Tumor expression of S100A6 correlates with survival of patients with stage I non-small-cell lung cancer

S100A6 could not promote the differentiation of Calu-6 lung cancer cell line

Background

Our previous study demonstrated that S100 calcium binding protein A6 (S100A6) impairs tumorigenesis by Calu-6 lung cancer cells, as well as inhibit their growth. However, the role that S100A6 plays in tumor cell differentiation has not been previously explored. This study aimed to confirm the effect of S100A6 on the direction of differentiation in the human lung cancer cell linem Calu-6m based on our previous published research.

Materials and methods

A S100A6-overexpressing lentiviral vector was successfully constructed in our previous study. Nude mouse tumorigenicity was then applied successfully, and 15 mice were divided into three groups (Calu-6, Calu-6/neo, Calu-6/S100A6). After 5 weeks, we detected lung cancer markers with immunohistochemistry in mice tumor tissues, including the adenocarcinoma markers, TTF-1 and NapsinA, the squamous cell carcinoma markers, P40, CK5/6 and P63, and the small cell lung cancer markers CD56, Syn, CgA, TTF-1, CK, and Ki-67. Differences among the three groups were statistically compared.

Results

All the above-mentioned markers were positive in the tumor tissues of all three groups, and there were no significant differences.

Conclusion

S100A6 cannot promote differentiation of the undifferentiated human lung cancer cell line, Calu-6, into adenocarcinoma, squamous, or small cell carcinoma cell lines.

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.

Liquid Biopsy for Lung Cancer: Up-to-Date and Perspectives for Screening Programs

Lung cancer is the deadliest cancer worldwide. Tissue biopsy is currently employed for the diagnosis and molecular stratification of lung cancer. Liquid biopsy is a minimally invasive approach to determine biomarkers from body fluids, such as blood, urine, sputum, and saliva. Tumor cells release cfDNA, ctDNA, exosomes, miRNAs, circRNAs, CTCs, and DNA methylated fragments, among others, which can be successfully used as biomarkers for diagnosis, prognosis, and prediction of treatment response. Predictive biomarkers are well-established for managing lung cancer, and liquid biopsy options have emerged in the last few years. Currently, detecting EGFR p.(Tyr790Met) mutation in plasma samples from lung cancer patients has been used for predicting response and monitoring tyrosine kinase inhibitors (TKi)-treated patients with lung cancer. In addition, many efforts continue to bring more sensitive technologies to improve the detection of clinically relevant biomarkers for lung cancer. Moreover, liquid biopsy can dramatically decrease the turnaround time for laboratory reports, accelerating the beginning of treatment and improving the overall survival of lung cancer patients. Herein, we summarized all available and emerging approaches of liquid biopsy-techniques, molecules, and sample type-for lung cancer.

The Role of the S100 Protein Family in Glioma

The S100 protein family consists of 25 members and share a common structure defined in part by the Ca²⁺ binding EF-hand motif. Multiple members' dysregulated expression is associated with progression, diagnosis and prognosis in a broad range of diseases, especially in tumors. They could exert wide range of functions both in intracellular and extracellular, including cell proliferation, cell differentiation, cell motility, enzyme activities, immune responses, cytoskeleton dynamics, Ca²⁺ homeostasis and angiogenesis. Gliomas are the most prevalent primary tumors of the brain and spinal cord with multiple subtypes that are diagnosed and classified based on histopathology. Up to now the role of several S100 proteins in gliomas have been explored. S100A8, S100A9 and S100B were highly expression in serum and may present as a marker correlated with survival and prognosis of glioma patients. Individual member was confirmed as a new regulator of glioma stem cells (GSCs) and a mediator of mesenchymal transition in glioblastoma (GBM). Additionally, several members up- or downregulation have been reported to involve in the development of glioma by interacting with signaling pathways and target proteins. Here we detail S100 proteins that are associated with glioma, and discuss their potential effects on progression, diagnosis and prognosis.

Molecular Characteristics of RAGE and Advances in Small-Molecule Inhibitors

Receptor for advanced glycation end-products (RAGE) is a member of the immunoglobulin superfamily. RAGE binds and mediates cellular responses to a range of DAMPs (damage-associated molecular pattern molecules), such as AGEs, HMGB1, and S100/calgranulins, and as an innate immune sensor, can recognize microbial PAMPs (pathogen-associated molecular pattern molecules), including bacterial LPS, bacterial DNA, and viral and parasitic proteins. RAGE and its ligands stimulate the activations of diverse pathways, such as p38MAPK, ERK1/2, Cdc42/Rac, and JNK, and trigger cascades of diverse signaling events that are involved in a wide spectrum of diseases, including diabetes mellitus, inflammatory, vascular and neurodegenerative diseases, atherothrombosis, and cancer. Thus, the targeted inhibition of RAGE or its ligands is considered an important strategy for the treatment of cancer and chronic inflammatory diseases.

S100A6 represses Calu-6 lung cancer cells growth via inhibiting cell proliferation, migration, invasion and enhancing apoptosis

S100 calcium binding protein A6 (S100A6) has been reported to involve in many kinds of cancers through regulating intracellular calcium homeostasis. Previous studies found that S100A6 increased in lung cancer patients' plasma and pleural effusion. This study focused on its function in Calu-6 lung cancer cells. S100A6 gene was transferred into Calu-6 lung cancer cell line by lentivirus vector, the empty vector transfected cells and the blank cells were set as control groups. MTT was evaluating cell proliferation. The transwell assay was reflecting cell migration and cell invasion. The flow cytometric analysis was detecting cell apoptosis and cell cycle of three groups (Calu-6, Calu-6/neo, Calu-6/S100A6). Nude mouse tumorigenicity was then applied to evaluate S100A6's effect on cellular tumorigenicity. Compared with control groups, Calu-6/S100A6 cells showed a weakening trend in the cell behaviours of proliferation, migration and invasiveness, while had an enhancement of cell apoptosis, with all P < .05. The cell cycle of Calu-6/S100A6 cells had a reduction of S phase and an increase of G1 phase (P < .05). In animal study, after 5 weeks of cell injection, the tumour bulk of Calu-6/S100A6 group was smaller than controls, with P < .05. Our results demonstrate S100A6 inhibits the growth of Calu-6 lung cancer cells, as well as impairs Calu-6's ability in tumorigenesis. At cellular level, S100A6 is supposed to act as a tumour suppressor gene in lung cancer.

Analysis of expression differences of immune genes in non-small cell lung cancer based on TCGA and ImmPort data sets and the application of a prognostic model

Background

There has been little investigation carried out into the activity of immune-related genes in the prognosis of non-small cell lung cancer (NSCLC). Our study set out to analyze the correlation between the differential expression of immune genes and NSCLC prognosis by screening the differential expression of immune genes. Based on the immune genes identified, we aimed to construct a prognostic risk model and explore some novel molecules which have predictive potential for therapeutic effect and prognosis in lung cancer.

