Induction of 18A2/mts1 gene expression and its effects on metastasis and cell cycle control

Enrichment of nuclear S100A4 during G2/M in colorectal cancer cells: possible association with cyclin B1 and centrosomes

S100A4 promotes metastasis in several types of cancer, but the involved molecular mechanisms are still incompletely described. The protein is associated with a wide variety of biological functions and it locates to different subcellular compartments, including nuclei, cytoplasm and extracellular space. Nuclear expression of S100A4 has been associated with more advanced disease stage as well as poor outcome in colorectal cancer (CRC). The present study was initiated to investigate the nuclear function of S100A4 and thereby unravel potential biological mechanisms linking nuclear expression to a more aggressive phenotype. CRC cell lines show heterogeneity in nuclear S100A4 expression and preliminary experiments revealed cells in G2/M to have increased nuclear accumulation compared to G1 and S cells, respectively. Synchronization experiments validated nuclear S100A4 expression to be most prominent in the G2/M phase, but manipulating nuclear levels of S100A4 using lentiviral modified cells failed to induce changes in cell cycle distribution and proliferation. Proximity ligation assay did, however, demonstrate proximity between S100A4 and cyclin B1 in vitro, while confocal microscopy showed S100A4 to localize to areas corresponding to centrosomes in mitotic cells prior to chromosome segregation. This might indicate a novel and uncharacterized function of the metastasis-associated protein in CRC cells.

A Calcium Binding Protein, S100A4, Mediates T Cell Dependent Cytotoxicity as a Transformation-Associated Antigen

The nature of the target molecule of TCR gamma delta T cell-mediated lysis remains to be determined. As we previously reported, #067 monoclonal antibody (mAb) recognizes one of the transformation-associated antigens, designated as #067 antigen. This antigen is expressed on the cell surface of rat fibrosarcoma W31 cells, which are established by transformation of fetal fibroblastic WFB cells with H-ras oncogene. It has been suggested that the #067 antigen is a target molecule for TCR gamma delta T cells since #067 mAb inhibited TCR gamma delta T cell-mediated lysis against #067 positive cells. In this study we attempted to identify the protein sequence of the #067 antigen. By using molecular cloning techniques, we demonstrated that a calcium binding protein, S100A4, was possibly one and the same molecule as the #067 antigen. It was shown that the expression of S100A4 was higher in W31 cells than in WFB cells at transcription and protein level. Flow cytometry and immunocytochemical studies showed that #067 antigen partially co-localized with S100A4 on the cell surface as well as the cytoplasm of W31 cells. Moreover, rabbit anti-S100A4 polyclonal antibodies (pAb) inhibited TCR gamma delta T cell-mediated lysis against #067 positive cells. Our results indicated that S100A4 may play a role as a possible target molecule for TCR gamma delta T cell-mediated lysis although how S100A4 is involved in TCR gamma delta T cell-mediated lysis remains to be determined.

Relationships between metastasis-associated protein (MTA) 1 and lymphatic metastasis in tonsil cancer

We evaluated immunohistochemically the expression profiles of metastasis-associated protein (MTA) 1 and their associations with lymph node metastasis in tonsil cancer. Immunohistochemical analysis of 43 tonsillar neoplasm tissues was performed using antibodies raised to MTA1. Depth of tumor invasion, lymph node metastasis, and clinical outcomes were assessed. Clinical N0 patients were divided into two groups: N0a, negative for MTA1; N0b, positive for MTA1. Occult node metastasis was reevaluated according to the revised clinical N staging system taking account of MTA1 expression. The expression rate of MTA1 was 41.9%. There was a significant correlation between the expression of MTA1 and lymph node metastasis (P = 0.034*). MTA1 had a sensitivity of 53.3% and a specificity of 84.6% for identification of cervical metastases. When cN0b patients were considered to be N+, the recalculated rate of occult metastasis fell from 50% to 7.6% (the false-positive rate remained unchanged). MTA1 was found to be a useful molecular marker to predict lymphatic metastasis in tonsil cancer.

Systematic review of immunohistochemical biomarkers to identify prognostic subgroups of patients with pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) carries a dismal prognosis. There is a need to identify prognostic subtypes of PDAC to predict clinical and therapeutic outcomes accurately, and define novel therapeutic targets. The purpose of this review was to provide a systematic summary and review of available data on immunohistochemical (IHC) prognostic and predictive markers in patients with PDAC.

METHODS

Relevant articles in English published between January 1990 and June 2010 were obtained from PubMed searches. Other articles identified from cross-checking references and additional sources were reviewed. The inclusion was limited to studies evaluating IHC markers in a multivariable setting.

RESULTS

Database searches identified 76 independent prognostic and predictive molecular markers implicated in pancreatic tumour growth, apoptosis, angiogenesis, invasion and resistance to chemotherapy. Of these, 11 markers (Ki-67, p27, p53, transforming growth factor β1, Bcl-2, survivin, vascular endothelial growth factor, cyclo-oxygenase 2, CD34, S100A4 and human equilibrative nucleoside transporter 1) provided independent prognostic or predictive information in two or more separate studies.

CONCLUSION

None of the molecular markers described can be recommended for routine clinical use as they were identified in small cohorts and there were inconsistencies between studies. Their prognostic and predictive values need to be validated further in prospective multicentre studies in larger patient populations. A panel of molecular markers may become useful in predicting individual patient outcome and directing novel types of intervention.

S100A4 over-expression underlies lymph node metastasis and poor prognosis in colorectal cancer

AIM: To develop lymph node metastasis (LNM)-associated biomarkers for colorectal cancer (CRC) using quantitative proteome analysis.

