S100A2-S100P expression profile and diagnosis of non-small cell lung carcinoma: impairment by advanced tumour stages and neoadjuvant chemotherapy

An Extracellular/Membrane-Bound S100P Pool Regulates Motility and Invasion of Human Extravillous Trophoblast Lines and Primary Cells

Whilst S100P has been shown to be a marker for carcinogenesis, we have shown, in non-physio-pathological states, that its expression promotes trophoblast motility and invasion but the mechanisms explaining these cellular processes are unknown. Here we identify the presence of S100P in the plasma membrane/cell surface of all trophoblast cells tested, whether lines, primary extravillous (EVT) cells, or section tissue samples using either biochemical purification of plasma membrane material, cell surface protein isolation through biotinylation, or microscopy analysis. Using extracellular loss of function studies, through addition of a specific S100P antibody, our work shows that inhibiting the cell surface/membrane-bound or extracellular S100P pools significantly reduces, but importantly only in part, both cell motility and cellular invasion in different trophoblastic cell lines, as well as primary EVTs. Interestingly, this loss in cellular motility/invasion did not result in changes to the overall actin organisation and focal adhesion complexes. These findings shed new light on at least two newly characterized pathways by which S100P promotes trophoblast cellular motility and invasion. One where cellular S100P levels involve the remodelling of focal adhesions whilst another, an extracellular pathway, appears to be focal adhesion independent. Both pathways could lead to the identification of novel targets that may explain why significant numbers of confirmed human pregnancies suffer complications through poor placental implantation.

S100P Interacts with p53 while Pentamidine Inhibits This Interaction

S100P, a small calcium-binding protein, associates with the p53 protein with micromolar affinity. It has been hypothesized that the oncogenic function of S100P may involve binding-induced inactivation of p53. We used 1H-15N HSQC experiments and molecular modeling to study the molecular interactions between S100P and p53 in the presence and absence of pentamidine. Our experimental analysis indicates that the S100P-53 complex formation is successfully disrupted by pentamidine, since S100P shares the same binding site for p53 and pentamidine. In addition, we showed that pentamidine treatment of ZR-75-1 breast cancer cells resulted in reduced proliferation and increased p53 and p21 protein levels, indicating that pentamidine is an effective antagonist that interferes with the S100P-p53 interaction, leading to re-activation of the p53-21 pathway and inhibition of cancer cell proliferation. Collectively, our findings suggest that blocking the association between S100P and p53 by pentamidine will prevent cancer progression and, therefore, provide a new avenue for cancer therapy by targeting the S100P-p53 interaction.

S100P enhances the motility and invasion of human trophoblast cell lines

S100P has been shown to be a marker for carcinogenesis where its expression in solid tumours correlates with metastasis and a poor patient prognosis. This protein's role in any physiological process is, however, unknown. Here we first show that S100P is expressed both in trophoblasts in vivo as well as in some corresponding cell lines in culture. We demonstrate that S100P is predominantly expressed during the early stage of placental formation with its highest expression levels occurring during the first trimester of gestation, particularly in the invading columns and anchoring villi. Using gain or loss of function studies through overexpression or knockdown of S100P expression respectively, our work shows that S100P stimulates both cell motility and cellular invasion in different trophoblastic and first trimester EVT cell lines. Interestingly, cell invasion was seen to be more dramatically affected than cell migration. Our results suggest that S100P may be acting as an important regulator of trophoblast invasion during placentation. This finding sheds new light on a hitherto uncharacterized molecular mechanism which may, in turn, lead to the identification of novel targets that may explain why significant numbers of confirmed human pregnancies suffer complications through poor placental implantation.

