Absence of Expression of c-sis and Transforming Growth Factor-β mRNA in Malignant Fibrous Histiocytoma.

Total RNA was extracted from five malignant fibrous histiocytomas and two benign fibrohistiocytic lesions and assayed for mRNA expressions for transforming growth factor beta (TGF-β) and c-sis by Northern blot analysis. Production of both of these has been associated with cells of monocyte-macrophage lineage, and these factors have been shown to be important in physiologic mesenchymal cell proliferation. No mRNA expression of either TGF-β or c-sis was identified in any of the fibrohistiocytic tumor samples. The lack of expression of TGF-β and c-sis may be consistent with a nonhistiocytic origin of malignant fibrous histiocytoma, or may reflect transformation-associated loss of the normal molecular mechanisms of mesenchymal proliferation. The absence of c-sis mRNA expression can be reconciled with the prior immunohistochemical demonstration of platelet-derived growth factor in tumor cells of malignant fibrous histiocytoma. [ABSTRACT FROM AUTHOR]