Influence of exogenous tRNA on growth of transplantable 32P-induced osteosarcomata

The weights of osteosarcomata that arose 22 days after the s.c. injection of cell suspensions (of whold tumours) that had been exposed in vitro to tRNA were significantly different from the weights of those arising from untreated cells. The tRNA was isolated by phenol extraction and DEAE-cellulose chromatography from eviscerated full-term rat embryos, from rat mesenchymal (granulation) tissue and from rat anaplastic osteosarcomata. Tumours developing from osteosarcoma cells treated with either embryonic or normal mesenchymal tRNA were reduced in weight by 76% and 60% respectively. These effects could not be explained as a toxic consequence, because tumour weight was increased by 128% after exposure of cells to osteosarcoma tRNA. In this osteosarcoma model it appears that tumour weights can be influenced in different ways by tRNA from different sources.