclear factor 4 alpha (HNF4α) that belongs to the nuclear hormone receptor superfamily, is overexpressed in GC tissues, and might be involved in the development of GC by regulating its downstream wingless-related integration site (WNT)/β-catenin signaling.

AIM

To clarify the expression of HNF4α/WNT5a/β-catenin signaling proteins in clinical GC tissues.

METHODS

We immunohistochemically stained pathological blocks of GC and matched para-cancerous tissues. The intensity of HNF4α, WNT5a and β-catenin staining in the tumor cells was determined according to cell rates and staining intensity. The correlations between GC and HNF4α, WNT5a, and β-catenin expression using chi-square and paired chi-square tests. Relationships between double-positive HNF4α and WNT5a expression and types of gastric tumor tissues were assessed using regression analysis. Correlations between HNF4α and WNT5a expression at the RNA level in GC tissues found in the TCGA database were analyzed using Pearson correlation coefficients.

RESULTS

We found more abundant HNF4α and WNT5a proteins in GC, especially in mucinous adenocarcinoma and mixed GC than in adjacent tissues (P < 0.001). Low and high levels of cytoplasmic β-catenin respectively expressed in GC and adjacent tissues (P < 0.001) were not significantly associated with pathological parameters.

CONCLUSION

The expressions of HNF4α and WNT5a could serve as early diagnostic biomarkers for GC.

Wnt signaling in colorectal cancer: pathogenic role and therapeutic target

Background

The Wnt signaling pathway is a complex network of protein interactions that functions most commonly in embryonic development and cancer, but is also involved in normal physiological processes in adults. The canonical Wnt signaling pathway regulates cell pluripotency and determines the differentiation fate of cells during development. The canonical Wnt signaling pathway (also known as the Wnt/β-catenin signaling pathway) is a recognized driver of colon cancer and one of the most representative signaling pathways. As a functional effector molecule of Wnt signaling, the modification and degradation of β-catenin are key events in the Wnt signaling pathway and the development and progression of colon cancer. Therefore, the Wnt signaling pathway plays an important role in the pathogenesis of diseases, especially the pathogenesis of colorectal cancer (CRC).

Objective

Inhibit the Wnt signaling pathway to explore the therapeutic targets of colorectal cancer.

Methods

Based on studying the Wnt pathway, master the biochemical processes related to the Wnt pathway, and analyze the relevant targets when drugs or inhibitors act on the Wnt pathway, to clarify the medication ideas of drugs or inhibitors for the treatment of diseases, especially colorectal cancer.

Results

Wnt signaling pathways include: Wnt/β-catenin or canonical Wnt signaling pathway, planar cell polarity (Wnt-PCP) pathway and Wnt-Ca²⁺ signaling pathway. The Wnt signaling pathway is closely related to cancer cell proliferation, stemness, apoptosis, autophagy, metabolism, inflammation and immunization, microenvironment, resistance, ion channel, heterogeneity, EMT/migration/invasion/metastasis. Drugs/phytochemicals and molecular preparations for the Wnt pathway of CRC treatment have now been developed. Wnt inhibitors are also commonly used clinically for the treatment of CRC.

Conclusion

The development of drugs/phytochemicals and molecular inhibitors targeting the Wnt pathway can effectively treat colorectal cancer clinically.

Selective Secretion of KDEL-Bearing Proteins: Mechanisms and Functions

In multicellular organisms, cells must continuously exchange messages with the right meaning, intensity, and duration. Most of these messages are delivered through cognate interactions between membrane and secretory proteins. Their conformational maturation is assisted by a vast array of chaperones and enzymes, ensuring the fidelity of intercellular communication. These folding assistants reside in the early secretory compartment (ESC), a functional unit that encompasses endoplasmic reticulum (ER), intermediate compartment and cis-Golgi. Most soluble ESC residents have C-terminal KDEL-like motifs that prevent their transport beyond the Golgi. However, some accumulate in the ER, while others in downstream stations, implying different recycling rates. Moreover, it is now clear that cells can actively secrete certain ESC residents but not others. This essay discusses the physiology of their differential intracellular distribution, and the mechanisms that may ensure selectivity of release.

Therapeutic strategies targeting Wnt/β‑catenin signaling for colorectal cancer (Review)

Colorectal cancer (CRC) is one of the most common carcinomas. Although great progress has been made in recent years, CRC survival remains unsatisfactory due to high metastasis and recurrence. Understanding the underlying molecular mechanisms of CRC tumorigenesis and metastasis has become increasingly important. Recently, aberrant Wnt/β‑catenin signaling has been reported to be strongly associated with CRC tumorigenesis, metastasis and recurrence. Therefore, the Wnt/β‑catenin signaling pathway has potential value as a therapeutic target for CRC. In the present review, the dysregulation of this pathway in CRC and the promoting or suppressing function of therapeutic targets on CRC were explored. In addition, the interaction between this pathway and epithelial‑mesenchymal transition (EMT), cell stemness, mutations, metastasis‑related genes and tumor angiogenesis in CRC cells were also investigated. Numerous studies on this pathway may help identify the potential diagnostic and prognostic markers and therapeutic targets for CRC.

