Anterior gradient 2 is induced in cutaneous wound and promotes wound healing through its adhesion domain

Loss of the ability to regenerate body appendages in vertebrates: from side effects of evolutionary innovations to gene loss

The ability to regenerate large body appendages is an ancestral trait of vertebrates, which varies across different animal groups. While anamniotes (fish and amphibians) commonly possess this ability, it is notably restricted in amniotes (reptiles, birds, and mammals). In this review, we explore the factors contributing to the loss of regenerative capabilities in amniotes. First, we analyse the potential negative impacts on appendage regeneration caused by four evolutionary innovations: advanced immunity, skin keratinization, whole-body endothermy, and increased body size. These innovations emerged as amniotes transitioned to terrestrial habitats and were correlated with a decline in regeneration capability. Second, we examine the role played by the loss of regeneration-related enhancers and genes initiated by these innovations in the fixation of an inability to regenerate body appendages at the genomic level. We propose that following the cessation of regenerative capacity, the loss of highly specific regeneration enhancers could represent an evolutionarily neutral event. Consequently, the loss of such enhancers might promptly follow the suppression of regeneration as a side effect of evolutionary innovations. By contrast, the loss of regeneration-related genes, due to their pleiotropic functions, would only take place if such loss was accompanied by additional evolutionary innovations that compensated for the loss of pleiotropic functions unrelated to regeneration, which would remain even after participation of these genes in regeneration was lost. Through a review of the literature, we provide evidence that, in many cases, the loss in amniotes of genes associated with body appendage regeneration in anamniotes was significantly delayed relative to the time when regenerative capability was lost. We hypothesise that this delay may be attributed to the necessity for evolutionary restructuring of developmental mechanisms to create conditions where the loss of these genes was a beneficial innovation for the organism. Experimental investigation of the downregulation of genes involved in the regeneration of body appendages in anamniotes but absent in amniotes offers a promising avenue to uncover evolutionary innovations that emerged from the loss of these genes. We propose that the vast majority of regeneration-related genes lost in amniotes (about 150 in humans) may be involved in regulating the early stages of limb and tail regeneration in anamniotes. Disruption of this stage, rather than the late stage, may not interfere with the mechanisms of limb and tail bud development during embryogenesis, as these mechanisms share similarities with those operating in the late stage of regeneration. Consequently, the most promising approach to restoring regeneration in humans may involve creating analogs of embryonic limb buds using stem cell-based tissue-engineering methods, followed by their transfer to the amputation stump. Due to the loss of many genes required specifically during the early stage of regeneration, this approach may be more effective than attempting to induce both early and late stages of regeneration directly in the stump itself.

Enhancing protein delivery for tissue regeneration: Development of AGR2-loaded hydrogels with controlled release properties

The growth factor Anterior Gradient 2 (AGR2) has been shown to have an effective role in tissue regeneration, but remained largely unexplored in localized tissue engineering applications. Alginate beads have been proven as safe carriers for protein encapsulation, but they suffer from fragility and uncontrolled protein release. For such alginate systems, little is known about how changes in concentrations and ion-crosslinking affect protein release and accumulation in 3-D matrices. To address these questions, an engineered interpenetrating polymer network (IPN) has been used to synthesize a novel hybrid system consisting of AGR2 loaded beads composed of calcium-crosslinked sodium alginate (SA) and carboxymethyl cellulose (CMC). These beads are embedded in films consisting of SA and polyvinyl alcohol (PVA), using a simple ion gelation technique. We assess protein release kinetics and accumulation within the hybrid system by varying polymer concentrations and cross-linking parameters. The IPN hybrid system maintains controlled release over two weeks, without an initial burst period. Through this approach efficicnt delivery of AGR2 is achieved which in turn effectively mediates cell migration and proliferation, resulting in excellent cell viability and complete wound closure. The described release system opens new perspectives in tissue engineering.

