S100A16 promotes acute kidney injury by activating HRD1-induced ubiquitination and degradation of GSK3ß and CK1α.

The pathogenesis of acute kidney injury (AKI) is associated with the activation of multiple signaling pathways, including Wnt/ß-catenin signaling. However, the mechanism of Wnt/ß-catenin pathway activation in renal interstitial fibroblasts during AKI is unclear. S100 calcium-binding protein A16 (S100A16), a new member of calcium-binding protein S100 family, is a multi-functional signaling factor involved in various pathogenies, including tumors, glycolipid metabolism disorder, and chronic kidney disease (CKD). We investigated the potential participation of S100A16 in Wnt/ß-catenin pathway activation during AKI by subjecting wild-type (WT) and S100A16 knockout (S100A16+/-) mice to the ischemia-reperfusion injury (IRI), and revealed S100A16 upregulation in this model, in which knockout of S100A16 impeded the Wnt/ß-catenin signaling pathway activation and recovered the expression of downstream hepatocyte growth factor (HGF). We also found that S100A16 was highly expressed in Platelet-derived growth factor receptor beta (PDGFRß) positive renal fibroblasts in vivo. Consistently, in rat renal interstitial fibroblasts (NRK-49F cells), both hypoxia/reoxygenation and S100A16 overexpression exacerbated fibroblasts apoptosis and inhibited HGF secretion; whereas S100A16 knockdown or Wnt/ß-catenin pathway inhibitor ICG-001 reversed these changes. Mechanistically, we showed that S100A16 promoted Wnt/ß-catenin signaling activation via the ubiquitylation and degradation of ß-catenin complex members, glycogen synthase kinase 3ß (GSK3ß) and casein kinase 1α (CK1α), mediated by E3 ubiquitin ligase, the HMG-CoA reductase degradation protein 1 (HRD1). Our study identified the S100A16 as a key regulator in the activation of Wnt/ß-catenin signaling pathway in AKI.

Allopregnanolone suppresses glioblastoma survival through decreasing DPYSL3 and S100A11 expression.

Allopregnanolone (allo) is a physiological regulator of neuronal activity that treats multiple neurological disorders. Allo penetrates the blood-brain barrier with very high efficiency, implying that allo can treat CNS-related diseases, including glioblastoma (GBM), which always recurs after standard therapy. Hence, this study aimed to determine whether allo has a therapeutic effect on GBM. We found that allo enhanced temozolomide (TMZ)-suppressed cell survival and proliferation of TMZ-resistant cells. In particular, allo enhanced TMZ-inhibited cell migration and TMZ-induced apoptosis. Additionally, allo strongly induced DNA damage characterized by γH2Ax. Furthermore, quantitative proteomic analysis, iTRAQ, showed that allo significantly decreased the levels of DPYSL3, S100A11, and S100A4, reflecting the poor prognosis of patients with GBM confirmed by differential gene expression and survival analysis. Moreover, single-cell RNA-Seq revealed that S100A11, expressed in malignant cells, oligodendrocytes, and macrophages, was significantly associated with immune cell infiltration. Furthermore, overexpression of DPYSL3 or S100A11 prevented allo-induced cell death. In conclusion, allo suppresses GBM cell survival by decreasing DPYSL3/S100A11 expression and inducing DNA damage.

Targeting the S100A2-p53 Interaction with a Series of 3,5-Bis(trifluoromethyl)benzene Sulfonamides: Synthesis and Cytotoxicity.

In silico approaches identified 1, N-(6-((4-bromo- benzyl)amino)hexyl)-3,5-bis(trifluoromethyl)benzene sulfonamide, as a potential inhibitor of the S100A2-p53 protein-protein interaction, a validated pancreatic cancer drug target. Subsequent cytotoxicity screening revealed it to be a 2.97 µM cell growth inhibitor of the MiaPaCa-2 pancreatic cell line. This is in keeping with our hypothesis that inhibiting this interaction would have an anti-pancreatic cancer effect with S100A2, the validated PC drug target. A combination of focused library synthesis (three libraries, 24 compounds total) and cytotoxicity screening identified a propyl alkyl diamine spacer as optimal; the nature of the terminal phenyl substituent had limited impact on observed cytotoxicity, whereas N-methylation was detrimental to activity. In total 15 human cancer cell lines were examined, with most analogues showing broad-spectrum activity. Near uniform activity was observed against a panel of six pancreatic cancer cell lines: MiaPaCa-2, BxPC-3, AsPC-1, Capan-2, HPAC and PANC-1. In all cases there was good to excellent correlation between the predicted docking pose in the S100A2-p53 binding groove and the observed cytotoxicity, especially in the pancreatic cancer cell line with high endogenous S100A2 expression. This supports S100A2 as a pancreatic cancer drug target.

