RADIATION RESPONSE OF HUMAN ENDOMETRIAL ADENOCARCINOMA CELLS AND CERVICAL SQUAMOUS-CELL CARCINOMA-CELLS GROWN AS MULTICELLULAR SPHEROIDS AND AS MONOLAYER-CULTURES

The radiation response of the human endometrial adenocarcinoma HEC59 cells and the cervical squamous carcinoma, SKG3a cells, grown both as monolayers and as multicellular spheroids, was studied. A clonogenic assay showed that there was no significant difference between HEC59 and SKG3a cells growing exponentially and in plateau phase as a monolayer culture. However, the HEC59 cells had greater ability for repair following sublethal damage than did the SKG3a cells. After the repair, HEC59 cells showed more radioresistance than SKG3a cells. More striking differences were apparent when the cells were grown as spheroids: larger radiation doses were required to reduce clonogenic cell survival and to cause spheroid shrinkage and spheroid fragmentation in HEC59 cells. Hence, the differences radio-responsiveness between HEC59 and SKG3a cells grown as spheroids were demonstrated more easily than those of the cells grown as a monolayer culture. Therefore, multicellular spheroids may be useful as a means of investigation of slight differences in radioresponsiveness between adenocarcinoma and squamous cell carcinoma.