Calcyclin (S100A6) regulates pulmonary fibroblast proliferation, morphology, and cytoskeletal organization in vitro

Molecular Cloning and Characterization ofSGT1.2, a Novel Splice Variant ofHomo sapiens SGT1

SGT1.2, a novel splice variant of Homo sapiens SGT1 was isolated from a human fetal brain cDNA library. This cDNA is 1404 bp and contains an open reading frame from 68 to 1165 encoding a putative protein of 365 amino acids (SGT1.2) that share 90% identities to Homo sapiens SGT1, suppressor of G2 allele of SKP1 at protein level. RPS-BLAST searching revealed that SGT1.2 have a TPR domain, a p23 domain, a SGS domain and a CS domain. According to the search of the human genome database, SGT1.2 was mapped to human chromosome 13q14.13. Reversed transcription-polymerase chain reaction analysis indicated that it widely expressed in human adult tissues.

Multistep pathogenesis of leukemia via the MLL-AF4 chimeric gene/Flt3 gene tyrosine kinase domain (TKD) mutation-related enhancement of S100A6 expression

OBJECTIVE

Concerning MLL-AF4 leukemogenesis, previous mouse models suggest that the tumorigenesis capacity of MLL-AF4 alone is insufficient for causing leukemia. Based on the finding that an Fms-like tyrosine kinase 3 (Flt3) gene mutation in the tyrosine kinase domain (TKD) was observed in approximately 15% of mixed lineage leukemia (MLL), we investigated synergistic leukemogenesis effects of the two genes in vitro.

MATERIALS AND METHODS

In a mouse interleukin-3 (IL-3)-dependent cell line, 32Dc, expression of MLL-AF4 and mutant Flt3 was induced using a lentiviral vector. We analyzed apoptosis induction in the absence of IL-3 and the granulocyte colony-stimulating factor-related induction of differentiation, gene expression profiling, and the mechanism involved in the synergistic effects of MLL-AF4 and Flt3-TKD.

RESULTS

Neither Flt3-expressing 32Dc (32Dc(Flt3-TKD)) nor MLL-AF4-expressing 32Dc (32Dc(MLL-AF4)) acquired IL-3-independent proliferative capacity in semisolid/liquid media. However, Flt3-TKD+MLL-AF4-expressing 32Dc (32Dc(Flt3-TKD+MLL-AF4)) acquired a non-IL-3-dependent proliferative capacity by inhibiting apoptosis in the two media. The 32Dc(Flt3-TKD) and 32Dc(MLL-AF4) cells differentiated into granulocytes in the presence of granulocyte colony-stimulating factor. However, in the 32Dc(Flt3-TKD+MLL-AF4) cells, there was no differentiation. Subsequently, we performed gene expression profiling. The enhancement of Hox genes expression was not identified. However, expression of S100A6 was synergistically enhanced in the presence of both MLL-AF4 and Flt3-TKD genes. Moreover, anti-S100A6 small interfering RNA downregulated leukemic proliferation.

CONCLUSION

We conclude that their synergistic enhancement of S100A6 expression plays an important role in MLL-AF4-associated leukemogenesis.

Expression of cyclophilin B is associated with malignant progression and regulation of genes implicated in the pathogenesis of breast cancer

Cyclophilin B (CypB) is a 21-kDa protein with peptidyl-prolyl cis-trans isomerase activity that functions as a transcriptional inducer for Stat5 and as a ligand for CD147. To better understand the global function of CypB in breast cancer, T47D cells with a small interfering RNA-mediated knockdown of CypB were generated. Subsequent expression profiling analysis showed that 663 transcripts were regulated by CypB knockdown, and that many of these gene products contributed to cell proliferation, cell motility, and tumorigenesis. Real-time PCR confirmed that STMN3, S100A4, S100A6, c-Myb, estrogen receptor alpha, growth hormone receptor, and progesterone receptor were all down-regulated in si-CypB cells. A linkage analysis of these array data to protein networks resulted in the identification of 27 different protein networks that were impacted by CypB knockdown. Functional assays demonstrated that CypB knockdown also decreased cell growth, proliferation, and motility. Immunohistochemical and immunofluorescent analyses of a matched breast cancer progression tissue microarray that was labeled with an anti-CypB antibody demonstrated a highly significant increase in CypB protein levels as a function of breast cancer progression. Taken together, these results suggest that the enhanced expression of CypB in malignant breast epithelium may contribute to the pathogenesis of this disease through its regulation of the expression of hormone receptors and gene products that are involved in cell proliferation and motility.

Expression of S100A6 in cardiac myocytes limits apoptosis induced by tumor necrosis factor-alpha

S100A6 is induced in myocardium post-infarction in vivo and in response to growth factors and inflammatory cytokines in vitro. Forced expression of S100A6 in cardiomyocytes inhibits regulation of cardiac specific gene expression in response to trophic stimulation. To define regulation and function of S100A6, we characterized the human S100A6 promoter and mapped upstream regulatory elements in rat neonatal cardiac myocytes, fibroblasts, and vascular smooth muscle cells and defined a functional role for S100A6 in tumor necrosis factor-alpha-induced myocyte apoptosis. The functional S100A6 promoter was localized to region -167/+134 containing 167 upstream base pairs. The S100A6 promoter is regulated by positive (-361/-167 and -588/-361) and negative (-1371/-1194) elements. Tumor necrosis factor-alpha induced the maximal S100A6 promoter and transcription factor NF-kappaB (p65 subunit). Electrophoretic mobility shift showed that tumor necrosis factor-alpha induced p65 binding to a potential NF-kappaB-binding site at -460/-451. Chromatin immunoprecipitation analysis revealed p65 is recruited to the S100A6 promoter upon tumor necrosis factor-alpha stimulation. The NF-kappaB inhibitor caffeic acid phenethyl ester and mutation of the NF-kappaB-binding site inhibited S100A6 promoter activation by tumor necrosis factor-alpha. Tumor necrosis factor-alpha induced cardiac myocyte apoptosis. Specific inhibition of S100A6 using a small interfering RNA directed against S100A6 potentiated tumor necrosis factor-alpha-induced myocyte apoptosis, whereas overexpression of S100A6 by gene transfer prevented tumor necrosis factor-alpha-induced myocyte apoptosis by interfering with p53 phosphorylation. These results demonstrate that S100A6 is induced by tumor necrosis factor-alpha via an NF-kappaB-dependent mechanism, serving a role in homeostasis to limit tumor necrosis factor-alpha-induced apoptosis by regulating p53 phosphorylation.

