Tomás Álvarez Gago

FOXM1 is a molecular determinant of the mitogenic and invasive phenotype of anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma (ATC) is a very aggressive thyroid cancer. forkhead box protein M1 (FOXM1) is a member of the forkhead box family of transcription factors involved in control of cell proliferation, chromosomal stability, angiogenesis, and invasion. Here, we show that FOXM1 is significantly increased in ATCs compared with normal thyroid, well-differentiated thyroid carcinomas (papillary and/or follicular), and poorly differentiated thyroid carcinomas (P=0.000002). Upregulation of FOXM1 levels in ATC cells was mechanistically linked to loss-of-function of p53 and to the hyperactivation of the phosphatidylinositol-3-kinase/AKT/FOXO3a pathway. Knockdown of FOXM1 by RNA interference inhibited cell proliferation by arresting cells in G2/M and reduced cell invasion and motility. This phenotype was associated with decreased expression of FOXM1 target genes, like cyclin B1 (CCNB1), polo-like kinase 1 (PLK1), Aurora B (AURKB), S-phase kinase-associated protein 2 (SKP2), and plasminogen activator, urokinase: uPA (PLAU). Pharmacological inhibition of FOXM1 in an orthotopic mouse model of ATC reduced tumor burden and metastasization. All together, these findings suggest that FOXM1 represents an important player in thyroid cancer progression to the anaplastic phenotype and a potential therapeutic target for this fatal cancer.

Abstract 5505: TERT promoter mutations in primary papillary thyroid carcinomas and matched local / distant metastases

TERT promoter (TERTp) mutations represent a common oncogenic event in sporadic thyroid follicular cell carcinogenesis. Though TERTp mutations have been statistically associated with aggressiveness and metastatic spreading, their involvement in lymph node metastases (LNMs) and / or distant metastases (DMs) development among papillary thyroid carcinoma (PTC) patients remains to be defined. To evaluate the role of TERTp mutations on metastatic tumor expansion, primary tumors (Pt) and matched LNMs and/or DMs were genotyped by means of PCR-direct sequencing in a cohort of 33 patients diagnosed of PTC, which had been previously analyzed for BRAF and RAS mutations. Focal changes in the growth pattern or microscopic grade within the Pt or the metastases were separately genotyped to determine the clonal/subclonal nature of TERTp mutations, their association with particular histological variants of PTC or their presence in intra-tumoral PDC-like foci. Results were correlated with clinico-pathological parameters of pour outcome and survival. The analysis of 99 tumor samples obtained from 33 PTC cases revealed that TERTp mutations were quite common (42.4%).The mutation C228T was much more common than the C250T (78,6% vs 21,4%). TERTp mutations did not correlate with specific PTC subtypes [CL-PTC, FV-PTC or Mixed-PTC] and were subclonal in half of the cases. The mutations segregated to LNMs in 73% of cases [100% CL-PTC and FV-PTC; 57% Mixed PTC]. In 2 Mixed-PTC cases the mutation seemingly originated the novo in the LNM. TERTp mutations were present in all samples of DM. While 71% of the cases mutated at TERTp bore the BRAFV600E mutation, the coexistence of TERTp and RAS mutations was exceptional. TERTp mutations were found to be significantly correlated with age ≥ 45 years old, high grade poorly differentiated PTC foci or nesting-PDC-like foci, stage at diagnosis or at last follow-up and patient status. A trend of correlation with male sex, vascular invasion, tumor recurrence and development of LNM during the follow-up was also seen. Tumor multifocality was inversely correlated with TERTp mutations. The coexistence of TERTp and BRAFV600E mutants did not increase the prognostic power of TERTp mutations alone. All of the patients who died of disease displayed TERTp mutations. Kaplan-Meier analysis revealed that patients with PTC bearing TERTp mutations had a poor prognosis showing a higher tumor recurrence probability [p= 0.0085] and a reduced disease specific survival [p Citation Format: Noa Feas Rodriguez, Miram Corraliza Gomez, Tomas Alvarez Gago, Juan Jose Mateos Otero, Raquel Munoz Martinez, Ginesa Maria Garcia-Rostan. TERT promoter mutations in primary papillary thyroid carcinomas and matched local / distant metastases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5505. doi:10.1158/1538-7445.AM2017-5505

Abstract 4222: Usefulness of VE1 immunohistochemical detection of BRAFV600E in aggressive thyroid cancers (PDCs and UCs)

Activating BRAF mutations are frequent in thyroid follicular cell carcinogenesis. The BRAFV600E point mutation represents the most common oncogenic event in sporadic papillary thyroid cancer (PTC). Although at a much lower frequency the BRAFV600E mutation is also present among less differentiated, more aggressive, I131 resistant forms of thyroid cancer as poorly differentiated carcinomas (PDCs) and undifferentiated carcinomas (UCs). Small molecule inhibitors targeting either the BRAF V600E protein or upstream or downstream kinases involved in MAPK signalling are currently under pre-clinical or clinical investigation in advanced, metastatic, I131 resistant thyroid cancers. Recently, immunohistochemical (IHC) studies on PTCs, using the VE1 mouse anti-human BRAF V600E antibody have shown to be a reliable means for detecting the BRAFV600E mutation in a clinical setting without molecular genotyping units. In this study we sought to determine the usefulness of the VE1 antibody for detecting the BRAF V600E mutant protein in a series of 103 aggressive thyroid cancers (59 PDCs and 44 UCs) previously characterized by PCR-SSCP for the presence of BRAF mutations in exons 11 and 15. The BRAFV600E mutation was present in 10/59 PDCs (17%) and 11/44 UCs (25%). Immunohistochemistry revealed 9 mutated PDCs (sensitivity 90%) and 9 mutated UCs (82% sensitivity). The staining intensity in BRAF V600E mutated samples ranged from weak to strong. Non valuable results were found in 3 PDCs and 4 UCs. Overall the results indicate that immunohistochemistry with VE1 antibody may be an alternative to molecular biology approaches for the routine detection of BRAFV600E point mutations in clinical settings without molecular genotyping facilities. It may help clinicians in targeted therapy decision making. Citation Format: Noa Feas-Rodriguez, Angela M. Costa, Tomas Alvarez Gago, Juan Jose Mateos Otero, Jose Manuel Cameselle Teijeiro, Raquel Munoz, Ginesa Maria Garcia-Rostan. Usefulness of VE1 immunohistochemical detection of BRAFV600E in aggressive thyroid cancers (PDCs and UCs). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4222.