Loss of nuclear localization of the S100C protein in immortalized human fibroblasts

The Calcium Binding Protein S100A11 and Its Roles in Diseases

The calcium binding protein S100 family in humans contains 21 known members, with each possessing a molecular weight between 10 and 14 kDa. These proteins are characterized by a unique helix-loop-helix EF hand motif, and often form dimers and multimers. The S100 family mainly exists in vertebrates and exerts its biological functions both inside cells as a calcium sensor/binding protein, as well as outside cells. S100A11, a member of the S100 family, may mediate signal transduction in response to internal or external stimuli and it plays various roles in different diseases such as cancers, metabolic disease, neurological diseases, and vascular calcification. In addition, it can function as chemotactic agent in inflammatory disease. In this review, we first detail the discovery of S100 proteins and their structural features, and then specifically focus on the tissue and organ expression of S100A11. We also summarize its biological activities and roles in different disease and signaling pathways, providing an overview of S100A11 research thus far.

Colorectal cancer progression correlates with upregulation of S100A11 expression in tumor tissues

BACKGROUND AND AIMS

Early detection and treatment of human colorectal cancers remain a challenge. Identification of new potential markers may help in the diagnosis of colorectal cancer.

MATERIALS AND METHODS

By comparative two-dimensional gel electrophoresis using extracts from colorectal tumor and adjacent normal tissues, we identified a calcium-binding protein, S100A11, which was highly expressed in colorectal cancer compared with adjacent normal tissues. We expanded our study in 89 clinical colorectal tumor samples to validate this finding and correlates S100A11 expression in human colorectal cancer tissues with various stages of the tumor by Western blotting and immunohistochemical staining.

RESULTS

We identified a calcium-binding protein, S100A11, which was highly expressed in colorectal cancer compared with adjacent normal tissues. S100A protein was expressed predominantly in the cytoplasm of normal tissue; however, it was expressed in both the nuclei and cytoplasm of colorectal cancer. S100A11 level in colorectal cancer tissue was increased following stage progression of the disease.

CONCLUSION

These findings suggest S100A11 could be helpful in the pathological study of colorectal cancer, especially for the classification of different stages in colorectal cancer.

Global Protein Shotgun Expression Profiling of Proliferating MCF-7 Breast Cancer Cells

Protein expression becomes altered in breast epithelium during malignant transformation. Knowledge of these perturbations should provide insight into the molecular basis of breast cancer, as well as reveal possible new therapeutic targets. To this end, we have performed an extensive comparative proteomic survey of global protein expression patterns in proliferating MCF-7 breast cancer cells and normal human mammary epithelial cells using gel-free shotgun tandem mass spectrometry. Pathophysiological alterations associated with the malignant breast cancer phenotype were detected, including differences in the apparent levels of key regulators of the cell cycle, signal transduction, apoptosis, transcriptional regulation, and cell metabolism.

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.

Down-Regulation of S100C Is Associated with Bladder Cancer Progression and Poor Survival

Purpose: The goal of this study was to identify proteins down-regulated during bladder cancer progression.

Experimental design: By using comparative proteome analysis and measurement of mRNA, we found a significant down-regulation of S100C, a member of the S100 family of proteins, in T24 (grade 3) as compared with RT4 (grade 1) bladder cancer cell lines. Moreover, quantification of the mRNA level revealed that decreased expression of the protein reflects a low level of transcription of the S100C gene. Based on this observation, we quantified the S100C mRNA expression level with real-time PCR in bladder cancer biopsy samples obtained from 88 patients followed for a median of 23 months (range, 1-97 months).

Results: We found a significantly lower mRNA expression of S100C in connective tissue invasive tumors (T1, P = 0.0030) and muscle invasive tumors [(T2-T4), P < 0.0001] compared with superficial tumors (Ta). A negative correlation between S100C and histopathologic grade (P = 0.0003) was also observed. Furthermore, the papillary type showed higher expression of S100C than did the solid type of the tumor (P < 0.0001). Importantly, we found that loss of S100C was associated with survival in bladder cancer patients (P = 0.0006).

Conclusions: Our results show that low expression of S100C is associated with poor survival in patients with bladder cancer. Furthermore, loss of S100C in T1 as compared with Ta stage tumors emphasize that S100C expression is suppressed early during bladder cancer development.

