title: The p75 neurotrophin receptor is widely expressed in conventional papillary thyroid carcinoma.
abstract: Papillary thyroid carcinomas (PTCs) are associated with alterations in several proto-oncogenes related with nervous system development and function, such as TrkA and RET, which are commonly rearranged in these carcinomas. The other oncogenic event recently identified in PTC is the BRAF V600E mutation. Because the role of TrkA was not completely elucidated in thyroid cancer ethiopathogenesis, we decided to study the expression of active, phosphorylated TrkA and of its coreceptor p75 neurotrophin receptor (p75 NTR) in a series of 92 PTC (37 lesions of conventional PTC, 28 of follicular variant of PTC [FVPTC], and 27 of other variants of PTC) as well as in 21 samples of normal thyroid and nonneoplastic thyroid lesions used as a controls. We observed neoexpression of p75 NTR in PTC, particularly in conventional PTC and in other variants of PTC displaying a papillary growth pattern, rather than in FVPTC. No immunoexpression of p75 NTR was observed in normal thyroid nor in nonneoplastic thyroid lesions. The cellular localization of p75 NTR immunoexpression was also significantly associated with the growth pattern of PTC, being much more frequently detected in an apical localization in PTC with papillary architecture than in PTC with a follicular or solid growth pattern. This apical localization of p75 NTR was significantly associated with the presence of BRAF V600E. No significant differences were detected between normal thyroid, nonneoplastic lesions, and PTC (or any PTC variant) regarding expression/activation of TrkA, thus suggesting that by itself and in contrast to p75 NTR, TrkA is not altered during PTC development.
authors.affiliation: IPATIMUP-Institute of Molecular Pathology and Immunology, University of Porto, Porto, Portugal.
authors.forename: Ana Sofia
authors.initials: AS
authors.lastname: Rocha
authors.forename: Björn
authors.initials: B
authors.lastname: Risberg
authors.forename: João
authors.initials: J
authors.lastname: Magalhães
authors.forename: Vitor
authors.initials: V
authors.lastname: Trovisco
authors.forename: Inês Vieira
authors.initials: IV
authors.lastname: de Castro
authors.forename: Philip
authors.initials: P
authors.lastname: Lazarovici
authors.forename: Paula
authors.initials: P
authors.lastname: Soares
authors.forename: Ben
authors.initials: B
authors.lastname: Davidson
authors.forename: Manuel
authors.initials: M
authors.lastname: Sobrinho-Simões
mesh_terms: D000231:Adenocarcinoma, Papillary / Q000378:metabolism* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000378:metabolism; D005819:Genetic Markers; D006801:Humans; D007150:Immunohistochemistry; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism; D020800:Receptor, Nerve Growth Factor / Q000378:metabolism*; D020917:Receptor, trkA / Q000378:metabolism; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D005819:Genetic Markers; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf