title: Molecular characteristics of papillary thyroid carcinomas without BRAF mutation or RET/PTC rearrangement: relationship with clinico-pathological features.
abstract: About 60-70% of papillary thyroid carcinomas (PTC) present a BRAF(T1799A) gene mutation or a rearrangement of RET gene (RET/PTC). In this study, we examined whether PTC without BRAF(T1799A) mutation and without RET/PTC rearrangement named PTC-ga(-) were distinguishable from PTC-ga(+) (with one or the other gene alteration) on the basis of gene expression characteristics. We analyzed the mutational state of 116 PTC and we compared gene expression profiles of PTC-ga(+) and PTC-ga(-) from data of a 200 gene macroarray and quantitative PCR. Seventy five PTC were PTC-ga(+) and 41 were PTC-ga(-). Unsupervised analyses of macroarray data by hierarchical clustering led to a complete segregation of PTC-ga(+) and PTC-ga(-). In a series of 42 genes previously recognized as PTC 'marker' genes, 22 were found to be expressed at a comparable level in PTC-ga(-) and normal tissue. Thyroid-specific genes, TPO, TG, DIO1, and DIO2 were under-expressed in PTC-ga(+) but expressed at a normal level in PTC-ga(-). A few genes including DUOX1 and DUOX2 were selectively dys-regulated in PTC-ga(-). Tumor grade of PTC-ga(-) was lower than that of PTC-ga(+). There was a strong association between the mutational state and histiotype of PTC; 81% of PTC follicular variants were corresponded to PTC-ga(-), whereas 84% of PTC of classical form were PTC-ga(+). In conclusion, we show that PTC without BRAF(T1799A) mutation or RET/PTC rearrangement, mainly corresponding to follicular variants, maintain a thyroid differentiation expression level close to that of normal tissue and should be of better prognosis than PTC with one or the other gene alteration.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, UMR 664, Lyon F-69372, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Durand
authors.forename: Carole
authors.initials: C
authors.lastname: Ferraro-Peyret
authors.forename: Mireille
authors.initials: M
authors.lastname: Joufre
authors.forename: Annie
authors.initials: A
authors.lastname: Chave
authors.forename: Françoise
authors.initials: F
authors.lastname: Borson-Chazot
authors.forename: Samia
authors.initials: S
authors.lastname: Selmi-Ruby
authors.forename: Bernard
authors.initials: B
authors.lastname: Rousset
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D015153:Blotting, Western; D002291:Carcinoma, Papillary / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002648:Child; D005260:Female; D020869:Gene Expression Profiling; D015321:Gene Rearrangement; D006801:Humans; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics* / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D015514:Oncogene Proteins, Fusion; D011505:Protein-Tyrosine Kinases; C093573:ret-PTC fusion oncoproteins, human; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf