Expression of the Hermes-1 (CD44) and ICAM-1 (CD54) molecule on the surface of thyroid cells from patients with Graves' disease

Potentiating Therapeutic Effects of Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subset of breast cancer with aggressive characteristics and few therapeutic options. The lack of an appropriate therapeutic target is a challenging issue in treating TNBC. Although a high level expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis among patients with TNBC, targeted anti-EGFR therapies have demonstrated limited efficacy for TNBC treatment in both clinical and preclinical settings. However, with the advantage of a number of clinically approved EGFR inhibitors (EGFRis), combination strategies have been explored as a promising approach to overcome the intrinsic resistance of TNBC to EGFRis. In this review, we analyzed the literature on the combination of EGFRis with other molecularly targeted therapeutics or conventional chemotherapeutics to understand the current knowledge and to provide potential therapeutic options for TNBC treatment.

Key gene co-expression modules and functional pathways involved in the pathogenesis of Graves' disease

Graves' disease (GD) is a common autoimmune thyroid disease characterized by positive thyroid stimulating hormone receptor antibody. To better understand its molecular pathogenesis, we adopted the weighted gene co-expression network analysis to reveal co-expression modules of key genes involved in the pathogenesis of GD, protein-protein interaction network analysis to identify the hub genes related to GD development and functional analyses to explore their possible functions. Our results showed that 1) a total of 2667 differentially expressed genes in our microarray study and 16 different gene co-expression modules were associated with GD, and 2) the most significant module was associated with the percentage of macrophages, T follicular helper cells and CD4⁺ memory T cells and mainly enriched in immune regulation and immune response. Overall, our study reveals several key gene co-expression modules and functional pathways involved in GD, which provides some novel insights into the pathogenesis of GD.

Hypoxia regulates CD44 and its variant isoforms through HIF-1α in triple negative breast cancer

BACKGROUND

The CD44 transmembrane glycoproteins play multifaceted roles in tumor progression and metastasis. CD44 expression has also been associated with stem-like breast cancer cells. Hypoxia commonly occurs in tumors and is a major cause of radiation and chemo-resistance. Hypoxia is known to inhibit differentiation and facilitates invasion and metastasis. Here we have investigated the effect of hypoxia on CD44 and two of its isoforms in MDA-MB-231 and SUM-149 triple negative human breast cancer cells and MDA-MB-231 tumors using imaging and molecular characterization.

METHODS AND FINDINGS

The roles of hypoxia and hypoxia inducible factor (HIF) in regulating the expression of CD44 and its variant isoforms (CD44v6, CD44v7/8) were investigated in human breast cancer cells, by quantitative real-time polymerase chain reaction (qRT-PCR) to determine mRNA levels, and fluorescence associated cell sorting (FACS) to determine cell surface expression of CD44, under normoxic and hypoxic conditions. In vivo imaging studies with tumor xenografts derived from MDA-MD-231 cells engineered to express tdTomato red fluorescence protein under regulation of hypoxia response elements identified co-localization between hypoxic fluorescent regions and increased concentration of (125)I-radiolabeled CD44 antibody.

CONCLUSIONS

Our data identified HIF-1α as a regulator of CD44 that increased the number of CD44 molecules and the percentage of CD44 positive cells expressing variant exons v6 and v7/8 in breast cancer cells under hypoxic conditions. Data from these cell studies were further supported by in vivo observations that hypoxic tumor regions contained cells with a higher concentration of CD44 expression.

Lymphocyte homing in xenotransplanted human thyroid tissue can be inhibited by LFA-1 and ICAM-1 antibodies

OBJECTIVES

Homing of lymphocytes is an important factor with respect to the initiation of the autoimmune process in Graves' disease (GD). As previously shown, human lymphocytes, particularly of intrathyroidal origin, derived from patients with GD, are able to migrate into normal xenotransplanted thyroid tissue and induce functional and histological changes. The aim of this study was to investigate the effect of LFA-1 and ICAM-1 antibodies on the homing of lymphocytes of different origin into xenografted human thyroid tissue.

METHODS

Eighty-five nude mice bearing 8-week-old xenografts of normal human thyroid tissue were treated twice with anti-CD 54 (anti-ICAM-1), anti-CD 11a (anti-LFA-1), a combination of both, or, serving as controls, iso-antibodies without specific binding capacity or saline. Thereafter, intrathyroidal (ITL) or peripheral blood lymphocytes (PBL) obtained from 4 patients with GD or saline were injected into the animals (i.v., 0.2 mL, 10(6) cells). After 48 hours the mice were sacrificed and transplants as well as mice thyroids were examined by immunohistochemical staining with Ki67, CD3, HLA-II (DAKO, Hamburg), IgG, CD44, ICAM-1, and VCAM-1 (Immunotech, Hamburg).

