Differential expression of S100A2 and S100A4 in lung adenocarcinomas: clinicopathological significance, relationship to p53 and identification of their target genes

Influence of S100A2 in Human Diseases

S100 proteins are a family of low-molecular-weight proteins characterized by two calcium-binding sites with a helix-loop-helix (“EF-hand-type”) domain. The S100 family of proteins is distributed across various organs and can interact with diverse molecules. Among the proteins of the S100 family, S100 calcium-binding protein A2 (S100A2) has been identified in mammary epithelial cells, glands, lungs, kidneys, and prostate gland, exhibiting various physiological and pathological actions in human disorders, such as inflammatory diseases and malignant tumors. In this review, we introduce basic knowledge regarding S100A2 regulatory mechanisms. Although S100A2 is a tumor suppressor, we describe the various influences of S100A2 on cancer and inflammatory diseases.

Association of Angiogenesis Gene Expression With Cancer Prognosis and Immunotherapy Efficacy

Background: Several new blood vessels are formed during the process of tumor development. These new blood vessels provide nutrients and water for tumour growth, while spreading tumour cells to distant areas and forming new metastases in different parts of the body. The available evidence suggests that tumour angiogenesis is closely associated with the tumour microenvironment and is regulated by a variety of pro-angiogenic factors and/or angiogenic inhibitors.

Methods: In the present study, a comprehensive characterization of angiogenesis genes expression was performed in a pan-cancer analysis across the 33 human cancer types. Further, genetic data from several public databases were also used in the current study. An angiogenesis score was assigned to The Cancer Genome Atlas (TCGA) pan-cancer data, with one angiogenesis score as per sample for each tumour.

Results: It was found that angiogenesis genes vary across cancer types, and are associated with a number of genomic and immunological features. Further, it was noted that macrophages and iTreg infiltration were generally higher in tumours with high angiogenesis scores, whereas lymphocytes and B cells showed the opposite trend. Notably, NK cells showed significantly different correlations among cancer types. Furthermore, results of the present study showed that a high angiogenesis score was associated with poor survival and aggressive types of cancer in most of the cancer types.

Conclusion: In conclusion, the current study evidently showed that the expression of angiogenesis genes is a key feature of tumour biology that has a major impact on prognosis of patient with cancers.

Alterations in the Ca2+ toolkit in oesophageal adenocarcinoma

Aim:

To investigate alterations in transcription of genes, encoding Ca²⁺ toolkit proteins, in oesophageal adenocarcinoma (OAC) and to assess associations between gene expression, tumor grade, nodal-metastatic stage, and patient survival.

Methods:

The expression of 275 transcripts, encoding components of the Ca²⁺ toolkit, was analyzed in two OAC datasets: the Cancer Genome Atlas [via the University of Alabama Cancer (UALCAN) portal] and the oesophageal-cancer, clinical, and molecular stratification [Oesophageal Cancer Clinical and Molecular Stratification (OCCAMS)] dataset. Effects of differential expression of these genes on patient survival were determined using Kaplan-Meier log-rank tests. OAC grade- and metastatic-stage status was investigated for a subset of genes. Adjustment for the multiplicity of testing was made throughout.

Results:

Of the 275 Ca²⁺-toolkit genes analyzed, 75 displayed consistent changes in expression between OAC and normal tissue in both datasets. The channel-encoding genes, N-methyl-D-aspartate receptor 2D (GRIN2D), transient receptor potential (TRP) ion channel classical or canonical 4 (TRPC4), and TRP ion channel melastatin 2 (TRPM2) demonstrated the greatest increase in expression in OAC in both datasets. Nine genes were consistently upregulated in both datasets and were also associated with improved survival outcomes. The 6 top-ranking genes for the weighted significance of altered expression and survival outcomes were selected for further analysis: voltage-gated Ca²⁺ channel subunit α 1D (CACNA1D), voltage-gated Ca²⁺ channel auxiliary subunit α2 δ4 (CACNA2D4), junctophilin 1 (JPH1), acid-sensing ion channel 4 (ACCN4), TRPM5, and secretory pathway Ca²⁺ ATPase 2 (ATP2C2). CACNA1D, JPH1, and ATP2C2 were also upregulated in advanced OAC tumor grades and nodal-metastatic stages in both datasets.

Conclusions:

This study has unveiled alterations of the Ca²⁺ toolkit in OAC, compared to normal tissue. Such Ca²⁺ signalling findings are consistent with those from studies on other cancers. Genes that were consistently upregulated in both datasets might represent useful markers for patient diagnosis. Genes that were consistently upregulated, and which were associated with improved survival, might be useful markers for patient outcome. These survival-associated genes may also represent targets for the development of novel chemotherapeutic agents.

Clinicopathological and prognostic value of S100A4 expression in non-small cell lung cancer: a meta-analysis

Background: Numerous published studies have shown that S100A4 is frequently overexpressed in various human cancers. However, the association between S100A4 expression and prognosis or clinicopathological parameters in non-small cell lung cancer (NSCLC) remains unclear. Therefore, a meta-analysis was performed to identify the significance of S100A4 in NSCLC.

Methods: Systematic literature search was conducted using PubMed, Embase, Web of Science, the Cochrane Library, the Chinese National Knowledge Infrastructure database (CNKI), and the Wanfang database to obtain relevant articles. A combined hazard ratio (HR) and its corresponding 95% confidence interval (CI) were used to evaluate the association between S100A4 expression and prognosis in NSCLC patients. Pooled odds ratio (OR) and 95% CI were calculated to assess the association between S100A4 expression and clinicopathological features in NSCLC.

Results: NSCLC patients with overexpression of S100A4 had a worse prognosis than patients with low expression of S100A4 (HR = 1.77, 95% CI: 1.55–2.02, P<0.001). Additionally, overexpression of S100A4 was significantly correlated to patients’ age (OR = 0.67, 95% CI: 0.49–0.91, P=0.010), tumor differentiation (OR = 2.20, 95% CI: 1.69–2.85, P<0.001), lymph node metastasis (LNM) (OR = 3.70, 95% CI: 2.25–6.06, P<0.001), Tumor-Node-Metastasis (TNM) stage (OR = 3.08, 95% CI: 2.10–4.53, P<0.001), and pathological subtype (OR = 1.77, 95% CI: 1.09–2.88, P=0.020). However, there was no association between S100A4 expression and other clinicopathological features in NSCLC, including gender, tumor size, and smoking.

Conclusion: S100A4 overexpression was associated with tumor progression and poor prognosis in NSCLC patients. Hence, S100A4 might serve as a potential prognostic biomarker in NSCLC.

