Calcium-binding protein S100A4 in health and disease

S-100 Proteins: Basics and Applications as Biomarkers in Animals with Special Focus on Calgranulins (S100A8, A9, and A12)

S100 proteins are a group of calcium-binding proteins which received this name because of their solubility in a 100% saturated solution of ammonium sulphate. They have a similar molecular mass of 10-12 KDa and share 25-65% similarity in their amino acid sequence. They are expressed in many tissues, and to date 25 different types of S100 proteins have been identified. This review aims to provide updated information about S100 proteins and their use as biomarkers in veterinary science, with special emphasis on the family of calgranulins that includes S100A8 (calgranulin A; myeloid-related protein 8, MRP8), S100A9 (calgranulin B; MRP14), and S100A12 (calgranulin C). The proteins SA100A8 and S100A9 can be linked, forming a heterodimer which is known as calprotectin. Calgranulins are related to the activation of inflammation and the immune system and increase in gastrointestinal diseases, inflammation and sepsis, immunomediated diseases, and obesity and endocrine disorders in different animal species. This review reflects the current knowledge about calgranulins in veterinary science, which should increase in the future to clarify their role in different diseases and potential as biomarkers and therapeutic targets, as well as the practical use of their measurement in non-invasive samples such as saliva or feces.

Tandem mass tag labeling to assess proteome differences between intermediate and very tender beef steaks

Tenderness is considered as one of the most important quality attributes dictating consumers' overall satisfaction and future purchasing decisions of fresh beef. However, the ability to predict and manage tenderness has proven very challenging due to the numerous factors that contribute to variation in end-product tenderness. Proteomic profiling allows for global examination of differentially abundant proteins in the meat and can provide new insight into biological mechanisms related to meat tenderness. Hence, the objective of this study was to examine proteomic profiles of beef longissimus lumborum (LL) steaks varying in tenderness, with the intention to identify potential biomarkers related to tenderness. For this purpose, beef LL muscle samples were collected from 99 carcasses at 0 and 384 h postmortem. Based on Warner-Bratzler shear force values at 384 h, 16 samples with the highest (intermediate tender, IT) and lowest (very tender, VT) values were selected to be used for proteomic analysis in this study (n = 8 per category). Using tandem mass tag-based proteomics, a total of 876 proteins were identified, of which 51 proteins were differentially abundant (P < 0.05) between the tenderness categories and aging periods. The differentially identified proteins encompassed a wide array of biological processes related to muscle contraction, calcium signaling, metabolism, extracellular matrix organization, chaperone, and apoptosis. A greater (P < 0.05) relative abundance of proteins associated with carbohydrate metabolism and apoptosis, and a lower (P < 0.05) relative abundance of proteins involved in muscle contraction was observed in the VT steaks after aging compared with the IT steaks, suggesting that more proteolysis occurred in the VT steaks. This may be explained by the greater (P < 0.05) abundance of chaperonin and calcium-binding proteins in the IT steaks, which could have limited the extent of postmortem proteolysis in these steaks. In addition, a greater (P < 0.05) abundance of connective tissue proteins was also observed in the IT steaks, which likely contributed to the difference in tenderness due to added background toughness. The established proteomic database obtained in this study may provide a reference for future research regarding potential protein biomarkers that are associated with meat tenderness.

Role of fibroblast specific protein 1 expression in the progression of adriamycin-induced glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a commonly occurring cause of steroid-resistant nephrotic syndrome and frequently progresses to renal failure. Podocyte epithelial-mesenchymal transition (EMT) is thought to induce podocyte detachment in glomerular diseases, and severe degeneration and shedding of glomerular podocytes plays a major role in the progression of FSGS. We showed that fibroblast specific protein 1 (FSP1), an EMT marker, is strongly expressed in podocytes of FSGS patients, but the significance of podocyte expression of FSP1 to the pathophysiology of FSGS remained unclear. Here, we investigated FSP1 expression in podocytes from mice with adriamycin (ADR)-induced nephropathy, a murine model of FSGS. The number of FSP1-positive (FSP1+) podocytes was increased in ADR-treated mice and positively correlated with the degree of proteinuria and glomerulosclerosis in ADR-treated mice. ADR-induced FSGS and the attendant proteinuria were significantly ameliorated in FSP1 knockout mice as compared to wild type mice. These findings indicate that podocyte expression of FSP1 plays a crucial role in the pathogenesis of FSGS, which makes FSP1 a potential target for treatment of FSGS.

S100A4 plays a key role in TRPV3 ion channel expression and its electrophysiological function

Transient receptor potential vanilloid 3 (TRPV3), a non-selective cation ion channel, is regulated by small molecules such as Ca²⁺ and calmodulin (CaM). Together with S100A4 (S100 calcium-binding protein family), is critical in cell proliferation and progression. Although TRPV3 has been proved to play a role in Ca²⁺ regulation and participate in Ca²⁺-related cellular processes, its molecular mechanism remains unclear. In this study, we found that TRPV3 and S100A4 were co-expressed in the same region of the cell, and surprisingly, the protein expression level of TRPV3 significantly increased with the overexpression of S100A4. Moreover, co-immunoprecipitation results showed that these two proteins could bind with each other. Functionally, we found that when S100A4 was simultaneously expressed in cells, more Ca²⁺ would be transferred into the cells through the TRPV3 ion channel. Consistent with Ca²⁺ regulation results, electrophysiological recordings demonstrated that S100A4 improved the function of TRPV3 in ions' flux, suggesting that the S100A4 could bind with TRPV3 and simultaneously promoted its expression, thus affecting its functions on related ions' flux. Our findings identified the link between S100A4 and TRPV3 and provided a novel molecular mechanism for TRPV3 regulation.

Plasma S100A4 level and cardiovascular risk in patients with unstable angina pectoris

Aim: We investigated whether S100A4 level is associated with pathophysiology of unstable angina pectoris (UAP), and its potential prognostic value for subsequent cardiovascular events. Methods: We compared plasma levels of S100A4 and a set of clinical markers in three groups (59 with UAP, 32 with stable angina pectoris and 30 healthy controls). Results: S100A4 levels in patients with UAP were significantly elevated. In UAP group, baseline S100A4 levels were significantly higher in patients with subsequent cardiovascular events than those without, a positive correlation was identified between the risk of subsequent cardiovascular events and the plasma levels of S100A4. Conclusion: Elevated S100A4 levels may be involved in the pathogenesis of UAP, and may be a marker predictive of post-treatment cardiovascular events.

Expression profile and functional role of S100A14 in human cancer

S100A14 is one of the new members of the multi-functional S100 protein family. Expression of S100A14 is highly heterogeneous among normal human tissues, suggesting that the regulation of S100A14 expression and its function may be tissue- and context-specific. Compared to the normal counterparts, S100A14 mRNA and protein levels have been found to be deregulated in several cancer types, indicating a functional link between S100A14 and malignancies. Accordingly, S100A14 is functionally linked with a number of key signaling molecules such as p53, p21, MMP1, MMP9, MMP13, RAGE, NF-kB, JunB, actin and HER2. Of interest, S100A14 seems to have seemingly opposite functions in malignancies arising from the gastrointestional tract (tissues rich in epithelial components) compared to cancers in the other parts of the body (tissues rich in mesenchymal components). The underlying mechanism for these observations are currently unclear and may be related to the relative abundance and differences in the type of interaction partners (effector protein) in different cancer types and tissues. In addition, several studies indicate that the expression pattern of S100A14 has a potential to be clinically useful as prognostic biomarker in several cancer types. This review attempts to provide a comprehensive summary on the expression pattern and functional roles/related molecular pathways in different cancer types. Additionally, the prognostic potential of S100A14 in the management of human malignancies will be discussed.

