Flow cytometry evaluation of HeLa S3 cell death induced by gamma-radiation

In this study we followed the effects of radiation on human uterin cervix HeLa S3 cells viability, morphology and DNA structure 2-96 hours after treatment with 2-10 Gy from 60Co gamma radiation source. Staining of cells with Annexin V-FITC and propidium iodide showed very low degree of radiation-induced apoptosis. The prevailing form of HeLa S3 cell death according to flow-cytometry, DNA fragmentation and fluorescent microscopy, was necrosis. The gamma-radiation dose necessary to induce 50% of necrosis (termed DD50) was twice higher compared to dose that induced 50% inhibition of cell proliferation (LD50). These in vitro data suggested, that the increase in radiation dose might eradicate tumor cells, rather than just control their proliferation and growth.