Identification of genes associated with matrix metalloproteinases in invasive lung adenocarcinoma

The aim of the present study was to identify genes with similar function to that of matrix metalloproteinases (MMPs) in invasive lung adenocarcinoma (AC) and to screen the transcription factors that regulate MMPs. The gene expression dataset GSE2514, including 20 invasive lung AC samples and 19 adjacent normal lung samples, was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened using the limma package in R. Genes with similar function to MMPs were identified by K-means clustering. Their correlations with MMPs were validated using Pearson correlation analysis. The expression of MMPs in lung cancer and normal tissues was evaluated by western blot analysis. Protein-protein interaction (PPI) network and transcriptional regulatory network analyses were performed with Retrieval of Interacting Genes and Database for Annotation, Visualization and Integrated Discovery, respectively. As a result, 269 DEGs were identified between invasive lung AC samples and normal lung samples, including 78 upregulated and 191 downregulated genes. Four MMPs (MMP1, MMP7, MMP9 and MMP12), which were upregulated in lung AC, were clustered into one group with other genes, including NAD(P)H quinone oxidoreductase 1, claudin 3 (CLDN3), S100 calcium-binding protein P, serine protease inhibitor Kazal type 1, collagen type XI α 1 chain, periostin and desmoplakin (DSP), following cluster analysis. Pearson correlation analysis further confirmed correlations between MMP9-CLDN3, MMP9-DSP and MMP12-DSP. PPI network analysis also indicated multiple interactions between MMPs-associated genes. Furthermore, MMPs were commonly regulated by CCAAT/enhancer binding protein α transcription factor. These findings may provide further insight into the mechanisms of MMPs in invasive lung AC.

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.

Exhaled breath condensate biomarkers for the early diagnosis of lung cancer using proteomics

We explored whether the proteomic analysis of exhaled breath condensate (EBC) may provide biomarkers for noninvasive screening for the early detection of lung cancer (LC). EBC was collected from 192 individuals [49 control (C), 49 risk factor-smoking (S), 46 chronic obstructive pulmonary disease (COPD) and 48 LC]. With the use of liquid chromatography and tandem mass spectrometry, 348 different proteins with a different pattern among the four groups were identified in EBC samples. Significantly more proteins were identified in the EBC from LC compared with other groups (C: 12.4 ± 1.3; S: 15.3 ± 1; COPD: 14 ± 1.6; LC: 24.2 ± 3.6; P = 0.0001). Furthermore, the average number of proteins identified per sample was significantly higher in LC patients, and receiver operating characteristic curve (ROC) analysis showed an area under the curve of 0.8, indicating diagnostic value. Proteins frequently detected in EBC, such as dermcidin and hornerin, along with others much less frequently detected, such as hemoglobin and histones, were identified. Cytokeratins (KRTs) were the most abundant proteins in EBC samples, and levels of KRT6A, KRT6B, and KRT6C isoforms were significantly higher in samples from LC patients ( P = 0.0031, 0.0011, and 0.0009, respectively). Moreover, the amount of most KRTs in EBC samples from LC patients showed a significant positive correlation with tumor size. Finally, we used a random forest algorithm to generate a robust model using EBC protein data for the diagnosis of patients with LC where the area under the ROC curve obtained indicated a good classification (82%). Thus this study demonstrates that the proteomic analysis of EBC samples is an appropriated approach to develop biomarkers for the diagnosis of lung cancer.

Uncovering Driver DNA Methylation Events in Nonsmoking Early Stage Lung Adenocarcinoma

As smoking rates decrease, proportionally more cases with lung adenocarcinoma occur in never-smokers, while aberrant DNA methylation has been suggested to contribute to the tumorigenesis of lung adenocarcinoma. It is extremely difficult to distinguish which genes play key roles in tumorigenic processes via DNA methylation-mediated gene silencing from a large number of differentially methylated genes. By integrating gene expression and DNA methylation data, a pipeline combined with the differential network analysis is designed to uncover driver methylation genes and responsive modules, which demonstrate distinctive expressions and network topology in tumors with aberrant DNA methylation. Totally, 135 genes are recognized as candidate driver genes in early stage lung adenocarcinoma and top ranked 30 genes are recognized as driver methylation genes. Functional annotation and the differential network analysis indicate the roles of identified driver genes in tumorigenesis, while literature study reveals significant correlations of the top 30 genes with early stage lung adenocarcinoma in never-smokers. The analysis pipeline can also be employed in identification of driver epigenetic events for other cancers characterized by matched gene expression data and DNA methylation data.

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.