Methods

Immune gene transcriptome data and clinical data of NSCLC samples were extracted from TCGA database, and transcription factors in the ImmPort dataset were obtained. The data were divided into two groups: normal tissues and tumor tissues. The expression levels of immune genes were compared using the edgeR algorithm, and then differential expression analysis was performed. The survival analysis was carried out by combining differential immune genes with clinical survival time, so that the immune genes influencing the prognosis of NSCLC could be determined. A risk score was calculated based on the expression levels of the immune genes related to the prognosis of NSCLC and their corresponding coefficients to construct a prognostic risk model. This model was used to calculate patient risk scores and perform clinical correlation analysis. The selected molecules were further verified by clinical samples.

Results

By comparing NSCLC tissues with normal tissues, a total of 6,778 differentially expressed genes were found (P<0.05), of which 490 were differential immune-related genes. Survival analysis determined 28 differential immune genes to be associated with prognosis (P<0.05). We calculated the patient risk value based on the immune gene prognosis model. The survival curve was drawn according to the patient risk score and showed that the survival prognosis was significantly different for the high-risk and the low-risk groups (P<0.05). The area under the receiver operating characteristic (ROC) curve (AUC) was 0.723, which represented a relatively high true-positive rate. All of the results proved the reliability of our immune gene risk prognostic model. After drawing the risk curve, S100A16, IGKV4, S100P, ANGPTL4, SEMA4B, and LGR4 were found to be the high-risk immune genes in NSCLC. Clinical correlation analysis of survival-related differential immune genes revealed that in patients with lymph node metastasis, ANGPTL4 was positively correlated with T stage, S100a16 and SEMA4B were upregulated, and VIPR1 was downregulated. Further analysis revealed that VIPR1 was decreased in metastatic lung cancer compared to non-metastatic lung cancer. Furthermore, the real-time PCR detection of the clinical samples showed that S100A16 expression in lung cancer was increased, while VIPR1 expression in lung cancer was downregulated, which was consistent with the results of our bioinformatics analysis.

Conclusions

Based on big data from the TCGA and ImmPort databases, our study analyzed the relationship between differential expression of immune-related genes and clinical data, and constructed a prognostic model based on the immune genes identified. Two novel molecules, S100A16 and VIPR1, were verified to possibly have significant biological function in NSCLC. Our research may provide us with new insight into the immune genes by which the malignant biological behavior of NSCLC is mediated.

A comprehensive pipeline for translational top-down proteomics from a single blood draw

Top-down proteomics (TDP) by mass spectrometry (MS) is a technique by which intact proteins are analyzed. It has become increasingly popDesalting and concentrating GELFrEEular in translational research because of the value of characterizing distinct proteoforms of intact proteins. Compared to bottom-up proteomics (BUP) strategies, which measure digested peptide mixtures, TDP provides highly specific molecular information that avoids the bioinformatic challenge of protein inference. However, the technique has been difficult to implement widely because of inherent limitations of existing sample preparation methods and instrumentation. Recent improvements in proteoform pre-fractionation and the availability of high-resolution benchtop mass spectrometers have made it possible to use high-throughput TDP for the analysis of complex clinical samples. Here, we provide a comprehensive protocol for analysis of a common sample type in translational research: human peripheral blood mononuclear cells (PBMCs). The pipeline comprises multiple workflows that can be treated as modular by the reader and used for various applications. First, sample collection and cell preservation are described for two clinical biorepository storage schemes. Cell lysis and proteoform pre-fractionation by gel-eluted liquid fractionation entrapment electrophoresis are then described. Importantly, instrument setup and liquid chromatography-tandem MS are described for TDP analyses, which rely on high-resolution Fourier-transform MS. Finally, data processing and analysis are described using two different, application-dependent software tools: ProSight Lite for targeted analyses of one or a few proteoforms and TDPortal for high-throughput TDP in discovery mode. For a single sample, the minimum completion time of the entire experiment is 72 h.

Targeted Mass Spectrometry of S100 Proteins

The S100 protein family has attracted great interest in the field of biomarker research, and a growing number of studies reveal dysregulation of many of the 21 S100 protein isoforms in various human diseases. In cancer, S100 protein expression has been associated with tumor growth, progression, and response to treatment. Some S100 proteins are also considered candidate therapeutic targets. From an analytical perspective, multiplexed analysis of the family-wide S100 protein expression is challenging due to their relatively small size and high-sequence identity. Here we describe a mass spectrometry method using selected reaction monitoring which enables the targeted, multiplexed detection and quantitation of the entire S100 protein family in cell lines and tissue samples.

Clinical significance of calcium-binding protein S100A8 and S100A9 expression in non-small cell lung cancer

Background

The purpose of this study was to evaluate the correlation between calcium‐binding protein S100A8 and S100A9 expression in non‐small cell lung cancer (NSCLC) and patients’ clinical features.

Methods

Fifty‐two NSCLC patients who underwent surgery at Zhejiang Hospital from February 2014 to January 2016 were included in this study. Calcium‐binding protein S100A8 and S100A9 expression patterns in cancer and para‐cancer tissues were examined by immunohistochemistry assay. The correlation between calcium‐binding protein S100A8 and S100A9 expression patterns and NSCLC patients’ clinical characteristics, including age, gender, tumor node metastasis stage, and pathology type, were evaluated.

Results

S100A8 and S100A9 were generally expressed on the cytoplasm and nucleus of NSCLC cells, mainly located in the cytoplasm, stained with brown particles, and distributed evenly. The positive expression rates of S100A8 and S100A9 in cancer tissues were 71.2% and 76.9%, respectively, which were significantly higher than in para‐cancer tissues at 11.5% and 19.2%, respectively, with statistical significance (P < 0.05). S100A8 and S100A9 positive expression was associated with tumor differentiation degree (P < 0.05) but were not correlated with age, gender, smoking history, tumor diameter, pathology type, tumor node metastasis stage, or pleural effusion (P_all > 0.05).

Conclusion

S100A8 and S100A9 positive expression in cancer tissues was significantly higher than in para‐cancer tissues and was correlated with tumor differentiation, which may be a potential marker for poor prognosis.

A review of S100 protein family in lung cancer

S100 protein family, representing 25 relatively small calcium binding proteins, has been reported to be involved in multiple stages of tumorigenesis and progression. These proteins are considered having potential value to be adopted as novel biomarkers in the detection and accurate prediction of many kinds of tumors, including lung cancer. As the one having the highest morbidity and mortality among all cancers, lung carcinoma is still occult for detection, especially at early stage. S100 proteins take participation in the lung neoplasia through playing intracellular and/or extracellular functions, therefore getting involved in a variety of biological processes such as differentiation, proliferation, and migration. A few members have also been testified to modulate TGF-β/Smad-3 mediated transcriptional activity of target genes involved in tumor promotion. In addition to that, a number of proteins in this family have already been reported to experience an abnormal trend in lung cancer at cell, serum and tissue levels. Thus, S100 proteins may serve as effective biomarkers for suspected or already diagnosed lung cancer patients. In future, S100 protein family might be applied as therapeutic targets in clinical treatment of lung cancer. In this review, we firstly summed up the biological and clinical evidence connecting S100 proteins and lung cancer, which has not been summarized before.