Porous Silicon-Based Aptasensors: Toward Cancer Protein Biomarker Detection

The anterior gradient homologue-2 (AGR2) protein is an attractive biomarker for various types of cancer. In pancreatic cancer, it is secreted to the pancreatic juice by premalignant lesions, which would be an ideal stage for diagnosis. Thus, designing assays for the sensitive detection of AGR2 would be highly valuable for the potential early diagnosis of pancreatic and other types of cancer. Herein, we present a biosensor for label-free AGR2 detection and investigate approaches for enhancing the aptasensor sensitivity by accelerating the target mass transfer rate and reducing the system noise. The biosensor is based on a nanostructured porous silicon thin film that is decorated with anti-AGR2 aptamers, where real-time monitoring of the reflectance changes enables the detection and quantification of AGR2, as well as the study of the diffusion and target-aptamer binding kinetics. The aptasensor is highly selective for AGR2 and can detect the protein in simulated pancreatic juice, where its concentration is outnumbered by orders of magnitude by numerous proteins. The aptasensor's analytical performance is characterized with a linear detection range of 0.05-2 mg mL^-1, an apparent dissociation constant of 21 ± 1 μM, and a limit of detection of 9.2 μg mL^-1 (0.2 μM), which is attributed to mass transfer limitations. To improve the latter, we applied different strategies to increase the diffusion flux to and within the nanostructure, such as the application of isotachophoresis for the preconcentration of AGR2 on the aptasensor, mixing, or integration with microchannels. By combining these approaches with a new signal processing technique that employs Morlet wavelet filtering and phase analysis, we achieve a limit of detection of 15 nM without compromising the biosensor's selectivity and specificity.

Serum Level of Tumor-Overexpressed AGR2 Is Significantly Associated with Unfavorable Prognosis of Canine Malignant Mammary Tumors

Simple Summary

Canine malignant mammary tumor (MMT) is a prevalent malignancy in intact female dogs. A current lack of easily accessible tumor biomarkers hinders a timely assessment of the disease outcome. This study reveals that anterior gradient protein 2 (AGR2) is overexpressed in canine MMT tissues, and elevated levels of extracellular AGR2 in sera of MMT dogs are significantly associated with progression and remote metastasis of MMT and an unfavorable overall survival of the patients. Hence, serum eAGR2 level is significantly associated with an adverse outcome of MMT dogs and holds a predictive potential in MMT prognosis.

Abstract

Canine malignant mammary tumors (MMTs) are prevalent malignancy in intact female dogs with a high incidence of metastasis and recurrence. A current lack of easily accessible tumor biomarkers hinders a timely assessment of the disease outcome. We previously identified anterior gradient protein 2 (AGR2) with higher protein abundance in canine MMT tissues compared with normal counterparts. AGR2 is an endoplasmic reticulum-resident protein disulfide isomerase involved in the regulation of protein processing and also exists extracellularly via secretion to exert pro-oncogenic functions. In the present study, we validated overexpression of AGR2 in canine MMT tissues from 45 dogs using immunohistochemistry and immunoblotting, and assessed serum AGR2 levels in 81 dogs with MMTs and 21 benign cases using a competitive enzyme-linked immunosorbent assay (ELISA). Our data revealed that serum eAGR2 levels are significantly correlated with MMT progression (p = 0.0007) and remote tumor metastasis (p = 0.002). Moreover, elevated levels of serum eAGR2 are associated with an unfavorable overall survival of MMT dogs in later stage (p = 0.0158). Area under the time-dependent ROC curve (AUC) of serum eAGR2 level as a prognostic indicator was 0.839. Collectively, this study uncovered that serum eAGR2 level is significantly associated with an adverse outcome of MMT dogs and holds a predictive potential in MMT prognosis.

Understanding the regulation of β-catenin expression and activity in colorectal cancer carcinogenesis: beyond destruction complex

Aberrant Wnt/β-catenin signaling is central to colorectal cancer carcinogenesis. The well-known potential of targeting the canonical Wnt signaling pathway for the treatment of CRC is largely attributed to the ability of this pathway to regulate various cellular processes such as cell proliferation, metastasis, drug resistance, immune response, apoptosis, and cellular metabolism. However, with the current approach of targeting this pathway, none of the Wnt-targeted agents have been successfully implicated in clinical practice. Instead of using classical approaches to target this pathway, there is a growing need to find new and modified approaches to achieve the same. For this, a better understanding of the regulation of β-catenin, a major effector of the canonical Wnt pathway is a must. The present review addresses the importance of understanding the regulation of β-catenin beyond the destruction complex. Few recently discovered β-catenin regulators such as ZNF281, TTPAL, AGR2, ARHGAP25, TREM2, and TIPE1 showed significant potential in regulating the development of CRC through modulation of the Wnt/β-catenin signaling pathway in both in vitro and in vivo studies. Although the expression and activity of β-catenin is influenced by many protein regulators, the abovementioned proteins not only influence its expression and activation but are also directly involved in the development of CRC and various other solid tumors. Therefore, we hypothesise that focusing the current research on finding the detailed mechanism of action of these regulators may assist in providing with a better treatment approach or improve the current therapeutic regimens.

AGR2 and AGR3 play an important role in the clinical characterization and prognosis of basal like breast cancer

INTRODUCTION

Basal-like Breast Cancer (BLBC) represents an important molecular subtype of breast cancer characterized by an aggressive behavior, molecular pathology poorly understood and a limited treatment.

