Beta-catenin in Desmoid Tumors: the role of T41A and S45F mutations on gene expression

Desmoids tumors (DTs) are rare mesenchymal infiltrative lesions that exhibit high risk of local recurrence despite surgery with negative margins. Mutations in CTNNB1 gene encoding for β-catenin are typically carried by most sporadic DTs but the evidences in support to the clinical/biological role of these mutations are contrasting. Our work is the first study specifically investigating if mutation type could influence the stability of the β-catenin structure, its affinity for α-catenin, as well as the pattern of gene expression and could in turn guide the behavior of the disease. We selected for this study 33 primary DTs surgically treated at our Institution. All samples had these characteristics: 1) DT diagnosis by an expert pathologist (SP); 2) known CTNNB1 mutational status assessed by direct sequencing as previously described (Colombo et al. Cancer 119; 3696–3702, 2013); 3) availability of the formalin fixed paraffin embedded (FFPE) surgical specimen; 4) availability of RNA amount and quality adequate for molecular analysis. The distribution of mutations was T41A (14 cases), S45F (10 cases), and wt (9 cases).