High Expression of S100A6 Predicts Unfavorable Prognosis of Lung Squamous Cell Cancer

Background

S100 family of proteins is mainly involved in regulation of intracellular calcium homeostasis. Aberrant expression of S100 family members has been reported in many types of cancers. However, as a member of S100 family, the prognostic value of S100A6 for lung squamous cell carcinoma (SCC) has not been well-studied.

Material/Methods

Using immunohistochemistry, we investigated the expression of S100A6 in 177 patients with SCC and further divided the cohort into a high S100A6 expression group and a low S100A6 expression group. The chi-square test was applied to analyze the correlation between S100A6 expression and clinicopathological factors. Univariate analysis using the Kaplan-Meier method was performed to compare the difference in survival rates between the high S100A6 expression group and the low S100A6 expression group; multivariate analysis with Cox regression model was used to identify independent prognostic risk factors.

Results

In our experiment, we demonstrated that the expression of S100A6 was significantly associated with patient age and tumor differentiation. High-expression of S100A6 was shown to be substantially related to the unfavorable prognosis of SCC. Moreover, our results confirmed that S100A6 was an independent risk factor for SCC prognosis, and could predict unfavorable prognosis.

Conclusions

High-expression of S100A6 was identified as an independent unfavorable prognostic factor for SCC, suggesting that targeting S100A6 may result in the development of potential targeted drug for SCC.

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.

Progress in Top-Down Proteomics and the Analysis of Proteoforms

From a molecular perspective, enactors of function in biology are intact proteins that can be variably modified at the genetic, transcriptional, or post-translational level. Over the past 30 years, mass spectrometry (MS) has become a powerful method for the analysis of proteomes. Prevailing bottom-up proteomics operates at the level of the peptide, leading to issues with protein inference, connectivity, and incomplete sequence/modification information. Top-down proteomics (TDP), alternatively, applies MS at the proteoform level to analyze intact proteins with diverse sources of intramolecular complexity preserved during analysis. Fortunately, advances in prefractionation workflows, MS instrumentation, and dissociation methods for whole-protein ions have helped TDP emerge as an accessible and potentially disruptive modality with increasingly translational value. In this review, we discuss technical and conceptual advances in TDP, along with the growing power of proteoform-resolved measurements in clinical and translational research.

Diagnostic significance of S100A2 and S100A6 levels in sera of patients with non-small cell lung cancer

Biochemical markers play a significant role in the diagnosis of lung cancer. Recent studies have demonstrated a link involving S100 Calcium Binding Proteins (S100A2, S100A6) and non-small cell lung cancer (NSCLC), but the expediency of their serum levels in NSCLC has not been established. In this study, we evaluate the potential of serum S100A2 and S100A6 levels as diagnostic markers for NSCLC. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the levels of S100A2 and S100A6 in 141 NSCLC patients and 150 healthy subjects. Serum levels of the two proteins in patients with NSCLC were higher compared to healthy controls (P = 0.0002 for S100A2 and P < 0.0001 for S100A6). Moreover, the levels of S100A2 and S100A6 were higher in the sera of stage I/II NSCLC patients compared to healthy controls with P = 0.01 and <0.0001, respectively. Receiver operating characteristic (ROC) analysis showed that S100A2 could distinguish NSCLC patients from healthy controls (AUC = 0.646), and S100A6 could also identify NSCLC (AUC = 0.668). Meanwhile, these two proteins showed notable capabilities for distinguishing stage I/II NSCLC from healthy controls (AUC = 0.708 for S100A2 and AUC = 0.702 for S100A6). Our results indicate that serum levels of S100A2 and S100A6 are significantly elevated in early stage NSCLC and may have the potential for NSCLC biomarker. Further studies with large sample population would help validate our findings.

Annexin A2 complexes with S100 proteins: structure, function and pharmacological manipulation

Annexin A2 (AnxA2) was originally identified as a substrate of the pp60v-src oncoprotein in transformed chicken embryonic fibroblasts. It is an abundant protein that associates with biological membranes as well as the actin cytoskeleton, and has been implicated in intracellular vesicle fusion, the organization of membrane domains, lipid rafts and membrane-cytoskeleton contacts. In addition to an intracellular role, AnxA2 has been reported to participate in processes localized to the cell surface including extracellular protease regulation and cell-cell interactions. There are many reports showing that AnxA2 is differentially expressed between normal and malignant tissue and potentially involved in tumour progression. An important aspect of AnxA2 function relates to its interaction with small Ca²⁺-dependent adaptor proteins called S100 proteins, which is the topic of this review. The interaction between AnxA2 and S100A10 has been very well characterized historically; more recently, other S100 proteins have been shown to interact with AnxA2 as well. The biochemical evidence for the occurrence of these protein interactions will be discussed, as well as their function. Recent studies aiming to generate inhibitors of S100 protein interactions will be described and the potential of these inhibitors to further our understanding of AnxA2 S100 protein interactions will be discussed.

Systems biology approaches to develop innovative strategies for lung cancer therapy

Lung cancer (LC) is a number one killer of cancer-related death among men and women worldwide. Major advances have been made in the diagnosis, staging and use of surgery for LC, but systemic chemotherapy and radiotherapy alone or in combination with some targeted agents remains the core treatment of advanced LC. Unfortunately, in spite of improved diagnosis, surgical methods and new treatments, mortality is still extremely high among LC patients. To understand the precise functioning of signaling pathways associated with resistance to current treatments in LC, as well as to identify novel treatment regimens, a holistic approach to analyze signaling networks should be applied. Here, we describe systems biology-based approaches to generate biomarkers and novel therapeutic targets in LC, as well as how this may contribute to personalized treatment for this malignancy.

Vascular endothelial growth factor receptor 2, but not S100A4 or S100A6, correlates with prolonged survival in advanced urothelial carcinoma

OBJECTIVE

A major challenge in muscle-invasive urothelial carcinoma (UC) is to identify biomarkers that can predict disease prognosis and treatment response after cystectomy. Therefore, we analyzed the potential prognostic value of the proteins vascular endothelial growth factor receptor 2 (VEGFR2), S100A4, and S100A6 in UC.

METHODS

Retrospective outcome data and tumor specimens from 83 cystectomy patients with histologically confirmed invasive UC were included. Expression levels of VEGFR2 (also called flk-1 and KDR), S100A4, and S100A6 were analyzed in primary tumor tissue by immunohistochemistry.

RESULTS

Immunohistochemical staining and analysis of VEGFR2, S100A4, and S100A6 showed localization mainly in tumor cell cytoplasm. High VEGFR2 expression and low tumor category were independent variables associated with longer overall survival (OS) and disease-free survival, revealed by a bivariate Cox proportional hazards regression model (both P<0.001). In addition, the univariate log-rank test and the Cox model demonstrated that OS beyond 2 years was significantly greater among patients with low S100A6 expression than in those with high S100A6 expression (P = 0.017 and 0.022, respectively). Differences in tumor expression of S100A4 were not significantly associated with outcome.

