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  • Author: Clarissa Silva Martins x
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Deison Soares de Lima, Clarissa Silva Martins, Beatriz Maria de Carvalho Paixao, Fernando Colbari Amaral, Leandro Machado Colli, Fabiano P Saggioro, Luciano Neder, Helio Rubens Machado, Anemari Ramos Dinarte dos Santos, Daniel G Pinheiro, Ayrton Custodio Moreira, Wilson Araújo Silva Jr, and Margaret Castro

Background

Although the molecular pathogenesis of pituitary adenomas has been assessed by several different techniques, it still remains partially unclear. Ribosomal proteins (RPs) have been recently related to human tumorigenesis, but they have not yet been evaluated in pituitary tumorigenesis.

Objective

The aim of this study was to introduce serial analysis of gene expression (SAGE), a high-throughput method, in pituitary research in order to compare differential gene expression.

Methods

Two SAGE cDNA libraries were constructed, one using a pool of mRNA obtained from five GH-secreting pituitary tumors and another from three normal pituitaries. Genes differentially expressed between the libraries were further validated by real-time PCR in 22 GH-secreting pituitary tumors and in 15 normal pituitaries.

Results

Computer-generated genomic analysis tools identified 13 722 and 14 993 exclusive genes in normal and adenoma libraries respectively. Both shared 6497 genes, 2188 were underexpressed and 4309 overexpressed in tumoral library. In adenoma library, 33 genes encoding RPs were underexpressed. Among these, RPSA, RPS3, RPS14, and RPS29 were validated by real-time PCR.

Conclusion

We report the first SAGE library from normal pituitary tissue and GH-secreting pituitary tumor, which provide quantitative assessment of cellular transcriptome. We also validated some downregulated genes encoding RPs. Altogether, the present data suggest that the underexpression of the studied RP genes possibly collaborates directly or indirectly with other genes to modify cell cycle arrest, DNA repair, and apoptosis, leading to an environment that might have a putative role in the tumorigenesis, introducing new perspectives for further studies on molecular genesis of somatotrophinomas.

Restricted access

Jose Italo Soares Mota, Rui Milton Patrício Silva-Júnior, Clarissa Silva Martins, Ana Carolina Bueno, Luiz Eduardo Wildemberg, Ximene Lima da Silva Antunes, Jorge Guilherme Okanobo Ozaki, Fernanda Borchers Coeli-Lacchini, Carlos Garcia-Peral, Antonio Edson Rocha Oliveira, Antônio Carlos Santos, Ayrton Custodio Moreira, Helio Rubens Machado, Marcelo Volpon dos Santos, Leandro M Colli, Monica R Gadelha, Sonir Roberto R Antonini, and Margaret de Castro

Objectives

To evaluate how telomere length behaves in adamantinomtous craniopharyngioma (aCP) and if it contributes to the pathogenesis of aCPs with and without CTNNB1 mutations.

Design

Retrospective cross-sectional study enrolling 42 aCP patients from 2 tertiary institutions.

Methods

Clinicopathological features were retrieved from the patient’s charts. Fresh frozen tumors were used for RNA and DNA analyses. Telomere length was evaluated by qPCR (T/S ratio). Somatic mutations in TERT promoter (TERTp) and CTNNB1 were detected by Sanger and/or whole-exome sequencing. We performed RNA-Seq to identify differentially expressed genes in aCPs presenting with shorter or longer telomere lengths.

Results

Mutations in CTNNB1 were detected in 29 (69%) tumors. There was higher frequency of CTNNB1 mutations in aCPs from patients diagnosed under the age of 15 years (85% vs 15%; P = 0.04) and a trend to recurrent disease (76% vs 24%; P = 0.1). No mutation was detected in the TERTp region. The telomeres were shorter in CTNNB1-mutated aCPs (0.441, IQR: 0.297–0.597vs 0.607, IQR: 0.445–0.778; P = 0.04), but it was neither associated with clinicopathological features nor with recurrence. RNAseq identified a total of 387 differentially expressed genes, generating two clusters, being one enriched for short telomeres and CTNNB1-mutated aCPs.

Conclusions: CTNNB1

mutations are more frequent in children and adolescents and appear to associate with progressive disease. CTNNB1-mutated aCPs have shorter telomeres, demonstrating a relationship between the Wnt/β-catenin pathway and telomere biology in the pathogenesis of aCPs.