METHODS: Differences in protein expression between primary CRC with LNM (LNM CRC) and without LNM (non-LNM CRC) were assessed using methyl esterification stable isotope labeling coupled with 2D liquid chromatography followed by tandem mass spectrometry (2D-LC-MS/MS). The relationship to clinicopathological parameters and prognosis of candidate biomarkers was examined using an independent sample set.

RESULTS: Forty-three proteins were found to be differentially expressed by at least 2.5-fold in two types of CRC. S100A4 was significantly upregulated in LNM CRC compared with non-LNM CRC, which was confirmed by Western blotting, immunohistochemistry and real-time quantitative polymerase chain reaction. Further immunohistochemistry on another 112 CRC cases showed that overexpression of S100A4 frequently existed in LNM CRC compared with non-LNM CRC (P < 0.001). Overexpression of S100A4 was significantly associated with LNM (P < 0.001), advanced TNM stage (P < 0.001), increased 5-year recurrence rate (P < 0.001) and decreased 5-year overall survival rate (P < 0.001). Univariate and multivariate analyses indicated that S100A4 expression was an independent prognostic factor for recurrence and survival of CRC patients (P < 0.05).

CONCLUSION: S100A4 might serve as a powerful biomarker for LNM and a prognostic factor in CRC.

Overexpression of S100A4 in human cancer cell lines resistant to methotrexate

Background

Methotrexate is a chemotherapeutic drug that is used in therapy of a wide variety of cancers. The efficiency of treatment with this drug is compromised by the appearance of resistance. Combination treatments of MTX with other drugs that could modulate the expression of genes involved in MTX resistance would be an adequate strategy to prevent the development of this resistance.

Methods

The differential expression pattern between sensitive and MTX-resistant cells was determined by whole human genome microarrays and analyzed with the GeneSpring GX software package. A global comparison of all the studied cell lines was performed in order to find out differentially expressed genes in the majority of the MTX-resistant cells. S100A4 mRNA and protein levels were determined by RT-Real-Time PCR and Western blot, respectively. Functional validations of S100A4 were performed either by transfection of an expression vector for S100A4 or a siRNA against S100A4. Transfection of an expression vector encoding for β-catenin was used to inquire for the possible transcriptional regulation of S100A4 through the Wnt pathway.

Results

S100A4 is overexpressed in five out of the seven MTX-resistant cell lines studied. Ectopic overexpression of this gene in HT29 sensitive cells augmented both the intracellular and extracellular S100A4 protein levels and caused desensitization toward MTX. siRNA against S100A4 decreased the levels of this protein and caused a chemosensitization in combined treatments with MTX. β-catenin overexpression experiments support a possible involvement of the Wnt signaling pathway in S100A4 transcriptional regulation in HT29 cells.

Conclusions

S100A4 is overexpressed in many MTX-resistant cells. S100A4 overexpression decreases the sensitivity of HT29 colon cancer human cells to MTX, whereas its knockdown causes chemosensitization toward MTX. Both approaches highlight a role for S100A4 in MTX resistance.

High-level expression of S100A4 correlates with lymph node metastasis and poor prognosis in patients with gastric cancer

BACKGROUND

The present study investigated the clinical significance of S100 calcium binding protein A4 in the development, progression, and metastasis of gastric cancer.

METHODS

Tumor tissue, adjacent normal tissue, and lymph node and peritoneal metastases were obtained from patients with gastric cancer, and their gene expression profiles were analyzed by Affymetrix GeneChip HG-U133A2.0 array. The expression of S100A4 was detected by real-time quantitative reverse-transcription polymerase chain reaction (RT-PCR) in gastric tumor tissue and lymph node and peritoneum metastasis. Immunohistochemistry was employed to analyze S100A4 expression in 436 clinicopathologically characterized gastric cancer cases and in corresponding distant metastases from 61 patients.

RESULTS

A total of 434 genes and 169 expressed sequence tags were upregulated by at least twofold in the tumor tissue. The expression of S100A4 in lymph node and peritoneal metastases was significantly higher than that in gastric tumor tissue. The expression of S100A4 messenger RNA (mRNA) or protein differed significantly among gastric tumor tissue, matched normal gastric mucosa, and lymph node and peritoneal metastases. Further multivariate analysis suggested that depth of invasion, lymph node and distant metastases, tumor-node-metastasis (TNM) stage, and upregulation of S100A4 were independent prognostic indicators for the disease.

CONCLUSION

Gene expression profiles are a useful way to perform simultaneously large-scale analysis of the expression level of thousands of genes. Expression of S100A4 in gastric cancer is associated significantly with lymph node and distant metastases, and poor prognosis. S100A4 may be a useful marker to predict development, progression, and metastasis of gastric cancer.

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.

Prognostic significance of S100A4 and vascular endothelial growth factor expression in pancreatic cancer

AIM: To investigate the expression of vascular endothelial growth factor (VEGF) and calcium-binding protein S100A4 in pancreatic cancer and their relationship to the clinicopathological parameters and prognosis of pancreatic cancer.

METHODS: Expression status of VEGF and S100A4 was examined in 62 surgical specimens of primary pancreatic cancer by immunohistochemistry. Correlation between the expression of VEGF and S100A4 and clinicopathological parameters was analyzed.

RESULTS: Thirty-eight of 62 (61.3%) specimens of primary pancreatic cancer were positive for S100A4. Thirty-seven (59.7%) specimens showed positive expression of VEGF. The positive correlation between S100A4 and VEGF expression was significant in cancer tissues (P < 0.001). S100A4 expression was significantly correlated with tumor size, TNM stage and poorer prognosis. VEGF expression had a significant correlation with poorer prognosis. The prognosis of 17 S100A4- and VEGF-negative cancer patients was significantly better than that of other patients (P < 0.05). Distant metastasis (P = 0.001), S100A4- (P = 0.008) and VEGF-positive expression (P = 0.016) were significantly independent prognostic predictors (P < 0.05).

