S100A6 as a potential serum prognostic biomarker and therapeutic target in gastric cancer

S100a6 knockdown promotes the differentiation of dental epithelial cells toward the epidermal lineage instead of the odontogenic lineage

Tooth development is a complex process involving various signaling pathways and genes. Recent findings suggest that ion channels and transporters, including the S100 family of calcium-binding proteins, may be involved in tooth formation. However, our knowledge in this regard is limited. Therefore, this study aimed to investigate the expression of S100 family members and their functions during tooth formation. Tooth germs were extracted from the embryonic and post-natal mice and the expression of S100a6 was examined. Additionally, the effects of S100a6 knockdown and calcium treatment on S100a6 expression and the proliferation of SF2 cells were examined. Microarrays and single-cell RNA-sequencing indicated that S100a6 was highly expressed in ameloblasts. Immunostaining of mouse tooth germs showed that S100a6 was expressed in ameloblasts but not in the undifferentiated dental epithelium. Additionally, S100a6 was localized to the calcification-forming side in enamel-forming ameloblasts. Moreover, siRNA-mediated S100a6 knockdown in ameloblasts reduced intracellular calcium concentration and the expression of ameloblast marker genes, indicating that S100a6 is associated with ameloblast differentiation. Furthermore, S100a6 knockdown inhibited the ERK/PI3K signaling pathway, suppressed ameloblast proliferation, and promoted the differentiation of the dental epithelium toward epidermal lineage. Conclusively, S100a6 knockdown in the dental epithelium suppresses cell proliferation via calcium and intracellular signaling and promotes differentiation of the dental epithelium toward the epidermal lineage.

S100A6: molecular function and biomarker role

S100A6 (also called calcyclin) is a Ca2+-binding protein that belongs to the S100 protein family. S100A6 has many functions related to the cytoskeleton, cell stress, proliferation, and differentiation. S100A6 also has many interacting proteins that are distributed in the cytoplasm, nucleus, cell membrane, and outside the cell. Almost all these proteins interact with S100A6 in a Ca2+-dependent manner, and some also have specific motifs responsible for binding to S100A6. The expression of S100A6 is regulated by several transcription factors (such as c-Myc, P53, NF-κB, USF, Nrf2, etc.). The expression level depends on the specific cell type and the transcription factors activated in specific physical and chemical environments, and is also related to histone acetylation, DNA methylation, and other epigenetic modifications. The differential expression of S100A6 in various diseases, and at different stages of those diseases, makes it a good biomarker for differential diagnosis and prognosis evaluation, as well as a potential therapeutic target. In this review, we mainly focus on the S100A6 ligand and its transcriptional regulation, molecular function (cytoskeleton, cell stress, cell differentiation), and role as a biomarker in human disease and stem cells.

Interaction of S100A6 Protein with the Four-Helical Cytokines

S100 is a family of over 20 structurally homologous, but functionally diverse regulatory (calcium/zinc)-binding proteins of vertebrates. The involvement of S100 proteins in numerous vital (patho)physiological processes is mediated by their interaction with various (intra/extra)cellular protein partners, including cell surface receptors. Furthermore, recent studies have revealed the ability of specific S100 proteins to modulate cell signaling via direct interaction with cytokines. Previously, we revealed the binding of ca. 71% of the four-helical cytokines via the S100P protein, due to the presence in its molecule of a cytokine-binding site overlapping with the binding site for the S100P receptor. Here, we show that another S100 protein, S100A6 (that has a pairwise sequence identity with S100P of 35%), specifically binds numerous four-helical cytokines. We have studied the affinity of the recombinant forms of 35 human four-helical cytokines from all structural families of this fold to Ca2+-loaded recombinant human S100A6, using surface plasmon resonance spectroscopy. S100A6 recognizes 26 of the cytokines from all families of this fold, with equilibrium dissociation constants from 0.3 nM to 12 µM. Overall, S100A6 interacts with ca. 73% of the four-helical cytokines studied to date, with a selectivity equivalent to that for the S100P protein, with the differences limited to the binding of interleukin-2 and oncostatin M. The molecular docking study evidences the presence in the S100A6 molecule of a cytokine-binding site, analogous to that found in S100P. The findings argue the presence in some of the promiscuous members of the S100 family of a site specific to a wide range of four-helical cytokines. This unique feature of the S100 proteins potentially allows them to modulate the activity of the numerous four-helical cytokines in the disorders accompanied by an excessive release of the cytokines.

The Role of S100A6 in Human Diseases: Molecular Mechanisms and Therapeutic Potential

S100A6, also known as calcyclin, is a low-molecular-weight Ca2+-binding protein from the S100 family that contains two EF-hands. S100A6 is expressed in a variety of mammalian cells and tissues. It is also expressed in lung, colorectal, pancreatic, and liver cancers, as well as other cancers such as melanoma. S100A6 has many molecular functions related to cell proliferation, the cell cycle, cell differentiation, and the cytoskeleton. It is not only involved in tumor invasion, proliferation, and migration, but also the pathogenesis of other non-neoplastic diseases. In this review, we focus on the molecular mechanisms and potential therapeutic targets of S100A6 in tumors, nervous system diseases, leukemia, endometriosis, cardiovascular disease, osteoarthritis, and other related diseases.