RESULTS

Pretreatment with anti-ICAM-1 and anti-LFA-1 decreased lymphocyte homing (CD3-staining), and expression of HLA-II, IgG, CD44, and VCAM-1 in the transplants.

CONCLUSION

Our data show that [ICAM-1/LFA-1 stimulated (induced)] lymphocyte homing and subsequently thyrocyte proliferation are inhibited by ICAM-1 and LFA-1 antibodies in xenotransplanted thyroid tissue. This suggests that ICAM1 and LFA-1 play an important role in the early steps of autoimmune thyroid disease. The inhibition/suppression of ICAM-1 and LFA-1 interaction by respective antibodies, as demonstrated in the present study, may provide a new concept for prophylaxis and therapy.

Expression of intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 and homing factor CD44 after engraftment of Graves' lymphocytes in xenotransplanted human thyroid tissue in athymic nude mice

The expression of adhesion molecules on thyrocytes and endothelium cells plays an important role in the pathogenesis of Graves' disease (GD). The intercellular adhesion molecule-1 (ICAM-1), the vascular cell adhesion molecule-1 (VCAM-1), and the homing receptor CD44 are responsible for the specific migration of lymphocytes in autoimmune thyroid diseases (AITD) (homing). Eight weeks after transplantation of thyroid tissue from 26 patients with nonautoimmune thyroid disease (nontoxic nodular goiter [NTG]) into nude mice, peripheral (PBL) and intrathyroidal lymphocytes (ITL) from 14 patients with NTG and 12 patients with GD were grafted into the animals. Two days after lymphocyte engraftment, the thyroid transplants were examined histologically (HE) and immunohistologically stained with monoclonal antibodies directed against ICAM-1, VCAM-1, and CD44. After injection of GD lymphocytes, thyroid transplants expressed significantly more ICAM-1, VCAM-1, and CD44 than after injection of NTG lymphocytes. This expression was even more pronounced after grafting of GD intrathyroidal lymphocytes. Our data demonstrate that only GD lymphocytes induce the expression of adhesion molecules and homing factor CD44, both of which play an important role in the migration of lymphocytes and induction of the autoimmune process.

Thyrotropin modulates interferon-gamma-mediated intercellular adhesion molecule-1 gene expression by inhibiting Janus kinase-1 and signal transducer and activator of transcription-1 activation in thyroid cells

TSH is known as an important hormone that plays the major role not only in the maintenance of normal physiology but also in the regulation of immunomodulatory gene expression in thyrocytes. The adhesion molecule intercellular adhesion molecule-1 (ICAM-1) was identified as one of the proteins that are abnormally expressed in the thyroid gland during autoimmune thyroid diseases. In this study we found that TSH inhibits interferon-gamma (IFNgamma)-mediated expression of the ICAM-1 gene, and we investigated the involved mechanisms in rat FRTL-5 thyroid cells. After exposure to IFNgamma, ICAM-1 expression is positively regulated at the level of transcription. This effect occurs via the IFNgamma-activated site (GAS) element in the ICAM-1 promoter as a consequence of the activation of STAT1 (signal transducer and activator of transcription-1), but not of STAT3. On the other hand, after exposure to TSH plus IFNgamma, ICAM-1 transcription is negatively modulated. We found that this inhibitory effect of TSH also occurs via the GAS element. Electrophoretic mobility shift assays confirmed that the IFNgamma-induced DNA-binding activities of STAT1 were reduced by TSH. Furthermore, our results showed that the inhibitory effect of TSH on IFNgamma signaling is caused by inhibition of tyrosine phosphorylation on STAT1, Janus kinase-1 (Jak1), and IFNgamma receptor a, but not Jak2. In conclusion, we have identified a novel mechanism in which TSH modulates the IFNgamma-mediated Jak/STAT signaling pathway through the inhibition of Jak1 and STAT1.

