Synthesis and secretion of transforming growth factor-beta1 by human desmoid fibroblast cell line and its modulation by toremifene

Activated Signaling Pathways and Targeted Therapies in Desmoid-Type Fibromatosis: A Literature Review

Desmoid-type fibromatosis (DTF) is a rare, soft tissue tumor of mesenchymal origin which is characterized by local infiltrative growth behavior. Besides “wait and see,” surgery and radiotherapy, several systemic treatments are available for symptomatic patients. Recently, targeted therapies are being explored in DTF. Unfortunately, effective treatment is still hampered by the limited knowledge of the molecular mechanisms that prompt DTF tumorigenesis. Many studies focus on Wnt/β-catenin signaling, since the vast majority of DTF tumors harbor a mutation in the CTNNB1 gene or the APC gene. The established role of the Wnt/β-catenin pathway in DTF forms an attractive therapeutic target, however, drugs targeting this pathway are still in an experimental stage and not yet available in the clinic. Only few studies address other signaling pathways which can drive uncontrolled growth in DTF such as: JAK/STAT, Notch, PI3 kinase/AKT, mTOR, Hedgehog, and the estrogen growth regulatory pathways. Evidence for involvement of these pathways in DTF tumorigenesis is limited and predominantly based on the expression levels of key pathway genes, or on observed clinical responses after targeted treatment. No clear driver role for these pathways in DTF has been identified, and a rationale for clinical studies is often lacking. In this review, we highlight common signaling pathways active in DTF and provide an up-to-date overview of their therapeutic potential.

The Wnt/β-catenin pathway in human fibrotic-like diseases and its eligibility as a therapeutic target

The canonical Wnt signaling pathway is involved in a variety of biological processes like cell proliferation, cell polarity, and cell fate determination. This pathway has been extensively investigated as its deregulation is linked to different diseases, including various types of cancer, skeletal defects, birth defect disorders (including neural tube defects), metabolic diseases, neurodegenerative disorders and several fibrotic diseases like desmoid tumors. In the "on state", beta-catenin, the key effector of Wnt signaling, enters the nucleus where it binds to the members of the TCF-LEF family of transcription factors and exerts its effect on gene transcription. Disease development can be caused by direct or indirect alterations of the Wnt/β-catenin signaling.

In the first case germline or somatic mutations of the Wnt components are associated to several diseases such as the familial adenomatous polyposis (FAP) - caused by germline mutations of the tumor suppressor adenomatous polyposis coli gene (APC) - and the desmoid-like fibromatosis, a sporadic tumor associated with somatic mutations of the β-catenin gene (CTNNB1).

In the second case, epigenetic modifications and microenvironmental factors have been demonstrated to play a key role in Wnt pathway activation. The natural autocrine Wnt signaling acts through agonists and antagonists competing for the Wnt receptors. Anomalies in this regulation, whichever is their etiology, are an important part in the pathogenesis of Wnt pathway linked diseases. An example is promoter hypermethylation of Wnt antagonists, such as SFRPs, that causes gene silencing preventing their function and consequently leading to the activation of the Wnt pathway. Microenvironmental factors, such as the extracellular matrix, growth factors and inflammatory mediators, represent another type of indirect mechanism that influence Wnt pathway activation. A favorable microenvironment can lead to aberrant fibroblasts activation and accumulation of ECM proteins with subsequent tissue fibrosis that can evolve in fibrotic disease or tumor.

Since the development and progression of several diseases is the outcome of the Wnt pathway cross-talk with other signaling pathways and inflammatory factors, it is important to consider not only direct inhibitors of the Wnt signaling pathway but also inhibitors of microenvironmental factors as promising therapeutic approaches for several tumors of fibrotic origin.