Significance of S100P as a biomarker in diagnosis, prognosis and therapy of opisthorchiasis-associated cholangiocarcinoma

Cholangiocarcinoma (CCA) is a malignancy of bile duct with the difficulty in early diagnosis, poor prognosis and less alternation in therapy. S100P is a member of S100 family proteins and plays important roles in cancers. We investigated the S100P expression and its correlation with clinicopathology in 78 cases of opisthorchiasis-associated CCA, and the effects of S100P knockdown with shRNA interference on the proliferation, cell cycle, migration, apoptosis and sensitivity to anti-cancer drug. Extremely high expression of S100P mRNA was detected in the CCA tumor tissues. The increased S100P protein expression was immunohistochemically confirmed and localized in the CCA cytoplasm and/or nuclei as well as in the hyperneoplasia and dysplasia bile ducts, but not in normal bile ducts. The intensity of immunostaining was correlated with survival, tumor stage and metastasis, and the high expression could be an independent prognostic factor. High levels of S100P were detected in the serum and bile fluid of CCA patients. The shRNA-mediated knockdown of S100P expression inhibited the proliferation in vitro and in vivo, and migration of CCA cells, arrested cell cycle with the up-regulated expression of cell cycle arrest related factors, p21, p27, GADD45A, and 14-3-3 zeta. S100P knockdown also promoted CCA cell apoptosis by up-regulating expression of apoptosis related factors, DR5, TRADD, caspase 3 and BAX, and increased the sensitivity of CCA cells to the chemotherapeutic agents sunitinib and apigenin. Taken together, this study indicates that S100P might be a promising biomarker for the diagnosis, prognosis and therapy of CCA.

Keap1-Nrf2 Interaction Suppresses Cell Motility in Lung Adenocarcinomas by Targeting the S100P Protein

PURPOSE

Kelch-like ECH-associated protein 1 (Keap1) is an E3 ligase participated in the cellular defense response against oxidative stress through nuclear factor erythroid-2-related factor 2 (Nrf2). However, the role of Keap1 in regulating cancer motility is still controversial. We investigated the contribution of the Keap1-Nrf2 axis in the progression of non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

The expression of Keap1 and Nrf2 was examined via immunohistochemistry, real-time PCR, and Western blot analysis in a cohort of NSCLC tissues and cells. A series of in vivo and in vitro assays was performed to elucidate the contribution of the Keap1-Nrf2 axis in lung cancer mobility and progression.

RESULTS

Keap1 expression was decreased in specimens from NSCLC patients with lymph node metastasis compared with patients without metastasis. Higher Keap1 expression levels were correlated with the survival of NSCLC patients. Moreover, manipulation of Keap1 expression affected cell migration/invasion abilities. Depletion of Nrf2 relieved the migration promotion imposed by Keap1 suppression. Mechanistic investigations found that S100P was downregulated in both Keap1-overexpressing and Nrf2-knockdown NSCLC cells. Overexpression of Keap1 and knockdown of Nrf2 both suppressed S100P expression in NSCLC cells. Knockdown of S100P inhibited cell migration in highly invasive NSCLC cells and also relieved the migration promotion imposed by Keap1 suppression in weakly invasive NSCLC cells.

CONCLUSIONS

Our findings suggest that Keap1 functions as a suppressor of tumor metastasis by targeting the Nrf2/S100P pathway in NSCLC cells. In addition, overexpression of Keap1 may be a novel NSCLC treatment strategy and/or useful biomarker for predicting NSCLC progression.

In silico analysis of S100 gene expression in gastric cancer

AIM: To explore the feasibility and strategy of in silico identification of human gastric cancer-related S100 genes.

METHODS: By combining series analysis of gene expression, virtual Northern blot and microarray data, the expression levels of S100 family members in normal and malignant stomach tissues were systematically investigated through CGAP and GEO.

RESULTS: At least 5 S100 genes were found to be upregulated in gastric cancer by in silico analysis. Among them, four genes, including S100A2, S100A4, S100A7 and S100A10, were reported to be overexpressed in gastric cancer.

CONCLUSION: To our knowledge this is the first report of systematic evaluation of S100 gene expression in gastric cancer by in silico analysis. The results indicated that overexpression of S100 gene family members is a characteristic of gastric cancer. Reasonable use of public databases by the internet-available tools is a simple, effective approach to identify cancer-related genes, and might provide useful clues to further investigation although the results require experimental validation.

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.