Cytotoxic 1,2,3-Triazoles as Potential Leads Targeting the S100A2-p53 Complex: Synthesis and Cytotoxicity.

In silico screening predicted 1 (N-(4-((4-(3-(4-(3-methoxyphenyl)-1H-1,2,3-triazol-1-yl)propyl)piperazin-1-yl) sulfonyl)-phenyl)acetamide) as an inhibitor of the S100A2-p53 protein-protein interaction. S100A2 is a validated pancreatic cancer drug target. In the MiaPaCa-2 pancreatic cell line, 1 was a ∼50 µM growth inhibitor. Synthesis of five focused compound libraries and cytotoxicity screening revealed increased activity from the presence of electron withdrawing moieties on the sulfonamide aromatic ring, with the 3,5-bis-CF3 Library 3 analogues the most active, with GI50 values of 0.91 (3-ClPh; 13 i; BxPC-3, Pancreas) to 9.0 µM (4-CH3 ; 13 d; PANC-1, Pancreas). Activity was retained against an expanded pancreatic cancer cell line panel (MiaPaCa-2, BxPC-3, AsPC-1, Capan-2, PANC-1 and HPAC) and the normal cell line MCF10A (breast). Bulky 4-disposed substituents on the terminal phenyl ring enhanced broad spectrum activity with growth inhibition values spanning 1.1 to 3.1 µM (4-C(CH3 )3 ; 13 e; BxPC-3 and AsPC-1 (pancreas), respectively). Central alkyl spacer contraction from propyl to ethyl proved detrimental to activity with Library 4 and 5.5- to 10-fold less cytotoxic than the propyl linked Library 2 and Library 3. The data herein was consistent with the predicted binding poses of the compounds evaluated. The highest levels of cytotoxicity were observed with those analogues best capable of adopting a near identical pose to the p53-peptide in the S100A2-p53 binding groove.

Specificity of Molecular Fragments Binding to S100B versus S100A1 as Identified by NMR and Site Identification by Ligand Competitive Saturation (SILCS).

S100B, a biomarker of malignant melanoma, interacts with the p53 protein and diminishes its tumor suppressor function, which makes this S100 family member a promising therapeutic target for treating malignant melanoma. However, it is a challenge to design inhibitors that are specific for S100B in melanoma versus other S100-family members that are important for normal cellular activities. For example, S100A1 is most similar in sequence and structure to S100B, and this S100 protein is important for normal skeletal and cardiac muscle function. Therefore, a combination of NMR and computer aided drug design (CADD) was used to initiate the design of specific S100B inhibitors. Fragment-based screening by NMR, also termed "SAR by NMR," is a well-established method, and was used to examine spectral perturbations in 2D [1H, 15N]-HSQC spectra of Ca2+-bound S100B and Ca2+-bound S100A1, side-by-side, and under identical conditions for comparison. Of the 1000 compounds screened, two were found to be specific for binding Ca2+-bound S100A1 and four were found to be specific for Ca2+-bound S100B, respectively. The NMR spectral perturbations observed in these six data sets were then used to model how each of these small molecule fragments showed specificity for one S100 versus the other using a CADD approach termed Site Identification by Ligand Competitive Saturation (SILCS). In summary, the combination of NMR and computational approaches provided insight into how S100A1 versus S100B bind small molecules specifically, which will enable improved drug design efforts to inhibit elevated S100B in melanoma. Such a fragment-based approach can be used generally to initiate the design of specific inhibitors for other highly homologous drug targets.

Discovery of novel small molecule inhibitors of S100P with in vitro anti-metastatic effects on pancreatic cancer cells.

