VARIABLE DRUG SENSITIVITY AND CHROMOSOMAL FEATURES OF A CANCER CLONE

Population analysis was made of a cancer clone derived from a single tumor cell, using a clonal strain of the rat ascites hepatoma, CL-1-AH-66F. The sensitivity to nitrogen mustard N-oxide and chromosomal constitution were studied, after establishing subclonal tumors from the original clone. The results indicated the following facts: 1) The cancer clone is not a uniform but a complex population of cells with different degree of sensitivity to chemicals. 2) The degree of drug sensitivity, either of the original clone or its subclones, fluctuates spontaneously within a certain range during serial animal passage. 3) No specific correlation is found between the degree of drug sensitivity and chromosomal constitution of the subclonal tumors. 4) Transient change in the modal chromosome number and ploidy shift occurred during animal passage.