ECE2019 Poster Presentations Thyroid 1 (70 abstracts)
Cofilin is a mediator of RET-promoted medullary thyroid carcinoma cell migration, invasion and proliferation
Elena Giardino 1 , Rosa Catalano 1, , Annamaria Barbieri 1 , Donatella Treppiedi 1 , Federica Mangili 1 , Anna Spada 1 , Maura Arosio 1 , Giovanna Mantovani 1 & Erika Peverelli 1
1Endocrinology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy; 2PhD Program in Endocrinological Science, Sapienza University of Rome, Rome, Italy.
Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor that originates from parafollicular thyroid C cells and accounts for 5% -10% of thyroid cancers. In all inherited cases of MTC, and in about 40% of sporadic cases, activating mutations of the receptor tyrosine kinase proto-oncogene RET are found. Constitutively active RET triggers signaling pathways involved in cell proliferation, survival and motility, but the mechanisms underlying malignant transformation of C-cells have been only partially elucidated. Cofilin is a key regulator of actin cytoskeleton dynamics. A crucial role of cofilin in tumor development, progression, invasion and metastasis has been demonstrated in different human cancers, but no data are available in MTC. Interestingly, RET activation upregulates cofilin gene expression. The aim of this study was to investigate cofilin contribution in invasiveness and growth of MTC cells, and its relevance in the context of mutant RET signaling. We found that cofilin transfection in human MTC cell line TT significantly increased migration (178±44%, P<0.001), invasion (165±28%, P<0.01) and proliferation (146±18%, P<0.001), accompanied by an increase of ERK1/2 phosphorylation (2.2-fold) and cyclin D1 levels (1.4-fold). Accordingly, all these responses were significantly reduced after genetic silencing of cofilin (−55±10% migration, P<0.001, −41±8% invasion, P<0.001, −17±3% proliferation, P<0.001). The inhibition of constitutively active RET in TT cells by both the RET pharmacological inhibitor RPI-1 and the transfection of dominant negative RET mutant (RETΔTK) resulted in a reduction of cofilin expression (−37±8%, P<0.001 and −31±16%, P<0.01, respectively). Furthermore, RPI-1 inhibitory effects on TT cell migration (−57±13%, P<0.01), but not on cell proliferation, were completely abolished in cells transfected with cofilin. In conclusion, these data indicate that an unbalanced cofilin expression, induced by oncogenic RET, contributes to promote MTC invasiveness and growth, suggesting the possibility of targeting cofilin pathway for more effective treatment of MTC.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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