S100: a multigenic family of calcium-modulated proteins of the EF-hand type with intracellular and extracellular functional roles.

The S100 protein family: History, function, and expression

Early studies demonstrating the ability of dietary carotenes to prevent infections have left open the possibility that the action of these carotenoids may be through their prior conversion to vitamin A. Subsequent studies to demonstrate the specific action of dietary carotenoids have used carotenoids without provitamin A activity such as lutein, canthaxanthin, lycopene and astaxanthin. In fact, these nonprovitamin A carotenoids were as active, and at times more active, than beta-carotene in enhancing cell-mediated and humoral immune response in animals and humans. Another approach to study the possible specific role of dietary carotenoids has used animals that are inefficient converters of carotenoids to vitamin A, for example the domestic cat. Results have similarly shown immuno-enhancement by nonprovitamin A carotenoids, based either on the relative activity or on the type of immune response affected compared to beta-carotene. Certain carotenoids, acting as antioxidants, can potentially reduce the toxic effects of reactive oxygen species (ROS). These ROS, and therefore carotenoids, have been implicated in the etiology of diseases such as cancer, cardiovascular and neurodegenerative diseases and aging. Recent studies on the role of carotenoids in gene regulation, apoptosis and angiogenesis have advanced our knowledge on the possible mechanism by which carotenoids regulate immune function and cancer.

Carotenoid Action on the Immune Response

At present, six groups of chronic pulmonary hypertension (PH) are described. Among these, group 1 (and 1') comprises a group of diverse diseases termed pulmonary arterial hypertension (PAH) that have several pathophysiological, histological, and prognostic features in common. PAH is a particularly severe and progressive form of PH that frequently leads to right heart failure and premature death. The diagnosis of PAH must include a series of defined clinical parameters, which extend beyond mere elevations in pulmonary arterial pressures and include precapillary PH, pulmonary hypertensive arteriopathy (usually with plexiform lesions), slow clinical onset (months or years), and a chronic time course (years) characterized by progressive deterioration. What appears to distinguish PAH from other forms of PH is the severity of the arteriopathy observed, the defining characteristic of which is "plexogenic arteriopathy." The pathogenesis of this arteriopathy remains unclear despite intense investigation in a variety of animal model systems. The most commonly used animal models ("classic" models) are rodents exposed to either hypoxia or monocrotaline. Newer models, which involve modification of classic approaches, have been developed that exhibit more severe PH and vascular lesions, which include neointimal proliferation and occlusion of small vessels. In addition, genetically manipulated mice have been generated that have provided insight into the role of specific molecules in the pulmonary hypertensive process. Unfortunately, at present, there is no perfect preclinical model that completely recapitulates human PAH. All models, however, have provided and will continue to provide invaluable insight into the numerous pathways that contribute to the development and maintenance of PH. Use of both classic and newly developed animal models will allow continued rigorous testing of new hypotheses regarding pathogenesis and treatment. This review highlights progress that has been made in animal modeling of this important human condition.

Animal models of pulmonary arterial hypertension: the hope for etiological discovery and pharmacological cure

Functional roles of S100 proteins, calcium-binding proteins of the EF-hand type

The cDNA coding for mouse fibroblast tropomyosin isoform 2 (TM2) was placed into a bacterial expression vector to produce a fusion protein containing glutathione-S-transferase (GST) and TM2 (GST/TM2). Glutathione-Sepharose beads bearing GST/TM2 were incubated with [35S]methionine-labeled NIH 3T3 cell extracts and the materials bound to the fusion proteins were analyzed to identify proteins that interact with TM2. A protein of 10 kD was found to bind to GST/TM2, but not to GST. The binding of the 10-kD protein to GST/TM2 was dependent on the presence of Ca2+ and inhibited by molar excess of free TM2 in a competition assay. The 10-kD protein-binding site was mapped to the region spanning residues 39-107 on TM2 by using several COOH-terminal and NH2-terminal truncation mutants of TM2. The 10-kD protein was isolated from an extract of NIH 3T3 cells transformed by v-Ha-ras by affinity chromatography on a GST/TM2 truncation mutant followed by SDS-PAGE and electroelution. Partial amino acid sequence analysis of the purified 10-kD protein, two-dimensional polyacrylamide gel analysis and a binding experiment revealed that the 10-kD protein was identical to a calcium-binding protein derived from mRNA named pEL98 or 18A2 that is homologous to S100 protein. Immunoblot analysis of the distribution of the 10-kD protein in Triton-soluble and -insoluble fractions of NIH 3T3 cells revealed that some of the 10-kD protein was associated with the Triton-insoluble cytoskeletal residue in a Ca(2+)-dependent manner. Furthermore, immunofluorescent staining of NIH 3T3 cells showed that some of the 10-kD protein colocalized with nonmuscle TMs in microfilament bundles. These results suggest that some of the pEL98 protein interacts with microfilament-associated nonmuscle TMs in NIH 3T3 cells.