Expression and clinical significance of CacyBP/SIP in pancreatic cancer

AIMS

Calcyclin-binding protein or Siah-1-interacting protein (CacyBP/SIP), a component of the ubiquitin-mediated proteolysis, could bind SKP1-CUL1-F box protein complex and participate in beta-catenin degradation, which was found to be related to the malignant phenotypes of gastric cancer and renal cancer. However, the role of CacyBP/SIP in pancreatic cancer progression still remains unclear. Therefore, the aim of the present study was to investigate the expression and clinical significance of CacyBP/SIP in pancreatic cancer.

METHODS

Immunohistochemistry was carried out on paraffin-embedded sections of pancreatic cancer and normal pancreatic tissues. In addition, Western blot and semiquantitative RT-PCR were carried out to analyze mRNA and protein expression of CacyBP/SIP in 8 pairs of freshly resected pancreatic cancer and their adjacent nontumorous tissue.

RESULTS

CacyBP/SIP expression was significantly increased in pancreatic cancer tissue (28/68 or 41.2%) and correlated with differentiation degree, higher TNM (tumor, node, metastasis) stage and distance metastasis. Also, mRNA and protein expression of CacyBP/SIP were found to be at higher levels in almost all cancer tissues compared to adjacent tissues.

CONCLUSIONS

CacyBP/SIP protein might play an important role in the process of pancreatic carcinogenesis and high-level CacyBP/SIP expression might be related to the malignant potential of pancreatic cancer.

S100A6 expression and function in human osteosarcoma

There is a critical need to identify markers that can accurately identify existing or predict future metastatic disease in patients with osteosarcoma since the majority of patients present with undetectable micrometastatic disease. We previously reported S100A6 is overexpressed in human osteosarcoma and increased expression of S100A6 by immunohistochemistry correlated with decreased clinical metastasis. We have established 11 primary cultures from biopsies of patients with osteosarcoma and ten of the 11 primary cultures have increased expression of S100A6 relative to normal human osteoblasts. To further explore possible mechanisms for metastasis suppression previously reported, we used in this report siRNA-mediated knockdown of S100A6 in four commonly used human osteosarcoma lines, then examined their cell adhesion, migration, and invasion properties. Knockdown of S100A6 expression inhibited cell adhesion and promoted cell migration and invasion in these lines. Conversely, S100A6 overexpression enhanced cell adhesion and inhibited cell invasion. Our data demonstrate S100A6 is commonly overexpressed in human osteosarcoma. S100A6 may inhibit osteosarcoma metastasis by promoting cell adhesion and inhibiting cell motility and invasion. Thus, S100A6 may be considered a potential marker for human osteosarcoma with prognostic value for identifying patients without metastases.

Identification of a novel, functional role for S100A13 in invasive lung cancer cell lines

The S100 family is a group of small, calcium-binding proteins with at least 20 distinct members in humans. Several of these have been associated with cancer invasion or metastasis in recent studies. Transcriptional analysis of gene expression in a panel of lung cancer-derived cell lines identified S100A13 as being associated with a more aggressive invasive phenotype in vitro. Hierarchical clustering grouped this gene with several others that have established functional roles in this phenotype both in vitro and in vivo (ICAM1, CD34, EFNB2 and HGF) as well as genes involved in processes such as angiogenesis (TEM7, JAG2). Depletion of cellular S100A13 mRNA levels by RNAi in highly invasive lung cancer cell lines resulted in a 50-80% decrease in their invasive potential in an in vitro assay. This reduction could not be accounted for by reduced cellular proliferation. Conversely, transient overexpression of exogenous S100A13 in less invasive cell lines had no impact on invasive potential suggesting that upregulation of S100A13 expression alone is insufficient to induce the phenotype. We conclude that S100A13 is involved in but not capable of inducing invasion, since elevated S100A13 mRNA expression correlates with a more invasive phenotype and in vitro invasion can be inhibited by reduced S100A13 expression.

Upregulated expression of S100A6 in human gastric cancer

OBJECTIVE

The expression of S100A6 (calcyclin), a member of the S100 calcium binding protein family, is elevated in a number of malignant tumors, but there have been few reports about its expression in gastric cancer. The aim of this study was to investigate its expression regulations in human gastric cancer and noncancerous mucosa, and the response to chemotherapeutic drugs in the gastric cancer cell line.

MATERIALS AND METHODS

In one matched gastric cancer sample pair, the serial analysis of gene expression (SAGE) experiment was conducted to compare the gene expression profiles between cancerous and adjacent tissues. To detect the expression regulations among more cancerous tissues, microarrays were carried out and real-time RT-PCR was conducted to validate the results. At the protein level, Western blot and tissue microarray (TMA) examination were further used to verify S100A6 expression. The regulation detection of S100A6 with flurouracil and doxorubicin at the mRNA and protein level was performed in the SGC7901 cell line.

