Differential expression of S100 calcium-binding proteins in epidermoid cysts, branchial cysts, craniopharyngiomas and cholesteatomas

The Tilapia Cyst Tissue Enclosing the Proliferating Myxobolus bejeranoi Parasite Exhibits Cornified Structure and Immune Barrier Function

Myxozoa, a unique group of obligate endoparasites within the phylum Cnidaria, can cause emerging diseases in wild and cultured fish populations. Recently, the myxozoan Myxobolus bejeranoi has been identified as a prevalent pathogen infecting the gills of cultured hybrid tilapia, leading to systemic immune suppression and considerable mortality. Here, we employed a proteomic approach to examine the impact of M. bejeranoi infection on fish gills, focusing on the structure of the granulomata, or cyst, formed around the proliferating parasite to prevent its spread to surrounding tissue. Enrichment analysis showed increased immune response and oxidative stress in infected gill tissue, most markedly in the cyst's wall. The intense immune reaction included a consortium of endopeptidase inhibitors, potentially combating the myxozoan arsenal of secreted proteases. Analysis of the cyst's proteome and histology staining indicated that keratin intermediate filaments contribute to its structural rigidity. Moreover, we uncovered skin-specific proteins, including a grainyhead-like transcription factor and a teleost-specific S100 calcium-binding protein that may play a role in epithelial morphogenesis and cysts formation. These findings deepen our understanding of the proteomic elements that grant the cyst its distinctive nature at the critical interface between the fish host and myxozoan parasite.

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.

Investigating the Protein Signature of Adamantinomatous Craniopharyngioma Pediatric Brain Tumor Tissue: Towards the Comprehension of Its Aggressive Behavior

Although histologically benign, adamantinomatous craniopharyngioma (AC) pediatric brain tumor is a locally aggressive disease that frequently determines symptoms and hormonal dysfunctions related to the mass effect on the surrounding structures. Another typical feature of this benign neoplasm is the presence of voluminous liquid cysts frequently associated with the solid component. Even if studies have been devoted to the proteomic characterization of the tumor intracystic fluid, poor explorations have been performed on its solid part, principally investigated by transcriptomics technologies. In the present study, seven specimens of AC whole tumor tissue have been analyzed by LC-MS for a preliminary assessment of the proteomic profile by a top-down/bottom-up integrated approach. Thymosin beta 4, ubiquitin, calmodulin, S100 proteins, prothymosin α isoform 2, alpha-defensins 1-4, and fragments largely belonging to vimentin, hemoglobin, and glial fibrillary acidic protein characterized the intact proteome. The identification of alpha-defensins, formerly characterized in AC intracystic fluid, reinforces the hypothesis of a role for inflammation in tumor pathogenesis. A total number of 1798 unique elements were identified by a bottom-up approach with a special focus on the 433 proteins commonly characterized in the 85.7% of the samples analyzed. Their gene ontology classification evidenced the involvement of the adherence system, intermediate filaments, and actin cytoskeleton in tumor pathogenesis and of elements part of the Wnt, FGF, and EGFR signaling pathways. In addition, proteins involved in calcium modulation, innate immunity, inflammation, CCKR and integrin signaling, and gonadotropin-releasing hormone receptor pathways were also outlined. Further than confirming proteomic data previously obtained on AC intracystic fluid, these results offer a preliminary overview of the AC whole tissue protein phenotype, adding new hints towards the comprehension of this still obscure pediatric brain tumor.

Elevated S100A6 (Calcyclin) enhances tumorigenesis and suppresses CXCL14-induced apoptosis in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is often resistant to existing therapy. We found elevated S100A6 levels in ccRCC tissues, associated with higher grade pathological features and clinical stages in ccRCC patients. Knockdown of S100A6 inhibited cell proliferation in vitro and tumor growth in vivo. Gene expression profiling suggests a novel function of S100A6 in suppressing apoptosis, as well as a relationship between S100A6 and CXCL14, a pro-inflammatory chemokine. We suggest that the S100A6/CXCL14 signaling pathway is a potential therapeutic target in ccRCC.

