Increased expression of GEF-H1 in thyorid cancer promotes cell proliferation, migration and invasion

Abstract

RhoGTPases family is involved in several biological process includ- ing gene transcription, cell polarity, migration, and invasion. RhoGT- Pases switch between on and off states and are regulated by several GEFs (activators) and GAPs/RhoGDIs (inactivators). We identified a GEF-H1 as one of the main activators of RhoA. In addition, we have observed that GEF-H1 is involved in cell proliferation, cytoskeleton remodelling, cell migration and invasion, as well as in breast tumor development and metastasis. Rho GTPases contribute to tumor ini- tiation and progression, however, the role of RhoA activators has not yet been study in thyroid cancer (TC). Hence, the aim of this work is to study the role of GEF-H1 in TC development. TC is the most prevalent endocrine neoplasia and the main cause of death is the metastasis. By bioinformatics analysis we found GEF-H1 mRNA and protein overexpressed in tumoral thyroid tissue (TT) compared with non-tumoral tissue (NT). In addition, the expression of GEF-H1 was significantly higher in papillary and anaplastic thyroid carcino- mas than in NT (p<0.05) and increased in papillary carcinomas with lymph node invasion and/or metastasis (p<0.0001). We observed by immunostaining a significant increase in GEF-H1 protein expression in TC human biopsies compared with NT (n=89, p<0.0001). In ad- dition, we observed by immunofluorescence staining high GEF-H1 protein expression in thyroid primary carcinoma cell culture com- pared with normal thyroid cells. To further study the role of GEF-H1 in tumor development, we generated GEF-H1-knock out (KO) cells using CRISPR/Cas9 technology from a thyroid papillary carcinoma cell line (TPC-1). A decrease in proliferation, migration and invasion rates was observed in GEF-H1-KO cells compared to wild type cells. Our results suggest that GEF-H1 could be used as a potential tumor biomarker and/or therapeutic target in TC, since it could be involved in controlling cell proliferation, migration, and invasion of TC cells.