CCN Family Proteins in Cancer: Insight Into Their Structures and Coordination Role in Tumor Microenvironment

The crosstalk between tumor cells and the tumor microenvironment (TME), triggers a variety of critical signaling pathways and promotes the malignant progression of cancer. The success rate of cancer therapy through targeting single molecule of this crosstalk may be extremely low, whereas co-targeting multiple components could be complicated design and likely to have more side effects. The six members of cellular communication network (CCN) family proteins are scaffolding proteins that may govern the TME, and several studies have shown targeted therapy of CCN family proteins may be effective for the treatment of cancer. CCN protein family shares similar structures, and they mutually reinforce and neutralize each other to serve various roles that are tightly regulated in a spatiotemporal manner by the TME. Here, we review the current knowledge on the structures and roles of CCN proteins in different types of cancer. We also analyze CCN mRNA expression, and reasons for its diverse relationship to prognosis in different cancers. In this review, we conclude that the discrepant functions of CCN proteins in different types of cancer are attributed to diverse TME and CCN truncated isoforms, and speculate that targeting CCN proteins to rebalance the TME could be a potent anti-cancer strategy.

Tumor-Suppressor p53TAD1-60 Forms a Fuzzy Complex with Metastasis-Associated S100A4: Structural Insights and Dynamics by an NMR/MD Approach

Conformationally flexible protein complexes represent a major challenge for structural and dynamical studies. We present herein a method based on a hybrid NMR/MD approach to characterize the complex formed between the disordered p53TAD1-60 and the metastasis-associated S100A4. Disorder-to-order transitions of both TAD1 and TAD2 subdomains upon interaction is detected. Still, p53TAD1-60 remains highly flexible in the bound form, with residues L26, M40, and W53 being anchored to identical hydrophobic pockets of the S100A4 monomer chains. In the resulting "fuzzy" complex, the clamp-like binding of p53TAD1-60 relies on specific hydrophobic anchors and on the existence of extended flexible segments. Our results demonstrate that structural and dynamical NMR parameters (cumulative Δδ, SSP, temperature coefficients, relaxation time, hetNOE) combined with MD simulations can be used to build a structural model even if, due to high flexibility, the classical solution structure calculation is not possible.

Pentamidine inhibit S100A4 - p53 interaction and decreases cell proliferation activity

Metastasis-associated S100A4 protein is a small calcium-binding protein typically overexpressed in several tumor forms, and it is widely accepted that S100A4 plays a significant role in the metastasis of cancer. Tumor suppressor p53 is one of the S100A4's main targets. Previous reports show that through p53, S100A4 regulates collagen expression and cell proliferation. When S100A4 interacts with p53, the S100A4 destabilizes wild type p53. In the current study, based on ¹H-¹⁵N HSQC NMR experiments and HADDOCK results, S100A4 interacts with the intrinsically unstructured transactivation domain (TAD) of the protein p53 and the pentamidine molecules in the presence of calcium ions. Our results suggest that the p53 TAD and pentamidine molecules share similar binding sites on the S100A4 protein. This observation indicates that a competitive binding mechanism can interfere with the binding of S100A4-p53 and increase the level of p53. Also, we compare different aspects of p53 activity in the WST-1 test using MCF 7 cells. We found that the presence of a pentamidine molecule results in higher p53 activity, which is also reflected in less cell proliferation. Collectively, our results indicate that disrupting the S100A4-p53 interaction would prevent cancer progression, and thus S100A4-p53 inhibitors provide a new avenue for cancer therapy.

Cul4A Modulates Invasion and Metastasis of Lung Cancer Through Regulation of ANXA10

: Cullin 4A (Cul4A) is overexpressed in a number of cancers and has been established as an oncogene. This study aimed to elucidate the role of Cul4A in lung cancer invasion and metastasis. We observed that Cul4A was overexpressed in non-small cell lung cancer (NSCLC) tissues and the overexpression of Cul4A was associated with poor prognosis after surgical resection and it also decreased the expression of the tumor suppressor protein annexin A10 (ANXA10). The knockdown of Cul4A was associated with the upregulation of ANXA10, and the forced expression of Cul4A was associated with the downregulation of ANXA10 in lung cancer cells. Further studies showed that the knockdown of Cul4A inhibited the invasion and metastasis of lung cancer cells, which was reversed by the further knockdown of ANXA10. In addition, the knockdown of Cul4A inhibited lung tumor metastasis in mouse tail vein injection xenograft models. Notably, Cul4A regulated the degradation of ANXA10 through its interaction with ANXA10 and ubiquitination in lung cancer cells. Our findings suggest that Cul4A is a prognostic marker in NSCLC patients, and Cul4A plays important roles in lung cancer invasion and metastasis through the regulation of the ANXA10 tumor suppressor.

The emerging role of WISP proteins in tumorigenesis and cancer therapy

Accumulated evidence has demonstrated that WNT1 inducible signaling pathway protein (WISP) genes, which belong to members of the CCN growth factor family, play a pivotal role in tumorigenesis and progression of a broad spectrum of human cancers. Mounting studies have identified that WISP proteins (WISP1-3) exert different biological functions in various human malignancies. Emerging evidence indicates that WISP proteins are critically involved in cell proliferation, apoptosis, invasion and metastasis in cancers. Because the understanding of a direct function of WISP proteins in cancer development and progression has begun to emerge, in this review article, we describe the physiological function of WISP proteins in a variety of human cancers. Moreover, we highlight the current understanding of how the WISP protein is involved in tumorigenesis and cancer progression. Furthermore, we discuss that targeting WISP proteins could be a promising strategy for the treatment of human cancers. Hence, the regulation of WISP proteins could improve treatments for cancer patients.

S100A4 drives non-small cell lung cancer invasion, associates with poor prognosis, and is effectively targeted by the FDA-approved anti-helminthic agent niclosamide

S100A4 (metastasin-1), a metastasis-associated protein and marker of the epithelial to mesenchymal transition, contributes to several hallmarks of cancer and has been implicated in the progression of several types of cancer. However, the impacts of S100A4 signaling in lung cancer progression and its potential use as a target for therapy in lung cancer have not been properly explored. Using established lung cancer cell lines, we demonstrate that S100A4 knockdown reduces cell proliferation, invasion and three-dimensional invasive growth, while overexpression of S100A4 increases invasive potential. In patient-derived tissues, S100A4 is preferentially elevated in lung adenocarcinoma. This elevation is associated with lymphovascular invasion and decreased overall survival. In addition, depletion of S100A4 by shRNA inhibits NF-κB activity and decreases TNFα-induced MMP9 expression. Furthermore, inhibition of the NF-κB/MMP9 axis decreases lung carcinoma invasive potential. Niclosamide, a reported inhibitor of S100A4, blocks expression and function of S100A4 with a reduction in proliferation, invasion and NF-κB-mediated MMP9 expression. Collectively, this study highlights the importance of the S100A4/NF-κB/MMP9 axis in lung cancer invasion and provides a rationale for targeting S100A4 to combat lung cancer.