RESULTS

With the SAGE strategy, five times more S100A6 tags were identified in cancer tissues than in normal tissues. With the cDNA microarray, S100A6 was found to be significantly upregulated in 21 of 42 (50%) nonselective gastric cancers. In 10 other paired samples, the upregulation of S100A6 was consolidated with RT-PCR and Western blot analysis as well. A total of 14 endoscopy-sectioned gastric noncancerous lesions and corresponding normal gastric mucosa were also applied to profile the gene expression; both cDNA microarray and RT-PCR demonstrated no significant alterations of S100A6 at the mRNA level. TMA examination showed that 34 of 52 (65.4%) cancer samples were positively stained, while only 17 of 80 (21.3%) noncancerous lesions were positively detected and all nine normal mucosae were detected to be negative. An in vitro experiment showed that in the gastric cell line SGC-7901, S100A6 mRNA was detected to be upregulated from 24 to 72 h after treatment with 5 mg/L 5-flurouracil or 0.3 mg/L doxorubicin, and there were two wave upregulations of the S100A6 protein.

CONCLUSION

The observed regulated expression of S100A6 suggests that it is associated with gastric cancer tumorigenesis and quantitation of S100A6 is a promising tool for diagnosis of gastric cancer.

Up-regulation, modification, and translocation of S100A6 induced by exposure to ionizing radiation revealed by proteomics profiling

The cellular response to genotoxic stress is a complex cascade of events including altered protein expression, interactions, modifications, and relocalization, leading to cell cycle arrest and DNA repair or to apoptosis. p53 protein has a central role in this process, and p53 status is an important factor in the response of a tumor to genotoxic anticancer therapy. We studied p53-related changes postexposure to ionizing radiation using top-down mass spectrometry. Initially two cell lines were compared, HCT116 p53 wild type (wt) and p53(-/-), in a time course study postirradiation. In the p53 wt cell line a striking increase of a 10.2-kDa protein was detected, and this protein was identified with MS/MS analysis as S100A6. Further MS profiling led to detection of two post-translationally modified variants of S100A6, namely glutathionylated and cysteinylated forms. In p53 wt cells, a specific shift from glutathionylated to cysteinylated S100A6 occurred postirradiation. The p53 dependence of this specific change in protein level and modification pattern of S100A6 postirradiation was confirmed in a panel of four lung cancer cell lines (H23, U1810, H69, and A549) with different p53 status and using small interfering RNA against p53. Interestingly the closely related S100 family protein S100A4 showed the same changes in modification pattern post-ionizing radiation in the p53 wt lung cancer cell line, and S100A4 also showed p53-dependent expression. Using confocal microscopy, relocalization of S100A6 from nucleus to cytosol and a colocalization with tropomyosin in stress fibers was detected in A549 cells postirradiation. This relocalization coincided with the change in S100A6 modification pattern. Based on these results, we suggest that S100A6 and S100A4 are regulated via redox modifications in vivo and that these proteins are involved in the cellular response to genotoxic stress.

Human X-box binding protein-1 confers both estrogen independence and antiestrogen resistance in breast cancer cell lines

Human X-box binding protein-1 (XBP1) is an alternatively spliced transcription factor that participates in the unfolded protein response (UPR), a stress-signaling pathway that allows cells to survive the accumulation of unfolded proteins in the endoplasmic reticulum lumen. We have previously demonstrated that XBP1 expression is increased in antiestrogen-resistant breast cancer cell lines and is coexpressed with estrogen receptor alpha (ER) in breast tumors. The purpose of this study is to investigate the role of XBP1 and the UPR in estrogen and antiestrogen responsiveness in breast cancer. Overexpression of spliced XBP1 [XBP1(S)] in ER-positive breast cancer cells leads to estrogen-independent growth and reduced sensitivity to growth inhibition induced by the antiestrogens Tamoxifen and Faslodex in a manner independent of functional p53. Data from gene expression microarray analyses imply that XBP1(S) acts through regulation of the expression of ER, the antiapoptotic gene BCL2, and several other genes associated with control of the cell cycle and apoptosis. Testing this hypothesis, we show that overexpression of XBP1(S) prevents cell cycle arrest and antiestrogen-induced cell death through the mitochondrial apoptotic pathway. XBP1 and/or the UPR may be a useful molecular target for the development of novel predictive and therapeutic strategies in breast cancer.

S100A6 is increased in a stepwise manner during pancreatic carcinogenesis: clinical value of expression analysis in 98 pancreatic juice samples

There are few reports describing the diagnostic significance of S100A6 expression in clinical samples obtained from patients with pancreatic disease. In the present study, we measured S100A6 expression in pancreatic tissues and juice to evaluate its involvement in pancreatic carcinogenesis. We did quantitative real-time reverse transcription-PCR to measure mRNA expression in microdissected cells and pancreatic juice samples. Microdissected invasive ductal carcinoma and intraductal papillary mucinous neoplasm (IPMN) cells expressed significantly higher levels of S100A6 than did microdissected pancreatitis-affected epithelial and normal cells (all comparison; P < 0.008). Median levels of S100A6 in invasive ductal carcinoma were higher than those in IPMN, and those in pancreatitis-affected epithelial cells tended to be higher than those in normal cells, although these differences were not statistically significant. In analyses of pancreatic juice, IPMN and pancreatic cancer samples expressed significantly higher levels of S100A6 than did chronic pancreatitis samples (both; P < 0.017), but levels in pancreatic cancer and IPMN samples did not differ form each other. Receiver operating characteristic (ROC) curve analysis revealed that measurement of S100A6 was useful for discriminating cancer (area under the ROC curve, 0.864) or IPMN (area under the ROC curve, 0.749) from chronic pancreatitis. The present data suggest that expression of S100A6 is increased in a stepwise manner during pancreatic carcinogenesis and may be a biomarker for evaluating malignant potential. Measurement of S100A6 in pancreatic juice may be useful to detect early pancreatic cancer or identify individuals with high-risk lesions that may progress to pancreatic cancer.

Screening and cloning for proteins transactivated by the PS1TP5 protein of hepatitis B virus: A suppression subtractive hybridization study

AIM: To clone and identify human genes transactivated by PS1TP5 by constructing a cDNA subtractive library with suppression subtractive hybridization (SSH) technique.

