Stevens J, Stevens Y W
Cancer Res. 1975 Aug;35(8):2145-53.
Events preceeding the cortisol inhibition of uridine utilization by corticoid-sensitive P1798 lymphocytes have been investigated. When tumor cells were incubated with 1 muM cortisol for 15 min and then washed free of steroid and reincubated in the absence of hormone, the expected decrease of uridine uptake failed to appear 1.5 hr later. In contrast, the removal of cortisol after 30 or 60 min did not prevent subsequent development of the steroid effect. Addition of actinomycin D with cortisol, or 15 min after hormone treatment was started, blocked steroid action. However, when actinomycin D was added 30 or 60 min after the initial exposure to cortisol, hormone-induced depression of uridine uptake was no longer prevented. To study the role of protein synthesis, cycloheximide was added to the tumor cell suspensions at various times after cortisol treatment was started. Cortisol suppression of uridine utilization was blocked when cycloheximide was added with the hormone or 30 min after the start of hormone treatment. Cycloheximide added together with cortisol and washed out with the steroid after 30 min did not prevent subsequent appearance of decreased nucleoside uptake. Hydroxyurea, an inhibitor of DNA synthesis, did not prevent cortisol action, even when present throughout a 2 hr exposure to the steroid. Hormone removal or actinomycin D addition after 1.5 to 2 hr (when uridine uptake was already inhibited about 25%) did not prevent intensification of the steroid effect during a subsequent 1.5- to 2-hr incubation period, while addition of cycloheximide at this time completely prevented its progression. These results suggest aht: (a) cortisol inhibition of uridine uptake by P1798 lymphocytes involves an early irreversible step and appears to require continuing RNA but not protein synthesis during the first 15 to 30 min of hormone action; (b) protein synthesis but not RNA synthesis is required between 30 and 60 min; and (c) continuing protein synthesis but not RNA synthesis or hormone presence is necessary for the preestablished cortisol effect to progress.
对皮质激素敏感的P1798淋巴细胞中，皮质醇抑制尿苷利用之前发生的事件进行了研究。当肿瘤细胞与1μM皮质醇孵育15分钟，然后洗去类固醇并在无激素条件下重新孵育时，1.5小时后预期的尿苷摄取减少并未出现。相反，在30或60分钟后去除皮质醇并不能阻止随后类固醇效应的发展。在加入皮质醇的同时或激素处理开始15分钟后加入放线菌素D，会阻断类固醇作用。然而，当在最初接触皮质醇30或60分钟后加入放线菌素D时，激素诱导的尿苷摄取抑制不再被阻止。为了研究蛋白质合成的作用，在皮质醇处理开始后的不同时间，将环己酰亚胺加入肿瘤细胞悬液中。当环己酰亚胺与激素一起加入或在激素处理开始30分钟后加入时，皮质醇对尿苷利用的抑制被阻断。与皮质醇一起加入并在30分钟后与类固醇一起洗去的环己酰亚胺并不能阻止随后核苷摄取减少的出现。羟基脲，一种DNA合成抑制剂，即使在整个2小时的类固醇暴露过程中都存在，也不能阻止皮质醇的作用。在1.5至2小时后（此时尿苷摄取已经被抑制约25%）去除激素或加入放线菌素D，并不阻止在随后的1.5至2小时孵育期内类固醇效应的增强，而此时加入环己酰亚胺则完全阻止了其进展。这些结果表明：(a)皮质醇对P1798淋巴细胞尿苷摄取的抑制涉及一个早期不可逆步骤，并且在激素作用的最初15至30分钟内似乎需要持续的RNA合成但不需要蛋白质合成；(b)在30至60分钟之间需要蛋白质合成但不需要RNA合成；(c)预先建立的皮质醇效应的进展需要持续的蛋白质合成，但不需要RNA合成或激素存在。