S100A2 protein and non-small cell lung cancer. The dual role concept

S100A2 is a member of the EF-hand motif family S100. Its role has been recently implicated in carcinogenesis and metastasis. Although its precise role in NSCLC patients is debated and conflicting results have been published, it has been associated with patient survival. S100A2 expression was downregulated in some studies while others disagree that S100A2 is strongly expressed in lung cancer. It has been recently published by Hountis et al. that there is a significant association between nuclear S100A2 positivity and better disease-free interval. Intensity of expression was the highest in the early and advanced stages, and equally distributed in the middle stages. This is indicative for a dual role of this protein in carcinogenesis. The expression of S100A2 in operable NSCLC varies widely, and this differential location and expression pattern (nuclear or cytoplasmic or both) seem to correlate with prognosis. The precise role for the movement of S100A2 protein between cytoplasm and nucleus is still unclear. We present here a literature review, and we propose the dual concept on its substantial role as a prognostic or predictive indicator in this unfavorable group of patients.

Overexpression of S100P promotes colorectal cancer metastasis and decreases chemosensitivity to 5-FU in vitro

S100P has been shown to be overexpressed in various cancers and to have putative involvement in the metastatic process. However, Clinical and pathological significance of S100P expression in colorectal cancer still needs to be further studied. In the present study, the method of immunohistochemistry was utilized to investigate S100P protein expression in 91 cases of colorectal cancer. Also, the influence of ectopic expression of S100P on the biologic behavior in SW480 colorectal cancer cells was studied. We found that S100P expression of colorectal cancer tissue was significantly higher than that of normal colorectal mucosal tissues. S100P expression showed to be significantly correlated with clinical staging, lymph node metastasis and recurrence. Ectopic expression of S100P promotes SW480 cancer cells migration and invasion, decreases chemosensitivity to 5-FU in vitro. These findings suggested that S100P could serve as a promising candidate for colorectal cancer marker, prognostic indicator, and therapeutic target.

S100P predicts prognosis and drug resistance in gastric cancer

PURPOSE

S100P has been shown to participate in processes of various human malignancies. In this study, we analyzed the tissue expression of S100P in gastric cancer and evaluated its significance.

METHODS

We determined the S100P expression in 156 gastric cancer patients by quantitative RT-PCR. Tumor characteristics and overall survival (OS) for each patient were examined. In vitro experiments were conducted to examine whether ectopic expression of S100P modifies the proliferation and drug resistance of gastric cancer cells.

RESULTS

Higher expression of S100P occurred in human gastric cancer tissues in comparison with normal controls. Highly expressed S100P in gastric cancer was correlated with TNM stage and prognosis. The 5-year survival rate was significantly lower in patients with high levels of S100P expression than in patients with low levels of expression. Ectopic expression of S100P was associated with an increase in tumor cell proliferation and drug resistance.

CONCLUSION

The expression of S100P in human gastric cancer tissues was upregulated in comparison with normal controls. By establishing an association between S100P expression and shortened OS, increase in proliferation and drug resistance, this study indicates that S100P may be a useful prognostic marker for gastric cancer patients.

S100P expression is a novel prognostic factor in hepatocellular carcinoma and predicts survival in patients with high tumor stage or early recurrent tumors

The calcium-binding protein S100P is expressed in a variety of human cancer cells and is important in cancer cell growth and invasion. Using differential display, we found S100P is overexpressed in human hepatocellular carcinoma (HCC). We examined the expression of 305 unifocal, primary HCC tumors using immunohistochemistry. The S100P protein was expressed in 173 of the 305 (56.7%) HCC tumors. The expression of S100P correlated with female sex (P = 0.0162), high serum α-fetoprotein level (P = 0.0001), high tumor grade (P = 0.0029), high tumor stage (P = 0.0319), the presence of the p53 mutation (P = 0.0032), and the absence of the β-catenin mutation (P = 0.0489). Patients with HCC tumors that expressed S100P were more likely to have early tumor recurrence (ETR) (P = 0.0189) and lower 5-year survival (P = 0.0023). The multivariate analysis confirmed that S100P expression was an independent prognostic factor in HCC. The combinatorial analysis showed an additive unfavorable prognostic interaction between S100P expression and the p53 mutation. In contrast, the β-catenin mutation was associated with better prognosis in both S100P-positive and -negative HCCs. Furthermore, S100P expression was a predictor of survival in HCC patients with high tumor stage or ETR (P = 0.0026 and P = 0.0002, respectively). Our study indicates the expression of the S100P protein is a novel independent predictor for poor prognosis in HCC, and it is also an unfavorable prognostic predictor in HCC patients with high tumor stage or ETR.