A review of S100 protein family in lung cancer

S100 protein family, representing 25 relatively small calcium binding proteins, has been reported to be involved in multiple stages of tumorigenesis and progression. These proteins are considered having potential value to be adopted as novel biomarkers in the detection and accurate prediction of many kinds of tumors, including lung cancer. As the one having the highest morbidity and mortality among all cancers, lung carcinoma is still occult for detection, especially at early stage. S100 proteins take participation in the lung neoplasia through playing intracellular and/or extracellular functions, therefore getting involved in a variety of biological processes such as differentiation, proliferation, and migration. A few members have also been testified to modulate TGF-β/Smad-3 mediated transcriptional activity of target genes involved in tumor promotion. In addition to that, a number of proteins in this family have already been reported to experience an abnormal trend in lung cancer at cell, serum and tissue levels. Thus, S100 proteins may serve as effective biomarkers for suspected or already diagnosed lung cancer patients. In future, S100 protein family might be applied as therapeutic targets in clinical treatment of lung cancer. In this review, we firstly summed up the biological and clinical evidence connecting S100 proteins and lung cancer, which has not been summarized before.

Immunohistochemical Localization of Epithelial Mesenchymal Transition Markers in Cyclosporine A Induced Gingival Overgrowth

INTRODUCTION

Cyclosporine, an immunosuppressive agent used in the management of renal transplant patients is known to produce Drug Induced Gingival Overgrowth (DIGO) as a side effect. Several mechanisms have been elucidated to understand the pathogenesis of DIGO. Recently, epithelial mesenchymal transition has been proposed as a mechanism underlying fibrosis of various organs.

AIM

The aim of the study was to investigate if Epithelial Mesenchymal Transition (EMT) operates in Cyclosporine induced gingival overgrowth.

MATERIALS AND METHODS

The study involved obtaining gingival tissue samples from healthy individuals (n=17) and subjects who exhibited cyclosporine induced gingival overgrowth (n=18). Presence and distribution of E-Cadherin, S100 A4 and alpha smooth muscle actin (α-SMA) was assessed using immunohistochemistry and cell types involved in their expression were determined. The number of α- SMA positive fibroblasts were counted in the samples.

RESULTS

In control group, there was no loss of E-Cadherin and a pronounced staining was seen in the all layers of the epithelium in all the samples analysed (100%). S100 A4 staining was noted in langerhans cells, fibroblasts, endothelial cells and endothelial lined blood capillaries in Connective Tissue (CT) of all the samples (100%) while α - SMA staining was seen only on the endothelial lined blood capillaries in all the samples (100%). However in DIGO, there was positive staining of E-Cadherin only in the basal and suprabasal layers of the epithelium in all the samples (100%). Moreover there was focal loss of E-Cadherin in the epithelium in eight out of 18 samples (44%). A break in the continuity of the basement membrane was noted in three out of 18 samples (16%) on H & E staining.

CONCLUSION

Based on the analysis of differential staining of the markers, it can be concluded that EMT could be one of the mechanistic pathways underlying the pathogenesis of DIGO.

Fibroblasts and Mesenchymal Stromal/Stem Cells Are Phenotypically Indistinguishable

BACKGROUND/AIMS

Human mesenchymal stromal/stem cells (MSCs), derived from many different tissues, are characterized by a fibroblast-like morphology, the expression of certain cell surface markers and their ability to differentiate into adipocytes, chondrocytes and osteoblasts. A number of studies have shown that MSCs share many characteristics with fibroblasts; however, there is no well-defined set of phenotypic characteristics that could distinguish between these 2 types of cells.

METHODS

We used 4 well-established human fibroblast strains from 3 different tissue sources and several human MSC strains from 2 different tissue sources to compare the phenotypic and immunological characteristics of these cells.

RESULTS

Fibroblast strains had a similar morphology to MSCs, expressed the same cell surface markers as MSCs and could also differentiate into adipocytes, chondrocytes and osteoblasts. Also, similar to MSCs, these fibroblasts were capable of suppressing T cell proliferation and modulating the immunophenotype of macrophages. We also show that MSCs deposit extracellular matrices of collagen type I and fibronectin, and express FSP1 in patterns similar to fibroblasts.

CONCLUSIONS

Based on currently accepted definitions for cultured human MSCs and fibroblasts, we could not find any immunophenotypic property that could make a characteristic distinction between MSCs and fibroblasts.

Localization of Nitric Oxide Synthase-containing Neurons in the Bat Visual Cortex and Co-localization with Calcium-binding Proteins

Microchiroptera (microbats) is a suborder of bats thought to have degenerated vision. However, many recent studies have shown that they have visual ability. In this study, we labeled neuronal nitric oxide synthase (nNOS)-the synthesizing enzyme of the gaseous non-synaptic neurotransmitter nitric oxide-and co-localized it with calbindin D28K (CB), calretinin (CR), and parvalbumin (PV) in the visual cortex of the greater horseshoe bat (Rhinolophus ferrumequinum, a species of microbats). nNOS-immunoreactive (IR) neurons were found in all layers of the visual cortex. Intensely labeled neurons were most common in layer IV, and weakly labeled neurons were most common in layer VI. Majority of the nNOS-IR neurons were round- or oval-type neurons; no pyramidal-type neurons were found. None of these neurons co-localized with CB, CR, or PV. However, the synthesis of nitric oxide in the bat visual cortex by nNOS does not depend on CB, CR, or PV.

Parvalbumin-immunoreactive cells in the superior colliculus in dog: distribution, colocalization with GABA, and effect of monocular enucleation

Parvalbumin (PV) is thought to play a major role in buffering intracellular calcium. We studied the distribution, morphology of PV-immunoreactive (IR) cells, and the effect of enucleation on the PV distribution in the superior colliculus (SC) in dog (Canis familiaris) and compared PV labeling to that of calbindin D28K (CB) and GABA. These cells formed three laminar tiers in the dog SC; 1) the upper superficial gray layer (SGL), 2) the lower optic layer (OL) and the upper intermediate gray layer, and 3) the deep layer. The third tier was not very distinct when compared with the other two tiers. The distribution of PV-IR cells is thus complementary to that of CB-IR tiers. Our present data on the distribution of PV-IR cells within the superficial layers are strikingly different from those in previously studied mammals, which show PV-IR cells within the lower SGL and upper OL. However, there were no distinct differences in distribution within the deep layers compared with that of previously studied mammals. PV-IR cells in the SC varied dramatically in morphology and size, and included round/oval, vertical fusiform, stellate, horizontal and pyriform cells. Two-color immunofluorescence revealed quantitatively that 11.67% of the PV-IR cells colocalized with GABA. Monocular enucleation appeared to have no effect on the distribution of PV-IR cells in the contralateral SC. Similar to CB, these data suggest that retinal projection may not control the expression of PV in the dog SC. These results provide important information for delineating similarities and differences in the neurochemical architecture of the visual system.

Immunocytochemical Localization of Calbindin D28K, Calretinin, and Parvalbumin in Bat Superior Colliculus

The purpose of this study was to investigate the localization of cells containing the calcium-binding proteins (CBPs) calbindin D28K (CB), calretinin (CR), and parvalbumin (PV) in the superior colliculus (SC) of the bat using immunocytochemistry. CB-immunoreactive (IR) cells formed a laminar tier within the upper superficial gray layer (SGL), while CR-IR cells were widely distributed within the optic layer (OL). Scattered CR-IR cells were also found within the intermediate gray, white, and deep gray layers. By contrast, PV-IR cells formed a laminar tier within the lower SGL and upper OL. Scattered PV-IR cells were also found throughout the intermediate layers, but without a specific laminar pattern. The CBP-IR cells varied in size and morphology: While most of the CB-IR cells in the superficial layers were small round or oval cells, most CR-IR cells in the intermediate and deep layers were large stellate cells. By contrast, PV-IR cells were small to large in size and included round or oval, stellate, vertical fusiform, and horizontal cells. The average diameters of the CB-, CR-, and PV-IR cells were 11.59, 17.17, and 12.60 μm, respectively. Double-immunofluorescence revealed that the percentage of co-localization with GABA-IR cells was 0.0, 0.0, and 10.27% of CB-, CR-, and PV-IR cells, respectively. These results indicate that CBP distribution patterns in the bat SC are unique compared with other mammalian SCs, which suggest functional diversity of these proteins in visually guided behaviors.

