Increased expression of endothelin-1 and its mitogenic receptor ETA in human papillary thyroid carcinoma

The Endothelin-A Receptor Antagonist Zibotentan Induces Damage to the Nasal Olfactory Epithelium Possibly Mediated in Part through Type 2 Innate Lymphoid Cells

Zibotentan, an endothelin-A receptor antagonist, has been used in the treatment of various cardiovascular disorders and neoplasia. Castrated athymic nude mice receiving zibotentan for a preclinical xenograft efficacy study experienced weight loss, gastrointestinal bloat, and the presence of an audible respiratory click. Human side effects have been reported in the nasal cavity, so we hypothesized that the nasal cavity is a target for toxicity in mice receiving zibotentan. Lesions in the nasal cavity predominantly targeted olfactory epithelium in treated mice and were more pronounced in castrated animals. Minimal lesions were present in vehicle control animals, which suggested possible gavage-related reflux injury. The incidence, distribution, and morphology of lesions suggested direct exposure to the nasal mucosa and a possible systemic effect targeting the olfactory epithelium, driven by a type 2 immune response, with group 2 innate lymphoid cell involvement. Severe nasal lesions may have resulted in recurrent upper airway obstruction, leading to aerophagia and associated clinical morbidity. These data show the nasal cavity is a target of zibotentan when given by gavage in athymic nude mice, and such unanticipated and off-target effects could impact interpretation of research results and animal health in preclinical studies.

Polymorphisms of endothelin 1 (G5665T and T-1370G) and endothelin receptor type A (C+70G and G-231A) in Graves' disease

PURPOSE

Endothelin 1 (EDN1) is a strong angiogenic and mitogenic factor, playing a key role in hypervascularization, thyroid follicle cell hyperplasia, and lymphocyte infiltration in the thyroid gland of patients with Graves' disease (GD). EDN1 induces angiogenesis and mitogenesis via endothelin receptor type A (EDNRA). This study examined the possible association of EDN1 (G5665T and T-1370G) and EDNRA (C+70G and G-231A) single nucleotide polymorphisms (SNPs) with the occurrence of GD, and evaluates the relationship between genotypes and clinical/laboratory manifestations of GD.

MATERIALS AND METHODS

We analyzed genotype and allele distributions of EDN1 and EDNRA polymorphisms in 165 patients with GD and 181 healthy controls by real-time PCR combined with melting curve analysis.

RESULTS

No significant associations between GD and variant alleles of the studied polymorphisms were observed. However, the anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) levels in EDN1 G5665T GG genotype were higher than those in T allele carriers (GT+TT) (p=0.001 and p=0.026, respectively). In addition, anti-TPO levels in EDN1 T-1370G wild-type homozygous patients were found to be higher than in mutant gene carrying patients (GT+GG) (p=0.006). The presence of EDNRA+70G allele was associated with 3.37-fold increased risk for development of ophthalmopathy in GD patients (p=0.009).

CONCLUSION

Although there were no associations between EDN1 (G5665T and T-1370G) and EDNRA (C+70G and G-231A) SNPs and susceptibility to GD, EDN1 G5665T and T-1370G polymorphisms were related to alterations of autoantibody production and EDNRA C+70G polymorphism is related with increased risk for ophthalmopathy in GD patients.

Expression profile of endothelin 1 and its receptor endothelin receptor A in papillary thyroid carcinoma and their correlations with clinicopathologic characteristics

The endothelin axis is a group of signaling molecules and their receptors that have been implicated in vascularization of cancers, with their expression being observed to change in different cancer types. In this research, we examined the expression of endothelin 1 and endothelin receptor A at the protein and messenger RNA (mRNA) levels in 123 papillary thyroid carcinomas and 40 matched lymph nodes with metastatic papillary thyroid carcinomas. We found altered endothelin axis mRNA expression in several clinicopathologic parameters with increased endothelin 1 expression in thyroid papillary carcinoma showing stromal calcification, cancers in men, and primary cancers with lymph node metastases. Increased endothelin receptor A mRNA expression was noted in the larger cancers. There is a significant correlation between expression of endothelin receptor A and endothelin 1 in papillary thyroid carcinoma. Both endothelin receptor A and endothelin 1 mRNA expressions were significantly higher in metastatic carcinoma in the lymph node than in primary thyroid cancer. The metastatic carcinoma in the lymph node had increased expression compared with matched primary thyroid carcinoma. Expressions of endothelin 1 and endothelin receptor A were also documented as being high at the protein level. Our results indicate that in thyroid cancer, endothelin 1 and endothelin receptor A are associated with growth in advanced stages and lymph node metastases, likely through known angiogenic linkages. Targeting the endothelin axis may be useful in planning angiogenesis therapy for thyroid cancer.