Matricellular protein SPARC is translocated to the nuclei of immortalized murine lens epithelial cells

The matricellular glycoprotein, secreted protein acidic and rich in cysteine (SPARC), has complex biological activities and is important for lens epithelial cell function and regulation of cataract formation. To understand how SPARC influences lens epithelial cell activity and homeostasis, we have studied the subcellular distribution of SPARC in murine lens epithelial cells in vitro. We demonstrate that endogenous SPARC is located in the cytoplasm of either quiescent or dividing lens epithelial cells in culture. However, cytoplasmic SPARC was translocated into the nuclei of immortalized lens epithelial cells upon a significant reduction of intracellular SPARC in these cells. Recombinant human (rh) SPARC added to the culture media was quickly and efficiently internalized into the cytosol of SPARC-null lens epithelial cells. Moreover, cytoplasmic rhSPARC was also translocated into the nucleus after exogenous rhSPARC was removed from the culture media. The translocation of SPARC into the nucleus was therefore triggered by the reduction of SPARC protein normally available to the cells. A mouse SPARC-EGFP chimeric fusion protein (70 kDa) was expressed in lens epithelial cells and 293-EBNA cells, and was observed both in the cytoplasm and culture medium, but not in the nucleus. SPARC does not appear to have a strong nuclear localization sequence. Alternatively, SPARC might pass through the nuclear pore complex by passive diffusion. SPARC therefore functions not only as an extracellular protein but also potentially as an intracellular protein to influence cellular activities and homeostasis.

Differential expression of S100C in thyroid lesions

Identification of new potential markers that may help in the diagnosis of benign and malignant thyroid lesions is needed. By comparative 2-dimensional gel electrophoresis of microdissected cells from tumors and normal thyroid tissue, we identified a new protein, S100C, which is highly expressed in papillary carcinomas. In order to validate this finding, we investigated the immunohistochemical expression and the potential role in diagnosis of these markers in 94 specimens representing the spectrum of malignant and benign thyroid lesions. Normal thyroid tissue was evaluated in 57 specimens. Galectin-3, a marker reported as specific for malignant lesions, was also evaluated in the same lesions. S100C protein was expressed in the nuclei of normal tissue, hyperplastic nodules, and follicular adenomas and carcinomas. Papillary carcinomas showed a strong, but cytoplasmic, pattern of staining. Galectin-3 immunostaining was strongly positive in papillary carcinomas, and negative in benign lesions, confirming its value in differential diagnosis. These findings suggest that immunohistochemical staining of S100C could be helpful in the pathological study of thyroid lesions, especially in cases in which follicular variants of papillary carcinoma and follicular carcinoma are considered in the differential diagnosis.

Dysregulated expression of S100A11 (calgizzarin) in prostate cancer and precursor lesions

S100A11 is a calcium-binding protein implicated in a variety of biologic functions such as proliferation and differentiation as well as in cancer. To further understand its role in prostate cancer, we performed immunohistochemistry on a series of benign, premalignant, malignant and metastatic prostate cancer tissues in addition to prostate cancer derived cell lines. In benign prostatic hyperplasia (n=30) and benign tissue adjacent to adenocarcinoma (n=54), S100A11 expression was significantly higher in basal cells compared with in luminal cells (P <0.001). A complete absence of staining was seen in 4/14 (29%) lesions of prostatic intraepithelial neoplasia. The majority of tumors, 39/54 (72%), showed significant overexpression of S100A11 compared with the luminal cells of adjacent benign epithelium (P <0.001), whereas 14/54 (26%) of cases showed an absence of staining. All 4 cases of metastatic cancer showed intense to moderate expression. There was a significant association between S100A11 expression and high pathologic stage (pT3b) versus lower stages (pT2a-3a; P=0.027), but not with tumor Gleason score or prostate-specific antigen levels. LNCaP, PC3, and Du145 cancer cell lines showed intense to moderate S100A11 expression by immunochemistry, which was confirmed by Western blotting and reverse-transcription polymerase chain reaction. A survey of 14 other types of normal tissues arranged on a tissue microarray showed that S100A11 is widely expressed amongst epithelia. Our finding of frequent dysregulated expression of S100A11 in cancer and precursor lesions, together with an association with high histological stage, suggests that S100A11 may be involved in prostate cancer development and progression.

Establishment of an immortalized human-liver endothelial cell line with SV40T and hTERT

BACKGROUND AND AIMS

Liver endothelial cells (LECs) perform an essential role in important pathophysiologic functions in the liver. Establishment of a human LEC line facilitates advances in LEC research. Here, we present immortalization of human LECs using retroviral gene transfer of simian virus 40 large T antigen (SV40T) and human telomerase reverse transcriptase (hTERT). We also demonstrate excision of SV40T and hTERT with TAT-mediated Cre/loxP recombination and subsequent cell sorting.

METHODS

First, human LECs were transduced with a retroviral vector somatostatin receptor (SSR)#69 expressing SV40T and hygromycin-resistance genes flanked by a pair of loxA recombination targets. Then, cells were retrovirally superinfected with SSR#197 encoding hTERT and green fluorescent protein (GFP) cDNAs that were intervened by two loxBs. One SV40T-and hTERT-immortalized LEC clone, TMNK-1, was established and analyzed for its biologic characteristics.