Silencing of S100A4, a metastasis-associated protein, in endothelial cells inhibits tumor angiogenesis and growth

Endothelial cells express S100A4, a metastasis-associated protein, but its role in angiogenesis remains to be elucidated. Here we show that knockdown of S100A4 in mouse endothelial MSS31 cells by murine specific small interference RNA (mS100A4 siRNA) markedly suppressed capillary-like tube formation in vitro, in early stage after the treatment, along with down- and up-regulation of some of the pro-angiogenic and anti-angiogenic gene expression, respectively. Of particular note is that intra-tumor administration of the mS100A4 siRNA in a human prostate cancer xenograft significantly reduced tumor vascularity and resulted in the inhibition of tumor growth. These findings show that S100A4 in endothelial cells is involved in tube formation, and suggest its potential as a molecular target for inhibiting tumor angiogenesis, which warrants further development of endothelial S100A4-based strategies for cancer treatment.

Systemic shRNA mediated knock down of S100A4 in colorectal cancer xenografted mice reduces metastasis formation

The metastasis-inducing protein S100A4 was found to be a prognostic indicator for the development of metachronous metastases. S100A4 expression levels correlate with the formation of human colorectal cancer metastases and shorter patients’ survival. Inhibition of S100A4 expression in patients might therefore result in decreased metastasis formation and prolonged survival. In the present study, we used shRNA expression plasmids to inhibit S100A4 expression in the colorectal cancer cell lines HCT116, SW620 and DLD-1. Cell lines with reduced S100A4 expression showed reduced cell migration and invasion in vitro. The knock-down of S100A4 expression also led to significantly diminished formation of liver metastases when intrasplenically transplanted in mice (P = 0.004). We then focused on the therapeutic potential of systemically applied shRNA expression plasmids acting on S100A4 via repeated hydrodynamics-based tail vein injection of plasmid DNA. Mice, intrasplenically transplanted with HCT116 cells and treated systemically with S100A4-shRNA plasmids, showed a decrease of S100A4 and MMP9 expression levels, resulting in significantly reduced liver metastases (P = 0.005). In summary, we show for the first time the intratumoral knock-down of S100A4 via systemic application of S100A4-shRNA plasmid DNA, which restricts metastasis formation in a xenografted mouse model of colorectal cancer.

Hornerin, an S100 family protein, is functional in breast cells and aberrantly expressed in breast cancer

Background

Recent evidence suggests an emerging role for S100 protein in breast cancer and tumor progression. These ubiquitous proteins are involved in numerous normal and pathological cell functions including inflammatory and immune responses, Ca²⁺ homeostasis, the dynamics of cytoskeleton constituents, as well as cell proliferation, differentiation, and death. Our previous proteomic analysis demonstrated the presence of hornerin, an S100 family member, in breast tissue and extracellular matrix. Hornerin has been reported in healthy skin as well as psoriatic and regenerating skin after wound healing, suggesting a role in inflammatory/immune response or proliferation. In the present study we investigated hornerin’s potential role in normal breast cells and breast cancer.

Methods

The expression levels and localization of hornerin in human breast tissue, breast tumor biopsies, primary breast cells and breast cancer cell lines, as well as murine mammary tissue were measured via immunohistochemistry, western blot analysis and PCR. Antibodies were developed against the N- and C-terminus of the protein for detection of proteolytic fragments and their specific subcellular localization via fluorescent immunocytochemisty. Lastly, cells were treated with H₂O₂ to detect changes in hornerin expression during induction of apoptosis/necrosis.

Results

Breast epithelial cells and stromal fibroblasts and macrophages express hornerin and show unique regulation of expression during distinct phases of mammary development. Furthermore, hornerin expression is decreased in invasive ductal carcinomas compared to invasive lobular carcinomas and less aggressive breast carcinoma phenotypes, and cellular expression of hornerin is altered during induction of apoptosis. Finally, we demonstrate the presence of post-translational fragments that display differential subcellular localization.

Conclusions

Our data opens new possibilities for hornerin and its proteolytic fragments in the control of mammary cell function and breast cancer.

Downregulation of S100A4 expression by RNA interference suppresses cell growth and invasion in human colorectal cancer cells

S100A4 protein, a member of the S100 superfamily of calcium-binding proteins, is frequently observed in various types of human cancers, including colorectal cancer (CRC). Our previous investigations have demonstrated that the overexpression of S100A4 is associated with lymph node metastasis and poor prognosis in CRC; however, its biological roles in CRC remain unclear. In the present study, we compared the expression of S100A4 at the mRNA and protein levels in six CRC cell lines, and found that the expression levels roughly coincided with their invasiveness. Using RNA interference, we suppressed S100A4 expression in SW620 CRC cells with highly invasive potential and S100A4 high expression. The specific knockdown of S100A4 strongly suppressed cell growth, migration and invasion activities. Furthermore, employing metastasis-related gene mRNA microarrays, we found four genes to be significantly dysregulated (more than 2-fold) after downregulation of S100A4, including three downregulated genes (MMP9, MMP10 and CDH11) and one upregulated gene (TIMP4). Our present results indicate that S100A4 may positively regulate tumor cell proliferation, invasion and metastasis associated with multiple molecules. Thus, the inhibition of S100A4 might be a potentially novel approach to treatment for CRC.

The cardiac fibroblast: functional and electrophysiological considerations in healthy and diseased hearts

Cardiac fibrosis occurs in a number of cardiovascular diseases associated with a high incidence of arrhythmias. A critical event in the development of fibrosis is the transformation of fibroblasts into an active phenotype or myofibroblast. This transformation results in functional changes including increased proliferation and changes in the release of signaling molecules and extracellular matrix deposition. Traditionally, fibroblasts have been considered to affect cardiac electrophysiology indirectly by physically isolating myocytes and creating conduction barriers. There is now increasing evidence that cardiac fibroblasts may play a direct role in modulating the electrophysiological substrate in diseased hearts. The purpose of this review is to summarize the functional changes associated with fibroblast activation, the membrane currents that have been identified in adult cardiac fibroblasts, and describe recent studies of fibroblast-myocyte electrical interactions with emphasis on the changes that occur with cardiac injury. Further analysis of fibroblast membrane electrophysiology and their interactions with myocytes will lead to a more complete understanding of the arrhythmic substrate. These studies have the potential to generate new therapeutic approaches for the prevention of arrhythmias associated with cardiac fibrosis.

S100A4 mediated cell invasion and metastasis of esophageal squamous cell carcinoma via the regulation of MMP-2 and E-cadherin activity

It is well documented that S100A4 is upregulated in a large amount of invasive tumors and plays a pivotal role in tumor invasion and metastasis. However, the precise role and mechanism S100A4 exerts in the invasion and metastasis of esophageal squamous cell carcinoma (ESCC) have not been fully elucidated to date. Our data demonstrated that S100A4 was overexpressed in human ESCC tissues, especially in ESCC with poor differentiation, deep invasion and lymph node metastasis. Subsequently, the knockdown of S100A4 by RNAi in ESCC cell line (EC-1) could reduce cell invasion, metastasis and proliferation ability in vitro. Most importantly, S100A4 regulated MMP-2 positively and E-cadherin negatively in vivo and in vitro to some extent. Our results suggest that S100A4 is an important factor in the invasion, metastasis and proliferation of ESCC and may control invasion and metastasis at least in part through the regulation of MMP-2 and E-cadherin activity. S100A4 may serve as a biomarker for progression of ESCC and a potential molecular target for biotherapy of ESCC.

Expression of protein S100A4 is a predictor of recurrence in colorectal cancer

AIM: To investigate the prognostic significance of S100A4 expression in colorectal cancer and its correlation with expression of E-cadherin and p53.

