Telomeric associations and consistent growth factor overexpression detected in giant cell tumor of bone

Abstract

Tumor specimens from 15 patients with giant cell tumor (GCT) of bone were cytogenetically analyzed. A subset of five individuals had tumor cells harvested and polyadenylated RNA isolated. Multiple Northern blots were performed utilizing radiolabeled probes for the growth factors TGF beta 1, TGF beta 2, TGF beta 3, and TGF alpha (TGF, transforming growth factor). RNAs from other types of neoplasms and nonneoplastic cells were examined as controls. The most consistent cytogenetic abnormality detected involved multiple telomeric associations (TAs), most frequently involving the terminus of the long arm of chromosome 19 (19q). Northern blot analysis revealed a consistent expression of TGF beta 1 and TGF beta 2 with an inconsistent mRNA expression for the other TGFs. There was a relative overexpression of mRNA for TGF beta 2. The gene location for TGF beta 1 is near the 19q terminus and thus it is speculated that TGF beta may play a role in the neoplastic transformation of GCT.

Figure 1

Representative telomeric associations. Top row from left to right: tas(19;20) (pter;qter), tas(15;19)(qter;qter), and tas(10;19)(pter;qter). Bottom row from left to right: Two ring chromosomes and TAs of four chromosomes from groups D, C, G, and D.

Figure 2

Histogram of giant cell tumors of bone (GCT) involved in at least two telomeric associations (TAs). Eleven of 15 patients demonstrated TAs. The 19q terminus is most frequently involved.

Figure 3

Competitive binding for TGFβ receptor in giant tumor of bone. Increasing amounts of serum-free, acid-activated GCT media were added to ¹²⁵I-labeled TGFβ-saturated receptors on AKR-2B fibroblasts.

Figure 4

Northern blot of AKR-2B fibroblasts and two individuals with giant cell tumors of bone. Two micrograms of polyadenylated RNA were used in all lanes. Lane 1 = rapidly growing AKR-2B fibroblasts. Lane 2 = GCT from patient 7. Lane 3 = GCT from patient 8. The radiolabeled TGFβ1 probe was prepared as previously described by Derynck et al. [24].

Figure 5

Northern blot of giant cell tumor of bone compared to other neoplastic and nonneoplastic cell lines. Four micrograms of tumor and GI epithelium mRNA were used. One microgram of BSC-1 RNA was used. Lane 1 = BSC-1 kidney epithelium. Lane 2 = GCT from patient 7. Lane 3 = GCT from patient 8. Lane 4 = GI epithelium. Lanes 5, 6 = a Panc-1 human pancreatic carcinoma cell line. Lane 7 = Biopsied pancreatic carcinoma cell RNA. The radiolabeled TGFβ2 probe was prepared as previously described [24].

Figure 6

Northern blot of two individuals with giant cell tumors. Two micrograms of tumor RNA were used. Lane 1 = HT 1080. Lane 2 = GCT from patient 11. Lane 3 = GCT from patient 12. The radiolabeled TGFβ2 probe was prepared as previously described by Miller et al. [23].