The Wnt/β-catenin pathway in human fibrotic-like diseases and its eligibility as a therapeutic target

The canonical Wnt signaling pathway is involved in a variety of biological processes like cell proliferation, cell polarity, and cell fate determination. This pathway has been extensively investigated as its deregulation is linked to different diseases, including various types of cancer, skeletal defects, birth defect disorders (including neural tube defects), metabolic diseases, neurodegenerative disorders and several fibrotic diseases like desmoid tumors. In the "on state", beta-catenin, the key effector of Wnt signaling, enters the nucleus where it binds to the members of the TCF-LEF family of transcription factors and exerts its effect on gene transcription. Disease development can be caused by direct or indirect alterations of the Wnt/β-catenin signaling. In the first case germline or somatic mutations of the Wnt components are associated to several diseases such as the familial adenomatous polyposis (FAP) - caused by germline mutations of the tumor suppressor adenomatous polyposis coli gene (APC) - and the desmoid-like fibromatosis, a sporadic tumor associated with somatic mutations of the β-catenin gene (CTNNB1). In the second case, epigenetic modifications and microenvironmental factors have been demonstrated to play a key role in Wnt pathway activation. The natural autocrine Wnt signaling acts through agonists and antagonists competing for the Wnt receptors. Anomalies in this regulation, whichever is their etiology, are an important part in the pathogenesis of Wnt pathway linked diseases. An example is promoter hypermethylation of Wnt antagonists, such as SFRPs, that causes gene silencing preventing their function and consequently leading to the activation of the Wnt pathway. Microenvironmental factors, such as the extracellular matrix, growth factors and inflammatory mediators, represent another type of indirect mechanism that influence Wnt pathway activation. A favorable microenvironment can lead to aberrant fibroblasts activation and accumulation of ECM proteins with subsequent tissue fibrosis that can evolve in fibrotic disease or tumor. Since the development and progression of several diseases is the outcome of the Wnt pathway cross-talk with other signaling pathways and inflammatory factors, it is important to consider not only direct inhibitors of the Wnt signaling pathway but also inhibitors of microenvironmental factors as promising therapeutic approaches for several tumors of fibrotic origin.

Signal transduction pathway analysis in desmoid-type fibromatosis: transforming growth factor-β, COX2 and sex steroid receptors

Despite reports of sex steroid receptor and COX2 expression in desmoid-type fibromatosis, responses to single agent therapy with anti-estrogens and non-steroidal anti-inflammatory drugs are unpredictable. Perhaps combination pharmacotherapy might be more effective in desmoid tumors that co-express these targets. Clearly, further understanding of the signaling pathways deregulated in desmoid tumors is essential for the development of targeted molecular therapy. Transforming growth factor-β (TGFβ) and bone morphogenetic proteins (BMP) are important regulators of fibroblast proliferation and matrix deposition, but little is known about the TGFβ superfamily in fibromatosis. A tissue microarray representing 27 desmoid tumors was constructed; 14 samples of healing scar and six samples of normal fibrous tissue were included for comparison. Expression of selected receptors and activated downstream transcription factors of TGFβ family signaling pathways, β-catenin, sex steroid hormone receptors and COX2 were assessed using immunohistochemistry; patterns of co-expression were explored via correlational statistical analyses. In addition to β-catenin, immunoreactivity for phosphorylated SMAD2/3 (indicative of active TGFβ signaling) and COX2 was significantly increased in desmoid tumors compared with healing scar and quiescent fibrous tissue. Low levels of phosphorylated SMAD1/5/8 were detected in only a minority of cases. Transforming growth factor-β receptor type 1 and androgen receptor were expressed in both desmoid tumors and scar, but not in fibrous tissue. Estrogen receptor-β was present in all cases studied. Transforming growth factor-β signaling appears to be activated in desmoid-type fibromatosis and phosphorylated SMAD2/3 and COX2 immunoreactivity might be of diagnostic utility in these tumors. Given the frequency of androgen receptor, estrogen receptor-β and COX2 co-expression in desmoid tumors, further assessment of the efficacy of combination pharmacotherapy using hormonal agonists/antagonists together with COX2 inhibitors should be considered.

Anti-oestrogen therapy in the treatment of desmoid tumours: a systematic review

AIM

The treatment of desmoid tumours (DTs) is controversial. Anti-oestrogen therapy has frequently been used, but clear information of its efficacy is lacking. In this systematic review we have undertaken a comprehensive analysis to assess the effectiveness of anti-oestrogen therapy in terms of ability to induce partial or complete regression of DTs.