METHODS: A cohort of archival formalin-fixed paraffin-embedded specimens was selected from 127 patients with colorectal cancer who underwent surgical resection between April 2000 and March 2004 at the Department of Surgery, Korea University Guro Hospital. The expression of protein S100A4 was evaluated according to the proportion of positively stained cancer cells. In each case, three core biopsies with a diameter of 2 mm were punched out and positioned in a recipient paraffin array block. Four-μm sections of these tissue array blocks were used for immunohistochemical analysis of protein S100A4, E-cadherin, and p53. Clinicopathological data were based on the original histopathologic reports and clinical records of patients.

RESULTS: In normal colorectal mucosa, protein S100A4 immunoreactivity was clearly absent in both cytoplasm and nucleus. However, positive immunoreactivity of protein S100A4 was detected in 45 (35.4%) of the tumor cases. There was no significant association between positive immunoreactivity of protein S100A4 and clinicopathological parameters such as tumor differentiation or TNM stage, and also no correlation between the reactivity and E-cadherin or p53 expression. However, positive immunoreactivity of protein S100A4 was found to be associated with tumor recurrence (P = 0.004), and was also associated with significantly worse overall survival in the Kaplan-Meyer survival analysis (P = 0.044). After adjustment for tumor differentiation, tumor depth and nodal status, however, it failed to achieve statistical significance (P = 0.067).

CONCLUSION: The expression of protein S100A4 is associated with tumor recurrence and poor overall survival in patients with colorectal cancer.

Significance of S100A2 and S100A4 Expression in the Progression of Prostate Adenocarcinoma

Purpose

The aim of this study was to investigate the expression pattern of calcium-binding proteins S100A2 and S100A4. We also sought to determine the prognostic value of these markers for patients with prostate adenocarcinoma.

Materials and Methods

Immunohistochemical staining was performed to detect S100A2 and S100A4 expression in 26 tissue samples obtained during transurethral resection from patients with benign prostatic hyperplasia (BPH) and in 67 tissue samples obtained during prostate biopsy and radical prostatectomy from patients with prostate carcinoma. The immunoreactivity of these proteins was stratified on a scale of 0 to 3 and was correlated with the pathologic features of prostate adenocarcinoma.

Results

High expression of S100A2 was observed in the tissue of patients with BPH, whereas low or no expression was observed in prostate cancer (CaP) cells. The protein level of S100A4 was significantly higher in CaP than in BPH cells. The higher level of S100A4 observed in CaP tissue correlated with increasing tumor grade.

Conclusions

Decreased expression of S100A2 and increased expression of S100A4 may be important in the progression of CaP. This finding could aid in identifying aggressive CaP. The simultaneous analysis of S100A2 and S100A4 expression in prostate tissues may be a useful prognostic marker for CaP.

Arterially delivered mesenchymal stem cells prevent obstruction-induced renal fibrosis

BACKGROUND

Mesenchymal stem cells (MSCs) hold promise for the treatment of renal disease. While MSCs have been shown to accelerate recovery and prevent acute renal failure in multiple disease models, the effect of MSC therapy on chronic obstruction-induced renal fibrosis has not previously been evaluated.

MATERIALS AND METHODS

Male Sprague-Dawley rats underwent renal artery injection of vehicle or fluorescent-labeled human bone marrow-derived MSCs immediately prior to sham operation or induction of left ureteral obstruction (UUO). One or 4 wk later, the kidneys were harvested and the renal cortex analyzed for evidence of stem cell infiltration, epithelial-mesenchymal transition (EMT) as evidenced by E-cadherin/α-smooth muscle actin (α-SMA) expression and fibroblast specific protein (FSP+) staining, renal fibrosis (collagen content, Masson's trichrome staining), and cytokine and growth factor activity (ELISA and real time RT-PCR).

RESULTS

Fluorescent-labeled MSCs were detected in the interstitium of the kidney up to 4 wk post-obstruction. Arterially delivered MSCs significantly reduced obstruction-induced α-SMA expression, FSP+ cell accumulation, total collagen content, and tubulointerstitial fibrosis, while simultaneously preserving E-cadherin expression, suggesting that MSCs prevent obstruction-induced EMT and renal fibrosis. Exogenous MSCs reduced obstruction-induced tumor necrosis factor-α (TNF-α) levels, but did not alter transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), interleukin-10 (IL-10), fibroblast growth factor (FGF), or hepatocyte growth factor (HGF) expression.

CONCLUSIONS

Human bone marrow-derived MSCs remain viable several weeks after delivery into the kidney and provide protection against obstruction-induced EMT and chronic renal fibrosis. While the mechanism of MSCs-induced renal protection during obstruction remains unclear, our results demonstrate that alterations in TNF-α production may be involved.

Autophagy is a component of epithelial cell fate in obstructive uropathy

Epithelial cell fate and nephron loss in obstructive uropathy are not fully understood. We produced transgenic mice in which epithelial cells in the nephrons and collecting ducts were labeled with enhanced yellow fluorescent protein, and tracked the fate of these cells following unilateral ureteral obstruction (UUO). UUO led to a decrease in the number of enhanced yellow fluorescent protein-expressing cells and down-regulation of epithelial markers, E-cadherin, and hepatocyte nuclear factor-1beta. Following UUO, enhanced yellow fluorescent protein-positive cells were confined within the tubular basement membrane, were not found in the renal interstitium, and did not express alpha-smooth muscle actin or S100A4, markers of myofibroblasts and fibroblasts. Moreover, when proximal tubules were labeled with dextran before UUO, dextran-retaining cells did not migrate into the interstitium or express alpha-smooth muscle actin. These results indicate that UUO leads to tubular epithelial loss but does not cause epithelial-to-mesenchymal transition that has been shown by others to be responsible for nephron loss and interstitial fibrosis. For the first time, we found evidence of enhanced autophagy in obstructed tubules, including accumulation of autophagosomes, increased expression of Beclin 1, and increased conversion of microtubular-associated protein 1 light chain 3-I to -II. Increased autophagy may represent a mechanism of tubular survival or may contribute to excessive cell death and tubular atrophy after obstructive injury.

Toll-like receptor 4: a novel signaling pathway during renal fibrogenesis

BACKGROUND

The toll-like receptor (TLR) family serves an important regulatory role in the innate immune system, and recent evidence has implicated TLR signaling in the pro-inflammatory response of a variety of endogenous and exogenous stimuli within the kidney. The role of TLR signaling in fibrotic renal injury, however, remains unknown.

MATERIALS AND METHODS

C3H/HeJ TLR4 hyporesponsive mice (TLR4(Lps-d)) or WT controls (C3H/HeOu/J) underwent either sham operation or 1 wk of unilateral ureteral obstruction (UUO). The kidneys were harvested and tissues were analyzed for TLR4 expression (Western blot; RTPCR), E-cadherin and alpha smooth muscle actin (α-SMA) expression (Western blot), fibroblast accumulation (fibroblast specific protein (FSP-1+) staining), renal fibrosis (collagen I RTPCR, total collagen assay, Masson's trichrome staining), cytokine gene expression (tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta1 (TGF-β1) RTPCR), and pSMAD2 and integrin α1 expression (Western blot).

RESULTS

Mice with intact TLR4 signaling demonstrate a significant increase in TLR4 expression, α-SMA expression, fibroblast accumulation, collagen deposition, and interstitial fibrosis, and a significant decrease in E-cadherin expression in response to UUO. TLR4 deficient mice, however, exhibit a significant reduction in obstruction-induced α-SMA expression, fibroblast accumulation, and renal fibrosis, with preservation of E-cadherin expression. TLR4's influence on fibroblast accumulation and renal fibrosis occurred independent of any alterations in TNF-α, TGF-β1, or pSMAD2 expression, but did involve alterations integrin α1 expression.

CONCLUSION

TLR4 appears to be a significant mediator of fibrotic renal injury. While TLR4 signaling is recognized as a critical component of the innate immune response, this is the first study to demonstrate a novel role for TLR4 in renal fibroblast accumulation and tubulointerstitial fibrosis.

