Induction of anterior gradient 2 (AGR2) plays a key role in insulin-like growth factor-1 (IGF-1)-induced breast cancer cell proliferation and migration

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Construction and stable gene expression of AGR2xPD1 bi-specific antibody that enhances attachment between T-Cells and lung tumor cells, suppress tumor cell migration and promoting CD8 expression in cytotoxic T-cells

There has been a substantial and consistent rise in the number of clinical trials to develop advanced and potent bispecific antibodies (BsAb) over the past two decades with multiple targets to improve the efficacy or tissue specificity of monoclonal antibodies (mAb) treatment for diseases with multiple determining factors or widely-expressed targets. In this study, we designed and synthesized BsAb AGR2xPD1 targeting extracellular AGR2, a paracrine signal, and PD1, an immune checkpoint protein. Our design is intended to use AGR2 binding to guide PD1 targeting for AGR2⁺cancer. We used this construction to produce AGR2xPD1 BsAb by generating clonally selected stable 293F cell line with high expression. Applying this BsAb in a T cell-Tumor cell co-culture system showed that targeting both PD1 and AGR2 with this BsAb induces the attachment of TALL-104 (CD8⁺ T-lymphocytes) cells onto co-cultured H460 AGR2⁺ Lung tumor cells and significantly reduces migration of H460 cells. T-cell expression of CD8 and IFNγ is also synergistically enhanced by the AGR2xPD1 BsAb treatment in the AGR2⁺H460 co-culture system. These effects are significantly reduced with AGR2 expression negative WI38 cells. Our results demonstrate that the AGR2xPD1 BsAb could be a potential therapeutic agent to provide better solid tumor targeting and synergetic efficacy for treating AGR2+ cancer by blocking AGR2 paracrine signaling to reduce tumor survival, and redirecting cytotoxic T-cells into AGR2+ cancer cells.

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.

Expression of KAI1 and AGR2 in lung adenocarcinoma and their clinicopathological significance

OBJECTIVE

Anticancer 1 (KAI1, tumor metastasis suppressor gene) and Anterior gradient-2 (AGR2, considered a valuable prognostic factor for some cancers) are associated with metastasis and prognosis of various types of human cancers. Nevertheless, the relationship between KAI1 and AGR2 in lung adenocarcinoma (LUAD) remains unclear. In this research, we analyzed the correlations between KAI1 and AGR2 in LUAD, and explored their correlations with clinicopathological parameters and overall survival time (OS) in patients with LUAD.

METHODS

Immunohistochemical staining was used to detect KAI1 and AGR2 expression in 132 cases of LUAD samples. At the same time, all clinicopathological parameters and postoperative survival information were collected.

RESULTS

AGR2 positive rate was significantly increased and KAI1 positive rate was significantly decreased in LUAD and control tissues. KAI1 positive rates were negatively correlated with tumor stage, LNM stage and TNM stage, and KAI1 subgroup positive expression of OS was significantly higher than negative KAI1 subgroup. The positive rate of AGR2 was positively correlated with tumor grade, LNM stage and TNM stage, and negatively correlated with patients OS. Active expression of AGR2 and KAI1, tumor stage, and LNM stage in multivariate analyses may be independent prognostic factors for OS in LUAD patients.

CONCLUSION

KAI1 and AGR2 may be potential biomarkers for prognosis and metastasis, and they are also promising therapeutic targets for LUAD patients.

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.