S100P, a calcium-binding protein, is known to advance tumor progression and metastasis in pancreatic and several other cancers. Herein is described the in silico identification of a putative binding pocket of S100P to identify, synthesize and evaluate novel small molecules with the potential to selectively bind S100P and inhibit its activation of cell survival and metastatic pathways. The virtual screening of a drug-like database against the S100P model led to the identification of over 100 clusters of diverse scaffolds. A representative test set identified a number of structurally unrelated hits that inhibit S100P-RAGE interaction, measured by ELISA, and reduce in vitro cell invasion selectively in S100P-expressing pancreatic cancer cells at 10 µM. This study establishes a proof of concept in the potential for rational design of small molecule S100P inhibitors for drug candidate development.

Role and Mechanisms of RAGE-Ligand Complexes and RAGE-Inhibitors in Cancer Progression.

Interactions of the receptor for advanced glycation end product (RAGE) and its ligands in the context of their role in diabetes mellitus, inflammation, and carcinogenesis have been extensively investigated. This review focuses on the role of RAGE-ligands and anti-RAGE drugs capable of controlling cancer progression. Different studies have demonstrated interaction of RAGE with a diverse range of acidic (negatively charged) ligands such as advanced glycation end products (AGEs), high-mobility group box1 (HMGB1), and S100s, and their importance to cancer progression. Some RAGE-ligands displayed effects on anti- and pro-apoptotic proteins through upregulation of the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), mitogen-activated protein kinases (MAPKs), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and nuclear factor kappa B (NF-κB) pathways, while downregulating p53 in cancer progression. In addition, RAGE may undergo ligand-driven multimodal dimerization or oligomerization mediated through self-association of some of its subunits. We conclude our review by proposing possible future lines of study that could result in control of cancer progression through RAGE inhibition.

Novel protein-inhibitor interactions in site 3 of Ca(2+)-bound S100B as discovered by X-ray crystallography.

Structure-based drug discovery is under way to identify and develop small-molecule S100B inhibitors (SBiXs). Such inhibitors have therapeutic potential for treating malignant melanoma, since high levels of S100B downregulate wild-type p53 tumor suppressor function in this cancer. Computational and X-ray crystallographic studies of two S100B-SBiX complexes are described, and both compounds (apomorphine hydrochloride and ethidium bromide) occupy an area of the S100B hydrophobic cleft which is termed site 3. These data also reveal novel protein-inhibitor interactions which can be used in future drug-design studies to improve SBiX affinity and specificity. Of particular interest, apomorphine hydrochloride showed S100B-dependent killing in melanoma cell assays, although the efficacy exceeds its affinity for S100B and implicates possible off-target contributions. Because there are no structural data available for compounds occupying site 3 alone, these studies contribute towards the structure-based approach to targeting S100B by including interactions with residues in site 3 of S100B.

[Role of S100A4 in the epithelial-mesenchymal transition of esophageal squamous cell carcinoma and its molecular mechanism].

