Heterogeneous Radiation and Heat Sensitivity in Vitro of Human Melanoma Xenograft Lines Established from Different Lesions in the Same Patient

Summary

Human melanoma xenograft lines were established in athymic nude mice (BALB/c-nu/nu/BOM) from the primary tumour (OKL-PRI), a s.c. metastasis (OKL-SCM) and a lymph node metastasis (OKL-LNM) in the same patient. The three lines different in growth rate, melanin content, and radiation and heat sensitivity in vitro. The OKL-PRI line grew more slowly than the OKL-SCM and OKL-LNM lines and was the only line that synthesized significant amounts of melanin. The D₀ values were 0·96 ± 0·07 Gy, 0·87 ± 0·07 Gy and 1·52 ± 0·09 Gy (X-rays); 143 ± 21 min, 109 ± 12 min and 195 ± 40 min (heat, 42·5°C); and 21·3 ± 2·7 min, 15·3 ± 1·7 min and 26·7 ± 3·0 min (heat, 44·5°C) for the OKL-PRI, OKL-SCM and OKL-LNM line, respectively. The ranking of the lines in treatment sensitivity was equal for radiation and heat. The radiation and heat sensitivities were similar to those for cells isolated directly from the surgical specimens of the donor patient. The lines were thus established from a single neoplastic disease without artificial cloning in vitro or in vivo, and the cellular radiation and heat sensitivity did not change during the establishment procedure, suggesting that they constitute a relevant experimental model system for studies of clonal tumour heterogeneity in response to radiation and hyperthermia treatments.