EXPRESSION OF TRANSFORMING GROWTH-FACTOR-BETA AND TRANSFORMING GROWTH-FACTOR-BETA RECEPTORS ON AIDS-ASSOCIATED KAPOSIS-SARCOMA

Several humoral growth factors may contribute to the development and g rowth of AIDS-associated Kaposi's sarcoma (KS), They are either provid ed by chronically activated cells of the immune system or in an autocr ine/paracrine manner by the neoplastic cells themselves, Transforming growth factor beta (TGF-beta) may directly enhance the growth of KS ce lls and tumor matrix formation, To mediate a signal both TGF-beta rece ptors type I and type II (T beta R-I and T beta R-II) have to be expre ssed, We investigated the expression of TGF-beta, TGF-beta receptors t ypes I and II, and endoglin, a nonsignaling-type T beta R-III, by mean s of immunohistochemistry on skin biopsies from patients with AlDS-rel ated KS, We found that the TGF-beta ligand was expressed by KS cells i n 9 of 11 samples, T beta R-II was strongly expressed in 10 of 12 samp les, but none of the investigated tumor samples stained for T beta R-I . Endoglin was weakly expressed on all KS lesions and stained the endo thelium of tumor-associated vessels in 92% of the samples, These findi ngs show that most KS lesions have the ability to produce TGF-beta and that KS cells maintain a high expression of T beta R-II in the absenc e of T beta R-I, which may allow KS to escape growth inhibitory effect s of endocrine or paracrine TGF-beta.