Possible relationship between chromosome alterations and in vitro cellular radiosensitivity of human malignant melanoma

In the present study, in vitro radiation survival analysis was performed on 8 human malignant melanoma cell lines with defined karyotypes. Exponentially growing cells were irradiated to doses of 0 to 8 Gy and examined for soft agar clonogenicity. Two groups emerged from this analysis: 4 cell lines with a small shoulder (extrapolation number, n < 2) and 4 cell lines with a large shoulder (n > 2). Of possible significance, 4 4 cell lines with extrapolation numbers > 2 demonstrated clonal structural abnormalities of chromosome 7. In contrast, 3 4 cell lines with extrapolation numbers < 2 had no structural abnormalities of chromosome 7. These very preliminary results suggest that structural alterations of chromosome 7 may be associated with melanoma tumors with high extrapolation numbers.