Cells derived from sporadic and AIDS-related Kaposi's sarcoma reveal identical cytochemical and molecular properties in vitro.

We have established 40 cell cultures from biopsies of 5 patients with sporadic Kaposi's sarcoma (KS) and compared them with cell cultures derived from KS biopsies of AIDS patients. Immunocytochemical staining of sporadic KS cells revealed the same endothelial cell markers as those expressed on AIDS-KS cells, indicating that both types of KS might be of endothelial cell origin. In contrast to clinical features, in vitro growth properties showed no differences. KS cells of both types reveal a low degree of malignancy but can be distinguished from fibroblasts by a higher passage number in low serum concentrations and a more pronounced dependence on platelet-derived growth factor (PDGF). The DNA of 12 cell lines of both types of KS was negative for genomic equivalents of hepatitis B virus (HBV), cytomegalovirus (CMV) and, in the case of AIDS-KS, for human immunodeficiency virus (HIV). No rearrangements or amplifications of several oncogenes, often involved in human tumors, were detected. The expression of these oncogenes by sporadic and AIDS-KS cells, as analyzed by Northern blotting, was comparable to that of normal dermal fibroblasts from the same patients. Our results indicate that the 2 types of Kaposi's sarcoma possess identical cytochemical and molecular properties. They are probably weakly malignant neoplasms of endothelial cell origin, and paracrine growth stimulation appears to be important for their maintenance and progression.