Patients with recessive dystrophic epidermolysis bullosa develop squamous-cell carcinoma regardless of type VII collagen expression.

Recent data suggest that individuals with recessive dystrophic epidermolysis bullosa (RDEB) only develop squamous-cell carcinoma (SCC) in the presence of the NC1 domain of type VII collagen. This conclusion was based on experimental work in which cryosections of SCCs from 10 people with RDEB all showed positive type VII collagen immunostaining and observations in a murine model of SCC development in which tumors only occurred using keratinocytes from RDEB subjects that expressed detectable levels of the NC1 domain of the type VII collagen protein. To assess whether the clinical interpretation was valid in another cohort of RDEB patients, we examined expression of type VII collagen in 17 SCC tumors excised from 11 patients.

Stem/progenitor cell-like properties of desmoglein 3dim cells in primary and immortalized keratinocyte lines.

We showed previously that primary keratinocytes selected for low desmoglein 3 (Dsg3) expression levels exhibited increased colony-forming efficiency and heightened proliferative potential relative to cells with higher Dsg3 expression levels, characteristics consistent with a more "stem/progenitor cell-like" phenotype. Here, we have confirmed that Dsg3(dim) cells derived from cultured primary human adult keratinocytes have comparability with alpha(6)(bri)/CD71(dim) stem cells in terms of colony-forming efficiency. Moreover, these Dsg3(dim) cells exhibit increased reconstituting ability in in vitro organotypic culture on de-epidermalized dermis (DED); they are small, actively cycling cells, and they express elevated levels of various p63 isoforms.