OBJECTIVE

We aim to search for molecular differences between non-BLBC and BLBC tumors in order to propose possible diagnostic and prognostic biomarkers using databases. Metodology: Microarray processed data were downloaded from GEO database considering non-BLBC and BLBC. Enrichment analysis was evaluated using GO consortium and Ingenuity, protein-protein interaction, gene Ontology and co-expression analysis using STRING. Gene expression data was extracted using TCGA, METABRIC and Breast Cancer Gene-Expression Miner v4.2 databases. The Survival was evaluated using The Kaplan-Meier plotter.

RESULTS

Were identified 58 upregulated and 58 downregulated genes enriched in signaling pathways like PDGF, Angiogenesis, Integrin and WNT. AGR2 and AGR3 expression were reduced in BLBC in relation to non-BLBC tumors, patients aged ≤51 years, and with negativity of ER, PR and HER-2 and nodal status. Low expression of AGR2 and AGR3 were associated with worse OS and RFS for all breast cancer cases. But according to the molecular stratification, low AGR2 conferred worst OS in luminal A, worst RFS in BLBC and good OS and RFS in luminal B. High AGR3 conferred worse OS and RFS in BLBC, but low AGR3 attributed worse OS in luminal A.

CONCLUSION

AGR2 and AGR3 expression were able to differentiate non-BLBC from BLBC. Downregulation of AGR2 and AGR3 was associated with BLBC clinical phenotype. Furthermore, both genes behave different when considering prognosis and molecular stratification.

Protein disulfide isomerase inhibits endoplasmic reticulum stress response and apoptosis via its oxidoreductase activity in colorectal cancer

Protein disulfide isomerase (PDI), a principal endoplasmic reticulum resident oxidoreductase chaperone, is known to play a role in malignancies. This study aims to explore the molecular mechanism by which PDI regulates endoplasmic reticulum stress and the apoptosis signaling pathway in colorectal cancer (CRC). We determined the expression of PDI in CRC tissues and adjacent normal tissues. Gain- and loss- of function assays were conducted to evaluate the effects of PDI on oxidative stress, endoplasmic reticulum stress, and apoptosis in CRC cells, as reflected by hydrogen peroxide (H₂O₂) level and the expression of related proteins. PDI protein expression was upregulated in CRC tissues. Small molecule inhibitor of PDI or PDI knockdown reduced CRC cell viability and induced apoptosis. Overexpression of wild-type PDI augmented the viability of CRC cells and inhibited endoplasmic reticulum stress response and apoptosis. Small molecule inhibitor of PDI or PDI knockdown increased intracellular H₂O₂ level and activated apoptosis signaling pathway, which could be reversed by wild-type PDI restoration. Moreover, the catalytic active site of C-terminal of PDI was found to be indispensable for the regulatory effects of PDI on H₂O₂ levels, apoptosis and cell viability in CRC cells. Collectively, PDI inhibits endoplasmic reticulum stress and apoptosis of CRC cells through its oxidoreductase activity, thereby promoting the malignancy of CRC.

Intracellular AGR2 transduces PGE2 stimuli to promote epithelial-mesenchymal transition and metastasis of colorectal cancer

Human anterior gradient homolog 2 (AGR2) reportedly acts as an oncogene in multiple types of cancers. As a secreted protein, the oncogenic roles of extracellular AGR2 have been the focus of the increasing number of studies. In contrast, the oncological functions of intracellular AGR2 (iAGR2) remain elusive. Here, we report that intracellular AGR2 (iAGR2) is sufficient to promote CRC metastasis. iAGR2 binds to KDEL receptors (KDELRs) via its KTEL motif to activate downstream Gs-PKA signaling. Activated PKA upregulates the expression of NF-κB subunit c-Rel (REL) and acetylates histone H3 at lysine 9 (H3K9ac) to promote the transcription of SNAIL and SLUG. AGR2 can be upregulated by prostaglandin E2 (PGE2) via EP4-PI3K-AKT pathway and is indispensable for PGE2-induced CRC metastasis. AGR2 knockdown enhances therapeutic effects of a COX-2 inhibitor, celecoxib, in CRC metastasis. Collectively, our study reveals a promoting role and molecular mechanisms of iAGR2 in CRC metastasis and uncovers a new tumor microenvironment signal regulating AGR2 expression, which may provide new targets for treating metastatic CRC.

Anterior Gradient Protein 2 Promotes Mucosal Repair in Pediatric Ulcerative Colitis