CONCLUSION

In this study, VEGFR2 expression was significantly correlated with risk of disease relapse and OS in a defined cohort of patients with UC of the bladder treated by cystectomy.

Changes in protein expression in rat bronchoalveolar lavage fluid after exposure to zinc oxide nanoparticles: an iTRAQ proteomic approach

RATIONALE

Zinc oxide nanoparticles (ZnO NPs) are widely used in consumer products and various biomedical fields. As a result, humans are frequently exposed to these NPs. However, there is a lack of information about the proteins that are expressed in the airway in response to exposure to ZnO NPs.

METHODS

Bronchoalveolar lavage fluid (BALF) from Sprague-Dawley (SD) rats that had been exposed to high-dose 35 nm ZnO NPs (N = 6) and filtered air (N = 4) was collected and then labeled with isobaric tags for relative and absolute quantitation (iTRAQ). The differentially expressed proteins were identified by two-dimensional liquid chromatography/tandem mass spectrometry (2D-LC/MS/MS) and further classified by Gene Ontology (GO) annotation.

RESULTS

A total of 46 proteins displayed significant changes after exposure. GO annotation of these differentially expressed proteins indicated that exposure to ZnO NPs mainly affected immune and inflammatory processes. Furthermore, S100A8 and S100A9, candidate markers of idiopathic pulmonary fibrosis and lung cancer, were significantly up-regulated (2.78- and 2.87-fold, respectively) following exposure.

CONCLUSIONS

Our data are consistent with recent study results that exposure to ZnO NPs induces lung inflammation. These data contribute to a better understanding of how exposure to ZnO NPs leads to lung damage through the functional classification of these proteins.

Increased expression of S100A6 promotes cell proliferation and migration in human hepatocellular carcinoma

High levels of S100A6 have been associated with poor outcome in some types of human cancers, but the role of S100A6 in the molecular pathogenesis of these cancers is largely unknown. This study was performed to explore the expression and functional roles of S100A6 in hepatocellular carcinoma (HCC). The expression level of S100A6 in HCC tumor and corresponding peritumoral tissues were determined by immunohistochemistry analysis. The potential functions of S100A6 in tumorigenesis and metastasis were analyzed by cell proliferation, migration, and invasion assays in human liver cancer cells. Moreover, through expression and purification of S100A6 recombinant protein tagged with cell-penetrating peptide, we analyzed its complex extracellular/intracellular effects in a S100A6-silenced cellular model. As a result, the expression of S100A6 was up-regulated in human HCC compared with adjacent peritumoral tissues. S100A6 silencing inhibited the growth and motility of HCC cells, while intracellular re-expression of S100A6 could rescue the proliferation and migration defects. Intracellular over-expression of S100A6 resulted in down-regulation of E-cadherin expression and promoted nuclear accumulation of β-catenin. Moreover, we found that the enhanced cell proliferation and motility after S100A6 stimulation were dependent on the activation of PI3K/AKT pathway. These results suggest that S100A6 may be involved in promotion and progression of human liver cancer.

KEY MESSAGES

S100A6 is overexpressed in human hepatocellular carcinoma clinical specimens. S100A6 promotes proliferation and migration of human hepatoma cells. Overexpression of S100A6 results in alteration of E-cadherin and β-catenin. The multi-effects of S100A6 may be mediated in part by PI3K/AKT pathway activation.

Osteopontin is a prognostic biomarker in non-small cell lung cancer

BACKGROUND

In a previously published report we characterized the expression of the metastasis-associated proteins S100A4, osteopontin (OPN) and ephrin-A1 in a prospectively collected panel of non-small cell lung cancer (NSCLC) tumors. The aim of the present follow-up study was to investigate the prognostic impact of these potential biomarkers in the same patient cohort. In addition, circulating serum levels of OPN were measured and single nucleotide polymorphisms (SNP) in the -443 position of the OPN promoter were analyzed.

METHODS

Associations between immunohistochemical expression of S100A4, OPN and ephrin-A1 and relapse free and overall survival were examined using univariate and multivariate analyses. Serum OPN was measured by ELISA, polymorphisms in the -443 position of the tumor OPN promoter were analyzed by PCR, and associations between OPN levels and promoter polymorphisms and clinicopathological parameters and patient outcome were investigated.

RESULTS

High expression of OPN in NSCLC tumors was associated with poor patient outcome, and OPN was a strong, independent prognostic factor for both relapse free and overall survival. Serum OPN levels increased according to tumor pT classification and tumor size, and patients with OPN-expressing tumors had higher serum levels than patients with OPN-negative tumors. S100A4 was a negative prognostic factor in several subgroups of adenocarcinoma patients, but not in the overall patient cohort. There was no association between ephrin-A1 expression and patient outcome.

CONCLUSIONS

OPN is a promising prognostic biomarker in NSCLC, and should be further explored in the selection of patients for adjuvant treatment following surgical resection.

Quantitative proteomics profiling of primary lung adenocarcinoma tumors reveals functional perturbations in tumor metabolism

In this study, we have analyzed human primary lung adenocarcinoma tumors using global mass spectrometry to elucidate the biological mechanisms behind relapse post surgery. In total, we identified over 3000 proteins with high confidence. Supervised multivariate analysis was used to select 132 proteins separating the prognostic groups. Based on in-depth bioinformatics analysis, we hypothesized that the tumors with poor prognosis had a higher glycolytic activity and HIF activation. By measuring the bioenergetic cellular index of the tumors, we could detect a higher dependency of glycolysis among the tumors with poor prognosis. Further, we could also detect an up-regulation of HIF1α mRNA expression in tumors with early relapse. Finally, we selected three proteins that were upregulated in the poor prognosis group (cathepsin D, ENO1, and VDAC1) to confirm that the proteins indeed originated from the tumor and not from a stromal or inflammatory component. Overall, these findings show how in-depth analysis of clinical material can lead to an increased understanding of the molecular mechanisms behind tumor progression.

Clinical significance of E-cadherin, β-catenin, vimentin and S100A4 expression in completely resected squamous cell lung carcinoma

OBJECTIVE

The aim of this study was to evaluate the prognostic value of E-cadherin, β-catenin, vimentin and S100A4 expression in a cohort of squamous cell lung carcinoma (SqCC) patients.

METHODS

Tumours from 204 patients with surgically resected SqCC were used for the immunohistochemical analyses of E-cadherin, β-catenin, vimentin and S100A4 expression. Correlations between the expression of these markers and clinicopathological parameters were analysed using the χ(2) test. The prognostic value of these markers was evaluated using univariate Kaplan-Meier survival analyses and multivariate Cox proportional hazards model analyses.