METHODS: SSH and bioinformatics techniques were used for screening and cloning of the target genes transactivated by PS1TP5 protein. The mRNA was isolated from HepG2 cells transfected with pcDNA3.1(-)-myc-his(A)-PS1TP5 and pcDNA3.1(-)-myc-his(A) empty vector, respectively, and SSH technique was employed to analyze the differentially expressed DNA sequence between the two groups. After digestion with restriction enzyme RsaI, small size cDNAs were obtained. Then tester cDNA was divided into two groups and ligated to the specific adaptor 1 and adaptor 2, respectively. The tester cDNA was hybridized with driver cDNA twice and subjected to nested PCR for two times, and then subcloned into T/A plasmid vectors to set up the subtractive library. Amplification of the library was carried out with E. coli strain DH5α. The cDNA was sequenced and analyzed in GenBank with Vector NTI 9.1 and NCBI BLAST software after PCR amplification.

RESULTS: The subtractive library of genes transactivated by PS1TP5 was constructed successfully. The amplified library contained 90 positive clones. Colony PCR showed that 70 clones contained 200-1000-bp inserts. Sequence analysis was performed in 30 clones randomly, and the full-length sequences were obtained by bioinformatics technique. Altogether 24 coding sequences were obtained, which consisted of 23 known and 1 unknown. One novel gene with unknown functions was found and named as PS1TP5TP1 after being electronically spliced, and deposited in GenBank (accession number: DQ487761).

CONCLUSION: PS1TP5 is closely correlated with immunoregulation, carbohydrate metabolism, signal transduction, formation mechanism of hepatic fibrosis, and occurrence and development of tumor. Understanding PS1TP5 transactive proteins may help to bring some new clues for further studying the biological functions of pre-S1 protein.

OCIA domain containing 2 is highly expressed in adenocarcinoma mixed subtype with bronchioloalveolar carcinoma component and is associated with better prognosis

Although lung adenocarcinoma is a major cause of cancer death worldwide, details of its molecular carcinogenesis and stepwise progression are still unclear. To characterize the sequential progression from bronchioloalveolar adenocarcinoma of the lung (BAC, in situ carcinoma) to adenocarcinoma mixed subtype with BAC component polymerase chain reaction-based cDNA suppression subtractive hybridization (SSH) was carried out using two representative cases of BAC (non-invasive tumors) and adenocarcinoma mixed subtype with BAC (invasive tumors). Through differential screening, virtual reverse northern hybridization and quantitative real-time reverse-transcription-polymerase chain reaction (qRT-PCR) we selected five genes (TncRNA, OCIAD2, ANXA2, TMED4 and LGALS4) that were expressed at significantly higher levels in invasive adenocarcinoma mixed subtype with BAC than in BAC. After in situ hybridization and qRT-PCR analyses, we confirmed that only the OCIAD2 gene showed significantly higher expression in the tumor cells of invasive adenocarcinoma mixed subtype with BAC than in BAC (P = 0.026). We then carried out in situ hybridization of OCIAD2 in 56 adenocarcinoma mixed subtype with BAC component and assessed the correlation between OCIAD2 expression and clinicopathological features. In contrast to our expectation, the patients with OCIAD2 expression showed a better clinical outcome than those without OCIAD2 expression, and OCIAD2 expression showed an inverse correlation with lymphatic invasion, blood vessel invasion and lymph node metastasis. These results suggest that OCIAD2 begins to express at the progression from in situ to invasive carcinoma, and is associated with the favorable prognosis of adenocarcinoma mixed subtype with BAC component.

Calcyclin binding protein promotes DNA synthesis and differentiation in rat neonatal cardiomyocytes

During cardiac muscle development, most cardiomyocytes permanently withdraw from the cell cycle. Previously, by suppressive subtractive hybridization, we identified calcyclin-binding protein/Siah-interacting protein (CacyBP/SIP) as one of the candidates being upregulated in the hyperplastic to hypertrophic switch, suggesting an important role of CacyBP/SIP in cardiac development. To show the importance of CacyBP/SIP during myoblast differentiation, we report here that CacyBP/SIP is developmentally regulated in postnatal rat hearts. The overexpression of CacyBP/SIP promotes the differentiation and DNA synthesis of H9C2 cells and primary rat cardiomyocytes, as well as downregulates the expression of beta-catenin. Besides, CacyBP/SIP promotes the formation of myotubes and multinucleation upon differentiation. To investigate the cardioprotective role of CacyBP/SIP in cardiomyocytes, a hypoxia/reoxygenation model was employed. We found that CacyBP/SIP was upregulated during myocardial infarction (MI) and hypoxia/reoxygenation. As a conclusion, CacyBP/SIP may play a role in cardiomyogenic differentiation and possibly protection of cardiomyocytes during hypoxia/reoxygenation injury.

The role of S100A6 in pancreatic cancer development and its clinical implication as a diagnostic marker and therapeutic target

Recent microarray analyses showed that the S100 family contains members that are candidate diagnostic markers or therapeutic targets. In the present study, to evaluate the involvement of S100A6 in pancreatic cancer and its clinical usefulness for diagnosis, we examined S100A6 mRNA expression in pancreatic tissues and pancreatic juice from patients with different pancreatic diseases. To investigate the role of S100A6 in carcinogenesis of pancreatic cancer and the potential of S100A6 as a diagnostic marker for early detection of pancreatic cancer, we did immunohistochemistry and microdissection-based mRNA analysis of pancreatic normal ducts, pancreatic intraepithelial neoplasias, and invasive ductal carcinomas. We also used in vitro experiments and microarray analysis with RNA interference to evaluate the functional role of S100A6 and its potential as a therapeutic target for pancreatic cancer. S100A6 mRNA levels were significantly higher in carcinoma specimens than in nonneoplastic tissues. In pancreatic juice, there was a significant difference in S100A6 expression between patients with carcinoma and those with nonneoplastic disease. Receiver operating characteristic curves revealed that S100A6 might be a useful marker for diagnosis of pancreatic cancer. Immunohistochemistry and microdissection-based analysis showed differential expression of S100A6 among normal ducts, pancreatic intraepithelial neoplasias, and invasive ductal carcinomas. In vitro data showed that inhibition of S100A6 decreased proliferation and invasiveness of cancer cells, and these findings were supported by microarray data. Our present results suggest that quantitation of S100A6 mRNA is a promising tool for diagnosis of pancreatic cancer, and that S100A6 may be a promising therapeutic target for pancreatic cancer.