Mucosal healing comprises a key goal of ulcerative colitis (UC) treatment. Anterior gradient protein 2 (AGR2) plays an important role in maintaining intestinal homeostasis in UC. However, the role of AGR2 in the repair of mucosal injury is not yet clear. This study is aimed at investigating the expression of AGR2 in the intestinal tissues of children with UC and its role in repairing mucosal injury. Forty UC patients who were hospitalized in the Pediatric Gastroenterology Ward of Shengjing Hospital affiliated with China Medical University between July 1, 2013, and May 31, 2020, and 20 children who had normal colonoscopy results during the same period (control group) made up the study sample. The disease activity of UC was evaluated based on the pediatric ulcerative colitis activity index, and the ulcerative colitis endoscopic index was evaluated according to the Rachmilewitz score. Immunohistochemical staining was employed to examine the differences in AGR2 expression in the intestinal mucosa between groups. The protective effect of AGR2 in a model of tumor necrosis factor-alpha- (TNF-α-) induced intestinal mucosal barrier injury and the underlying molecular mechanism were explored through in vitro experiments. The results showed that compared with the normal control group, UC patients in the remission or active period had significantly higher expression of AGR2 in the intestine. AGR2 expression was positively correlated with Ki67, an intestinal epithelial cell proliferation marker, but negatively correlated with the degree of endoscopic mucosal injury. In an in vitro model, AGR2 overexpression promoted cell proliferation and migration and inhibited TNF-α-induced intestinal epithelial barrier damage by activating yes-associated protein (YAP). Collectively, our study suggests that AGR2 might serve as a valuable biomarker to help assess the condition and mucosal healing status of UC patients. In vitro, AGR2 promoted the repair of intestinal mucosal barrier injury by activating YAP.

Long non-coding RNA-H19 promotes ovarian cancer cell proliferation and migration via the microRNA-140/Wnt1 axis

To explore the effect and underlying molecular mechanism of long non-coding RNA (lncRNA)-H19 on ovarian cancer (OC) cells, a total of 41 cases of OC and adjacent normal tissues were collected. H19 and microRNA (miR)-140 expressions in OC tissues and cells were detected using quantitative real-time polymerase chain reaction (qRT-RCR). The correlation between H19 expression and prognosis of OC patient was analyzed. siRNA (si)-H19 and si-negative control (NC) were transfected into OC cells. Cell proliferation was checked by cell counting kit-8 assay and colony formation assay, and cell migration and invasion were analyzed via Transwell assay. The targeted binding relationship between H19 and miR-140 was predicted and verified, miR-140 downstream gene was predicted and Wnt1 was screened out. The impact of in-miR-140 on the si-H19-induced decreased OC cell proliferation and migration was evaluated. H19 expression was upregulated in OC tissues and cells, and its overexpression was associated with a poor prognosis of OC. si-H19 remarkably reduced OC cell proliferation and migration. H19 upregulated Wnt1 expression through targeting miR-140 in OC cells. Altogether, miR-140 was notably downregulated in OC, and in-miR-140 partially inhibited the si-H19-induced decrease of OC cell proliferation and migration. H19 competitively bound to miR-140 to upregulate Wnt1, thereby promoting OC cell proliferation and migration.

Effects of ER-resident and secreted AGR2 on cell proliferation, migration, invasion, and survival in PANC-1 pancreatic cancer cells

Background

Anterior gradient-2 (AGR2) is a proto-oncogene involved in tumorigenesis and cancer progression. AGR2, predominantly localized in the endoplasmic reticulum (ER), is also a secreted protein detected in the extracellular compartment in multiple cancers. However, the biological functions of intracellular and extracellular AGR2 remain to be elucidated.

Methods

Based on the biochemical structure of AGR2 protein, PANC-1 pancreatic cancer cells stably expressing ER-resident or secreted AGR2 were generated by a lentivirus-mediated stable overexpression system. The capacities of cell proliferation, migration, invasion and survival were assessed in PANC-1 stable cells. Moreover, EGFR expression and activation were determined to explore the possible mechanism of AGR2 roles in pancreatic cancer tumorigenesis.

Results

It was discovered that secreted AGR2, but not ER-resident AGR2, promotes cell proliferation, migration and invasion of PANC-1 cells. Moreover, the data indicated that both the ER-resident and the secreted AGR2 enhance the survival capacity of PANC-1 cells after tunicamycin-induced ER stress and gemcitabine treatment. However, EGFR expression and activation were not found to be involved in AGR2-dependent oncogenic phenotypes in PANC-1 cells.

Conclusions

Secreted AGR2 is predominantly involved in cell proliferation, migration and invasion in PANC-1 pancreatic cancer cells. Both secreted and ER-resident AGR2 contribute to the survival of PANC-1 cells under the challenging conditions. These findings provide insight into how different localizations of AGR2 have contributed to pancreatic cancer growth, metastasis, and drug sensitivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07743-y.

Wnt/β‑catenin signaling: Causes and treatment targets of drug resistance in colorectal cancer (Review)

Colorectal cancer (CRC) is the third most common malignant tumor in humans. Chemotherapy is used for the treatment of CRC. However, the effect of chemotherapy remains unsatisfactory due to drug resistance. Growing evidence has shown that the presence of highly metastatic tumor stem cells, regulation of non-coding RNAs and the tumor microenvironment contributes to drug resistance mechanisms in CRC. Wnt/β-catenin signaling mediates the chemoresistance of CRC in these three aspects. Therefore, the present study analyzed the abundant evidence of the contribution of Wnt/β-catenin signaling to the development of drug resistance in CRC and discussed its possible role in improving the chemosensitivity of CRC, which may provide guidelines for its clinical treatment.