Helicobacter pylori outer inflammatory protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro

Outer inflammatory protein A (OipA) is an important virulence factor associated with gastric cancer and ulcer development; however, the results have not been well established and turned out to be controversial. This study aims to elucidate the role of OipA in Helicobacter pylori infection using clinical strains harbouring oipA "on" and "off" motifs. Proteomics analysis was performed on AGS cell pre-infection and postinfection with H. pylori oipA "on" and "off" strains, using liquid chromatography/mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down-regulated postinfection with oipA "off" strains comparing to oipA "on" strains. Furthermore, oipA "off" and ΔoipA cause higher level of AGS cells apoptosis and G0/G1 cell-cycle arrest than oipA "on" strains. Interestingly, deletion of oipA increased bacterial VacA production. The capability of H. pylori to induce apoptosis and suppress expression of proteins having roles in human disease in the absence of oipA suggests that strains not expressing OipA may be less virulent or may even be protective against carcinogenesis compared those expressing OipA. This potentially explains the higher incidence of gastric cancer in East Asia where oipA "on" strains predominates.

Simvastatin Up-Regulates Annexin A10 That Can Inhibit the Proliferation, Migration, and Invasion in Androgen-Independent Human Prostate Cancer Cells

BACKGROUND

Statins have recently been studied for their proapoptotic and antimetastatic effects. However, the exact mechanisms of their anticancer actions remain unclear. Using microarrays, we discovered up-regulation of annexin A10 (ANXA10) in PC-3 cells after simvastatin treatment. ANXA10 reportedly has antitumor effects. In this study, we evaluated the effects of simvastatin on ANXA10 signaling in androgen-independent prostate cancer cells.

METHODS

PC-3, LNCaP-LA (which were derived from LNCaP cells and cultured in 10% charcoal-stripped fetal bovine serum for 3 months), and DU145 human prostate cancer cell lines were used. Prostate tissues were collected from 60 patients (benign prostatic hyperplasia [BPH], n = 20; prostate cancer with a Gleason score of 7, n = 20; prostate cancer with a Gleason score of 8-10, n = 20) at the time of prostate biopsies performed. We used a nude mouse tumor xenograft model with administration of simvastatin or phosphate-buffered saline via intraperitoneal injection.

RESULTS

Simvastatin inhibited the proliferation, migration, and invasion of PC-3, LNCaP-LA, and DU145 cells. The expression level of ANXA10 was up-regulated by simvastatin in PC-3, LNCaP-LA, and DU145 cells. Transfection with ANXA10 inhibited PC-3 and LNCaP-LA cells proliferation, migration, and invasion. Knockdown of ANXA10 by siRNA increased the proliferation of PC-3 and LNCaP-LA cells. In a nude mouse xenograft model of PC-3 cells, simvastatin induced both reduction in the tumor size and up-regulation of ANXA10 expression. In human prostate biopsy samples, ANXA10 mRNA expression was significantly lower in the prostate cancer group than in the BPH group. Next, we found that up-regulation of ANXA10 in PC-3 resulted in down-regulation of S100 calcium binding protein A4 (S100A4), which is reportedly correlated with aggressiveness and a worse prognosis for patients with different types of carcinomas. Expression of S100A4 was down-regulated by simvastatin. In PC-3 cells, knockdown of S100A4 by siRNA inhibited the proliferation, migration, and invasion of PC-3 cells.

CONCLUSION

Our results suggest that statins inhibit the proliferation, migration, and invasion of androgen-independent prostate cancer cells by up-regulation of ANXA10. Additionally, it is possible that S100A4 plays a role in these effects. Statins may be beneficial in the prevention and/or treatment of prostate cancer. Prostate 77: 337-349, 2017. © 2016 Wiley Periodicals, Inc.

Expression and clinicopathological significance of S100 calcium binding protein A2 in lung cancer patients of Chinese Han ethnicity

BACKGROUND

S100 family of calcium-binding proteins plays a significant role in the process of many kinds of tumors, including lung cancer. As an important member of this family, S100 calcium binding protein A2 (S100A2) has been confirmed to be associated with many biological processes, and has an abnormal expression in non-small cell lung cancer (NSCLC). However, the S100A2 status in lung cancer is still controversial and undefined.

METHODS

We evaluated the pattern and distribution of S100A2 in 109 cases of lung cancer, including five histological types (47 adenocarcinoma, 46 squamous cell carcinoma, 7 small cell carcinoma, 3 large cell carcinoma, and 6 atypical carcinoid), and 30 cases of paired adjacent normal lung tissues by means of immunohistochemistry.

RESULTS

Compared with the normal tissues (0/30), S100A2 experienced a dramatically upward trend of positive expression in lung cancer, with a positive rate of 68/109 (P<0.001). Specifically, squamous cell carcinoma, with 34/12, had the highest expression ratio, followed by large cell carcinoma (2/1), adenocarcinoma (31/16), and atypical carcinoid (1/5) respectively, while no S100A2 protein was detected in small cell carcinoma. Meanwhile, we firstly demonstrated that the high expression of S100A2 was significantly associated with the incidence of lymph node metastasis in adenocarcinoma (P=0.013).

CONCLUSIONS

The association between high S100A2 expression and NSCLC at the level of tissue, and S100A2 may serve as an effective biomarker for the diagnosis and prognosis of NSCLC in future.

S100A4 protects the myocardium against ischemic stress

BACKGROUND

Myocardial infarction is followed by cardiac dysfunction, cellular death, and ventricular remodeling, including tissue fibrosis. S100A4 protein plays multiple roles in cellular survival, and tissue fibrosis, but the relative role of the S100A4 in the myocardium after myocardial infarction is unknown. This study aims to investigate the role of S100A4 in myocardial remodeling and cardiac function following infarct damage.

METHODS AND RESULTS

S100A4 expression is low in the adult myocardium, but significantly increased following myocardial infarction. Deletion of S100A4 increased cardiac damage after myocardial infarction, whereas cardiac myocyte-specific overexpression of S100A4 protected the infarcted myocardium. Decreased cardiac function in S100A4 Knockout mice was accompanied with increased cardiac remodeling, fibrosis, and diminished capillary density in the remote myocardium. Loss of S100A4 caused increased apoptotic cell death both in vitro and in vivo in part mediated by decreased VEGF expression. Conversely, S100A4 overexpression protected cells against apoptosis in vitro and in vivo. Increased pro-survival AKT-signaling explained reduced apoptosis in S100A4 overexpressing cells.

