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Human anterior gradient‐2 (AGR2) has been implicated in carcinogenesis of various solid tumours, but the expression data in prostate cancer are contradictory regarding its prognostic value. The objective of this study is to evaluate the expression of AGR2 in a large prostate cancer cohort and to correlate it with clinicopathological data. AGR2 protein expression was analysed immunohistochemically in 1023 well‐characterized prostate cancer samples with a validated antibody. AGR2 expression levels in carcinomas were compared with matched tissue samples of adjacent normal glands. AGR2 expression levels were dichotomized and tested for statistical significance. Increased AGR2 expression was found in 93.5% of prostate cancer cases. AGR2 levels were significantly higher in prostate cancer compared with normal prostate tissue. A gradual loss of AGR2 expression was associated with increasing tumour grade (ISUP), and AGR2 expression is inversely related to patient survival, however, multivariable significance is not achieved. AGR2 is clearly upregulated in the majority of prostate cancer cases, yet a true diagnostic value appears unlikely. In spite of the negative correlation of AGR2 expression with increasing tumour grade, no independent prognostic significance was found in this large‐scale study. [ABSTRACT FROM AUTHOR]

Intestinal goblet cells are secretory cells specialized in the production of mucins, and as such are challenged by the need for efficient protein folding. Goblet cells express Inositol-Requiring Enzyme-1β (IRE1β), a unique sensor in the unfolded protein response (UPR), which is part of an adaptive mechanism that regulates the demands of mucin production and secretion. However, how IRE1β activity is tuned to mucus folding load remains unknown. We identified the disulfide isomerase and mucin chaperone AGR2 as a goblet cell-specific protein that crucially regulates IRE1β-, but not IRE1α-mediated signaling. AGR2 binding to IRE1β disrupts IRE1β oligomerization, thereby blocking its downstream endonuclease activity. Depletion of endogenous AGR2 from goblet cells induces spontaneous IRE1β activation, suggesting that alterations in AGR2 availability in the endoplasmic reticulum set the threshold for IRE1β activation. We found that AGR2 mutants lacking their catalytic cysteine, or displaying the disease-associated mutation H117Y, were no longer able to dampen IRE1β activity. Collectively, these results demonstrate that AGR2 is a central chaperone regulating the goblet cell UPR by acting as a rheostat of IRE1β endonuclease activity. Synopsis: IRE1β is specifically expressed in mucin-secreting goblet cells of the mammalian gut. Here, the mucin chaperone AGR2 is identified as master regulator of IRE1β oligomerization and endonuclease activity. The protein disulfide isomerase AGR2 acts as a specific interactor of the unfolded protein response sensor IRE1β in colon epithelial cells. AGR2 inhibits IRE1β endonuclease activity by promoting IRE1β monomerization. The inflammatory bowel disease-associated AGR2H117Y mutant loses its repressive activity on IRE1β. AGR2 regulates IRE1β UPR sensor activity by holding it in a monomeric inactive state. [ABSTRACT FROM AUTHOR]

Epithelial‐mesenchymal transition (EMT) is associated with tumorigenesis and drug resistance. The Rab superfamily of small G‐proteins plays a role in regulating cell cytoskeleton and vesicle transport. However, it is not yet clear how the Rab family contributes to cancer progression by participating in EMT. By analysing various in silico datasets, we identified a statistically significant increase in RAB31 expression in the oxaliplatin‐resistant group compared to that in the parental or other chemotherapy drug groups. Our findings highlight RAB31's powerful effect on colorectal cancer cell lines when compared with other family members. In a study that analysed multiple online meta‐databases, RAB31 RNA levels were continually detected in colorectal tissue arrays. Additionally, RAB31 protein levels were correlated with various clinical parameters in clinical databases and were associated with negative prognoses for patients. RAB31 expression levels in all three probes were calculated using a computer algorithm and were found to be positively correlated with EMT scores. The expression of the epithelial‐type marker CDH1 was suppressed in RAB31 overexpression models, whereas the expression of the mesenchymal‐type markers SNAI1 and SNAI2 increased. Notably, RAB31‐induced EMT and drug resistance are dependent on extracellular vesicle (EV) secretion. Interactome analysis confirmed that RAB31/AGR2 axis‐mediated exocytosis was responsible for maintaining colorectal cell resistance to oxaliplatin. Our study concluded that RAB31 alters the sensitivity of oxaliplatin, a supplementary chemotherapy approach, and is an independent prognostic factor that can be used in the treatment of colorectal cancer. [ABSTRACT FROM AUTHOR]

Background: The prognostic role of either forkhead box A1 (FOXA1) or anterior gradient 2 (AGR2) in breast cancer has been found separately. Considering that there were interplays between them depending on ER status, we aimed to assess the statistical interaction between AGR2 and FOXA1 on breast cancer prognosis and examine the prognostic role of the combination of them by ER status. Methods: AGR2 and FOXA1 expression in tumor tissues were evaluated with tissue microarrays by immunohistochemistry in 915 breast cancer patients with follow up data. The expression levels of these two markers were treated as binary variables, and many different cutoff values were tried for each marker. Survival and Cox proportional hazard analyses were used to evaluate the relationship between AGR2, FOXA1 and prognosis, and the statistical interaction between them on the prognosis was assessed on multiplicative scale. Results: Statistical interaction between AGR2 and FOXA1 on the PFS was significant with all the cutoff points in ER-positive breast cancer patients but not ER-negative ones. Among ER-positive patients, the poor prognostic role of the high level of FOXA1 was significant only in patients with the low level of AGR2, and vice versa. When AGR2 and FOXA1 were considered together, patients with low levels of both markers had significantly longer PFS compared with all other groups. Conclusions: There was a statistical interaction between AGR2 and FOXA1 on the prognosis of ER-positive breast cancer. The combination of AGR2 and FOXA1 was a more useful marker for the prognosis of ER-positive breast cancer patients. [ABSTRACT FROM AUTHOR]

Epithelium‐specific ETS transcription factor 1 (ESE1) has been implicated in epithelial homeostasis, inflammation, as well as tumorigenesis, and cancer progression. However, numerous studies have reported contradictory roles—as an oncogene or a tumor suppressor of ESE1 in different cancers, and its function in the development and progression of pancreatic ductal adenocarcinoma (PDAC) has remained largely unexplored. Herein, we report that ESE1 was found upregulated in primary PDAC compared to normal pancreatic tissue, but high expression of ESE1 correlated to better relapse‐free survival in patients with PDAC. Interestingly, ESE1 was found to exhibit dual roles in regulation of malignant properties of PDAC cells in that its overexpression promoted cell proliferation, whereas its downregulation enhanced epithelial‐mesenchymal transition (EMT) phenotype. In the context of TGF‐β‐induced EMT, ESE1 is markedly downregulated at post‐transcriptional level, and reconstituted ESE1 expression partially reversed TGF‐β‐induced EMT marker expression. Furthermore, we identify AGR2 as a novel transcriptional target of ESE1 that participates in TGF‐β‐induced EMT in PDAC. Collectively, our findings reveal an ESE1/AGR2 axis that interacts with TGF‐β signaling to modulate EMT phenotype in PDAC. [ABSTRACT FROM AUTHOR]