Comparison between Cultivated Oral Mucosa and Ocular Surface Epithelia for COMET Patients Follow-Up

Total bilateral Limbal Stem Cell Deficiency is a pathologic condition of the ocular surface due to the loss of corneal stem cells. Cultivated oral mucosa epithelial transplantation (COMET) is the only autologous successful treatment for this pathology in clinical application, although abnormal peripheric corneal vascularization often occurs. Properly characterizing the regenerated ocular surface is needed for a reliable follow-up. So far, the univocal identification of transplanted oral mucosa has been challenging. Previously proposed markers were shown to be co-expressed by different ocular surface epithelia in a homeostatic or perturbated environment. In this study, we compared the transcriptome profile of human oral mucosa, limbal and conjunctival cultured holoclones, identifying Paired Like Homeodomain 2 (PITX2) as a new marker that univocally distinguishes the transplanted oral tissue from the other epithelia. We validated PITX2 at RNA and protein levels to investigate 10-year follow-up corneal samples derived from a COMET-treated aniridic patient. Moreover, we found novel angiogenesis-related factors that were differentially expressed in the three epithelia and instrumental in explaining the neovascularization in COMET-treated patients. These results will support the follow-up analysis of patients transplanted with oral mucosa and provide new tools to understand the regeneration mechanism of transplanted corneas.

Potential Role of AGR2 for Mammalian Skin Wound Healing

The limited ability of mammals to regenerate has garnered significant attention, particularly in regard to skin wound healing (WH), which is a critical step for regeneration. In human adults, skin WH results in the formation of scars following injury or trauma, regardless of severity. This differs significantly from the scarless WH observed in the fetal skin of mammals or anamniotes. This review investigates the role of molecular players involved in scarless WH, which are lost or repressed in adult mammalian WH systems. Specifically, we analyze the physiological role of Anterior Gradient (AGR) family proteins at different stages of the WH regulatory network. AGR is activated in the regeneration of lower vertebrates at the stage of wound closure and, accordingly, is important for WH. Mammalian AGR2 is expressed during scarless WH in embryonic skin, while in adults, the activity of this gene is normally inhibited and is observed only in the mucous epithelium of the digestive tract, which is capable of full regeneration. The combination of AGR2 unique potencies in postnatal mammals makes it possible to consider it as a promising candidate for enhancing WH processes.

AGR2: a secreted protein worthy of attention in diagnosis and treatment of breast cancer

AGR2 is a secreted protein widely existing in breast. In precancerous lesions, primary tumors and metastatic tumors, the expression of AGR2 is increased, which has aroused our interest. This review introduces the gene and protein structure of AGR2. Its endoplasmic reticulum retention sequence, protein disulfide isomerase active site and multiple protein binding sequences endow AGR2 with diverse functions inside and outside breast cancer cells. This review also enumerates the role of AGR2 in the progress and prognosis of breast cancer, and emphasizes that AGR2 can be a promising biomarker and a target for immunotherapy of breast cancer, providing new ideas for early diagnosis and treatment of breast cancer.

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.

Autophagy and gastrointestinal cancers: the behind the scenes role of long non-coding RNAs in initiation, progression, and treatment resistance

Gastrointestinal (GI) cancers comprise a heterogeneous group of complex disorders that affect different organs, including esophagus, stomach, gallbladder, liver, biliary tract, pancreas, small intestine, colon, rectum, and anus. Recently, an explosion in nucleic acid-based technologies has led to the discovery of long non-coding RNAs (lncRNAs) that have been found to possess unique regulatory functions. This class of RNAs is >200 nucleotides in length, and is characterized by their lack of protein coding. LncRNAs exert regulatory effects in GI cancer development by affecting different functions such as the proliferation and metastasis of cancer cells, apoptosis, glycolysis and angiogenesis. Over the past few decades, considerable evidence has revealed the important role of autophagy in both GI cancer progression and suppression. In addition, recent studies have confirmed a significant correlation between lncRNAs and the regulation of autophagy. In this review, we summarize how lncRNAs play a behind the scenes role in the pathogenesis of GI cancers through regulation of autophagy.

Novel tissue-engineered skin equivalent from recombinant human collagen hydrogel and fibroblasts facilitated full-thickness skin defect repair in a mouse model

Tissue-engineered skin equivalent (TESE) is an optimized alternative for the treatment of skin defects. Designing and fabricating biomaterials with desired properties to load cells is critical for the approach. In this study, we aim to develop a novel TESE with recombinant human collagen (rHC) hydrogel and fibroblasts to improve full-thickness skin defect repair. First, the bioactive effect of rHC on fibroblast proliferation, migration and phenotype was assayed. The results showed that rHC had good biocompatibility and could stimulate fibroblasts migration and secrete various growth factors. Then, rHC was cross-linked with transglutaminase (TG) to prepare rHC hydrogel. Rheometer tests indicated that 10% rHC/TG hydrogel could reach a oscillate stress of 251 Pa and remained stable. Fibroblasts were seeded into rHC/TG hydrogel to prepare TESE. Confocal microscope and scanning electronic microscope observation showed that seeded fibroblasts survived well in the hydrogel. Finally, the therapeutic effect of the newly prepared TESE was tested in a mouse full-thickness skin defect model. The results demonstrated that TESE could significantly improve skin defect repair in vivo. Conclusively, TESE prepared from rHC and fibroblasts in this study exhibits great potential for clinical application in the future.