Integrin (alpha6beta4) signals through Src to increase expression of S100A4, a metastasis-promoting factor: implications for cancer cell invasion

Integrin alpha6beta4 is linked to cancer cell motility and invasion in aggressive and metastatic cancer cells. In this study, we showed that expression of the beta4 integrin in MDA-MB-435 cancer cells (MDA-MB-435/beta4) leads to a dramatic increase in expression of a metastasis-promoting factor, S100A4, as determined by affymetrix gene chip microarray, quantitative real-time PCR, and Western blot analysis. Alternatively, knocking down beta4 integrin expression in MDA-MB-231 breast carcinoma cells by shRNA reduced the level of S100A4 expression. The mechanism by which alpha6beta4 enhances S100A4 expression involves Src, Akt, and NFAT. We have further shown that Y1494, a tyrosine residue of the ITIM motif in the cytoplasmic domain of the beta4 integrin subunit, is essential for alpha6beta4-dependent S100A4 expression. Reduction of S100A4 expression by shRNA blocked migration, invasion, and anchorage-independent growth of MDA-MB-435/beta4, SUM-159, and MDA-MB-231 cells. These studies define a novel mechanism by which integrin alpha6beta4 promotes cancer cell motility and invasion, and provides insight into how S100A4 expression is regulated in cancer cells.

Epithelial-mesenchymal transition as a potential explanation for podocyte depletion in diabetic nephropathy

BACKGROUND

Depletion of glomerular podocytes is an important feature of progressive diabetic nephropathy. Although the most plausible explanation for this podocyte depletion is detachment from the glomerular basement membrane after cellular apoptosis, the mechanism is unclear. Fibroblast-specific protein 1 (FSP1; encoded by the S100A4 gene) is a member of the S100 family of calcium-binding proteins and is constitutively expressed in the cytoplasm of tissue fibroblasts or epithelial cells converted into fibroblasts by means of epithelial-mesenchymal transition.

STUDY DESIGN

Retrospective cross-sectional analysis.

SETTINGS & PARTICIPANTS

109 patients with type 2 diabetes mellitus, of whom 43 (39%) underwent kidney biopsy.

PREDICTOR

Clinical stage (4 categories) and histological grade (5 categories) of diabetic nephropathy.

OUTCOME

FSP1 expression in podocytes in urine and glomeruli in kidney biopsy specimens.

MEASUREMENTS

Immunohistochemistry, real-time polymerase chain reaction, and in situ hybridization.

RESULTS

38 of 109 patients (35%) were normoalbuminuric, 16 (15%) had microalbuminuria, 8 (7%) had macroalbuminuria, and 47 (43%) had decreased kidney function. Approximately 95% of podocytes in urine sediment were not apoptotic, and 86% expressed FSP1. The number of FSP1-positive podocytes in urine sediment was significantly larger in patients with macroalbuminuria than in those with normoalbuminuria (P = 0.03). Intraglomerular expression of FSP1 occurred almost exclusively in podocytes from patients with diabetes, and the number of FSP1-positive podocytes was larger in glomeruli showing diffuse mesangiopathy than in those showing focal mesangiopathy (P = 0.01). The number also was larger in glomeruli with nodular lesions than in those without nodular lesions (P < 0.001). FSP1-positive podocytes selectively expressed Snail1 and integrin-linked kinase, a known trigger for epithelial-mesenchymal transition.

LIMITATIONS

Nonrepresentative study population.

CONCLUSIONS

These results suggest that the appearance of FSP1 in podocytes of patients with diabetes is associated with more severe clinical and pathological findings of diabetic nephropathy, perhaps because of induction of podocyte detachment through epithelial-mesenchymal transition-like phenomena.

A novel cell-permeable antioxidant peptide decreases renal tubular apoptosis and damage in unilateral ureteral obstruction

Unilateral ureteral obstruction (UUO) is characterized by decreases in renal function, increased interstitial fibrosis, tubular apoptosis, and cellular infiltration. It has been suggested that inhibition of tubular apoptosis may protect against renal damage in obstruction. We have recently developed a series of peptides which are concentrated in the inner mitochondrial membrane and prevent cell death. These peptides are also active in vivo, in myocardial infraction, ischemic brain injury, and amyotrophic lateral sclerosis models. We therefore used SS-31, a prototype of these peptides, and assessed its effects on renal damage and oxidative stress in a 14-day obstruction model. SS-31 (1 or 3 mg/kg) or saline was given 1 day before and throughout the 14 days of obstruction. Kidneys were harvested and assessed for apoptosis (terminal transferase-dUTP-nick-end labeling, caspase 3 expression), fibrosis (trichrome staining), macrophage infiltration, fibroblast expression (immunoperoxidase), and oxidative damage (8-OH deoxyguanosine and heme oxygenase-1 expression), cytokines, and signaling pathways (transforming growth factor-beta, CCR-1, p38-MAPK, NF-kappaB). SS-31 significantly attenuated the effects of obstruction on all aspects of renal damage which were examined, with both the 1 and 3 mg/kg doses showing efficacy. We noted increased oxidative stress in obstruction, which was also attenuated by SS-31 treatment. Signaling via NF-kappaB and p38 MAPK pathways were both affected by SS-31 treatment. This study provides a proof of concept that peptides which protect mitochondria in vitro can provide protection from renal damage in a UUO model. The mechanism by which protection is afforded requires further studies both in vitro and in vivo.

Crystal structure of metastasis-associated protein S100A4 in the active calcium-bound form

S100A4 (metastasin) is a member of the S100 family of calcium-binding proteins that is directly involved in tumorigenesis. Until recently, the only structural information available was the solution NMR structure of the inactive calcium-free form of the protein. Here we report the crystal structure of human S100A4 in the active calcium-bound state at 2.03 A resolution that was solved by molecular replacement in the space group P6(5) with two molecules in the asymmetric unit from perfectly merohedrally twinned crystals. The Ca(2+)-bound S100A4 structure reveals a large conformational change in the three-dimensional structure of the dimeric S100A4 protein upon calcium binding. This calcium-dependent conformational change opens up a hydrophobic binding pocket that is capable of binding to target proteins such as annexin A2, the tumor-suppressor protein p53 and myosin IIA. The structure of the active form of S100A4 provides insight into its interactions with its binding partners and a better understanding of its role in metastasis.

Tissue profiling MALDI mass spectrometry reveals prominent calcium-binding proteins in the proteome of regenerative MRL mouse wounds

MRL/MpJ-Fas(lpr) mice exhibit the ability to regenerate ear tissue excised by dermal punches. This is an exceptional model to identify candidate proteins that may regulate regeneration in typically nonregenerative tissues. Identification of key molecules involved in regeneration can broaden our understanding of the wound-healing process and generate novel therapeutic approaches. Tissue profiling by matrix-assisted laser desorption ionization mass spectrometry is a rapid, powerful proteomic tool that allows hundreds of proteins to be detected from specific regions of intact tissue specimens. To identify these candidate molecules, protein expression in ear punches was examined after 4 and 7 days using tissue profiling of MRL/MpJ-Fas(lpr) mice and the nonregenerative mouse strain C57BL/6J. Spectral analysis revealed distinct proteomic differences between the regenerative and nonregenerative phenotypes, including the calcium-binding proteins calgranulin A and B, calgizzarin, and calmodulin. Spatial distributions for these differentially expressed proteins within the injured regions were confirmed by immunohistochemistry.

S100A4: a common mediator of epithelial-mesenchymal transition, fibrosis and regeneration in diseases?