The involvement of noncanonical Wnt signaling in cancers

Wnt signaling is one of the key cascades regulating normal tissue development and has been tightly associated with cancer. The Wnt signaling can be subdivided into two categories: canonical & noncanonical. Noncanonical Wnt signaling pathways mainly include Wnt/PCP (planar cell polarity) signaling and Wnt-cGMP (cyclic guanosine monophosphate) /Ca2+ signaling. It has been well studied by previous researches that noncanonical Wnt signaling regulates multiple cell functions including proliferation, differentiation, adhesion, polarity, motility, and migration. The aberrant activation or inhibition of noncanonical Wnt signaling is crucial in cancer progression, exerting both oncogenic and tumor-suppressive effects. Recent studies show the involvement of noncanonical Wnt in regulating cancer cell invasion, metastasis, metabolism, and inflammation. Here, we review current insights into novel components of non-canonical signalings and describe their involvement in various cancer types. We also summarize recent biological and clinical discoveries that outline non-canonical Wnt signaling in tumorigenesis. Finally, we provide an overview of current strategies to target non-canonical Wnt signaling in cancer and challenges that are associated with such approaches.

Secretion of pro-oncogenic AGR2 protein in cancer

Anterior gradient-2 (AGR2) protein mediates the formation, breakage and isomerization of disulphide bonds during protein maturation in the endoplasmic reticulum (ER) and contributes to the homoeostasis of the secretory pathway. AGR2 promotes tumour development and metastasis and its elevated expression is almost completely restricted to malignant tumours. Interestingly, this supposedly ER-resident protein can be localised to other compartments of cancer cells and can also be secreted into the extracellular milieu. There are emerging evidences that describe the gain-of-function activities of the extracellular AGR2, particularly in cancer development. Here, we reviewed studies detailing the expression, pathological and physiological roles associated with AGR2 and compared the duality of localization, intracellular and extracellular, with special emphasis on the later. We also discussed the possible mechanisms of AGR2 secretion as well as deliberating the functional impacts of AGR2 in cancer settings. Last, we deliberate the current therapeutic strategies and posit the potential use AGR2, as a prognosis and diagnosis marker in cancer.

Identification of EMT-related high-risk stage II colorectal cancer and characterisation of metastasis-related genes

Background

Our laboratory previously reported an individual-level prognostic signature for patients with stage II colorectal cancer (CRC). However, this signature was not applicable for RNA-sequencing datasets. In this study, we constructed a robust epithelial-to-mesenchymal transition (EMT)- related gene pair prognostic signature.

Methods

Based on EMT-related genes, metastasis-associated gene pairs were identified between metastatic and non-metastatic samples. Then, we selected prognosis-associated gene pairs, which were significantly correlated with disease-free survival of stage II CRC using multivariate Cox regression model, as the EMT-related prognosis signature.

Results

An EMT-related signature composed of fifty-one gene pairs (51-GPS) for prediction-relapse risk of patients with stage II CRC was developed, whose prognostic efficiency was validated in independent datasets. Moreover, 51-GPS achieved better predictive performance than other reported signatures, including a commercial signature Oncotype Dx colon cancer and an immune-related gene pair signature. Besides, EMT-related functional gene sets achieved high enrichment scores in high-risk samples. Especially, loss-of-function antisense approach showed that DEGs between the predicted two clusters were metastasis-related.

Conclusions

The EMT-related gene pair signature can identify the high relapse-risk patients with stage II CRC, which can facilitate individualised management of patients.

The Role of Calmodulin in Tumor Cell Migration, Invasiveness, and Metastasis

Calmodulin (CaM) is the principal Ca²⁺ sensor protein in all eukaryotic cells, that upon binding to target proteins transduces signals encoded by global or subcellular-specific changes of Ca²⁺ concentration within the cell. The Ca²⁺/CaM complex as well as Ca²⁺-free CaM modulate the activity of a vast number of enzymes, channels, signaling, adaptor and structural proteins, and hence the functionality of implicated signaling pathways, which control multiple cellular functions. A basic and important cellular function controlled by CaM in various ways is cell motility. Here we discuss the role of CaM-dependent systems involved in cell migration, tumor cell invasiveness, and metastasis development. Emphasis is given to phosphorylation/dephosphorylation events catalyzed by myosin light-chain kinase, CaM-dependent kinase-II, as well as other CaM-dependent kinases, and the CaM-dependent phosphatase calcineurin. In addition, the role of the CaM-regulated small GTPases Rac1 and Cdc42 (cell division cycle protein 42) as well as CaM-binding adaptor/scaffold proteins such as Grb7 (growth factor receptor bound protein 7), IQGAP (IQ motif containing GTPase activating protein) and AKAP12 (A kinase anchoring protein 12) will be reviewed. CaM-regulated mechanisms in cancer cells responsible for their greater migratory capacity compared to non-malignant cells, invasion of adjacent normal tissues and their systemic dissemination will be discussed, including closely linked processes such as the epithelial–mesenchymal transition and the activation of metalloproteases. This review covers as well the role of CaM in establishing metastatic foci in distant organs. Finally, the use of CaM antagonists and other blocking techniques to downregulate CaM-dependent systems aimed at preventing cancer cell invasiveness and metastasis development will be outlined.