The Secreted Protein Disulfide Isomerase Ag1 Lost by Ancestors of Poorly Regenerating Vertebrates Is Required for Xenopus laevis Tail Regeneration

Warm-blooded vertebrates regenerate lost limbs and their parts in general much worse than fishes and amphibians. We previously hypothesized that this reduction in regenerative capability could be explained in part by the loss of some genes important for the regeneration in ancestors of warm-blooded vertebrates. One of such genes could be ag1, which encodes secreted protein disulfide isomerase of the Agr family. Ag1 is activated during limb and tail regeneration in the frog Xenopus laevis tadpoles and is absent in warm-blooded animals. The essential role of another agr family gene, agr2, in limb regeneration was demonstrated previously in newts. However, agr2, as well as the third member of agr family, agr3, are present in all vertebrates. Therefore, it is important to verify if the activity of ag1 lost by warm-blooded vertebrates is also essential for regeneration in amphibians, which could be a further argument in favor of our hypothesis. Here, we show that in the Xenopus laevis tadpoles in which the expression of ag1 or agr2 was artificially suppressed, regeneration of amputated tail tips was also significantly reduced. Importantly, overexpression of any of these agrs or treatment of tadpoles with any of their recombinant proteins resulted in the restoration of tail regeneration in the refractory period when these processes are severely inhibited in normal development. These findings demonstrate the critical roles of ag1 and agr2 in regeneration in frogs and present indirect evidence that the loss of ag1 in evolution could be one of the prerequisites for the reduction of regenerative ability in warm-blooded vertebrates.

Extracellular AGR2 activates neighboring fibroblasts through endocytosis and direct binding to β-catenin that requires AGR2 dimerization and adhesion domains

Anterior gradient 2 (AGR2) is often overexpressed in several types of cancer. AGR2 is cytoplasmic or secreted as an extracellular signal. Intracellular AGR2 properties and role in cancer have been well studied, but its extracellular function is largely unclear. It has been shown that extracellular AGR2 activates endothelial cells and fibroblasts in culture, but the mechanism of AGR2 signaling is not well elucidated. Here, we report that tumor secreted or externally added AGR2 translocates into cytoplasm by endocytosis, binds to β-catenin and further co-translocates to the nucleus in NIH3T3 fibroblasts. Externally added AGR2 also increased β-catenin expression, stability, and accumulation in the nucleus in both fibroblasts and cancer cells. External AGR2 rescued the expression of β-catenin, which was suppressed by EGFR inhibitor AG1478 indicating an alternative pathway to regulate β-catenin independent of EGFR signal. These effects were abolished when a monoclonal antibody against AGR2 was added to the experiments, confirming the effects are caused by AGR2 only. Putting together, our results show that extracellular AGR2 signaling pathway involves endocytosis mediated cellular translocation, direct binding and regulating β-catenin nuclear accumulation. It is also a target against tumor initiated AGR2 signaling to form and maintain tumor microenvironment.

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.

Potential Role of Epithelial Endoplasmic Reticulum Stress and Anterior Gradient Protein 2 Homologue in Crohn's Disease Fibrosis

BACKGROUND AND AIMS

Intestinal fibrosis is a common complication of Crohn's disease [CD]. It is characterised by an accumulation of fibroblasts differentiating into myofibroblasts secreting excessive extracellular matrix. The potential role of the intestinal epithelium in this fibrotic process remains poorly defined.

METHODS

We performed a pilot proteomic study comparing the proteome of surface epithelium, isolated by laser-capture microdissection, in normal and fibrotic zones of resected ileal CD strictures [13 zones collected in five patients]. Proteins of interests were validated by immunohistochemistry [IHC] in ileal and colonic samples of stricturing CD [n = 44], pure inflammatory CD [n = 29], and control [n = 40] subjects. The pro-fibrotic role of one selected epithelial protein was investigated through in-vitro experiments using HT-29 epithelial cells and a CCD-18Co fibroblast to myofibroblast differentiation model.