Multiple reports have focused on S100A4's role in cancer progression, specifically its ability to enhance metastasis. However, recent studies have linked S100A4 to several diseases besides cancer, including kidney fibrosis, cirrhosis, pulmonary disease, cardiac hypertrophy and fibrosis, arthritis and neuronal injuries. Common to all these diseases is the involvement of fibrotic and inflammatory processes, i.e. processes greatly dependent on tissue remodelling, cell motility and epithelial-mesenchymal transition. Therefore, the basic biological mechanisms behind S100A4's effects are emerging. S100A4 belongs to the S100 family of proteins that contain two Ca2+-binding sites including a canonical EF-hand motif. S100A4 is involved in the regulation of a wide range of biological effects including cell motility, survival, differentiation and contractility. S100A4 has both intracellular and extracellular effects. Hence, S100A4 interacts with cytoskeletal proteins and enhances metastasis of several types of cancer cells. In addition, S100A4 is secreted by unknown mechanisms, thus, paracrinely stimulating a variety of cellular responses, including angiogenesis and neuronal growth. Although many cellular effects of S100A4 are well described, the molecular mechanisms whereby S100A4 elicits these responses remain largely unknown. However, it is likely that the intracellular and the extracellular effects involve distinct mechanisms. In this review, we explore the possible roles of S100A4 in non-cancer diseases and employ this knowledge to describe underlying biological mechanisms including a change in cellular phenotype towards less tightly adherent cells and activation of fibrotic processes that may explain this protein's involvement in multiple pathologies.

Multipotent mesenchymal stromal cells obtained from diverse human tissues share functional properties and gene-expression profile with CD146+ perivascular cells and fibroblasts

OBJECTIVE

The relationship of multipotent mesenchymal stromal cells (MSC) with pericytes and fibroblasts has not been established thus far, although they share many markers of primitive marrow stromal cells and the osteogenic, adipogenic, and chondrogenic differentiation potentials.

MATERIALS AND METHODS

We compared MSCs from adult or fetal tissues, MSC differentiated in vitro, fibroblasts and cultures of retinal pericytes obtained either by separation with anti-CD146 or adhesion. The characterizations included morphological, immunophenotypic, gene-expression profile, and differentiation potential.

RESULTS

Osteogenic, adipocytic, and chondrocytic differentiation was demonstrated for MSC, retinal perivascular cells, and fibroblasts. Cell morphology and the phenotypes defined by 22 markers were very similar. Analysis of the global gene expression obtained by serial analysis of gene expression for 17 libraries and by reverse transcription polymerase chain reaction of 39 selected genes from 31 different cell cultures, revealed similarities among MSC, retinal perivascular cells, and hepatic stellate cells. Despite this overall similarity, there was a heterogeneous expression of genes related to angiogenesis, in MSC derived from veins, artery, perivascular cells, and fibroblasts. Evaluation of typical pericyte and MSC transcripts, such as NG2, CD146, CD271, and CD140B on CD146 selected perivascular cells and MSC by real-time polymerase chain reaction confirm the relationship between these two cell types. Furthermore, the inverse correlation between fibroblast-specific protein-1 and CD146 transcripts observed on pericytes, MSC, and fibroblasts highlight their potential use as markers of this differentiation pathway.

CONCLUSION

Our results indicate that human MSC and pericytes are similar cells located in the wall of the vasculature, where they function as cell sources for repair and tissue maintenance, whereas fibroblasts are more differentiated cells with more restricted differentiation potential.

Epithelial-mesenchymal transition contributes to portal tract fibrogenesis during human chronic liver disease

The relationship between bile duct damage and portal fibrosis in chronic liver diseases remains unclear. This study was designed to show whether human intrahepatic biliary epithelial cells can undergo epithelial-mesenchymal cell transition, thereby directly contributing to fibrogenesis. Primary human cholangiocytes were stimulated with transforming growth factor-beta (TGFbeta) or TGFbeta-presenting T cells and examined for evidence of transition to a mesenchymal phenotype. Liver sections were labelled to detect antigens associated with biliary epithelial cells (cytokeratin 7 and 19 and E-cadherin), T cells (CD8), epithelial-mesenchymal transition (S100A4, vimentin and matrix metalloproteinase-2 (MMP-2)), myofibroblasts (alpha-smooth muscle actin) and intracellular signal-transduction mediated by phosphorylated (p)Smad 2/3; in situ hybridisation was performed to detect mRNA encoding TGFbeta and S100A4. Stimulation of cultured cells with TGFbeta induced the expression of pSmad2/3, S100A4 and alpha-smooth muscle actin; these cells became highly motile. Although normal bile ducts expressed ALK5 (TGFbeta RI), low levels of TGFbeta mRNA and nuclear pSmad2/3, they did not express S100A4, vimentin or MMP-2. However, TGFbeta mRNA and nuclear pSmad2/3 were strongly expressed in damaged ducts, which also expressed S100A4, vimentin and MMP-2. Fibroblast-like cells which expressed S100A4 were present around many damaged bile ducts. Cells in the 'ductular reaction' expressed both epithelial and mesenchymal markers together with high levels of TGFbeta mRNA and pSmad2/3. In conclusion, the cells forming small- and medium-sized bile ducts and the ductular reaction undergo EMT during chronic liver diseases, resulting in the formation of invasive fibroblasts; this process may be driven by a response to local TGFbeta, possibly presented by infiltrating T cells.

Dysregulation of matrix metalloproteinases and their tissue inhibitors by S100A4

The S100A4 protein as well as the matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are associated with diseases such as arthritis and cancer. This mini review focuses on in vitro and in vivo studies indicating S100A4 involvement in regulation of MMPs and TIMPs, and the biological and pathobiological consequences of this regulation.

A novel methodology to probe endothelial differential gene expression profile reveals novel genes

Endothelial dysfunction is a major feature of vascular diseases. A practical, minimally invasive method to effectively "probe" gene transcription for an individual patient's endothelium has potential to "customize" assessment for an individual at risk of vascular disease as well as pathophysiologic insight in an in vivo human, clinical context. Published literature lacks a methodology to identify endothelial differential gene expression in individuals with vascular disease. We describe a methodology to do so. The aim of this study was to specifically utilize (a) cutaneous microvascular biopsy, (b) laser capture microdissection, (c) cDNA amplification, (d) suppression subtractive hybridization, (e) high-throughput sequencing techniques, (f) real-time polymerase chain reaction (PCR), and (g) in combination of these methods, to profile differential gene expression in the context of cardiovascular and cerebrovascular disease. Endothelial cells were obtained by laser capture microdissection from a patient and a healthy sibling's microvascular biopsy tissues. Endothelial RNA was extracted, reverse transcribed, and amplified to ds cDNA. Suppression subtractive hybridization was used to establish an endothelial differential gene expression library. Real-time PCR confirmed SERP1, caspase 8, IGFBP7, S100A4, F85, and F147 up-regulation between 1.4- and 3.47-fold. The authors have successfully established a methodology to profile endothelial differential gene expression and identified six differentially expressed genes. This minimally invasive novel method has potential wide application in the customized assessment of many patients suffering vascular diseases.

Expression of S100A2 and S100A4 predicts for disease progression and patient survival in bladder cancer

OBJECTIVES

To determine the expression patterns and prognostic value of S100A2 and S100A4 in surgical specimens from radical cystectomy for transitional cell carcinoma of the urinary bladder.

METHODS

Immunohistochemical staining for S100A2 and S100A4 was performed in 92 archived radical cystectomy and 38 normal specimens. The immunoreactivity of these proteins was stratified on a 0 to 6 scale and then correlated with the pathologic features and clinical outcome.

RESULTS

S100A2 expression was significantly decreased in the bladder cancer specimens compared with the controls (P <0.0001), and S100A4 expression was significantly greater in the bladder cancer specimens (P = 0.03). The loss of expression of S100A2 and increased expression of S100A4 were associated with muscle invasion (P <0.05). These alterations in expression were also associated with a greater risk of disease progression and a decreased chance of cancer-specific survival at a median follow-up of 25.3 months (P <0.0001 for both). After adjusting for the effects of the pathologic findings, S100A4 expression remained a significant predictor of disease progression (P <0.0001) and cancer-specific survival (P <0.0001).

CONCLUSIONS

S100A4 appeared to be an independent predictor for the treatment outcome in bladder cancer. The expression patterns of S100A2 and S100A4 correlated well with the pathologic stage, disease progression, and cancer-specific mortality. This finding could aid in identifying more biologically aggressive cancers and thus patients who might benefit from more intensive adjuvant therapy.

