Systemic radiation reaction of tumor cell populations to high dose irradiation

: The work presents the results of the experiments confirming supposition of existence of a protection mechanism opposing hard destruction effects and acting at cell population level. The experiments were carried out with cultures of tumour cells HeLa and DEF 4/21. By technique of hybrid selection in selective HAT medium it was found that radioinduced cell fusion led to formation of viable and clonogenic cell hybrids. By electron microscopic methods, microinjections of fluorescent dye-stuff into cells and autoradiography it was discovered that tight cell communications were formed in irradiated culture before cell fusion. After high dose radiation posterity of survivor cells was by far the most radioresistant comparing with the parent cells and had more greater ability for repopulation. It was supposed that the ability was based on property of rapid transition from mitotic reproduction to non-mitotic division.