Gene Regulatory Network-Classifier: Gene Regulatory Network-Based Classifier and Its Applications to Gastric Cancer Drug (5-Fluorouracil) Marker Identification

The complex mechanisms of diseases involve the disturbance of the molecular network, rather than disorder in a single gene, implying that single gene-based analysis is insufficient to understand these mechanisms. Gene regulatory networks (GRNs) have attracted a lot of interest and various approaches have been developed for their statistical inference and gene network-based analysis. Although various computational methods have been developed, relatively little attention has been paid to incorporation of biological knowledge into the computational approaches. Furthermore, existing studies on network-based analysis perform prediction/classification of status of cell lines based on preconstructed GRNs, implying that we cannot extract prediction/classification-specific gene networks, leading to difficulty in interpretation of biological mechanisms and marker identification related to the status of cancer cell lines. We developed a novel strategy to build a GRN-based classifier, called a GRN-classifier. The proposed GRN-classifier estimates GRNs and classifies cell lines simultaneously, where the gene network is estimated to minimize error in gene network estimation and the negative log-likelihood for classifying cell lines. Thus, we can identify biological status-specific gene regulatory systems, enabling us to achieve biologically reliable interpretation of the classification. We also propose an algorithm to implement the GRN-classifier based on coordinate descent update. Monte Carlo simulations were conducted to examine performance of the GRN-classifier. Results: Our strategy provides effective results in feature selection in the classification model and edge selection in gene network estimation. The GRN-classifier also shows outstanding classification accuracy. We apply the GRN-classifier to classify cancer cell lines into anticancer drug-related status, that is, 5-fluorouracil (5-FU)-sensitive/resistant and 5-FU target/nontarget cancer cell lines. We then identified 5-FU markers based on 5-FU-related status classification-specific gene networks. The mechanisms of the identified markers were verified through literature survey. Our results suggest that the molecular interplay between MYOF and AHNAK2 may play a crucial role in drug resistance and can provide information on the chemotherapy efficiency of 5-FU. It is also suggested that suppression of the identified 5-FU markers, including MYOF/AHNAK2 and AKR1C1/AKR1C3 may improve 5-FU resistance of cancer cell lines.

S100A6 Protein-Expression and Function in Norm and Pathology

S100A6, also known as calcyclin, is a calcium-binding protein belonging to the S100 protein family. It was first identified and purified more than 30 years ago. Initial structural studies, focused mostly on the mode and affinity of Ca²⁺ binding and resolution of the resultant conformational changes, were soon complemented by research on its expression, localization and identification of binding partners. With time, the use of biophysical methods helped to resolve the structure and versatility of S100A6 complexes with some of its ligands. Meanwhile, it became clear that S100A6 expression was altered in various pathological states and correlated with the stage/progression of many diseases, including cancers, indicative of its important, and possibly causative, role in some of these diseases. This, in turn, prompted researchers to look for the mechanism of S100A6 action and to identify the intermediary signaling pathways and effectors. After all these years, our knowledge on various aspects of S100A6 biology is robust but still incomplete. The list of S100A6 ligands is growing all the time, as is our understanding of the physiological importance of these interactions. The present review summarizes available data concerning S100A6 expression/localization, interaction with intracellular and extracellular targets, involvement in Ca²⁺-dependent cellular processes and association with various pathologies.

S100 Proteins as Novel Therapeutic Targets in Psoriasis and Other Autoimmune Diseases

Psoriasis is one of the most common inflammatory skin diseases affecting about 1-3% of the population. One of the characteristic abnormalities in psoriasis is the excessive production of antimicrobial peptides and proteins, which play an essential role in the pathogenesis of the disease. Antimicrobial peptides and proteins can be expressed differently in normal and diseased skin, reflecting their usefulness as diagnostic biomarkers. Moreover, due to their very important functions in innate immunity, members of host defense peptides and proteins are currently considered to be promising new therapeutic targets for many inflammatory diseases. Koebnerisin (S100A15) belongs to an S100 family of antimicrobial proteins, which constitute the multigenetic group of calcium-binding proteins involved in ion-dependent cellular functions and regulation of immune mechanisms. S100A15 was first discovered to be overexpressed in 'koebnerized' psoriatic skin, indicating its involvement in the disease phenotype and the same promising potential as a new therapeutic target. This review describes the involvement of antimicrobial peptides and proteins in inflammatory diseases' development and therapy. The discussion focuses on S100 proteins, especially koebnerisin, which may be involved in the underlying mechanism of the Köebner phenomenon in psoriasis, as well as other immune-mediated inflammatory diseases described in the last decade.

Curcuminoids as Modulators of EMT in Invasive Cancers: A Review of Molecular Targets With the Contribution of Malignant Mesothelioma Studies

Curcuminoids, which include natural acyclic diarylheptanoids and the synthetic analogs of curcumin, have considerable potential for fighting against all the characteristics of invasive cancers. The epithelial-to-mesenchymal transition (EMT) is a fundamental process for embryonic morphogenesis, however, the last decade has confirmed it orchestrates many features of cancer invasiveness, such as tumor cell stemness, metabolic rewiring, and drug resistance. A wealth of studies has revealed EMT in cancer is in fact driven by an increasing number of parameters, and thus understanding its complexity has now become a cornerstone for defining future therapeutic strategies dealing with cancer progression and metastasis. A specificity of curcuminoids is their ability to target multiple molecular targets, modulate several signaling pathways, modify tumor microenvironments and enhance the host’s immune response. Although the effects of curcumin on these various parameters have been the subject of many reviews, the role of curcuminoids against EMT in the context of cancer have never been reviewed so far. This review first provides an updated overview of all EMT drivers, including signaling pathways, transcription factors, non-coding RNAs (ncRNAs) and tumor microenvironment components, with a special focus on the most recent findings. Secondly, for each of these drivers the effects of curcumin/curcuminoids on specific molecular targets are analyzed. Finally, we address some common findings observed between data reported in the literature and the results of investigations we conducted on experimental malignant mesothelioma, a model of invasive cancer representing a useful tool for studies on EMT and cancer.

Analysis at the single-cell level indicates an important role of heterogeneous global DNA methylation status on the progression of lung adenocarcinoma

Aberrant DNA modifications affect the tumorigenesis and progression of lung cancer. However, the global methylation status of tumor cells and the heterogeneous methylation status of cells within the same tumor need further study. We used publicly available single-cell RNAseq data to investigate the impact and diversity of global methylation status on lung adenocarcinoma. Clustering cells into subgroups and cell differentiation pseudotime analysis, based on expression profile, demonstrated that the global methylation status was crucial to lung adenocarcinoma function and progression. Hypermethylated tumor cells had increased activity related to the hypoxia response. Hyper- and hypomethylated cells indicated upregulation in pathways involving focal adhesion and cell junctions. Pseudotime analysis showed that cell clusters with unique methylation activities were located at the ends of the putative trajectories, suggesting that DNA methylation and demethylation activities were essential to tumor cell progression. Expression of SPP1 was associated with the global methylation status of tumor cells and with patient prognosis. Our study identified the importance and diversity of global DNA methylation status by analysis at the single-cell level. Our findings provide new information about the global DNA methylation status of tumor cells and suggest new approaches for precision medical treatments for lung adenocarcinoma.

