Clinical relevance of T1-S, an oncogene-inducible, secreted glycoprotein of the immunoglobulin superfamily, in node-negative breast cancer

The interleukin-1 receptor family

The cytokines IL-1 and IL-18 are key molecules both in the innate and in the adaptive immune response. Their activity is mediated by specific receptors present on the membrane of target cells. It has become apparent that these receptors are members of a larger family of related receptors, most of which are apparently involved in the mechanisms of host defense. Thus, the large Toll/IL-1R (TIR) superfamily encompasses the Ig domain family (IL-1 receptors, IL-18 receptors, and IL-1R-like receptors), the leucine-rich domain family [the Toll-like receptors (TLR) and similar receptors], and a series of TIR domain-containing intracellular adapter molecules. The TIR superfamily is defined by a common intracellular TIR domain, involved in the initiation of signaling. A group of TIR domain-containing adapters (MyD88, TIRAP, TRIF, and TRAM) are differentially recruited to the Toll/IL-1 receptors, contributing to the specificity of signaling. Recent studies have also begun to unravel the mechanisms of negative regulation of the Toll/IL-1 receptors. The orphan receptor TIR8/SIGIRR, a member of TIR superfamily, while unable to initiate signaling, can negatively modulate the TIR-mediated responses. Other negative regulators of the Toll/IL-1R family include T1/ST2, some soluble forms of TLR, and MyD88s. The coordinated positive and negative regulation of the TIR activation ensures the appropriate modulation of the innate and inflammatory responses and avoids the risk of pathological derangement. This chapter will consider in detail the characteristics and functional role of the Ig domain receptor subfamily in the regulation of host defense and their possible role in pathology.

Identification of serum soluble ST2 receptor as a novel heart failure biomarker

BACKGROUND

Using genomic technology, we previously identified an interleukin-1 receptor family member, ST2, as a gene markedly induced by mechanical strain in cardiac myocytes. The soluble receptor form of ST2 is secreted and detectable in human serum. This study tested the hypothesis that soluble ST2 levels in the serum of patients with severe chronic heart failure are increased in patients with neurohormonal activation.

METHODS AND RESULTS

Serum samples, clinical variables, and neurohormone levels from the PRAISE-2 heart failure trial (NYHA functional class III-IV; end point, mortality or transplantation) were analyzed. ST2 serum measurements were performed with ELISA on samples from 161 patients obtained at trial enrollment and from 139 of the same patients obtained 2 weeks after trial enrollment. Baseline ST2 levels were correlated with baseline B-type natriuretic peptide (BNP) levels (r=0.36, P<0.0001), baseline proatrial natriuretic peptide (ProANP) levels (r=0.36, P<0.0001), and baseline norepinephrine levels (r=0.39, P<0.0001). The change in ST2 was significant as a univariate predictor of subsequent mortality or transplantation (P=0.048), as was baseline BNP (P<0.0001) and baseline ProANP (P<0.0001). In multivariate models including BNP and ProANP, the change in ST2 remained significant as a predictor of mortality or transplantation independent of BNP and ProANP.

CONCLUSIONS

Serum soluble ST2 is a novel biomarker for neurohormonal activation in patients with heart failure. In patients with severe chronic NYHA class III to IV heart failure, the change in ST2 levels is an independent predictor of subsequent mortality or transplantation.

The effect of ST2 gene product on anchorage-independent growth of a glioblastoma cell line, T98G

The ST2 gene, which is specifically induced by growth stimulation in fibroblasts, encodes interleukin-1 receptor-related proteins and is widely expressed in hematopoietic, helper T, and various cancer cells. However, the physiological as well as pathological functions of the ST2 gene products are not yet fully understood. In this study, we analyzed the expression of the ST2 gene in human glioma cell lines and human brain tumor samples with real-time polymerase chain reaction method, the results of which revealed that the expression level of the ST2 gene in glioma cell lines and glioblastoma samples is significantly lower than that in a fibroblastic cell line, TM12, and benign brain tumors, suggesting the reverse relationship between malignancy and ST2 expression. As we could not detect the soluble ST2 protein in the culture fluid of the T98G glioblastic cell line by ELISA, we established stable transformants of T98G that continuously produce and secrete the ST2 protein, in order to study the effect of the ST2 protein on malignancy. Although we could not detect a remarkable difference in proliferation between transformants and control cells in conventional tissue culture dishes, the efficiency of colony formation in soft agar was significantly decreased in the case of cells that continuously produce the ST2 protein. Furthermore, inhibition of colony formation in soft agar was observed in wild-type T98G cells when purified soluble ST2 protein was added to the culture, in a dose-dependent manner. Taken together, the results suggest that the expression of ST2 suppressed the anchorage-independent growth and malignancy.