A review of the profile of endothelin axis in cancer and its management

The endothelins and their associated receptors are important controllers of vascular growth, inflammation and vascular tone. In cancer, they have roles in the control of numerous factors in cancer development and progression, including angiogenesis, stromal reaction, epithelial mesenchymal transitions, apoptosis, invasion, metastases and drug resistance. Also, we consider current information on the role of this signalling system in cancer and examine the state of the current cell, animal and clinical trials utilizing endothelin targeted drugs for cancer management. Although targeting the endothelin axis in cell lines and xenografts show some promise in retarding cellular growth, results from limited clinical trials in prostatic cancer are less encouraging and did not offer significant survival benefit. The ability to target both cancer cells and vasculature via endothelin is an important consideration that necessitates the further refining of therapeutic strategies as we continue to explore the possibilities of the endothelin axis in cancer treatment.

Assessment of endothelin-A receptor expression in subcutaneous and orthotopic thyroid carcinoma xenografts in vivo employing optical imaging methods

Endothelin (ET) receptor dysregulation has been described in a number of pathophysiological processes, including cardiovascular disorders, renal failure, and cancer. The aim of this study was to evaluate the expression of the ET-A receptor (ET(A)R) in murine models of thyroid carcinoma using optical imaging methods. A recently developed near-infrared fluorescent tracer was first assessed in isolated artery preparations for its functional performance in comparison with known ET(A)R antagonists BQ123 and PD156707. Before evaluation of the tracer in vivo, different thyroid carcinoma cell lines were characterized with respect to their ET receptor expression by RT-PCR and autoradiography. In vivo, sc and orthotopic papillary thyroid tumor xenografts were clearly visualized by fluorescence reflectance imaging and fluorescence-mediated tomography up to 48 h after injection of the tracer. Binding specificity of the probe was demonstrated by predosing with PD156707 as a competing inhibitor. In conclusion, optical imaging with a fluorescent ET(A)R tracer allows the noninvasive imaging of tumor-associated ET(A)R expression in vivo. In the future, this technique may help surgeons to evaluate lesion dimensions in intraoperative settings (e.g. thyroidectomy).

Atrasentan (ABT-627) enhances perfusion and reduces hypoxia in a human tumor xenograft model

The endothelin-1 antagonist, Atrasentan (ABT-627) was used to modify perfusion in the human tumor xenograft model, HT29, growing in nude mice. Atrasentan produced a significant increase in perfusion, as measured in vivo by Gd-DTPA DCE-MRI. Changes in tumor hypoxia were assessed by comparing the binding of two hypoxia tracers, pimonidazole and EF5 given before and after Atrasentan administration. In vehicle-treated controls, the distribution of EF5 and pimonidazole was very similar. However, Atrasentan treatment was associated with decreased uptake of the second hypoxia tracer (EF5), relative to the first (pimonidazole). Although Atrasentan had no independent effect on the growth of HT29 tumors, Atrasentan combined with 20 Gy radiation led to a modest but significant increase in tumor growth delay compared to radiation alone.

Elevation of circulating big endothelin-1: an independent prognostic factor for tumor recurrence and survival in patients with esophageal squamous cell carcinoma

BACKGROUND

Endothelin(ET) axis plays a key role in many tumor progression and metastasis via various mechanisms such as angiogenesis, mediating extracellular matrix degradation and inhibition of apoptosis. However, there is limited information regarding the clinical significance of plasma big ET-1 levels in esophageal cancer patients. Circulating plasma big ET-1 levels were measured in patients with esophageal squamous cell carcinoma(ESCC) to evaluate the value of ET-1 as a biomarker for predicting tumor recurrence and patients survival.