CONCLUSION

S100A4 expression protects cardiac myocytes against myocardial ischemia and is required for stabilization of cardiac function after MI.

A five-gene expression signature to predict progression in T1G3 bladder cancer

OBJECTIVE

The aim of this study was to analyze tumour gene expression profiles of progressive and non-progressive T1G3 bladder cancer (BC) patients to develop a gene expression signature to predict tumour progression.

METHODS

Retrospective, multicenter study of 96 T1G3 BC patients without carcinoma in situ (CIS) who underwent a transurethral resection. Formalin-fixed paraffin-embedded tissue samples were collected. Global gene expression patterns were analyzed in 21 selected samples from progressive and non-progressive T1G3 BC patients using Illumina microarrays. Expression levels of 94 genes selected based on microarray data and based on literature were studied by quantitative polymerase chain reaction (qPCR) in an independent series of 75 progressive and non-progressive T1G3 BC patients. Univariate logistic regression was used to identify individual predictors. A variable selection method was used to develop a multiplex biomarker model. Discrimination of the model was measured by area under the receiver-operating characteristic curve. Interaction networks between the genes of the model were built by GeneMANIA Cytoscape plugin.

RESULTS

A total of 1294 genes were found differentially expressed between progressive and non-progressive patients. Differential expression of 15 genes was validated by qPCR in an additional set of samples. A five-gene expression signature (ANXA10, DAB2, HYAL2, SPOCD1, and MAP4K1) discriminated progressive from non-progressive T1G3 BC patients with a sensitivity of 79% and a specificity of 86% (AUC = 0.83). Direct interactions between the five genes of the model were not found.

CONCLUSIONS

Progressive and non-progressive T1G3 bladder tumours have shown different gene expression patterns. To identify T1G3 BC patients with a high risk of progression, a five-gene expression signature has been developed.

Altered gene expression in conjunctival squamous cell carcinoma

Conjunctival squamous cell carcinoma is a malignancy of the ocular surface. The molecular drivers responsible for the development and progression of this disease are not well understood. We therefore compared the transcriptional profiles of eight snap-frozen conjunctival squamous cell carcinomas and one in situ lesion with normal conjunctival specimens in order to identify diagnostic markers or therapeutic targets. RNA was analyzed using oligonucleotide microarrays, and a wide range of transcripts with altered expression identified, including many dysregulated in carcinomas arising at other sites. Among the upregulated genes, we observed more than 30-fold induction of the matrix metalloproteinases, MMP-9 and MMP-11, as well as a prominent increase in the mRNA level of a calcium-binding protein important for the intracellular calcium signaling, S100A2, which was induced over 20-fold in the tumor cohort. Clusterin was the most downregulated gene, with an approximately 180-fold reduction in the mRNA expression. These alterations were all confirmed by qPCR in the samples used for initial microarray analysis. In addition, immunohistochemical analysis confirmed the overexpression of MMP-11 and S100A2, as well as reductions in clusterin, in several independent in situ carcinomas of conjunctiva. These data identify a number of alterations, including upregulation of MMP-9, MMP-11, and S100A2, as well as downregulation of clusterin, associated with epithelial tumorigenesis in the ocular surface.

Up-Regulation of S100A11 in Lung Adenocarcinoma - Its Potential Relationship with Cancer Progression

We previously reported that patients with lung adenocarcinomas with KRAS gene mutations and strong proliferating activity had poorer outcomes, even in the early stage of the disease. The aim of the present study was to elucidate the potential molecular basis of these highly malignant lung tumors by focusing on S100 proteins (S100A2, S100A7, and S100A11), which are downstream targets of oncogenic KRAS and promoters of tumor progression. The immunohistochemical expression of S100 proteins was examined in 179 primary lung adenocarcinomas, and the potential relationships between their levels and clinicopathologic factors were analyzed. Among the three subtypes, S100A11 levels were significantly higher in adenocarcinomas with KRAS mutations and strong proliferating activity. They were also higher in adenocarcinomas with poorly differentiated tumors. Furthermore, higher levels of S100A11 were associated with shorter disease-free survival. These results suggest that the up-regulation of S100A11 plays a role in tumor progression, particularly in KRAS-mutated lung adenocarcinomas.

Epigenetic silencing of S100A2 in bladder and head and neck cancers

S100A2, a member of the S100 protein family, is known to be downregulated in a number of human cancers, leading to its designation as a potential tumor suppressor gene. Here, we investigated the expression and methylation status of S100A2 in head&neck and bladder cancer. Reduced mRNA and protein expression was observed in 8 head&neck and bladder cancer cell lines. To explore the mechanism responsible for the downregulation of S100A2, we treated six cell lines with 5-aza-2'-deoxycytidine. We found S100A2 is silenced in association with aberrant promoter-region methylation and its expression is restored with 5-aza-2'-deoxycytidine treatment. Of 31 primary head&neck cancer cases and 31 bladder cancer cases, promoter methylation was detected in 90% and 80% of cases, respectively. Interestingly, only 1/9 of normal head&neck tissues and 2/6 of normal bladder tissues showed promoter methylation. S100A2 promoter methylation can be detected in urine and is more frequent in bladder cancer patients than in healthy subjects (96% vs 48% respectively). Moreover, increased methylation of S100A2 is linked to the progression of the tumor in bladder cancer (p<0.01). Together, this data shows that methylation-associated inactivation of S100A2 is frequent and may be an important event in the tumorigenesis of head&neck and bladder cancer.

S100A4 is an independent prognostic factor for patients with lung cancer: a meta-analysis

OBJECTIVE

To evaluate the association of S100A4 levels with the prognosis of lung cancer (LC).

METHODS

The RevMan 5.0 software was utilized to perform literature retrieval, data collection, and statistical analysis according to its guidelines. Literature-based searching was guided to gather data, and the fixed-effect model was used to pool the hazard ratio (HR) in this study.

RESULTS

A total of 10 eligible studies that included 1364 LC patients were analyzed. About 72.6% of patients had positive expression of S100A4 according to the criteria defined by the authors. The HR of positive expression for overall survival (OS) was 1.30 times of that of negative expression in LC patients (HR=1.30, 95% confidence interval: 1.04 to 1.61, p=0.02).

CONCLUSION

Patients with positive expression of S100A4 appear to have a poorer OS compared with those with negative expression of S100A4.