CONCLUSION: Over-expression of S100A4 and VEGF plays an important role in the development of pancreatic cancer. Combined examination of the two molecules might be useful in evaluating the outcome of patients with pancreatic cancer.

Metastasis-associated protein S100A4 and p53 predict relapse in curatively resected stage III and IV (M0) gastric cancer

PURPOSE

Pathologic stage is the most important predictive factor of relapse in gastric cancer after curative resection. However, patients with the same stage often have different risks of relapse. Here, we investigated whether the expressions of molecular markers can supplement the current staging system in terms of relapse prediction.

PATIENTS AND METHODS

One hundred and nine stage III or IV (M0) patients who had received curative gastrectomy followed by adjuvant 5-fluorouracil and cisplatin chemotherapy were included in this study. The expressions of molecular markers including p53, p27, COX-2, HER-2, EGFR, maspin, S100A4, E-cadherin, Sp1, and p97 were analyzed by immunohistochemistry in cancer and paired normal tissues.

RESULTS

The overall relapse rate was 58.7%, and pathologic stage was a significant predictive factor of relapse (42% in stage IIIA, 48% in IIIB, 76% in IV, p = 0.005). Of the 10 markers examined, p53 and S100A4 were expressed only in tumor tissues, and S100A4 expression was significantly associated with a higher relapse rate (85% vs. 53%, p = 0.008). In multivariate analysis including tumor stage, S100A4 and p53 expression were independent predictive factors of relapse (relative risk, 6.98; 95% confidence interval [CI], 1.608-30.342, 3.49; 95% CI, 1.328-9.186, respectively). On comparing patients who expressed S100A4 or p53 with those who expressed neither, relapse rates were 58% vs. 25% in stage III (p = 0.011) and 95% vs. 59% in stage IV (M0) (p = 0.003).

CONCLUSION

In addition to staging system, the expressions of S100A4 and p53 were significant predictive factors of relapse in gastric cancer after curative resection and adjuvant chemotherapy.

Hyperthermia inhibits cell proliferation and induces apoptosis: relative signaling status of P53, S100A4, and Notch in heat sensitive and resistant cell lines

The effects of hyperthermia on the expression of p53, the apoptosis-associated genes Bax and Bcl-2, Notch and S100A4 have been studied in the HepG2 cell line and the HUT cell line derived from HepG2, adapted for growth in hyperthermic conditions. Hyperthermia inhibits cell proliferation and induces apoptosis. HepG2 and HUT cells differed in respect of anchorage to growth surface, degree of proliferation and apoptosis and expression of p53, Bax, Bcl-2, Notch, and S100A4 genes. The induction of apoptosis and the inhibition of cell proliferation occurred independently of p53, and independently also of involvement of the apoptosis family genes Bax and Bcl-2. We demonstrate novel and marked differences between transient heat shock and heat adaptation in respect of pathways of signaling and generation of phenotypic effects in vitro. Different signaling patterns have been identified here. Pathways of signaling by S100A4, by its interaction with and sequestration of p53, and by Notch also seem differentially operational in the induction of apoptosis, and both appear to be activated as alternative pathways in the context of hyperthermia signaling independently of p53.

Photochemically Induced Gene Silencing Using Small Interfering RNA Molecules in Combination with Lipid Carriers

Novel strategies for efficient delivery of small interfering RNA (siRNA) molecules with a potential for targeting are required for development of RNA interference (RNAi) therapeutics. Here, we present a strategy that is based on delivery of siRNA molecules through the endocytic pathway, in order to develop a method for site-specific gene silencing. To achieve this, we combined the use of cationic lipids and photochemical internalization (PCI). Using the human S100A4 gene as a model system, we obtained potent gene silencing in four tested human cancer cell lines following PCI induction when using the cationic lipid jetSI-ENDO. Gene silencing was shown at both the RNA and protein levels, with no observed PCI toxicity when using the jetSI reagent and an optimized PCI protocol. This novel induction method opens for in vivo site-specific delivery of siRNA molecules toward a sequence of interest.

Nuclear expression of S100A4 is associated with aggressive behavior of epithelial ovarian carcinoma: an important autocrine/paracrine factor in tumor progression

Although S100A4 expression has reportedly been associated with metastasis of various malignancies, little is known about its biological significance in ovarian carcinomas. In this study, we investigated expression and secretion of S100A4 and its extracellular function in ovarian carcinoma cells. We first used immunohistochemistry to examine the expression and localization of S100A4 in 113 epithelial ovarian neoplasms (24 benign, 20 borderline, and 69 malignant tumors) and analyzed its prognostic significance in patients with ovarian carcinoma. Then we investigated the expression, subcellular localization, and secretion of S100A4 in four ovarian carcinoma cell lines. Finally, we examined the effect of S100A4 treatment on the cell proliferation and invasiveness of ovarian carcinoma cells, along with activation of small GTPase, RhoA. Both cytoplasmic and nuclear expressions of S100A4 were significantly stronger in carcinomas than those in benign and borderline tumors. Ovarian carcinoma patients with strong nuclear S100A4 expression showed a significantly shorter survival than those without (P = 0.0045). This was not the case for cytoplasmic S100A4 expression. Ovarian carcinoma cell lines were shown to express S100A4, and secrete S100A4 into the culture media. Treatment with recombinant S100A4 resulted in the upregulation of S100A4 expression, translocation of S100A4 into the nucleus, and enhancement of invasiveness, which was associated with the upregulation of small GTPase, RhoA. These findings suggest that the nuclear expression of S100A4 is involved in the aggressive behavior of ovarian carcinoma and S100A4 is an autocrine/paracrine factor that plays an important role in the aggressiveness of ovarian carcinoma cells.