METHOD

A systematic review of articles published in English between January 1983 and December 2009 was carried out according to the RECIST criteria. A literature search was performed on electronic databases including: United States National Library of Medicine (MEDLINE-PubMed), Excerpta Medica (EMBASE), Cochrane Library and Google search engine. Two-hundred articles dealing with DTs were identified but only fourty-one were were selected as appropriate for the study. The chi-square test was used for statistical analysis.

RESULTS

Data on 168 DTs treated with anti-oestrogen agents, alone or in combination with nonsteroidal anti-inflammatory drugs, were identified with an overall response rate of 51%. There was no difference in response according to the type of DTs or between different anti-oestrogen therapies. Combination with anti-inflammatory drugs did not improve the outcome. Toremifene was sometimes effective in cases resistant to tamoxifen. Response did not seem to be related to oestrogen receptor status.

CONCLUSIONS

Despite potential inaccuracies in the methodology, the results of the review indicate that anti-oestrogen therapy produces some effect in about one half of patients with DTs. Its indication compared with other treatments is discussed.

Successful treatment of desmoid tumor of the chest wall with tranilast: a case report

INTRODUCTION

Desmoid tumor is characterized by infiltrative growth and local recurrence often occurs after surgery. To reduce the local recurrence rate, adjuvant therapy, such as radiotherapy and pharmacotherapy with cytotoxic agents, anti-estrogen agents and non-steroidal anti-inflammatory drugs, is often applied. In addition, these non-surgical treatments are also performed in patients with unresectable desmoid tumors. We successfully treated a patient with a desmoid tumor with tranilast; an anti-allergic agent.

CASE PRESENTATION

A 48-year-old Japanese man with a slow-growing desmoid tumor on his chest wall was treated with an oral administration of tranilast (300 mg per day, three times a day). Two years and two months after the commencement of his therapy, the tumor became impalpable. At this time, the oral administration of tranilast was discontinued. Two years after discontinuation of the treatment, a physical examination showed no recurrence of the tumor and he continued in a state of remission. We were successfully able to reduce the size of the tumor and thereafter maintain the reduced size.

CONCLUSION

Tranilast was clinically effective in our case, and is probably comparable to cytotoxic agents or anti-estrogen agents. Because tranilast has substantially fewer adverse effects than cytotoxic agents, it could be a very useful therapeutic agent for desmoid tumor.

Toremifene decreases type I, type II and increases type III receptors in desmoid and fibroma and inhibits TGFbeta1 binding in desmoid fibroblasts

Tissue infiltration is different in desmoid and fibroma tumours. Both produce high levels of transforming growth factor beta1 (TGFbeta1), which is related to extracellular matrix (ECM) accumulation which in turn regulates cell function and cell migration. Interactions between collagen, proteoglycans and cell surface fibronectin are involved in the assembly and functions of the ECM. As toremifene inhibits collagen and TGFbeta1 synthesis, we tested it in normal, desmoid and fibroma fibroblasts. We will report the changes in glycosaminoglycan (GAG) and collagen synthesis, TGFbeta1 activity, fibronectin mRNA expression and TGFbeta1 receptors after toremifene treatment in normal, fibroma and desmoid fibroblasts. We evaluated GAG and collagen synthesis with 3H-glucosamine and 3H-proline incorporation, TGFbeta1 activity with the ELISA method, TGFbeta1 receptor affinity with 125I-TGFbeta1 binding and total RNA with Northern blot analysis. GAG and collagen synthesis, TGFbeta1 activity and fibronectin levels were higher in fibroma and desmoid than normal fibroblasts. The increase was greater in desmoid than fibroma tumour cells. Toremifene treatment reduced GAG and collagen synthesis, TGFbeta1 activity and fibronectin levels in all cell cultures. The percentage reduction in GAG was similar in all cultures; the reduction in collagen synthesis and TGFbeta1 activity was the highest in desmoid fibroblasts. TGFbeta1 receptors were higher in fibroma and desmoid cells than controls. Toremifene reduced TGFbeta1 receptors only in desmoid fibroblasts, with no effect on the changes in type I, II, and III receptors. Our data show that toremifene modifies the ECM components that regulate cytokine activity and cell migration. The reduction in receptor number only in desmoid cells suggests that toremifene may reduce TGFbeta1's affinity for its receptors. Synthesis of a substance regulating protein kinase activity, which is directly involved in the link between TGFbeta1 and its receptors, cannot be excluded.