The TGF-β signaling pathway is involved in numerous cellular processes, and its deregulation may result in cancer development. One of the key processes in tumor progression and metastasis is epithelial to mesenchymal transition (EMT), in which TGF-β signaling plays important roles. Recently, AGR2 was identified as a crucial component of the cellular machinery responsible for maintaining the epithelial phenotype, thereby interfering with the induction of mesenchymal phenotype cells by TGF-β effects in cancer. Here, we performed transcriptomic profiling of A549 lung cancer cells with CRISPR-Cas9 mediated AGR2 knockout with and without TGF-β treatment. We identified significant changes in transcripts associated with focal adhesion and eicosanoid production, in particular arachidonic acid metabolism. Changes in transcripts associated with the focal adhesion pathway were validated by RT-qPCR of COL4A1, COL4A2, FLNA, VAV3, VEGFA, and VINC mRNAs. In addition, immunofluorescence showed the formation of stress fibers and vinculin foci in cells without AGR2 and in response to TGF-β treatment, with synergistic effects observed. These findings imply that both AGR2 downregulation and TGF-β have a role in focal adhesion formation and cancer cell migration and invasion. Transcripts associated with arachidonic acid metabolism were downregulated after both AGR2 knockout and TGF-β treatment and were validated by RT-qPCR of GPX2, PTGS2, and PLA2G4A. Since PGE2 is a product of arachidonic acid metabolism, its lowered concentration in media from AGR2-knockout cells was confirmed by ELISA. Together, our results demonstrate that AGR2 downregulation and TGF-β have an essential role in focal adhesion formation; moreover, we have identified AGR2 as an important component of the arachidonic acid metabolic pathway. [ABSTRACT FROM AUTHOR]

Acute pancreatitis (AP) is an inflammatory gastrointestinal disorder affecting the pancreas. Previous study reported that tetraspanin 1 (TSPAN1) expression was significantly upregulated in the pancreas of AP patients. However, the underlying molecular mechanism of TSPAN1 in the pathogenesis of AP remains unclear. Thus, the aim of the present study was to investigate the potential role of TSPAN1 in development of AP. RT‐qPCR was carried out to quantify the relative mRNA levels of TSPAN1 and anterior gradient‐2 (AGR2). The CCK‐8 assay was used to detect the cell viability. The TUNEL assay was performed to visualize the apoptotic cells. Western blot was performed to determine the expressions of proteins related to endoplasmic reticulum (ER) stress and apoptosis. ELISA kits were adopted to detect the concentration of inflammatory cytokines including TNF‐α and IL‐6. Finally, immunoprecipitation (IP) was used to verify the interaction between TSPAN1 and AGR2. TSPAN1 was upregulated in serum of AP patients and AP cell models. TSPAN1 silencing promoted the cell proliferation and inhibited inflammatory response in cerulein‐induced AR42J cells. Moreover, TSPAN1 induced endoplasmic reticulum stress by binding AGR2. Interestingly, the overexpression of AGR2 abolished the effects of TSPAN1 silencing on cell proliferation and inflammatory response in cerulein‐induced AR42J cells. In summary, TSPAN1 silencing protects against cerulein‐induced pancreatic acinar cell injury through inhibiting ER stress‐mediated by AGR2. Hence, TSPAN1 may serve as a promising therapeutic target for AP treatment. [ABSTRACT FROM AUTHOR]

125I seeds can effectively inhibit the growth of a variety of cancer cells. It has been used in the treatment of a variety of cancers, and has achieved certain curative effect. However, to the best of our knowledge, no report has described the effects of 125I seeds on the biological functions of cholangiocarcinoma (CCA) and the mechanisms underlying the effects of the seeds on this cancer. In this study, we demonstrated that 125I seeds could inhibit the proliferation, migration and invasion of CCA cells, as well as promoting apoptosis and blocking the cell cycle in these cells. Moreover, 125I seeds inhibited the growth of CCA xenografts and promoted the apoptosis of CCA cells in vivo. Furthermore, transcriptome sequencing showed that 125I seeds could inhibit the growth of CCA by inhibiting the expression of AGR2 and regulating p38 MAPK pathway. Finally, this finding indicated that 125I seeds can inhibit proliferation and promote apoptosis in CCA cells by inhibiting the expression of AGR2 and DUSP1 and increasing the expression of p-p38 MAPK and p-p53. This study provides a new research direction for studies investigating the mechanisms underlying the effects of 125I seeds on CCA. [ABSTRACT FROM AUTHOR]

The upregulation of anterior gradient 2 (AGR2) has been observed in cholangiocarcinoma (CCA) cells, nras-mutant zebrafish, and specimens derived from CCA patients. Our previous study reported AGR2 splicing into AGR2vH to facilitate CCA cell aggressiveness, while this work aims to investigate the molecular mechanisms underlying AGR2vH. First, AGR2vH upregulation was demonstrated in CCA tissues derived from patients. For in vitro studies, established AGR2vH-overexpressing KKU-213A cells were found to exhibit increased proliferation and clonogenicity. In vivo tumorigenicity assessed in a mouse model represented higher tumorigenic potential in AGR2vH-overexpressing cell xenograft mice. Next, LC-MS/MS was analyzed, indicating that AGR2vH may be associated with CCA cell proliferation via Wnt/ß-catenin signaling pathway activation, which was verified by ß-catenin expression and nuclear translocation. The current results provide evidence that AGR2vH upregulation promotes tumorigenicity in CCA cells linked with an alteration of CCA cell proteome. Upregulation of AGR2vH in CCA represented higher cell growth and tumorigenic potential through ß-catenin activation which was verified from an alteration in CCA cell proteome. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Epithelial ovarian cancer (EOC) is the most common gynecologic disorder. Even with the recent progresses made towards the use of new therapeutics, it still represents the most lethal gynecologic malignancy in women from developed countries. The discovery of the anterior gradient proteins AGR2 and AGR3, which are highly related members belonging to the protein disulfide isomerase (PDI) family, attracted researchers' attention due to their putative involvement in adenocarcinoma development. This review compiles the current knowledge on the role of the AGR family and the expression of its members in EOC and discusses the potential clinical relevance of AGR2 and AGR3 for EOC diagnosis, prognosis, and therapeutics. A better understanding of the role of the AGR family may thus provide new handling avenues for EOC patients. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

BACKGROUND: AGR2 expression is associated with luminal breast cancer. Overexpression of AGR2 is a predictor of poor prognosis. Several studies have found correlations between AGR2 in disseminated tumor cells (DTCs) in breast cancer patients. OBJECTIVE: This study aims to determine the correlation between anterior Gradient2 (AGR2) expression with the incidence of distant metastases in luminal breast cancer. METHODS: This study was an observational study using a cross-sectional method and was conducted at Wahidin Sudirohusodo Hospital and the network. ELISA methods examine AGR2 expression from blood serum of breast cancer patients. To compare the AGR2 expression in metastatic patients and the non-metastatic patient was tested with Mann Whitney test. The correlation of AGR2 expression and metastasis was tested with the Rank Spearman test. RESULTS: The mean value of AGR2 antibody expression on ELISA in this study was 2.90 ± 1.82 ng/dl, and its cut-off point was 2.1 ng/dl. Based on this cut-off point value, 14 subjects (66.7%) had overexpression of AGR2 serum ELISA, and 7 subjects (33.3%) had not. The mean value AGR2 was significantly higher in metastatic than not metastatic, 3.77 versus 1.76 (p < 0.01). The Spearman rank test obtained a p-value for the 2 tail test of 0.003 (p < 0.05), which showed a significant correlation of both, while the correlation coefficient of 0.612 showed a strong positive correlation of AGR2 overexpression and metastasis. CONCLUSIONS: AGR2 expression is correlated with metastasis in Luminal breast cancer. [ABSTRACT FROM AUTHOR]