The anterior gradient-2 interactome

The anterior gradient-2 (AGR2) is an endoplasmic reticulum (ER)-resident protein belonging to the protein disulfide isomerase family that mediates the formation of disulfide bonds and assists the protein quality control in the ER. In addition to its role in proteostasis, extracellular AGR2 is responsible for various cellular effects in many types of cancer, including cell proliferation, survival, and metastasis. Various OMICs approaches have been used to identify AGR2 binding partners and to investigate the functions of AGR2 in the ER and outside the cell. Emerging data showed that AGR2 exists not only as monomer, but it can also form homodimeric structure and thus interact with different partners, yielding different biological outcomes. In this review, we summarize the AGR2 “interactome” and discuss the pathological and physiological role of such AGR2 interactions.

LINC02273 drives breast cancer metastasis by epigenetically increasing AGR2 transcription

BACKGROUND

The majority of breast cancer patients die of metastasis rather than primary tumors, whereas the molecular mechanisms orchestrating cancer metastasis remains poorly understood. Long noncoding RNAs (lncRNA) have been shown to regulate cancer occurrence and progression. However, the lncRNAs that drive metastasis in cancer patients and their underlying mechanisms are still largely unknown.

METHODS

lncRNAs highly expressed in metastatic lymph nodes were identified by microarray. Survival analysis were made by Kaplan-Meier method. Cell proliferation, migration, and invasion assay was performed to confirm the phenotype of LINC02273. Tail vein model and mammary fat pad model were used for in vivo study. RNA pull-down and RIP assay were used to confirm the interaction of hnRNPL and LINC02273. Chromatin isolation by RNA purification followed by sequencing (ChIRP-seq), RNA-seq, ChIP-seq, and luciferase reporter assay reveal hnRNPL-LINC02273 regulates AGR2. Antisense oligonucleotides were used for in vivo treatment.

RESULTS

We identified a novel long noncoding RNA LINC02273, whose expression was significantly elevated in metastatic lesions compared to the primary tumors, by genetic screen of matched tumor samples. Increased LINC02273 promoted breast cancer metastasis in vitro and in vivo. We further showed that LINC02273 was stabilized by hnRNPL, a protein increased in metastatic lesions, in breast cancer cells. Mechanistically, hnRNPL-LINC02273 formed a complex which activated AGR2 transcription and promoted cancer metastasis. The recruitment of hnRNPL-LINC02273 complex to AGR2 promoter region epigenetically upregulated AGR2 by augmenting local H3K4me3 and H3K27ac levels. Combination of AGR2 and LINC02273 was an independent prognostic factor for predicting breast cancer patient survival. Moreover, our data revealed that LINC02273-targeting antisense oligonucleotides (ASO) substantially inhibited breast cancer metastasis in vivo.

CONCLUSIONS

Our findings uncover a key role of LINC02273-hnRNPL-AGR2 axis in breast cancer metastasis and provide potential novel therapeutic targets for metastatic breast cancer intervention.

AGR3 promotes the stemness of colorectal cancer via modulating Wnt/β-catenin signalling

Cancer cells with stem cell properties have been acknowledged to be responsible for cancer initiation and progression. Wnt/β-catenin signalling is a major signal pathway promoting the stemness of cancer cells. Anterior gradient 3 (AGR3), a member of the protein disulfide isomerase (PDI) family, was found to be overexpressed in several cancers. However, the roles and mechanisms of AGR3 in colorectal cancer (CRC) have not been previously described. In our study, we find that AGR3 is highly expressed in CRC and associated with poor prognosis. Functional studies show that AGR3 promotes the stemness of CRC cells. Mechanically, AGR3 activates Wnt/β-catenin signalling and promotes the nuclear translocation of β-catenin to upregulate stemness related genes. Wnt/β-catenin signalling inhibition counteracts the promoting effect of AGR3 on cancer stemness. Moreover, the effect of AGR3 on Wnt/β-catenin signalling and cancer stemness depends on the presence of frizzled 4 (FZD4). Thus, our study first uncovers the stemness-promoting role and the oncogenic mechanism of AGR3 in CRC, which might provide a novel target for designing anti-CRC strategies.

Extracellular AGR3 regulates breast cancer cells migration via Src signaling

Human anterior gradient proteins AGR2 and AGR3 are overexpressed in a variety of adenocarcinomas and are often secreted in cancer patients' specimens, which suggests a role for AGR proteins in intra and extracellular compartments. Although these proteins exhibit high sequence homology, AGR2 is predominantly described as a pro-oncogene and a potential prognostic biomarker. However, little is known about the function of AGR3. Therefore, the aim of the present study was to investigate the role of AGR3 in breast cancer. The results demonstrated that breast cancer cells secrete AGR3. Furthermore, it was revealed that extracellular AGR3 (eAGR3) regulates tumor cell adhesion and migration. The current study indicated that the pharmacological and genetic perturbation of Src kinase signaling, through treatment with Dasatinib (protein kinase inhibitor) or investigating cells that express a dominant-negative form of Src, significantly abrogated eAGR3-mediated breast cancer cell migration. Therefore, the results indicated that eAGR3 may control tumor cell migration via activation of Src kinases. The results of the present study indicated that eAGR3 may serve as a microenvironmental signaling molecule in tumor-associated processes.