METHODS

Preoperative plasma big ET-1 concentrations were measured by an enzyme linked immunosorbent assay(ELISA) in 108 ESCC patients before surgery, and then again at 1,2,3,10 and 30 days after curative radical resection for ESCC. The association between preoperative plasma big ET-1 levels and clinicopathological features, tumor recurrence and patient survival, and their changes following surgery were evaluated.

RESULTS

The preoperative plasma big ET-1 levels in ESCC patients were significantly higher than those in controls. And there was a significant association between plasma big ET-1 levels and disease stage, as well as invasion depth of the tumor and lymph node status. Furthermore, plasma big ET-1 levels decreased significantly after radical resection of the primary tumor and patients with postoperative recurrence had significantly higher plasma big ET-1 levels than that of patients without recurrence. Finally, the survival rate of patients with higher plasma big ET-1 concentrations (>4.3 pg/ml) was significantly lower than that of patients with lower level (< or = 4.3 pg/ml). Multivariate regression analysis showed that plasma big ET-1 level is an independent prognostic factor for survival in patients with ESCC.

CONCLUSION

Plasma big ET-1 level in ESCC patients may reflect malignancy and predict tumor recurrence and patient survival. Therefore, the preoperative plasma big ET-1 levels may be a clinically useful biomarker for choice of multimodality therapy in ESCC patients.

Role of the endothelin axis in the proliferation of human thyroid cancer cells

OBJECTIVE

Endothelin-1 (ET-1) may play a role in carcinogenesis. ET-1 axis is overexpressed in thyroid carcinoma. We investigated the expression and the production of ET-1 by thyroid cancer cells as well as the effect of ET-1 receptor antagonism on cell proliferation.

DESIGN

Human papillary and follicular thyroid carcinoma cell lines were cultured.

MEASUREMENTS

(i) Prepro-ET-1, ET-1 receptors (ETA R and ETB R) and ET-1 converting enzyme (ECE) by reverse transcriptase polymerase chain reaction (RT-PCR); (ii) the presence of ETA R by western blot; (iii) ET-1 concentrations in medium by an enzyme immunometric assay; (iiii) the proliferation of cells by BrdU and tritiated thymidine incorporation.

RESULTS

RT-PCR detected the presence of mRNA for prepro-ET-1, ETA R and ECE in papillary and follicular carcinoma cells. ETB R was only expressed by follicular cells. ETA R was also detected in both cell types by western blot. Measurements of ET-1 concentrations demonstrated a secretion of active ET-1 by the cells. ETA R antagonism with atrasentan reduced cell proliferation by 16% in papillary carcinoma cells (P < 0.05) and by 51% in follicular carcinoma cells (P < 0.001).

CONCLUSIONS

Papillary and follicular carcinoma cells express all components of the ET-1 axis. ETA R antagonism exerts antiproliferative effects, which opens up new therapeutic perspectives in thyroid carcinoma.

Effect of endothelin-1 in esophageal squamous cell carcinoma invasion and its correlation with cathepsin B

AIM: To investigate the effect of endothelin-1 in the invasion of esophageal cancer and determine whether cathepsin B plays a role in the course.

METHODS: Western blotting was employed to detect the expression of ET-1 protein in 75 samples of esophageal squamous cell cancer and matched normal esophageal mucosa. Bosentan, a dual ET (A/B)-receptor antagonist, was used to inhibit the binding of endothelin-1 and its receptors and cut down its biological role. In vitro matrigel invasion assays were made to show the invasive ability of esophageal cancer cells with and without bosentan. Subsequently, we evaluated cathepsin B activity and expression in EC9706 cell with and without bosentan.

RESULTS: We found 74.7% (56/75) tumors had an overexpression of ET-1 protein by Western blotting. Bosentan significantly inhibited matrigel invasion of cancer cells in vitro. EC9706 cells have a positive expression of cathepsin B protein, and bosentan can down-regulate its expression and activity.