Objective: To investigate the anterior gradient 2 (AGR2) m RNA expression, which performs various cellular functions such as cell migration, differentiation, and proliferation in tissue specimens from pituitary adenomas. Material and Methods: A total of 44 pituitary adenoma specimens (20 female/24 male) from patients, and ten normal brain tissues (5 female/5 male) operated for epilepsy surgery (control group) were included in the study. Specimens were stored at -80 °C throughout the study. Molecular assessment of pituitary adenomas and control brain tissues was performed to quantify m RNA expression of AGR2 using real-time PCR. Distribution of AGR2 mRNA expression levels was evaluated according to pituitary adenoma subtypes, tumor aggressiveness, or invasiveness. Results: Expression levels of AGR2 mRNA in corticotroph (n=5) and somatotroph adenomas (n=14) were higher compared to control brain tissues (p= 0.045 and p= 0.005, respec¬tively); however, expression levels of AGR2 mRNA in lactotroph (n=3), gonadotroph (n=14), and non-secretory adenomas (n=7) were similar to the control brain tissues. The thyrotroph adenoma (n=1) was not included in the analysis. Expression levels of AGR2 mRNA were similar in female and male patients. The expression levels of the AGR2 mRNA were higher in non-invasive tumors (n=20) than invasive tumors (n=24) (p=0.001), and in the non-aggressive tumors (n=27) than aggressive tumors (n=17) (p=0.018). A negative correlation between expression levels of AGR2 mRNA and Ki-67 labeling index (r=-0.328; p=0,029) was obtained. However, no correlation was found between the expression levels of AGR2 mRNA and age or maximum tumor diameter. Conclusion: AGR2 expression is inversely correlated to invasive-ness and aggressiveness, independently from age and sex in pituitary adenomas. [ABSTRACT FROM AUTHOR]

Background: Forkhead box protein A1 (FOXA1), acting as a transcriptional activator for liver-specific transcripts, plays a vital part in proliferation, apoptosis and cell cycle. Methods: The mRNA expression of FOXA1 in 90 HCC tissues and matched adjacent non-tumor tissues was determined by qRT-PCR. The downstream and upstream regulators of FOXA1 were identified by bioinformatics analysis and experimental confirmation. Results: We found out that the expression of FOXA1 was obviously higher in hepatocellular carcinoma (HCC) tissues than that in matched non-tumor tissues. Similarly, FOXA1 is also highly expressed in HCC cell lines as compared with normal human hepatic cell line L02. Clinical association analysis indicated that high expression of FOXA1 was prominently correlated with high HBV level, large tumor size, high venous infiltration, high Edmondson–Steiner grading, and advanced tumor-node-metastasis tumor stage. Furthermore, the in vitro tests showed that ectopic expression of FOXA1 promoted HepG2 cell proliferation and suppressed apoptosis. In contrast, the downregulation of FOXA1 inhibited cell proliferation, and induced apoptosis in Hep3B cells. To investigate the functional mechanism of FOXA1, anterior gradient 2 (AGR2), an executor in proliferation and apoptosis, was identified as the direct target gene of FOXA1. Meanwhile, we also found the expression of FOXA1 could be inhibited by miR-212-3p, which working as a tumor suppressor downregulated in HCC. Conclusion: We revealed that FOXA1 exerted its biological function by regulating AGR2 expression, and its ectopic expression may be blamed for low expression of miR-212-3p. [ABSTRACT FROM AUTHOR]

Background: Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death worldwide. LINC00460, a novel long non-coding RNA (lncRNA), was recently confirmed as an oncogene in various cancers. However, the biological function and underlying mechanism of LINC00460 in HCC is largely obscure. Methods: Fifty pairs of tumor tissue and adjacent normal tissues from HCC patients, as well as six HCC cell lines and a normal human hepatic epithelial cell line were subjected to qRT-PCR assay to evaluate the expression levels of LINC00460. CCK-8 assays were used to detect the proliferation of HCC cells. Transwell assay was used to measure the migration and invasion abilities of HCC cells. RNA pull-down and luciferase assays were performed to verify the direct interaction between LINC00460 and miR-342-3p. A xenograft model of HCC was established to validate the in vivo function of LINC00460 in HCC progression. Results: We firstly detected LINC00460 expression was significantly upregulated in both HCC tumor tissues and cell lines. The upregulation of LINC00460 was positively associated with HCC progression. Functionally, LINC00460 facilitated HCC cell proliferation, migration, and invasion capacities, which due to that LINC00460 could physically bind to and repress miR-342-3p to elevate the expression of AGR2. Conclusion: Our data firstly reveal the clinical relevance, biological function, and regulatory mechanism of LINC00460 in HCC development. LINC00460 promotes HCC progression by elevating AGR2 expression via sponging miR-342-3p, providing a promising therapeutic target for HCC treatment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Previous studies have shown that miRNAs involved in a number of biological processes, such as cell growth, development, differentiation, and apoptosis. The dysregulation of miRNA expression is associated with various diseases, including cervical cancer. However, the involvement of miR‐3647‐5p in the progression of tumors is unclear. In this study, we confirmed that miR‐3647‐5p was down‐regulated during cervical carcinogenesis and development, which was positively correlated with the prognosis of patients with cervical cancer. In addition, our study showed that miR‐3647‐5p can inhibit the proliferation of cervical cancer cells and promote apoptosis, suggesting that miR‐3647‐5p is involved in the development of cervical cancer as a tumor suppressor gene. Furthermore, we found that transcription factor TP53 could promote the expression of miR‐3647‐5p, suggesting that the dysfunction of miR‐3647‐5p in cervical cancer may be related to TP53. In addition, we also found that miR‐3647‐5p can inhibit the proliferation of cervical cancer cells and promote apoptosis by targeting AGR2. In summary, our research reveals that transcription factor TP53 promotes the expression of miR‐3647‐5p, while up‐regulated miR‐3647‐5p targets AGR2, inhibiting cervical cancer cell proliferation and promoting apoptosis. Our study reveals the mechanism of TP53/miR‐3647‐5p/AGR2 axis in cervical cancer, which may be useful for targeted therapy of cervical cancer. [ABSTRACT FROM AUTHOR]

