Desmoid-type fibromatosis (DF) is a rare connective tissue disease, characterized by the presence of one or more benign non metastasizing myofibroblastic neoplasms with a high local recurrence rate. DF can be diagnosed at any age in both genders but it is more common in young women.
A minority of DF is inheritable and is associated with mutations of the Adenomatous Polyposis Coli (APC) gene, while most of the DF arises sporadically. On the molecular level, 50-80% of the sporadic DF cases have somatic mutations in the codons encoding serine 41 and threonine 45 in exon 3 of the β-catenin gene, CTNNB1. These sites are required for β-catenin phosphorylation and subsequent degradation. Consequently alterations in these sites lead to the Wnt pathway alteration with β-catenin accumulation and its translocation to the nucleus.
Nuclear β-catenin is detected in almost 90% of the desmoid cells and it is considered a positive marker of DF cells once malignant cell transformation is excluded. In addition to this marker, we recently demonstrated that GSK-3β, also involved in Wnt pathway regulation, translocates in the nucleus of DF cells as well, colocalizing and interacting with β-catenin. This event occurs regardless of the presence of CTNNB1 gene mutations suggesting that the β-catenin/GSK-3β interaction and the nuclear translocation can be unrelated to the genetic alterations of CTNNB1. This led us to formulate the hypothesis that the alteration Wnt/β-catenin signaling pathway in desmoid tumor is modulated by the interaction with microenvironmental factors.
The aim of this project is the identification and the characterization of the microenvironment factors responsible for the proliferation and aggressiveness of DF cells. Since the deregulation of the inflammatory process can lead to aberrant fibroblast activation and accumulation of ECM proteins with subsequent tissue fibrosis that can evolve in fibrotic disease and tumor development, we will focus our attention on the inflammatory and growth factors and their interaction with the Wnt/β-catenin pathway. For this purpose cells derived from desmoid tumor and control cell samples will be incubated with different cytokines, growth factors and hormones. Their effect on the growth rate and aggressiveness will be evaluated by immunofluorescence using specific antibodies for cell cycle markers, for the receptors of the microenvironmental factors, for the proteinases degrading the extracellular matrix, for cysteine proteases and for the markers of the basal membrane, lysosomes and vesicles.
We will use a custom Ion AmpliSeq RNA panel to analyze the gene expression of DF cells under treatment, in particular focusing on genes of the Wnt pathway and of the other correlated pathways. Modulating the microenvironment we expect to identify potential factors that promote the DF tumor growth and aggressiveness. This is a critical milestone in defining the potential targets for a therapy aimed at reducing the proliferation, local aggressiveness and recurrence rate of DF tumors.
This study is part of a long term multidisciplinary research program that is ongoing since 2011 and it aims to improve the knowledge of the Desmoid-type fibromatosis and to identify a viable treatment. To date the study has led to the identification of a second potential positive marker of desmoid tumor cells, the nuclear translocation of GSK-3β.