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Background: The incidence of thyroid cancer is increasing worldwide at an alarming rate. BRAFV600E mutation is described to be associated with a worse prognostic of thyroid carcinomas, as well as extrathyroidal invasion and increased mortality. Objective: To our knowledge, there are no reported studies neither from Morocco nor from other Maghreb countries re- garding the prevalence of BRAFV600E mutation in thyroid carcinomas. Here we aim to evaluate the frequency of BRAFV600E oncogene in Moroccan thyroid carcinomas. Methods: In this Single-Institution retrospective study realized in the Anatomic Pathology and Histology Service in the Mil- itary Hospital of Instruction Mohammed V ‘HMIMV’ in Rabat, we report, using direct genomic sequencing, the assessment of BRAFV600E in 37 thyroid tumors. Results: We detected BRAFV600E mutation exclusively in Papillary Thyroid Carcinomas ‘PTC’ with a prevalence of 28% (8 PTC out 29 PTC). Like international trends, Papillary Thyroid Carcinomas ’PTC’ is more frequent than Follicular Thyroid Carcinomas ‘FTC’ and Anaplastic Thyroid Carcinomas ‘ATC’ (29 PTC, 7 FTC and 1 ATC). Conclusion: Our finding gives to the international community the first estimated incidence of this oncogene in Morocco showing that this prevalence falls within the range of international trends (30% to 90%) reported in distinct worldwide ge- ographic regions. Keywords: Biomarker; BRAFV600E; Thyroid cancer; Morocco.

Background The incidence of thyroid cancer is increasing worldwide at an alarming rate. BRAFV600E mutation is described to be associated with a worse prognostic of thyroid carcinomas, as well as extrathyroidal invasion and increased mortality. Objective To our knowledge, there are no reported studies neither from Morocco nor from other Maghreb countries regarding the prevalence of BRAFV600E mutation in thyroid carcinomas. Here we aim to evaluate the frequency of BRAFV600E oncogene in Moroccan thyroid carcinomas. Methods In this Single-Institution retrospective study realized in the Anatomic Pathology and Histology Service in the Military Hospital of Instruction Mohammed V ‘HMIMV’ in Rabat, we report, using direct genomic sequencing, the assessment of BRAFV600E in 37 thyroid tumors. Results We detected BRAFV600E mutation exclusively in Papillary Thyroid Carcinomas ‘PTC’ with a prevalence of 28% (8 PTC out 29 PTC). Like international trends, Papillary Thyroid Carcinomas ‘PTC’ is more frequent than Follicular Thyroid Carcinomas ‘FTC’ and Anaplastic Thyroid Carcinomas ‘ATC’ (29 PTC, 7 FTC and 1 ATC). Conclusion Our finding gives to the international community the first estimated incidence of this oncogene in Morocco showing that this prevalence falls within the range of international trends (30% to 90%) reported in distinct worldwide geographic regions.

Aims: The BRAFV600E oncogene, reported in 40%–60% of papillary thyroid cancer (PTC), has an important role in the pathogenesis of PTC. It is associated with the loss of thyroid iodide-metabolizing genes, such as sodium/iodide symporter (NIS), and therefore with radioiodine refractoriness. Inhibition of mitogen-activated protein kinase (MAPK) pathway, constitutively activated by BRAFV600E, is not always efficient in resistant tumors suggesting that other compensatory mechanisms contribute to a BRAFV600E adaptive resistance. Recent studies pointed to a key role of transforming growth factor β (TGF-β) in BRAFV600E-induced effects. The reactive oxygen species (ROS)-generating NADPH oxidase NOX4, which is increased in PTC, has been identified as a new key effector of TGF-β in cancer, suggestive of a potential role in BRAFV600E-induced thyroid tumors. Results: Here, using two human BRAFV600E-mutated thyroid cell lines and a rat thyroid cell line expressing BRAFV600E in a conditional manner, we show tha...