Overexpression of platelet-derived growth factor receptor α in breast cancer is associated with tumour progression

Introduction  

Receptor tyrosine kinases have been extensively studied owing to their frequently abnormal activation in the development and progression of human cancers. Platelet-derived growth factor receptors (PDGFRs) are receptors with intrinsic tyrosine kinase activity that regulate several functions in normal cells and are widely expressed in a variety of malignancies. After the demonstration that gastrointestinal stromal tumours without c-Kit mutations harbour PDGFR-α-activating mutations and that PDGFR-α is also a therapeutic target for imatinib mesylate, the interest for this receptor has increased considerably. Because breast cancer is one of the most frequent neoplasias in women worldwide, and only one study has reported PDGFR-α expression in breast carcinomas, the aim of this work was to investigate the potential significance of PDGFR-α expression in invasive mammary carcinomas.     

Targeting transforming growth factor-β signaling in liver metastasis of colon cancer

Despite a primary tumor suppressor role, there is compelling evidence suggesting that TGF-β can promote tumor growth, invasion and metastasis in advanced stages of colorectal cancer. Blocking these tumor-promoting effects of TGF-β provides a potentially important therapeutic strategy for the treatment of colorectal cancer. However, little is known about how the inhibitors of TGF-β receptor kinases affect colorectal carcinogenesis in vivo. Here, we have observed that a novel dual kinase inhibitor of TGF-β type I and type II receptors, LY2109761, inhibits TGF-β-mediated activation of Smad and non-Smad pathways in CT26 colon adenocarcinoma cells having K-Ras mutation. The inhibitor attenuates the oncogenic effects of TGF-β on cell migration, invasion and tumorigenicity of CT26 cells. Furthermore, LY2109761 decreases liver metastases and prolongs survival in an experimental metastasis model. These findings suggest that the dual kinase inhibitor LY2109761 has potential therapeutic value for metastatic colorectal cancer.     

Cytosolic phospholipase A2-α expression in breast cancer is associated with EGFR expression and correlates with an adverse prognosis in luminal tumours

Background:

The eicosanoid signalling pathway promotes the progression of malignancies through the production of proliferative prostaglandins (PGs). Cytosolic phospholipase A₂α (cPLA₂α) activity provides the substrate for cyclooxygenase-dependent PG release, and we have previously found that cPLA₂α expression correlated with EGFR/HER2 over-expression in a small number of breast cancer cell lines.

Methods:

The importance of differential cPLA₂α activity in clinical breast cancer was established by relating the expression of cPLA₂α in tissue samples from breast cancer patients, and two microarray-based gene expression datasets to different clinicopathological and therapeutic parameters.

Results:

High cPLA₂α mRNA expression correlated with clinical parameters of poor prognosis, which are characteristic of highly invasive tumours of the HER2-positive and basal-like subtype, including low oestrogen receptor expression and high EGFR expression. High cPLA₂α expression decreased overall survival in patients with luminal cancers, and correlated with a reduced effect of tamoxifen treatment. The cPLA₂α expression was an independent predictive parameter of poor response to endocrine therapy in the first 5 years of follow-up.

Conclusion:

This study shows a role of cPLA₂α in luminal breast cancer progression, in which the enzyme could represent a novel therapeutic target and a predictive marker.     

PKCα-induced drug resistance in pancreatic cancer cells is associated with transforming growth factor-β1

Background

Drug resistance remains a great challenge in the treatment of pancreatic cancer. The goal of this study was to determine whether TGF-β1 is associated with drug resistance in pancreatic cancer.

Methods

Pancreatic cancer BxPC3 cells were stably transfected with TGF-β1 cDNA. Cellular morphology and cell cycle were determined and the suppressive subtracted hybridization (SSH) assay was performed to identify differentially expressed genes induced by TGF-β1. Western blotting and immunohistochemistry were used to detect expression of TGF-β1-related genes in the cells and tissue samples. After that, the cells were further treated with an anti-cancer drug (e.g., cisplatin) after pre-incubated with the recombinant TGF-β1 plus PKCα inhibitor Gö6976. TGF-β1 type II receptor, TβRII was also knocked down using TβRII siRNA to assess the effects of these drugs in the cells. Cell viability was assessed by MTT assay.