Hormone-dependent regulation of intercellular adhesion molecule-1 gene expression: cloning and analysis of 5'-regulatory region of rat intercellular adhesion molecule-1 gene in FRTL-5 rat thyroid cells

Intercellular adhesion molecule-1 (ICAM-1) has been suggested to play an important role in the perpetuation of autoimmune thyroid disease. To clarify the regulation of ICAM-1 gene in thyroid cells, we investigated ICAM-1 expression in the FRTL-5 thyroid cell model and defined several elements in the 5'-regulatory region that are important for transcriptional regulation of the rat ICAM-1 gene. Cells maintained in medium with 5% serum but without hydrocortisone, insulin, and thyrotropin (TSH) express the highest levels of ICAM-1 RNA. TSH/forskolin downregulate ICAM-1 RNA levels independent of the presence or absence of hydrocortisone or insulin. Moreover, TSH/forskolin decrease ICAM-1 RNA levels that are maximally induced by two cytokines: 100 ng/mL tumor necrosis factor-alpha (TNF-alpha) or 100 U/ml interferon-gamma (IFN-gamma). The effect of TSH/forskolin, as well as TNF-alpha and IFN-gamma, on ICAM-1 RNA levels is transcriptional. Thus, we cloned a 1.8-kb fragment of the 5'-flanking region of the rat ICAM-1 gene, upstream of the translational start site, and showed that TNF-alpha or IFN-gamma caused a 3.5- and greater than 12-fold increase respectively, in its promoter activity, when linked to a luciferase reporter gene and stably transfected into FRTL-5 cells. TSH or forskolin, in contrast, halved the activity of the full length chimera within 24 hours and significantly suppressed the TNF-alpha and IFN-gamma-induced increase (>50%; p < 0.02). Using 5'-deletion mutants, we located the element important for the TNF-alpha effect between -431 and -175 bp; we additionally show that deletion of a NF-kappaB core element within this region, TTGGAAATTC (-240 to -230 bp), causes the loss of TNF-alpha inducibility. The effect of IFN-gamma could be localized between -175 bp and -97 bp from the start of translation. This region contains 2 regulatory elements known to be involved in IFN-gamma action in other eukaryotic cells, an IFN-gamma activated site (GAS), -138 to -128 bp, and Spl site, -112 to -108 bp. Deletion of the 10 bp GAS sequence resulted in the complete loss of IFN-gamma induction of pCAM-175 promoter activity. TSH and forskolin action was also mapped between -175 bp and -97 bp from the start of translation. The mutant construct, pCAM-175delGAS mutl, which has no GAS sequence, exhibited no TSH-mediated suppression of promoter activity. We thus show that TSH/cAMP can downregulate ICAM-1 gene expression and inhibit the activity of cytokines (TNF-alpha and IFN-gamma) to increase ICAM-1 gene expression in FRTL-5 thyroid cells. We also localized elements on the 5'-flanking region of ICAM-1 important for these actions. We propose that this TSH/cyclic adenosine monophosphate (cAMP) action is a component of the mechanism to preserve self-tolerance of the thyroid during hormone-induced growth and function of the gland, and it may attenuate cytokine action during inflammatory reactions.

Clinical validity of intercellular adhesion molecule-1 (ICAM-1) and TSH receptor antibodies in sera from patients with Graves' disease

We compared the concentrations of soluble intercellular adhesion molecule-1 (sICAM-1) and the activities of thyroid-stimulating antibodies (TSAb) and thyrotropin-receptor antibodies (TBIAb) as measured with a commercial kit (TRAK). Sera were obtained from patients with Graves' disease (GD) before, during and after therapy with carbimazole (1-methyl-2-thio-3-carbethoxyimidazole). In all the situations, TSAb method was more sensitive than TBIAb. These two parameters dropped during therapy and were not correlated at any stage of measurement. sICAM-1 levels increased in 56.4% of patients before treatment, remained elevated at the beginning of treatment and decreased after twelve months of therapy. TSAb levels were significantly different between patients in relapse (78%) and those in remission (18%) (Z = -2.250, P = 0.025), with a relapse rate depending on the TSAb positivity (chi 2 = 7.103, P = 0.0077). Positive sICAM-1 values were found in 3 of the 9 (33.3%) patients who relapsed after discontinuing the drug but were negative in all the patients remaining in remission with a significant difference (Z = -1.982, P = 0.0475). The relapse rate was also dependent on positive sICAM-1 values (chi 2 = 3.958, P = 0.0466). No correlation was found between sICAM-1 levels and anti-TSH receptor antibodies TSAb or TBIAb. We conclude that the TBIAb technique is too insensitive to explore GD. TSAb and sICAM-1 assays in patients with GD are good markers of immune process after treatment withdrawal. Because of its rapid implementation, the sICAM-1 assay may advantageously replace TSAb measurement for forming a prognosis of GD.

