Retention of cellular radiation sensitivity in cell and xenograft lines established from human melanoma surgical specimens

Abstract

Six human melanoma xenograft lines have been established in athymic mice from metastatic lesions in six different patients. Permanent cell lines in monolayer culture have been established from four of the xenograft lines. The cellular radiation sensitivity of the donor patients' tumors, the xenograft lines, and the cell lines were measured in vitro. The Courtenay soft agar colony assay was used for the donor patients' tumors, and a conventional plastic surface colony assay was used for the cell lines, whereas both assays were used for the xenograft lines. The cell survival data were analyzed using the multitarget single-hit as well as the linear-quadratic model. The donor patients' tumors differed considerably in cellular radiation sensitivity (the D0 ranged from 0.85 +/- 0.08 to 1.17 +/- 0.09 Gy, the alpha from 0.25 +/- 0.06 to 0.87 +/- 0.14 Gy-1, and the surviving fraction at 2.0 Gy from 0.15 +/- 0.04 to 0.50 +/- 0.06). The xenograft lines showed similar survival curves in soft agar and on the plastic surface, and the survival curves of a xenograft line and the corresponding cell line were not significantly different. These survival curves were not significantly different from those of the donor patients' tumors, regardless of which survival curve parameter was considered, i.e., the cellular radiation sensitivity of the donor patients' tumors was retained in the cell and xenograft lines. Moreover, the cell and xenograft lines have growth properties in vitro and in vivo that render a wide variety of experiments possible. Consequently, they show great promise for future studies of human tumor radiation biology.