Proteomics analysis revealed changes in rat bronchoalveolar lavage fluid proteins associated with oil mist exposure

Exposure to oil mist has been associated with a variety of acute and chronic respiratory effects. Using proteomics approaches to investigate exposure-associated proteins may provide useful information to understand the mechanisms of associated respiratory effects. The aim of this study was to investigate changes in rat bronchoalveolar lavage fluid proteins associated with oil mist exposure using nano-HPLC-ESI-MS/MS. The results revealed that 29 proteins exhibited significant changes after exposure. These proteins included surfactant-associated proteins (SP-A and SP-D), inflammatory proteins (complement component 3, immunoglobulins, lysozyme, etc.), growth factors (e.g., transforming growth factor alpha (TGF-alpha)), calcium-binding proteins (calcyclin, calgranulin A, calreticulin, and calvasculin), and other proteins (e.g., cathepsin D, saposin, and intestinal trefoil factor). To further evaluate changes in protein levels, a simple quantitative strategy was developed in this study. A large decrease in protein levels of SP-A and SP-D (0.24- and 0.38-fold, respectively) following exposure was observed. In contrast, protein levels of TGF-alpha and calcium-binding proteins were significantly increased (4.46- and 1.4-1.8-fold, respectively). Due to the diverse functions of these proteins, the results might contribute to understand the mechanisms involved in lung disorders induced by oil mist exposure.

Binding and functional characteristics of two E-box motifs within the S100A6 (calcyclin) gene promoter

S100A6 (calcyclin) is a small calcium-binding protein of the S100 family often associated with cancer and metastasis. We have previously shown that the E-box sequence at position -283/-278 of the S100A6 gene promoter interacts with USF transcription factor and contributes to promoter transcriptional activity. We now present evidence that a second E-box motif at position -593/-588 of the promoter also binds USF and that the USF1/USF2 heterodimer is the prevailing dimeric form of the transcription factor bound. Using the chromatin immunoprecipitation assay (ChIP), we show that USF is bound in vivo to the E-box regulatory element(s). Depletion of the endogenous USF pool by means of a decoy oligonucleotide evokes a severe inhibition of S100A6 gene promoter activity. Furthermore, we show that S100A6 gene promoter activity can be stimulated by palmitate and that mutation of the -283/-278 E-box sequence completely blocks this stimulation.

Increased expression of S100A6 is associated with decreased metastasis and inhibition of cell migration and anchorage independent growth in human osteosarcoma

While most osteosarcoma patients have metastatic or micrometastatic lesions, less than 15% of them have clinically detectable metastatic diseases at presentation. To identify potential markers that may predict osteosarcoma metastasis, we analyzed the expression of S100A6 in 50 osteosarcoma cases and found that 84% of the analyzed specimens stained positive for S100A6. There is a trend towards decreased clinically evident metastasis with increased S100A6 staining. Overexpression of S100A6 in osteosarcoma cells decreases cell motility and anchorage independent growth on collagen gels. Our findings provide evidence that, while S100A6 is commonly overexpressed in human osteosarcoma, loss of its expression correlates with a metastatic phenotype.

Expression and hormonal regulation of calcyclin-binding protein (CacyBP) in the mouse uterus during early pregnancy

Calcyclin-binding protein (Siah-1-Interacting Protein, CacyBP/SIP), is a calcium signaling protein involved in the degradation of beta-catenin, however, little is known about its role in reproductive biology. The present study was to character its temporospatial expression pattern and regulation in mouse uterus and to investigate whether it plays a role in the regulation of normal endometrial events. While prominently expressed in both luminal and glandular epithelia, CacyBP underwent dynamic changes during early pregnancy. CacyBP expression was observed weakly from days 1-4. An intense accumulation in luminal and glandular epithelia as well as decidua surrounding the embryo at later stages (days 5-7) was observed. Most notably, CacyBP accumulation in trophoblast was pronounced at day 7. Using ovariectomized and pseudopregnant mice, we found that progesterone (P(4)) and 17beta-estradiol (E(2)) led to increased expression of CacyBP gene and this could be abolished by Ru486 and tamoxifen, respectively. Antisense oligonucleotides (ODNs) against CacyBP significantly inhibited cultured endometrial stromal cells' (ESCs) apoptosis induced by UV irradiation. Injection of antisense ODNs into mouse uterine horn severely impaired the number of implanted blastocysts. Taken together, our results suggested that CacyBP expression was positively regulated by P(4) and E(2). CacyBP may be involved in the regulation of endometrial cell apoptosis during early pregnancy and play an important role in mouse endometrial events such as pregrancy establishment.

Potato homologs of Arabidopsis thaliana genes functional in defense signaling--identification, genetic mapping, and molecular cloning

Defense against pests and pathogens is a fundamental process controlled by similar molecular mechanisms in all flowering plants. Using Arabidopsis thaliana as a model, steps of the signal transduction pathways that link pathogen recognition to defense activation have been identified and corresponding genes have been characterized. Defense signaling (DS) genes are functional candidates for controlling natural quantitative variation of resistance to plant pathogens. Nineteen Arabidopsis genes operating in defense signaling cascades were selected. Solanaceae EST (expressed sequence tag) databases were employed to identify the closest homologs of potato (Solanum tuberosum). Sixteen novel DS potato homologs were positioned on the molecular maps. Five DS homologs mapped close to known quantitative resistance loci (QRL) against the oomycete Phytophthora infestans causing late blight and the bacterium Erwinia carotovora subsp. atroseptica causing blackleg of stems and tuber soft rot. The five genes are positional candidates for QRL and are highly sequence related to Arabidopsis genes AtSGT1b, AtPAD4, and AtAOS. Full-length complementary DNA and genomic sequences were obtained for potato genes StSGT1, StPAD4, and StEDS1, the latter being a putative interactor of StPAD4. Our results form the basis for further studies on the contributions of these candidate genes to natural variation of potato disease resistance.

