PDF file - 4.1MB, Cell morphology of desmoid-derived MSC line was polyploid. Morphological features of first passage cells cultured from a DT are shown at low (A), intermediate (B), and high (C) densities. Cells aligned at high density (white arrow) to form sites of extensive cell-cell contact denoting polarity. Clusters of cells at high density spontaneously differentiated into neuronal-like cells (D). Original magnification was 10X.
ARTICLE ABSTRACT
Desmoid tumors are nonmalignant neoplasms of mesenchymal origin that mainly contain fibroblast lineage cells. These tumors often occur in patients with familial adenomatous polyposis (FAP) coli who have germ line mutations in the APC gene. Given emerging data that has implicated multipotent mesencyhmal stromal cells (MSC) in the origin of mesenchymal tumors, we hypothesized that desmoid tumors may arise in patients with FAP after MSCs acquire somatic mutations during the proliferative phase of wound healing. To test this idea, we examined 16 desmoid tumors from FAP-associated and sporadic cases, finding that all 16 of 16 tumors expressed stem cell markers, whereas matching normal stromal tissues were uniformly negative. Desmoid tumors also contained a subclass of fibrocytes linked to wound healing, angiogenesis, and fibrosis. Using an MSC cell line derived from an FAP-associated desmoid tumor, we confirmed an expected loss in the expression of adenomatous polyposis coli (APC) and the transcriptional repressor BMI-1 while documenting the coexpression of markers for chondrocytes, adipocytes, and osteocytes. Together, our findings argue that desmoid tumors result from the growth of MSCs in a wound healing setting that is associated with deregulated Wnt signaling due to APC loss. The differentiation potential of these MSCs combined with expression of BMI-1, a transcriptional repressor downstream of Hedgehog and Notch signaling, suggests that desmoid tumors may respond to therapies targeting these pathways. Cancer Res; 72(1); 346–55. ©2011 AACR.
