A procedure is described for the selection of glucose uptake mutants based upon radiation suicide of Chinese hamster fibroblasts by 2-deoxy[3H]glucose. In one of these mutants, DS 7, the ability to transport either 2-deoxyglucose or 3-O-methylglucose was decreased to one-fifth to one-fourth. Besides this defect, DS7 produces 1/14th the lactic acid produced by the parent when grown on 5 mM glucose. This block in aerobic glycolysis is due to a mutation that affects the expression of the phosphoglucose isomerase gene because no isomerase activity is detected in cell extracts of DS7. This glycolytic block makes that cell line dependent exclusively on respiration for its energy requirement. Consequently, DS7 survives well after removal of glucose but dies quickly in the presence of oligomycin. The parental line O23 (subclone of CCl39) grows at low serum concentration, is anchorage-independent, and is tumorigenic in nude mice. The derived glycolytic mutant DS7 has retained both the in vitro transformed phenotype (low serum dependence and loss of anchorage dependence) and the tumor-forming capability. The tumor cells derived from the injection of DS7 cells have kept the original glycolytic defect. This finding suggests that the transformed properties (high hexose transport and aerobic glycolysis) that can be uncoupled from abnormal growth control are not necessary for the expression of the malignant phenotype in fibroblasts.
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