Proteins and protein pattern differences between glioma cell lines and glioblastoma multiforme

INTRODUCTION

Research into the pathogenesis, molecular signaling, and treatment of glioblastoma multiforme (GBM) has traditionally been conducted using cell lines derived from malignant gliomas. We compared protein expression patterns between solid primary GBMs and GBM cell lines to identify proteins whose expression may be altered in cell culture.

METHODS

We cultured cell lines U87, U118, U251, and A172 and used tissue-selective microdissection of eight primary GBMs to obtain pure populations of tumor cells, which we studied using two-dimensional gel electrophoresis (2DGE) and examined using differential expression software. Select protein targets expressed differentially between GBM tumors and GBM cell lines were sequenced using tandem mass spectrometry.

RESULTS

Analysis of the primary GBM tumor samples (n = 8) and the GBM cell lines revealed reproducibly similar proteomic patterns for each group, which distinguished tumors from the cell lines. Gels contained up to 500 proteins that were consistently identified in the pH 4 to 7 range. Comparison of proteins identified in the GBM tumors and in the cell lines showed approximately 160 proteins that were gained and 60 proteins that were lost on culture. Using normalized intensity patterns from the 2DGE images, ANOVA tests were done and statistically significant spots were identified. Seven proteins found in the cell lines were significantly increased when compared with the GBM tumors (P < 0.05), whereas 10 proteins were significantly decreased from cell lines compared with the GBM tumors. Proteins identified included transcription factors, tumor suppressor genes, cytoskeletal proteins, and cellular metabolic proteins.

CONCLUSION

Global protein and proteomic differences were identified between primary GBM tumor samples and GBM cell lines. The proteins identified by 2DGE analysis elucidate some of the selection pressures of in vitro culture, help accentuate the advantages and limitations of cell culture, and may aid comprehension of gliomagenesis and enhance development of new therapeutics.

The Ankrd2, Cdkn1c and Calcyclin Genes are Under the Control of MyoD During Myogenic Differentiation

Skeletal muscle development requires the coordinated expression of numerous transcription factors to control the specification of the muscle fate in mesodermal cells and the differentiation of the committed myoblasts into functional contractile fibers. The bHLH transcription factor MyoD plays a key role in these processes, since its forced expression is sufficient to induce the myogenesis in a variety of non-muscle cells in culture. Consistent with this observation, the majority of skeletal muscle genes require MyoD to activate their own transcription. In order to identify novel MyoD-target genes we generated C2C12 MyoD-silenced clones, and used a muscle-specific cDNA microarray to study the induced modifications of the transcriptional profile. Gene expression was analyzed at three different stages in differentiating MyoD(-)C2C12 myoblasts. These microarray data sets identified many additional uncharacterized downstream MyoD transcripts that may play important functions in muscle cell differentiation. Among these genes, we concentrated our study on the cell cycle regulators Cdkn1c and calcyclin and on the muscle-specific putative myogenic regulator Ankrd2. Bioinformatic and functional studies on the promoters of these genes clarified their dependence on MyoD activity. Clues of other regulatory mechanisms that might interact with the principal bHLH transcription factor have been revealed by the unexpected up-regulation in MyoD(-) cells of these novel (and other) target transcripts, at the differentiation stage in which MyoD became normally down-regulated.

FGF-2, IL-1β and TGF-β regulate fibroblast expression of S100A8

Growth factors, including fibroblast growth factor-2 (FGF-2) and transforming growth factor-beta (TGF-beta) regulate fibroblast function, differentiation and proliferation. S100A8 and S100A9 are members of the S100 family of Ca2+-binding proteins and are now accepted as markers of inflammation. They are expressed by keratinocytes and inflammatory cells in human/murine wounds and by appropriately activated macrophages, endothelial cells, epithelial cells and keratinocytes in vitro. In this study, regulation and expression of S100A8 and S100A9 were examined in fibroblasts. Endotoxin (LPS), interferon gamma (IFNgamma), tumour-necrosis factor (TNF) and TGF-beta did not induce the S100A8 gene in murine fibroblasts whereas FGF-2 induced mRNA maximally after 12 h. The FGF-2 response was strongly enhanced and prolonged by heparin. Interleukin-1beta (IL-1beta) alone, or in synergy with FGF-2/heparin strongly induced the gene in 3T3 fibroblasts. S100A9 mRNA was not induced under any condition. Induction of S100A8 in the absence of S100A9 was confirmed in primary fibroblasts. S100A8 mRNA induction by FGF-2 and IL-1beta was partially dependent on the mitogen-activated-protein-kinase pathway and dependent on new protein synthesis. FGF-2-responsive elements were distinct from the IL-1beta-responsive elements in the S100A8 gene promoter. FGF-2-/heparin-induced, but not IL-1beta-induced responses were significantly suppressed by TGF-beta, possibly mediated by decreased mRNA stability. S100A8 in activated fibroblasts was mainly intracytoplasmic. Rat dermal wounds contained numerous S100A8-positive fibroblast-like cells 2 and 4 days post injury; numbers declined by 7 days. Up-regulation of S100A8 by FGF-2/IL-1beta, down-regulation by TGF-beta, and its time-dependent expression in wound fibroblasts suggest a role in fibroblast differentiation at sites of inflammation and repair.