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

Simple Summary

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

Abstract

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

Secretion of pro-oncogenic AGR2 protein in cancer

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

AGR3 promotes estrogen receptor-positive breast cancer cell proliferation in an estrogen-dependent manner

Breast cancer is one of the most common malignancies and the leading cause of cancer-associated death among women. Anterior gradient 3 (AGR3) is a cancer-associated gene and is similar to its homologous oncogene AGR2. However, whether AGR3 participates in breast cancer progression remains unclear. The present study aimed to investigate the function of AGR3 in ER-positive breast cancer. In the present study, reverse transcription-quantitative PCR was used to detect AGR3 mRNA expression in breast cancer tissues and cell lines; linear correlation analysis was used to investigate the correlation between AGR3 and estrogen receptor 1 (ESR1) expression in breast cancer via GEO dataset analysis; western blotting was used to assess the levels of AGR3, ER and GAPDH; small interfering (si)RNA transfection was used to knock down AGR3 and ESR1 expression; and finally the Cell Counting Kit-8 assay was used to evaluate cell viability. In the present study, AGR3 expression was markedly increased in estrogen receptor (ER)-positive breast cancer tissues and cell lines compared with that in ER-negative breast cancer. AGR3 expression was upregulated in estrogen-treated T47D cells, whereas 4-hydroxytamoxifen, an inhibitor of estrogen-ER activity in breast cancer cells, downregulated AGR3 expression in T47D cells. Functional assays demonstrated that knockdown of AGR3 using siRNAs inhibited T47D cell proliferation compared with that of the negative control group. Additionally, AGR3 expression was decreased after knocking down ESR1. The present results suggested that AGR3 may serve an important role in estrogen-mediated cell proliferation in breast cancer and that AGR3 knockdown may be a potential therapeutic strategy for ER-positive breast cancer.

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

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

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.

Knockdown of AGR2 induces cell apoptosis and reduces chemotherapy resistance of pancreatic cancer cells with the involvement of ERK/AKT axis

BACKGROUND

Pancreatic cancer (PC), an aggressive human malignancy, presents with a striking resistance to chemotherapy. Interesting, AGR2 has been found to be upregulated in various cancers and has been found to promote the dissemination of PC cells. Thereby, a series of in-vitro experiments were performed to investigate the relationship between AGR2 and the ERK/AKT axis, and to explore whether it affects PC cells.

METHODS

Positive expression of AGR2 protein in the PC and paracancerous tissues collected from 138 patients with PC was detected using immunohistochemistry. After treatment with FGF2 (an ERK/AKT axis agonist), siRNA against AGR2 or their combination respectively, cell viability, chemotherapy resistance, radiotherapy resistance, migration, invasion and apoptosis in PC cells were detected using CCK8 assay, MTT assay, clone formation assay, wound healing assay, Transwell assay and flow cytometry, respectively. The expressions of AGR2 and ERK/AKT axis-related genes and proteins in tissues and cells were detected using reverse transcription quantitative polymerase chain reaction and Western blot assay.

RESULTS

PC tissues exhibited highly-expressed AGR2 and abnormally activated ERK/AKT axis. FGF2 promoted the expression of AGR2, ERK/AKT axis activation, cell viability, chemotherapy resistance, migration and invasion, but decreased cell apoptosis in PC cells. However, knockdown of AGR2 resulted in inhibition of the ERK/AKT axis, reduced PC cell viability, chemotherapy resistance, migration and invasion but increased cell apoptosis in PC cells.

CONCLUSION

The findings reveal that AGR2 silencing could promote cell apoptosis and inhibit cell migration, invasion and chemotherapy resistance of PC cell with the involvement of the ERK/AKT axis.

Association of increased primary breast tumor AGR2 with decreased disease-specific survival

Objective

Tumor expression of Anterior Gradient 2 (AGR2), an endoplasmic reticulum protein disulfide isomerase, was associated with decreased breast cancer survival. We aimed to validate the association of tumor AGR2 mRNA expression with disease-specific survival (DSS) and identify differentially expressed signaling pathways between high and low AGR2 expression tumor groups.

Methods

Primary tumor mRNA expression data from the METABRIC study was used to evaluate AGR2 expression as a prognostic factor for DSS while adjusting for survival-determining confounders using Cox proportional-hazards regression. Differentially expressed genes and signaling pathway differences between high and low AGR2 groups were determined by modular enrichment analyses using DAVID and Ingenuity Pathway Analysis.

