We have isolated a cell line (ASMM) by serial passage of cells from explant cultures of an angiosarcoma resected from the calf of a 62 year old female. ASMM has been in continuous culture for over eighteen months (>150 population doublings) and has a Fibroblast-like morphology with a doubling time of approximately 72 h. ASMM has a normal diploid karyology and is unable to generate tumors in nude mice or produce colonies in soft agar. Examination of the cytoskeletal proteins shows both desmin and vimentin and a low level of alpha-smooth muscle actin, which can be upregulated by treatment with TGF beta. Low levels of basal VCAM-1 are significantly upregulated with TNF alpha and reduced by the presence of TCF beta. Basal ICAM-1 is also upregulated with TNF alpha and we show an additional upregulation through TGF beta. ASMM expresses high levels of the hyaluronate receptor CD44, including the variant exons 6, 8 and 10. In addition, ASMM synthesises high levels of hyaluronate (HA), as did the original tumor. Unlike human umbilical vein endothelial cells (HUVECs) these cells were unable to generate capillary-like tubes when seeded onto basement membrane gels, and generated cords of cells containing many synthetic organelles and intermediate filaments. We were unable to detect the expression of factor VIII-related antigen, von Willebrand factor (vWF), CD31 or CD34, and were not able to induce expression of E-selectin after TNF alpha stimulation. In conclusion, this cell line represents a partially transformed population of cells which show characteristics consistent with myofibroblast-like cells. The production of high levels of HA and expression of CD44 may help to explain the high degree of agressiveness of the tumor from which ASMM was derived, as these molecules have been shown to play a role in cell motility and adhesion.

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