Desmoid and fibroma tumors differently respond to TGFβ1 stimulus and ECM macromolecule accumulation

Desmoid and fibroma tumours are characterized by cell proliferation, glycosaminoglycan and collagen fibre accumulation, high levels of transforming growth factor beta(1) (TGFbeta(1)) and different patterns of tissue infiltration. TGFbeta(1) is related to extracellular matrix (ECM) composition which, in turn, regulates cell functions and cell migration. In this study we report changes in cell proliferation, glycosaminoglycan (GAG) and collagen synthesis, TGFbeta(1) mRNA expression and fibronectin levels in normal, desmoid and fibroma fibroblast cultures before and after TGFbeta(1) stimulation. Our data showed cell proliferation, GAG and collagen synthesis, transforming growth factor beta(1) mRNA expression and fibronectin levels were significantly higher in desmoid than in fibroma cultures. TGFbeta(1) treatment had no effect on cell proliferation, but increased TGFbeta(1) mRNA expression, GAG, fibronectin and collagen synthesis in desmoid and fibroma fibroblasts. Its effects were more marked in desmoid cells. Fibronectin favours cell migration, while changes in GAG composition alter cell behaviour and ECM organization. In conclusion our data suggest that the different patterns of infiltration in desmoid and fibroma tumours are due to changes in ECM components and cell-ECM interactions which can be ascribed to altered TGFbeta(1) mRNA expression and TGFbeta(1) activity.

A comparison of methods for the analysis of low abundance proteins in desmoid tumor cells

The desmoids are a group of rare clinically diverse, deep-seated fibrous neoplasms. The exact etiology is unknown, but several factors are considered to be positively correlated with their development and growth, i.e., genetic and hormonal factors and trauma. These tumors may be sporadic or associated with a genetic disease such as familial adenomatous polyposis (FAP). Devoid of metastatic potential, they tend to form large, infiltrative masses which, if not completely excised, recur repeatedly. Although surgery is widely accepted as the first-line treatment for extra-abdominal and abdominal wall desmoids, a proportion of cases are successfully palliated with either estrogen antagonists (tamoxifen, toremifene, and raloxifene) or nonsteroidal anti-inflammatory drugs. We describe and compare four methods for evaluating the expression of estrogen receptors alpha/beta and COX-1 and COX-2 in desmoid tumor-derived cells and tissues: immunocytochemistry, immunohistochemistry, RT-PCR, and two-color Western blot detection with the Odyssey infrared imaging system. Through this comparative analysis, Western blot with Odyssey was recognized as the best method to analyze the expression particularly of low expressed proteins in desmoid-derived cells. The use of a specific and reliable assessment method becomes fundamental in the evaluation of the presence and modulation of proteins which are important but weakly expressed in these rare tumors.

Estrogen receptor-β expression in extraabdominal fibromatoses

BACKGROUND

Early experiments using ligand-binding assays demonstrated the presence of estrogen receptor (ER) in fibromatoses. These findings were not confirmed by later studies using immunohistochemical analysis.

METHODS

To verify the expression of ERs in fibromatosis as well as to clarify the inconsistency between radioligand and early immunohistochemical studies, the authors examined a series of 40 extraabdominal fibromatoses using antibodies raised against ERbeta.

RESULTS

All 40 cases of extraabdominal fibromatosis were at least focally positive for ERbeta. Thirty-three of 40 (83%) displayed 3+ (>50%) expression, 5 of 40 (12%) were 2+ (11-50%), and 2 of 40 (5%) cases showed 1+ (<10%) expression. All cases were negative for ERalpha.

CONCLUSIONS

Although extraabdominal fibromatosis does not express ERalpha, there appears to be nearly uniform expression of ERbeta. This finding clarifies discrepancies in the literature regarding estrogen expression in fibromatosis, and provides a biological mechanism for the action of antiestrogenic compounds in the treatment of fibromatosis. Estrogen antagonists may have a role in the treatment of refractory or recurrent extraabdominal fibromatoses.

