Vainio M, Saarinen P, Törnquist K
Department of Biosciences, University of Helsinki, Finland.
J Cell Physiol. 1997 Jun;171(3):336-42. doi: 10.1002/(SICI)1097-4652(199706)171:3<336::AID-JCP12>3.0.CO;2-8.
Adenosine has been shown to modulate cell proliferation in FRTL-5 thyroid cells, although the mechanisms by which this interaction occurs is still unclear. In the present study we investigated the effects of adenosine on the 3H-thymidine incorporation, cell cycle kinetics, and expression of the transcription factor c-Fos in cells stimulated via three different mitogenic pathways, i.e., by thyroid stimulating hormone (TSH) [adenosine 3',5'-cyclic monophosphate(cAMP)], insulin (tyrosine kinase), or phorbol 12-myristate 13-acetate (protein kinase C). Addition of adenosine to cells grown in medium containing hormones and serum did not inhibit the incorporation of 3H-thymidine. If adenosine was added to hormone-deprived cells together with any of the tested mitogens, the stimulation of the 3H-thymidine incorporation was inhibited in a dose-dependent manner. The inhibition was significantly lower when the cells were preincubated with TSH or insulin for 48 h. Flow cytometric studies showed that adenosine evoked an inhibition of the cells in the G0/G1 phase. Submaximal doses of adenosine (10 nM-10 microM) were able to induce c-Fos expression in FRTL-5 cells. However, the mitogen-induced expression of c-Fos was not reduced by maximal dose of adenosine (100 microM). The effect of adenosine on DNA synthesis was not dependent on pertussis toxin-sensitive G-proteins. In addition, adenosine A1- or A2- receptor antagonists did not block the effect of adenosine. The effect of adenosine was abolished by treatment of the cells with adenosine deaminase, suggesting that the observed effect was not mediated by a metabolite of adenosine. The results suggest that adenosine is an effective blocker of mitogen-evoked DNA synthesis of FRTL-5 cells, provided that adenosine is administered simultaneously with the mitogen.
已证实腺苷可调节FRTL - 5甲状腺细胞的增殖，尽管这种相互作用发生的机制仍不清楚。在本研究中，我们研究了腺苷对经由三种不同促有丝分裂途径刺激的细胞中3H - 胸腺嘧啶核苷掺入、细胞周期动力学以及转录因子c - Fos表达的影响，这三种途径分别是促甲状腺激素（TSH）[腺苷3',5'-环磷酸（cAMP）]、胰岛素（酪氨酸激酶）或佛波酯12 - 肉豆蔻酸13 - 乙酸酯（蛋白激酶C）。向含有激素和血清的培养基中生长的细胞添加腺苷，并未抑制3H - 胸腺嘧啶核苷的掺入。如果将腺苷与任何一种受试促有丝分裂原一起添加到激素缺乏的细胞中，3H - 胸腺嘧啶核苷掺入的刺激会以剂量依赖的方式受到抑制。当细胞用TSH或胰岛素预孵育48小时时，这种抑制作用明显降低。流式细胞术研究表明，腺苷可引起G0/G1期细胞的抑制。亚最大剂量的腺苷（10 nM - 10 microM）能够诱导FRTL - 5细胞中c - Fos的表达。然而，最大剂量的腺苷（100 microM）并未降低促有丝分裂原诱导的c - Fos表达。腺苷对DNA合成的影响不依赖于百日咳毒素敏感的G蛋白。此外，腺苷A1或A2受体拮抗剂并未阻断腺苷的作用。用腺苷脱氨酶处理细胞可消除腺苷的作用，这表明观察到的作用不是由腺苷的代谢产物介导的。结果表明，只要腺苷与促有丝分裂原同时给药，腺苷就是FRTL - 5细胞促有丝分裂原诱发的DNA合成的有效阻滞剂。
