Molecular analysis of transforming growth factor beta in giant cell tumor of bone

Abstract

Giant cell tumor of bone (GCT) is a primary bone neoplasm with unique cytogenetic findings including telomeric associations. Elevated expression of message RNA for transforming growth factor beta (TGF beta), but not transforming growth factor alpha (TGF alpha), has been reported in this tumor. Further investigation of GCT was undertaken to determine whether genetic loci for TGF beta in GCT patients with and without chromosome abnormalities are altered. Due to the reported TGF beta overexpression in GCT, qualitative and quantitative Southern blot analyses with TGF beta 1 and TGF beta 2 and an internal control probe (p3-21) were performed with tumor DNA and DNA from normal tissue on ten patients with GCT and control individuals. No obvious TGF beta 1 or TGF beta 2 gene alterations were detected. Normal copy numbers were calculated when comparing tumor and normal DNA from GCT patients as well as DNA from control individuals. Abnormal chromosome findings, including telomeric associations, marker chromosome, double minutes, chromosome fragments, ring chromosomes (possibly representing intra-chromosome telomeric associations), and polyploid cells were observed in seven of the ten patients with GCT. Chromosomes 11, 16, 19, 20, and 21 were most commonly observed in telomeric associations, with the terminus of the long arm of chromosome 19 being the most frequent. We conclude that there are no TGF beta 1 or TGF beta 2 gene alterations detected in GCT with the methodologies described, and that telomeric associations are a reproducible cytogenetic characteristic of this neoplasm.

Figure 1

Representative examples of chromosomes showing telomeric associations (top row), ring chromosomes, and an acrocentric marker chromosome (bottom row) from patients with GCT. The chromosome number and the telomere involved are listed to the left of each telomeric association.

Figure 2

Qualitative and quantitative Southern blot analysis with TGFβ1 and p3–21 of tumor DNA digested with TaqI from five patients with GCT as well as DNA from two normal control individuals. A normal allele copy number for TGFβ1 was calculated in DNA isolated from GCT. (A) Lane 1 = DNA from GCT from patient S.S. with normal chromosomes. Lane 2 = DNA from GCT from patient G.L. with abnormal chromosome findings. Lane 3 = DNA from GCT from patient B.P. with normal chromosome findings. Lane 4 = DNA from GCT from patient B.C. with abnormal chromosome findings. Lane 5 = Normal DNA from a control adult woman. Lane 6 = Normal DNA from a control adult man. (B) Lanes 1 and 2 = Normal DNA from a control adult female. Lanes 3 and 4 = Tumor DNA from patient B.H. with abnormal chromosomes. Lanes 5 and 6 = Tumor DNA from patient S.S. with normal chromosomes.

Figure 3

Qualitative and quantitative Southern blot analysis with TGFβ2 and p3–21 of tumor and normal DNA digested with TaqI. No obvious DNA alterations were observed after comparing tumor and normal DNA from the same GCT patients or in comparing DNA from a control individual. Lane 1 = DNA from normal tissue from S.S. Lane 2 = Tumor DNA from patient S.S. Lane 3 = DNA from normal tissue from patient EH. Lane 4 = Tumor DNA from patient F.H. Lane 5 = DNA from normal tissue from patient M.S. Lane 6 = Tumor DNA from patient M.S. Lane 7 = DNA from normal tissue from patient B.H. Lane 8 = Tumor DNA from patient B.H. Lane 9 = Tumor DNA from patient K.W. Lane 10 = DNA from normal tissue from a control adult woman.