Increased expression of CD44 variants in differentiated thyroid cancers

Expression of CD44 variants in thyroid tumors was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) with a fluorescent image analyzer. Increased expression of CD44 variants compared with normal thyroid tissues was observed in most thyroid follicular tumors, especially in follicular carcinomas, poorly differentiated papillary carcinomas and some follicular adenomas. However, variants were hardly detectable in an anaplastic carcinoma. Analysis with restriction enzymes revealed that the major PCR product, consisting of variant bands, was derived from CD44E. Therefore, the expression of CD44E may be associated with the proliferation of differentiated thyroid cells.

Adhesion molecules in autoimmune disease

Leukocyte activation, circulation, and localization to inflammatory sites are dependent on adherence to molecules on other cells or to extracellular matrix ligands. Adhesion molecule expression and interactions are probably involved in initiation and propagation of autoimmune diseases. Adhesion molecules pertinent to the development of autoimmunity are the subject of this review. Material in this review was generated by a manual and a computerized search of medical literature pertaining to adhesion molecules and specific autoimmune diseases. Topics covered include adhesion molecule classification, regulation of adhesion, and characterization of adhesion receptors in specific autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus, Sjögren's syndrome, autoimmune thyroid disease, multiple sclerosis, and diabetes mellitus. Adhesion molecules are classified into selectin, integrin, and immunoglobulin supergene family groups. Increased adhesion molecule expression and avidity changes occurring with cellular activation are the principal methods regulating leukocyte adhesion. Tumor necrosis factor-alpha (TNF alpha), interferon-gamma (IFN-gamma), and interleukin-1 (IL-1) stimulate adhesion receptor expression on lymphoid and nonlymphoid tissues. Although differences between specific autoimmune diseases exist, key interactions facilitating the development of autoimmune inflammation appear to include L-selectin/P-selectin/E-selectin, lymphocyte function-associated antigen-1 (LFA-1)/intercellular adhesion molecule-1 (ICAM-1), very late antigen-4 (VLA-4)/vascular cell adhesion molecule-1 (VCAM-1), and alpha 4B7/MadCAM or VCAM-1 adhesion. Administration of anti-adhesion molecule antibodies in experimental animal models of autoimmunity and in a preliminary trial with RA patients has been successful in preventing or reducing autoimmune disease severity. A vast array of adhesive interactions occurs between immunocompetent cells, endothelium, extracellular matrix, and target tissues during the evolution of an autoimmune disease. Further characterization of leukocyte migration patterns and adherence should clarify pathogenic processes in specific autoimmune diseases and identify potential therapeutic targets for their treatment.

Cytokines and thyroid function

Cytokines play a crucial role in autoimmune thyroid disease (ATD) through various mechanisms. They are produced in the thyroid by intrathyroidal inflammatory cells, in particular lymphocytes, as well as by the thyroid follicular cells (TFC) themselves and may thus act in a cascade to enhance the autoimmune process (Fig. 1). Cytokines upregulate the inflammatory reaction through stimulation of both T and B cells, resulting in antibody production and tissue injury. In addition, intrathyroidal cytokines induce immunological changes in TFC including enhancement of both major histocompatibility complex (MHC) class I and class II molecule expression, and upregulation of adhesion and complement regulatory molecule expression. Cytokines can also modulate both growth and function of TFC and have a role in extrathyroidal complications of ATD, most importantly thyroid-associated ophthalmopathy (TAO), where they induce fibroblast proliferation and enhance the production of glycosaminoglycans (GAG), resulting in proptosis and the other clinical features of the disease. In addition to these effects, exogenous administration of cytokines has been associated with impairment of thyroid function ranging from the appearance of autoantibodies alone to the development of frank thyroid dysfunction. Cytokines have also been implicated in subacute thyroiditis (SAT) and amiodarone-induced thyroid dysfunction, as well as in thyroid function abnormalities occurring in patients with non-thyroidal illnesses (NTI). Genetic variations in cytokine genes represent potential risk factors for ATD, and disease associations have been described for polymorphisms in IL-1ra and TNF beta genes. Recent experimental evidence suggests the possibility of novel cytokine-based therapeutic approaches for ATD and its complications, in particular TAO.