Knockdown of ferritin heavy chain (FTH) inhibits the migration of prostate cancer through reducing S100A4, S100A2, and S100P expression

BACKGROUND

Ferritin plays a key role in the development of prostate cancer (PCa). Our earlier studies showed that the knockdown of ferritin heavy chain (FTH) suppressed the migration and invasion of the prostate cancer cell line (PC3). However, the mechanisms behind FTH in the cell migration regulation of PCa have not been thoroughly investigated.

METHODS

Isobaric tags for relative and absolute quantitation (iTRAQ) proteomics was used to analyze the protein expression in PC3 cells with FTH knockdown by small interfering RNAs and negative control cells. We subsequently ranked the differentially expressed proteins according to the change in expression. We further performed Gene Ontology (GO) analysis for the changing-expression protein. Finally, Western blot analysis was performed to determine the expression of the target protein.

RESULTS

Compared with the negative group, 420 proteins were downregulated, including proteins S100A4, S100P, and S100A2, while the expression of 442 protein was elevated in FTH-silencing PC3 cells (P<0.05, fold change >1.2). The mass spectrometry results showing decreased expression of protein S100A4, S100P, and S100A2 in the cells were further validated by Western blot (P<0.05). Levels of protein S100A4, S100A2, and S100P were reduced in FTH-silencing PC3 cells (P<0.05, fold change >1.6).

CONCLUSIONS

The downregulation of FTH expression reduced the level of protein S100A4, S100A2, and S100P, which all play a key role in the migration and invasion of tumor cells. Therefore, it is reasonable to assume that there are correlations between the expression of the S100A4, S100A2, and S100P genes with FTH. Based on this research, FTH may be a new biomarker for the diagnosis of PCa.

Biomarkers of tumor invasiveness in proteomics (Review)

Over the past two decades, quantitative proteomics has emerged as an important tool for deciphering the complex molecular events involved in cancers. The number of references involving studies on the cancer metastatic process has doubled since 2010, while the last 5 years have seen the development of novel technologies combining deep proteome coverage capabilities with quantitative consistency and accuracy. To highlight key findings within this huge amount of information, the present review identified a list of tumor invasive biomarkers based on both the literature and data collected on a biocollection of experimental cell lines, tumor models of increasing invasiveness and tumor samples from patients with colorectal or breast cancer. Crossing these different data sources led to 76 proteins of interest out of 1,245 mentioned in the literature. Information on these proteins can potentially be translated into clinical prospects, since they represent potential targets for the development and evaluation of innovative therapies, alone or in combination. Herein, a systematical review of the biology of each of these proteins, including their specific subcellular/extracellular or multiple localizations is presented. Finally, as an important advantage of quantitative proteomics is the ability to provide data on all these molecules simultaneously in cell pellets, body fluids or paraffin‑embedded sections of tumors/invaded tissues, the significance of some of their interconnections is discussed.

Role of S100 proteins in health and disease

The S100 family of proteins contains 25 known members that share a high degree of sequence and structural similarity. However, only a limited number of family members have been characterized in depth, and the roles of other members are likely undervalued. Their importance should not be underestimated however, as S100 family members function to regulate a diverse array of cellular processes including proliferation, differentiation, inflammation, migration and/or invasion, apoptosis, Ca²⁺ homeostasis, and energy metabolism. Here we detail S100 target protein interactions that underpin the mechanistic basis to their function, and discuss potential intervention strategies targeting S100 proteins in both preclinical and clinical situations.

Serum S100A6, S100A8, S100A9 and S100A11 proteins in colorectal neoplasia: results of a single centre prospective study

S100 proteins are involved in biological events related to colorectal carcinogenesis. Aim of this prospective study was to assess serum concentration of S100A6, A8, A9 and A11 proteins in patients with colorectal neoplasia. Eighty-four subjects were enrolled: 20 controls (average risk population with normal findings on colonoscopy; 7 men, 13 women, age 23-74, mean 55 ± 14), 20 patients with non-advanced colorectal adenoma (non-AA, 10 men, 10 women, age 41-82, mean 62 ± 11), 22 with advanced colorectal adenoma (AA, 15 men, 7 women, age 49-80, mean 64 ± 8) and 22 with colorectal cancer (CRC, 12 men, 10 women, age 49-86, mean 69 ± 10). Peripheral venous blood was obtained. Serum S100 proteins were investigated by enzyme immunoassay technique. Serum S100A6 was significantly lower in CRC (mean 8530 ± 4743 ng/L), p = .035 compared to controls (mean 11308 ± 2968 ng/L). Serum S100A8 was significantly higher in AA (median 11955 ng/L, IQR 2681-34756 ng/L), p = .009 and in CRC (median 27532 ng/L, IQR 6794-35092 ng/L), p < .001 compared to controls (median 2513 ng/L, IQR 2111-4881 ng/L). Serum S100A9 concentrations did not differ between any tested group and controls, p > .05. Serum concentration of S100A11 was significantly lower in non-AA (mean 3.5 ± 2.4 μg/L), p = .004 and in CRC (mean 3.4 ± 2.4 μg/L), p = .002 compared to controls (mean 5.9 ± 2.5 μg/L). Sensitivity and specificity for S100A8 protein in patients with CRC were 94% and 73%; positive predictive value 68% and negative predictive value 95%. Patients with colorectal neoplasia have significantly lower serum S100A6 and S100A11 levels, significantly higher S100A8 and unaltered serum S100A9 levels.