Results

Increased tumor AGR2 mRNA expression was associated with decreased DSS among 1,341 women (per each standard deviation increase of AGR2 expression: HR 1.14, 95% CI: 1.01-1.29, P = 0.03). Pathway analyses supported prior experimental studies showing that estrogen receptor 1 (ESR1) regulated AGR2 expression. Canonical signaling pathways significantly differentially represented between high and low AGR2 groups included those involved in inflammation and immunity.

Conclusion

Increased primary tumor AGR2 expression was associated with decreased DSS. Pathway analyses suggested that increased AGR2 was associated with endoplasmic reticular homeostasis, possibly allowing tumor cells to overcome hypoxic stress and meet the increased protein demand of tumorigenesis, thereby preventing unfolded protein response-mediated apoptosis.

Associations of MACC1, AGR2, and KAI1 expression with the metastasis and prognosis in head and neck squamous cell carcinoma

BACKGROUND

Metastasis-associated in colon cancer-1 (MACC1, was firstly found in colon cancer and associated metastasis and prognosis in various cancers), anterior gradient 2 (AGR2, was considered as a valuable prognostic factor for some cancers), and Kangai 1 (KAI1, was a tumor metastasis suppressor gene) are all related to metastasis and prognosis of many cancers. However, the associations of MACC1, AGR2, and KAI1 in head and neck squamous cell carcinoma (HNSCC) are still unclear. In this study, we analyzed associations among MACC1, AGR2, and KAI1 in HNSCC, and their respective associations with clinicopathological parameters and overall survival (OS) in HNSCC.

METHODS

Positive expression of MACC1, AGR2, and KAI1 in 106 whole HNSCC tissue samples was detected by immunohistochemical staining. Patient's clinical data and demographics were both collected.

RESULTS

Positive rates of MACC1 and AGR2 were significantly higher, and positive rate of KAI1 was significantly lower, in HNSCC and than those in control tissues. Positive rates of MACC1 and AGR2 were positively correlated with grades of tumor, TNM stages, and lymph node metastasis (LNM) stages, and negatively with patients OS; positive rate of KAI1 was negatively associated with grades of tumor, TNM stages, and LNM stages, and the positive expression of KAI1 subgroup had significantly longer OS than did the negative KAI1 subgroup. In multivariate analysis, positive expression MACC1, AGR2, and KAI1, and tumor stages, as well as LNM stages were potential to be independent prognostic factors for OS in patients with HNSCC.

CONCLUSIONS

MACC1, AGR2, and KAI1 may represent potential metastatic and prognostic biomarkers, as well as promising therapeutic targets for HNSCC.

Pro-metastatic activity of AGR2 interrupts angiogenesis target bevacizumab efficiency via direct interaction with VEGFA and activation of NF-κB pathway

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.

Suppression of AGR2 in a TGF-β-induced Smad regulatory pathway mediates epithelial-mesenchymal transition

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.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3537-5) contains supplementary material, which is available to authorized users.

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

Anterior gradient 2 (AGR2), a member of protein disulfide isomerase (PDI) family, is both located in cytoplasm and secreted into extracellular matrix. The orthologs of AGR2 have been linked to limb regeneration in newt and wound healing in zebrafish. In mammals, AGR2 influences multiple cell signaling pathways in tumor formation and in normal cell functions related to new tissue formation like angiogenesis. However, the function of AGR2 in mammalian wound healing remains unknown. This study aimed to investigate AGR2 expression and its function during skin wound healing and the possible application of external AGR2 in cutaneous wound to accelerate the healing process. Our results showed that AGR2 expression was induced in the migrating epidermal tongue and hyperplastic epidermis after skin excision. Topical application of recombinant AGR2 significantly accelerated wound-healing process by increasing the migration of keratinocytes (Kera.) and the recruitment of fibroblasts (Fibro.) near the wounded area. External AGR2 also promoted the migration of Kera. and Fibro. in vitro in a dose-dependent manner. The adhesion domain of AGR2 was required for the formation of focal adhesions in migrating Fibro., leading to the directional migration along AGR2 gradient. These results indicate that recombinant AGR2 accelerates skin wound healing through regulation of Kera. and Fibro. migration, thus demonstrating its potential utility as an alternative strategy of the therapeutics to accelerate the healing of acute or chronic skin wounds.

