Transforming growth factor-beta and breast cancer: Cell cycle arrest by transforming growth factor-β and its disruption in cancer

Altered responsiveness to extracellular signals and cell cycle dysregulation are hallmarks of cancer. The cell cycle is governed by cyclin-dependent kinases (cdks) that integrate mitogenic and growth inhibitory signals. Transforming growth factor (TGF)-β mediates G₁ cell cycle arrest by inducing or activating cdk inhibitors, and by inhibiting factors required for cdk activation. Mechanisms that lead to cell cycle arrest by TGF-β are reviewed. Loss of growth inhibition by TGF-β occurs early in breast cell transformation, and may contribute to breast cancer progression. Dysregulation of cell cycle effectors at many different levels may contribute to loss of G₁ arrest by TGF-β. Elucidation of these pathways in breast cancer may ultimately lead to novel and more effective treatments for this disease.     

Estrogen and antiestrogens alter breast cancer invasiveness by modulating the transforming growth factor-β signaling pathway

In the later stages of breast cancer, estrogen receptor (ER)α-negative cancers typically have higher histological grades than ERα-positive cancers, and transforming growth factor (TGF)-β promotes invasion and metastasis. Our previous study indicated that ERα inhibited TGF-β signaling by inducing the degradation of Smad in an estrogen-dependent manner. In the present study, we report that the suppressive effects of ERα and estrogen on tumor progression are mediated by inhibiting TGF-β signaling. Furthermore, we investigated the effects of antiestrogens such as ICI182,780 (ICI) or tamoxifen (TAM) on TGF-β signaling and breast cancer invasiveness. The levels of total Smad and pSmad were reduced by estrogen, whereas ICI slightly increased them, and TAM had no effect. To investigate the effect of antiestrogens on breast cancer invasiveness, we generated highly migratory and invasive MCF-7-M5 cells. The migration and invasion of these cells were suppressed by the inhibitor of TGF-β receptor kinase, SB-505124, and estrogen. However, antiestrogens did not suppress the migration and invasion of these cells. In addition, we screened TGF-β target genes whose expression was reduced by estrogen treatment and identified four genes associated with breast cancer invasiveness and poor prognosis. The expression of these genes was not decreased by antiestrogens. These observations provide a new insight into estrogen function and the mechanisms underlying estrogen-mediated suppression of tumor progression.     

Transforming growth factor-beta and breast cancer: Tumor promoting effects of transforming growth factor-β

This cross-sectional investigation in Hawaii explored the relation between soy foods and mammographic characteristics using two food frequency questionnaires and a computer-assisted density assessment method. Japanese and Chinese women reported significantly greater soy food intake than Caucasian women. Whereas soy intake and the size of the dense areas were not related, soy intake and percent mammographic densities were positively associated. The size of the entire breast and the nondense area (ie the fatty part of the breast) were inversely related to soy intake. These results suggest the hypothesis that soy foods by themselves or as part of an Asian dietary pattern may affect the growth of the female breast before adulthood, but the possible mechanisms of action have to be explored in future studies.     

Mechanistic basis and clinical relevance of the role of transforming growth factor-β in cancer

Transforming growth factor-β (TGF-β) is a key factor in cancer development and progression. TGF-β can suppress tumorigenesis by inhibiting cell cycle progression and stimulating apoptosis in early stages of cancer progression. However, TGF-β can modulate cancer-related processes, such as cell invasion, distant metastasis, and microenvironment modification that may be used by cancer cells to their advantage in late stages. Corresponding mechanisms include angiogenesis promotion, anti-tumor immunity suppression, and epithelial-to-mesenchymal transition (EMT) induction. The correlation between TGF-β expression and cancer prognosis has also been extensively investigated. Results suggest that TGF-β pathway can be targeted to treat cancer; as such, the feasibility of this treatment is investigated in clinical trials.KEYWORDS : Transforming growth factor-β (TGF-β), neoplasms, prognosis, therapeutics     