A minimally invasive and simple screening test for detection of pancreatic ductal adenocarcinoma using biomarkers in duodenal juice

OBJECTIVES

The aim of this study was to establish a minimally invasive and simple screening test for detection of pancreatic ductal adenocarcinoma (PDAC) using duodenal juice (DJ).

METHODS

Duodenal juice was collected prospectively before endoscopic retrograde cholangiopancreatography in 46 patients. A protease inhibitor was not added to the samples collected during the initial 2.5 minutes but was added in the latter 2.5 minutes. Thereafter, secretin was administered intravenously, and DJ was subsequently collected for additional 10 minutes. The sensitivities of carcinoembryonic antigen (CEA), S100 calcium-binding protein P (S100P), and interleukin 8 in DJ and pancreatic juice were assessed.

RESULTS

There were 30 patients with PDAC and 16 with benign lesions. It was possible to collect an adequate amount of DJ without secretin administration. In the PDAC group, CEA concentrations in DJ were significantly higher than those in the benign group, even without the use of a protease inhibitor. S100P levels in DJ in the PDAC group were significantly higher than those in the benign group in the presence of the protease inhibitor.

CONCLUSIONS

Duodenal juice collection during routine upper endoscopy and assessments of CEA and S100P in DJ might become a useful screening test for detection of PDAC.

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.

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.

Immunohistochemical expression of Annexin A2 and S100A proteins in patients with bulky stage IB-IIA cervical cancer treated with neoadjuvant chemotherapy

OBJECTIVE

Abnormal expression of Annexin A2 and S100A proteins has been reported to induce sensitivity/resistance to chemotherapy in a variety of cancers. The aim of this study was to evaluate the significance of Annexin A2 and S100A protein expression to predict response to neoadjuvant chemotherapy and prognostic significance of these protein expressions in bulky stage IB-IIA cervical cancer patients.

METHODS

Paired tumor samples (pre- and post-chemotherapy) were obtained from 68 patients who were treated with cisplatin-based neoadjuvant chemotherapy and radical hysterectomy at our hospital from 2006 to 2011. The expression of Annexin A2 and S100A proteins was analyzed by immunohistochemistry.

RESULTS

Thirty-six patients were identified as chemotherapy-response and 32 were non-response. (a). Protein expression in tumor cells: (1). Exposure of tumor cells to chemotherapy results in a change of Annexin A2 and S100A expression (P<0.05). (2). Annexin A2, S100A8 and S100A9 protein expression correlates with tumor response to chemotherapy (P<0.05). (b). Protein expression in stromal cells: (1). Expression of Annexin A2, S100A8 and S100A9 was increased, but S100A2 and S100A4 was decreased after exposure to chemotherapy (P<0.05). (2). Only S100A4 expression was associated with response to chemotherapy (P<0.05). Multivariate analysis revealed that tumor size (P=0.022), differentiation (P=0.000), Annexin A2 expression in stromal cells (P=0.009), and S100A8 expression in tumor cells (P=0.008) were independent prognostic factors for progression-free survival of cervical cancer patients.

CONCLUSIONS

Expression of some of the measured proteins in tumor and stromal cells correlates with chemotherapy exposure, response to therapy, and progression-free survival.

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.

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.

Targeting S100P inhibits colon cancer growth and metastasis by Lentivirus-mediated RNA interference and proteomic analysis

S100P was recently found to be overexpressed in a variety of cancers and is considered a potential target for cancer therapy, but the functional role or mechanism of action of S100P in colon cancer is not fully understood. In the present study, we knocked down the gene expression of S100P in colon cancer cells using lentivirus-mediated RNA interference. This step resulted in significant inhibition of cancer cell growth, migration and invasion in vitro and tumor growth and liver metastasis in vivo. Moreover, S100P downstream target proteins were identified by proteomic analysis in colon cancer DLD-1 cells with deletion of S100P. Knockdown of S100P led to downregulation of thioredoxin 1 and β-tubulin and upregulation of Rho guanosine diphosphate (GDP) dissociation inhibitor α (RhoGDIA), all potential therapeutic targets in cancer. Taken together, these findings suggest that S100P plays an important role in colon tumorigenesis and metastasis, and the comprehensive and comparative analyses of proteins associated with S100P could contribute to understanding the downstream signal cascade of S100P, leading to tumorigenesis and metastasis.

