DIFFERENTIAL EXPRESSION BETWEEN PAX-6 AND EN PROTEINS IN MEDULLOBLASTOMA

A collection of 28 medulloblastomas was analyzed for expression of the developmental control genes PAX-6 and EN by immunohistochemical stain ing. Sixteen medulloblastomas expressed both EN and PAX-6 but, when di fferentiation could be assessed in the positive areas, PAX-6 is expres sed in the less differentiated cells. Since Drosophila en encodes a ne gative regulator, we overexpressed the chicken en-1 in retinal pigment ed epithelium cells. This resulted in Pax-6 down regulation. These res ults suggest a regulatory loop between PAX-6 and EN, two molecular mar kers of medulloblastoma.