1996 Volume 58 Issue 10 Pages 1017-1020
To investigate a possible phenotypic modulation, MT-8L and MT-9L cells were induced by in vitro culture of undifferentiated MT-8 and fibrohistiocytic MT-9 cells, which had been established from a rat malignant fibrous histiocytoma (MFH), in the medium containing 10 μg lipopolysaccharide (LPS)/ml. MT-8L and MT-9L gave greater positive reactions for histiocytic lysosomal markers and showed ultrastructures of histiocytic natures. In MT-8L, α-smooth muscle actin-positive myofibroblastic cells also significantly increased in number. MT-8L expressed both histiocytic and myofibroblastic phenotypes. MT-8L-induced tumors consisted mainly of storiform type MFH, differing from undifferentiated sarcoma type induced by MT-8. MT-9L and MT-9 tumors showed a storiform pattern. A phenotypic modulation of MFH cells was easily induced by LPS treatment.