RESULTS

Significant associations between E-cadherin expression and T stage (p=0.040), histological differentiation (p=0.005), lymph node metastasis (p<0.001), and recurrence (p<0.001) were identified. Decreased β-catenin expression was significantly correlated with T stage (p=0.003) and lymph node metastasis (p=0.010). Vimentin expression was associated with histological differentiation (p=0.017) and lymph node metastasis (p=0.001). Moreover, significant correlations were observed between S100A4 expression and lymph node metastasis (p=0.020) and recurrence (p<0.001). In the univariate analyses, high E-cadherin expression was a positive indicator for overall survival (OS) (p<0.001) and disease-free survival (DFS) (p<0.001), whereas high S100A4 or vimentin expression were negative indicators for OS (p<0.001 and p=0.010, respectively) and DFS (p<0.001 and p=0.006, respectively). In the multivariate analyses, E-cadherin and S100A4 expression were independent prognostic factors for OS (HR 0.697, 95% CI 0.524 to 0.926, p=0.013, and HR 1.508, 95% CI 1.122 to 2.027, p=0.007, respectively) and DFS (HR 0.634, 95% CI 0.471 to 0.852, p=0.003, and HR 1.490, 95% CI 1.101 to 2.015, p=0.010, respectively).

CONCLUSIONS

Effective analysis of E-cadherin and S100A4 expression may allow for the identification of patients who are at a high risk of recurrence and poor prognosis in SqCC.

S100A4 interacts with p53 in the nucleus and promotes p53 degradation

S100A4 is a small calcium-binding protein that is commonly overexpressed in a range of different tumor types, and it is widely accepted that S100A4 has an important role in the process of cancer metastasis. In vitro binding assays has shown that S100A4 interacts with the tumor suppressor protein p53, indicating that S100A4 may have additional roles in tumor development. In the present study, we show that endogenous S100A4 and p53 interact in complex samples, and that the interaction increases after inhibition of MDM2-dependent p53 degradation using Nutlin-3A. Further, using proximity ligation assay, we show that the interaction takes place in the cell nucleus. S100A4 knockdown experiments in two p53 wild-type cell lines, A549 and HeLa, resulted in stabilization of p53 protein, indicating that S100A4 is promoting p53 degradation. Finally, we demonstrate that S100A4 knockdown leads to p53-dependent cell cycle arrest and increased cisplatin-induced apoptosis. Thus, our data add a new layer to the oncogenic properties of S100A4 through its inhibition of p53-dependent processes.

Mass spectrometry-based proteomics: the road to lung cancer biomarker discovery

Lung cancer is the leading cause of cancer death in men and women in Western nations, and is among the deadliest cancers with a 5-year survival rate of 15%. The high mortality caused by lung cancer is attributable to a late-stage diagnosis and the lack of effective treatments. So, it is crucial to identify new biomarkers that could function not only to detect lung cancer at an early stage but also to shed light on the molecular mechanisms that underlie cancer development and serve as the basis for the development of novel therapeutic strategies. Considering that DNA-based biomarkers for lung cancer showed inadequate sensitivity, specificity, and reproducibility, proteomics could represent a better tool for the identification of useful biomarkers and therapeutic targets for this cancer type. Among the proteomics technologies, the most powerful tool is mass spectrometry. In this review, we describe studies that use mass spectrometry-based proteomics technologies to analyze tumor proteins and peptides, which might represent new diagnostic, prognostic, and predictive markers for lung cancer. We focus in particular on those findings that hold promise to impact significantly on the clinical management of this disease.

Efficacy of aerosolized celecoxib encapsulated nanostructured lipid carrier in non-small cell lung cancer in combination with docetaxel

PURPOSE

Evaluation of in-vivo anticancer activity of aerosolized Celecoxib encapsulated Nanolipidcarriers (Cxb-NLC) as a single therapeutic agent and combined with intravenously administered Docetaxel (Doc) against non-small cell lung cancer.

METHODS

Cxb-NLC were prepared by high-pressure homogenization and were characterized for its physicochemical characteristics. Metastatic A549 tumor model in Nu/Nu mice was used to evaluate response of aerosolized Cxb-NLC & Doc. Isolated lung tumor samples were analyzed for: a) DNA fragmentation and cleaved caspase-3 by immunohistochemistry, b) apoptotic and angiogenic protein markers by western blot, c) global proteomic alterations by an isobaric labeling quantitative proteomic method and d) toxicity studies of NLC.

RESULTS

The particle size of Cxb-NLC was 217 ± 20 nm, while entrapment efficiency was more than 90%. Cxb-NLC and Doc alone and in combination showed 25 ± 4%, 37 ± 5%, and 67 ± 4% reduction in tumor size respectively compared to control. Proteomic analysis with combination treatment further revealed significantly decreased expression of multiple pro-survival and pro-metastasis proteins as well as tumor invasion markers and the expression of S100 family proteins, such as S100A6 and S100P were decreased by 2.5 and 1.6 fold.

CONCLUSIONS

Combination therapy with Cxb-NLC and Doc showed significant reduction in tumor growth which was further confirmed by proteomic analysis.

The S100A6 calcium-binding protein regulates endothelial cell-cycle progression and senescence

Endothelial cells regulate many aspects of vascular physiology, including vasculogenesis and angiogenesis. The S100 family of calcium-binding proteins regulates many aspects of cell function but their roles in vascular physiology are less well understood. Herein, we investigated the expression and function of S100-related family members in endothelial cells. Analysis of total endothelial mRNAs using a human gene chip array revealed significant gene expression of the S100 calcium-binding protein family members S100A6, S100A10, S100A11 and S100A13. We then examined the expression and functional properties of the major S100 family member, S100A6, in vascular endothelial cells. Comparison of primary and transformed human cells revealed significant differences in S100A6 protein levels in these cells. In primary human endothelial cells, S100A6 was present in both the nucleus and the cytoplasm. To assess the function of endothelial S100A6, we depleted protein levels using RNA interference and this caused increased cell-cycle arrest in the G2/M phase under different conditions. S100A6 depletion caused a decrease in both cyclin-dependent kinase 1 (CDK1) and phospho-CDK1 levels, which are essential for eukaryote cell-cycle progression. S100A6 depletion also decreased expression of CDK1, cyclin A1 (CCNA1) and cyclin B (CCNB1) genes with effects on cell-cycle progression. Depletion of endothelial S100A6 levels also elevated β-galactosidase expression, which is an important hallmark of cellular senescence and exit from the mammalian cell cycle. We thus propose that S100A6 has an important role in regulating endothelial commitment to, and progression through, the cell cycle.

Expression of S100A4, ephrin-A1 and osteopontin in non-small cell lung cancer

Background

The metastasis-promoting protein S100A4 induces expression of ephrin-A1 and osteopontin in osteosarcoma cell lines. The aim of this study was to investigate S100A4-mediated stimulation of ephrin-A1 and osteopontin in non-small cell lung cancer (NSCLC) cell lines, and to characterize the expression of these biomarkers in primary tumor tissue from NSCLC patients.

