Ganglioside composition in experimental tumors with different growth properties.

The composition of gangliosides was studied in four fibrosarcomas (FL, FLA, FLB, FLC) induced in the Lewis rat by Ferridextran, and in two clones of a spontaneous Lewis rat mammary sarcoma (C-1-SAM LEW and C-2-SAM LEW) and two supertransformed clones (S-174 and S-271) derived from these clones, using the B77 virus. The malignancy of the Lewis tumors was tested in terms of their ability to outgrow the RT-5 barrier in LEW.1x rats and expressed as the loss-rate of LEW.1x rats. As for the Ferridextran-induced tumors, the FL was the only one to have been rejected in nearly 100% of the LEW.1x recipients. Following presensitization with FL the other tumors were also rejected, though not at a rate of 100%. The rat loss-rate was: FL--0%, FLC--23.5%, FLB--36.5%, and FLA--82.6%. As malignancy increased, the composition of gangliosides showed signs of progressive simplification indicating a step-by-step repression of ganglioside biosynthesis involving first the disialoganglioside and subsequently also the monosialoganglioside pathways. Some less distinct decrease (but significant at the 5% level of probability) of gangliosides of the disialoganglioside pathway and an increase of the simplest ganglioside (GM3) were observed between the C-1 clone of SAM LEW and its S-174 supertransformant. However, the changes, especially in the C-2 clone and its supertransformant, were not such as would suggest a marked defect in the biosynthesis of gangliosides.