A review of the S100 proteins in cancer

AIM

In the quest to reduce mortality and morbidity from cancer, there is continued effort to identify novel biomarkers to aid in the early detection and the accurate prediction of tumour behaviour. One group of proteins that is emerging as a potentially important group of markers in multiple tumour types is the S100 family. This review summarises the biological and clinical relevance of these proteins in relation to different tumour types.

METHODS

A literature search was performed using the PubMed database and the reference lists of relevant articles. Single case studies were excluded and only reports with a clinical relevance from 1961 to 2007 were included.

RESULTS

The search yielded over 1000 published articles and reports. Important reports and studies were reviewed, screened and tracked for further relevant publications. Only the most relevant publications are discussed with relation to individual members of the S100 family.

CONCLUSION

There is increasing evidence that altered expression of S100 family members is seen in many cancers including breast, lung, bladder, kidney, thyroid, gastric, prostate and oral cancers. S100 proteins are commonly up-regulated in tumours and this is often associated with tumour progression. In contrast S100A2, S100A11 and S100A9 have been documented as tumour suppressors in some cancers but as tumour promoters in others. This demonstrates the complexity of the family and variability of their functions. Although the precise roles of these proteins in cancer is still to be discovered many of the family are associated with promoting metastases through interactions with matrix metalloproteinases or by acting as chemoattractants. There is also evidence that some members can regulate transcription factors such as p53. S100B already has a role in a clinical setting in the diagnosis and therapeutic monitoring of malignant melanoma. As our understanding of this family develops it is likely that many more members will aid the diagnosis, monitoring and potential treatment of cancers in the future.

Effect of combination therapy with enalapril and the TGF-β antagonist 1D11 in unilateral ureteral obstruction

In unilateral ureteral obstruction (UUO), the kidney is characterized by increased fibrosis and apoptosis. Both transforming growth factor-β (TGF-β) and ANG II have been implicated, and ANG II may mediate its effects through TGF-β. Previous studies demonstrated amelioration of renal damage when either TGF-β or ANG II has been individually targeted. In this study, we sought to determine whether combining 1D11 (monoclonal antibody to TGF-β) and an ACE inhibitor, enalapril, would be more effective in UUO than either individual treatment, as has been shown in diabetic and glomerulonephritic models. Rats underwent UUO and were given either control monoclonal antibody, 1D11 or enalapril, or 1D11/enalapril combination, for 14 days. Kidneys were harvested and examined for fibrosis [trichrome; collagen (real-time PCR, Sircol assay) and fibroblast-specific protein expression (immunohistochemistry), apoptosis (TUNEL), macrophage infiltration (immunohistochemistry), and TGF-β expression (real-time PCR and tubular localization with immunohistochemistry)]. UUO was found to induce fibrosis, apoptosis, macrophage infiltration, and TGF-β expression in the obstructed kidney. Administration of either 1D11 or enalapril individually significantly decreased all these changes; when 1D11 and enalapril were combined, there was little additive effect, and the combination did not provide full protection against damage. The results demonstrate that, for the most part, combination therapy is not additive in UUO. This could be due to the continued presence of a physical obstruction or to biochemical differences between UUO and other renal disease models. Furthermore, it suggests that other targets may be amenable to pharmacological manipulation in UUO.

Identification of metastasis candidate proteins among HCC cell lines by comparative proteome and biological function analysis of S100A4 in metastasis in vitro

Widespread metastasis of hepatocellular carcinoma (HCC) was a complex cascade of events, which is still beyond full appreciation. Screening key proteins, which play a critical role in metastasis, using high-throughput proteomics approach help discover valuable biomarkers and elucidate the mechanism of metastasis. This study was to find out some metastasis candidate proteins among HCC cell lines with various metastatic potential by comparative proteomics, and then further validate the biological function of these proteins in metastasis in vitro. The protein profiles of metastatic HCC cell lines (MHCC97H and MHCC97L) displayed obvious differences compared with nonmetastatic ones (Hep3B). Twenty-six metastasis candidate proteins, which were identified by on-line LC-ESI-MS/MS, such as S100 calcium-binding protein A4 (S100A4), annexin 1, etc., might have much application in diagnostic procedures and prognosis evaluation. S100A4, as a leading different metastasis candidate protein, which overexpressed only in the metastatic cells, was selected for further investigation. A series of assays related to invasion and metastasis in vitro, including cell motility, invasion, and matrix metalloproteinases (MMPs) secretion, were performed in MHCC97H/antisense recombinant plasmid to S100A4 (pcDNA3.1(+) AS S100A4) and the mock controls. All the data in the present study suggested that S100A4 might contribute to HCC invasion and metastasis through two paths of matrix metalloproteinase (MMP9) secretion regulation and strengthened motility and invasion properties.

Testosterone treatment promotes tubular damage in experimental diabetes in prepubertal rats

Puberty unmasks or accelerates progressive kidney diseases, including diabetes mellitus (DM), perhaps through effects of sex steroids. To test the hypothesis that rising androgen levels at puberty permit diabetic kidney damage, we studied four groups of male rats with and without streptozocin-induced DM: adult onset (A), adult onset after castration (AC), juvenile onset (J), and juvenile onset with testosterone treatment (JT). Profibrotic markers were measured after 6 wk with blood glucose levels 300-450 mg/dl. JT permitted increased expression of mRNA for two isoforms of transforming growth factor-beta and connective tissue growth factor compared with J animals with DM; prior castration did not provide protection in adult-onset DM. JT also permitted greater tubular staining for alpha-smooth muscle actin and fibroblast-specific protein, two markers of cell damage and potential epithelial mesenchymal transition. Once again, castration was not protective for these effects of DM in the AC group. These data indicate that puberty permits detrimental effects in the tubulointerstitium in the diabetic kidney, an effect mimicked by testosterone treatment of juvenile animals and partially blunted by castration of adults, but damage does not correlate with testosterone levels, suggesting a less direct mechanism.

Expression of the calcium-binding protein S100A4 is markedly up-regulated by osmotic stress and is involved in the renal osmoadaptive response

Proteomic analysis of Inner Medullary Collecting Duct (IMCD3) cells adapted to increasing levels of tonicity (300, 600, and 900 mosmol/kg H(2)O) by two-dimensional difference gel electrophoresis and mass spectrometry revealed several proteins as yet unknown to be up-regulated in response to hypertonic stress. Of these proteins, one of the most robustly up-regulated (22-fold) was S100A4. The identity of the protein was verified by high pressure liquid chromatography-mass spectrometry. Western blot analysis confirmed increased expression with increased tonicity, both acute and chronic. S100A4 protein expression was further confirmed by immunocytochemical analysis. Cells grown in isotonic conditions showed complete absence of immunostaining, whereas chronically adapted IMCD3 cells had uniform cytoplasmic localization. The protein is also regulated in vivo as in mouse kidney tissues S100A4 expression was many -fold greater in the papilla as compared with the cortex and increased further in the papilla upon 36 h of thirsting. Increased expression of S100A4 was also observed in the medulla and papilla, but not the cortex of a human kidney. Data from Affymetrix gene chip analysis and quantitative PCR also revealed increased S100A4 message in IMCD3 cells adapted to hypertonicity. The initial expression of message increased at 8-10 h following exposure to acute sublethal hypertonic stress (550 mosmol/kg H(2)O). Protein and message half-life in IMCD3 cells were 85.5 and 6.8 h, respectively. Increasing medium tonicity with NaCl, sucrose, mannitol, and choline chloride stimulated S100A4 expression, whereas urea did not. Silencing of S100A4 expression using a stable siRNA vector (pSM2; Open Biosystems) resulted in a 48-h delay in adaptation of IMCD3 cells under sublethal osmotic stress, suggesting S100A4 is involved in the osmoadaptive response. In summary, we describe the heretofore unrecognized up-regulation of a small calcium-binding protein, both in vitro and in vivo, whose absence profoundly delays osmoadaptation and slows cellular growth under hypertonic conditions.