Methylation markers for small cell lung cancer in peripheral blood leukocyte DNA

INTRODUCTION

Small cell lung cancer (SCLC) is the most aggressive form of lung malignancy.

METHODS

To identify and validate potential DNA methylation markers for risk assessment and disease detection, we examined peripheral blood leukocyte DNA specimens for methylation differences between SCLC cases and controls. We tested 1505 CpG sites using the Illumina Beadchip assay and validated 9 CpG sites using pyrosequencing technology.

RESULTS

In 44 matched SCLC case-control pairs, we identified significant differences at 62 CpG sites (false discovery rate < or =0.05) in 52 independent genes. Of those, we further determined 43 sites in 36 genes with a mean methylation level difference greater than 0.03 between the cases and controls. We then selected and validated 9 CpG sites for methylation differences in an independent set of 138 matched case-control pairs. The 9 validated CpG sites predicted a higher risk for cases than controls in 85.8% of all pairs of cases and controls, and 2 (in genes CSF3R and ERCC1) jointly contributed most of the discriminating ability.

CONCLUSIONS

Our replicated results demonstrated feasibility of applying large-scale methylation arrays for biomarker discovery and subsequent validation in peripheral blood DNA. The CpG sites identified in this study may potentially assist in risk prediction and diagnosis of SCLC.

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.

S100P: a novel therapeutic target for cancer

S100P expression is described in many different cancers, and its expression is associated with drug resistance, metastasis, and poor clinical outcome. S100P is member of the S100 family of small calcium-binding proteins that have been reported to have either intracellular or extracellular functions, or both. Extracellular S100P can bind with the receptor for advanced glycation end products (RAGE) and activate cellular signaling. Through RAGE, S100P has been shown to mediate tumor growth, drug resistance, and metastasis. S100P is specifically expressed in cancer cells in the adult. Therefore, S100P is a useful marker for differentiating cancer cells from normal cells, and can aid in the diagnosis of cancer by cytological examination. The expression of S100P in cancer cells has been related to hypomethylation of the gene. Multiple studies have confirmed the beneficial effects of blocking S100P/RAGE in cancer cells, and different blockers are being developed including small molecules and antagonist peptides. This review summarizes the role and significance of S100P in different cancers.

Identification of hypermethylated genes associated with cisplatin resistance in human cancers

Cisplatin is among the most widely used cytotoxic anticancer agents in solid tumors; however, the development of secondary resistance remains a major obstacle to clinical efficacy. Treatment-related DNA hypermethylation may play a role in creating drug-resistant phenotypes by inactivating genes that are required for cytotoxicity. We applied a pharmacologic unmasking approach to detect hypermethylated genes whose inactivation contributes to cisplatin resistance. Using three pairs of isogeneic, cisplatin-sensitive, and cisplatin-resistant cell lines derived from two parental cell lines (KB-3-1 and SCC25), we identified several hundred genes that were downregulated in each resistant cell line and reactivated by the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine. Among them, 30 genes were common to two or more cell lines and/or reported to be downregulated in previous studies. Bisulfite sequencing confirmed that 14 genes were hypermethylated in resistant cell lines but not in the sensitive parental cell lines. Six of 14 genes (SAT, C8orf4, LAMB3, TUBB, G0S2, and MCAM) were cisplatin inducible in sensitive but not in resistant cell lines. Small interfering RNA knockdown of two genes, SAT and S100P, increased cell viability with cisplatin treatment in sensitive parental cell lines. S100P knockdown significantly decreased the S-phase fraction of parental sensitive cell lines and slowed cell proliferation, which was associated with decreased sensitivity to cisplatin. Based on these findings, we conclude that DNA methylation is a frequent event in cells that are chronically exposed to cisplatin and that methylation-induced gene silencing may play a role in the development of resistance to cytotoxic chemotherapeutic agents.