Monomeric state of S100P protein: Experimental and molecular dynamics study

S100 proteins constitute a large subfamily of the EF-hand superfamily of calcium binding proteins. They possess one classical EF-hand Ca²⁺-binding domain and an atypical EF-hand domain. Most of the S100 proteins form stable symmetric homodimers. An analysis of literature data on S100 proteins showed that their physiological concentrations could be much lower than dissociation constants of their dimeric forms. It means that just monomeric forms of these proteins are important for their functioning. In the present work, thermal denaturation of apo-S100P protein monitored by intrinsic tyrosine fluorescence has been studied at various protein concentrations within the region from 0.04-10 μM. A transition from the dimeric to monomeric form results in a decrease in protein thermal stability shifting the mid-transition temperature from 85 to 75 °C. Monomeric S100P immobilized on the surface of a sensor chip of a surface plasmon resonance instrument forms calcium dependent 1 to 1 complexes with human interleukin-11 (equilibrium dissociation constant 1.2 nM). In contrast, immobilized interleukin-11 binds two molecules of dimeric S100P with dissociation constants of 32 nM and 288 nM. Since effective dissociation constant of dimeric S100P protein is very low (0.5 μM as evaluated from our data) the sensitivity of the existing physical methods does not allow carrying out a detailed study of S100P monomer properties. For this reason, we have used molecular dynamics methods to evaluate structural changes in S100P upon its transition from the dimeric to monomeric state. 80-ns molecular dynamics simulations of kinetics of formation of S100P, S100B and S100A11 monomers from the corresponding dimers have been carried out. It was found that during the transition from the homo-dimer to monomer form, the three S100 monomer structures undergo the following changes: (1) the helices in the four-helix bundles within each monomer rotate in order to shield the exposed non-polar residues; (2) almost all lost contacts at the dimer interface are substituted with equivalent and newly formed interactions inside each monomer, and new stabilizing interactions are formed; and (3) all monomers recreate functional hydrophobic cores. The results of the present study show that both dimeric and monomeric forms of S100 proteins can be functional.

Hepatocellular Carcinoma Outcome Is Predicted by Expression of Neuronal Calcium Sensor 1

Background: Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide. There is an urgent demand for prognostic biomarkers that facilitate early tumor detection, as the incidence of HCC has tripled in the United States in the last three decades. Biomarkers to identify populations at risk would have significant impact on survival. We recently found that expression of Neuronal Calcium Sensor 1 (NCS1), a Ca2+-dependent signaling molecule, predicted disease outcome in breast cancer, but its predictive value in other cancer types is unknown. This protein is potentially useful because increased NCS1 regulates Ca2+ signaling and increased Ca2+ signaling is a hallmark of metastatic cancers, conferring cellular motility and an increasingly aggressive phenotype to tumors.Methods: We explored the relationship between NCS1 expression levels and patient survival in two publicly available liver cancer cohorts and a tumor microarray using data mining strategies.Results: High NCS1 expression levels are significantly associated with worse disease outcome in Asian patients within these cohorts. In addition, a variety of Ca2+-dependent and tumor growth-promoting genes are transcriptionally coregulated with NCS1 and many of them are involved in cytoskeleton organization, suggesting that NCS1 induced dysregulated Ca2+ signaling facilitates cellular motility and metastasis.Conclusions: We found NCS1 to be a novel biomarker in HCC. Furthermore, our study identified a pharmacologically targetable signaling complex that can influence tumor progression in HCC.Impact: These results lay the foundation for using NCS1 as a prognostic biomarker in prospective cohorts of HCC patients and for further functional assessment of the characterized signaling axis. Cancer Epidemiol Biomarkers Prev; 27(9); 1091-100. ©2018 AACR.

S100B as an Antagonist To Interfere with the Interface Area Flanked by S100A11 and RAGE V Domain

The Ca²⁺-sensing protein S100A11 of the S100 family is an important mediator of numerous biological functions and pathological conditions including cancer. The receptor for advanced glycation end products (RAGE) has been well accepted as the major receptor for several S100 family members. Here, we take the S100B protein as an antagonist to interfere with the interaction flanked by S100A11 and the RAGE V domain. We employed NMR spectroscopy to describe the interactions between the S100A11 and S100B proteins. ¹H-¹⁵N heteronuclear single-quantum correlation-NMR titrations showed the potential binding dynamics of S100A11 and S100B interactions. In the HADDOCK program, we constructed the S100A11-S100B heterodimer complex that was then superimposed with the S100A11-S100B complex structure in the same orientation as the S100A11-RAGE V domain complex. This overlay analysis showed that S100B could interfere in the binding section of S100A11 and the RAGE V domain. Additionally, water-soluble tetrazolium-1 assay provided a functional read-out of the effects of these proteins in an in vitro cancer model. Our study establishes that the development of an S100B antagonist could perform a vital part in the treatment of S100- and RAGE-dependent human diseases.

Identification of differentially expressed proteins in the gastric mucosal atypical hyperplasia tissue microenvironment

In the present study, the interaction of proteins in the microenvironment of gastric mucosal atypical hyperplasia was analyzed. The stromata of normal gastric mucosa (NGM) and gastric mucosal atypical hyperplasia (GMAH) tissues were purified with laser capture microdissection (LCM). The differentially expressed GMAH proteins of the NGM and GMAH tissues were identified by quantitative proteomic techniques with isotope labeling. The cross-talk between differentially expressed proteins in NGM and GMAH tissues was then analyzed by bioinformatics. There were 165 differentially expressed proteins identified from the stromata of NGM and GMAH tissues. Among them, 99 proteins were upregulated and 66 were downregulated in GMAH tissue. The present study demonstrated that these proteins in gastric mucosal atypical hyperplasia were involved in cancer-associated signaling pathways, including the p53, mitogen-activated protein kinase (MAPK), cell cycle and apoptosis signaling pathways, and were involved in cellular growth, cellular proliferation, apoptosis and the humoral immune response. The results of the present study suggest that the 165 differentially expressed proteins, including S100 calcium-binding protein A6 (S100A6) and superoxide dismutase 3 (SOD3) in the microenvironment of gastric mucosal atypical hyperplasia, are involved in the p53, MAPK, cell cycle and apoptosis signaling pathways, and serve a function in the pathogenesis of gastric cancer.