High-level S100A6 promotes metastasis and predicts the outcome of T1-T2 stage in clear cell renal cell carcinoma

S100A6 (calcyclin), functions in cell cycle progression and differentiation, has been reported to promote the tumorigenesis and malignancy of many types of cancers. Clear cell renal cell carcinoma (ccRCC) is the most common subtype of RCC, lacking both promising prognostic markers and effective therapeutic targets. In our previous study, we have found the elevated S100A6 in the ccRCC tumor tissues, and the differentially expressed genes determined by microarray analysis were found to be strongly related to tumor metastasis after S100A6 knockdown and overexpression in the ccRCC cell line 786-O. The mRNA expression of S100A6 detected by RT-PCR in 6 cell lines and 174 tumor tissues, including 58 metastatic ccRCC and 116 clinicopathological features paired non-metastatic ccRCC (1:2), indicated S100A6 was elevated in the metastatic cells and tumor tissues. The protein expression was consistent with mRNA expression. The biological function of S100A6 in promoting metastasis was determined through overexpression and knockdown of S100A6 in the ccRCC cell lines 786-O, caki-1, and ACHN. In the scratch wound migration assay as well as migration and invasion assays, S100A6 knockdown significantly suppressed the migratory and invasive abilities of tumor cells, whereas overexpression enhanced the malignancy. Further research with the follow-up data of 129 ccRCC patients were analyzed by the Cox regression and survival analysis. The expression of S100A6 was up-regulated in metastatic ccRCC cells. In the metastatic tumor tissues, the expression of S100A6 was also higher than in the non-metastatic tissues. High S100A6 expression might be crucial to promote metastasis in ccRCC by enhancing the ability of tumor cells migration and invasion. In addition, the quantitative mRNA expression of S100A6 in the tumor tissues was an independent risk factor and might be used as a prognostic marker for the metastatic risk of the localized T1-T2 stage ccRCC.

Large-scale proteomics differentiates cholesteatoma from surrounding tissues and identifies novel proteins related to the pathogenesis

Cholesteatoma is the growth of keratinizing squamous epithelium in the middle ear. It is associated with severe complications and has a poorly understood etiopathogenesis. Here, we present the results from extensive bioinformatics analyses of the first large-scale proteomic investigation of cholesteatoma. The purpose of this study was to take an unbiased approach to identifying alterations in protein expression and in biological processes, in order to explain the characteristic phenotype of this skin-derived tumor. Five different human tissue types (cholesteatoma, neck of cholesteatoma, tympanic membrane, external auditory canal skin, and middle ear mucosa) were analyzed. More than 2,400 unique proteins were identified using nanoLC-MS/MS based proteomics (data deposited to the ProteomeXchange), and 295 proteins were found to be differentially regulated in cholesteatoma. Validation analyses were performed by SRM mass spectrometry. Proteins found to be up- or down-regulated in cholesteatoma were analyzed using Ingenuity Pathway Analysis and clustered into functional groups, for which activation state and associations to disease processes were predicted. Cholesteatoma contained high levels of pro-inflammatory S100 proteins, such as S100A7A and S100A7. Several proteases, such as ELANE, were up-regulated, whereas extracellular matrix proteins, such as COL18A1 and NID2, were under-represented. This may lead to alterations in integrity and differentiation of the tissue (as suggested by the up-regulation of KRT4 in the cholesteatoma). The presented data on the differential protein composition in cholesteatoma corroborate previous studies, highlight novel protein functionalities involved in the pathogenesis, and identify new areas for targeted research that hold therapeutic potential for the disease.

Galectin-1, -3, -7 expressions in congenital and acquired pediatric cholesteatomas compared to external auditory canal skin

OBJECTIVES

There is a classical distinction based on clinical criteria between acquired and congenital cholesteatomas. To determine if these two types of lesions show different immunohistochemical features, we have studied the expression patterns of three distinctive galectins (animal lectins implied especially in cellular proliferation and apoptosis) in both types of cholesteatomas and compared it to their expression patterns in external auditory canal skin.

METHODS

Our study is based on nine acquired and eight congenital cholesteatomas, obtained from children during ear surgery. Six specimens of normal adult auditory meatal skin served as control. Specimens were analyzed by immunohistochemistry using monoclonal antibodies with galectin-1 and galectin-3, and a polyclonal antibody with galectin-7.

RESULTS

We did not observe any differences in the galectin distribution pattern between congenital and acquired pediatric cholesteatomas. Compared to the control group, cholesteatomas present some particular features. There was no expression of galectin-1 and a lower expression of galectin-3 in the epithelium. Furthermore, we observed a preferentially nuclear distribution of galectin-7 in cholesteatomas, whereas it is essentially cytoplasmic in the control group.

CONCLUSION

The data reported in this study suggest, on the basis of a lesser marked galectin-3 in cholesteatomas epithelium compared with an external auditory canal skin, that an immature keratinocytes population is at the origin of these lesions and that galectin-3 and galectin-7 play a part in the capacity as apoptosis modulators. Our study does not establish a difference in the galectin expressions of congenital and acquired cholesteatomas, but it constitutes however an additional argument in favor of the "undifferentiated" origin of keratinocytes in cholesteatomas.