Methods

Four NSCLC cell lines were treated with extracellular S100A4, and ephrin-A1 and osteopontin expression was analyzed by real time RT-PCR and Western blotting. Immunohistochemical staining for S100A4, ephrin-A1 and osteopontin was performed on tissue microarrays containing primary tumor samples from a cohort of 217 prospectively recruited NSCLC patients, and associations with clinicopathological parameters were investigated.

Results

S100A4 induced ephrin-A1 mRNA and protein expression in adenocarcinoma, but not in squamous carcinoma cell lines, whereas the level of osteopontin was unaffected by S100A4 treatment. In primary tumors, moderate or strong immunoreactivity was observed in 57% of cases for cytoplasmic S100A4, 46% for nuclear S100A4, 86% for ephrin-A1 and 77% for osteopontin. Interestingly, S100A4 expression was associated with ephrin-A1 also in vivo, but there was no association between S100A4 and osteopontin. Expression levels of S100A4 and ephrin-A1 were significantly higher in adenocarcinomas compared to other histological subtypes, and S100A4-positive tumors were smaller and more differentiated than tumors without expression.

Conclusions

Our findings suggest that S100A4, ephrin-A1 and osteopontin are involved in the biology of NSCLC, and further investigation of their potential use as biomarkers in NSCLC is warranted.

Changes in the proteomic profile of adipose tissue-derived mesenchymal stem cells during passages

BACKGROUND

Human mesenchymal stem cells (hMSC) have recently raised the attention because of their therapeutic potential in the novel context of regenerative medicine. However, the safety of these new and promising cellular products should be carefully defined before they can be used in the clinical setting, as. The protein expression profile of these cells might reveal potential hazards associated with senescence and tumoral transformation which may occur during culture. Proteomic is a valuable tool for hMSC characterization and identification of possible changes during expansion.

RESULTS

We used Surface Enhanced Laser Desorption/Ionization-Time Of Flight-Mass Spectrometry (SELDI-ToF-MS) to evaluate the presence of stable molecular markers in adipose tissue-derived mesenchymal stem cells (AD-MSC) produced under conditions of good manufacturing practices (GMP). Proteomic patterns of cells prepared were consistent, with 4 up-regulated peaks (mass-to-charge ratio (m/z) 8950, 10087, 10345, and 13058) through subculture steps (P0-P7) with similar trend in three donors. Among the differentially expressed proteins found in the cytoplasmic and nuclear fractions, a cytoplasmic 10.1 kDa protein was upregulated during culture passages and was identified as S100A6 (Calcyclin).

CONCLUSIONS

This study suggests for the first time that common variation could occur in AD-MSC from different donors, with the identification of S100A6, a protein prevalently related to cell proliferation and cell culture condition. These results support the hypothesis of common proteomic changes during MSCs expansion and could give important insight in the knowledge of molecular mechanisms intervening during MSC expansion.

Matrix-assisted laser desorption/ionization mass spectrometry reveals decreased calcylcin expression in small cell lung cancer

To date, most of the proteomic analyses on lung cancer tissue samples have been performed using surgical specimens, which are obtained after a diagnosis is made. To determine if a proteomic signature obtained from bronchoscopic biopsy samples could be found to assist with diagnosis, 50 lung cancer bronchoscopic biopsy samples and 13 adjacent normal lung tissue samples were analyzed using histology-directed, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Lung tissue samples were cryosectioned, and sinapinic acid was robotically deposited on areas of each tissue section enriched in epithelial cells, either tumor or normal. Mass spectra were acquired using a MALDI-time of flight instrument. Small cell lung cancers (SCLCs) demonstrated clearly different protein profiles from normal lung tissue and from non-small cell lung cancers (NSCLCs). Calcyclin (m/z= 10,094.7) was identified to be underexpressed in small cell lung cancers, as compared with non-small cell lung cancers and normal lung tissue. An immunohistochemistry study using 152 NSCLCs and 21 SCLCs confirmed significantly reduced calcyclin stain in SCLCs. Thus, protein profiles obtained from bronchoscopic biopsy samples via MALDI MS distinguish cancerous epithelium from normal lung tissue and between NSCLCs and SCLCs.

A robust tool for discriminative analysis and feature selection in paired samples impacts the identification of the genes essential for reprogramming lung tissue to adenocarcinoma

BACKGROUND

Lung cancer is the leading cause of cancer deaths in the world. The most common type of lung cancer is lung adenocarcinoma (AC). The genetic mechanisms of the early stages and lung AC progression steps are poorly understood. There is currently no clinically applicable gene test for the early diagnosis and AC aggressiveness. Among the major reasons for the lack of reliable diagnostic biomarkers are the extraordinary heterogeneity of the cancer cells, complex and poorly understudied interactions of the AC cells with adjacent tissue and immune system, gene variation across patient cohorts, measurement variability, small sample sizes and sub-optimal analytical methods. We suggest that gene expression profiling of the primary tumours and adjacent tissues (PT-AT) handled with a rational statistical and bioinformatics strategy of biomarker prediction and validation could provide significant progress in the identification of clinical biomarkers of AC. To minimise sample-to-sample variability, repeated multivariate measurements in the same object (organ or tissue, e.g. PT-AT in lung) across patients should be designed, but prediction and validation on the genome scale with small sample size is a great methodical challenge.

RESULTS

To analyse PT-AT relationships efficiently in the statistical modelling, we propose an Extreme Class Discrimination (ECD) feature selection method that identifies a sub-set of the most discriminative variables (e.g. expressed genes). Our method consists of a paired Cross-normalization (CN) step followed by a modified sign Wilcoxon test with multivariate adjustment carried out for each variable. Using an Affymetrix U133A microarray paired dataset of 27 AC patients, we reviewed the global reprogramming of the transcriptome in human lung AC tissue versus normal lung tissue, which is associated with about 2,300 genes discriminating the tissues with 100% accuracy. Cluster analysis applied to these genes resulted in four distinct gene groups which we classified as associated with (i) up-regulated genes in the mitotic cell cycle lung AC, (ii) silenced/suppressed gene specific for normal lung tissue, (iii) cell communication and cell motility and (iv) the immune system features. The genes related to mutagenesis, specific lung cancers, early stage of AC development, tumour aggressiveness and metabolic pathway alterations and adaptations of cancer cells are strongly enriched in the AC PT-AT discriminative gene set. Two AC diagnostic biomarkers SPP1 and CENPA were successfully validated on RT-RCR tissue array. ECD method was systematically compared to several alternative methods and proved to be of better performance and as well as it was validated by comparison of the predicted gene set with literature meta-signature.

CONCLUSIONS

We developed a method that identifies and selects highly discriminative variables from high dimensional data spaces of potential biomarkers based on a statistical analysis of paired samples when the number of samples is small. This method provides superior selection in comparison to conventional methods and can be widely used in different applications. Our method revealed at least 23 hundreds patho-biologically essential genes associated with the global transcriptional reprogramming of human lung epithelium cells and lung AC aggressiveness. This gene set includes many previously published AC biomarkers reflecting inherent disease complexity and specifies the mechanisms of carcinogenesis in the lung AC. SPP1, CENPA and many other PT-AT discriminative genes could be considered as the prospective diagnostic and prognostic biomarkers of lung AC.