Tumor-Associated Antigen Preferentially Expressed Antigen of Melanoma (PRAME) Induces Caspase-Independent Cell Death In vitro and Reduces Tumorigenicity In vivo

Preferentially expressed antigen of melanoma (PRAME) is expressed in a wide variety of tumors, but in contrast with most other tumor associated antigens, it is also expressed in leukemias. The physiologic role of PRAME remains elusive. Interestingly, PRAME expression is correlated with a favorable prognosis in childhood acute leukemias. Moreover, a high expression of PRAME seems to be predominantly found in acute leukemias carrying a favorable prognosis. On these clinical observations, we assumed that PRAME could be involved in the regulation of cell death or cell cycle. In this study, we show that transient overexpression of PRAME induces a caspase-independent cell death in cultured cell lines (CHO-K1 and HeLa). Cells stably transfected with PRAME also exhibit a decreased proliferation rate due, at least partially, to an elevated basal rate of cell death. Immunocytochemistry of a FLAG-tagged PRAME, in vivo imaging of an enhanced green fluorescent protein-tagged PRAME, and Western blotting after cell fractionation reveal a nuclear localization of the protein. Using a microarray-based approach, we show that KG-1 leukemic cells stably transfected with PRAME present a significant decrease of expression of the heat-shock protein Hsp27, the cyclin-dependent kinase inhibitor p21, and the calcium-binding protein S100A4. The expression of these three proteins is known to inhibit apoptosis and has been associated with an unfavorable prognosis in a series of cancers. Finally, repression of PRAME expression by a short interfering RNA strategy increases tumorigenicity of K562 leukemic cells in nude mice. We suggest that all these observations might explain the favorable prognosis of the leukemias expressing high levels of PRAME.

Characterization of fibroblast-specific protein 1 in pulmonary fibrosis

Because fibroblasts produce collagen and other extracellular matrix components that are deposited during tissue fibrosis, defining the behavior of these cells is critical to understanding the pathogenesis of fibrotic diseases. We investigated the utility of fibroblast-specific protein 1 (FSP1), a member of the calmodulin S100 troponin C superfamily, for identifying lung fibroblasts in a murine model of pulmonary fibrosis induced by intratracheal administration of bleomycin. Protein and mRNA expression of FSP1 was minimal in untreated lungs, but increased by 1 week after bleomycin administration and remained increased at 2 and 3 weeks after treatment. By immunohistochemistry, the number of FSP1(+) cells increased in a dose-dependent manner in the lungs after bleomycin treatment. Colocalization of alpha1 procollagen and FSP1 in interstitial cells demonstrated that FSP1(+) fibroblasts contribute to the deposition of collagen after bleomycin administration. In primary lung cell cultures, lung fibroblasts, but not macrophages or type II alveolar epithelial cells, expressed FSP1. FSP1 also identified fibroblasts in lung biopsy specimens from patients with documented usual interstitial pneumonitis. Therefore, FSP1 is an improved marker for lung fibroblasts that could be useful for investigating the pathogenesis of pulmonary fibrosis.

Differential expression of S100 gene family in human esophageal squamous cell carcinoma

PURPOSE

To study the differential expression of the S100 gene family at the RNA level in human esophageal squamous cell carcinoma (ESCC), and to find the relationship of the S100 gene family with ESCC.

METHODS

Firstly, the specific primers were designed for the different S100 genes with Software Primer 3, which required that both primer sequences of each S100 gene were from two different exons respectively. Then, the differential expression of 16 S100 genes was examined by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) in 62 cases of ESCC versus the corresponding normal esophageal mucosa. All RT-PCR products were analyzed by 1.5% agarose gel. With Fluor-S MultiImager and Multi-Analyst software, the electrophoresis images were evaluated with statistics analysis using SAS 8.1 software.

RESULTS

Eleven out of 16 S100 genes were significantly downregulated ( p<0.05) in ESCC versus the normal counterparts such as S100A1, S100A2, S100A4, S100A8, S100A9, S100A10, S100A11, S100A12, S100A14, S100B, and S100P genes. Only the S100A7 gene in the S100 family was markedly upregulated ( p<0.05). Moreover, the S100B gene was significantly correlated with histological differentiation of ESCC ( p=0.0247), and the deregulation of some S100 genes was closely correlated ( p<0.05), such as S100A10/S100A11, S100A2/S100A8, S100A2/S100A14, S100A8/S100A14, and S100A2/S100P etc.

CONCLUSIONS

The S100 gene family is closely associated with ESCC.

Correlation of S100A4 expression with invasion and metastasis in oral squamous cell carcinoma

S100A4 is known to be involved in cancer cell motility by virtue of its ability to activate non-muscle myosin. In the current study, we investigated the interrelationship of clinico-pathological findings and S100A4 expression in oral squamous cell carcinoma (SCC). The expression of S100A4 was examined immunohistochemically in 41 clinical specimens of oral SCC. S100A4 expression was detected in 11 (26.8%) of 41 cases. Although the expression of S100A4 was not associated with the primary tumor site and degree of differentiation, there was a significant correlation between the increased S100A4-expression and the mode of invasion (p < 0.0001). In addition, the S100A4 status showed a clear correlation with lymph node metastasis (P < 0.01). These results lead us to conclude that S100A4 expression status may be a useful prognostic factor in patients with invasive and metastatic oral SCCs.

