CYTOGENETIC ANALYSES OF A MURINE CARCINOMA CELL-LINE AND 6 METASTATICDERIVATIVES WITH DIFFERENT DEGREES OF RADIORESISTABILITY

We reported that a murine carcinoma (DEN3) and its six pulmonary metas tases (M2, M4C, M4D, M4E, M4F, and MG) exhibited different degrees of radioresistability (On Vitro Cell. Dev. Biol. 26:222-228; 1990). While the M2, M4C, M4E, and M4F cultured cells survived up to 2.5 Gy, the c ells of DENS and M6 tolerated up to 5.0 Gy, and the M4D cells could wi thstand up to 10.0 Gy of X-irradiation. In the present investigation, the cytogenetic features of these cell lines were examined: (a) to det ermine the degree of cytogenetic heterogeneity among these cell lines, and (b) to investigate whether any association between the cytogeneti c anomaly and the degree of radioresistability could be established. H eterogeneous cytogenetic aberrations were detected in all of the above lines. Karyotype analysis of the M4D and M6 cell lines displayed both numerical and structural abnormalities. The gain and loss of chromoso mal copies were observed. Structural aberrations, such as translocatio n and deletion appeared in both cell lines. However, correlation betwe en the cytogenetic abnormality and the degree of radioresistability wa s not demonstrated except for a dramatic reduction in one or more copi es of the X-chromosome that occurred in 86% and 93% of the M6 and M4D cells, respectively. The results suggest heterogeneous cytogenetic abe rrations among these cell lines and a possible association between the loss of X-chromosome and radioresistability of these tumor cells.