Increased Cathepsin B Expression in Cultured Tuberous Sclerosis Skin Tumor Cells and Patient Tumor Tissues

In 2012, researchers from the Uniformed Services University of the Health Sciences and the National Heart, Lung, and Blood Institute found that skin tumor cells in patients with tuberous sclerosis complex (TSC) had higher levels of cathepsin B, a protein involved in tissue remodeling, compared to normal fibroblasts. The study involved fibroblasts derived from a TSC periungual fibroma (PF) and normal-appearing skin (NL) from the same patient. The researchers found that PF cells had 1.6-, 2.3-, and 8.3-fold increases in the three forms of cathepsin B. Western blot analysis of TSC skin tumor fibroblasts from 5 patients showed significantly higher levels of active cathepsin B than in paired patient NL fibroblasts. The researchers concluded that TSC skin tumor cells may induce hamartoma morphogenesis through expressing and releasing high levels of cathepsin B.