[Suppression and activation of proliferative activity of tumor cells of varying degree of malignancy in contact with normal embryonic fibroblasts of Syrian hamster].

The proliferative activity (PA) of in vitro transformed embryo fibroblasts of syrian hamsters and their in vivo selected variants of the different degree of malignancy in the close contact with irradiated normal embryo fibroblasts of Syrian hamster (HEF) has been examined. The obtained data demonstrate that PA of the STHE and it's low malignant variants were considerably inhibited in contact with the normal fibroblasts and this effect was retained or even augmented from the 1st to the 6th days of the experiment. More malignant variant of the STHE STHE-MLN-6 was inhibited by HEF to the less degree, the inhibitory effect was decreasing during the experiment and disappeared to the 6th day. PA of the highly malignant, metastasizing variants STHE-MLN-8 and STHE-75/18 was even less susceptible to the inhibitory effect of the normal HEF and they gained the ability to overcome altogether the inhibitory influence of the normal cells, moreover, their PA was stimulated during 4-6 days of contact with normal ones.