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Binding of pEL98 protein, an S100-related calcium-binding protein, to nonmuscle tropomyosin.

The S100A4 gene (also known as pEL98/mts1/p9Ka/18A2/42A/calvasculin /FSP1/CAPL) encoding an S100-related calcium-binding protein is implied to be involved in the invasion and metastasis of murine tumor cells. In the present study, the expression of S100A4 in human colorectal adenocarcinoma cell lines (SW837, LoVo, DLD-1, HT-29, SW480, SW620, WiDr, and Colo201) and surgically resected neoplastic tissues was examined to investigate whether S100A4 plays a role in the invasion and metastasis of human tumor cells. Northern blot analysis using total RNA isolated from the adenocarcinoma cell lines revealed that five of the eight cell lines expressed substantial amounts of S100A4 mRNA. Normal colon fibroblasts (CCD-18Co) expressed little of the RNA. Using surgically resected specimens, it seemed that the amount of S100A4 mRNA in adenomas was nearly equal to that in normal colonic mucosa, whereas adenocarcinomas expressed a significantly higher amount of the RNA than did the adjacent normal colonic mucosa. Immunohistochemical analysis using formalin-fixed paraffin-embedded surgical specimens and monoclonal anti-S100A4 antibody demonstrated that none of 12 adenoma specimens were immunopositive, whereas 8 of 18 (44%) focal carcinomas in carcinoma in adenoma specimens and 50 of 53 (94%) adenocarcinoma specimens were immunopositive. Interestingly, the incidence of immunopositive cells increased according to the depth of invasion, and nearly all of the carcinoma cells in 14 metastases in the liver were positive. These results suggest that S100A4 may be involved in the progression and the metastatic process of human colorectal neoplastic cells.

https://clincancerres.aacrjournals.org/content/clincanres/3/12/2309.full.pdf

Increased expression of S100A4, a metastasis-associated gene, in human colorectal adenocarcinomas.

The effect of beta-carotene on tumor immunity was examined with the use of a syngeneic murine tumor system. Oral administration of beta-carotene (120 micrograms/mouse/day) for 9 days from day 1 to the BALB/c mice inoculated sc with 10(7) syngeneic BALB/c Meth A fibrosarcoma cells (Meth A) led to a remarkable rejection against rechallenged Meth A implanted sc on day 10. The growth of Meth 1 fibrosarcoma (Meth 1), another syngeneic tumor of BALB/c origin, as a rechallenge tumor was unaffected by treatment with beta-carotene, thereby suggesting that beta-carotene may augment tumor rejection specific to tumor-specific antigens. Winn assay revealed that the suppressive effect on tumor growth of immune lymph node cells obtained from Meth A-inoculated beta-carotene-treated mice on day 12 was enhanced dose dependently. Primary effector cells responsible for the augmented rejection are Thy-1-positive, Lyt-1-negative, and Lyt-2-positive lymphocytes, presumably cytotoxic T-lymphocytes.

Augmentation of Tumor Immunity Against Syngeneic Tumors in Mice by β-Carotene

https://www.jbc.org/content/277/29/26396.full.pdf

Hideya Endo

Papers

Binding of pEL98 protein, an S100-related calcium-binding protein, to nonmuscle tropomyosin.

Increased expression of S100A4, a metastasis-associated gene, in human colorectal adenocarcinomas.

Augmentation of Tumor Immunity Against Syngeneic Tumors in Mice by β-Carotene

Methionine aminopeptidase 2 is a new target for the metastasis-associated protein, S100A4.

A nitrofuran derivative, a new inducing agent for the phage development in lysogenic Escherichia coli