Colorectal cancer is one of the leading causes of cancer-related deaths. Due to relapse after current therapy regimens, cancer stem cells (CSCs) are being studied to target this small tumor-initiating population. Anterior gradient 2 (AGR2), a disulfide isomerase protein, is a well-known pro-oncogenic/metastatic oncogene overexpressed in various tumor tissues, including colon cancer. We found that AGR2 was a novel stem cell marker that was regulated by the canonical Wnt/β-catenin pathway in colon CSCs. AGR2 was highly co-expressed with surface stem cell markers in spheroidal culture. Silencing of AGR2 resulted in decreased sphere-forming ability and down-regulated expression of stem cell markers, whereas the opposite effects were seen with AGR2 overexpression. Moreover, patients with high β-catenin and AGR2 expression showed lower overall survival than those with low expression. In conclusion, our study describes a novel role for AGR2 as a stem cell marker that is highly regulated by canonical Wnt/β-catenin signaling in colorectal cancer. • AGR2 is a novel stem cell marker regulated by canonical Wnt signaling pathway in colon CSCs. • AGR2 is highly co-expressed with surface CSC markers. • Only AGR2 can modulate/manipulate stemness function of CRC. [ABSTRACT FROM AUTHOR]

In recent years, the discovery of 'tumour niche', a microenvironment that favours tumour development has changed our perspective of cancer. This microenvironment generated by the tumour cells itself and surrounding cells is capable of providing essential elements for its growth. Consequently, the homoeostasis of the secretory pathway (SP) has become an essential player in cancer development. The SP not only promotes cellular adaptation to protein misfolding due to oncogenic transformation or challenging tumour niche but also allows tumour cells to produce specific secretomes. This impacts tumour cells in cis‐ or trans‐ as well as stromal cells in the tumour niche. In this context, the Anterior GRadient 2 (AGR2) protein has been identified as a key player. AGR2 is a protein disulphide isomerase that resides in the endoplasmic reticulum (ER) and mediates the formation of disulphide bonds, catalyses the cysteine‐based redox reactions and assists the quality control of proteins. AGR2 not only plays an essential role in the homoeostasis of the SP but also exerts pro‐oncogenic gain‐of‐function due to its reported mislocalisation in the tumour niche microenvironment. In this review, we summarise the dual role of AGR2, inside and outside the ER, on the tumour niche and its microenvironment. Review: Anterior Gradient 2 (AGR2), an ER‐resident protein (iAGR2), is also a secreted molecule (eAGR2) that plays a pivotal role in tumor niche establishment and, as a consequence, participates in inflammation, immunogenicity, Extracellular matrix (ECM) remodeling, Epithelial‐Mesenchymal transition (EMT) and angiogenesis. Here, we provide an in‐depth description of e/iAGR2 in the context of the tumor niche and how e/iAGR2, through the Tumor Niche Secretome (TNS), might play a role in these functions. [ABSTRACT FROM AUTHOR]

Abstract: The Agr (anterior gradient) group proteins belong to the family of proteins with a noncanonical thioredoxin motif and are involved in the regulation of various processes: embryonic development, regeneration, and oncogenesis. Normally, the human Agr2 gene is predominantly expressed in the secreting cells of mucin-producing organs. However, Agr2 is associated with active metastasis during the development of some types of malignant tumors. The molecular mechanism of its functioning is poorly understood. The model of Xenopus laevis embryos is one of the most convenient and available basic models for the proper study of various molecular mechanisms and signaling cascades of proteins. Previously, only the expression activity of the Agr genes was studied in this model; in particular, active expression of the Agr2 gene was demonstrated in the early stages of embryonic development and during tadpole regeneration of the tail and hindlimbs in Xenopus laevis. To begin the study on the molecular mechanism of the Agr2 protein functioning, it is necessary to obtain Agr2 specific antibodies and to test their effectiveness, which was the main goal of this work. The obtained purified antibodies were tested by the immunohistochemical method; as a result, the distribution pattern of the Agr2 protein during early development of the embryos and in regenerating tails of the tadpoles of Xenopus laevis, completely coinciding with the expression pattern of this gene, was first obtained. [ABSTRACT FROM AUTHOR]

Background Anterior Gradient (AGR) 2 concentration increases in the serum of tumor patients, and their diagnostic and prognostic significances were evaluated in some tumors. The previous works showed that AGR2 high express in nasopharyngeal carcinoma (NPC) biopsy tissues. However, whether AGR2 serves as a diagnostic and prognostic marker for NPC remains unclear. Methods 42 healthy volunteers, 34 breast cancer patients and 124 NPC patients were enrolled into this study, and the serum samples were collected from these healthy volunteers, breast cancer patients and NPC patients. Concomitantly, 79 frozen nasopharyngeal specimens consisted of 65 NPC tissues and 14 normal nasopharyngeal tissues were enrolled in the observation. The enzyme linked immunosorbent assay (ELISA) was used to estimate AGR2 concentration in the serum samples, and AGR2 mRNA expressions in the frozen tissue samples were detected by real time RT-PCR. Results The real time RT-PCR results showed that AGR2 mRNA level was increased in NPC tissues compared with the normal nasopharyngeal tissues ( p < 0.05). The ELISA data showed that AGR2 concentration in NPC serum was significantly higher in NPC patient serums than that in the health population ( p < 0.05). And, AGR2 expression showed a correlation with tumor node metastasis (TNM) grade ( p < 0.05) and Recurrence ( p < 0.05). Moreover, the cumulative survival rate of patients with high concentration of AGR2 was significantly lower than that of patients with low concentration of AGR2 ( p < 0.05), and the cumulative hazard rate of patients with high concentration of AGR2 was significantly higher than that with low concentration of AGR2 ( p < 0.05). Conclusion Serum AGR2 can be used as a serum marker for clinical prognosis of nasopharyngeal carcinoma. However, serum AGR2 levels could not provide advantages in clinical practice for the differential diagnosis of cancer. [ABSTRACT FROM AUTHOR]

Abstract: Anterior gradient 2 protein belongs to a family of chaperone‐like proteins, namely protein disulfide isomerase. Generally, AGR2 is highly expressed in mucus‐secreting cells and endocrine organs, and in this study, we aimed to evaluate AGR2 and cell cycle molecules in epithelial ovarian cancer and its implications on prognosis. One hundred seventy‐five patient's samples that were diagnosed with primary epithelial ovarian carcinoma were selected. All the patients were treated with platinum‐taxane standard chemotherapy after surgery and CA125 serum levels were routinely determined. Four‐micrometer‐thick sections were processed by immunohistochemistry using an automated immunostainer, Ventana BenchMark AutoStainer with AGR2, cyclin D1, p21WAF1, and p53. Forty‐nine of 167 cases (29.3%) showed strong to moderate cytoplasmic marking of AGR2, and 118 (70.7%) had weak to negative expression. The absence of the AGR2 protein was observed in high‐grade serous carcinoma (P < .001) and significantly associated with disease‐free survival (DFS; P = .034). The expression of G1‐S phase‐regulatory proteins showed loss of p21 in high‐grade serous carcinoma (P < .001) and was related with poor DFS (P = .003). Strong and diffuse immunoexpression of p53 plus complete absence of p53 staining was interpreted as likely indicating a TP53 gene mutation. This result showed worse DFS alone (P = .012) and combined with low levels of AGR2 (P = .005). The expression profile of AGR2 and cell cycle proteins here presented was showed as good prognosis marker in epithelial ovarian cancer. This finding suggests AGR2 and as putative biomarker of disease progression in chemotherapy‐treated high‐grade serous carcinoma patients. [ABSTRACT FROM AUTHOR]