OBJECTIVE: To explore the role of S100A4 in the epithelial-mesenchymal transition (EMT) in esophageal squamous cell carcinoma and its possible molecular mechanism. METHODS: Three chemically synthesized S100A4 siRNA sequences were transiently transfected into esophageal carcinoma EC9706 cells. EC9706 cells transfected with negative siRNA, lipofectamine 2000, and vacant EC9706 cells were used as control. Fluorescence quantitative RT-PCR and Western blot were used to detect the inhibition rate of S100A4 siRNA. S100A4 siRNA2 with the best inhibition rate was chosen to transiently transfect into EC9706 cells under the same conditions. The EC9706 cells transfected with negative siRNA, lipofectamine 2000 and vacant EC9706 cells were also used as control. Fluorescence quantitative RT-PCR and Western blot were used to detect the mRNA and protein expressions of E-cadherin, vimentin and snail. The morphology of EC9706 cells was observed under an inverted microscope. Boyden chamber and scratch test were used to detect the invasion and migration ability of EC9706 cells, and CCK8 assay was used to detect the proliferation ability of EC9706 cells. EC9706 cells transfected with S100A4 siRNA2 were further transfected with snail eukaryotic expression vector. The EC9706 cells transfected with S100A4 siRNA, EC9706 cells transfected with snail eukaryotic expression vector and vacant EC9706 cells were used as control. The above indexes of all the groups were observed, too. RESULTS: The S100A4 mRNA and protein expression levels of the S100A4 siRNA2 group were 0.417 ± 0.041 and 0.337 ± 0.039, the transmembrane cell number was 61.608 ± 8.937, the scratch healing distance was (0.216 ± 0.064) mm, the A value was 0.623 ± 0.084, the E-cadherin mRNA and protein levels were 0.619 ± 0.032 and 0.495 ± 0.034, the vimentin mRNA and protein levels were 0.514 ± 0.032 and 0.427 ± 0.028, the snail mRNA and protein levels were 0.573 ± 0.029 and 0.429 ± 0.041. These data were significantly different with the liposome group, the negative control group and the blank group (P < 0.05 for all). After the S100A4 siRNA2 treatment for 24 h, the appearance of EC9706 cells changed to epithelial cell morphology. The transmembrane cell number and the scratch healing distance of the S100A4 siRNA2+snail eukaryotic expression vector group were (69.382 ± 9.666) cells and (0.274 ± 0.029) mm, the A value was 0.823 ± 0.101, the snail mRNA and protein levels were 0.704 ± 0.037 and 0.625 ± 0.031, the vimentin mRNA and protein levels were 0.712 ± 0.046 and 0.609 ± 0.038, and these data were significantly higher than those of the Sl00A4 siRNA2 group (P < 0.05 for all). The E-cadherin mRNA and protein levels of the S100A4 siRNA2+eukaryotic expression vector group were 0.437 ± 0.038 and 0.381 ± 0.031, significantly lower than those of the S100A4 siRNA2 group (P < 0.05 for all). However, snail had no effect on the morphology of EC9706 cells. CONCLUSIONS: S100A4 may be involved in the EMT process of esophageal squamous-cell carcinoma by regulating the expression of snail and then plays a role in the invasion and metastasis of esophageal carcinoma.

S100A4-neutralizing antibody suppresses spontaneous tumor progression, pre-metastatic niche formation and alters T-cell polarization balance.

BACKGROUND: The tumor microenvironment plays a determinative role in stimulating tumor progression and metastasis. Notably, tumor-stroma signals affect the pattern of infiltrated immune cells and the profile of tumor-released cytokines. Among the known molecules that are engaged in stimulating the metastatic spread of tumor cells is the S100A4 protein. S100A4 is known as an inducer of inflammatory processes and has been shown to attract T-cells to the primary tumor and to the pre-metastatic niche. The present study aims to examine the immunomodulatory role of S100A4 in vivo and in vitro and assess the mode of action of 6B12, a S100A4 neutralizing antibody. METHODS: The therapeutic effect of the 6B12 antibody was evaluated in two different mouse models. First, in a model of spontaneous breast cancer we assessed the dynamics of tumor growth and metastasis. Second, in a model of metastatic niche formation we determined the expression of metastatic niche markers. The levels of cytokine expression were assessed using antibody as well as PCR arrays and the results confirmed by qRT-PCR and ELISA. T-cell phenotyping and in vitro differentiation analyses were performed by flow cytometry. RESULTS: We show that the S100A4 protein alters the expression of transcription factor and signal transduction pathway genes involved in the T-cell lineage differentiation. T-cells challenged with S100A4 demonstrated reduced proportion of Th1-polarized cells shifting the Th1/Th2 balance towards the Th2 pro-tumorigenic phenotype. The 6B12 antibody restored the Th1/Th2 balance. Furthermore, we provide evidence that the 6B12 antibody deploys its anti-metastatic effect, by suppressing the attraction of T-cells to the site of primary tumor and pre-metastatic niche. This was associated with delayed primary tumor growth, decreased vessel density and inhibition of metastases. CONCLUSION: The S100A4 blocking antibody (6B12) reduces tumor growth and metastasis in a model of spontaneous breast cancer. The 6B12 antibody treatment inhibits T cell accumulation at the primary and pre-metastatic tumor sites. The 6B12 antibody acts as an immunomodulatory agent and thus supports the view that the 6B12 antibody is a promising therapeutic candidate to fight cancer.

A Constrained Helical Peptide Against S100A4 Inhibits Cell Motility in Tumor Cells.