Results

Overexpression of TGF-β1 leads to a markedly increased invasion potential but a reduced growth rate in BxPC3 cells. Recombinant TGF-β1 protein increases expression of PKCα in BxPC3 cells, a result that we confirmed by SSH. Moreover, TGF-β1 reduced the sensitivity of BxPC3 cells to cisplatin treatment, and this was mediated by upregulation of PKCα. However, blockage of PKCα with Gö6976 and TβRII with siRNA reversed the resistance of BxPC3 cells to gemcitabine, even in the presence of TGF-β1. Immunohistochemical data show that pancreatic cancers overexpress TGF-β1 and P-gp relative to normal tissues. In addition, TGF-β1 expression is associated with P-gp and membranous PKCα expression in pancreatic cancer.

Conclusions

TGF-β1-induced drug resistance in pancreatic cancer cells was associated with PKCα expression. The PKCα inhibitor Gö6976 could be a promising agent to sensitize pancreatic cancer cells to chemotherapy.     

Analyses of microsatellite instability and the transforming growth factor‐β receptor type II gene mutation in sporadic breast cancer and their correlation with clinicopathological features

To determine the incidence of microsatellite instability (MSI) and its relationship with both clinicopathologic parameters and patient survival, 101 cases of breast cancer were investigated. In addition, transforming growth factor (TGF) receptor type II (RII) gene mutation was also examined to clarify the relation to MSI in breast cancer development. MSI and RII gene mutation were screened by single strand conformation polymorphism (SSCP). The mutations of the RII gene were confirmed by a direct sequence. An association between the MSI status and the clinicopathological features was examined to assess the potential of the MSI status as a prognostic indicator in sporadic breast cancer cases. MSI was detected in 12 of 101 (11.9%) breast cancer cases. The positive MSI breast cancer cases showed relatively more advanced disease than negative MSI cases, and also exhibited relatively poorer prognoses. No RII gene mutations were observed in any of the breast cancer cases. Our data suggest that the MSI status may thus be a useful indicator for the prognosis of sporadic breast cancer cases. However, the breast seems to be an infrequent target organ for cancer development through RII gene mutations. As a result, tumor progression through this pathway appears to be related to organ specificity. For positive MSI breast cancers, other target genes therefore still need to be identified.     

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     

Expression of the forkhead transcription factor FOXP1 is associated with that of estrogen receptorβ in primary invasive breast carcinomas

We previously identified a correlation between estrogen receptor alpha (ERα) and the candidate tumour suppressor gene Forkhead Box P1 (FOXP1), whose nuclear protein expression in breast tumours was associated with improved patient survival. However, the expression pattern of FOXP1 in normal breast tissue is more reminiscent of the second receptor, ERβ, which has an emerging role as a tumour suppressor in breast cancer and critically may underlie the ability of some ERα-negative tumours to respond to tamoxifen. In a series of 283 breast cancers, in which ERα-positive tumours were treated with tamoxifen, the nuclear expression of ERβ correlated significantly with ERα (p = 0.004), low-tumour grade (p = 0.008) and nuclear FOXP1 (p = 0.01). High-grade tumours exhibited significantly more cytoplasmic ERβ than the low-grade tumours (p = 0.006). Regression analysis demonstrated that FOXP1 expression was most closely related to nuclear ERβ (p = 0.021). Neither, nuclear or cytoplasmic ERβ expression demonstrated prognostic significance. FOXP1 is not estrogen regulated and silencing FOXP1 expression, using siRNA, did not affect ERα, ERβ or progesterone receptor expression, suggesting ER and FOXP1 co-expression may reflect a common regulatory mechanism.     

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.     

