OVOL2 impairs RHO GTPase signaling to restrain mitosis and aggressiveness of Anaplastic Thyroid Cancer

Abstract

Background Anaplastic Thyroid Cancer (ATC) is an undifferentiated and aggressive tumor that often originates from well-Differentiated Thyroid Carcinoma (DTC) through a trans-differentiation process. Epithelial-to-Mesenchymal Transition (EMT) is recognized as one of the major players of this process. OVOL2 is a transcription factor (TF) that promotes epithelial differentiation and restrains EMT during embryonic development. OVOL2 loss in some types of cancers is linked to aggressiveness and poor prognosis. Here, we aim to clarify the unexplored role of OVOL2 in ATC. Methods Gene expression analysis in thyroid cancer patients and cell lines showed that OVOL2 is mainly associated with epithelial features and its expression is deeply impaired in ATC. To assess OVOL2 function, we established an OVOL2-overexpression model in ATC cell lines and evaluated its effects by analyzing gene expression, proliferation, invasion and migration abilities, cell cycle, specific protein localization through immunofluorescence staining. RNA-seq profiling showed that OVOL2 controls a complex network of genes converging on cell cycle and mitosis regulation and Chromatin Immunoprecipitation identified new OVOL2 target genes. Results Coherently with its reported function, OVOL2 re-expression restrained EMT and aggressiveness in ATC cells. Unexpectedly, we observed that it caused G2/M block, a consequent reduction in cell proliferation and an increase in cell death. This phenotype was associated to generalized abnormalities in the mitotic spindle structure and cytoskeletal organization. By RNA-seq experiments, we showed that many pathways related to cytoskeleton and migration, cell cycle and mitosis are profoundly affected by OVOL2 expression, in particular the RHO-GTPase pathway resulted as the most interesting. We demonstrated that RHO GTPase pathway is the central hub of OVOL2-mediated program in ATC and that OVOL2 transcriptionally inhibits RhoU and RhoJ. Silencing of RhoU recapitulated the OVOL2-driven phenotype pointing to this protein as a crucial target of OVOL2 in ATC. Conclusions Collectively, these data describe the role of OVOL2 in ATC and uncover a novel function of this TF in inhibiting the RHO GTPase pathway interlacing its effects on EMT, cytoskeleton dynamics and mitosis.

OVOL2 induces autophagy-mediated epithelial-mesenchymal transition by the ERK1/2 MAPK signaling in lung adenocarcinoma

“… 27 Multiple studies have shown that OVOL2, as a transcription factor, inhibits EMT in tumor cells. 22 , 28 , 29 This result is consistent with our research results. In the current work, the downregulation of OVOL2 promoted cell proliferation, migration, invasion, and EMT.…”

“…Previous studies have confirmed that OVOL2 plays an important role in tumor development and metastasis. 20 , 21 , 22 In our study, we first found that the expression level of OVOL2 was significantly reduced in LUAD tumor tissues and negatively correlated with the OS and DFS of patients with LUAD using a large-scale LUAD tissue microarray. Low OVOL2 expression was an independent risk factor in patients with LUAD that had poor prognosis and was significantly associated with clinicopathological features, such as tumor size, LN metastasis, and TNM stage.…”

A Meta-Analysis Approach to Gene Regulatory Network Inference Identifies Key Regulators of Cardiovascular Diseases

“…Furthermore, these genes display enrichment in their regulatory regions for a motif recognized by the transcription factor OVOL2 (Supplementary S1) that is known to be involved in angiogenesis and heart formation [39]. Although there is no data supporting its association with cardiac pathologies, OVOL2 has recently been associated with corneal dystrophy and various types of tumors, such as lung cancer and thyroid cancer [40][41][42]. To the best of our knowledge, its role in cardiac disorders has not been previously reported [39].…”