Risk factors for early epithelial to mesenchymal transition in renal grafts

Epithelial-to-mesenchymal transition (EMT) of tubular epithelial cells (TECs) may participate in the pathogenesis of renal fibrosis. We performed a prospective study of EMT markers in protocol biopsies obtained 3 months after engraftment from 56 patients who received deceased donor kidneys and who had stable renal function. The presence of EMT was examined, and quantified by immunohistochemical staining for vimentin and translocation of beta-catenin to the cytoplasm. EMT status was defined as the presence of EMT markers in > or = 10% of TECs. EMT features were virtually absent in implantation biopsies, whereas 41% of the grafts were EMT-positive in the absence of advanced chronic allograft nephropathy. Thirteen patients (23%) had borderline changes or acute rejection. EMT features were more frequent in these patients than in those with normal kidney grafts (vimentin expression, p = 0.003; beta-catenin translocation, p = 0.002). EMT in grafts corresponded with elevated serum creatinine of the donor before the recovery of kidney (p = 0.02) and longer cold ischemia time (p = 0.02). In contrast, the donor age had no influence on the expression of EMT markers. These results suggest that EMT is an early and frequent phenomenon in kidney transplants that could be triggered by immunological and/or ischemic tubular injury.

The metastasis-associated gene S100A4 is a novel target of beta-catenin/T-cell factor signaling in colon cancer

BACKGROUND & AIMS

Activation of the Wnt/beta-catenin pathway is frequently observed in colorectal cancers. Our aim was to elucidate the impact of gain-of-function beta-catenin on the metastasis-associated gene S100A4 in human colon cancer cell lines and tumors.

METHODS

We analyzed cell lines heterozygous for gain-of-function and wild-type beta-catenin, and variants homozygous for gain- or loss-of-function mutation in beta-catenin, for S100A4 expression, cell motility, and in vivo metastasis. beta-catenin-mediated S100A4 promoter activation was tested by reporter assays. For human colon carcinomas, S100A4 expression, beta-catenin genotype, and metachronous metastasis were correlated.

RESULTS

We identified S100A4 as the most regulated gene by gain-of-function beta-catenin using a 10K microarray. Cell lines with gain-of-function beta-catenin expressed up to 60-fold elevated S100A4 levels, displayed strongly increased migration and invasion in vitro, and induced metastasis in mice. S100A4 small interfering RNA, beta-catenin small interfering RNA, or dominant negative T-cell factor (TCF) knocked down S100A4 and blocked biological effects. S100A4 complementary DNA transfection increased migration and invasion. We identified a TCF binding site within the S100A4 promoter and demonstrated the direct binding of heterodimeric beta-catenin/TCF complexes. Reporter assays confirmed the beta-catenin-induced S100A4 promoter activity. Furthermore, S100A4 mRNA expression was increased in primary colon cancers, which later developed distant metastases, compared to non-metastasizing tumors. Colon tumors heterozygous for gain-of-function beta-catenin showed concomitant nuclear beta-catenin localization, high S100A4 expression, and metastases.

CONCLUSIONS

S100A4 is a direct beta-catenin/TCF target, induces migration and invasion in vitro and metastasis in vivo, and has value for prognosis of metastasis formation in colon cancer patients.

Regulation of calcium homeostasis by S100RVP, an androgen-regulated S100 protein in the rat ventral prostate

BACKGROUND

S100RVP was previously identified as an androgen-response gene in the rat ventral prostate (RVP). Characterization of S100RVP is important for elucidating the function of S100 proteins in androgen action.

METHODS

The expression and subcellular localization of S100RVP were determined by Northern blot, in situ hybridization, and fluorescent microscopy. Calcium overlay and calcium ionophore sensitivity assays were performed to investigate the calcium binding and function of S100RVP.

RESULTS

S100RVP is abundantly expressed in the RVP epithelial cells. A green fluorescent protein(GFP)-S100RVP fusion protein is present in both the cytoplasm and nucleus of transfected cells. A GST-S100RVP fusion protein bound calcium in vitro at levels similar to known S100 proteins. Furthermore, GFP-S100RVP transfected LNCaP and PC3 cells exhibited reduced sensitivity to calcium ionophore-induced cell death, but not to UV-induced cell death.

CONCLUSION

The results of this study argue for a role of S100RVP in calcium homeostasis in the prostate.

CCNs, fibulin-1C and S100A4 expression in leiomyoma and myometrium: inverse association with TGF-beta and regulation by TGF-beta in leiomyoma and myometrial smooth muscle cells

Connective tissue growth factor (CTGF; CCN2) is considered to serve as downstream midiator of TGF-beta action in tissue fibrosis. We tested this hypothesis in paired leiomyoma and myometrium by evaluating the expression of TGF-beta1/TGF-beta3 and CCN2, the other members of the CCN family, CCN3 and CCN4, as well as fibulin-1C and S100A4, calcium-binding proteins that interact with CCNs. The regulatory function of TGF-beta1 on the expression of these genes was further evaluated using leiomyoma (L) and myometrial (M) smooth muscle cells (SMC). Real-time PCR, Western blotting and immunohistochemistry revealed that leiomyomas and myometrium express CCNs, fibulin-1C and S100A4, whose levels of expression with the exception of fibulin-1C were lower in leiomyomas and inversely correlated with the expression of TGF-beta1 and TGF-beta3 (P<0.05). The expression of these genes was menstrual cycle-independent and GnRHa therapy increased the expression of CCN2 in leiomyomas, while inhibiting CCN3, CCN4 and S100A4 in myometrium (P<0.05). TGF-beta (2.5 ng/ml) in a time- and cell-dependent manner, and through MAPK and Smad pathways, differentially regulated the expression of these genes in LSMC and MSMC. We concluded that CCNs, fibulin-1C and S100A4 are expressed in leiomyomas/myometrium with relative expression levels inversely correlating with TGF-betas and influenced by GnRHa and TGF-beta regulatory actions. The results suggest that unlike other fibrotic disorders, CCN2 (CTGF), at least at tissue level, may not serve as a downstream mediator of TGF-beta action in leiomyomas.

Gene expression in poorly differentiated papillary thyroid carcinomas

We used cDNA microarrays to study gene expression in fresh frozen papillary thyroid carcinoma (PTC) specimens. Seven clinically aggressive carcinomas were included, comprising poorly differentiated PTC and tumors with extensive local invasion or synchronous distant metastases. Ten differentiated (classic) papillary thyroid carcinomas (PTC) and non-neoplastic thyroid tissues were also investigated. TaqMan quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization, and immunohistochemistry verified the differential gene expression. The B-Raf gene was mutated with a T-->A transversion at nucleotide 1799 (V600E) in 8 of 10 differentiated PTC, and in 4 of 7 aggressive carcinomas. Among genes markedly and equally over-expressed in carcinomas of both the aggressive and classic PtC groups, compared to normal thyroid tissue, were CBP/p300 transactivator (CItED1), fibronectin, growth/differentiation factor 15, potassium inwardly rectifying channel KCNJ2, glutaminyl peptide cyclotransferase, WNT7A, and dipeptidyl peptidase IV. A marked upregulation in carcinomas of P-cadherin mRNA and protein concomitant with E-cadherin downregulation, indicates a possible P-E cadherin "switch" in PTC. The growth factor homologue Nel-like 2, dual specificity phosphatase 5, the serine protease kallikrein 10, and also the tight junction genes claudin 1 and claudin 16, were upregulated in classic PTC but not in aggressive tumors, which may be consistent with altered cell polarity in the dedifferentiated PtC. The aggressive, poorly differentiated PtC group was specifically characterized by marked upregulation of several genes related to cell proliferation such as cell division cycle 2 (CDC2), CDC7, kinesin-like 5, ubiquitin conjugating enzyme E2C, and topoisomerase IIalpha, and by upregulation of genes encoding extracellular matrix proteins such as seprase, extracellular matrix protein 1, and several collagens. These aggressive tumors were also characterized by overexpression of the integrin ligand periostin, and in some biopsies also of osteopontin and of the upstream Rac-regulator dedicator of cytokinesis 10 (DOCK10). These data are interpreted to be consistent with altered cell motility, extracellular matrix remodeling and increased cell proliferation, as important processes in PTC tumor progression.