ABSTRACT
BACKGROUND: Altered microRNA profiles have been observed not only in tumour tissues but also in biofluids, where they circulate in a stable form thus representing interesting biomarker candidates. This study aimed to identify a microRNA signature as a non-invasive biomarker and to investigate its impact on glioma biology. METHODS: MicroRNAs were selected using a global expression profile in preoperative serum samples from 37 glioma patients. Comparison between serum samples from age and gender-matched controls was performed by using the droplet digital PCR. The ROC curve and Kaplan-Meier survival analyses were used to evaluate the diagnostic/prognostic values. The functional role of the identified signature was assessed by gain/loss of function strategies in glioma cells. RESULTS: A three-microRNA signature (miR-1-3p/-26a-1-3p/-487b-3p) was differentially expressed in the serum of patients according to the isocitrate dehydrogenase (IDH) genes mutation status and correlated with both patient Overall and Progression Free Survival. The identified signature was also downregulated in the serum of patients compared to controls. Consistent with these results, the signature expression and release in the conditioned medium of glioma cells was lower in IDH-wild type cells compared to the mutated counterpart. Furthermore, in silico analysis of glioma datasets showed a consistent deregulation of the signature according to the IDH mutation status in glioma tumour tissues. Ectopic expression of the signature negatively affects several glioma functions. Notably, it impacts the glioma invasive phenotype by directly targeting the invadopodia-related proteins TKS4, TKS5 and EFHD2. CONCLUSIONS: We identified a three microRNA signature as a promising complementary or even an independent non-invasive diagnostic/prognostic biomarker. The signature displays oncosuppressive functions in glioma cells and impacts on proteins crucial for migration and invasion, providing potential targets for therapeutic intervention.
Subject(s)
Brain Neoplasms , Circulating MicroRNA , Glioma , MicroRNAs , Humans , Brain Neoplasms/pathology , Biomarkers, Tumor/genetics , Glioma/pathology , MicroRNAs/genetics , Prognosis , Isocitrate Dehydrogenase/genetics , Adaptor Proteins, Vesicular Transport/metabolism , Calcium-Binding ProteinsABSTRACT
The polyphenol epigallocatechin-3-gallate (EGCG), the principal mediator of the green tea, has been known to possess antitumor effect. The endothelin A receptor (ET(A)R)/endothelin-1 (ET-1) axis is overexpressed in ovarian carcinoma representing a novel therapeutic target. In this study, we examined the green tea and EGCG effects on two ovarian carcinoma cell lines, HEY and OVCA 433. EGCG inhibited ovarian cancer cell growth and induced apoptosis that was associated with a decrease in Bcl-X(L) expression and activation of caspase-3. Treatment with green tea or EGCG inhibited ET(A)R and ET-1 expression and reduced the basal and ET-1-induced cell proliferation and invasion. The EGCG-induced inhibitory effects were associated with a decrease of ET(A)R-dependent activation of the p42/p44 and p38 mitogen-activated protein kinases and phosphatidylinositol 3-kinase pathway. Remarkably, EGCG treatment resulted in a lowering of basal and ET-1-induced angiogenesis and invasiveness mediators, such as vascular endothelial growth factor and tumor proteinase activation. Finally, in HEY ovarian carcinoma xenografts, tumor growth was significantly inhibited by oral administration of green tea. This effect was associated with a reduction in ET-1, ET(A)R, and vascular endothelial growth factor expression, microvessel density, and proliferation index. These results provide a novel insight into the mechanism by which EGCG, affecting multiple ET(A)R-dependent pathways, may inhibit ovarian carcinoma growth, suggesting that EGCG may be useful in preventing and treating ovarian carcinoma in which ET(A)R activation by ET-1 plays a critical role in tumor growth and progression.
Subject(s)
Anticarcinogenic Agents/pharmacology , Catechin/analogs & derivatives , Endothelin-1/antagonists & inhibitors , Ovarian Neoplasms/drug therapy , Signal Transduction/drug effects , Tea , Animals , Apoptosis/drug effects , Caspase 3 , Caspases/metabolism , Catechin/pharmacology , Cell Proliferation/drug effects , Endothelin-1/pharmacology , Enzyme Activation/drug effects , Female , Humans , Mice , Mice, Nude , Mitogen-Activated Protein Kinases/metabolism , Neoplasm Invasiveness , Ovarian Neoplasms/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Receptor, Endothelin A/metabolism , Transplantation, Heterologous , Urokinase-Type Plasminogen Activator/antagonists & inhibitors , Vascular Endothelial Growth Factor A/metabolism , bcl-X Protein/metabolismABSTRACT
The green tea polyphenol, epigallocatechin-3-gallate (EGCG), has been shown to prevent cancer; however, a precise mechanism responsible for tumor growth inhibition has not yet been clearly described. The endothelin (ET) A receptor (ET(A)R)/ET-1 autocrine pathway is overexpressed in ovarian carcinoma and triggers tumor growth, neoangiogenesis, and invasion. These latter tumor-promoting effects are mediated through the activation of cyclooxygenase (COX)-1- and COX-2-dependent pathways by ET-1. In the present study, pretreatment of HEY and OVCA 433 ovarian carcinoma cell lines with green tea and EGCG inhibited ET-1/ET(A)R expression, ET(A)R-mediated COX-1/2 mRNA expression, and COX-2 promoter activity. These effects were associated with a significant reduction in the COX-1/2-derived prostaglandin E2 (PGE2) production. These results provide a novel insight into the mechanism by which EGCG, by affecting ET(A)R-dependent COX-1/2 pathways may inhibit ovarian tumors suggesting that EGCG may be useful in preventing and treating ovarian carcinoma in which activation of ET(A)R by ET-1 plays a critical role in tumor growth and progression.