Comparison of lung cancer cell lines representing four histopathological subtypes with gene expression profiling using quantitative real-time PCR

BACKGROUND

Lung cancers are the most common type of human malignancy and are intractable. Lung cancers are generally classified into four histopathological subtypes: adenocarcinoma (AD), squamous cell carcinoma (SQ), large cell carcinoma (LC), and small cell carcinoma (SC). Molecular biological characterization of these subtypes has been performed mainly using DNA microarrays. In this study, we compared the gene expression profiles of these four subtypes using twelve human lung cancer cell lines and the more reliable quantitative real-time PCR (qPCR).

RESULTS

We selected 100 genes from public DNA microarray data and examined them by DNA microarray analysis in eight test cell lines (A549, ABC-1, EBC-1, LK-2, LU65, LU99, STC 1, RERF-LC-MA) and a normal control lung cell line (MRC-9). From this, we extracted 19 candidate genes. We quantified the expression of the 19 genes and a housekeeping gene, GAPDH, with qPCR, using the same eight cell lines plus four additional validation lung cancer cell lines (RERF-LC-MS, LC-1/sq, 86-2, and MS-1-L). Finally, we characterized the four subtypes of lung cancer cell lines using principal component analysis (PCA) of gene expression profiling for 12 of the 19 genes (AMY2A, CDH1, FOXG1, IGSF3, ISL1, MALL, PLAU, RAB25, S100P, SLCO4A1, STMN1, and TGM2). The combined PCA and gene pathway analyses suggested that these genes were related to cell adhesion, growth, and invasion. S100P in AD cells and CDH1 in AD and SQ cells were identified as candidate markers of these lung cancer subtypes based on their upregulation and the results of PCA analysis. Immunohistochemistry for S100P and RAB25 was closely correlated to gene expression.

CONCLUSIONS

These results show that the four subtypes, represented by 12 lung cancer cell lines, were well characterized using qPCR and PCA for the 12 genes examined. Certain genes, in particular S100P and CDH1, may be especially important for distinguishing the different subtypes. Our results confirm that qPCR and PCA analysis provide a useful tool for characterizing cancer cell subtypes, and we discuss the possible clinical applications of this approach.

Combination PPARgamma and RXR Agonist Treatment in Melanoma Cells: Functional Importance of S100A2

Nuclear hormone receptors, including RXR and PPARgamma, represent novel therapeutic targets in melanoma. We have previously shown that the DRO subline of the amelanotic melanoma A375 responds to rexinoid and thiazolidinedione (TZD) treatment in vitro and in vivo. We performed microarray analysis of A375(DRO) after TZD and combination rexinoid/TZD treatment in which the calcium binding protein S100A2 had increased expression after rexinoid or TZD treatment and a synergistic increase to combination treatment. Increased S100A2 expression is dependent on an intact PPARgamma receptor, but it is not sufficient to mediate the antiproliferative effects of rexinoid/TZD treatment. Over expression of S100A2 enhanced the effect of rexinoid and TZD treatment while inhibition of S100A2 expression attenuated the response to rexinoid/TZD treatment, suggesting that S100A2 is necessary for optimal response to RXR and PPARgamma activation by respective ligands. In summary, we have identified potential downstream mediators of rexinoid and TZD treatment in a poorly differentiated melanoma and found that alterations in S100A2 expression affect RXR and PPARgamma signaling in A375(DRO) cells. These studies provide insight into potential mechanisms of tumor response or resistance to these novel therapies.

S100A8/A9: a Janus-faced molecule in cancer therapy and tumorgenesis

Correlations exist between the abundance of S100 proteins and disease pathologies. Indeed, this is evidenced by the heterodimeric S100 protein complex S100A8/A9 which has been shown to be involved in inflammatory and neoplastic disorders. However, S100A8/A9 appears as a Janus-faced molecule in this context. On the one hand, it is a powerful apoptotic agent produced by immune cells, making it a very fascinating tool in the battle against cancer. It spears the risk to induce auto-immune response and may serve as a lead compound for cancer-selective therapeutics. In contrast, S100A8/A9 expression in cancer cells has also been associated with tumor development, cancer invasion or metastasis. Clearly, there is a dichotomy and future investigations into the role of S100A8/A9 in cancer biology need to consider both sides of the same coin.