Lung cancer proteomics: recent advances in biomarker discovery

Lung cancer is the most common cause of cancer death in both men and women in Western countries, with a 5-year survival rate of 15%, which is among the lowest of all cancers. The high mortality from lung cancer is due not only to the late stage diagnosis but also to the lack of effective treatments even for patients diagnosed with stage I lung cancer. Therefore, there is an urgent need to identify new markers for early diagnosis and prognosis that could serve to open novel therapeutic avenues. Proteomics can represent an important tool for the identification of biomarkers and therapeutic targets for lung cancer since DNA-based biomarkers did not prove to have adequate sensitivity, specificity, and reproducibility. In this paper we will describe studies focused on the identification of new diagnostic, prognostic, and predictive markers for lung cancer, using proteomics technologies.

Prognostic impact of S100A9 overexpression in non-small cell lung cancer

S100 proteins have been implicated in the progression and metastasis of several cancers. Among the S100 family, S100A9 is reportedly expressed in non-small cell lung cancer (NSCLC), though the clinical significance and prognostic value of S100A9 expression in NSCLC remains unclear. The aim of the present study was to examine the relationship between S100A9 expression and prognosis in NSCLC patients. S100A9 expression was evaluated by immunohistochemical staining. Seventy patients with NSCLC who had undergone lung resection were enrolled in the study. Overexpression of S100A9 was observed in 38 (54.3%) patients. Kaplan-Meier analysis showed that, following surgery, patients overexpressing S100A9 had a significantly lower 5-year overall survival rate than patients with weak or no expression of S100A9 (P=0.005). This finding was also observed in pathological stage IA patients (P=0.03). Multivariate Cox regression analysis revealed overexpression of S100A9 to be an independent factor predictive of poor disease outcome (hazard ratio, 0.3; 95% confidence interval, 0.1-0.8; P=0.02). Our results suggest that overexpression of S100A9 is associated with a poor prognosis among NSCLC patients and could serve as a marker identifying patients who are at high risk, even at an early pathological stage.

Identification of novel molecular targets for endometrial cancer using a drill-down LC-MS/MS approach with iTRAQ

Background

The number of patients with endometrial carcinoma (EmCa) with advanced stage or high histological grade is increasing and prognosis has not improved for over the last decade. There is an urgent need for the discovery of novel molecular targets for diagnosis, prognosis and treatment of EmCa, which will have the potential to improve the clinical strategy and outcome of this disease.

Methodology and Results

We used a “drill-down” proteomics approach to facilitate the identification of novel molecular targets for diagnosis, prognosis and/or therapeutic intervention for EmCa. Based on peptide ions identified and their retention times in the first LC-MS/MS analysis, an exclusion list was generated for subsequent iterations. A total of 1529 proteins have been identified below the Proteinpilot® 5% error threshold from the seven sets of iTRAQ experiments performed. On average, the second iteration added 78% new peptides to those identified after the first run, while the third iteration added 36% additional peptides. Of the 1529 proteins identified, only 40 satisfied our criteria for significant differential expression in EmCa in comparison to normal proliferative tissues. These proteins included metabolic enzymes (pyruvate kinase M2 and lactate dehydrogenase A); calcium binding proteins (S100A6, calcyphosine and calumenin), and proteins involved in regulating inflammation, proliferation and invasion (annexin A1, interleukin enhancer-binding factor 3, alpha-1-antitrypsin, macrophage capping protein and cathepsin B). Network analyses revealed regulation of these molecular targets by c-myc, Her2/neu and TNF alpha, suggesting intervention with these pathways may be a promising strategy for the development of novel molecular targeted therapies for EmCa.

Conclusions

Our analyses revealed the significance of drill-down proteomics approach in combination with iTRAQ to overcome some of the limitations of current proteomics strategies. This study led to the identification of a number of novel molecular targets having therapeutic potential for targeted molecular therapies for endometrial carcinoma.

Proteomic study of thyroid tumors reveals frequent up-regulation of the Ca2+ -binding protein S100A6 in papillary thyroid carcinoma

BACKGROUND

The accurate diagnosis of thyroid tumors is challenging. Proteomics has emerged as a promising approach for the discovery of molecular diagnostic markers as a potential complement to routine diagnostics.

METHODS

Protein fractions from 29 frozen thyroid tumor tissue samples (10 papillary carcinomas, 9 follicular carcinomas, and 10 follicular adenomas) as well as from normal thyroid tissue were analyzed by surface enhanced laser desorption/ionization time-of-flight mass spectrometry followed by validation by Western blotting and immunohistochemistry.

RESULTS

A Ca2+ binding protein belonging to the S100 family, S100A6, was differentially expressed between papillary and follicular thyroid tumors. Moreover, two posttranslationally modified forms of S100A6 were observed and verified by liquid chromatography-coupled tandem mass spectrometry. Validation by Western blotting displayed a significantly higher expression of S100A6 in papillary thyroid carcinoma (PTC) in comparison with the other tumor groups or normal tissue (p < 0.05). Immunohistochemical analysis on 98 tumors showed that PTC cases had a significantly stronger cytosolic staining and a larger proportion of stained nuclei than follicular tumors. BRAF gene mutation was not significantly associated with S100A6 protein levels.

CONCLUSION

This study supports a role of S100A6 in thyroid tumorigenesis and as a potential aid in the discrimination between follicular thyroid tumors and PTC.

S100A6 overexpression is associated with poor prognosis and is epigenetically up-regulated in gastric cancer

S100A6 has been implicated in a variety of biological functions as well as tumorigenesis. In this study, we investigated the expression status of S100A6 in relation to the clinicopathological features and prognosis of patients with gastric cancer and further explored a possible association of its expression with epigenetic regulation. S100A6 expression was remarkably increased in 67.5% of gastric cancer tissues as compared with matched noncancerous tissues. Statistical analysis demonstrated a clear correlation between high S100A6 expression and various clinicopathological features, such as depth of wall invasion, positive lymph node involvement, liver metastasis, vascular invasion, and tumor-node metastasis stage (P < 0.05 in all cases), as well as revealed that S100A6 is an independent prognostic predictor (P = 0.026) significantly related to poor prognosis (P = 0.0004). Further exploration found an inverse relationship between S100A6 expression and the methylation status of the seventh and eighth CpG sites in the promoter/first exon and the second to fifth sites in the second exon/second intron. In addition, the level of histone H3 acetylation was found to be significantly higher in S100A6-expressing cancer cells. After 5-azacytidine or trichostatin A treatment, S100A6 expression was clearly increased in S100A6 low-expressing cells. In conclusion, our results suggested that S100A6 plays an important role in the progression of gastric cancer, affecting patient prognosis, and is up-regulated by epigenetic regulation.

