PROGNOSTIC RELEVANCE OF C-MYC GENE-EXPRESSION IN GIANT-CELL TUMOR OF BONE

Giant-cell tumor is a primary bone tumor, of uncertain origin, with th e potential capacity to metastasize.;ro study the role of c-myc and c- fos oncogene overexpression in the tumorigenesis and metastatic spread of giant-cell tumors, 32 primary tumors were collected: of these, 19 remained disease-free and 13 metastasized to the lung. Samples of lung metastasis from these 13 patients were also available for study. The expression of c-myc and c-fos mRNA was studied by reverse transcriptio n-polymerase chain reaction and by in situ hybridization. The expressi on of protein was studied by Western blot analysis and by immunohistoc hemistry. C-myc mRNA was overexpressed in 12 (38%) of the 32 primary t umors. Thirteen primary tumors metastasized to the lung; in nine (69%) of these, c-myc mRNA was overexpressed. The c-myc protein was overexp ressed in seven (54%) of the 13 tumors that metastasized to the lung. C-fos was overexpressed in only one lung metastasis. A strong correlat ion between the overexpression of c-m?re and the occurrence of metasta ses was found: thus, c-myc stems a powerful prognosticator in giant-ce ll tumor. C-myc was over-expressed both in giant cells and in mononucl ear cells, suggesting that both cell types are involved in the progres sion of this tumor.