RESULTS

Proteomic study revealed an endoplasmic reticulum [ER] stress proteins increase in the epithelium of CD ileal fibrotic strictures, including anterior gradient protein 2 homologue [AGR2] and binding-immunoglobulin protein [BiP]. This was confirmed by IHC. In HT-29 cells, tunicamycin-induced ER stress triggered AGR2 intracellular expression and its secretion. Supernatant of these HT-29 cells, pre-conditioned by tunicamycin, led to a myofibroblastic differentiation when applied on CCD-18Co fibroblasts. By using recombinant protein and blocking agent for AGR2, we demonstrated that the secretion of this protein by epithelial cells can play a role in the myofibroblastic differentiation.

CONCLUSIONS

The development of CD fibrotic strictures could involve epithelial ER stress and particularly the secretion of AGR2.

Anterior gradient 2 is involved in the post-transcriptional regulation of β-dystroglycan

Anterior gradient 2 (AGR2) is a protein disulfide isomerase over-expressed in numerous types of cancer. Although AGR2 plays a role in ER homeostasis, its function(s) in tumorigenesis is still elusive. Here we demonstrate that AGR2 is involved in the regulation of the β-subunit of dystroglycan (β-DG), a component of the multi-protein complex linking the extracellular matrix and cytoskeletal network. In breast cancer cells, AGR2 over-expression led to the up-regulation of β-DG but not that of α-DG, while the transcript levels of these subunits were unchanged. Conversely, the reduced expression of AGR2 caused the down-regulation of β-DG. Interestingly, induced expression of AGR2 increased the degree of co-localization of AGR2 and β-DG in the cytoplasm suggesting that AGR2 facilitates the trafficking of β-DG. In addition, AGR2 over-expression caused the re-arrangement of the actin cytoskeletal network. Presumably over-expressed AGR2 up-regulates β-DG post-transcriptionally and facilitates its trafficking, which then causes re-arrangement of the cytoskeletal network, which plays a role in the adhesion and invasion of cancer cells.

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.

Novel epoxy-tiglianes stimulate skin keratinocyte wound healing responses and re-epithelialization via protein kinase C activation

Epoxy-tiglianes are a novel class of diterpene esters. The prototype epoxy-tigliane, EBC-46 (tigilanol tiglate), possesses potent anti-cancer properties and is currently in clinical development as a local treatment for human and veterinary cutaneous tumors. EBC-46 rapidly destroys treated tumors and consistently promotes wound re-epithelialization at sites of tumor destruction. However, the mechanisms underlying these keratinocyte wound healing responses are not completely understood. Here, we investigated the effects of EBC-46 and an analogue (EBC-211) at 1.51 nM-151 µM concentrations, on wound healing responses in immortalized human skin keratinocytes (HaCaTs). Both EBC-46 and EBC-211 (1.51 nM-15.1 µM) accelerated G0/G1-S and S-G2/M cell cycle transitions and HaCaT proliferation. EBC-46 (1.51-151 nM) and EBC-211 (1.51 nM-15.1 µM) further induced significant HaCaT migration and scratch wound repopulation. Stimulated migration/wound repopulation responses were even induced by EBC-46 (1.51 nM) and EBC-211 (1.51-151 nM) with proliferation inhibitor, mitomycin C (1 μM), suggesting that epoxy-tiglianes can promote migration and wound repopulation independently of proliferation. Expression profiling analyses showed that epoxy-tiglianes modulated keratin, DNA synthesis/replication, cell cycle/proliferation, motility/migration, differentiation, matrix metalloproteinase (MMP) and cytokine/chemokine gene expression, to facilitate enhanced responses. Although epoxy-tiglianes down-regulated established cytokine and chemokine agonists of keratinocyte proliferation and migration, enhanced HaCaT responses were demonstrated to be mediated via protein kinase C (PKC) phosphorylation and significantly abrogated by pan-PKC inhibitor, bisindolylmaleimide-1 (BIM-1, 1 μM). By identifying how epoxy-tiglianes stimulate keratinocyte healing responses and re-epithelialization in treated skin, our findings support the further development of this class of small molecules as potential therapeutics for other clinical situations associated with impaired re-epithelialization, such as non-healing skin wounds.