Regulation of AGR2 expression via 3'UTR shortening

One recently discussed general mechanism affecting gene expression is 3'-untranslated region (3'UTR) length. Events such as shortening, translocation or loss of 3'UTRs are observed within oncogenes and are proposed to associate with increased expression. Thus, increased efforts are being made to understand constitutive and differential transcript 3'end formation. Investigation of AGR2 mRNA revealed a direct impact of its 3'UTR length on AGR2 expression. In silico analyses identified several regulatory sequences within the distal part of AGR2 mRNA that may regulate 3'UTR length and associated protein levels. Short 3'UTRs were observed in a panel of AGR2-positive cancer cell lines and in human breast cancer specimens, in which more extensive 3'UTR shortening correlated with increased AGR2 protein levels. AGR2 is an important member of PI3K/AKT signalling pathway, which along with the proposed involvement of mTOR in the regulation of alternative polyadenylation, prompted us to study the role of mTOR in relation to AGR2 mRNA 3'UTR shortening. A direct impact of mTOR signalling on AGR2 3'UTR shortening associated with increased protein synthesis was found, which led to the identification of a novel molecular mechanism involved in upregulation of AGR2 levels in mTOR-activated cells via modulating the 3'UTR length of AGR2 mRNA.

Translational Research and Plasma Proteomic in Cancer

Proteomics is a recent field of research in molecular biology that can help in the fight against cancer through the search for biomarkers that can detect this disease in the early stages of its development. Proteomic is a speedily growing technology, also thanks to the development of even more sensitive and fast mass spectrometry analysis. Although this technique is the most widespread for the discovery of new cancer biomarkers, it still suffers of a poor sensitivity and insufficient reproducibility, essentially due to the tumor heterogeneity. Common technical shortcomings include limitations in the sensitivity of detecting low abundant biomarkers and possible systematic biases in the observed data. Current research attempts are trying to develop high-resolution proteomic instrumentation for high-throughput monitoring of protein changes that occur in cancer. In this review, we describe the basic features of the proteomic tools which have proven to be useful in cancer research, showing their advantages and disadvantages. The application of these proteomic tools could provide early biomarkers detection in various cancer types and could improve the understanding the mechanisms of tumor growth and dissemination.

Milk--A Nutrient System of Mammalian Evolution Promoting mTORC1-Dependent Translation

Based on own translational research of the biochemical and hormonal effects of cow's milk consumption in humans, this review presents milk as a signaling system of mammalian evolution that activates the nutrient-sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), the pivotal regulator of translation. Milk, a mammary gland-derived secretory product, is required for species-specific gene-nutrient interactions that promote appropriate growth and development of the newborn mammal. This signaling system is highly conserved and tightly controlled by the lactation genome. Milk is sufficient to activate mTORC1, the crucial regulator of protein, lipid, and nucleotide synthesis orchestrating anabolism, cell growth and proliferation. To fulfill its mTORC1-activating function, milk delivers four key metabolic messengers: (1) essential branched-chain amino acids (BCAAs); (2) glutamine; (3) palmitic acid; and (4) bioactive exosomal microRNAs, which in a synergistical fashion promote mTORC1-dependent translation. In all mammals except Neolithic humans, postnatal activation of mTORC1 by milk intake is restricted to the postnatal lactation period. It is of critical concern that persistent hyperactivation of mTORC1 is associated with aging and the development of age-related disorders such as obesity, type 2 diabetes mellitus, cancer, and neurodegenerative diseases. Persistent mTORC1 activation promotes endoplasmic reticulum (ER) stress and drives an aimless quasi-program, which promotes aging and age-related diseases.