58495

OVOL2

BACKGROUND: Associated with recent achievements in therapy for advanced lung adenocarcinoma, there will still be an unmet medical need for effective treatment of stage IIIb/IV, and the prognosis of lung cancer is not optimistic till now. OBJECTIVE: In order to obtain some essential evidences for a potential targeted therapy in lung adenocarcinoma, the effects of Ovol2 gene on epithelial-to-mesenchymal transition (EMT) was observed and the probable mechanisms were analyzed. METHODS: Ovol2 expression was previously evaluated by immunochemistry in lung adenocarcinoma tissue, and Ovol2 was overexpressed by lentivirus infection in A549 cells. Subsequently, the migration and invasion ability of A549 cells was tested by Transwell and Wound healing experiments. The mRNA level of genes correlated to EMT was detected by Real-time PCR, and the expression of reasonable makers was probed by Western Blot. Finally, rescue experiment, Luciferase assay, and chromatin immunoprecipitation assay were performed to explore the probable mechanisms. RESULTS: After treated with Ovol2 overexpression, the expression level of E-cadherin was increased, while the expression level of Vimentin and Twist1 was declined not only in the mRNA level but also in the protein level. Moreover, we found that Ovol2 represses transcription of Twist1 by binding to its promoter directly. Wound healing and Transwell assays indicate that the migration and invasion ability were downregulated by Ovol2 in A549 cells. CONCLUSION: Ovol2 can suppress migration and invasion ability of A549 cells, and prevent EMT by inhibition of Twist1 transcription directly.CI - Copyright (c) 2016. Published by Elsevier B.V.

Great progress has been achieved in the study of the role of TGF-beta signaling in triggering epithelial-mesenchymal transition (EMT) in a variety of cancers; however, the regulation of TGF-beta signaling during EMT in mammary tumor metastasis has not been completely defined. In the present study, we demonstrated that OVOL2, a zinc finger transcription factor, inhibits TGF-beta signaling-induced EMT in mouse and human mammary tumor cells, as well as in mouse tumor models. Data from the Oncomine databases indicated a strong negative relationship between OVOL2 expression and breast cancer progression. Moreover, our experiments revealed that OVOL2 inhibits TGF-beta signaling at multiple levels, including inhibiting Smad4 mRNA expression and inducing Smad7 mRNA expression, blocking the binding between Smad4 and target DNA, and interfering with complex formation between Smad4 and Smad2/3. These findings reveal a novel mechanism that controls the TGF-beta signaling output level in vitro and in vivo. The modulation of these molecular processes may represent a strategy for inhibiting breast cancer invasion by restoring OVOL2 expression.

Rationale: Metastasis is the leading cause of disease-related death among patients with nasopharyngeal carcinoma (NPC). Mounting evidence suggest that epithelial-mesenchymal transition (EMT) is crucial for cancer cells to acquire metastatic ability. In this study, we aim to clarify the extent to which EMT is involved in various cancer properties and identify novel markers for predicting the prognosis of NPC patients. Methods: Two cellular models derived from the same NPC cell line with distinct metastasis ability were used for microarray analysis to identify key transcriptional factors that drive metastasis. Cell migration and invasion were analyzed by wound healing and Transwell analysis. Lung metatasis was determined by tail vein injection assay. cancer stemness was analyzed using colony formation and xenograft assay. The EMT extent was evaluated using immunoblotting, RT-qPCR and immunofluorescence of EMT markers. The value of OVOL2 in prognosis was determined by immunohistochemistry in NPC biopsies. Results: OVOL2 was the most significantly down-regulated EMT transcription factor (EMT-TF) in cellular models of NPC metatasis. Low levels of OVOL2 were associated with poor overall survival of NPC patients and the reduced expression is partly due to promoter methylation and epithelial dedifferentiation. Knockout of OVOL2 in epithelial-like NPC cells partially activates EMT program and significantly promotes cancer stemness and metastatic phenotypes. Conversely, ectopically expression of OVOL2 in mesenchymal-like cells leads to a partial transition to an epithelial phenotype and reduced malignancy. Reversing EMT by depleting ZEB1, a major target of OVOL2, does not eliminate the stemness advantage of OVOL2-deficient cells but does reduce their invasion capacity. A comparison of subpopulations at different stages of EMT revealed that the extent of EMT is positively correlated with metastasis and drug resistance; however, only the intermediate EMT state is associated with cancer stemness. Conclusion: Distinct from other canonical EMT-TFs, OVOL2 only exhibits modest effect on EMT but has a strong impact on both metastasis and tumorigenesis. Therefore, OVOL2 could serve as a prognostic indicator for cancer patients.

epithelial cells possess remarkable plasticity, having the ability to become mesenchymal cells through alterations in adhesion and motility (epithelial-to-mesenchymal transition [EMT]). However, how epithelial plasticity is kept in check in epithelial cells during tissue development and regeneration remains to be fully understood. Here we show that restricting the EMT of mammary epithelial cells by transcription factor Ovol2 is required for proper morphogenesis and regeneration. Deletion of Ovol2 blocks mammary ductal morphogenesis, depletes stem and progenitor cell reservoirs, and leads epithelial cells to undergo EMT in vivo to become nonepithelial cell types. Ovol2 directly represses myriad EMT inducers, and its absence switches response to TGF-beta from growth arrest to EMT. Furthermore, forced expression of the repressor isoform of Ovol2 is able to reprogram metastatic breast cancer cells from a mesenchymal to an epithelial state. Our findings underscore the critical importance of exquisitely regulating epithelial plasticity in development and cancer.CI - Copyright (c) 2014 Elsevier Inc. All rights reserved.