S100A2 induces metastasis in non-small cell lung cancer

PURPOSE

S100 proteins are implicated in metastasis development in several cancers. In this study, we analyzed the prognostic role of mRNA levels of all S100 proteins in early stage non-small cell lung cancer (NSCLC) patients as well as the pathogenetic of S100A2 in the development of metastasis in NSCLC.

EXPERIMENTAL DESIGN

Microarray data from a large NSCLC patient cohort was analyzed for the prognostic role of S100 proteins for survival in surgically resected NSCLC. Metastatic potential of the S100A2 gene was analyzed in vitro and in a lung cancer mouse model in vivo. Overexpression and RNAi approaches were used for analysis of the biological functions of S100A2.

RESULTS

High mRNA expression levels of several S100 proteins and especially S100A2 were associated with poor survival in surgically resected NSCLC patients. Upon stable transfection into NSCLC cell lines, S100A2 did not alter proliferation. However, S100A2 enhanced transwell migration as well as transendothelial migration in vitro. NOD/SCID mice injected s.c. with NSCLC cells overexpressing S100A2 developed significantly more distant metastasis (64%) than mice with control vector transfected tumor cells (17%; P < 0.05). When mice with S100A2 expressing tumors were treated i.v. with shRNA against S100A2, these mice developed significantly fewer lung metastasis than mice treated with control shRNA (P = 0.021).

CONCLUSIONS

These findings identify S100A2 as a strong metastasis inducer in vivo. S100A2 might be a potential biomarker as well as a novel therapeutic target in NSCLC metastasis.

RAGE (Receptor for Advanced Glycation Endproducts), RAGE ligands, and their role in cancer and inflammation

The Receptor for Advanced Glycation Endproducts [RAGE] is an evolutionarily recent member of the immunoglobulin super-family, encoded in the Class III region of the major histocompatability complex. RAGE is highly expressed only in the lung at readily measurable levels but increases quickly at sites of inflammation, largely on inflammatory and epithelial cells. It is found either as a membrane-bound or soluble protein that is markedly upregulated by stress in epithelial cells, thereby regulating their metabolism and enhancing their central barrier functionality. Activation and upregulation of RAGE by its ligands leads to enhanced survival. Perpetual signaling through RAGE-induced survival pathways in the setting of limited nutrients or oxygenation results in enhanced autophagy, diminished apoptosis, and (with ATP depletion) necrosis. This results in chronic inflammation and in many instances is the setting in which epithelial malignancies arise. RAGE and its isoforms sit in a pivotal role, regulating metabolism, inflammation, and epithelial survival in the setting of stress. Understanding the molecular structure and function of it and its ligands in the setting of inflammation is critically important in understanding the role of this receptor in tumor biology.

In silico analysis and verification of S100 gene expression in gastric cancer

Background

The S100 protein family comprises 22 members whose protein sequences encompass at least one EF-hand Ca²⁺ binding motif. They were involved in the regulation of a number of cellular processes such as cell cycle progression and differentiation. However, the expression status of S100 family members in gastric cancer was not known yet.

Methods

Combined with analysis of series analysis of gene expression, virtual Northern blot and microarray data, the expression levels of S100 family members in normal and malignant stomach tissues were systematically investigated. The expression of S100A3 was further evaluated by quantitative RT-PCR.

Results

At least 5 S100 genes were found to be upregulated in gastric cance by in silico analysis. Among them, four genes, including S100A2, S100A4, S100A7 and S100A10, were reported to overexpressed in gastric cancer previously. The expression of S100A3 in eighty patients of gastric cancer was further examined. The results showed that the mean expression levels of S100A3 in gastric cancer tissues were 2.5 times as high as in adjacent non-tumorous tissues. S100A3 expression was correlated with tumor differentiation and TNM (Tumor-Node-Metastasis) stage of gastric cancer, which was relatively highly expressed in poorly differentiated and advanced gastric cancer tissues (P < 0.05).

Conclusion

To our knowledge this is the first report of systematic evaluation of S100 gene expressions in gastric cancers by multiple in silico analysis. The results indicated that overexpression of S100 gene family members were characteristics of gastric cancers and S100A3 might play important roles in differentiation and progression of gastric 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.