Anterior gradient 2 (AGR2), an endoplasmic reticulum (ER)-resident protein-disulfide isomerase (PDI), is associated with cancer development and malignant progression. Here, we show that high level of AGR2 promotes the aggressive phenotype of prostate cancer (PCa) mouse models developed by either patient-derived xenografts or surgical intra-prostate implantation of PCa cells, associated with enrichment of the blood vessel network in tumor tissues. Angiogenesis markers VEGFR2 and CD34, accompanied with the invasive marker Vimentin, were predominantly stained in metastatic liver tissues. Secreted AGR2 was defined to enhance VEGFR2 activity as evidenced by physical interaction of purified recombinant human AGR2 (rhAGR2) with rhVEGFA through the formation of a disulfide bond. Mutant or deleted thioredoxin motif in rhAGR2 was also unable to bind to rhVEGFA that led to the significant abolishment in the vessel formation, but partially affecting the aggressive process, implicating alternative mechanisms are required for AGR2-conferring metastasis. Cytosolic AGR2 contributed to cell metastasis ascribed to its stabilizing effect on p65 protein, which subsequently activated the NF-κB and facilitated epithelial to mesenchymal transition (EMT). Importantly, GSH and cabozantinib, but not bevacizumab, effectively blocked the pro-angiogenic effect of rhAGR2 in vitro and in vivo , providing evidence that secreted AGR2 acts as a predictive biomarker for selection of angiogenesis-targeting therapeutic drugs based on its levels in the circular system. [ABSTRACT FROM AUTHOR]

AGR2 is a well-studied secreted protein that is involved in multiple biological processes including cell proliferation and migration. The mechanism by which AGR2 increases the growth and migration of non-small cell lung cancer cells (NSCLC) is still unknown. In this study, we report that AGR2 is directly targeted by miR-342-3p. Functional studies suggest that overexpression of miR-342-3p inhibits the proliferation and migration of non-small cell lung cancer cells. Overexpression of AGR2 counteracts the phenotypes induced by miR-342-3p. Moreover, AGR2 expression is up-regulated and negatively correlated with miR-342-3p levels in NSCLC cells and tissues. A meta-analysis of survival data indicates that NSCLC patients with high levels of AGR2 in their tumors have a worse prognosis. Collectively, the identification of miR-342-3p and AGR2 might facilitate the development of biomarkers and therapeutic targets for this devastating disease. [ABSTRACT FROM AUTHOR]

Background: During cancer progression, epithelial cancer cells can be reprogrammed into mesenchymal-like cells with increased migratory potential through the process of epithelial-mesenchymal transition (EMT), representing an essential step of tumor progression towards metastatic state. AGR2 protein was shown to regulate several cancer-associated processes including cellular proliferation, survival and drug resistance.Methods: The expression of AGR2 was analyzed in cancer cell lines exposed to TGF-β alone or to combined treatment with TGF-β and the Erk1/2 inhibitor PD98059 or the TGF-β receptor specific inhibitor SB431542. The impact of AGR2 silencing by specific siRNAs or CRISPR/Cas9 technology on EMT was investigated by western blot analysis, quantitative PCR, immunofluorescence analysis, real-time invasion assay and adhesion assay.Results: Induction of EMT was associated with decreased AGR2 along with changes in cellular morphology, actin reorganization, inhibition of E-cadherin and induction of the mesenchymal markers vimentin and N-cadherin in various cancer cell lines. Conversely, induction of AGR2 caused reversion of the mesenchymal phenotype back to the epithelial phenotype and re-acquisition of epithelial markers. Activated Smad and Erk signaling cascades were identified as mutually complementary pathways responsible for TGF-β-mediated inhibition of AGR2.Conclusion: Taken together our results highlight a crucial role for AGR2 in maintaining the epithelial phenotype by preventing the activation of key factors involved in the process of EMT. [ABSTRACT FROM AUTHOR]

Background: Meningioma tumors arise in arachnoid membranes, and are the most reported central nervous system (CNS) tumors worldwide. Up to 20% of grade I meningioma tumors reoccur and currently predictive cancer stem cells (CSCs) markers for aggressive and drug resistant meningiomas are scarce. Methods: Meningioma tissues and primary cell lines were investigated using whole transcriptome microarray analysis, immunofluorescence staining of CSCs markers (including CD133, Sox2, Nestin, and Frizzled 9), and drug treatment with cisplatin or etoposide. Results: Unsupervised hierarchical clustering of six meningioma samples separated tissues into two groups. Analysis identified stem cells related pathways to be differential between the two groups and indicated the de-regulation of the stem cell associated genes Reelin (RELN), Calbindin 1 (CALB1) and Anterior Gradient 2 Homolog (AGR2). Immunofluorescence staining for four tissues confirmed stemness variation in situ. Biological characterization of fifteen meningioma primary cell lines concordantly separated cells into two functionally distinct sub-groups. Pleomorphic cell lines (NG type) grew significantly faster than monomorphic cell lines (G type), had a higher number of cells that express Ki67, and were able to migrate aggressively in vitro. In addition, NG type cell lines had a lower expression of nuclear Caspase-3, and had a significantly higher number of CSCs co-positive for CD133+ Sox2+ or AGR2+ BMI1+. Importantly, these cells were more tolerant to cisplatin and etoposide treatment, showed a lower level of nuclear Caspase-3 in treated cells and harbored drug resistant CSCs. Conclusion: Collectively, analyses of tissues and primary cell lines revealed stem cell associated genes as potential targets for aggressive and drug resistant meningiomas. [ABSTRACT FROM AUTHOR]

Tamoxifen treatment in breast cancer patients is associated with increased risk of endometrial malignancies. Significantly, higher AGR2 expression was found in endometrial cancers that developed in women previously treated with tamoxifen compared to those who had not been exposed to tamoxifen. An association of elevated AGR2 level with myometrial invasion occurrence and invasion depth was also found. In vitro analyses identified a stimulatory effect of AGR2 on cellular proliferation. Although adverse tamoxifen effects on endometrial cells remain elusive, our work identifies elevated AGR2 as a candidate tamoxifen-dependent mechanism of action responsible for increased incidence of endometrial cancer. [ABSTRACT FROM AUTHOR]

Background: Anterior gradient 2 (AGR2) is a protein disulfide isomerase-like protein widely expressed in many normal tissues as well as cancers. In our study, non-neoplastic bronchial epithelial cells as well as non-small cell lung cancer (NSCLC) cells express AGR2 protein.Methods: AGR2 expression was analyzed on lung tissue microarrays. Tumor staining was correlated with clinical outcomes.Results: On a lung cancer tissue microarray using immunohistochemistry, expression levels in cancer showed generally decreasing intensities in order from adenocarcinomas with mucinous components, other adenocarcinomas, squamous carcinomas, to large cell carcinomas. The study cohort was comprised of 400 cases. As a group, there was a slight trend of lower expression with increasing tumor grade. AGR2 expression level was a significant predictor of overall survival in younger patients only. Patients under 65 with lower levels showed a significantly better survival for both men and women. Patients over 65, in contrast, showed no such trend.Conclusions: Nearly all NSCLC tumors show AGR2 expression. Lung cancer expression of AGR2 has prognostic value for younger patients. [ABSTRACT FROM AUTHOR]

