The radiation response of human bladder cancer assessed in vitro or as xenografts in immune-deprived mice.

We have studied the response to radiation of cells derived from transitional cell carcinoma (TCC) of the human bladder. In vitro radiation survival curves for two established cell lines, RT-4 and MGH-U1, and for a cell line HB-10 derived recently from biopsy of a metastatic lymph node were characterized by values of D0 and n in the range of 1.1-1.5 Gy and 2-7 respectively. The oxygen enhancement ratio of HB-10 cells was 2.8. Xenografts derived from the line HB-10 were irradiated in vivo under both aerobic and hypoxic conditions and cell survival was assessed in agar. Both aerobic and hypoxic survival curves were similar to that obtained for irradiation of hypoxic HB-10 cells in culture. Another tumor line, HB-15, derived from a cystoscopic biopsy of primary TCC, was maintained by transplantation of xenografts. Regrowth curves for HB-15 xenografts after radiation doses of 10 or 20 Gy were parallel to the growth curve for untreated controls but with volume reduced by factors of about 5 and 20 respectively. Irradiation of HB-15 xenografts under hypoxic conditions conveyed minimal protection as compared to irradiation in air. We conclude that cells derived from TCC of the human bladder exhibit parameters of radiation survival similar to those of other mammalian cells, and that xenografts derived from such cells contain a high proportion of hypoxic cells.