K. Takahashi et al., REDUCED EXPRESSION OF NEUROFIBROMIN IN THE SOFT-TISSUE TUMORS OBTAINED FROM PATIENTS WITH NEUROFIBROMATOSIS TYPE-1, Clinical science, 88(5), 1995, pp. 581-585
1. We analysed the expression of neurofibromin mRNAs, encoded by the g
ene responsible for neurofibromatosis type 1, and of neurofibromin pro
tein in nine soft tissue tumours by S1 nuclease mapping and Western bl
ot analyses. Four tumours were obtained from patients with neurofibrom
atosis type 1, comprising two neurofibromas, one fibrolipoma and one m
alignant schwannoma, and five neurogenic tumours were obtained from no
n-neurofibromatosis type 1 patients. 2. All tumours, except for a mali
gnant schwannoma, similarly expressed three species of mRNA encoding n
eurofibromin, an isoform with the insertion of 21 amino acids in the d
omain related to ras GTPase-activating protein, and an N-terminal isof
orm lacking this domain. 3. Western blot analysis demonstrated deficie
ncy of neurofibromin in the tumours derived from three out of the four
neurofibromatosis type 1 patients: a fibrolipoma, a malignant schwann
oma and a neurofibroma. In contrast, reduction in neurofibromin was no
t detected in the five tumours obtained from non-neurofibromatosis typ
e 1 patients. Furthermore, the expression of uas GTPase-activating pro
tein was detected in all nine tumours examined. 4. The undetectable or
reduced level of neurofibromin in the tumours obtained from neurofibr
omatosis type 1 patients suggests that this deficiency is closely rela
ted to their tumourigenesis.