RESULTS

The cells were hygromycin-resistant and uniformly positive for GFP expression. TMNK-1 expressed EC markers, including factor VIII, vascular endothelial growth factor receptors (flt-1, KDR/Flk-1), and CD34, showed uptake of Di-I-acetylated-low-density lipoprotein and angiogenic potential in Matrigel assays. After lipopolysaccharide treatment, TMNK-1 produced tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 and exhibited increased expression of intra-cellular adhesive molecule-1, vascular cellular adhesive molecule-1, and VE-cadherin. After treatment with TAT-Cre recombinase fusion protein, approximately 60% of TMNK-1 was negative for GFP expression, and subsequent cell sorting of this population for GFP allowed for collection of the reverted form of TMNK-1.

CONCLUSIONS

This study demonstrates the utility and efficiency of the reversible immortalization procedure to expand primary human LECs for basic studies.

Transforming Growth Factor-β1 Specifically Induce Proteins Involved in the Myofibroblast Contractile Apparatus

Transforming growth factor-beta(1) (TGF-beta(1)) induces alpha-smooth muscle actin (alpha-SMA) and collagen synthesis in fibroblast both in vivo and in vitro and plays a significant role in tissue repair and the development of fibrosis. During these processes the fibroblasts differentiate into activated fibroblasts (so called myofibroblasts), characterized by increased alpha-SMA expression. Because TGF-beta(1) is considered the main inducer of the myofibroblast phenotype and cytoskeletal changes accompany this differentiation, the main objective of this investigation was to study how TGF-beta(1) alters protein expression of cytoskeletal-associated proteins. Metabolic labeling of cell cultures by [(35)S]methionine, followed by protein separation on two-dimensional gel electrophoresis, displayed approximately 2500 proteins in the pI interval of 3-10. Treatment of TGF-beta(1) led to specific spot pattern changes that were identified by mass spectrometry and represent specific induction of several members of the contractile apparatus such as calgizzarin, cofilin, and profilin. These proteins have not previously been shown to be regulated by TGF-beta(1), and the functional role of these proteins is to participate in the depolymerization and stabilization of the microfilaments. These results show that TGF-beta(1) induces not only alpha-SMA but a whole set of actin-associated proteins that may contribute to the increased contractile properties of the myofibroblast. These proteins accompany the induced expression of alpha-SMA and may participate in the formation of stress fibers, cell contractility, and cell spreading characterizing the myofibroblasts phenotype.

S100 protein translocation in response to extracellular S100 is mediated by receptor for advanced glycation endproducts in human endothelial cells

The extracellular functions of S100 proteins have attracted more attention in recent years. S100 proteins are a group of calcium-binding proteins which exhibit cell- and tissue-specific expression, and different expression levels of members from this family have been observed in various pathological conditions. The reported extracellular functions of S100 proteins include the ability to enhance neurite outgrowth, involvement in inflammation, and motility of tumour cells. In our previous study, we reported translocation of S100A13 in response to the elevated intracellular calcium levels induced by angiotensin II. In order to investigate potential effects of extracellular S100A13, recombinant S100A13 was used here to stimulate human endothelial cells. Addition of extracellular S100A13 to the cells resulted in both endogenous protein translocation and protein uptake from the extracellular space. To test specificity of this effect, addition of various other S100 proteins was also performed. Interestingly, translocation of specific S100 proteins was only observed when the cells were stimulated with the same extracellular S100 protein. Since the receptor for advanced glycation end products (RAGE) is a putative cell surface receptor for S100 proteins and is involved in various signal transduction pathways, we next investigated the interaction between the receptor and extracellular S100 proteins. We show here that NF-kappaB which is a downstream regulator in RAGE-mediated transduction pathways can be activated by addition of extracellular S100 proteins, and translocation of S100 proteins was inhibited by soluble RAGE. These experiments suggest a common cell surface receptor for S100 proteins on endothelial cells even though intracellular translocation induced by extracellular S100 proteins is specific.

Up-regulation of S100C in normal human fibroblasts in the process of aging in vitro

S100 proteins belonging to the EF-hand Ca(2+)-binding protein family regulate a variety of cellular processes via interaction with different target proteins. Several diseases, including cancer and Alzheimer's disease, are related to a disorder of multifunctional S100 proteins, which are expressed in cell- and tissue-specific manners. We previously demonstrated that S100C could move to and accumulate in the nuclei of normal human fibroblasts but not in the nuclei of immortalized and neoplastic cells. In addition, we found that its nuclear accumulation resulted in suppression of DNA synthesis in normal cells at a confluent stage. In the present study, we investigated whether S100C was associated with cellular senescence in vitro. We found that S100C expression increased in normal human fibroblasts in the process of aging in culture and was accompanied by accumulation of its protein in the nuclei of senescent fibroblasts. In addition, the nuclear accumulation of S100C increased expression of a cyclin-dependent kinase inhibitor p21(Sdi1), a strong inhibitor of cell growth. These findings suggest that an increase in the cells having nuclear accumulation of S100C is closely related to the process of cellular senescence of normal human fibroblasts.