Prediction of nodal spread of breast cancer by using artificial neural network-based analyses of S100A4, nm23 and steroid receptor expression

The expression of tumour promoter gene S100A4, metastasis suppressor gene nm23, oestrogen and progesterone receptors, and tumour grade and size have been investigated for their potential to predict breast cancer progression. The molecular and cellular data have been analysed using artificial neural networks to determine the potential of these markers to predict the presence of metastatic tumour in the regional lymph nodes. This study shows that tumour grade and size are poor predictors. The relative expression of S100A4 and nm23 genes is the single most effective predictor of nodal status. Inclusion of oestrogen- and progesterone-receptor status with tumour grade and size markers improves prediction; however, there may be some overlap between steroid receptors and molecular markers. This study also underscores the power of artificial neural network techniques to predict the potential of primary breast cancers to spread to axillary lymph nodes. This could aid the clinician in determining whether invasive procedures of axially node dissection can be obviated and whether conservative forms of treatment might be appropriate in the management of the patient.

CCN3 and calcium signaling

The CCN family of genes consists presently of six members in human (CCN1-6) also known as Cyr61 (Cystein rich 61), CTGF (Connective Tissue Growth Factor), NOV (Nephroblastoma Overexpressed gene), WISP-1, 2 and 3 (Wnt-1 Induced Secreted Proteins). Results obtained over the past decade have indicated that CCN proteins are matricellular proteins, which are involved in the regulation of various cellular functions, such as proliferation, differentiation, survival, adhesion and migration. The CCN proteins have recently emerged as regulatory factors involved in both internal and external cell signaling. CCN3 was reported to physically interact with fibulin-1C, integrins, Notch and S100A4. Considering that, the conformation and biological activity of these proteins are dependent upon calcium binding, we hypothesized that CCN3 might be involved in signaling pathways mediated by calcium ions.

In this article, we review the data showing that CCN3 regulates the levels of intracellular calcium and discuss potential models that may account for the biological effects of CCN3.

Nuclear localization of the metastasis-related protein S100A4 correlates with tumour stage in colorectal cancer

A large number of experimental studies have linked the S100A4 gene product to the metastatic phenotype of cancer cells and clinical evidence indicates a correlation between S100A4 expression and poor prognosis in several cancer types. The aim of the present study was to analyse the expression of the S100A4 protein in colorectal cancer. Paraffin-embedded samples from 277 colorectal cancer patients were immunostained with anti-S100A4 antibody. Cytoplasmic staining was observed in 178 of 277 samples (64%), whereas, unexpectedly, nuclear expression of S100A4 was found in 88 of 277 of the samples (32%). This novel finding was confirmed by western blot analysis of nuclear fractions isolated from frozen tumour tissue. Statistical analysis revealed a significant correlation between nuclear expression of S100A4 and tumour stage at diagnosis, while there was no such correlation between cytoplasmic staining and tumour stage. The nuclear localization of S100A4 in colorectal cancer and its relationship to tumour stage suggest that this protein may be involved in gene regulatory pathways of relevance to the metastatic phenotype of cancer cells.

Effects of E-cadherin transfection on gene expression of a gallbladder carcinoma cell line: repression of MTS1/S100A4 gene expression

E-cadherin is important in cell-to-cell adhesion and controls cell polarity and tissue morphology. Loss of E-cadherin expression occurs in various human tumors and is the first step in cancer invasion and metastasis. We demonstrate that the exogenous expression of E-cadherin transfected into G-415 GB cells not only increases cell-to-cell adhesion but also reduces in vitro cell proliferation, motility and invasion. Our aim was to determine what genes are most affected by the exogenous expression of E-cadherin in GB cancer cells. We analyzed gene expression pertaining to cell proliferation, motility and invasion. Conventional RT-PCR was performed for these genes; quantitative RT-PCR was carried out on genes exhibiting altered expression. Conventional RT-PCR revealed that E-cadherin transfection suppressed expression of mts1 mRNA and increased that of c-myc and MT1-MMP. In quantitative RT-PCR analysis, levels of c-myc and MT1-MMP mRNA were elevated by to 2.56- and 2.22-fold, respectively, in the E-cadherin transfectant, whereas mts-1 was 7.14-fold suppressed compared to parental cells. These results indicated that expression of mts1 mRNA was most affected by E-cadherin transfection. Immunocytochemical analysis of transfectant and parental cells demonstrated an inverse correlation in E-cadherin and mts1 expression. Immunohistochemical analysis of 37 GB cancer specimens confirmed this observation in vivo. Loss of E-cadherin expression followed by expression of the mts1 gene may be an important event for increasing cell proliferation, motility and invasion activity in the progression of GB cancer.

Methionine aminopeptidase 2 is a new target for the metastasis-associated protein, S100A4

S100A4 is an EF-hand type calcium-binding protein that regulates tumor metastasis and a variety of cellular processes via interaction with different target proteins. Here we report that S100A4 physically interacts with methionine aminopeptidase 2 (MetAP2), the primary target for potent angiogenesis inhibitors, fumagillin and ovalicin. Using a yeast two-hybrid screen, S100A4 was found to interact with the N-terminal half of MetAP2. In vitro pull-down assays showed that S100A4 associates with MetAP2 in a calcium-dependent manner. In addition, the binding site of S100A4 was found located within the region between amino acid residues 170 and 229 of MetAP2. In vivo interaction of S100A4 with MetAP2 was verified by co-immunoprecipitation analysis. Immunofluorescent staining revealed that S100A4 and MetAP2 were co-localized in both quiescent and basic fibroblast growth factor-treated murine endothelial MSS31 cells, in the latter of which a significant change of intracellular distribution of both proteins was observed. Although the binding of S100A4 did not affect the in vitro methionine aminopeptidase activity of MetAP2, the cytochemical observation suggests a possible involvement of S100A4 in the regulation of MetAP2 activity through changing its localization, thereby modulating the N-terminal methionine processing of nascent substrates. These results may offer an essential clue for understanding the functional role of S100A4 in regulating endothelial cell growth and tumor metastasis.