S100A4 is frequently overexpressed in lung cancer cells and promotes cell growth and cell motility

S100A4, a small calcium-binding protein belonging to the S100 protein family, is commonly overexpressed in a variety of tumor types and is widely accepted to associate with metastasis by regulating the motility and invasiveness of cancer cells. However, its biological role in lung carcinogenesis is largely unknown. In this study, we found that S100A4 was frequently overexpressed in lung cancer cells, irrespective of histological subtype. Then we performed knockdown and forced expression of S100A4 in lung cancer cell lines and found that specific knockdown of S100A4 effectively suppressed cell proliferation only in lung cancer cells with S100A4-overexpression; forced expression of S100A4 accelerated cell motility only in S100A4 low-expressing lung cancer cells. PRDM2 and VASH1, identified as novel upregulated genes by microarray after specific knockdown of S100A4 in pancreatic cancer, were also analyzed, and we found that PRDM2 was significantly upregulated after S100A4-knockdown in one of two analyzed S100A4-overexpressing lung cancer cells. Our present results suggest that S100A4 plays an important role in lung carcinogenesis by means of cell proliferation and motility by a pathway similar to that in pancreatic cancer.

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.

The expression of S100A4 in human pancreatic cancer is associated with invasion

OBJECTIVES

Pancreatic cancer is one of the most lethal malignancies; its poor prognosis is strongly associated with invasion and metastasis. Expression of S100A4 has been reported to correlate with poor prognosis in various cancers. We have investigated the role of S100A4 in pancreatic cancer tumorigenesis and its clinicopathologic significance.

METHODS

Protein expression of S100A4 was examined by Western blot in pancreatic cancer cell lines and a human pancreatic ductal epithelium cell line, HPDE-6. Then the expressions of S100A4, TP53, and CD133 were examined immunohistochemically in resected specimens from 83 patients with pancreatic cancer to clarify their clinicopathologic significance. Survival analyses were performed using the Kaplan-Meier method and the Mantel-Cox method.

RESULTS

Forty-eight (58%) of 83 patients with pancreatic cancer positively expressed S100A4, and 50 (60%) and 29 (36%) patients positively expressed TP53 and CD133, respectively. S100A4 expression was significantly correlated with perineural invasion (P = 0.029) and invasion pattern (P = 0.001). Neither TP53 nor CD133 expression showed significant correlations with any other parameters.

CONCLUSIONS

Our present results suggest that S100A4 plays an important role in the invasiveness, particularly with perineural invasion and invasion pattern, of pancreatic cancer. Development of new strategies targeting S100A4 or its downstream effectors is warranted.

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.

S100A2 is a predictive biomarker of adjuvant therapy benefit in pancreatic adenocarcinoma

BACKGROUND

Prognosis of patients with pancreatic adenocarcinoma (PAC) remains poor. S100A2 has been recently suggested as a negative prognostic biomarker in PAC. We aimed to investigate its prognostic and/or predictive value in a large independent multicentric cohort of patients with resected PAC.

METHODS

Sequential samples of 471 patients were retrospectively collected; 142 patients did not receive adjuvant treatment (30%) and 329 (70%) received an adjuvant treatment. We measured protein levels of S100A2 by semiquantitative immunohistochemistry with tissue microarrays and correlated with patients' overall survival (OS) and disease-free survival (DFS).

RESULTS

S100A2 protein status was obtained in 462 (98%) patients. Its expression was low, moderate or high in 59%, 12% and 2% of cases, respectively. It was not correlated with DFS or OS in the whole population, neither in the subgroup of patients who did not receive adjuvant treatment. However among patients who received an adjuvant therapy, moderate/high levels of S100A2 were significantly associated with longer OS and DFS in multivariate analysis (hazard ratios of 0.63, p=0.022 and 0.67, p=0.017, respectively), whereas low S100A2 was not. Interaction tests for adjuvant therapy were statistically significant both for the OS and the DFS (p=0.001 and p=0.023, respectively). On multivariate analysis, S100A2 retained independent predictive values (OS: p<0.001, DFS: p=0.003) with a significant benefit of adjuvant therapy for those patients with moderate/high S100A2.

CONCLUSIONS

S100A2 expression predicts longer DFS and OS in patients treated with adjuvant therapy and should be evaluated as a predictive biomarker.

Clinical significance of altered S100A2 expression in gastric cancer

The S100A2 gene has been reported to be a putative tumor‑suppressor gene. Nevertheless, overexpression of S100A2 has been found in certain types of cancer. This study investigated S100A2 expression in tissue specimens of gastritis, intestinal metaplasia, adenomatous dysplasia and gastric cancer to determine its association with clinical features. A serial of tissue samples (gastritis, intestinal metaplasia, adenomatous dysplasia and gastric cancer samples) were used for quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR), western blotting and immunohistochemical analyses of S100A2 expression. The data revealed that there was a gradual loss of S100A2 expression from gastritis, intestinal metaplasia and dysplasia to cancer tissue specimens (p<0.001). In gastric cancer samples, loss of S100A2 expression was associated with increased tumor size, depth of invasion, lymph node metastasis and a poor prognosis (p<0.001). However, the intestinal type of gastric cancer expressed more S100A2 protein than the diffuse type (p<0.001). In conclusion, data from the present study demonstrated that loss of S100A2 expression contributes to gastric cancer development and progression; therefore, the determination of S100A2 expression levels may help to predict the carcinogenesis and aggressiveness of gastric cancer as well as patient survival.

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.

S100A2 promoter-driven conditionally replicative adenovirus targets non-small-cell lung carcinoma

S100A2, a member of the S100 family of calcium-binding proteins, has been implicated in carcinogenesis as both a tumor suppressor and stimulator. Here, we characterized promoter activity of S100A2, generated an S100A2 promoter-driven conditionally replicative adenovirus (Ad/SA), and evaluated its anti-tumor activity in vitro and in vivo. Promoter activity of S100A2 was greatly restricted to tumor cells, and the S100A2 promoter bound with typical nuclear targets of epidermal growth factor receptor (EGFR) signaling. EGF-stimulated EGFR phosphorylation induced S100A2 expression and further activated E1A expression of Ad/SA, which was restored by EGFR signal inhibition in a concentration-dependent manner in non-small-cell lung carcinoma (NSCLC). In two EGFR-activated tumor xenograft animal models, Ad/SA exhibited potent anti-tumor activity, whereas cetuximab, an EGFR-targeting anticancer drug, was active transiently or ineffective. Combined treatment with cetuximab or cisplatin plus Ad/SA resulted in enhanced anti-tumor activity. Immunohistochemical analysis of tumor sections showed moderate-to-high grade signals for EGFR and adenovirus, and a reduction in viable cells in Ad/SA-treated tumors. Collectively, these results demonstrate that the S100A2 promoter-driven adenovirus is a potent inhibitor of cancers, and further suggest that S100A2 is a target gene of EGFR signaling pathway in NSCLC.