High nuclear S100A6 (Calcyclin) is significantly associated with poor survival in pancreatic cancer patients

Recent studies have reported elevated levels of S100A6 in pancreatic ductal adenocarcinoma cells. Here, we describe a detailed analysis of S100A6 expression in benign (n = 32), malignant (n = 60), and premalignant pancreatic ductal cells [96 pancreatic intraepithelial neoplasias (PanIN) from 46 patients]. S100A6 staining was more intense in malignant cells than in benign cells (P = 0.0001). In malignant cells, staining was higher in the nucleus than in the cytoplasm (P = 0.003). Univariate analysis revealed a significant decrease in survival time for patients with high levels of nuclear (P = 0.01) but not cytoplasmic (P = 0.20) S100A6. No evidence was found for an association between nuclear S100A6 expression and other variables, including gender, age at surgery, tumor size or grade, nodal metastases, resection margin, vascular invasion, perineural invasion, p53 or Smad4 levels (both linked to survival in previous studies), or the p65 subunit of nuclear factor-kappaB (a potential regulator of S100A6). Although nodal metastases and resection margin involvement were also associated with poor survival (P = 0.06 in both cases), multivariate analysis suggests that nuclear S100A6 is a significant independent indicator of survival (P = 0.003). Whereas PanIN 1a lesions showed a general absence of S100A6 staining, there was a progressive increase in the proportion of positively stained PanINs with increasing PanIN grade. In particular, we observed an increase in the frequency and intensity of nuclear staining. Our results suggest that up-regulation of S100A6 is an early event in pancreatic cancer development and that elevated levels of nuclear S100A6 may affect clinical outcome.

Autocrine activation of an osteopontin-CD44-Rac pathway enhances invasion and transformation by H-RasV12

Activated forms of Ras family members are prevalent in many cancers where Ras mutants transduce signals essential for transformation, angiogenesis, invasion and metastasis. As a cancer progression model, we used NIH3T3 cells to explore the mechanism of Ras-induced tumorigenesis. Ras family mutants H-RasV12 and Rit79L strongly induced foci formation, while Rho family mutants RhoA-QL, Rac1-QL and Cdc42-QL were less effective. A comparison of downstream transcriptional targets of Ras and Rho family members using a 26 383 element cDNA microarray revealed that the osteopontin (OPN) gene exhibited the best correlation between magnitude of gene expression change and level of foci formation (r=0.96, P<0.001). In association with H-RasV12- and Rit79L-mediated transformation, foci secreted OPN protein and upregulated the OPN receptor CD44, suggesting the novel initiation of an aberrant OPN-CD44-Rac autocrine pathway. In support of this were the following observations. First, RGD-deficient OPN protein-binding activity was present in H-RasV12-transformed cells but not in control cells, and binding activity was inhibited by the CD44 blocking antibody. Second, foci formation, cell invasion and Rac activity were induced by H-RasV12 and inhibited by the CD44 blocking antibody. Third, foci formation by H-RasV12 was substantially reduced by a short interfering RNA (siRNA) specifically targeting OPN expression for knockdown. Fourth, H-RasV12-mediated transformation was not blocked by the GRGDS peptide, suggesting that OPN effects were not mediated by the integrins. Lastly, OPN knockdown affected the downstream expression of 160 '2nd tier' genes, and at least a subset of these genes appears to be involved in transformation. Indeed, four genes were selected for knockdown, each resulting in a disruption of foci formation and/or invasion. These results underscore the role of aberrant autocrine signaling and transcriptional networking during tumorigenesis.

S100 proteins and their influence on pro-survival pathways in cancer

The S100 gene family is composed of at least 20 members that share a common structure defined in part by the Ca2+ binding EF-hand motif. These genes which are expressed in a discriminate fashion in specific cells and tissues, have been described to have either an intracellular or extracellular function, or both. S100 proteins are implicated in the immune response, differentiation, cytoskeleton dynamics, enzyme activity, Ca2+ homeostasis and growth. A potential role for S100 proteins in neoplasia stems from these activities and from the observation that several S100 proteins have altered levels of expression in different stages and types of cancer. While the precise role and importance of S100 proteins in the development and promotion of cancer is poorly understood, it appears that the binding of Ca2+ is essential for exposing amino acid residues that are important in forming protein-protein interactions with effector molecules. The identity of some of these effector molecules has also now begun to emerge, and with this the elucidation of the signaling pathways that are modulated by these proteins. Some of these interactions are consistent with the diverse functions noted above. Others suggest that, many S100s may also promote cancer progression through specific roles in cell survival and apoptosis pathways. This review summarizes these findings and their implications.

Transcriptional response of bronchial epithelial cells to Pseudomonas aeruginosa: identification of early mediators of host defense

The airway epithelium responds to microbial exposure by altering expression of a variety of genes to increase innate host defense. We aimed to delineate the early transcriptional response in human primary bronchial epithelial cells exposed for 6 h to a mixture of IL-1beta and TNF-alpha or heat-inactivated Pseudomonas aeruginosa. Because molecular mechanisms of epithelial innate host defense are not fully understood, the open-ended expression-profiling technique SAGE was applied to construct gene expression profiles covering 30,000 genes: 292 genes were found to be differentially expressed. Expression of seven genes was confirmed by real-time qPCR. Among differentially expressed genes, four classes or families were identified: keratins, proteinase inhibitors, S100 calcium-binding proteins, and IL-1 family members. Marked transcriptional changes were observed for keratins that form a key component of the cytoskeleton in epithelial cells. Expression of antimicrobial proteinase inhibitors SLPI and elafin was elevated after microbial or cytokine exposure. Interestingly, expression of numerous S100 family members was observed, and eight members, including S100A8 and S100A9, were among the most differentially expressed genes. Differential expression was also observed for the IL-1 family members IL-1beta, IL-1 receptor antagonist, and IL-1F9, a newly discovered IL-1 family member. Clustering of differentially expressed genes into biological processes revealed that the early inflammatory response in airway epithelial cells to IL-1beta-TNF-alpha and P. aeruginosa is characterized by expression of genes involved in epithelial barrier formation and host defense.

