[Resistance-suppressing activity of transformed Syrian hamster cells and their ability to metastasize]

Hamster embryo cells spontaneously transformed in vitro (HETr) with low metastatic activity were not capable to depress natural antitumor resistance in vivo in contrast to some other lines of Syrian hamster tumor cells. The resistance, depressing and metastatic activities of HETr parental cells and their variants obtained from lung metastases were studied and compared. The direct correlation was found between the resistance-depressing and metastatic activities of the cell variants studied. Five of eight cell variants obtained from lung metastases ocf HETr were capable to depress natural host resistance to the growth of transplanted tumor cells. They were the most active variants in the lung colonization test. It is suggested that in the course of metastasizing there takes place the selection of the tumor cell variants capable of depressing natural antitumor host resistance.