Inhibition of hormone-dependent and independent breast cancer cell growthin vivo andin vitro with the antiestrogen toremifene and recombinant human interferon-α2

The antiproliferative action of the antiestrogen toremifene and recombinant human interferon-2a (IFN-2a) were examined on human breast cancer cell lines grown in culture and in the athymic mouse.Solid tumors grew from an inoculation of a 99:1 ratio of hormone dependent (MCF-7) and hormone independent (MDA-MB-231) breast cancer cells without estrogen administration. However, estradiol supplementation significantly increased the rate of tumor growth. The daily administration of 1.35 × 10⁶ U of recombinant human IFN-2a resulted in a marked reduction of tumor growth in both estradiol-treated and non-treated mice. Toremifene administration (130 µg/day from a sustained release preparation) markedly inhibited estradiol stimulation of mouse uterine weight and partially reduced estradiol-stimulated tumor growth. The combination of IFN-2a (1.35 × 10⁶ u/day) with toremifene (130 µg/day) reduced estradiol-stimulated growth much below that of toremifene alone but not below that seen with interferon alone.Toremifene (10^–10-10^–6M) did not inhibit the growth of hormone-independent MDA-MB-231 breast cancer cellsin vitro whereas it did inhibit the growth of hormone-dependent MCF-7 cells in phenol red containing media. IFN-2a (1–10,000 u) inhibited the growth of both MCF-7 and MDA-MB-231 cells in culture; however, MCF-7 cells were approximately 10-fold more sensitive to interferon inhibition. This was consistent with the MCF-7 cells showing a greater sensitivity to interferon than MDA-MB-231 cells in the induction of 25-oligoadenylate synthetase.The heterogeneous tumor model in the athymic mouse suggests that differential sensitivities of breast cancer cells to the antiproliferative actions of interferon may influence the effectiveness of combination therapies.     

On the role of transforming growth factor-β in the growth inhibitory effects of retinoic acid in human pancreatic cancer cells

Background  

Retinoids are potent growth inhibitory and differentiating agents in a variety of cancer cell types. We have shown that retinoids induce growth arrest in all pancreatic cancer cell lines studied, regardless of their p53 and differentiation status. However, the mechanism of growth inhibition is not known. Since TGF-β2 is markedly induced by retinoids in other cancers and mediates MUC4 expression in pancreatic cancer cells, we investigated the role of TGF-β in retinoic acid-mediated growth inhibition in pancreatic cancer cells.     

Role of transforming growth factor-β1 −509 C/T promoter polymorphism in gastric cancer in south Indian population

Tumor Biology - Gastric cancer is a multifactorial disease with the involvement of both genetic and environmental risk factors. Genetic variation in genes encoding cytokines and their receptors...     

Relationship between CCL5 and transforming growth factor-β1 (TGFβ1) in breast cancer

Purpose

Investigate circulating CCL5 in breast cancer patients and healthy controls, along with gene expression levels in corresponding tumour tissue and isolated primary stromal cells. Hormonal control of CCL5, and a potential relationship with TGFβ1, was also investigated.

Methods

Circulating levels of CCL5 and TGFβ1 were measured in 102 breast cancer patients and 66 controls using ELISA. Gene expression levels (CCL5, CCR5, TGFβ1, TGFβRII) were quantified in corresponding tumour tissue (n = 43), normal tissue (n = 16), and isolated tumour (n = 22) and normal (n = 3) stromal cells using RQ-PCR. CCL5 and circulating menstrual hormones (LH, FSH, Oestradiol, Progesterone) were analysed in serum samples from healthy, premenopausal volunteers (n = 60).

