Thompson E A, Moore W M, Sawyer R H
J Natl Cancer Inst. 1980 Aug;65(2):477-83.
Injection of cortisol into BALB/c mice inhibited tritiated thymidine ([3H]dThd) incorporation into ascites cells of lymphosarcoma P1798 but not into cells isolated frm large subcutaneous tumors. The DNA synthetic index (SI), estimated autoradiographically after pulse labeling with [3H]dThd in vitro, was 0.25-0.29 for ascites cells and cells isolated from tumors having a radius squared (r2) less than 200 mm2. Cortisol decreased the SI of ascites cells by 90-95% within 5 hours. Similarly, cortisol decreased the SI of cells from subcutaneous tumors having an r2 less than 90 mm2. Growth and [3H]dThd incorporation were also inhibited by cortisol treatment of tumors with an r2 less than 90 mm2. However, when tumors became larger than 90 mm2, the SI did not decrease after cortisol treatment. Neither growth nor [3H]dThd incorporation was inhibited in tumors with an r2 greater than 90 mm2. These data indicate that tumors of lymphosarcoma P1798 became resistant to cortisol in a size-dependent manner. Loss of sensitivity ws not due to a gradual increase in the percentage of resistant cells.
向BALB/c小鼠注射皮质醇可抑制氚标记胸腺嘧啶核苷（[3H]dThd）掺入淋巴肉瘤P1798的腹水细胞，但不影响从大的皮下肿瘤分离出的细胞。在体外经[3H]dThd脉冲标记后通过放射自显影法估计的DNA合成指数（SI），对于腹水细胞以及从半径平方（r2）小于200 mm2的肿瘤中分离出的细胞而言为0.25 - 0.29。皮质醇在5小时内使腹水细胞的SI降低了90% - 95%。同样，皮质醇使r2小于90 mm2的皮下肿瘤细胞的SI降低。皮质醇处理r2小于90 mm2的肿瘤也会抑制其生长和[3H]dThd掺入。然而，当肿瘤大于90 mm2时，皮质醇处理后SI并未降低。r2大于90 mm2的肿瘤的生长和[3H]dThd掺入均未受到抑制。这些数据表明，淋巴肉瘤P1798的肿瘤对皮质醇产生了大小依赖性耐药。敏感性丧失并非由于耐药细胞百分比的逐渐增加。
