1. ¹Department of Medical Biochemistry, Göteborg University, Box 440, SE-405 30 Göteborg, Sweden
2. ²Department of Anatomy and Cell Biology, Bergen University, Bergen, Norway

Correspondence: M Pekny, E-mail: Milos.Pekny@medkem.gu.se

Received 30 August 2002; Revised 19 November 2002; Accepted 9 January 2003.

Abstract

In astrocytic neoplasms, the number of cells expressing glial fibrillary acidic protein (GFAP) is inversely proportional to the extent of anaplasia. The loss of GFAP expression, the principal marker of astroglial cells, in these tumors has been proposed to constitute a step in their development and progression. To test this hypothesis, we crossed p53-negative (p53^-/-) mice, which frequently develop astrocytomas after intrauterine exposure to ethylnitrosourea, with GFAP-negative (GFAP^-/-) mice or GFAP^+/+ controls. Brain tumors of glial origin were found in 12 of 35 GFAP^+/+ p53^-/- mice (34%) and in 11 of 27 GFAP^-/- p53^-/- mice (41%). The two groups did not differ in the age at which tumors were detected or in tumor histology or progression. Thus, the loss of GFAP expression frequently seen in high-grade astrocytomas does not constitute a step in tumor development. Rather, it may represent the undifferentiated state of these cells.