Results

TGFβ1 was significantly higher in breast cancer patients (Mean(SEM) 27.4(0.9) ng/ml) compared to controls (14.9(0.9) ng/ml). CCL5 levels decreased in the transition from node negative (59.6(3.7) ng/ml) to node positive disease (40.5(6.3) ng/ml) and increased again as the number of positive lymph nodes increased (?3 positive 50.95(9.8) ng/ml). A significant positive correlation between circulating CCL5 and TGFβ1 (r = 0.423, p < 0.0001) was observed, and mirrored at the gene expression level in tumour tissue from the same patients (r = 0.44, p < 0.001). CCL5, CCR5 and TGFβ1 expression was significantly higher in tumour compared to normal breast tissue (p < 0.001). A significant negative correlation was observed between circulating CCL5, Oestradiol and Progesterone (r = −0.50, r = −0.39, respectively, p < 0.05).

Conclusion

CCL5 expression is elevated in the tumour microenvironment. The data support a role for hormonal control of circulating CCL5 and also highlight a potentially important relationship between CCL5 and TGFβ1 in breast cancer.     

Expression of adhesion molecules and transforming growth factor-β in pleomorphic carcinomas of the lung

Pleomorphic carcinoma (PC) of the lung consists of an epithelial component showing the histology of poorly differentiated non-small cell carcinoma of the lung and a sarcomatous component, that is more aggressive compared to non-small cell carcinoma of the lung. To determine the differences between an epithelial component of PC and poorly differentiated non-small cell carcinoma, the expression of adhesion molecules (E-cadherin, β-catenin and N-cadherin) and transforming growth factor-β (TGF-β) was compared immunohistochemically among 14 poorly differentiated adenocarcinomas of the lung (PDAs) and 14 PCs of the lung, with an epithelial component, showing the histology of PDA. Expression levels of E-cadherin and β-catenin were significantly lower in epithelial or sarcomatous components of PCs than in PDAs while that of TGF-β was significantly higher in epithelial components of PCs than in PDAs. No significant difference was found in incidences of the expression of these molecules between epithelial and sarcomatous components of PCs. No significant difference was noted in the expression level of N-cadherin among PDAs and epithelial and sarcomatous components of PCs. The present results showed that E-cadherin and β-catenin expression is reduced and TGF-β expression is increased in epithelial components of PCs with the same histology as PDA when compared to PDAs, suggesting that an epithelial component of PC is distinct from non-small cell carcinoma with the same histology.     

Essiac® and Flor-Essence® herbal tonics stimulate the in vitro growth of human breast cancer cells

SummaryBackground People diagnosed with cancer often self-administer complementary and alternative medicines (CAMs) to supplement their conventional treatments, improve health, or prevent recurrence. Flor-Essence^? and Essiac^? Herbal Tonics are commercially available complex mixtures of herbal extracts sold as dietary supplements and used by cancer patients based on anecdotal evidence that they can treat or prevent disease. In this study, we evaluated Flor-Essence^? and Essiac^? for their effects on the growth of human tumor cells in culture.Methods The effect of Flor-Essence^? and Essiac^? herbal tonics on cell proliferation was tested in MCF-7, MDA-MB-436, MDA-MB-231, and T47D cancer cells isolated from human breast tumors. Estrogen receptor (ER) dependent activation of a luciferase reporter construct was tested in MCF-7 cells. Specific binding to the ER was tested using an ICI 182,780 competition assay.Results Flor-Essence^? and Essiac^? herbal tonics at 1%, 2%, 4% and 8% stimulated cell proliferation relative to untreated controls in both estrogen receptor positive (MCF-7 and T47D) and estrogen receptor negative (MDA-MB-231 and MDA-MB-436) cell lines. Exposure to the tonics also produced a dose-dependent increase in ER dependent luciferase activity in MCF-7 cells. A 10⁻⁷ M concentration of ICI 182,780 inhibited the induction of ER dependent luciferase activity by Flor-Essence^? and Essiac^?, but did not affect cell proliferation.Conclusion Flor-Essence^? and Essiac^? Herbal Tonics can stimulate the growth of human breast cancer cells through ER mediated as well as ER independent mechanisms of action.     