AGR2 silencing contributes to metformin-dependent sensitization of colorectal cancer cells to chemotherapy

There is growing epidemiological evidence indicating an association between diabetes mellitus and the increased incidence of colorectal cancer (CRC). The preferred initial and most widely used pharmacological agent for the treatment of type 2 diabetes is metformin, which in parallel reduces the risk of CRC and improves patient prognosis. AMP-activated protein kinase (AMPK) appears to be tightly associated with the beneficial metabolic effects of metformin, serving as a cellular energy sensor activated in response to a variety of conditions that deplete cellular energy levels. Such conditions include nutrient starvation (particularly glucose), hypoxia and exposure to toxins that inhibit the mitochondrial respiratory chain complex. The aim of the present study was to determine the effect of metformin on CRC cell lines, with different levels of anterior gradient 2 (AGR2) expression, exposed to 5-fluorouracil (5-FU) and oxaliplatin, alone or in combination with metformin. AGR2 has recently emerged as a factor involved in colon carcinogenesis. In AGR2-knockout cells, markedly higher levels of phosphorylated-AMPK were observed in comparison with control cells transfected with GFP-scrambled guide RNA, which indicated that the presence of AGR2 may interfere with the metformin-dependent activation of AMPK. In addition, metformin in combination with 5-FU and oxaliplatin induced ROS production and attenuated autophagy. This effect was enhanced in AGR2-knockout cells.

Long non-coding RNA LINC01207 silencing suppresses AGR2 expression to facilitate autophagy and apoptosis of pancreatic cancer cells by sponging miR-143-5p

Pancreatic cancer is a serious malignancy accompanied by a well-documented poor prognosis. Accumulating studies have indicated the crucial roles played by long non-coding RNAs (lncRNAs) in proliferation, apoptosis and invasion of cancer cells. The aim of the current study was to investigate the role of lncRNA LINC01207 in autophagy and apoptosis of pancreatic cancer cells and its regulatory mechanism interacting with miR-143-5p. Initially, expression profiles of lncRNAs and genes associated with pancreatic cancer were identified. The expression patterns of LINC01207, miR-143-5p and AGR2 in both pancreatic cancer and adjacent tissues were then determined. The binding relationship of LINC01207 to miR-143-5p and targeting relationship of miR-143-5p to AGR2 were subsequently verified. Silencing of LINC01207, or up-regulation or down-regulation of miR-143-5p was introduced into the pancreatic cancer cells, so as to analyze their effects on the cell growth, apoptosis and autophagy. Besides, these regulatory effects were further explored with the determination of the autophagy- and apoptosis-related gene or proteins. LINC01207 and AGR2 were highly expressed while miR-143-5p was poorly expressed in pancreatic cancer. Functionally, LINC01207 can bind to miR-143-5p, and AGR2 was a target gene of miR-143-5p. Importantly, silencing of LINC01207 down-regulated the expression of AGR2 by up-regulating miR-143-5p. Moreover, silencing of LINC01207 and up-regulation of miR-143-5p promoted cell apoptosis and autophagy, corresponding to increased expression of autophagy- and apoptosis-related proteins, in addition to inhibited cell growth. Taken together, silencing of LINC01207 prevents the progression of pancreatic cancer by impairing miR-143-5p-targeted AGR2 expression, providing a potential target for pancreatic cancer treatment.

A Complex Role for Calcium Signaling in Colorectal Cancer Development and Progression

Clinical data suggest that many malignant cancers are associated with hypercalcemia. Hypercalcemia can facilitate the proliferation and metastasis of gastric and colon tumors, and has been considered a hallmark of end-stage disease. However, it has also been reported that dietary calcium or vitamin D supplementation could reduce the risk of many types of cancers. In particular, the intestines can absorb considerable amounts of calcium via Ca²⁺-permeable ion channels, and hypercalcemia is common in patients with colorectal cancer. Thus, this review considers the role of calcium signaling in the context of colorectal cancer and summarizes the functions of specific regulators of cellular calcium levels in the proliferation, invasion, metastasis, cell death, and drug resistance of colorectal cancer cells. The data reveal that even a slight upregulation of intracellular Ca²⁺ signaling can facilitate the onset and progression of colorectal cancer, while continuous Ca²⁺ influx and Ca²⁺ overload may cause tumor cell death. This dual function of Ca²⁺ signaling adds nuance to the debate over the hallmarks of colorectal cancer, and may even provide new directions and strategies for clinical interventions.

Evolutionary Origin and Nomenclature of Vertebrate Wnt11-Family Genes

To adequately connect zebrafish medical models to human biology, it is essential that gene nomenclature reflects gene orthology. Analysis of gene phylogenies and conserved syntenies shows that the zebrafish gene currently called wnt11 (ENSDARG00000004256, ZFIN ID: ZDB-GENE-990603-12) is not the ortholog of the human gene called WNT11 (ENSG00000085741); instead, the gene currently called wnt11r (ENSDARG00000014796, ZFIN ID: ZDB-GENE-980526-249) is the zebrafish ortholog of human WNT11. Genomic analysis of Wnt11-family genes suggests a model for the birth of Wnt11-family gene ohnologs in genome duplication events, provides a mechanism for the death of a Wnt11-family ohnolog in mammals after they diverged from birds, and suggests revised nomenclature to better connect teleost disease models to human biology.