Therapeutic effects of recombinant human S100A6 and soluble receptor for advanced glycation end products(sRAGE) on CCl4-induced liver fibrosis in mice

Hepatic fibrosis is a pathological process in which extracellular matrix excessively aggregates in an injured liver. Research on hepatic fibrosis is expanding, however, much information in this process is still unclear. Here, we examined the gene expression changes within the process of liver fibrosis, providing the first evidence that secreted S100A6 is a critical contributor. We discovered that expression of the S100 family is highly correlated with CCl₄-induced liver fibrosis and post self-recovery in mice. Recombinant human S100A6 (rhS100A6) introduced to CCl₄-induced mice was found to enhance liver fibrosis through the promotion of activated hepatic stellate cell (HSC) proliferation. More importantly, we showed that rhS100A6 can induce cell cycle transition from S to G2 stage and significantly elevate the level of ERK phosphorylation in the MARK pathway. In contrast to rhS100A6, recombinant human and soluble receptor for advanced glycation end products (sRAGE), a natural antagonist of the S100/RAGE pathway, was found to have a preventative effect on liver fibrosis in CCl₄-induced mice. In conclusion, our study supports that S100A6 could be a novel therapeutic in liver fibrosis and its receptor antagonist, sRAGE, proofed to be effective for the treatment of liver fibrosis.

Serum microRNA signatures and metabolomics have high diagnostic value in gastric cancer

BACKGROUND

Many novel diagnostic biomarkers have been developed for gastric cancer (GC) recently. We chose two methods with high diagnostic value, the detection of serum microRNAs and metabolomics based on gas chromatography/mass spectrometry (GC/MS), and aimed to establish appropriate models.

METHODS

We reviewed the diagnostic accuracies of all microRNAs identified by previous diagnostic tests. Then appropriate microRNAs and their combinations were validated the diagnostic value. We included 80 patients with GC and 82 healthy controls (HCs) and detected the expression of the microRNAs. GC/MS analysis was conducted, and we used three multivariate statistical analyses to establish diagnostic models. The concentrations of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were detected for comparison with the novel models.

RESULTS

Sixty-seven published studies and 70 microRNAs were finally included in the systematic review. MiR-18a, miR-19a, miR-21, miR-92a, miR-199a and miR-421 were chosen to further validate their diagnostic efficiencies. Five of those microRNAs in GC patients had significantly different expression. The combination of miR-19a and miR-92a had the highest area under the curve (AUC) at 0.850 with a sensitivity of 91.3% and a specificity of 61.0%. The GC/MS analysis performed an excellent diagnostic value and the AUC reached 1.0.

CONCLUSION

There is a good potential for microRNAs and GC/MS analysis as new diagnostic methods in view of their high diagnostic value compared with traditional biomarkers.

S100A6 promotes proliferation of intrahepatic cholangiocarcinoma cells via the activation of the p38/MAPK pathway

Aim: We explored the expression of S100A6 and its role in intrahepatic cholangiocarcinoma (ICC). Methods: The expression of S100A6 in ICC samples was detected by immunohistochemistry. In vitro experiments, we silenced and overexpressed S100A6 to investigate its role in cell functions. Results: The expression of S100A6 was markedly increased in ICC tissues and cell lines. S100A6 overexpression was an independent risk factor for patients’ survival. Silencing S100A6 resulted in a suppression of proliferation and p38/MAPK activity, while overexpressing S100A6 caused a promotion of proliferation and p38/MAPK. Discussion: S100A6 participated in the proliferation of ICC cells and correlated with a more aggressive behavior of ICC. Conclusion: S100A6 may serve as a novel prognostic marker and a potential therapeutic target for ICC patients.

S100A6 - focus on recent developments

The Ca2+-binding protein, S100A6, belongs to the S100 family. Binding of Ca2+ induces a conformational change, which causes an increase in the overall S100A6 hydrophobicity and allows it to interact with many targets. S100A6 is expressed in different normal tissues and in many tumors. Up to now it has been shown that S100A6 is involved in cell proliferation, cytoskeletal dynamics and tumorigenesis, and that it might have some extracellular functions. In this review, we summarize novel discoveries concerning S100A6 targets, its involvement in cellular signaling pathways, and presence in stem/progenitor cells, extracellular matrix and body fluids of diseased patients.

Calcium-regulatory proteins as modulators of chemotherapy in human neuroblastoma

Neuroblastoma (NB) is a pediatric cancer treated with poly-chemotherapy including platinum complexes (e.g. cisplatin (CDDP), carboplatin), DNA alkylating agents, and topoisomerase I inhibitors (e.g. topotecan (TOPO)). Despite aggressive treatment, NB may become resistant to chemotherapy. We investigated whether CDDP and TOPO treatment of NB cells interacts with the expression and function of proteins involved in regulating calcium signaling. Human neuroblastoma cell lines SH-SY5Y, IMR-32 and NLF were used to investigate the effects of CDDP and TOPO on cell viability, apoptosis, calcium homeostasis, and expression of selected proteins regulating intracellular calcium concentration ([Ca²⁺]_i). In addition, the impact of pharmacological inhibition of [Ca²⁺]_i-regulating proteins on neuroblastoma cell survival was studied. Treatment of neuroblastoma cells with increasing concentrations of CDDP (0.1−10 μM) or TOPO (0.1 nM−1 μM) induced cytotoxicity and increased apoptosis in a concentration- and time-dependent manner. Both drugs increased [Ca²⁺]_i over time. Treatment with CDDP or TOPO also modified mRNA expression of selected genes encoding [Ca²⁺]_i-regulating proteins. Differentially regulated genes included S100A6, ITPR1, ITPR3, RYR1 and RYR3. With FACS and confocal laser scanning microscopy experiments we validated their differential expression at the protein level. Importantly, treatment of neuroblastoma cells with pharmacological modulators of [Ca²⁺]_i-regulating proteins in combination with CDDP or TOPO increased cytotoxicity. Thus, our results confirm an important role of calcium signaling in the response of neuroblastoma cells to chemotherapy and suggest [Ca²⁺]_i modulation as a promising strategy for adjunctive treatment.