Serum transforming growth factor-β1 and risk of pancreatic cancer in three prospective cohort studies

Purpose

Clinically evident chronic pancreatitis is a strong risk factor for pancreatic cancer. A small Japanese cohort study previously reported that pre-diagnostic serum transforming growth factor-β1 (TGF-β1) concentration, a potential marker of subclinical pancreatic inflammation, was associated with higher risk of pancreatic cancer. We further explored this association in a larger prospective study.

Methods

Serum TGF-β1 concentrations were measured in pre-diagnostic samples from 729 pancreatic cancer cases and 907 matched controls from a cohort of Finnish male smokers (the Alpa-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study) and two cohorts of US men and women, the Cancer Prevention Study-II and the Prostate Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Multivariable-adjusted odds ratios (ORs) were estimated using conditional logistic regression.

Results

Overall, serum TGF-β1 concentration was not associated with a clear increase in pancreatic cancer risk (OR 1.36, 95 % confidence interval (CI) 0.98–1.88 for highest vs. lowest quintile, p trend = 0.20). However, this association differed significantly by follow-up time (p = 0.02). Serum TGF-β1 concentration was not associated with risk during the first 10 years of follow-up, but was associated with higher risk during follow-up after 10 years (OR 2.13, 95 % CI 1.23–3.68 for highest vs. lowest quintile, p trend = 0.001). During follow-up after 10 years, serum TGF-β1 was associated with higher risk only in the ATBC cohort, although most subjects were from ATBC during this time period and statistical evidence for heterogeneity across cohorts was limited (p = 0.14).

Conclusions

These results suggest that high serum TGF-β1 may be associated with increased risk of pancreatic cancer although a long follow-up period may be needed to observe this association.     

Mesenchymal stem cells play a potential role in regulating the establishment and maintenance of epithelial-mesenchymal transition in MCF7 human breast cancer cells by paracrine and induced autocrine TGF-β

Although the epithelial-mesenchymal transition (EMT) is a normal process that occurs during development, it is thought to be associated with cancer progression and metastasis. Emerging evidence links mesenchymal stem cells (MSCs) in the tumor microenvironment with the occurrence of EMT in cancer progression. In this study, the human breast cancer cell line MCF7 was co-cultured with human adipose-derived MSCs (hAD-MSCs) in a transwell system. Co-cultured cells were analyzed for changes in cellular morphology, EMT markers, protein expression and tumor characteristics. We found that co-cultured MCF7 cells underwent EMT and established a stable mesenchymal phenotype after prolonged co-culturing. Here, we demonstrate that paracrine transforming growth factor-β1 (TGF-β1) secreted by hAD-MSCs regulated the establishment of EMT in MCF7 cells by targeting the ZEB/miR-200 regulatory loop. The downregulation of paracrine TGF-β1 levels can inhibit and reverse the EMT progress by downregulating ZEB1/2 and upregulating miR-200b and miR-200c. The maintenance of a stable mesenchymal state by MCF7 cells required the establishment of autocrine TGF-β signaling to drive and sustain ZEB expression, which had been initiated by the prolonged co-culturing with hAD-MSCs. These results suggest that MSCs may promote breast cancer metastasis by stimulating and facilitating the EMT process.     

Circulating transforming growth factor-β-1 and breast cancer prognosis: results from the Shanghai Breast Cancer Study