Solution structure of S100A1 bound to the CapZ peptide (TRTK12)

As is typical for S100-target protein interactions, a Ca 2+-dependent conformational change in S100A1 is required to bind to a 12-residue peptide (TRTK12) derived from the actin-capping protein CapZ. In addition, the Ca 2+-binding affinity of S100A1 is found to be tightened (greater than threefold) when TRTK12 is bound. To examine the biophysical basis for these observations, we determined the solution NMR structure of TRTK12 in a complex with Ca 2+-loaded S100A1. When bound to S100A1, TRTK12 forms an amphipathic helix (residues N6 to S12) with several favorable hydrophobic interactions observed between W7, I10, and L11 of the peptide and a well-defined hydrophobic binding pocket in S100A1 that is only present in the Ca 2+-bound state. Next, the structure of S100A1-TRTK12 was compared to that of another S100A1-target complex (i.e., S100A1-RyRP12), which illustrated how the binding pocket in Ca 2+-S100A1 can accommodate peptide targets with varying amino acid sequences. Similarities and differences were observed when the structures of S100A1-TRTK12 and S100B-TRTK12 were compared, providing insights regarding how more than one S100 protein can interact with the same peptide target. Such comparisons, including those with other S100-target and S100-drug complexes, provide the basis for designing novel small-molecule inhibitors that could be specific for blocking one or more S100-target protein interactions.

S100A1: Structure, Function, and Therapeutic Potential

S100A1 is a member of the S100 family of calcium-binding proteins. As with most S100 proteins, S100A1 undergoes a large conformational change upon binding calcium as necessary to interact with numerous protein targets. Targets of S100A1 include proteins involved in calcium signaling (ryanidine receptors 1 & 2, Serca2a, phopholamban), neurotransmitter release (synapsins I & II), cytoskeletal and filament associated proteins (CapZ, microtubules, intermediate filaments, tau, mocrofilaments, desmin, tubulin, F-actin, titin, and the glial fibrillary acidic protein GFAP), transcription factors and their regulators (e.g. myoD, p53), enzymes (e.g. aldolase, phosphoglucomutase, malate dehydrogenase, glycogen phosphorylase, photoreceptor guanyl cyclases, adenylate cyclases, glyceraldehydes-3-phosphate dehydrogenase, twitchin kinase, Ndr kinase, and F1 ATP synthase), and other Ca2+-activated proteins (annexins V & VI, S100B, S100A4, S100P, and other S100 proteins). There is also a growing interest in developing inhibitors of S100A1 since they may be beneficial for treating a variety of human diseases including neurological diseases, diabetes mellitus, heart failure, and several types of cancer. The absence of significant phenotypes in S100A1 knockout mice provides some early indication that an S100A1 antagonist could have minimal side effects in normal tissues. However, development of S100A1-mediated therapies is complicated by S100A1's unusual ability to function as both an intracellular signaling molecule and as a secreted protein. Additionally, many S100A1 protein targets have only recently been identified, and so fully characterizing both these S100A1-target complexes and their resulting functions is a necessary prerequisite.

Cancer predisposition in mice deficient for the metastasis-associated Mts1(S100A4) gene

Metastasis-promoting Mts1(S100A4) protein belongs to the S100 family of Ca(2+)-binding proteins. A mouse strain with a germ-line inactivation of the S100A4 gene was generated. The mice were viable and did not display developmental abnormalities in the postnatal period. However, an abnormal sex ratio was observed in the litters with the S100A4-/- genotype, raising the possibility of a certain level of embryonic lethality in this strain. In all, 10% of 10-14-month-old S100A4-null animals developed tumors. This is a characteristic feature of mouse strains with inactivated tumor suppressor genes. Spontaneous tumors of S100A4-/- mice were p53 positive. Recently, we have shown that S100A4 interacts with p53 tumor suppressor protein and induces apoptosis. We proposed that impairment of this interaction could affect the apoptosis-promoting function of p53 that is involved in its tumor suppressor activity. The frequency of apoptosis in the spleen of S100A4-/- animals after whole-body gamma-irradiation was reduced compared to the wild-type animals. The same was true for the transcriptional activation of the p53 target genes - waf/p21/cip1 and bax. Taken together, these observations indicate that spontaneous tumors in S100A4-/- mice are a result of functional destabilization of p53 tumor suppressor gene.