Low ANXA10 expression is associated with disease aggressiveness in bladder cancer

Background:

Markers for outcome prediction in bladder cancer are urgently needed. We have previously identified a molecular signature for predicting progression in non-muscle-invasive bladder cancer. ANXA10 was one of the markers included in the signature and we now validated the prognostic relevance of ANXA10 at the protein level.

Methods:

We investigated ANXA10 expression by immunohistochemistry using a tissue microarray with 249 Ta and T1 urothelial carcinomas. The expression of ANXA10 was also investigated in an additional set of 97 more advanced tumours. The functional role of ANXA10 in cell lines was investigated by siRNA-mediated ANXA10 knockdown using wound-healing assays, proliferation assays, and ingenuity pathway analysis.

Results:

Low expression of ANXA10 correlated with shorter progression-free survival in patients with stage Ta and T1 tumours (P<0.00001). Furthermore, patients with more advanced tumours and low ANXA10 expression had an unfavourable prognosis (P<0.00001). We found that ANXA10 siRNA transfected cells grew significantly faster compared with control siRNA transfected cells. Furthermore, a wound-healing assay showed that ANXA10 siRNA transfected cells spread along wound edges faster than control transfected cells.

Conclusion:

We conclude that ANXA10 may be a clinical relevant marker for predicting outcome in both early and advanced stages of bladder cancer.

Senescent cells develop a PARP-1 and nuclear factor-{kappa}B-associated secretome (PNAS)

Melanoma cells can enter the process of senescence, but whether they express a secretory phenotype, as reported for other cells, is undetermined. This is of paramount importance, because this secretome can alter the tumor microenvironment and the response to chemotherapeutic drugs. More generally, the molecular events involved in formation of the senescent-associated secretome have yet to be determined. We reveal here that melanoma cells experiencing senescence in response to diverse stimuli, including anti-melanoma drugs, produce an inflammatory secretory profile, where the chemokine ligand-2 (CCL2) acts as a critical effector. Thus, we reveal how senescence induction might be involved in therapeutic failure in melanoma. We further provide a molecular relationship between senescence induction and secretome formation by revealing that the poly(ADP-ribose) polymerase-1 (PARP-1)/nuclear factor-κB (NF-κB) signaling cascade, activated during senescence, drives the formation of a secretome endowed with protumoral and prometastatic properties. Our findings also point to the existence of the PARP-1 and NF-κB-associated secretome, termed the PNAS, in nonmelanoma cells. Most importantly, inhibition of PARP-1 or NF-κB prevents the proinvasive properties of the secretome. Collectively, identification of the PARP-1/NF-κB axis in secretome formation opens new avenues for therapeutic intervention against cancers.

Loss of Reprimo and S100A2 expression in human gastric adenocarcinoma

Reprimo and S100A2 are two newly identified candidate tumor-suppressor genes, which play an important role in the regulation of p53-dependent cell cycle. In this study, we examined the expressions of Reprimo and S100A2 in surgical specimens of gastric adenocarcinoma and correlated these results with pathological and clinical parameters. Tissues were obtained from 100 gastric adenocarcinoma patients that underwent curative gastrectomy. Reprimo and S100A2 expressions were evaluated by immunohistochemical analysis. Loss of Reprimo and S100A2 expressions occurred in 65 and 52% of the patients, respectively. Loss of Reprimo expression was significantly correlated with the depth of tumor invasion (P = 0.000), lymphatic vessel invasion (P = 0.006), and lymph node metastasis (P = 0.000). Loss of S100A2 expression was significantly associated with histological type (P = 0.009), depth of invasion (P = 0.033), lymphatic vessel invasion (P = 0.01), and lymph node metastasis (P = 0.001). In addition, there was a significant positive association between the expressions of Reprimo and S100A2 (P < 0.01). The results suggest that loss of Reprimo and S100A2 expressions occurs frequently in gastric adenocarcinomas. The expressions of Reprimo and S100A2 may be potential biomarkers for gastric adenocarcinomas detection.

S100A2 in cancerogenesis: a friend or a foe?

Owing to the exceptional intracellular distribution and the heterogeneous expression pattern during transformation and metastasis in various tumors, the EF-hand calcium-binding protein S100A2 attracts increasing attention. Unlike the majority of S100 proteins, S100A2 expression is downregulated in many cancers and the loss in nuclear expression has been associated with poor prognosis. On the other hand, S100A2 is upregulated in some cancers. This mini review highlights the general characteristics of S100A2 and discusses recent findings on its putative functional implication as a suppressor or promoter in cancerogenesis.

Self-association of calcium-binding protein S100A4 and metastasis

Elevated levels of the calcium-binding protein S100A4 promote metastasis and in carcinoma cells are associated with reduced survival of cancer patients. S100A4 interacts with target proteins that affect a number of activities associated with metastatic cells. However, it is not known how many of these interactions are required for S100A4-promoted metastasis, thus hampering the design of specific inhibitors of S100A4-induced metastasis. Intracellular S100A4 exists as a homodimer through previously identified, well conserved, predominantly hydrophobic key contacts between the subunits. Here it is shown that mutating just one key residue, phenylalanine 72, to alanine is sufficient to reduce the metastasis-promoting activity of S100A4 to 50% that of the wild type protein, and just 2 or 3 specific mutations reduces the metastasis-promoting activity of S100A4 to less than 20% that of the wild type protein. These mutations inhibit the self-association of S100A4 in vivo and reduce markedly the affinity of S100A4 for at least two of its protein targets, a recombinant fragment of non-muscle myosin heavy chain isoform A, and p53. Inhibition of the self-association of S100 proteins might be a novel means of inhibiting their metastasis-promoting activities.

Accurate molecular classification of cancer using simple rules

BACKGROUND

One intractable problem with using microarray data analysis for cancer classification is how to reduce the extremely high-dimensionality gene feature data to remove the effects of noise. Feature selection is often used to address this problem by selecting informative genes from among thousands or tens of thousands of genes. However, most of the existing methods of microarray-based cancer classification utilize too many genes to achieve accurate classification, which often hampers the interpretability of the models. For a better understanding of the classification results, it is desirable to develop simpler rule-based models with as few marker genes as possible.

METHODS

We screened a small number of informative single genes and gene pairs on the basis of their depended degrees proposed in rough sets. Applying the decision rules induced by the selected genes or gene pairs, we constructed cancer classifiers. We tested the efficacy of the classifiers by leave-one-out cross-validation (LOOCV) of training sets and classification of independent test sets.