Expression and regulation of ST2, an interleukin-1 receptor family member, in cardiomyocytes and myocardial infarction

BACKGROUND

We identified an interleukin-1 receptor family member, ST2, as a gene markedly induced by mechanical strain in cardiac myocytes and hypothesized that ST2 participates in the acute myocardial response to stress and injury.

METHODS AND RESULTS

ST2 mRNA was induced in cardiac myocytes by mechanical strain (4.7+/-0.9-fold) and interleukin-1beta (2.0+/-0.2-fold). Promoter analysis revealed that the proximal and not the distal promoter of ST2 is responsible for transcriptional activation in cardiac myocytes by strain and interleukin-1beta. In mice subjected to coronary artery ligation, serum ST2 was transiently increased compared with unoperated controls (20.8+/-4.4 versus 0.8+/-0.8 ng/mL, P<0.05). Soluble ST2 levels were increased in the serum of human patients (N=69) 1 day after myocardial infarction and correlated positively with creatine kinase (r=0.41, P<0.001) and negatively with ejection fraction (P=0.02).

CONCLUSIONS

These data identify ST2 release in response to myocardial infarction and suggest a role for this innate immune receptor in myocardial injury.

Identification of two distinct subpopulations of Leishmania major-specific T helper 2 cells

It is widely accepted that a strong Th2 response is responsible for nonhealing Leishmania major infections in BALB/c mice. This Th2 response has been thoroughly documented by measuring the levels of Th2 cytokines produced by CD4(+) T cells present in the lymphoid organs by enzyme-linked immunosorbent assay and PCR. However, the cytokine profile of L. major-specific Th2 cells has never been determined. In this study, we used the recently described Th2 marker T1/ST2 to characterize Th2 cells during the course of nonhealing L. major infection. We analyzed the intracellular cytokine profile of CD4(+) T1/ST2(+) T cells and showed that they clearly displayed a Th2 phenotype, as they expressed interleukin 4 (IL-4), IL-10, and IL-5. In addition, we detected another population of Th2 cells among the CD4(+) T1/ST2(-) T cells that expressed IL-4 and IL-10 but excluded IL-5. In summary, we show here that two type 2 subpopulations are present in the lymphoid organs of L. major-infected BALB/c mice; Th2 cells from both subsets expressed IL-4 and IL-10, but they could be distinguished by their expression of IL-5 and T1/ST2.

Inhibition of proliferation and expression of T1 and cyclin D1 genes by thyroid hormone in mammary epithelial cells

The relationship between thyroid hormone (triiodothyronine, T(3)) and breast cancer is unclear. We studied the effect of the c-erbA/TR alpha proto-oncogene encoding a functional T(3) receptor (TR alpha 1), of its ligand T(3), and of its retroviral, mutated counterpart, the v-erbA oncogene, on the proliferation capacity of nontumorigenic mammary epithelial cells (EpH4). We found that EpH4 cells expressing ectopically TR (EpH4 + TR alpha 1) or v-erbA (EpH4 + v-erbA) proliferated faster than parental EpH4 cells that contained low levels of endogenous TR. T(3) inhibited DNA synthesis and proliferation in EpH4 + TR alpha 1 cells but not EpH4 or EpH4 + v-erbA cells. The study of cell-cycle genes showed that T(3) decreased cyclin D1 RNA and protein levels in EpH4 + TR alpha 1 cells. In addition, T(3) downregulated the expression of T1, a gene that is overexpressed in human breast adenocarcinomas and is induced by mitogens, serum, and several oncogenes and cytokines. Inhibition of the T1 gene by T(3) required both de novo mRNA and protein synthesis. Furthermore, T(3) abolished the induction of T1 by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate and inhibited the activity of an activation protein 1-dependent promoter (-73-Col-CAT) in EpH4 + TR alpha 1 cells, suggesting that interference with activation protein 1 transcription factor plays a part in the inhibition of the T1 gene. Our results showed that T(3) reduced the proliferation of mammary epithelial cells and inhibited the expression of cyclin D1 and T1 genes.

IL-1 and IL-18 receptors, and their extended family

The cytokines IL-1 and IL-18 are key molecules in both the innate and the adaptive immune response. Recently, important insights have been gained into the regulation of their functions. Moreover, it has become apparent that they are members of a larger family of related receptors, some of which can also be shown to contribute to host defense.