Clonal cell populations unresponsive to radiosensitization induced by telomerase inhibition

► In our present manuscript, we have clearly showed an interesting but problematic obstacle of a radiosensitization strategy based on telomerase inhibition by showing that: Clonal population unresponsive to this radiosensitization occasionally arise. ► The telomere length of unsensitized clones was reduced, as was that of most sensitized clones. ► The unsensitized clones did not show chromosome end fusion which was noted in all sensitized clones. ► P53 status is not associated with the occurrence of unsensitized clone. ► Telomere end capping in unsensitized clone is operative even under telomerase deficiency.