SPINDLE CELLS ISOLATED FROM KAPOSIS SARCOMA-LIKE LESIONS OF BKV TAT-TRANSGENIC MICE COEXPRESS MARKERS OF DIFFERENT CELL-TYPES/

Objective: To characterize murine spindle cells isolated from Kaposi's sarcoma-like skin lesions developed in BK virus (BKV)/tat-transgenic mice. Methods: Kaposi's sarcoma-like spindle cells isolated from the l esions were propagated in vitro, and their phenotype was investigated using a panel of antibodies against various cell markers and angiogeni c factors. Immunofluorescence and Western blot techniques were used. R esults: We observed co-expression of antigens specific for endothelial , smooth muscle and antigen-presenting cells, suggesting that cells fr om the TTB cell line represent poorly differentiated vascular precurso rs. Since TTB cells were derived from highly vascularized skin lesions , it is noteworthy that they synthesize a complex mixture of angiogeni c factors, including fibroblast growth factor-2, vascular endothelial growth factor, placental growth factor, and hepatocyte growth factor. Due to their role in invasiveness and angiogenesis, we also observed t he expression of urokinase plasminogen activator (uPA), uPA receptor, and plasminogen activator inhibitor-type 1 by TTB cells. Conclusions: Our results suggest that TTB cells share several features with human K aposi's sarcoma spindle cells and can be a useful in vitro system to s tudy the molecular mechanisms involved in Kaposi's sarcoma pathogenesi s. Moreover, they synthesize a complex mixture of angiogenic factors a nd are growth-inhibited by the antiangiogenic drug AGM-1470.