| Popis: |
Multicell spheroids have been shown to survive better than monolayers after irradiation [1,2]. Meanwhile cell lines lacking this “contact-resistance” have been observed. This gave us the possibility to challenge the hypothesis that cells in the spheroids could efficiently cooperate through junctions leading to an enhanced radioresistance. If the hypothesis were correct, only cells developing “contact-resistance” to radiation should form such junctions. We could indeed demonstrate a correlation between “contact-resistance” and the existence of gap-junctions mediating ionic coupling between cells. Several spheroid-forming established cell lines were cultured as monolayers and spheroids [2]. From the cell survival curves obtained after γ-irradiation the quantity ρ=Spheroid dose/Monolayer dose for 50% survival was calculated for each cell line. Ionic coupling and electrical membrane resistance were measured using microelectrode technique [3]. ρ = 1 (no “contact-resistance”) was found for the uncoupled cells, whereas coupled cells yielded values between 2 and 3. Cell cooperation did not correlate with morphology (epitheloid/fibroblastoid), tumorigenicity, doubling time, DNA content, chromosome number and growth medium. |