S100A4, a member of a calcium-regulated protein family, is involved in various cellular signaling pathways. From many studies over the last decade or so, it has become clear that it is involved in tumor metastasis, probably playing a determinative role. However, except the phenothiazine group of drugs, no significant inhibitor of S100A4 has been reported. Even the phenothiazines are very weak inhibitors of S100A4 action. In this study, we report design and development of a conformationally constrained helical peptide modeled on the non-muscle myosin peptide that binds to S100A4. This conformationally constrained peptide binds to S100A4 with a dissociation constant in the nanomolar range. We also synthesized a peptide for experimental control that bears several alanine mutations in the peptide-protein interface. We demonstrate that the former peptide specifically inhibits motility of H1299 and MCF-7 cells in a wound-healing assay. Structures of several S100A4-ligand complexes suggest that it may be possible to develop a smaller peptide-small molecule conjugate having high affinity for S100A4. Peptide-drug conjugates of this kind may play an important role in developing drug leads against this antimetastasis target.

S100A4 promotes pancreatic cancer progression through a dual signaling pathway mediated by Src and focal adhesion kinase.

S100A4 expression is associated with poor clinical outcomes of patients with pancreatic cancer. The effects of loss or gain of S100A4 were examined in pancreatic cancer cell lines. S100A4 downregulation remarkably reduces cell migration and invasion, inhibits proliferation, and induces apoptosis in pancreatic tumor cells. S100A4 downregulation results in significant cell growth inhibition and apoptosis in response to TGF-ß1, supporting a non-canonical role of S100A4 in pancreatic cancer. The role of S100A4 in tumor progression was studied by using an orthotopic human pancreatic cancer xenograft mouse model. Tumor mass is remarkably decreased in animals injected with S100A4-deficient pancreatic tumor cells. P27(Kip1) expression and cleaved caspase-3 are increased, while cyclin E expression is decreased, in S100A4-deficient pancreatic tumors in vivo. S100A4-deficient tumors have lower expression of vascular endothelial growth factor, suggesting reduced angiogenesis. Biochemical assays revealed that S100A4 activates Src and focal adhesion kinase (FAK) signaling events, and inhibition of both kinases is required to maximally block the tumorigenic potential of pancreatic cancer cells. These findings support that S100A4 plays an important role in pancreatic cancer progression in vivo and S100A4 promotes tumorigenic phenotypes of pancreatic cancer cells through the Src-FAK mediated dual signaling pathway.

S100 proteins in cancer.

In humans, the S100 protein family is composed of 21 members that exhibit a high degree of structural similarity, but are not functionally interchangeable. This family of proteins modulates cellular responses by functioning both as intracellular Ca(2+) sensors and as extracellular factors. Dysregulated expression of multiple members of the S100 family is a common feature of human cancers, with each type of cancer showing a unique S100 protein profile or signature. Emerging in vivo evidence indicates that the biology of most S100 proteins is complex and multifactorial, and that these proteins actively contribute to tumorigenic processes such as cell proliferation, metastasis, angiogenesis and immune evasion. Drug discovery efforts have identified leads for inhibiting several S100 family members, and two of the identified inhibitors have progressed to clinical trials in patients with cancer. This Review highlights new findings regarding the role of S100 family members in cancer diagnosis and treatment, the contribution of S100 signalling to tumour biology, and the discovery and development of S100 inhibitors for treating cancer.

S100A3 suppression inhibits in vitro and in vivo tumor growth and invasion of human castration-resistant prostate cancer cells.

OBJECTIVE: To investigate the role of S100A3 and the effect of S100A3 inhibition on human castration-resistant prostate cancer (CRPC) cells by using in vitro and in vivo functional assays. MATERIALS AND METHODS: Using human CRPC cells (PC3 and DU145), S100A3 expression levels were assessed by reverse transcription-polymerase chain reaction and Western blot analysis. After S100A3-specific small interfering ribonucleic acid (RNA) treatment, cell viability was determined by Cell Counting Kit-8 assay, and apoptotic cell fractions were evaluated by flow cytometry. The invasive properties of these cells and the expression pattern of matrix metalloproteinases (MMPs) were assessed using transwell migration assays, reverse transcription-polymerase chain reaction, and gelatin zymography. Finally, the in vivo efficacy of S100A3 inhibition on human CRPC cells was investigated using human tumor xenograft models in nude mice. RESULTS: Human CRPC cells showed overexpression of S100A3, and its suppression reduced cell viability owing to apoptotic cell death. Additionally, S100A3 inhibition decreased the invasiveness of human CRPC cells. Moreover, MMP-2 and MMP-9 were downregulated in PC3, whereas only MMP-9 was downregulated in D145 after S100A3 inhibition. In human CRPC xenograft models, we noted a marked reduction in tumor growth in mice injected with S100A3 short hairpin RNA-transfected PC3 and DU145 cells. CONCLUSION: Human CRPC cells showed upregulation of S100A3 expression, and S100A3 inhibition reduced tumor cell viability. S100A3 inhibition reduced invasion capability with downregulation of MMP expression. More importantly, S100A3 inhibition resulted in tumor growth suppression in human CRPC xenograft models, suggesting S100A3 could serve as a novel therapeutic target for the treatment of human CRPC.