Astrocytic calcium/zinc binding protein S100A6 over expression in Alzheimer's disease and in PS1/APP transgenic mice models

Astrocytes recruitment and activation are a hallmark of many neurodegenerative diseases including Alzheimer's disease (AD). We have previously observed an overexpression for S100A6 protein, a Ca(2+)/Zn(2+) binding protein presenting more affinity for zinc than for calcium, in amyotrophic lateral sclerosis (ALS). Here we demonstrated in AD patients but also in two different AD mouse models, that astrocytic S100A6 protein was homogeneously up-regulated within the white matter. However, within the grey matter, almost all S100A6 immunoreactivity was concentrated in astrocytes surrounding the Abeta amyloid deposits of senile plaques. These S100A6 neocortex labelled astrocytes were also positive for the glial fibrillary acidic protein (GFAP) and S100B protein. Contrasting with S100A6, the distribution for S100B and GFA astrocytic labelled cells was not restricted to the Abeta amyloid deposit in grey matter, but widely distributed throughout the neocortex. Coupling the knowledge that biometals such as zinc are highly concentrated in the amyloid deposits in AD and S100A6 having a high affinity for Zn(2+) may suggest that S100A6 plays a role in AD neuropathology.

Calcyclin (S100A6) expression is stimulated by agents evoking oxidative stress via the antioxidant response element

Calcyclin (S100A6) is a cell-specific, calcium binding protein of the S100 family whose expression is augmented in many types of cancer. By means of luciferase activity assays, RT-PCR and Northern blot hybridization, we established that transcription of S100A6 gene is increased by agents known to evoke oxidative stress. Mutation of the antioxidant response element (ARE) located at position -290/-281 of the calcyclin gene promoter, and overlapping the E-box sequence recognized by the upstream stimulatory factor (USF), led to inhibition of calcyclin gene promoter activity stimulated by cadmium ions. Electrophoretic mobility shift assays (EMSA) with the -302/-260 calcyclin gene promoter fragment revealed, apart from USF binding, the presence of another protein complex (N) shown by competitive EMSA to be bound to ARE. DNA affinity chromatography followed by Western blot showed the binding of Nrf2 transcription factor to the immobilized calcyclin gene promoter fragment and concomitant appearance of complex N in EMSA of the eluted fractions. The results indicate that agents evoking oxidative stress activate calcyclin gene via the ARE sequence in its promoter.

Identification of differentially expressed genes in scrapie-infected mouse brains by using global gene expression technology

The pathogenesis of prion diseases, a class of transmissible fatal neurodegenerative diseases in humans and animals, is still unclear. The aim of this study was to identify the differentially regulated genes that correlate with the development of prion diseases for a better understanding of their pathological mechanisms. We employed Affymetrix Mouse Expression Arrays 430A containing >22,000 transcripts and compared the global gene expression profiles from brains of mice who were intracerebrally inoculated with scrapie strains ME7 and RML with those from brains of uninfected and mock-infected mice. The microarray data were analyzed by Significance Analysis of Microarrays, revealing 121 genes whose expression increased at least twofold in both ME7- and RML-infected mouse brains, with an estimated false discovery rate of < or =5%. These genes encode proteins involved in proteolysis, protease inhibition, cell growth and maintenance, the immune response, signal transduction, cell adhesion, and molecular metabolism. The time course of expression generally showed up-regulation of these genes from 120 days postinoculation (dpi) for ME7-inoculated mouse brains and from 90 dpi for RML-inoculated mouse brains. The onset of elevated expression correlated temporally with the onset of PrP(Sc) accumulation and the activation of glia, which may have contributed to neuronal cell death. Among the differentially regulated genes reported in the present study, the emergence of genes for several cathepsins and S100 calcium binding proteins was conspicuous. These and other genes reported here may represent novel potential diagnostic and therapeutic targets for prion disease.

Dissection of the mammalian midbody proteome reveals conserved cytokinesis mechanisms

Cytokinesis is the essential process that partitions cellular contents into daughter cells. To identify and characterize cytokinesis proteins rapidly, we used a functional proteomic and comparative genomic strategy. Midbodies were isolated from mammalian cells, proteins were identified by multidimensional protein identification technology (MudPIT), and protein function was assessed in Caenorhabditis elegans. Of 172 homologs disrupted by RNA interference, 58% displayed defects in cleavage furrow formation or completion, or germline cytokinesis. Functional dissection of the midbody demonstrated the importance of lipid rafts and vesicle trafficking pathways in cytokinesis, and the utilization of common membrane cytoskeletal components in diverse morphogenetic events in the cleavage furrow, the germline, and neurons.

Involvement of NF-kappaB in the regulation of S100A6 gene expression in human hepatoblastoma cell line HepG2

S100A6 (calcyclin) is an acidic calcium binding protein with two EF-hand motifs and overexpressed in several tumors including intrahepatic carcinoma. TNFalpha, a strong NF-kappaB activator required for hepatocyte proliferation during liver regeneration, triggered the expression of S100A6 mRNA in human hepatoblastoma cell line HepG2. Transient expression of NF-kappaB (p65) increased S100A6 promoter activity and expression of inhibitor of NF-kappaB (IkappaBalpha) decreased TNFalpha-induced S100A6 promoter activity. To confirm the involvement of NF-kappaB in S100A6 promoter activation, we analyzed serially deleted promoter constructs of the S100A6 gene by luciferase reporter assay and found a NF-kappaB-responsive DNA fragment at the position between -584 and -361. Electrophoretic mobility shift assays showed that TNFalpha induced p65 binding to a potential NF-kappaB binding site at -460/-451. Furthermore, treatment of cells with CAPE (caffeic acid phenethyl ester), a specific NF-kappaB (p65) inhibitor, decreased NF-kappaB binding and promoter activity. These results suggest that NF-kappaB transcription factor contributes to the activation of S100A6 gene expression in response to TNFalpha in HepG2 cells.