S100A6 protein: functional roles

S100A6 protein belongs to the A group of the S100 protein family of Ca2+-binding proteins. It is expressed in a limited number of cell types in adult normal tissues and in several tumor cell types. As an intracellular protein, S100A6 has been implicated in the regulation of several cellular functions, such as proliferation, apoptosis, the cytoskeleton dynamics, and the cellular response to different stress factors. S100A6 can be secreted/released by certain cell types which points to extracellular effects of the protein. RAGE (receptor for advanced glycation endproducts) and integrin β1 transduce some extracellular S100A6's effects. Dosage of serum S100A6 might aid in diagnosis in oncology.

Calcium Sensor, NCS-1, Promotes Tumor Aggressiveness and Predicts Patient Survival

Neuronal Calcium Sensor 1 (NCS-1) is a multi-functional Ca²⁺-binding protein that affects a range of cellular processes beyond those related to neurons. Functional characterization of NCS-1 in neuronal model systems suggests that NCS-1 may influence oncogenic processes. To this end, the biological role of NCS-1 was investigated by altering its endogenous expression in MCF-7 and MB-231 breast cancer cells. Overexpression of NCS-1 resulted in a more aggressive tumor phenotype demonstrated by a marked increase in invasion and motility, and a decrease in cell-matrix adhesion to collagen IV. Overexpression of NCS-1 was also shown to increase the efficacy of paclitaxel-induced cell death in a manner that was independent of cellular proliferation. To determine the association between NCS-1 and clinical outcome, NCS-1 expression was measured in two independent breast cancer cohorts by the Automated Quantitative Analysis method of quantitative immunofluorescence. Elevated levels of NCS-1 were significantly correlated with shorter survival rates. Furthermore, multivariate analysis demonstrated that NCS-1 status was prognostic, independent of estrogen receptor, progesterone receptor, HER2, and lymph node status. These findings indicate that NCS-1 plays a role in the aggressive behavior of a subset of breast cancers and has therapeutic or biomarker potential.Implications: NCS-1, a calcium-binding protein, is associated with clinicopathologic features of aggressiveness in breast cancer cells and worse outcome in two breast cancer patient cohorts. Mol Cancer Res; 15(7); 942-52. ©2017 AACR.

Effects of S100A6 gene silencing on the biological features of eutopic endometrial stromal cells and β‑catenin expression

Protein expression levels of S100 calcium binding protein A6 (S100A6) are increased in various malignancies and are associated with tumor behavior; however, the association between S100A6 and endometriosis remains to be elucidated. In order to investigate the influence of S100A6 protein, recombinant lentivirus siS100A6 was used to transfect the eutopic endometrial stromal cells. CCK-8 assay was performed to identify the proliferation ability of cell and the cell migration was detected by Transwell assay. Flow cytometry was performed to detect cell apoptosis, and western blotting and reverse transcription-quantitative polymerase chain reaction were performed to identify the expression of β-catenin. The present study investigated the role of S100A6 in endometriosis and its interaction with β-catenin by transfecting eutopic endometrial stromal cells with a recombinant lentivirus containing S100A6-specific small interfering RNA. Inhibition of S100A6 expression had a significant antiproliferative effect and reduced the migratory ability of eutopic endometrial stromal cells, and induced their apoptosis. In addition, inhibition of S100A6 expression suppressed β-catenin expression. These results suggested that inhibition of S100A6 may represent a promising novel approach for the targeted therapy of endometriosis.

Integrated Cellular and Plasma Proteomics of Contrasting B-cell Cancers Reveals Common, Unique and Systemic Signatures

Approximately 800,000 leukemia and lymphoma cases are diagnosed worldwide each year. Burkitt's lymphoma (BL) and chronic lymphocytic leukemia (CLL) are examples of contrasting B-cell cancers; BL is a highly aggressive lymphoid tumor, frequently affecting children, whereas CLL typically presents as an indolent, slow-progressing leukemia affecting the elderly. The B-cell-specific overexpression of the myc and TCL1 oncogenes in mice induce spontaneous malignancies modeling BL and CLL, respectively. Quantitative mass spectrometry proteomics and isobaric labeling were employed to examine the biology underpinning contrasting Eμ-myc and Eμ-TCL1 B-cell tumors. Additionally, the plasma proteome was evaluated using subproteome enrichment to interrogate biomarker emergence and the systemic effects of tumor burden. Over 10,000 proteins were identified (q<0.01) of which 8270 cellular and 2095 plasma proteins were quantitatively profiled. A common B-cell tumor signature of 695 overexpressed proteins highlighted ribosome biogenesis, cell-cycle promotion and chromosome segregation. Eμ-myc tumors overexpressed several methylating enzymes and underexpressed many cytoskeletal components. Eμ-TCL1 tumors specifically overexpressed ER stress response proteins and signaling components in addition to both subunits of the interleukin-5 (IL5) receptor. IL5 treatment promoted Eμ-TCL1 tumor proliferation, suggesting an amplification of IL5-induced AKT signaling by TCL1. Tumor plasma contained a substantial tumor lysis signature, most prominent in Eμ-myc plasma, whereas Eμ-TCL1 plasma contained signatures of immune-response, inflammation and microenvironment interactions, with putative biomarkers in early-stage cancer. These findings provide a detailed characterization of contrasting B-cell tumor models, identifying common and specific tumor mechanisms. Integrated plasma proteomics allowed the dissection of a systemic response and a tumor lysis signature present in early- and late-stage cancers, respectively. Overall, this study suggests common B-cell cancer signatures exist and illustrates the potential of the further evaluation of B-cell cancer subtypes by integrative proteomics.