CONCLUSION: Endothelin-1 may enhance the invasive ability of human esophageal cancer cells, and its role is correlated with cathepsin B.

ZD4054, a specific antagonist of the endothelin A receptor, inhibits tumor growth and enhances paclitaxel activity in human ovarian carcinoma in vitro and in vivo

The autocrine endothelin (ET)-1/endothelin A receptor (ET(A)R) pathway is an important regulator of several processes involved in ovarian cancer progression, and its overexpression is associated with aggressive disease. These features have led to the proposal of the ET(A)R receptor as a potential target for improving ovarian cancer treatment. In this study, we evaluated in vitro and in vivo the effects of ZD4054, an orally active antagonist that specifically binds ET(A)R, as monotherapy, and in combination with paclitaxel. In the human ovarian cancer ET(A)R-positive cell lines HEY, OVCA 433, SKOV-3, and A-2780, ZD4054 effectively inhibited the basal and ET-1-induced cell proliferation, associated with the inhibition of AKT and p42/44MAPK phosphorylation, and with increased apoptosis, through the inhibition of bcl-2 and activation of caspase-3 and poly(ADP-ribose) polymerase proteins. ZD4054 treatment also resulted in a reduction of ET(A)R-driven angiogenesis and invasive mediators, such as vascular endothelial growth factor, cyclooxygenase-1/2, and matrix metalloproteinase (MMP). The combination of ZD4054 and paclitaxel led to the potentiation of all these effects, indicating that ZD4054, by blocking the ET(A)R-dependent proliferative, invasive, and antiapoptotic signals, can enhance sensitivity to paclitaxel. In HEY ovarian cancer xenografts, ZD4054 significantly inhibited tumor growth to the same degree as paclitaxel. Furthermore, ZD4054-dependent tumor growth inhibition was associated with a reduction in proliferation index, microvessel density, and MMP-2 expression. Interestingly, the combination of ZD4054 and paclitaxel produced additive antitumor effects, with 40% of mice remaining tumor-free, supporting a rationale for the clinical use of ZD4054 as monotherapy or in combination with cytotoxic drugs.

Therapeutic targeting of the endothelin a receptor in human nasopharyngeal carcinoma

The endothelin A receptor (ET(A)R) autocrine pathway is overexpressed in many malignancies, including nasopharyngeal carcinoma (NPC). In this tumor, ET(A)R expression is an independent determinant of survival and a robust independent predictor of distant metastasis. To evaluate whether ET(A)R represents a new target in NPC treatment, we tested the therapeutic role of ET(A)R in NPC. Cell proliferation was inhibited by the ET(A)R-selective antagonist ABT-627 in two ET(A)R-positive NPC cells in a dose-dependent manner. Proliferation of ET(A)R-negative NPC cells was not decreased. ET(A)R blockade also resulted in sensitization to cisplatin and 5-fluorouracil-induced apoptosis. In nude mice, ABT-627 inhibited the growth of NPC cell xenografts. Combined treatment of ABT-627 with the cytotoxic drug cisplatin or 5-fluorouracil produced additive antitumor effects. The antitumor activity of ABT-627 was demonstrated finally on an experimental lung metastasis by a reduction in the number of tumors. These results support the rationale of combining ABT-627 with current standard chemotherapy to further improve the therapeutic ratio in the treatment of NPC.

Interrelated overexpression of endothelial and inducible nitric oxide synthases, endothelin-1 and angiogenic factors in human papillary thyroid carcinoma

OBJECTIVE

Nitric oxide (NO) and endothelin-1 (ET-1) are involved in carcinogenesis. Overexpression of the ET-1 axis has been demonstrated in papillary thyroid carcinoma (PTC). This study investigated the expression of NO synthases (NOS) and their relationship with expression of ET-1 and angiogenic markers in PTC.

DESIGN AND PATIENTS

Expression of NOS, angiogenic markers [vascular endothelial growth factor (VEGF), angiopoietin-1 and angiopoietin-2] and their receptors was studied in surgical thyroid samples obtained from 22 patients aged 15-68 years. Three groups were constituted: normal thyroid (n = 5), Hashimoto's thyroiditis (n = 9) and PTC (n = 8).