Inactivation of FBXW7/hCDC4-β expression by promoter hypermethylation is associated with favorable prognosis in primary breast cancer

Introduction  

Mutational inactivation of the FBXW7/hCDC4 tumor suppressor gene (TSG) is common in many cancer types, but infrequent in breast cancers. This study investigates the presence and impact of FBXW7/hCDC4 promoter methylation in breast cancer.     

Fibroblast growth factor receptor 4 polymorphism is associated with increased risk and poor prognosis of non-Hodgkin’s lymphoma

Fibroblast growth factor receptor 4 (FGFR4) is expressed in various cell types and plays important roles in regulating immune responses. Evidence has shown that FGFR4 rs351855 (Gly388Arg) polymorphism may act as a risk factor for many diseases. In the current study, we investigated the association between FGFR4 polymorphisms and the susceptibility to non-Hodgkin’s lymphoma (NHL) in the Chinese population. Two polymorphisms in the FGFR4 gene (rs351855G/A and rs147603016G/A) were detected by polymerase chain reaction–restriction fragment length polymorphism in 421 NHL cases and 486 healthy controls. Results showed that prevalence of rs351855AA genotype was significantly increased in patients than in controls (odds ratio [OR]?=?2.02, 95 % confidence interval [CI] 1.91–3.23, P?<?0.001). Similarly, rs351855A allele presented significantly higher numbers in cases compared to healthy donors (49.8 versus 40.1 %, P?<?0.001). Further study revealed that the frequency of the rs351855G/A polymorphism was clearly elevated in cases with B cell subtype than those with T cell subtypes. When analyzing the survival time of NHL patients with FGFR4 rs351855G/A polymorphism, cases with AA genotype had significantly shorter survival time compared to the patients with GG genotype (P?<?0.001) or GA genotype (P?<?0.001). These results suggest that FGFR4 rs351855G/A polymorphism is associated with increased susceptibility to NHL and could be used as a marker for predicting the prognosis of the malignancy.     

SNPs in the transforming growth factor-β pathway as predictors of outcome in advanced lung adenocarcinoma with EGFR mutations treated with gefitinib

BackgroundThe aim of this study was to evaluate whether genetic variations in the transforming growth factor-β (TGF-β) pathway influenced clinical outcome of advanced lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutations treated with gefitinib.Patients and methodsTwo hundred six patients with advanced lung adenocarcinomas were enrolled in this study. EGFR mutation in these tumors was detected. Among them, 106 patients with EGFR mutation and 37 of 100 patients with wild type were treated with gefitinib. Genotype of 33 single-nucleotide polymorphisms (SNPs) from 13 genes involved in the TGF-β signaling pathway was determined, and their association with survival time was analyzed. Univariate and multivariate analyses were carried out to assess the role of biological/clinical parameters in progression-free survival (PFS) and overall survival (OS) using Pearson's χ² test, log-rank test, and Cox proportional hazards model.ResultsAmong SNPs analyzed, multivariate analysis showed the cytidylate and thymidine (CT) genotype of SMAD3: rs11632964 was associated with a longer OS and PFS when the entire cohort of 143 patients were included; the association was significant in the patients with EGFR mutant tumors (30.8 versus 17.5 months; log-rank P = 0.020; and 20.8 versus 9.4 months; log-rank P = 0.001), when compared with patients with wild-type EGFR tumors. In patients with mutant EGFR, the CT genotype of SMAD3: rs11071938 and the cytidylate and cytidylate genotype of SMAD3: rs6494633 were also found to be associated with better PFS. Dual luciferase reporter assays showed gefitinib-resistant PC9/G cells transfected with SMAD3: rs11632964T allelic reporter construct showed significantly lower luciferase activities compared with cells expression C allelic reporter construct. There was significantly decreased expression of SMAD3 and pi-SMAD3 in the PC-9/G cells compared with PC-9.ConclusionsAmong the candidate genes involved in the TGF-β pathway, the polymorphisms of SMAD3 appear to be highly predictive of outcome of patients with lung adenocarcinoma after gefitinib treatment, especially in those with EGFR mutations.     

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.