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

• MeSH
• gastrointestinální nádory * genetika   MeSH
• karcinogeneze genetika   MeSH
• mukoproteiny genetika   MeSH
• myši MeSH
• nádorové mikroprostředí MeSH
• onkogenní proteiny * genetika   MeSH
• proteindisulfidisomerasy MeSH
• zánět genetika   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• mukoproteiny MeSH
• onkogenní proteiny * MeSH
• proteindisulfidisomerasy MeSH

Anterior gradient 2 (AGR2) is an endoplasmic reticulum (ER)-resident protein disulfide isomerase (PDI) known to be overexpressed in many human epithelial cancers and is involved in cell migration, cellular transformation, angiogenesis, and metastasis. This protein inhibits the activity of the tumor suppressor p53, and its expression levels can be used to predict cancer patient outcome. However, the precise network of AGR2-interacting partners and clients remains to be fully characterized. Herein, we used label-free quantification and also stable isotope labeling with amino acids in cell culture-based LC-MS/MS analyses to identify proteins interacting with AGR2. Functional annotation confirmed that AGR2 and its interaction partners are associated with processes in the ER that maintain intracellular metabolic homeostasis and participate in the unfolded protein response, including those associated with changes in cellular metabolism, energy, and redox states in response to ER stress. As a proof of concept, the interaction between AGR2 and PDIA3, another ER-resident PDI, was studied in more detail. Pathway analysis revealed that AGR2 and PDIA3 play roles in protein folding in ER, including post-translational modification and in cellular response to stress. We confirmed the AGR2-PDIA3 complex formation in cancer cells, which was enhanced in response to ER stress. Accordingly, molecular docking characterized potential quaternary structure of this complex; however, it remains to be elucidated whether AGR2 rather contributes to PDIA3 maturation in ER, the complex directly acts in cellular signaling, or mediates AGR2 secretion. Our study provides a comprehensive insight into the protein-protein interaction network of AGR2 by identifying functionally relevant proteins and related cellular and biochemical pathways associated with the role of AGR2 in cancer cells.

• Klíčová slova
• anterior gradient protein 2, mass spectrometry, protein disulfide isomerase, protein–protein interactions, secretory pathway,
• MeSH
• chromatografie kapalinová MeSH
• lidé MeSH
• mapy interakcí proteinů MeSH
• mukoproteiny * metabolismus   MeSH
• nádory * MeSH
• onkogenní proteiny * metabolismus   MeSH
• proteindisulfidisomerasy * MeSH
• simulace molekulového dockingu MeSH
• tandemová hmotnostní spektrometrie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• AGR2 protein, human MeSH Prohlížeč
• mukoproteiny * MeSH
• onkogenní proteiny * MeSH
• proteindisulfidisomerasy * MeSH

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.

• Klíčová slova
• AGR2, AMPK, ROS, autophagy, colorectal cancer, diabetes mellitus,
• Publikační typ
• časopisecké články MeSH

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

• Klíčová slova
• Src family kinases, Src phosphorylation, adhesion, anterior gradient proteins, cancer, migration, secreted protein disulfide isomerase family,
• Publikační typ
• časopisecké články MeSH

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.

• MeSH
• adhezní molekula epiteliálních buněk genetika   metabolismus   MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• mukoproteiny MeSH
• onkogenní proteiny MeSH
• peptidy metabolismus   MeSH
• proteiny genetika   metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 metabolismus   MeSH
• rekombinantní proteiny metabolismus   MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adhezní molekula epiteliálních buněk MeSH
• AGR2 protein, human MeSH Prohlížeč
• EPCAM protein, human MeSH Prohlížeč
• MDM2 protein, human MeSH Prohlížeč
• mukoproteiny MeSH
• onkogenní proteiny MeSH
• peptidy MeSH
• proteiny MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• rekombinantní proteiny MeSH

The tumor suppressor p53 plays a key role in malignant transformation and tumor development. However, the frequency of p53 mutations within individual types of cancer is different, suggesting the existence of other mechanisms attenuating p53 tumor suppressor activity. Changes in upstream regulators of p53 such as MDM2 amplification and overexpression, expression of viral oncoproteins, estrogen receptor signaling, or changes in p53 transcriptional target genes were previously described in wild-type p53 tumors. We identified a novel pathway responsible for attenuation of p53 activity in human cancers. We demonstrate that AGR2, which is overexpressed in a variety of human cancers and provides a poor prognosis, up-regulates DUSP10 which subsequently inhibits p38 MAPK and prevents p53 activation by phosphorylation. Analysis of human breast cancers reveals that AGR2 specifically provides a poor prognosis in ER+ breast cancers with wild-type p53 but not ER- or mutant p53 breast cancers, and analysis of independent data sets show that DUSP10 levels also have prognostic significance in this specific sub-group of patients. These data not only reveal a novel pro-oncogenic signaling pathway mediating resistance to DNA damaging agents in human tumors, but also has implications for designing alternative strategies for modulation of wild-type p53 activity in cancer therapy.

• Klíčová slova
• AGR2, Breast cancer, DUSP10, Drug resistance, p38 MAPK, p53,
• MeSH
• aktivace enzymů účinky léků   MeSH
• antitumorózní látky farmakologie   MeSH
• chemorezistence MeSH
• dospělí MeSH
• fosfatasy MAP kinas metabolismus   MeSH
• fosfatasy s dvojí specifitou metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mitogenem aktivované proteinkinasy p38 metabolismus   MeSH
• mukoproteiny MeSH
• nádorové buněčné linie MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• nádory farmakoterapie   metabolismus   patologie   MeSH
• onkogenní proteiny MeSH
• proteiny metabolismus   MeSH
• prsy účinky léků   metabolismus   patologie   MeSH
• senioři MeSH
• signální transdukce * účinky léků   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• AGR2 protein, human MeSH Prohlížeč
• antitumorózní látky MeSH
• DUSP10 protein, human MeSH Prohlížeč
• fosfatasy MAP kinas MeSH
• fosfatasy s dvojí specifitou MeSH
• mitogenem aktivované proteinkinasy p38 MeSH
• mukoproteiny MeSH
• nádorový supresorový protein p53 MeSH
• onkogenní proteiny MeSH
• proteiny MeSH

Anterior gradient protein (AGR) 3 is a highly related homologue of pro-oncogenic AGR2 and belongs to the family of protein disulfide isomerases. Although AGR3 was found in breast, ovary, prostate, and liver cancer, it remains of yet poorly defined function in tumorigenesis. This study aimed to determine AGR3 expression in a cohort of 129 primary breast carcinomas and evaluate the clinical and prognostic significance of AGR3 in these tumors. The immunohistochemical analysis revealed the presence of AGR3 staining to varying degrees in 80% of analyzed specimens. The percentage of AGR3-positive cells significantly correlated with estrogen receptor, progesterone receptor (both P<0.0001) as well as low histological grade (P=0.003), and inversely correlated with the level of Ki-67 expression (P<0.0001). In the whole cohort, AGR3 expression was associated with longer progression-free survival (PFS), whereas AGR3-positive subgroup of low-histological grade tumors showed both significantly longer PFS and overall survival. In conclusion, AGR3 is associated with the level of differentiation, slowly proliferating tumors, and more favorable prognosis of breast cancer patients.

• Klíčová slova
• AGR3, ER-positive breast cancer, immuno histochemistry, patient survival, protein disulfide isomerase,
• Publikační typ
• časopisecké články MeSH