Lung cancer proteomics, clinical and technological considerations. J Proteomics. 2010;73:1851-1863. [PMID: 20685322 DOI: 10.1016/j.jprot.2010.05.015]

The overall survival of lung cancer patients is disappointingly low. This is due to several factors, including the lack of an effective screening strategy to detect tumors at a potentially curable early stage, a marked resistance of lung cancer cells to drug treatment and a still superficial knowledge about the multifactorial cellular networks that are activated or suppressed during cancer progression. Furthermore, the armamentarium of clinicians and researchers in the field does not yet include reliable biomarkers to predict tumor response to treatment and foresee the natural history of the disease. In the present situation, a potential breakthrough is presented by proteomics technologies with the potential to discover relevant biomarkers which can be accurately quantified in multiplexed assays. Proteomics field can also contribute greatly in the understanding of mechanisms in tumor progression and treatment response. In this review we will describe the work that is being done in the field of lung cancer proteomics, focusing on clinically relevant questions that need to be addressed and on the possible applications of novel technologies.

S100A6 binding protein and Siah-1 interacting protein (CacyBP/SIP): spotlight on properties and cellular function

The CacyBP/SIP protein (S100A6 binding protein and Siah-1 interacting protein) was originally discovered in Ehrlich ascites tumor cells as a S100A6 (calcyclin) target (Filipek and Wojda in Biochem J 320:585-587, 1996; Filipek and Kuźnicki in J Neurochem 70(5):1793-1798, 1998) and later on as a Siah-1 interacting protein (Matsuzawa and Reed in Mol Cell 7(5):915-926, 2001). CacyBP/SIP binds several target proteins such as some calcium binding proteins of the S100 family (Filipek et al. in J Biol Chem 277(32):28848-28852, 2002), Skp1 (Matsuzawa and Reed in Mol Cell 7(5):915-926, 2001), tubulin (Schneider et al. in Biochim Biophys Acta 1773(11):1628-1636, 2007) and ERK1/2 (Kilanczyk et al. in Biochem Biophys Res Commun 380:54-59, 2009). Studies concerning distribution of CacyBP/SIP show that it is present in various tissues and that a particularly high level of CacyBP/SIP is observed in brain (Jastrzebska et al. in J Histochem Cytochem 48(9):1195-1202, 2000). Regarding the function of CacyBP/SIP, there are some reports suggesting its role in cellular processes such as ubiquitination, proliferation, differentiation, tumorigenesis, cytoskeletal rearrangement or regulation of transcription. This review describes the properties of CacyBP/SIP and summarizes all findings concerning its cellular function.

Proteomic profiling in distinct cellular compartments of tumor cells reveals p53-dependent upregulation of S100A6 upon induction of telomere dysfunction

Telomere dysfunction is evoking a DNA damage response which leads to replicative senescence or apoptosis. Tumor cells feature telomerase, a ribonucleoprotein complex counteracting telomere shortening and proliferation limitation as a prerequisite of immortal cell growth. Recently, we demonstrated the effects of telomerase inhibition on the proteome of tumor cell clones in whole cell lysates by SELDI-TOF-MS profiling and MS/MS protein identification (Zimmermann et al., Proteomics 2009, 9, 521-534). We continued proteomic analyses of such clones after telomerase-inhibition using fractionation of cellular compartments. Among the differentially expressed peaks found in different fractions, a cytoplasmic 10.1 kDa protein upregulated in telomerase-inhibited clones (p<0.0001) was identified by nanoflow-HPLC-MS/MS as S100A6. S100A6 upregulation was confirmed by immunoblotting in telomerase-inhibited HCT-116, A-549, and NCI-H460 clones. S100A6 and other proteins involved in telomere dysfunction were further analyzed in derivative p53(-/-) and p21(-/-) HCT-116 cell lines indicating an overall reduced number of significant changes in these lines compared to wild type HCT-116 cells. In addition, post-translational modification of S100A6 was demonstrated with a potential role in mediating the cellular response to telomere dysfunction. In conclusion, proteomic profiling in distinct cellular compartments led to the identification of a novel p53-dependent biomarker of telomere dysfunction, S100A6.

Serum S100A6 concentration predicts peritoneal tumor burden in mice with epithelial ovarian cancer and is associated with advanced stage in patients

BACKGROUND

Ovarian cancer is the 5th leading cause of cancer related deaths in women. Five-year survival rates for early stage disease are greater than 94%, however most women are diagnosed in advanced stage with 5 year survival less than 28%. Improved means for early detection and reliable patient monitoring are needed to increase survival.

METHODOLOGY AND PRINCIPAL FINDINGS

Applying mass spectrometry-based proteomics, we sought to elucidate an unanswered biomarker research question regarding ability to determine tumor burden detectable by an ovarian cancer biomarker protein emanating directly from the tumor cells. Since aggressive serous epithelial ovarian cancers account for most mortality, a xenograft model using human SKOV-3 serous ovarian cancer cells was established to model progression to disseminated carcinomatosis. Using a method for low molecular weight protein enrichment, followed by liquid chromatography and mass spectrometry analysis, a human-specific peptide sequence of S100A6 was identified in sera from mice with advanced-stage experimental ovarian carcinoma. S100A6 expression was documented in cancer xenografts as well as from ovarian cancer patient tissues. Longitudinal study revealed that serum S100A6 concentration is directly related to tumor burden predictions from an inverse regression calibration analysis of data obtained from a detergent-supplemented antigen capture immunoassay and whole-animal bioluminescent optical imaging. The result from the animal model was confirmed in human clinical material as S100A6 was found to be significantly elevated in the sera from women with advanced stage ovarian cancer compared to those with early stage disease.

CONCLUSIONS

S100A6 is expressed in ovarian and other cancer tissues, but has not been documented previously in ovarian cancer disease sera. S100A6 is found in serum in concentrations that correlate with experimental tumor burden and with clinical disease stage. The data signify that S100A6 may prove useful in detecting and/or monitoring ovarian cancer, when used in concert with other biomarkers.

Proteomics in thyroid tumor research

BACKGROUND

In recent years, "OMICS" technologies have paved novel ways for the broad-scale identification of molecular signatures and signaling pathways specific to tumorigenesis. Related to this are high hopes for the discovery of biomarkers facilitating diagnosis and prognosis of cancer as well as the option for pathway-targeted tumor treatment. Among the different OMICS methods, the potential of proteomics is just beginning to emerge, and according to the current literature, the proteome is to date the most feasible tool to reflect tumor biology.

OBJECTIVE

In this review we discuss the application of proteomics to the field of thyroid tumor research.

CONTEXT

First, we provide an overview of different methods for protein expression profiling and then discuss specific requirements and challenges of thyroid proteomics. Furthermore, we summarize results of published proteomics studies on human thyroid tumors and finally explore perspectives of thyroid proteomics, which, combined with mRNA expression profiling and traditional biochemical methods, is increasingly contributing to an improved understanding of thyroid tumorigenesis and may in the future open novel avenues in thyroid cancer therapy.