RESULTS

We applied our methods to five cancerous gene expression datasets: leukemia (acute lymphoblastic leukemia [ALL] vs. acute myeloid leukemia [AML]), lung cancer, prostate cancer, breast cancer, and leukemia (ALL vs. mixed-lineage leukemia [MLL] vs. AML). Accurate classification outcomes were obtained by utilizing just one or two genes. Some genes that correlated closely with the pathogenesis of relevant cancers were identified. In terms of both classification performance and algorithm simplicity, our approach outperformed or at least matched existing methods.

CONCLUSION

In cancerous gene expression datasets, a small number of genes, even one or two if selected correctly, is capable of achieving an ideal cancer classification effect. This finding also means that very simple rules may perform well for cancerous class prediction.

Expression and clinical significance of S100A2 and p63 in esophageal carcinoma

AIM: To investigate the expression and clinical significance of S100A2 mRNA and protein, p63 protein in esophageal squamous cell carcinoma (ESCC) and their roles in carcinogenesis and progression of esophageal carcinoma (EC).

METHODS: Immunohistochemical staining (S-P method) for S100A2 and p63 protein were performed in 40 samples of ESCC and 40 samples of normal esophageal mucosa. In situ hybridization (ISH) was used to detect the expression of S100A2 mRNA.

RESULTS: Expression of S100A2 mRNA in ESCC was positive in 77.5% of samples, which was lower than that in normal mucosa (100%) by ISH (P = 0.002). The expression level of S100A2 mRNA was closely related to differentiation and and node-metastasis (P = 0.012, P = 0.008). Expression of S100A2 protein was positive in 72.5% of ESCC samples and expression of p63 protein was positive in 37.5% of ESCC samples, and was lower than that in normal mucosa (100%) (P = 0.000). The expression of S100A2 protein was correlated with the differentiation and node-metastasis (P = 0.007, P = 0.001), but no relationship was observed between the expression of p63 protein and clinical pathological manifestations. S100A2 protein was positively correlated with the expression of S100A2 mRNA, and negatively associated with the expression of p63 protein (P = 0.000, P = 0.002).

CONCLUSION: S100A2 and p63 protein both play important roles in the carcinogenesis of ESCC. An investigation into the combined expression of S100A2 and p63 may be helpful in early diagnosis and in evaluating the prognosis of ESCC.

Immunogenicity of HLA-A1-restricted peptides derived from S100A4 (metastasin 1) in melanoma patients

S100A4 (metastasin 1) belongs to the S100 family of Ca(2+) binding proteins. While not present in most differentiated adult tissues, S100A4 is upregulated in the micromilieu of tumors. It is primarily expressed by tumor-associated macrophages, fibroblasts, and tumor endothelial cells. Due to its strong induction in tumors S100A4 is a promising target for cancer immunotherapy. By reverse immunology, using epitope prediction programs, we identified 3 HLA-A1-restricted peptide epitopes (S100A4 A1-1, A1-2, and A1-3) which are subject to human T cell responses as detected in peripheral blood of melanoma patients by means of IFN-gamma ELISPOT and cytotoxicity assays. In addition, IFN-gamma responses to S100A4 A1-2 can not only be induced by stimulation of T cells with peptide-loaded DC but also by stimulation with S100A4 protein-loaded DC, indicating that this epitope is indeed generated by processing of the endogenously expressed protein. In addition, S100A4 A1-2 reactive T cells demonstrate lysis of HLA-A1(+) fibroblasts in comparison to HLA-A1(-) fibroblasts. In summary, this HLA-A1-restricted peptide epitope is a candidate for immunotherapeutical approaches targeting S100A4-expressing cells in the tumor stroma.

Subepithelial myofibroblast in lung adenocarcinoma: a histological indicator of excellent prognosis

We report here the presence of subepithelial myofibroblasts in pure bronchioloalveolar carcinoma and a subset of invasive lung adenocarcinoma. The subepithelial myofibroblasts we describe were observed in a peculiar location beneath the cancer cells in the alveolar septa. Immunohistochemically, they were positive for alpha-smooth muscle actin and calponin, but negative for desmin and h-caldesmon. To gain insight into their biological significance, we examined 116 surgically resected lung adenocarcinomas. The resected tumors included 13 bronchioloalveolar carcinomas, 20 mixed type adenocarcinomas with bronchioloalveolar carcinoma components, 57 papillary adenocarcinomas, 22 solid adenocarcinomas with mucin, and 4 acinar adenocarcinomas. All specimens were immunostained for alpha-smooth muscle actin to visualize the myofibroblasts. In all of the pure bronchioloalveolar carcinomas observed, the subepithelial myofibroblasts were completely preserved adjacent to the cancer cells. In mixed adenocarcinomas with bronchioloalveolar carcinoma components, subepithelial myofibroblasts were present in the bronchioloalveolar carcinoma components, but scanty in the invasive areas, where stromal myofibroblasts emerged between the cancer cell nests. Subepithelial myofibroblasts were retained, however, in the invasive areas of a subset of invasive adenocarcinomas. Survival analysis showed that the retention of subepithelial myofibroblasts in these invasive tumors was associated with low rates of lymphatic and vascular invasion, a low rate of lymph node involvement, and an excellent patient survival. These results suggest that subepithelial myofibroblasts increase in bronchioloalveolar carcinomas, but are gradually replaced by typical stromal myofibroblasts during progression into invasive cancer. A subset of invasive adenocarcinomas retains subepithelial myofibroblasts. Analysis of subepithelial myofibroblasts may be helpful in identifying a subset of lung adenocarcinoma with excellent prognosis.

The expression of COX-2, hTERT, MDM2, LATS2 and S100A2 in different types of non-small cell lung cancer (NSCLC)

Several studies have reported different expression levels of certain genes in NSCLC, mostly related to the stage and advancement of the tumours. We investigated 65 stage I-III NSCLC tumours: 32 adenocarcinomas (ADC), 26 squamous cell carcinomas (SCC) and 7 large cell carcinomas (LCC). Using the real-time reverse transcription polymerase chain reaction (RT-PCR), we analysed the expression of the COX-2, hTERT, MDM2, LATS2 and S100A2 genes and researched the relationships between the NSCLC types and the differences in expression levels. The differences in the expression levels of the LATS2, S100A2 and hTERT genes in different types of NSCLC are significant. hTERT and COX-2 were over-expressed and LATS2 under-expressed in all NSCLC. We also detected significant relative differences in the expression of LATS2 and MDM2, hTERT and MDM2 in different types of NSCLC. There was a significant difference in the average expression levels in S100A2 for ADC and SCC. Our study shows differences in the expression patterns within the NSCLC group, which may mimic the expression of the individual NSCLC type, and also new relationships in the expression levels for different NSCLC types.