A Highly Vascular Intracranial Solitary Fibrous Tumor Treated with Radiotherapy and Toremifene: Case Report

OBJECTIVE AND IMPORTANCE:

A case of an unusual intracranial solitary fibrous tumor with features of high vascularity and resultant difficulty at resection is presented. The use of surgery, radiotherapy, and toremifene has been successful with no recurrence after 18 months.

CLINICAL PRESENTATION:

A 33-year-old male patient presented with a 1-year history of loss of vision on the left side and a 3-month history of headache and lethargy. Magnetic resonance imaging showed a lobulated mass (7.6 × 4.5 cm) in the left temporal fossa and left parasellar, sellar, and suprasellar regions, with a “dural tail” more typical of meningioma. Vascular supply was from both the internal carotid arteries and the left middle meningeal artery, precluding embolization.

INTERVENTION:

At the time of the craniotomy, a highly vascular tumor was found. Intraoperative hemorrhage limited resection to 20% of the tumor. The histological diagnosis was of a solitary fibrous tumor with an unusually angiomatoid architecture. After the operation, radiotherapy and toremifene were administered. A dramatic reduction in the size of the tumor was seen with no recurrence to date.

CONCLUSION:

The use of surgery, radiotherapy, and toremifene in treatment of a vascular intracranial solitary fibrous tumor has been successful and warrants further research.

Human desmoid fibroblasts: matrix metalloproteinases, their inhibitors and modulation by Toremifene

Background

Desmoid tumour is a benign, non metastasising neoplasm characterised by an elevated deposition of organic macromolecules in the extracellular matrix (ECM). The matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases involved in the degradation of ECM macromolecules. The MMPs and their natural inhibitors (TIMPs) have been implicated in tumour growth, invasion and metastasis. In this study we provide evidence that the in vitro cultured cell line from desmoid tumour accumulates more collagen fibres in the ECM than healthy fibroblasts.

Methods

We investigated collagen accumulation by ³H-thymidine incorporation, MMP expression by substrate gel zymography and TIMP expression by Western blot analysis.

Results

Desmoid fibroblasts showed a reduction in MMP activity and an increase of type I and III collagen and TIMPs compared to normal fibroblasts.

Conclusion

The increase in collagen in desmoid fibroblasts was due to inhibited collagen degradation (reduction of MMP activity) rather than to increased collagen synthesis. Adding toremifene, an anti-estrogen triphenylethylene derivate, to desmoid fibroblasts reduced collagen accumulation by decreasing mRNA expression and increasing collagen degradation.

Effects of transforming growth factor-beta1 and tumour necrosis factor-alpha on cultured fibroblasts from skin fibroma as modulated by toremifene

To determine how toremifene, an anti-oestrogen triphenylethylene derivate, reduces tumour mass, we investigated its modulation of TGF-beta1 and TNF-alpha in fibroma fibroblasts. Normal and fibroma fibroblasts, isolated from patients affected by Gardner's syndrome without or with fibroma manifestation, were cultured in vitro. Secretion of GAG, collagen and TGF-beta1 was increased in fibroma fibroblasts compared to healthy cells. The increase in TGF-beta1 secretion into the medium was associated with a parallel increase in TGF-beta1 gene expression and receptor number. Receptor cross-linking studies using radiolabelled TGF-beta1 revealed more receptors, particularly types I and II, in fibroma fibroblasts than in normal cells. Normal and fibroma fibroblasts did not synthesise TNF-alpha, but they had TNF-alpha membrane receptors, as shown by TNF-alpha assay. TNF-alpha secreted by human monocytes, which may be present in the peritumoral area, increased cell proliferation and GAG accumulation and was, in turn, enhanced by TGF-beta1 treatment. Both growth factors increased angiogenesis, as shown by the CAM assay. Toremifene reduced TGF-beta1 secretion by fibroma fibroblasts and TNF-alpha secretion by monocytes, thus downregulating cell proliferation, ECM macromolecule accumulation and angiogenic progression. We hypothesise that increased TGF-beta1 gene expression and TGF-beta1 secretion in fibroma fibroblasts as well as the subsequent rise in TNF-alpha production by monocytes may facilitate fibroma growth and that toremifene inhibits autocrine and paracrine growth factor production.