Tumor suppressor p53 protein is a new target for the metastasis-associated Mts1/S100A4 protein: functional consequences of their interaction

A physical and functional interaction between the Ca(2+)-binding protein Mts1 (S100A4) and the tumor suppressor p53 protein is shown here for the first time. We demonstrate that Mts1 binds to the extreme end of the C-terminal regulatory domain of p53 by several in vitro and in vivo approaches: co-immunoprecipitation, affinity chromatography, and far Western blot analysis. The Mts1 protein in vitro inhibits phosphorylation of the full-length p53 and its C-terminal peptide by protein kinase C but not by casein kinase II. The Mts1 binding to p53 interferes with the DNA binding activity of p53 in vitro and reporter gene transactivation in vivo, and this has a regulatory function. A differential modulation of the p53 target gene (p21/WAF, bax, thrombospondin-1, and mdm-2) transcription was observed upon Mts1 induction in tet-inducible cell lines expressing wild type p53. Mts1 cooperates with wild type p53 in apoptosis induction. Our data imply that the ability of Mts1 to enhance p53-dependent apoptosis might accelerate the loss of wild type p53 function in tumors. In this way, Mts1 can contribute to the development of a more aggressive phenotype during tumor progression.

Stathmin is involved in S100A4-mediated regulation of cell cycle progression

S100A4 is a cell proliferation- and cancer metastasis-related gene. Previous studies have shown that over-expression of S100A4 drives the cells into the S-phase of the cell cycle, with concomitant enhancement of p53 detection. This has led to the postulate that S100A4 could be controlling cell cycle progression by sequestering p53 and abrogating its G1-S checkpoint control. Cells induced by S100A4 to enter the S-phase do successfully negotiate the G2-M checkpoint control. Here we show that S100A4 is also involved in the regulation of control at this checkpoint. Stathmin is known to be associated, together with p53 in controlling G2-M transition. We present evidence that the expression of S100A4 and stathmin genes is up regulated in exponentially growing HeLa cells. They are down regulated in parallel when cell proliferation is inhibited by hyperthermia and 4-hydroxynonenal (4-HNE). We postulate that S100A4 might directly induce stathmin up regulation to enable cells to enter into mitosis. Since wild-type p53 is known to down regulate stathmin expression, we further postulate this might also involve S100A4-mediated sequestration of p53. The expression of heme oxygenase (HO-1), a stress-response protein, has been used to monitor effects of hyperthermia, 12-O-tetradecanoly phorbol 13-acetate (TPA) and 4-HNE. All these treatments induced HO-1 and also when cells growing in serum-deficiency were restored with full serum. HO-1 induction occurred irrespective of S100A4 expression status. HO-1 gene has responsive elements for many angiogenic agents and induces marked neovascularisation of tumours. We suggest therefore that S100A4 may not possess angiogenic properties.

Suppression of metastasis-associated S100A4 gene expression by gamma-interferon in human colon adenocarcinoma cells

S100A4 belongs to the S100 subfamily of calcium-binding proteins and has been suggested to be directly involved in invasion and metastasis of rodent and human tumour cells. The present study demonstrates that interferon gamma (IFN-gamma), but not IFN-alpha and IFN-beta, down-regulates the S100A4 mRNA level in colon adenocarcinoma WiDr cells in time- and dose-dependent manners. The effect was not associated with any cytotoxicity and was specific for the S100A4 mRNA, since the levels of the S100A6 and GAPDH mRNAs were not significantly affected by the treatment. IFN-gamma also strongly suppressed the S100A4 mRNA expression in HT-29 cells, but weakly in Colo201 cells. Flow cytometric analysis revealed that the level of the IFN-gamma receptor expression in Colo201 cells was lower than that in WiDr and HT-29 cells, suggesting that the suppression of the S100A4 expression by IFN-gamma depends on the amount of cell surface IFN-gamma receptor protein. IFN-gamma had no effect on the transcription rate of the S100A4 gene but reduced the stability of the S100A4 mRNA. WiDr cells treated with IFN-gamma showed reduced motile ability, further supporting the assumption that the S100A4 gene product is involved in controlling cell motility.

Apoptosis and cell-cycle arrest in human and murine tumor cells are initiated by isoprenoids

Diverse classes of phytochemicals initiate biological responses that effectively lower cancer risk. One class of phytochemicals, broadly defined as pure and mixed isoprenoids, encompasses an estimated 22,000 individual components. A representative mixed isoprenoid, gamma-tocotrienol, suppresses the growth of murine B16(F10) melanoma cells, and with greater potency, the growth of human breast adenocarcinoma (MCF-7) and human leukemic (HL-60) cells. beta-Ionone, a pure isoprenoid, suppresses the growth of B16 cells and with greater potency, the growth of MCF-7, HL-60 and human colon adenocarcinoma (Caco-2) cells. Results obtained with diverse cell lines differing in ras and p53 status showed that the isoprenoid-mediated suppression of growth is independent of mutated ras and p53 functions. beta-Ionone suppressed the growth of human colon fibroblasts (CCD-18Co) but only when present at three-fold the concentration required to suppress the growth of Caco-2 cells. The isoprenoids initiated apoptosis and, concomitantly arrested cells in the G1 phase of the cell cycle. Both suppress 3-hydroxy-3-methylglutaryl CoA reductase activity. beta-Ionone and lovastatin interfered with the posttranslational processing of lamin B, an activity essential to assembly of daughter nuclei. This interference, we postulate, renders neosynthesized DNA available to the endonuclease activities leading to apoptotic cell death. Lovastatin-imposed mevalonate starvation suppressed the glycosylation and translocation of growth factor receptors to the cell surface. As a consequence, cells were arrested in the G1 phase of the cell cycle. This rationale may apply to the isoprenoid-mediated G1-phase arrest of tumor cells. The additive and potentially synergistic actions of these isoprenoids in the suppression of tumor cell proliferation and initiation of apoptosis coupled with the mass action of the diverse isoprenoid constituents of plant products may explain, in part, the impact of fruit, vegetable and grain consumption on cancer risk.