Sonic hedgehog-Gli1 signaling pathway regulates the epithelial mesenchymal transition (EMT) by mediating a new target gene, S100A4, in pancreatic cancer cells.

AIMS: The hedgehog signaling pathway plays an important role in EMT of pancreatic cancer cells, but the precise mechanisms remain elusive. Because S100A4 as a key EMT moleculer marker was found to be upregulated upon Gli1 in pancreatic cancer cells, we focused on the relationship between Shh-Gli1 signals and S100 genes family. METHODS: On the base of cDNA microarray data, we investigated regulating mechanism of Gli1 to some members of S100A genes family in pancreatic cancer cell lines firstly. Then, the regulation of Gli1 to S100A4 gene was studied by molecular biology assays and the pro-metastasis effection of Gli1-dependent S100A4 was investigated in vitro. Finally, the expressions of Shh, Gli1, S100A4 and E-cadherin in pancreatic cancer tissues were studied by using immunohistochemistry assays. RESULTS: Five members of the S100 genes family, S100A2, S100A4, S100A6, S100A11, and S100A14 were found to be downregulated significantly upon Gli1 knockdown. Gli1 enhancer prediction combining with in vitro data demonstrated that Gli1 primarily regulates S100A family members via cis-acting elements. Indeed, the data indicate S100A4 and vimentin genes were upregulated significantly by Shh/Gli1-expression increasing and E-cadherin was significantly reduced at the same time. Migration of PC cells was increased significantly in a dose-dependent manner of Gli1 expression (P<0.05) and siS100A4 significantly reversed the response of PC cells induced by L-Shh transduction (P<0.01). CONCLUSION: Our data establish a novel connection between Shh-Gli1 signaling and S100A4 regulation, which imply that S100A4 might be one of the key factors in EMT mediated by Shh-Gli1 signaling in pancreatic cancer.

S100A4 negatively regulates ß-catenin by inducing the Egr-1-PTEN-Akt-GSK3ß degradation pathway.

S100A4, also known as the mts1 gene, has been reported as an invasive and metastatic marker for many types of cancers. S100A4 interacts with various target genes that affect tumor cell metastasis; however, little is known about cellular signaling pathways elicited by S100A4. In the current study, we demonstrate an inhibitory effect of S100A4 on ß-catenin signaling in breast cancer cells. By overexpressing S100A4 in MCF-7, MDA-MB-231 and MDA-MB-453 breast cancer cells, we observed the down-regulation of ß-catenin expression and ß-catenin-dependent TCF/LEF transcriptional activities. The activity of GSK3ß, which phosphorylates ß-catenin and induces proteasomal degradation of ß-catenin, was increased in S100A4-overexpressing cell lines. Blocking Glycogen Synthase Kinase (GSK3ß) activity by lithium chloride or Dvl gene overexpression restored ß-catenin expression. We also found that increased GSK3ß activity was due to decrease in Akt activity resulting from Egr-1-induced phosphatase and tensin homolog (PTEN) expression. S100A4 induced Egr-1 nuclear localization by increasing the association between Egr-1 and importin-7 and this effect was reduced in S100A4 mutants that harbored a defect in nuclear localization signals. Collectively, we verify herein that S100A4 may act as a tumor suppressor in breast cancers by down-regulating the central signaling axis for tumor cell survival.

S100A6 as a potential serum prognostic biomarker and therapeutic target in gastric cancer.

