Histological Study of Murine Fibrosarcoma Treated with Prostaglandin Inhibitors

Abstract

In a previous work we reported that treatment with indomethacin, aspirin and piroxicam in inbred BALB/c mice bearing a transplantable fibrosarcoma induced by methylcholanthrene produced tumor regressions in 45, 32 and 30 per cent of the animals, respectively. In the remaining mice, in which there was no tumor regression, tumor volumes varied (small 0.05<0,5 cm³ medium 0,5<1,35 cm³ and large > 1,35 cm³).

In this histological study we observed that the antitumoral effect of these nonsteroidal antiinflammatory drugs occurred together with a remarkable tumor encapsulation and a decrease in the physical characteristics of malignancy of the tumor cells. The tumor-associated macrophages, which can be detected only by the iron-dextran phagocytosis but not by that of colloidal carbon or trypan blue, were found in the peritumoral area in all cases under study. Their numbers and/or phagocytic capacity were slightly increased in both regressing and small tumors with respect to large, medium and control tumors. These findings suggest that the action of these prostaglandin synthesis inhibiting drugs would permit tumor encapsulation by an improvement in the macrophage-fibroblast relationship together with a decrease in the malignancy of the tumor cells.