Novel Biomedical Functions of Surfactin A from Bacillus subtilis in Wound Healing Promotion and Scar Inhibition

Surfactin produced by Bacillus subtilis is a powerful biosurfactant in food, cosmetics, and pesticide industries. However, its suitability in wound healing applications is uncertain. In this article, we determined the effects of surfactin A from B. subtilis on wound healing, angiogenesis, cell migration, inflammatory response, and scar formation. The results indicated that 80.65 ± 2.03% of surfactin A-treated wounds were closed, whereas 44.30 ± 4.26% of the vehicle-treated wound areas remained open on day 7 (P < 0.05). In mechanisms, it upregulated the expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF), accelerated keratinocyte migration through mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways, and regulated the secretion of proinflammatory cytokines and macrophage phenotypic switch. More attractive, surfactin A showed a seductive capability to inhibit scar tissue formation by affecting the expression of α-smooth muscle actin (α-SMA) and transforming growth factor (TGF-β). Overall, the study revealed a new function and potential of surfactin A as an affordable and efficient wound healing drug.

Paracrine signalling of AGR2 stimulates RhoA function in fibroblasts and modulates cell elongation and migration

The most prominent cancer-associated fibroblasts (CAFs) in tumor stroma is known to form a protective structure to support tumor growth. Anterior gradient-2 (AGR2), a tumor secretory protein is believed to play a pivotal role during tumor microenvironment (TME) development. Here, we report that extracellular AGR2 enhances fibroblasts elongation and migration significantly. The early stimulation of RhoA showed the association of AGR2 by upregulation of G1-S phase-regulatory protein cyclin D1 and FAK phosphorylation through fibroblasts growth factor receptor (FGFR) and vascular endothelial growth factor receptor (VEGFR). Our finding indicates that secretory AGR2 alters fibroblasts elongation, migration, and organization suggesting the secretory AGR2 as a potential molecular target that might be responsible to alter fibroblasts infiltration to support tumor growth.

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.

Leveraging the Role of the Metastatic Associated Protein Anterior Gradient Homologue 2 in Unfolded Protein Degradation: A Novel Therapeutic Biomarker for Cancer

Effective diagnostic, prognostic and therapeutic biomarkers can help in tracking disease progress, predict patients’ survival, and considerably affect the drive for successful clinical management. The present review aims to determine how the metastatic-linked protein anterior gradient homologue 2 (AGR2) operates to affect cancer progression, and to identify associated potential diagnostic, prognostic and therapeutic biomarkers, particularly in central nervous system (CNS) tumors. Studies that show a high expression level of AGR2, and associate the protein expression with the resilience to chemotherapeutic treatments or with poor cancer survival, are reported. The primary protein structures of the seven variants of AGR2, including their functional domains, are summarized. Based on experiments in various biological models, this review shows an orchestra of multiple molecules that regulate AGR2 expression, including a feedback loop with p53. The AGR2-associated molecular functions and pathways including genomic integrity, proliferation, apoptosis, angiogenesis, adhesion, migration, stemness, and inflammation, are detailed. In addition, the mechanisms that can enable the rampant oncogenic effects of AGR2 are clarified. The different strategies used to therapeutically target AGR2-positive cancer cells are evaluated in light of the current evidence. Moreover, novel associated pathways and clinically relevant deregulated genes in AGR2 high CNS tumors are identified using a meta-analysis approach.

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.

Finite cell lines of turkey sperm storage tubule cells: ultrastructure and protein analysis

Cell lines of turkey sperm storage tubule (SST) epithelial cells were established. Turkey SSTs were dissected from freshly obtained uterovaginal junction (UVJ) tissue and placed in explant culture on various substrates and media. Primary cultures of SST epithelium only survived and grew from SST explants that were cultured on inactivated Sandoz inbred strain, thioguanine- and ouabain-resistance (STO) mouse feeder-cell layers in 12% fetal bovine serum-supplemented Dulbecco's Modified Eagle Medium mixed 1:1 with F12 nutrient mixture. Three independent primary colonies gave rise to 3 finite cell lines, SST-1, -2, and -3, which were continuously cultured for 8 to 16 passages at 1:3 passage ratios over a period of 3 to 4 mo. The cells were passaged by pretreatment with Y27632 and dissociation with Accutase. The SST cells grew as tightly knit monolayers on top of the feeder cells at a slow rate (approximately 96 h doubling time) at a medium pH of approximately 6.9. Lipid vacuoles were visible by light microscopy in the cells particularly at the periphery of growth. Transmission electron microscopy revealed the cells to be a polarized epithelium with apical microvilli and to have lateral tight-junction-like unions and associated desmosomes. Numerous secretory vesicles filled the upper portion of the cells’ cytoplasm, and nuclei and other major organelles such as mitochondria, rough endoplasmic reticulum, and Golgi apparatus were distributed somewhat lower in the cytoplasm. The secretory vesicles resembled mucin secretory vesicles. Proteomic analysis by mass spectroscopy of the conditioned medium of the cells, and of the cells themselves, showed the cell lines did not secrete large amounts of any particular protein, and the analysis confirmed their epithelial character. In conclusion, the SST-derived cell lines resembled the mucus-secreting cells found in the epithelium lining the UVJ of the turkey's reproductive tract.