Intercellular adhesion molecule-1 (ICAM-1) in the sera of patients with Graves' disease: correlation with disease activity and treatment status

Intercellular adhesion molecule (ICAM-1), a ligand for lymphocyte function-associated antigen-1 (LFA-1), plays an important role in a variety of immune-mediated mechanisms such as lymphocyte attachment to cultured Graves' thyroid cells. We report the detection of a soluble form of the ICAM-1 molecule (sICAM-1) in sera from patients with Graves' disease (GD) and other thyroid disorders. The mean (+/- SD) sICAM-1 concentration in 28 euthyroid control subjects was 1931 +/- 681 pmol/L. The mean sICAM-1 concentration in 25 untreated hyperthyroid patients with GD was significantly elevated (3065 +/- 890 pmol/L), and decreased significantly (2489 +/- 845 pmol/L) after treatment with antithyroid drugs and/or 131I. Of 14 GD patients who had been in remission following administration of antithyroid drugs, 12 had recurrent disease. In 10 of the 12 patients in whom GD recurred, the sICAM-1 concentration (3807 +/- 796 pmol/L) increased significantly. The mean sICAM-1 concentration in patients with hypothyroidism due to chronic thyroiditis (n = 15:2895 +/- 569 pmol/L) was significantly elevated over that of control subjects, and not different from untreated hyperthyroid patients. The mean sICAM-1 concentration in patients with subacute thyroiditis (n = 13: 3036 +/- 441 pmol/L) was significantly elevated, while the mean sICAM-1 concentration in patients with nodular goiter (n = 10: 2318 +/- 490 pmol/L) was within the normal range. These results indicate that mean serum sICAM-1 concentration was significantly elevated in patients with untreated GD, and it decreased after treatment and increased at the time of recurrence. Therefore, the elevated serum concentration of sICAM-1 in patient with GD probably reflects ongoing immune processes.

Soluble endothelium-associated adhesion molecules in patients with Graves' disease

The targeting and recruitment of inflammatory cells to vascular endothelium in Graves' disease (GD) is mediated by intercellular adhesion molecule-1 (ICAM-1), endothelial leucocyte adhesion molecule-1 (ELAM-1), and vascular cell adhesion molecule-1 (VCAM-1). We have studied serum levels of soluble ICAM-1 (sICAM-1), soluble ELAM-1 (sELAM-1), and soluble VCAM-1 (sVCAM-1) in patients with GD (n = 21) and in patients with iodine-deficient goitre (IDG) (n = 23). The serum levels of sICAM-1 were markedly elevated in patients with GD before treatment with thiamazole (median 560 ng/ml versus 185 ng/ml in patients with IDG). In addition, elevated serum concentrations of sELAM-1 (median 85 ng/ml versus 33 ng/ml, respectively) and sVCAM-1 (median 42 ng/ml versus 15 ng/ml, respectively) were observed in patients with GD (P < 0.01 for all). The serum levels of sELAM-1 and sVCAM-1 dropped significantly after initiation of therapy and were within the normal range after 4, and 8 weeks of therapy, respectively. Serum levels of sICAM-1 were elevated even after 8 weeks of therapy. Serum levels of sVACM-1 and sICAM-1 correlated with the serum concentrations of anti-thyroid-stimulating hormone (TSH)-receptor antibodies (TSHR-R) (n = 21; r = 0.929 and r = 0.810, respectively) and anti-thyroid peroxidase antibodies (TPO-Ab) (n = 21; r = 0.673 and r = 0.750, respectively). However, no correlation between sELAM-1 and TPO-Ab, TSHR-R, and anti-thyroglobulin antibodies (Tg-Ab), respectively, could be found. In addition to thyroid hormones and autoantibodies, serum concentrations of sELAM-1 and sVCAM-1, but not sICAM-1, could be useful as clinical markers for disease activity.

The potential immunological role of the thyroid cell in autoimmune thyroid disease

Over the last decade it has become evident that thyroid follicular cells express a number of immunologically active molecules in autoimmune thyroid disease that may endow them with the capacity to interact with cells of the classical immune system. Expression of major histocompatibility complex class II molecules is induced by gamma-interferon, but there is no evidence yet that thyroid follicular cells can concurrently express the costimulatory signals necessary for class II expression to result in T cell stimulation: in this situation, class II expression may have a protective role, inducing T cell anergy. Thyroid follicular cells also express a variety of cell surface proteins (in particular CD59) that may protect the cells from complement attack. On the other hand, the expression of adhesion molecules and cytokines by thyrocytes would seem to be harmful, as these are likely to exacerbate autoimmune injury. Further study of the immunological role of thyroid follicular cells will shed new light on the pathogenesis of Graves' disease and autoimmune hypothyroidism, and may lead to novel therapeutic approaches to these disorders.