Shafer S H, Phelps S H, Williams C L
Molecular Pharmacology Laboratory, Guthrie Research Institute, Sayre, PA 18840, USA.
Biochem Pharmacol. 1998 Nov 1;56(9):1229-36. doi: 10.1016/s0006-2952(98)00260-3.
This study investigated the effects of the adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase inhibitors caffeine, theophylline, and 3-isobutyl-1-methyl-xanthine (IBMX) on the proliferation and viability of the small cell lung carcinoma (SCLC) cell lines NCI-H345, NCI-H128, and SCC-9. These effects were correlated with the ability of the drugs to induce intracellular Ca2+ mobilization. Treatment of NCI-H345 cells with caffeine resulted in rapid mobilization of Ca2+, as indicated by Fura-2 fluorescence. Incubation of NCI-H345 cells with 6.25 mM caffeine resulted in a 62% inhibition of [3H]thymidine uptake after 2 hr, indicating reduced DNA synthesis. Incubation with 25 mM caffeine resulted in almost total inhibition of [3H]thymidine uptake after 2 hr. Similar effects on [3H]thymidine uptake were seen upon treatment of NCI-H128 and SCC-9 cells with caffeine; however, these cells did not exhibit caffeine-induced Ca2+ mobilization. Inhibition of DNA synthesis (66-93%) also occurred upon incubation of all cell lines with theophylline and IBMX, which did not mobilize Ca2+. Treatment of NCI-H345, NCI-H128, and SCC-9 cells with caffeine, theophylline, or IBMX markedly reduced cell viability. Levels of cAMP increased in the cells following treatment with caffeine, theophylline, or IBMX, reflecting the ability of these drugs to inhibit cAMP phosphodiesterase. These results suggest that the decrease in DNA synthesis and the subsequent cell death induced by these drugs are due to reduced cAMP phosphodiesterase activity, rather than to changes in intracellular Ca2+. These findings indicate that drugs that alter cAMP signaling pathways are potentially valuable agents to inhibit SCLC survival.
本研究调查了3',5'-环磷酸腺苷（cAMP）磷酸二酯酶抑制剂咖啡因、茶碱和3-异丁基-1-甲基黄嘌呤（IBMX）对小细胞肺癌（SCLC）细胞系NCI-H345、NCI-H128和SCC-9增殖及活力的影响。这些影响与药物诱导细胞内Ca2+动员的能力相关。用咖啡因处理NCI-H345细胞导致Ca2+快速动员，Fura-2荧光显示了这一点。用6.25 mM咖啡因孵育NCI-H345细胞2小时后，[3H]胸苷摄取受到62%的抑制，表明DNA合成减少。用25 mM咖啡因孵育2小时后，[3H]胸苷摄取几乎完全被抑制。用咖啡因处理NCI-H128和SCC-9细胞时，对[3H]胸苷摄取也有类似影响；然而，这些细胞未表现出咖啡因诱导的Ca2+动员。用茶碱和IBMX孵育所有细胞系时，也发生了DNA合成抑制（66 - 93%），且它们未动员Ca2+。用咖啡因、茶碱或IBMX处理NCI-H345、NCI-H128和SCC-9细胞显著降低了细胞活力。用咖啡因、茶碱或IBMX处理后，细胞内cAMP水平升高，反映了这些药物抑制cAMP磷酸二酯酶的能力。这些结果表明，这些药物诱导的DNA合成减少及随后的细胞死亡是由于cAMP磷酸二酯酶活性降低，而非细胞内Ca2+的变化。这些发现表明，改变cAMP信号通路的药物可能是抑制SCLC存活的有价值药物。