An aberrantly spliced isoform of anterior gradient-2, AGR2vH promotes migration and invasion of cholangiocarcinoma cell

Cholangiocarcinoma (CCA) is a cancer of bile duct, considered to be an incurable and lethal cancer. High mortality rate of CCA patients is underlined by cancer metastasis, an ability of the cancer cells that spread to secondary organs. Recently, we have identified Anterior Gradient-2 (AGR2), from a pair of non-metastatic/metastatic cell lines (KKU-213/KKU-213L5), as a gene that is highly and specifically upregulated in the metastatic cell line. AGR2 encodes for a disulfide isomerase enzyme, ubiquitously detected in mucus-secreting tissues. Overexpression of AGR2 has been reported in several types of human cancer. Role of the overexpressed AGR2 in cancer is still unclear. Here, we found that upregulation of AGR2 in metastatic CCA cells coincides with an aberrant splicing of AGR2 mRNA, and that isoforms of AGR2 RNA, such as AGR2vE, AGR2vF, and AGR2vH are specific to the metastatic cells. We demonstrated that the AGR2vH isoform enables metastatic-associated phenotypes in CCA cells. Depletion of AGR2vH by an isoform-specific interfering RNA in metastatic KKU-213L5 cell results in significant reduction of cancer cell migration and invasion, and a slight decrease of cell adhesion. Overexpression of AGR2vH in non-metastatic KKU-213 cells promotes cancer cell migration, invasion, adhesion, and moderate cell proliferation. Moreover, we found that expression of a metastasis-associated gene, vimentin, positively correlates with expression of AGR2vH. Our results support the notion that aberrant alternative splicing of AGR2 facilitates an accumulation of the oncogenic AGR2vH isoform, in turn, contributes to the pathogenesis and severity of CCA.

The Sequence-specific Peptide-binding Activity of the Protein Sulfide Isomerase AGR2 Directs Its Stable Binding to the Oncogenic Receptor EpCAM

AGR2 is an oncogenic endoplasmic reticulum (ER)-resident protein disulfide isomerase. AGR2 protein has a relatively unique property for a chaperone in that it can bind sequence-specifically to a specific peptide motif (TTIYY). A synthetic TTIYY-containing peptide column was used to affinity-purify AGR2 from crude lysates highlighting peptide selectivity in complex mixtures. Hydrogen-deuterium exchange mass spectrometry localized the dominant region in AGR2 that interacts with the TTIYY peptide to within a structural loop from amino acids 131–135 (VDPSL). A peptide binding site consensus of Tx[IL][YF][YF] was developed for AGR2 by measuring its activity against a mutant peptide library. Screening the human proteome for proteins harboring this motif revealed an enrichment in transmembrane proteins and we focused on validating EpCAM as a potential AGR2-interacting protein. AGR2 and EpCAM proteins formed a dose-dependent protein-protein interaction in vitro. Proximity ligation assays demonstrated that endogenous AGR2 and EpCAM protein associate in cells. Introducing a single alanine mutation in EpCAM at Tyr251 attenuated its binding to AGR2 in vitro and in cells. Hydrogen-deuterium exchange mass spectrometry was used to identify a stable binding site for AGR2 on EpCAM, adjacent to the TLIYY motif and surrounding EpCAM's detergent binding site. These data define a dominant site on AGR2 that mediates its specific peptide-binding function. EpCAM forms a model client protein for AGR2 to study how an ER-resident chaperone can dock specifically to a peptide motif and regulate the trafficking a protein destined for the secretory pathway.