Dermatopontin Expression Research Articles

Reduced dermatopontin expression is a molecular link between uterine leiomyomas and keloids.

Uterine leiomyomas are prevalent estrogen-responsive clonal tumors, but the specific genetic alterations that contribute to their development have not been elucidated. To identify genes involved in the formation of leiomyomas, we used global expression profiling to compare clonal tumors with normal myometrium. Contrary to expectation, genes involved in estrogen action were not differentially expressed between leiomyoma and normal myometrium. Genes encoding extracellular-matrix proteins were prominently featured, suggesting their involvement in formation of a myofibroblast phenotype. Analysis of the extracellular matrix in the leiomyomas revealed a disordered collagen fibril orientation. Expression of the collagen-binding protein dermatopontin was found to be consistently decreased in leiomyoma by both reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time RT-PCR (mean underexpression = 9.41-fold) regardless of leiomyoma size, leiomyoma location, patient race, and patient age. This expression pattern was observed in 11 subjects and a total of 23 leiomyoma:myometrium pairs. Decreased expression of dermatopontin was also associated with keloid formation, a fibrotic disease that shares epidemiologic similarities with leiomyoma. Immunohistochemical studies of leiomyomas and keloids demonstrated reduced levels of dermatopontin in both tissues. In addition, ultrastructural analysis revealed that the orientation of the collagen fibrils in the keloid tissues strongly resembled that in the leiomyomas. Reduction in dermatopontin was associated with an increase in transforming growth factor-beta3 (TGFB3) mRNA levels in leiomyomas, whereas other genes involved in dermatopontin signaling were not differentially expressed. These findings suggest that leiomyoma development involves a myofibroblast cell phenotype characterized by dysregulation of genes encoding extracellular-matrix proteins. In particular, decreased expression of dermatopontin represents a molecular link between the leiomyoma and keloid phenotypes.

Promoters of leiomyoma: dermatopontin expression in leiomyoma suggests an association between fibroids and keloids

Objective: Uterine leiomyoma place a significant burden on those afflicted as well as on the United States health care system. Fibroids are made up of disordered collagenous tissue and are more prevalent in African Americans compared to Caucasian Americans. Keloids are similarly made up of disordered collagenous tissue and are also more prevalent in African Americans. Despite these similarities, there is no known molecular link between these two diseases. Dermatopontin is a 22KDa extra-cellular protein that can interact with two cell signaling pathways: the integrin system and the TGF β system. Dermatopontin expression is decreased in hypertrophic scars (Kuroda et al., 1999) and in fibroids compared to myometrium using microarray analysis (Tsibris et al., 2002). It is therefore possible that differential expression of dermatopontin is a link between the fibroid and keloid phenotype.

Dermatopontin Expression is Decreased in Hypertrophic Scar and Systemic Sclerosis Skin Fibroblasts and is Regulated by Transforming Growth Factor-β1, Interleukin-4, and Matrix Collagen

Dermatopontin is a recently discovered extracellular matrix protein with proteoglycan and cell-binding properties and is assumed to play important roles in cell-matrix interactions and matrix assembly. In this study we examined the expression of dermatopontin mRNA and protein in skin fibroblast cultures from patients with hypertrophic scar and patients with systemic sclerosis. Dermatopontin mRNA and protein levels were reduced in fibroblast cultures from hypertrophic scar lesional skin compared with fibroblasts from normal skin of the same hypertrophic scar patient. Fibroblast cultures from systemic sclerosis patient involved skin also showed significantly reduced expression of dermatopontin compared with normal skin fibroblasts from healthy individuals. We also investigated the effects of cytokines and matrix collagen on dermatopontin expression in normal cultured fibroblasts. Transforming growth factor-beta1 increased dermatopontin mRNA and protein levels, while interleukin-4 reduced dermatopontin expression. Substrate coated with type I collagen reduced dermatopontin mRNA levels, the reduction being more prominent in three-dimensional collagen matrices. Our results suggest that the decreased expression of dermatopontin is associated with the pathogenesis of fibrosis in hypertrophic scar and systemic sclerosis, and that the effect of the cytokines and matrix collagen on dermatopontin may have important implications for skin fibrosis.