Binding of S100 proteins to RAGE: an update

The Receptor for Advanced Glycation Endproducts (RAGE) is a multi-ligand receptor of the immunoglobulin family. RAGE interacts with structurally different ligands probably through the oligomerization of the receptor on the cell surface. However, the exact mechanism is unknown. Among RAGE ligands are members of the S100 protein family. S100 proteins are small calcium binding proteins with high structural homology. Several members of the family have been shown to interact with RAGE in vitro or in cell-based assays. Interestingly, many RAGE ligands appear to interact with distinct domains of the extracellular portion of RAGE and to trigger various cellular effects. In this review, we summarize the modes of S100 protein-RAGE interaction with regard to their cellular functions.

Metastasis promoter S100A4 is a potentially valuable molecular target for cancer therapy

The growth, invasion and metastatic spread of cancer have been identified with the deregulation of cell proliferation, altered intercellular and cell-substratum adhesion and enhanced motility and the deposition of disseminated cancer cells at distant sites. The identification of therapeutic targets for cancer is crucial to human welfare. Drug development, molecular modelling and design of effective drugs greatly depend upon the identification of suitable therapeutic targets. Several genetic determinants relating to proliferation and growth, invasion and metastasis have been identified. S100A4 appears to be able to activate and integrate pathways to generate the phenotypic responses that are characteristic of cancer. S100A4 signalling can focus on factors associated with normal and aberrant proliferation, apoptosis and growth, and differentiation. It is able to activate signalling pathways leading to the remodelling of the cell membrane and the extracellular matrix; modulation of cytoskeletal dynamics, acquisition of invasiveness and induction of angiogenesis. Therefore S100A4 is arguably a molecular target of considerable potential possessing a wide ranging biological activity that can alter and regulate the major phenotypic features of cancer. The evolution of an appropriate strategy that permits the identification of therapeutic targets most likely to be effective in the disease process without unduly affecting normal biological processes and function is an incontrovertible imperative. By virtue of its ability to activate interacting and multi-functional signalling systems, S100A4 appears to offer suitable targets for developing new therapeutic procedures. Some effectors of the S100A4-activated pathways might also lend themselves as foci of therapeutic interest.

The basic C-terminal amino acids of calcium-binding protein S100A4 promote metastasis

The calcium-binding protein S100A4 can induce a metastatic phenotype in animal model systems and its expression in various human cancers has been shown to be associated with metastasis and reduced patient survival. Using a series of nested deletion mutants, it is now shown that the two C-terminal lysine residues are required for the enhanced metastasis, invasion and migration abilities that S100A4 confers on cells in a model system of metastasis. Basic C-terminal residues enhance the affinity between S100A4 and its best characterized target, a recombinant C-terminal fragment of non-muscle myosin II heavy chain isoform A (NMMHC-IIA). In wild-type S100A4 protein, the presence of the C-terminal lysine, residue 101, enhances the rate of association between S100A4 and NMMHC-IIA. These results identify the amino acids of S100A4 that are involved in metastasis induction and show that the C-terminal region of S100A4 is a possible target for inhibitors of its metastatic action.

Frequent polymorphic variations but rare tumour specific mutations of the S100A2 on 1q21 in non-small cell lung cancer

Contrary to the recent hypothesis that S100A2 is a tumour suppressor, no somatic mutations have yet been identified. We therefore screened 90 non-small cell lung carcinoma (NSCLC) samples, initially for mutations in S100A2 and then also for mutations in P53 and K-RAS genes. Alterations were detected in 46.7% of squamous lung cancer (SCC) samples, but we detected only one novel tumour specific mutation, Q23X in squamous carcinoma. We detected four polymorphisms, two of them published for the first time (144+109 C/G and 297+75A/G) and two already published: S62N, in the coding region and related to squamous cell carcinoma (SCC), and 297+17T/C. Analysis of S100A2 expression revealed that expression in adenocarcinomas and squamous cell carcinomas is significantly different, but not related to any of the found alterations. In one tumour with S62N polymorphism, P53 and K-RAS genes were also mutated, while two tumours with the Q23X mutation have a P53 but no K-RAS mutation. To the best of our knowledge, this is the first report describing alterations in the S100A2 gene proving a relation between changes in predominantly squamous lung cancer.

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

BACKGROUND

In a previously published in vitro study based on top-down proteomics we found that the calcium-binding proteins S100A6 and S100A4 were affected by exposure to ionizing radiation in a p53-dependent fashion. Both proteins showed post-translational modification changes, and S100A6 also showed increased expression and translocation in response to irradiation. Aim of the present study was to evaluate the expression of S100A6 and S100A4 in non-small-cell lung cancer (NSCLC).

METHODS

S100A6 expression on archival tumor cell lysates from 39 patients with radically resected NSCLC was assessed with SELDI-TOF-MS. S100A6 identity was confirmed using a SELDI-based antibody-capture method on lysates from the A549 lung cancer cell line, cell lysates from two freshly prepared NSCLC samples, four plasma samples and one pleural effusion sample. Immunostainings for S100A6, S100A4 and p53 were performed on tissue microarrays containing 103 stage I surgically resected NSCLC cases and 14 normal lung parenchyma specimens.

RESULTS

The presence of post-translationally modified S100A6 forms was confirmed with SELDI-MS on enriched tumor cell lysates, as well as in plasma and pleural effusion samples. In addition, high S100A6 peak intensity was associated with longer median survival (35 months vs. 18 months for high and low peak intensity, respectively; p=n.s.). The immunohistochemical analysis showed that 25% of tumors were S100A6 positive. S100A6 expression correlated directly with non-squamous histology (p<0.0001) and S100A4 expression (p=0.005), and inversely with p53 expression (p=0.01). S100A6-positive cases showed a trend of longer survival compared with S100A6-negative cases (p=0.07). This difference became significant when the analysis was restricted to p53-negative cases (n=72). In this subgroup of patients, whose tumors likely exhibit a functional p53, S100A6 was an independent prognostic factor of improved survival at multivariate analysis (HR 0.49, 95% CI 0.27-0.81, p=0.017).

CONCLUSIONS

In this study we have validated on clinical material our previous findings on cell lines in terms of S100A6 expression and post-translational modifications pattern in NSCLC. Moreover, the survival results obtained in p53-negative stage I NSCLC cases support the proposed pro-apoptotic function of S100A6 and suggest the hypothesis of a cross regulation between these two proteins.