S100A6 promotes cell proliferation in human nasopharyngeal carcinoma via the p38/MAPK signaling pathway

An elevated level of S100A6 is associated with poor outcomes of many tumor types, but, how S100A6 contributes to nasopharyngeal carcinoma (NPC) progression remains unknown. Here, we investigated the expression and prognostic significance of S100A6 in NPC and explored the molecular mechanisms under-lying the role of S100A6 in NPC development. The results showed that S100A6 was markedly up-regulated in NPC tissues and cell lines compared to paired peritumoral normal tissues and a normal nasopharyngeal epithelial cell line, respectively. In tissues from 92 NPC patients, high S100A6 expression was associated with advanced N stage, locoregional failure and disease progression and was predictive of poor locoregional recurrence-free survival (LRRFS, P = 0.001) and progression-free survival (PFS, P = 0.001). Multivariate analysis showed that S100A6 is an independent prognostic factor for LRRFS and PFS. Silencing S100A6 using siRNA or shRNA significantly suppressed NPC cell proliferation, colony formation and p38/mitogen-activated protein kinase (MAPK) activity in vitro and inhibited tumor growth in a xenograft mouse model of NPC. In contrast, overexpressing S100A6 via plasmid transfection resulted in increased NPC cell proliferation and p38/MAPK activation. S100A6-induced proliferation was abolished by a p38 inhibitor. In summary, S100A6 may be a new prognostic marker of NPC and may promote NPC development via the activation of p38/MAPK signaling pathways. These findings suggest S100A6/p38/MAPK signaling as a potential therapeutic target for NPC. © 2016 Wiley Periodicals, Inc.

Serum levels of S100A6 are unaltered in patients with resectable cholangiocarcinoma

Background

Elevated expression levels of S100A6, a calcium-binding low-molecular-weight protein, were demonstrated in various malignancies. Moreover, increased serum levels of S100A6 were suggested as a novel biomarker for various inflammatory and malignant diseases including lung and gastric cancer. However, up to now, serum concentrations of S100A6 have not been analyzed in patients with cholangiocarcinoma (CCA).

Methods

S100A6 mRNA expression levels were analyzed in human and murine CCA tumor samples, using semi-quantitative reverse transcriptase PCR. S100A6 serum concentrations were measured using an enzyme-linked immunosorbent assay in 112 patients with CCA referred to surgery for curative resection and were compared to those of 42 healthy controls. Results were correlated with clinical data.

Results

S100A6 mRNA expression levels were significantly up-regulated in tumor samples of CCA patients and in tumor tissue of a CCA mouse model. In contrast, serum levels of S100A6 were not significantly altered in patients with CCA compared to healthy controls. Whereas no differences became apparent within the different clinical subgroups of CCA, patients with primary sclerosing cholangitis (PSC)-based CCA displayed higher levels of S100A6 compared to the other patients. Nevertheless, patients with higher S100A6 serum concentrations showed a trend towards an impaired prognosis compared to patients with lower levels. Finally, within our cohort of patients both the diagnostic and prognostic potentials of S100A6 were similar to those of the clinically established biomarkers CEA and CA19-9.

Conclusion

Although S100A6 was expressed at significantly higher levels in human and murine CCA tumor samples, S100A6 serum levels were not regulated in patients with CCA and are thus not suitable for diagnosis of CCA. However, CCA-patients with elevated S100A6 displayed a trend toward an impaired prognosis compared to patients with lower S100A6 levels, supporting its further evaluation as a prognostic biomarker in CCA.

Electronic supplementary material

The online version of this article (doi:10.1186/s40169-016-0120-7) contains supplementary material, which is available to authorized users.

Role of S100 Proteins in Colorectal Carcinogenesis

The family of S100 proteins represents 25 relatively small (9-13 kD) calcium binding proteins. These proteins possess a broad spectrum of important intracellular and extracellular functions. Colorectal cancer is the third most common cancer in men (after lung and prostate cancer) and the second most frequent cancer in women (after breast cancer) worldwide. S100 proteins are involved in the colorectal carcinogenesis through different mechanisms: they enable proliferation, invasion, and migration of the tumour cells; furthermore, S100 proteins increase angiogenesis and activate NF-κβ signaling pathway, which plays a key role in the molecular pathogenesis especially of colitis-associated carcinoma. The expression of S100 proteins in the cancerous tissue and serum levels of S100 proteins might be used as a precise diagnostic and prognostic marker in patients with suspected or already diagnosed colorectal neoplasia. Possibly, in the future, S100 proteins will be a therapeutic target for tailored anticancer therapy.

Expression and clinical implication of S100A12 in gastric carcinoma

S100 protein family has been implicated in multiple stages of tumorigenesis and progression in which S100A12 is one of the subtypes. However, the role of S100A12 in gastric carcinoma (GC) has not been elucidated yet. This study was aimed to investigate the expression of S100A12 in GC tissues and evaluate the clinical significance of S100A12 in GC patients. S100A12 protein was detected in 207 GC and 52 paired non-cancerous mucosal tissues by immunohistochemistry, while messenger RNA (mRNA) was investigated by Oncomine database analysis. Moreover, survival analysis was performed and the correlation between S100A12 and ubiquitin-specific protease 10 (USP10) and p53 was determined. As for tumor cells, the expression of S100A12 protein and mRNA in GC was proved to be lower than that in non-cancerous mucosa tissues (p < 0.05). Clinicopathological analysis showed that S100A12 protein was negatively associated with tumor size (p = 0.004), depth of invasion (p = 0.022), tumor node metastasis (TNM) stage (p = 0.018), Lauren classification (p < 0.000), and cell differentiation (p < 0.000). In contrast, a positive correlation was found between S100A12 and USP10 protein (p < 0.000). However, no relationship was detected between S100A12 and p53. Moreover, the survival analysis indicated that S100A12 protein was a favorable factor of prognosis of GC (p < 0.05). Although the expression of S100A12 in the stromal cells was detected higher than that in the tumor cells, no relationship between S100A12 protein in stromal cells and the clinicopathological features described above was found (p > 0.05). Our findings suggested that low expression of S100A12 might be served as a new marker in the tumorigenesis and progression of GC.