BACKGROUND: Increased expression of S100A6 in many cancer tissues and its association with tumor behavior and patient prognosis were demonstrated, and there are no studies analyzing the serum levels of S100A6 in patients with gastric cancer (GC). AIM: Serum S100A6 levels were investigated as a marker of tumor aggressiveness in patients with GC, and the S100A6 gene was examined as a potential therapeutic target in GC. METHODS: Serum S100A6 levels were detected in 103 GC patients and 72 healthy subjects by ELISA. Clinicopathological features of GC patients were analyzed in correlation to serum S100A6 levels. Two small interfering RNAs against S100A6 (siRNA1-S100A6 and siRNA2-S100A6) were generated and transfected into SGC7901 cells using pSUPER gfp-neo vector, and the effects of S100A6 knockdown on cell proliferation, invasion and apoptosis were evaluated in vitro. The effects of S100A6 silencing on tumor growth and metastasis were evaluated in vivo in a pseudo-metastatic GC nude mouse model. RESULTS: Serum S100A6 levels were significantly higher in GC patients than in healthy controls (P < 0.001). Serum S100A6 levels were significantly correlated with lymph node metastasis, TNM stage, perineural invasion and vascular invasion. Serum S100A6 level was an independent predictor of overall survival. SiRNA-mediated silencing of S100A6 significantly induced apoptosis and decreased proliferation, clone formation and the invasiveness of GC SGC7901 cells in vitro and significantly reduced tumor volume and number in vivo (P < 0.01). CONCLUSION: Serum S100A6 level may serve as a potential prognostic biomarker in GC. Inhibition of S100A6 decreased the metastatic potential of GC cells.

S100 to receptor for advanced glycation end-products binding assay: looking for inhibitors.

Secreted by tumor and stromal cells, S100 proteins exert their biological functions via the interaction with surface receptors. The most described receptor is the receptor for advanced glycation end-products (RAGE), thereby participating in the S100-dependent cell migration, invasion, tumor growth, angiogenesis and metastasis. Several approaches have been described for determining this interaction. Here we describe an easy, specific and highly reproducible ELISA-based method, by optimizing several parameters such as the binding and blocking buffer, interaction time and concentrations, directed to screen chemical and biological inhibitors of this interaction for S100A4, S100A7 and S100P proteins. The efficiency of the protocol was validated by using well described neutralizing agents of the RAGE receptor and of the S100A4 activity. The methodology described here will allow future works with other members of the S100 protein family and their receptors.

S100 protein in breast tumor.

S100 protein is the largest subtribe in calcium binding protein family. According to recent researches, abnormal expression of S100 protein is often related to tumor, including breast tumor. Breast tumor is the most common malignant disease in female with high mortality mainly due to metastasis. Estimating early diagnostic and prognostic markers are helpful to conduct treatment for patients with breast cancer. Accumulating investigations focused on the role of S100 proteins in breast tumor development and metastasis. This paper summarizes the expression situation of S100 proteins in breast tumor as well as its effects on metastasis and prognosis of breast tumor.

EGFRvIII mediates hepatocellular carcinoma cell invasion by promoting S100 calcium binding protein A11 expression.

Epidermal growth factor receptor (EGFR) is frequently aberrantly expressed in cancer, and abnormal signalling downstream of this receptor contributes to tumour growth. EGFR variant III (EGFRvIII) is the most commonly altered form of EGFR and contains a truncated ligand-binding domain. Aberrant signalling downstream of this receptor contributes to tumour invasion. We previously reported that EGFRvIII can promote hepatocellular carcinoma (HCC) invasion. However, little is known concerning the mechanisms underlying EGFRvIII-mediated increases in cell motility and invasion in HCC. In this study, we observed that S100A11 was significantly upregulated in Huh-7 cells that overexpressed EGFRvIII. Moreover, S100A11 expression was elevated in HCC tissue samples (68.6%; 35/51), and this elevation was correlated with EGFRvIII expression (p = 0.0020; n = 20). Furthermore, the overexpression of S100A11 can promote HCC cell invasiveness, whereas siRNA against S100A11 can suppress the invasiveness of HCC cells stably transfected with EGFRvIII. Additionally, STAT3 inhibitors can block S100A11 expression and S100A11 promoter activity in HCC cells with stable overexpression of EGFRvIII. Furthermore, mutation in STATx binding sites could abolish the S1000A11 promoter activity stimulation by EGFRvIII. Taken together, the results demonstrate that the EGFRvIII-STAT3 pathway promotes cell migration and invasion by upregulating S100A11.