The growth and radiation response of an early passage human colon adenocarcinoma grown in monolayer, as spheroids, and in nude mice

WiDr, a human colon adenocarcinoma, was established from an omental metastasis. These cells grow in monolayer, as spheroids, and in nude mice. Moderate differentiation can be seen in spheroids and tumors. The monolayer doubling time is 0.8 days and the initial volume doubling time of spheroids and xenografts are 1.2 and 6.2 days, respectively. Experiments were carried out on passages 28-43 from the original tumor. Spheroid cultures were maintained in Bellco spinner flasks. Tumors appeared between 7-14 days after injecting 10/sup 6/ cells into the axilla of athymic Nu mice with a 93-100% take rate. The radiation response was investigated by an in vitro clonogenic assay on plastic petri dishes. Cells from monolayer cultures were irradiated in suspension. Spheroid cultures were irradiated in Bellco flasks 24 hours after feeding. Tumors (113-268 mm/sup 3/) were irradiated in vivo and in vitro. Preliminary data, under all the conditions examined, indicate that Wi Dr is a relatively radioresistant tumor with a broad shoulder on the survival curve. Spheroid and tumor curves indicate the presence of radioresistant cells. Experiments to establish the causes for differential radiosensitivities under the different growth conditions are in progress