Wnt-11 as a Potential Prognostic Biomarker and Therapeutic Target in Colorectal Cancer

The expression of the secreted factor Wnt-11 is elevated in several types of cancer, including colorectal cancer, where it promotes cancer cell migration and invasion. Analysis of colorectal cancer gene expression databases associated WNT11 mRNA expression with increased likelihood of metastasis in a subset of patients. WNT11 expression was correlated with the expression of the Wnt receptors FZD6, RYK, and PTK7, and the combined expression of WNT11, FZD6 and RYK or PTK7 was associated with an increased risk of 5-year mortality rates. Immunohistochemical analysis of Wnt-11 in a cohort of 357 colorectal cancer patients found significantly higher Wnt-11 levels in tumors, compared with benign tissue. Elevated Wnt-11 levels occurred more frequently in rectal tumors than in colonic tumors and in tumors from women than men. In univariate analysis, increased Wnt-11 expression was also associated with tumor invasion and increased 5-year mortality. High Wnt-11 levels were not associated with high levels of nuclear β-catenin, suggesting Wnt-11 is not simply an indicator for activation of β-catenin-dependent signaling. Expression of Wnt-11 in colorectal cancer cell lines expressing low endogenous Wnt-11 inhibited β-catenin/Tcf activity and increased ATF2-dependent transcriptional activity. WNT11 gene silencing and antibody-mediated inhibition of Wnt-11 in colorectal cancer cell lines expressing high Wnt-11 reduced their capacity for invasion. Together, these observations suggest that Wnt-11 could be a potential target for the treatment of patients with invasive colorectal cancer.

Basic helix-loop-helix transcription factor Twist1 is a novel regulator of anterior gradient protein 2 homolog (AGR2) in breast cancer

Anterior gradient protein 2 homolog (AGR2) belongs to the disulfide isomerase family of endoplasmic reticulum proteins. Itis overexpressed in several types of solid tumors, including tumors of the prostate, lung, and pancreas. However, the role of AGR2 in breast cancer and the regulatory mechanisms underlying AGR2 protein expressionare not fullyunderstood. We demonstrated that AGR2 levels are increased under hypoxic conditions and in breast cancer tumors. Mechanistically, Twist1 binds to, and activates the AGR2 promoter via an E-box sequence. Under hypoxic conditions, the increased expression of ARG2 is attenuated when Twist1 levels are reduced by shRNA. Conversely, Twist1 overexpression fully reverses decreased AGR2 levels upon HIF-1α knockdown. Notably, AGR2 is required for Twist1-induced proliferation, migration, and invasion of breast cancer cells. Collectively, these findings extend our understanding of AGR2 regulation in breast cancer and may contribute to development of Twist1-AGR2 targeting therapeutics for breast cancer.

Anterior Gradient-2 monoclonal antibody inhibits lung cancer growth and metastasis by upregulating p53 pathway and without exerting any toxicological effects: A preclinical study

Increased drug resistance and acute side effects on normal organs are the major disadvantages of traditional cancer chemotherapy and radiotherapy. This has increased the focus on targeted therapeutic strategies such as monoclonal antibody-based cancer therapies. The major advantage of antibody-based therapies is the specific inhibition of cancer-related targets, with reduced off-target side effects. Anterior gradient-2 (AGR2) is a prometastatic and proangiogenic tumor marker that is overexpressed in multiple cancers. Therefore, anti-AGR2 antibodies may be potential therapeutic agents for treating different cancers. In the present study, we examined a novel anti-AGR2 monoclonal antibody mAb18A4 and found that this antibody inhibited lung cancer progression and metastasis without exerting any adverse side effects on the major organs and blood in mice. Moreover, we found that mAb18A4 activated p53 pathway and attenuated ERK1/2-MAPK pathway. Furthermore, mAb18A4-treated cancer cell lines showed attenuated proliferation and colony formation, enhanced apoptosis, increased p53 expression, and reduced phosphorylated ERK1/2 expression. Treatment with mAb18A4 significantly reduced tumor size and suppressed tumor metastasis in and increased the survival of different xenograft tumor models. In addition, mAb18A4 potently suppressed AGR2-induced angiogenesis. Results of pharmacokinetic and toxicological analyses confirmed the safety of mAb18A4 as an antitumor treatment.

Loss of ER retention motif of AGR2 can impact mTORC signaling and promote cancer metastasis

Anterior gradient 2 (AGR2) is a member of the protein disulfide isomerase (PDI) family, which plays a role in the regulation of protein homeostasis and the unfolded protein response pathway (UPR). AGR2 has also been characterized as a proto-oncogene and a potential cancer biomarker. Cellular localization of AGR2 is emerging as a key component for understanding the role of AGR2 as a proto-oncogene. Here, we provide evidence that extracellular AGR2 (eAGR2) promotes tumor metastasis in various in vivo models. To further characterize the role of the intracellular-resident versus extracellular protein, we performed a comprehensive protein-protein interaction screen. Based on these results, we identify AGR2 as an interacting partner of the mTORC2 pathway. Importantly, our data indicates that eAGR2 promotes increased phosphorylation of RICTOR (T1135), while intracellular AGR2 (iAGR2) antagonizes its levels and phosphorylation. Localization of AGR2 also has opposing effects on the Hippo pathway, spheroid formation, and response to chemotherapy in vitro. Collectively, our results identify disparate phenotypes predicated on AGR2 localization. Our findings also provide credence for screening of eAGR2 to guide therapeutic decisions.