Calcium-binding protein S100A4 in health and disease

The S100 proteins contain two EF-hand motifs and are of generally unknown function. One of these proteins, S100A4, is an intracellular calcium-binding protein that is present in normal rodent and human cells. In cultured rodent mammary cells, S100A4 is expressed at a higher level in some metastatic epithelial cells than in non-metastatic counterparts. Similarly, in human breast cell lines, S100A4 is present at a higher level in cultured cells from the more malignant, than in those from the more benign tumours. Gene transfer experiments have shown that rodent or human S100A4 is able to induce metastatic capability in otherwise non-metastatic breast tumour cells. Furthermore, expression of rodent S100A4 transgenes can induce metastasis of benign tumours arising in transgenic model systems. Possible mechanisms for the metastasis-inducing effect of S100A4 and the relevance of these observations to human cancer are discussed.

Characterization of a splice variant of metastasis-associated h-mts1 (S100A4) gene expressed in human infiltrating carcinomas of the breast

The h-mts1 (S100A4) is a member of the S100 gene family, coding for a calcium-binding protein. It is a metastasis-associated gene whose expression shows strong correlation with the proliferative potential and invasive and metastatic ability of cancers. In a proportion of human intraductal carcinomas of the breast, a shorter variant h-mts1 transcript (h-mts1v) of approximately 450 nucleotides is expressed. We have characterized the transcript using reverse transcriptase-polymerase chain reaction employing exon-specific oligonucleotides. We show here that the noncoding exon 1a/1b is lost in the variant cDNA. Exons 2 and 3, which code for the protein, seem to be present in the variant isoform. The RT-PCR products obtained using exons 2- and 3-specific oligonucleotides showed a high degree of sequence homology with exons 2 and 3 of the h-mts1 gene. The expression of the variant transcript could be influencing disease progression, albeit not as effectively as the normal unspliced h-mts1 transcript.

Identification of a novel cis-acting element for fibroblast-specific transcription of the FSP1 gene

The FSP1 gene encodes a filament-binding S100 protein with paired EF hands that is specifically expressed in fibroblasts. This led us to look for cis-acting elements in the FSP1 promoter that might engage nuclear transcription factors unique to fibroblasts. The first exon of FSP1 is noncoding, therefore, a series of luciferase reporter minigenes were created containing varying lengths of 5'-flanking sequence, the first intron, and the noncoding region of the second exon. A position and promoter-dependent proximal element between -187 and -88 bp was shown to be active in fibroblasts but not in epithelium. Sequence in the first intron from +777 to +964 had an enhancing effect that was not cell type specific. Hsv TK reporter constructs driven by this promoter/intron cassette in transgenic mice were coexpressed appropriately with FSP1 in tissue fibroblasts. Gel mobility shift competitor assays identified a novel domain, FTS-1 (fibroblast transcription site-1; TTGAT from -177 to -173 bp), that specifically interacts with nuclear extracts from fibroblasts. The necessity of this binding site was confirmed by site-specific mutagenesis. Database searches also turned up putative FTS-1 sites in the early promoter regions of other fibroblast expressed proteins, including the alpha1 and alpha2(I), and alpha1(III) collagens and the alphaSM-actin gene. We hypothesize that the selective engagement of FTS-1 elements may contribute to the mesenchymal phenotype of fibroblasts and perhaps other dedifferentiated cells.

Hypomethylation of the metastasis-associated S100A4 gene correlates with gene activation in human colon adenocarcinoma cell lines

The DNA methylation status of the metastasis-associated S100A4 gene in S100A4-positive and -negative human colon adenocarcinoma cell lines was examined. Northern and Western blot analyses revealed that HT-29, SW480, SW620, WiDr and Colo201 cells expressed S100A4, whereas SW837, LoVo and DLD-1 cells expressed little S100A4. Using CpG methylation-sensitive and -insensitive restriction enzymes and PCR-based methylation assay, it was found that the S100A4 gene in HT-29, SW480, SW620, WiDr and Colo201 cells, but not in SW837, LoVo and DLD-1 cells, was hypomethylated and that the hypomethylation of the second intron was correlated well with the expression of S100A4. 5-Aza-2'-deoxycytidine, an inhibitor of the eukaryotic DNA methyltransferase, induced the expression of the S100A4 gene in SW837, LoVo and DLD-1 cells, while it showed no effect on the expression of the gene in WiDr cells. These results indicate that hypomethylation of the S100A4 gene results in the expression of the gene in colon adenocarcinoma cells.

Expression of metastasis-associated genes h-mts1 (S100A4) and nm23 in carcinoma of breast is related to disease progression

The murine 18A2/mts1 and its human homolog h-mts1 (S100A4), encoding a Ca2+-binding protein belonging to the S-100 family, are associated with high invasive and metastatic potentials of murine tumors, human tumor cell lines in vitro, and human tumors growing as xenografts. The nm23 is a putative metastasis-suppressor gene whose expression has been found to correlate inversely with the metastatic potential of some forms of human cancer. The products of both human genes alter cytoskeletal dynamics, with antagonistic effects. In view of the equivocal association of nm23 with the metastatic potential of human cancer, we suspected that the relative expression of h-mts1 and nm23 might reflect tumor progression more accurately than either of them alone. We describe here the expression of these genes in infiltrating ductal carcinomas of the breast and show that high h-mts1 expression is associated with metastatic spread to the regional lymph nodes. The expression of nm23 on its own did not show a statistically significant inverse correlation with nodal spread. However, the expression status of the two genes, taken together, correlated strongly with the occurrence of nodal metastases. Breast cancers with no detectable expression of h-mts1 were found to be estrogen and progesterone receptor positive. Expression of h-mts1 was not related to tumor differentiation. The clinical data, together with the state of expression of steroid receptors and the expression levels of h-mts1 and nm23 genes, were analyzed using artificial neural networks for accuracy in predicting nodal spread of the carcinomas. These analyses support the conclusion that, overall, h-mts1 expression appears to be associated with and indicative of more aggressive disease. Complemented with nm23, h-mts1 could provide a powerful marker of breast cancer prognosis.