Proteins targeted to secretory pathway enter the endoplasmic reticulum where they undergo post-translational modification and subsequent quality control executed by exquisite catalysts of protein folding, protein disulphide isomerases (PDIs). These enzymes can often provide strict conformational protein folding solutions to highly cysteine-rich cargo as they facilitate disulphide rearrangement in the endoplasmic reticulum. Under conditions when PDI substrates are not isomerised properly, secreted proteins can accumulate in the endoplasmic reticulum leading to endoplasmic reticulum stress initiation with implications for human disease development. Anterior Gradient-2 (AGR2) is an endoplasmic reticulum-resident PDI superfamily member that has emerged as a dominant effector of basic biological properties in vertebrates including blastoderm formation and limb regeneration. AGR2 perturbation in mammals influences disease processes including cancer progression and drug resistance, asthma, and inflammatory bowel disease. This review will focus on the molecular characteristics, function, and regulation of AGR2, views on its emerging biological functions and misappropriation in disease, and prospects for therapeutic intervention into endoplasmic reticulum-resident protein folding pathways for improving the treatment of human disease. [ABSTRACT FROM AUTHOR]

A simple and stable method for the detection of cancer biomarker anterior gradient homolog 2 (AGR2) using UV–vis spectrometry is described. The sensing system is constructed easily with magnetic beads, aptamer, its complementary probe, and regular-shaped gold nanoparticles. The designed aptasensor exhibits excellent efficiency, selectivity and sensitivity toward AGR2 protein detection, and shows a picomolar range of detection limit. This extraordinary performance can be attributed to the effective separation of magnetic beads, the highly selective Gquadruplex formation of AGR2 proteins recognized by aptamers, the unique optical properties of gold nanoparticles and the special sandwich structure of the aptasensor. [ABSTRACT FROM AUTHOR]

In the past decades, highly related members of the protein disulphide isomerase family, anterior gradient protein AGR2 and AGR3, attracted researchers’ attention due to their putative involvement in developmental processes and carcinogenesis. While AGR2 has been widely demonstrated as a metastasis-related protein whose elevated expression predicts worse patient outcome, little is known about AGR3's role in tumour biology. Thus, we aim to confront the issue of AGR3 function in physiology and pathology in the following review by comparing this protein with the better-described homologue AGR2. Relying on available data and in silico analyses, we show that AGR proteins are co-expressed or uncoupled in context-dependent manners in diverse carcinomas and healthy tissues. Further, we discuss plausible roles of both proteins in tumour-associated processes such as differentiation, proliferation, migration, invasion and metastasis. This work brings new hints and stimulates further thoughts on hitherto unresolved conundrum of anterior gradient protein function. [ABSTRACT FROM AUTHOR]

Background: Anterior gradient 2 (AGR2) has been implicated in tumor-associated phenotypes such as cell viability, invasion and metastasis in various human cancers. However, the tumor promoting activity of AGR2 has not yet been determined in biliary tract cancers. Thus, we examined the expression of AGR2 and its tumor-promoting activity in biliary tract cancer cells in this study. Methods: Expression of AGR2 mRNA and protein was analyzed by real time RT-PCR and western blotting, respectively. MTT assay was employed to measure cell viability and pulsed BrdU incorporation by proliferating cells was monitored by flow cytometry. Soft agar colony formation assay and transwell invasion assay were employed to determine anchorage-independent growth and in vitro invasion of the tumor cells, respectively. In vivo tumor formation was examined by injection of tumor cells into immunocompromised mice subcutaneously. Statistical analysis was performed with 2-tailed unpaired Student's t-test for continuous data and with one-way ANOVA for multiple group comparisons. Bonferroni tests were used for post hoc 2-sample comparisons. Results: AGR2 mRNA was detected in SNU-245, SNU-478, and SNU-1196 cell lines, and its protein expression was confirmed in SNU-478 and SNU-245 cell lines by western blot analysis. Knockdown of AGR2 expression with an AGR2-specific short hairpin RNA (shRNA) in SNU-478, an ampulla of Vater cancer cell line resulted in decreased cell viability and in decreased anchorage-independent growth by 98%. The AGR2 knockdown also increased the sensitivity of the cells to chemotherapeutic drugs, including gemcitabine, 5-fluorouracil and cisplatin. In addition, SNU-478 cells expressing AGR2-shRNA failed to form detectable tumor xenografts in nude mice, whereas control cells formed tumors with an average size of 179 ± 84 mm³ in 3 weeks. Overexpression of AGR2 in SNU-869 cells significantly increased cell viability through enhanced cell proliferation and the number of Matrigel™-invading cells compared with AGR2-negative SNU-869 cells. Conclusions: Our findings implicate that AGR2 expression augments tumor-associated phenotypes by increasing proliferative and invasive capacities of the ampulla of Vater cancer cells. [ABSTRACT FROM AUTHOR]

Background Through a transcriptome microarray analysis, we have isolated Anterior gradient protein 2 (AGR2) as a gene up-regulated in papillary thyroid carcinoma (PTC). AGR2 is a disulfide isomerase over-expressed in several human carcinomas and recently linked to endoplasmic reticulum (ER) stress. Here, we analyzed the expression of AGR2 in PTC and its functional role. Methods Expression of AGR2 was studied by immunohistochemistry and real time PCR in normal thyroids and in PTC samples. The function of AGR2 was studied by knockdown in PTC cells and by ectopic expression in non-transformed thyroid cells. The role of AGR2 in the ER stress was analyzed upon treatment of cells, expressing or not AGR2, with Bortezomib and analyzing by Western blot the expression levels of GADD153. Results PTC over-expressed AGR2 at mRNA and protein levels. Knockdown of AGR2 in PTC cells induced apoptosis and decreased migration and invasion. Ectopic expression of AGR2 in non-transformed human thyroid cells increased migration and invasion and protected cells from ER stress induced by Bortezomib. Conclusions AGR2 is a novel marker of PTC and plays a role in thyroid cancer cell survival, migration, invasion and protection from ER stress. [ABSTRACT FROM AUTHOR]

Abstract: Aims: The human Anterior Gradient-2 (AGR2) protein is strongly expressed in various human cancers, and it has been described to promote aggressive tumour features in some entities. So far, a comprehensive analysis of AGR2 expression in colorectal carcinomas has not been described. Methods: Normal intestinal cells and colorectal carcinoma cell lines were analysed for AGR2 expression. AGR2 protein expression was immunohistochemically analysed in 28 normal tissue samples and 1068 tissue samples of clinically well characterised colorectal carcinomas. For statistical analysis, chi square test, spearman rank correlations, Kaplan–Meier estimates (Log rank test) and Cox regression were applied to test for diagnostic or prognostic associations. Results: In the normal intestinal cell line and in normal colon mucosa AGR2 was found in all cases (n =28). In contrast, loss of AGR2 was found in all six analysed colorectal cancer cell lines and in 833/1068 (78%) of the colorectal carcinoma tissue samples analysed, and it was significantly associated with a higher tumour grade and tumour localisation in the left-sided colon. In addition to the conventional prognostic tumour parameters pT category, nodal status, metastasis and histological tumour grade the loss of AGR2 expression was significantly associated with reduced overall survival times in univariate and multivariate analyses, thus suggesting AGR2 as an independent prognostic factor in primary colorectal carcinoma. Conclusions: AGR2 is frequently lost in colorectal carcinomas and might be a novel independent prognostic factor for overall patient survival. [Copyright &y& Elsevier]