RESULTS

Immunohistochemistry disclosed NOS2 and NOS3 immunoreactivity in PTC cells, the percentage of positive cells being greater than normal (P < 0.02). Real-time quantitative polymerase chain reaction (RTQ-PCR) showed that NOS2 and NOS3 mRNA levels were, respectively, increased (P < 0.02) by 2.6 +/- 0.6 and 4.2 +/- 1.1 times in PTC. RTQ-PCR demonstrated that VEGF, its receptors VEGFR-1 and VEGFR-2, and angiopoietin-2 and its receptor (Tie2) were also overexpressed (P < 0.05) in PTC. Correlations were found between ET-1 expression and that of NOS2, angiopoietin-1 and -2 (P < 0.05). NOS2 mRNA levels also correlated with those of NOS3 and angiopoietin-2 (P < 0.05). In thyroiditis, NOS2 immunoreactivity was observed in inflammatory cells whereas NOS2 mRNA levels were 12.1 +/- 1.6 times higher than normal (P < 0.005).

CONCLUSIONS

This study revealed an activation of the NO pathway in thyroid carcinoma, which is interrelated to the ET-1 axis, both systems being overexpressed in concert with angiogenic factors. This global system might play a role in carcinogenesis and constitutes a potential target for anticancer therapy.

Chromosomal aberrations in cell lines derived from thyroid tumors spontaneously developed in TRbetaPV/PV mice

The etiology and genetic alterations of follicular thyroid carcinoma are not well understood. By targeting a mutation (PV) into the thyroid hormone receptor beta gene (TRbetaPV mouse), we created a knock-in mutant TRbeta(PV/PV) mouse that spontaneously develop follicular thyroid carcinoma with progression to metastasis similar to human follicular thyroid carcinoma. This mouse model provides a valuable tool to ascertain the nature and the extent of genomic rearrangements that occur during carcinogenesis of the thyroid. Spectral karyotyping analysis (SKY) of seven cell lines derived from thyroid tumors developed in TRbeta(PV/PV) mice showed that all of them had abnormal karyotypes, with chromosome number ranging from near-diploid (39-42 chromosomes) to hypotetraploid (63-79 chromosomes). These seven cell lines also exhibited a variety of structural chromosomal aberrations, including common recurrent translocations and deletions. This SKY analysis shows that the development and progression of follicular thyroid carcinoma in knock-in TRbeta(PV/PV) mutant mice comprise recurrent structural and numerical genomic changes, some of which mimic those described in human thyroid cancer.

Endothelin-1 Is a Critical Mediator of Myogenic Tone in Tumor Arterioles

Although derived from the host tissue, the tumor vasculature is under the influence of the tumor microenvironment and needs to adapt to the resistance to blood flow inherent to the dynamics of tumor growth. Such vascular remodeling can offer selective targets to pharmacologically modulate tumor perfusion and thereby improve the efficacy of conventional anticancer treatments. Radiotherapy and chemotherapy can, indeed, take advantage of a better tumor oxygenation and drug delivery, respectively, both partly dependent on the tumor blood supply. Here, we showed that isolated tumor arterioles mounted in a pressure myograph have the ability, contrary to size-matched healthy arterioles, to contract in response to a transluminal pressure increase. This myogenic tone was exquisitely dependent on the endothelin-1 pathway because it was completely abolished by the selective endothelin receptor A (ETA) antagonist BQ123. This selectivity was additionally supported by the large increase in endothelin-1 abundance in tumors and the higher density of the ETA receptors in tumor vessels. We also documented by using laser Doppler microprobes and imaging that administration of the ETA antagonist led to a significant increase in tumor blood flow, whereas the perfusion in control healthy tissue was not altered. Finally, we provided evidence that acute administration of the ETA antagonist could significantly stimulate tumor oxygenation, as determined by electron paramagnetic resonance oximetry, and increase the efficacy of low-dose, clinically relevant fractionated radiotherapy. Thus, blocking the tumor-selective increase in the vascular endothelin-1/ETA pathway led us to unravel an important reserve of vasorelaxation that can be exploited to selectively increase tumor response to radiotherapy.