Overexpression of MLH-1 and psoriasin genes in cutaneous angiofibromas from tuberous sclerosis complex patients.

Background: Tuberous sclerosis complex (TSC) is associated with mutations in two likely tumor-suppressor genes (TSC1 and TSC2) and characterized by the development of tumor-like growths (angiofibromas) in a variety of tissues and organs, particularly brain and skin. Methods: Employing a DNA-microarray assay, able to detect mRNA production from 1176 different basic genes, we analyzed the geneexpression levels in a cutaneous hamartoma sample from a TSC patient. Altered gene expressions detected by microarray technology were further checked by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) in the same material and in cutaneous hamartoma samples obtained from five other TSC patients. Results: The results obtained by the microarray technology in one hamartoma specimen, confirmed by the RT-PCR results obtained in the same material and in five other hamartoma specimens, demonstrated that TSC-related angiofibromas exhibit significant mRNA overexpression of two genes, represented by MLH-1 and psoriasin. Conclusions: The overexpression of MLH-1, which codes for a DNA mismatch repair protein, and psoriasin, which codes for a specific chemoattractant factor for CD4þ T cells, implicated in the pathogenesis of inflammatory skin disease, and expressed in excess during abnormal pathways of cell growth, may shed light on the pathogenesis of the proliferative skin lesion.