Anterior gradient protein 2 homolog (AGR2), an endoplasmic reticulum protein, is secreted in the tumor microenvironment. AGR2 is a member of the disulfide isomerase family, is highly expressed in multiple cancers, and promotes cancer metastasis. In this study, we found that etravirine, which is a non-nucleoside reverse transcriptase inhibitor, could induce AGR2 degradation via autophagy. Moreover, etravirine diminished proliferation, migration, and invasion in vitro. Moreover, in an orthotopic xenograft mouse model, the combination of etravirine and paclitaxel significantly suppressed cancer progression and metastasis. This drug may be a promising therapeutic agent for the treatment of ovarian cancer. [ABSTRACT FROM AUTHOR]

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. 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. [ABSTRACT FROM AUTHOR]

Abstract: The pro-metastatic protein anterior gradient-2 (AGR2) was previously demonstrated as a predictive factor of poor response to tamoxifen treatment. In this study we aimed to delineate the key signalling pathway that may contribute to regulation of AGR2 protein induction in order to identify novel targets to overcome tamoxifen resistance in tumour cells. Together, our data identify PDPK1-AKT as a pro-oncogenic signalling pathway that triggers AGR2 protein induction in response to tamoxifen and suggest that AKT inhibitors could be used as part of a therapeutic strategy to treat tamoxifen resistant, AGR2 over-expressing cancers. [Copyright &y& Elsevier]

Abstract: Anterior gradient 2 (AGR2) is a normal endoplasmic reticulum protein that has two important abnormal functions, amphibian limb regeneration and human cancer metastasis promotion. These normal intracellular and abnormal extracellular roles can be attributed to the multidomain structure of AGR2. The NMR structure shows that AGR2 consists of an unstructured N-terminal region followed by a thioredoxin fold. The protein exists in monomer–dimer equilibrium with a K d of 8.83μM, and intermolecular salt bridges involving E60 and K64 within the folded domain serve to stabilize the dimer. The unstructured region is primarily responsible for the ability of AGR2 to promote cell adhesion, while dimerization is less important for this activity. The structural data of AGR2 show a separation between potential catalytic redox activity and adhesion function within the context of metastasis and development. [Copyright &y& Elsevier]

Abstract: Anterior Gradient 2 (AGR2), an ER stress-inducible protein, has been reported to be localized in endoplasmic reticulum (ER) and its level is elevated in numerous metastatic cancers. Recently, it has been demonstrated that AGR2 is involved in the control of ER homeostasis. However, the molecular mechanism how AGR2 regulates ER stress response remains unclear. Herein we show that AGR2 homo-dimerizes through an intermolecular disulfide bond. Moreover, dimerization of AGR2 attenuates ER stress-induced cell death through the association with BiP/GRP78. Thus, these results suggest that dimerization of AGR2 is crucial in mediating the ER stress signaling pathway. [Copyright &y& Elsevier]

Abstract: Agr2 is a putative protein disulfide isomerase (PDI) initially identified as an estrogen-responsive gene in breast cancer cell lines. While Agr2 expression in breast cancer is positively correlated with estrogen receptor (ER) expression, it is upregulated in both hormone dependent and independent carcinomas. Several in vitro and xenograft studies have implicated Agr2 in different oncogenic features of breast cancer; however, the physiological role of Agr2 in normal mammary gland development remains to be defined. Agr2 expression is developmentally regulated in the mammary gland, with maximum expression during late pregnancy and lactation. Using a mammary gland specific knockout mouse model, we show that Agr2 facilitates normal lobuloalveolar development by regulating mammary epithelial cell proliferation; we found no effects on apoptosis in Agr2 -/- mammary epithelial cells. Consequently, mammary glands of Agr2 -/- females exhibit reduced expression of milk proteins, and by two weeks post-partum their pups are smaller in size. Utilizing a conditional mouse model, we show that Agr2 constitutive expression drives precocious lobuloalveolar development and increased milk protein expression in the virgin mammary gland. In vitro studies using knock down and overexpression strategies in estrogen receptor positive and negative mammary epithelial cell lines demonstrate a role for Agr2 in estradiol-induced cell proliferation. In conclusion, the estrogen-responsive Agr2, a candidate breast cancer oncogene, regulates epithelial cell proliferation and lobuloalveolar development in the mammary gland. The pro-proliferative effects of Agr2 may explain its actions in early tumorigenesis. [Copyright &y& Elsevier]

Abstract: The Anterior Gradient (AGR) genes AGR2 and AGR3 are part of the Protein Disulfide Isomerase (PDI) family and harbour core thioredoxin folds (CxxS motifs) that have the potential to regulate protein folding and maturation. A number of proteomics and transcriptomics screens in the fields of limb regeneration, cancer cell metastasis, pro-oncogenic oestrogen-signalling, and p53 regulation have identified AGR2 as a novel component of these signalling pathways. Curiously, despite the fact that the AGR2 and AGR3 genes are contiguous on chromosome 7p21.1-3, the AGR3 protein has rarely been identified in such OMICs screens along with AGR2 protein. Therefore there is little information on how AGR3 protein is expressed in normal and diseased states. A panel of three monoclonal antibodies was generated towards AGR3 protein for identifying novel clinical models that can be used to define whether AGR3 protein could play a positive or negative role in human cancer development. One monoclonal antibody was AGR3-specific and bound a linear epitope that could be defined using both pep-scan and phage-peptide library screening. Using this monoclonal antibody, endogenous AGR3 protein expression was shown to be cytosolic in four human ovarian cancer subtypes; serous, endometrioid, clear cell, and mucinous. Mucinous ovarian cancers produced the highest number of AGR3 positive cells. AGR3 expression is coupled to AGR2 expression only in mucinous ovarian cancers, whereas AGR3 and AGR2 expressions are uncoupled in the other three types of ovarian cancer. AGR3 expression in ovarian cancer is independent of oestrogen-receptor expression, which is distinct from the oestrogen-receptor dependent expression of AGR3 in breast cancers. Isogenic cancer cell models were created that over-express AGR3 and these demonstrated that AGR3 mediates cisplatin-resistance in mouse xenografts. These data indicate that AGR3 is over-expressed by a hormone (oestrogen-receptor α)-independent mechanism and identify a novel protein-folding associated pathway that could mediate resistance to DNA-damaging agents in human cancers. [Copyright &y& Elsevier]