Recent advances in the molecular diagnostics of gastric cancer

Gastric cancer (GC) is the third most common cause of cancer-related death in the world, representing a major global health issue. Although the incidence of GC is declining, the outcomes for GC patients remain dismal because of the lack of effective biomarkers to detect early GC and predict both recurrence and chemosensitivity. Current tumor markers for GC, including serum carcinoembryonic antigen and carbohydrate antigen 19-9, are not ideal due to their relatively low sensitivity and specificity. Recent improvements in molecular techniques are better able to identify aberrant expression of GC-related molecules, including oncogenes, tumor suppressor genes, microRNAs and long non-coding RNAs, and DNA methylation, as novel molecular markers, although the molecular pathogenesis of GC is complicated by tumor heterogeneity. Detection of genetic and epigenetic alterations from gastric tissue or blood samples has diagnostic value in the management of GC. There are high expectations for molecular markers that can be used as new screening tools for early detection of GC as well as for patient stratification towards personalized treatment of GC through prediction of prognosis and drug-sensitivity. In this review, the studies of potential molecular biomarkers for GC that have been reported in the publicly available literature between 2012 and 2015 are reviewed and summarized, and certain highlighted papers are examined.

Effect of S100A6 over-expression on β-catenin in endometriosis

AIM

S100A6 is over-expressed in several human tumors, including pancreatic carcinoma, malignant fibrous histiocytoma, breast, colon, and gastric carcinoma, but little is known about the role of S100A6 in endometriosis. The aim of the present study was to investigate the effect of S100A6 over-expression on β-catenin in endometrial stromal cells.

METHODS

Endometrial stromal cells were transfected with an hS100A6-expressing recombinant lentivirus construct. The expression of β-catenin was assessed using western blot and reverse transcription-polymerase chain reaction.

RESULTS

S100A6 over-expression promoted β-catenin expression at the RNA and protein levels, in endometrial stromal cells.

CONCLUSIONS

S100A6 induces expression of β-catenin in endometrial stromal cells.

A multiplexed, targeted mass spectrometry assay of the S100 protein family uncovers the isoform-specific expression in thyroid tumours

Background

Mounting evidence demonstrates a causal role for S100 proteins in tumourigenesis and several S100 isoforms have shown utility as biomarkers of several types of cancer. The S100 family is comprised of 21 small isoforms, many of them implicated in important cellular functions such as proliferation, motility and survival. Furthermore, in vivo experiments have proven the role of S100 proteins in tumour growth and disease progression, while other studies have shown their prognostic value and involvement in resistance to chemotherapy drugs. Taken together, all these aspects highlight S100 proteins as potential therapeutic targets and as a promising panel of cancer biomarkers. In this work, we have developed a mass spectrometry (MS)-based method for the multiplexed and specific analysis of the entire S100 protein family in tumour tissues and have applied it to investigate the expression of S100 isoforms in the context of thyroid cancer, the main endocrine malignancy.

Methods

Selected Reaction Monitoring (SRM)-MS and stable isotope labelling/label-free analysis were employed to investigate the expression of the 21 S100 protein isoforms in thyroid tissue samples. Specimens included 9 normal thyroid tissues and 27 tumour tissues consisting of 9 follicular adenomas (FA), 8 follicular carcinomas (FTC) and 10 papillary carcinomas (PTC).

Results

The multiplexed and targeted mass spectrometry method led to the detection of eleven S100 protein isoforms across all tissues. Label- and label-free analyses showed the same significant differences and results were confirmed by western blot. S100A6, S100A11 and its putative interaction partner annexin A1 showed the highest overexpression in PTC compared to normal thyroid. S100A13 was also elevated in PTC. Reduced S100A4 expression was observed in FA compared to all other tissues. FA and FTC showed reduction of S100A10 and annexin A2 expression.

Conclusions

Targeted mass spectrometry allows the multiplexed and specific analysis of S100 protein isoforms in tumour tissue specimens. It revealed S100A13 as a novel candidate PTC biomarker. Results show that S100A6, S100A11 and Annexin A1 could help discriminate follicular and papillary tumours. The diagnostic and functional significance of S100A4 and S100A10 reduction in follicular tumours requires further investigation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1217-x) contains supplementary material, which is available to authorized users.

S100 calcium-binding protein A6 promotes epithelial-mesenchymal transition through β-catenin in pancreatic cancer cell line

The pathogenesis of pancreatic ductal adenocarcinoma (PDAC) remains poorly understood. S100 calcium-binding protein A6 (S100A6) has been associated with PDAC; however, the effect of S100A6 on PDAC migration and invasion has not yet been explored. In this study, Panc-1 cells were transfected with a plasmid to induce overexpression of S100A6, and β-catenin was knocked down using a specific short hairpin RNA (shRNA). The wound-healing and Transwell assays demonstrated that S100A6 promoted PDAC cell migration and invasion. Furthermore, β-catenin shRNA inhibited the migration and invasion of PDAC cells. We confirmed that S100A6 induces PDAC cell migration and invasion via activation of β-catenin in vitro. Assessment of mRNA and protein levels revealed that S100A6 induces increased expression of β-catenin, N-cadherin and vimentin, and decreased expression of E-cadherin in PDAC cells. β-catenin shRNA also altered the expression of epithelial-mesenchymal transition (EMT)-related markers in PDAC cells. Specifically, expression of E-cadherin was increased, whereas expression of N-cadherin and vimentin was decreased. Finally, we demonstrated that S100A6 alters the expression of EMT-related markers via β-catenin activation. In conclusion, S100A6 induces EMT and promotes cell migration and invasion in a β-catenin-dependent manner. S100A6 may therefore represent a novel potential therapeutic target for the treatment of pancreatic cancer.

S100 proteins in cancer

In humans, the S100 protein family is composed of 21 members that exhibit a high degree of structural similarity, but are not functionally interchangeable. This family of proteins modulates cellular responses by functioning both as intracellular Ca(2+) sensors and as extracellular factors. Dysregulated expression of multiple members of the S100 family is a common feature of human cancers, with each type of cancer showing a unique S100 protein profile or signature. Emerging in vivo evidence indicates that the biology of most S100 proteins is complex and multifactorial, and that these proteins actively contribute to tumorigenic processes such as cell proliferation, metastasis, angiogenesis and immune evasion. Drug discovery efforts have identified leads for inhibiting several S100 family members, and two of the identified inhibitors have progressed to clinical trials in patients with cancer. This Review highlights new findings regarding the role of S100 family members in cancer diagnosis and treatment, the contribution of S100 signalling to tumour biology, and the discovery and development of S100 inhibitors for treating cancer.