Heat shock modulates the expression of the metastasis associated gene MTS1 and proliferation of murine and human cancer cells

Mts1 is a metastasis-associated gene of the S-100 gene family and codes for a Ca2+-binding protein. It is highly expressed in murine and human cancers of high invasive and metastatic potential. Recent work has shown that the mts1 protein might be involved in cell cycle regulation. An upregulation of its expression drives cells into the S phase, together with an enhanced expression of p53 phosphoprotein, which has led to the suggestion that mtsl protein might be sequestering p53 thereby abrogating the G1-S checkpoint control normally exerted by p53. Preliminary studies showed that expression of mts1 is downregulated by hyperthermia. We present evidence that in murine BL6 melanoma cells and human HUT cells that hyperthermia downregulates the mts1 gene. It is also downregulated in heat-resistant variants of the B16 melanoma and HUT cells. In parallel, there is a decrease in the size of the S phase fraction and an increase in the doubling time of cells. Cell subjected to hyperthermia show an 2- to 3.5-fold increase in the expression of HSP28 which has been shown to possess a proliferation inhibitory action. It is postulated that a complete regulatory loop involving mtsl, p53, and HSP28 might be involved in cell proliferation.

Early role of Fsp1 in epithelial-mesenchymal transformation

A seamless plasticity exists among cells shifting between epithelial and mesenchymal phenotypes during early development and again later, in adult tissues, following wound repair or organ remodeling in response to injury. Fsp1, a gene encoding a fibroblast-specific protein associated with mesenchymal cell morphology and motility, is expressed during epithelial-mesenchymal transformations (EMT) in vivo. In the current study, we identified several cytokines that induce Fsp1 in cultured epithelial cells. A combination of these factors, however, was most efficacious at completing the process of EMT. The optimal combination identified were two of the cytokines classically associated with fibrosis, i.e., transforming growth factor-beta1 (TGF-beta1) and epidermal growth factor (EGF). To confirm that it was the induction of Fsp1 by these cytokines mediating EMT, we used antisense oligomers to block Fsp1 production and subsequently measured cell motility and markers of EMT phenotype. The antisense oligomers suppressed Fsp1 expresison and epithelial transformation; therefore, we conclude that the appearance of Fsp1 is an important early event in the pathway toward EMT.

Repression of the candidate tumor suppressor gene S100A2 in breast cancer is mediated by site-specific hypermethylation

The calcium-binding protein S100A2 is expressed in normal breast tissue but downregulated during breast cancer progression. Hence it was previously identified as a candidate tumor suppressor gene. In this report, we investigated the molecular basis of S100A2 gene expression in normal and tumorigenic human breast epithelial cells. We cloned the gene coding for S100A2 including its 5' flanking region. To locate positively or negatively acting elements responsible for transcriptional regulation, promoter deletion studies were performed. Results from these experiments demonstrate that an enhancer element is located 1.2 kb upstream of the transcription start site. This element contains two AP1-like binding sites suggesting that transcriptional activation of S100A2 might be mediated by immediate early genes. Interestingly, the enhancer stimulates transcription in both normal and tumorigenic cells, indicating that repression of endogenous S100A2 transcription in tumorigenic cells might lie at an epigenetic level. Indeed, the proximal promoter region was found, by genomic sequencing, to be unmethylated in normal but hypermethylated in tumorigenic cells. Hypermethylation of the promoter at the same CpG sites was also found in a breast cancer biopsy. In addition, site specific in vitro methylation led to reduced expression of the S100A2 gene in normal cells. These experiments provide strong evidence that S100A2 repression in tumor cells is mediated by site-specific methylation. Since transcription of a number of known tumor suppressor genes is also repressed by methylation, our observation is consistent with the suggestion that S100A2 might have a tumor suppressor function.

Ca2+-dependent interaction of S100A2 with muscle and nonmuscle tropomyosins

Zero-length chemical crosslinking with 1-ethyl-3-[3-(dimethyl amino)propyl]carbodiimide (EDC) indicated an association of the Ca2+-binding protein S100A2 with tropomyosin (TM) in vitro. The mobility of the crosslinked product on SDS-PAGE gels indicated the formation of a 1:1 complex between S100A2 and TM and the interaction was Ca2+ dependent. Monoclonal antibodies were raised against S100A2 and used to determine its cellular localization in the porcine epithelial cell line LLC PK1. It was found that the localization of S100A2 depended on the differentiation state of the cells, being absent from actin stress fibers in sparsely seeded cultures, but present in the actin-containing microvilli characteristic of differentiated cells. Immunoprecipitations of [35S]methionine-labeled extracts using S100A2 as well as TM-specific antibodies failed to co-precipitate TM and S100A2, indicating a transient association between these two molecules in solution. Affinity chromatography of cell extracts on immobilized recombinant TMs, however, confirmed the Ca2+-dependent interaction between S100A2 and both muscle TMs as well as with high and low molecular mass nonmuscle TMs, suggesting that the binding site resides in one of the conserved regions of TM. Our data demonstrate the possible interaction of S100A2 with TM that is not bound to the microfilaments and indicate a differentiation-related function for S100A2 in LLC PK1 cells. The possible functional implications of this interaction are discussed.