In the present study, the human orthologue of the secreted Xenopus laevis anterior gradient 2 (AGR2) protein was evaluated as a potential serum biomarker of lung adenocarcinoma. AGR2 protein levels were preoperatively measured in the serum of 111 primary lung adenocarcinoma patients and in 46 non-cancer controls with subsequent calculation of sensitivity and specificity in comparison with serum CEA levels. Correlations with clinicopathological variables were also assessed and survival analyses were performed according to the Kaplan-Meier method and differences determined with the log-rank test. The mean serum AGR2 level of lung adenocarcinoma patients in each stage, even Stage I, was significantly higher than in non-cancer controls (P < 0.001 for all stages, Mann-Whitney U test). The sensitivity was 65.8% (52.9% for stage IA), even higher than that of CEA, which was 45.0% (29.4% for stage IA), and the specificity was 87.0% according to the ROC curve (AUC=0.858). Positive serum AGR2 expression was significantly associated with the incidence of recurrence after surgery (P=0.025) and with a poor prognosis (P=0.037 for overall survival and P=0.004 for disease-free survival). Preoperative serum AGR2 might become a clinically useful biomarker for early detection, prediction of recurrence and prognosis with lung adenocarcinomas. [ABSTRACT FROM AUTHOR]

BACKGROUND Endometriosis is a metastatic disease without obvious tumorigenesis. Expression of S100P, S100A4, osteopontin (OPN) or anterior gradient homologue 2 (AGR2) proteins can induce metastasis but fail to induce tumorigenesis per se. We now explore whether this group of metastasis-inducing proteins (MIPs) are associated with the pathogenesis of endometriosis. METHODS Eutopic endometrial biopsies were taken from 73 women (35 fertile women without endometriosis and 38 women with surgically diagnosed endometriosis). Ectopic endometriotic lesions were collected from eight of the women with endometriosis. The expression of MIPs at the cellular level was evaluated by immunohistochemistry and the presence of these proteins in the endometrial tissues was verified by western blotting and their gene expression was confirmed by RT–PCR. RESULTS All four MIPs were immunolocated in the endometrium of control women and S100P, AGR2 and OPN showed a cyclical variation. Proliferative phase eutopic endometrium of both groups showed a similar staining pattern for all MIPs, whereas secretory phase endometrium showed a differential expression between controls and cases. The secretory phase endometrial immunostaining of controls showed weak stromal and perivascular AGR2, and decreased stromal and glandular S100P. In contrast, immunostaining for all MIPs was increased in the late secretory endometrial samples of women with endometriosis and intense immunostaining was seen for S100A4 in the stroma (P< 0.05) and for S100P (P< 0.001) and AGR2 (P< 0.0001) in both glands and stroma (P< 0.001). All active peritoneal endometriotic lesions showed strong immunostaining for each of the MIPs studied. CONCLUSIONS We propose that these MIPs enhance endometrial cell invasiveness and contribute to the establishment of ectopic endometriotic deposits after retrograde menstruation. [ABSTRACT FROM PUBLISHER]

In a search for proteins involved in cancer metastasis, we analyzed proteomes of the human gastric cancer cell OCUM-2M and its metastatic subline OCUM-2MLN. We observed that aspartate aminotransferase (AAT), D-site binding protein (DBP), and anterior gradient protein 2 (AGR2) are differentially expressed in metastatic OCUM-2MLN cells. Measurement of protein expression in clinical samples indicated that DBP and AAT are also down-regulated in metastatic adenocarcinoma. Additionally, urokinase-type tissue plasminogen activator is up-regulated in OCUM-2MLN cells and also in metastatic gastric cancer samples. Collectively, these results raise a possibility that AAT, DBP and AGR2 are functionally implicated in the invasiveness of gastric cancer cells. [ABSTRACT FROM AUTHOR]

Abstract: AGR2 has evolutionarily conserved roles in development and tissue regeneration and is linked with several human cancers. The exact functions and regulation of AGR2 are poorly understood, but current data identify AGR2 as a clinically relevant factor that modulates the behavior and response of hormone-dependent cancers (breast, prostate) and hormone-independent cancers (colorectal, pancreatic, esophageal and other common cancers). AGR2 protein expression induces metastasis, acts as a p53 tumor suppressor inhibitor and survival factor, participates directly in neoplastic transformation and is involved in drug resistance. Thus, AGR2 is an important tumor biomarker and negative prognostic factor potentially exploitable in clinical practice. [Copyright &y& Elsevier]

The anterior gradient protein-2 (AGR2) is overexpressed in numerous tumours such as breast, prostate or pancreas carcinomas and recently reported in fibrolamellar hepatocellular carcinoma (HCC). In the present study, we further describe AGR2 expression patterns all along the adult and fetal biliary tree and in cholangiocarcinomas. Immunohistochemistry using anti-AGR2 antibodies was performed in adult and fetal livers, gallbladders as well as cholangiocarcinomas and HCCs. In adult and fetal liver, the tall epithelial cells covering the large bile ducts as well as gallbladder epithelial cells showed strong AGR2 staining. Hilar and extrahepatic cholangiocarcinomas, and a subset of intrahepatic cholangiocarcinomas, which displayed a morphological mucus-excreting feature, also displayed AGR2 expression. In contrast, AGR2 expression was not detected in typical HCCs. Our study shows that the differential expression of AGR2 is a phenotypic feature of the cholangiocytes covering different segments of the biliary tree. This pattern of expression is conserved during fetal and adult life, as well as during biliary carcinogenesis. [ABSTRACT FROM AUTHOR]

Abstract: Anterior gradient-2 (AGR2) functions in a range of biological systems, including goblet cell formation, limb regeneration, inhibition of p53, and metastasis. There are no well-validated binding proteins for AGR2 protein despite the wealth of data implicating an important cellular function in vertebrates. The yeast two-hybrid system was used to isolate the ATP binding protein Reptin as an AGR2-interacting protein. AGR2 formed a stable complex in human cell lysates with Reptin, thus validating Reptin as an AGR2 binding protein in cells. Reptin was also shown to be overproduced in a panel of primary breast cancer biopsy specimens, relative to normal adjacent tissue from the same patient, suggesting a role in cancer growth in vivo. Mutations were made at the two ATP binding motifs in Reptin to evaluate the effects of ATP on Reptin–AGR2 complex stability. Loss-of-ATP binding mutations at the Walker A motif (K83A) or gain-of-ATP binding mutations at the Walker B motif (D299N) resulted in Reptin mutants with altered oligomerization, thermostability, and AGR2 binding properties. These data indicate that the two ATP binding motifs of Reptin play a role in regulating the stability of the AGR2–Reptin complex. The minimal region of AGR2 interacting with Reptin was localized using overlapping peptide libraries derived from the AGR2 protein sequence. The Reptin docking site was mapped to a divergent octapeptide loop in the AGR2 superfamily between amino acids 104 and 111. Mutations at codon Y104 or F111 in full-length AGR2 destabilized the binding of Reptin. These data highlight the existence of a protein docking motif on AGR2 and an ATP-regulated peptide-binding activity for Reptin. This knowledge has implications for isolating other AGR2-interacting proteins, for developing assays to isolate small molecules that target the Reptin ATP binding site, and for measuring the effects of the Reptin–AGR2 complex in cancer cell growth. [Copyright &y& Elsevier]