Introduction Studies investigating the prognostic effect of circulating TGF-β-1 in breast cancer have given inconsistent findings. The purpose of this study is to evaluate whether circulating transforming growth factor beta 1 (TGF-β-1) is associated with overall and disease-free survival in a cohort of recently diagnosed breast cancer patients. Methods We measured TGF-β-1 levels in plasma samples of breast cancer patients in the Shanghai Breast Cancer Study, a population-based case–control study. We evaluated the relationship between TGF-β-1 levels and overall and disease-free survival. The median follow up time was 7.2 years. Results We observed that, compared with the patients with the lowest quartile of plasma TGF-β-1, patients with the highest quartile of plasma TGF-β-1 had significantly worse overall survival with hazards ratio (HR) = 2.78, with 95% confidence interval (CI): 1.34–5.79 and disease-free survival with HR = 2.49, 95% CI: 1.15–5.41, while the patients with the second and third quartiles of plasma TGF-β-1 did not have significantly different overall and disease-free breast cancer survival. The shape of association between plasma TGF-β-1 levels and breast cancer survival appears to be non-linear. Stratified analysis by stage of disease did not appreciably change the association pattern. Conclusions We conclude that the relationship between circulating levels of TGF-β-1 and prognosis in breast cancer is complex and non-linear. High levels of TGF-β-1 are associated with worse survival independent of stage of disease.     

Inhibition of transforming growth factor-β-activated kinase-1 blocks cancer cell adhesion, invasion, and metastasis

Background:Tumour cell metastasis involves cell adhesion and invasion, processes that depend on signal transduction, which can be influenced by the tumour microenvironment. N-6 polyunsaturated fatty acids, found both in the diet and in response to inflammatory responses, are important components of this microenvironment.Methods:We used short hairpin RNA (shRNA) knockdown of TGF-β-activated kinase-1 (TAK1) in human tumour cells to examine its involvement in fatty acid-stimulated cell adhesion and invasion in vitro. An in vivo model of metastasis was developed in which cells, stably expressing firefly luciferase and either a control shRNA or a TAK1-specific shRNA, were injected into the mammary fat pads of mice fed diets, rich in n-6 polyunsaturated fatty acids. Tumour growth and spontaneous metastasis were monitored with in vivo and in situ imaging of bioluminescence.Results:Arachidonic acid activated TAK1 and downstream kinases in MDA-MB-435 breast cancer cells and led to increased adhesion and invasion. Knockdown of TAK1 blocked this activation and inhibited both cell adhesion and invasion in vitro. Tumour growth at the site of injection was not affected by TAK1 knockdown, but both the incidence and extent of metastasis to the lung were significantly reduced in mice injected with TAK1 knockdown cells compared with mice carrying control tumour cells.Conclusion:These data demonstrate the importance of TAK1 signalling in tumour metastasis in vivo and suggest an opportunity for antimetastatic therapies.     

Prognostic relevance of transforming growth factor alpha (TGF-α) and tumor necrosis factor alpha (TNF-α) detected in breast cancer tissues by immunohistochemistry

Summary The function of different growth factors in the development and progression of malignant tumors and the role of cytotoxic cytokines in the host response generated against neoplasms have been recently studied. Anti-TGF- and anti-TNF- monoclonal antibody families have been developed and characterized previously by our laboratory. Libraries of anti-TGF- and anti-TNF- monoclonal antibodies were selected for equal immunoreactivity both in native (frozen) and in formaldehyde fixed, paraffin embedded histological sections. No differences were found between native and fixed samples demonstrated in 10 cases in the present prospective study. Retrospective investigation was performed in 35 histopathological specimens of breast cancer patients detailed clinically and observed during 5 years after the surgical treatment. Correlation between TGF- and/or TNF- expression and clinical staging - TNM score, lymph node metastasis, tumor recurrence and survival time - was analyzed. According to our present study, the TGF- positive patients had worse clinical prognosis than the TNF- positive and double positive cases during long term observation.     

Silencing of the IKKε gene by siRNA inhibits invasiveness and growth of breast cancer cells

Introduction  

IκB kinase ε (IKKε) is a member of the IKK family that plays an important role in the activation of NF-κB. Overexpressed in more than 30% of breast cancers, IKKε has been recently identified as a potential breast cancer oncogene. The purpose of the present study is to examine the therapeutic potential of IKKε siRNA on human breast cancer cells.