Lavnikova N, Lakhotia A, Patel N, Prokhorova S, Laskin D L
Rutgers University, Piscataway, New Jersey 08855-0789, USA.
J Cell Physiol. 1996 Dec;169(3):532-7. doi: 10.1002/(SICI)1097-4652(199612)169:3<532::AID-JCP13>3.0.CO;2-7.
Interleukin-1 (IL-1) is known to inhibit proliferation in some tumor cells. This proinflammatory cytokine also induces nitric oxide production in a variety of cell types. In the present studies we determined if nitric oxide is involved in IL-1 induced growth inhibition in spontaneously transformed hamster embryonic fibroblasts (STHE cells). Both IL-1 alpha and IL-1 beta were found to stimulate nitric oxide production and to reduce 3H-thymidine (TdR) incorporation in high density cultures of STHE cells. However, maximal cytostasis was observed at least 24 h before significant amounts of nitric oxide accumulated in the cultures. In addition, doses of IL-1 which were too low to stimulate nitric oxide synthesis were effective in inducing cytostasis. Furthermore, in low density cultures of STHE cells, IL-1 inhibited DNA synthesis without inducing nitric oxide production. The nitric oxide synthase inhibitor NG-monomethyl-1-arginine (L-NMMA) had no effect on proliferation of cells plated at low density. In contrast, L-NMMA treatment resulted in a 40-60% reduction in IL-1 induced cytostasis in high density cultures. Neutralizing antibodies to IL-1 were found to completely block IL-1 induced cytostasis and nitric oxide production in cells plated at both densities. Although anti-IL-1 alpha and anti-IL-1 beta antibodies were highly specific and did not cross react, anti-tumor necrosis factor-alpha (TNF-alpha) antibody was able to partially suppress activation of STHE cells by both IL-1 alpha and IL-1 beta. These data suggest a potential involvement of endogenous TNF-alpha in IL-1 induced cytostasis and nitric oxide production. Exponentially growing STHE cells produced six-times less nitric oxide than non-proliferating cells. A ten-fold excess of 1-arginine was found to stimulate nitric oxide synthesis, an action that was independent of the rate of cellular proliferation. Taken together these data suggest that nitric oxide is not a major mediator of IL-1 induced cytostasis in STHE cells. Moreover, cytostasis appears to be required for nitric oxide synthesis in these cells.
白细胞介素-1（IL-1）已知可抑制某些肿瘤细胞的增殖。这种促炎细胞因子还可诱导多种细胞类型产生一氧化氮。在本研究中，我们确定一氧化氮是否参与IL-1诱导的自发转化仓鼠胚胎成纤维细胞（STHE细胞）的生长抑制。发现IL-1α和IL-1β均能刺激一氧化氮产生，并减少STHE细胞高密度培养物中3H-胸腺嘧啶核苷（TdR）的掺入。然而，在培养物中积累大量一氧化氮之前至少24小时观察到最大细胞生长停滞。此外，剂量过低而无法刺激一氧化氮合成的IL-1在诱导细胞生长停滞方面是有效的。此外，在STHE细胞的低密度培养物中，IL-1抑制DNA合成而不诱导一氧化氮产生。一氧化氮合酶抑制剂NG-单甲基-L-精氨酸（L-NMMA）对低密度接种的细胞增殖没有影响。相比之下，L-NMMA处理导致高密度培养物中IL-1诱导的细胞生长停滞减少40%-60%。发现针对IL-1的中和抗体可完全阻断两种密度接种的细胞中IL-1诱导的细胞生长停滞和一氧化氮产生。尽管抗IL-1α和抗IL-1β抗体具有高度特异性且不发生交叉反应，但抗肿瘤坏死因子-α（TNF-α）抗体能够部分抑制IL-1α和IL-1β对STHE细胞的激活。这些数据表明内源性TNF-α可能参与IL-1诱导的细胞生长停滞和一氧化氮产生。指数生长的STHE细胞产生的一氧化氮比非增殖细胞少六倍。发现过量十倍的L-精氨酸可刺激一氧化氮合成，这一作用与细胞增殖速率无关。综上所述，这些数据表明一氧化氮不是STHE细胞中IL-1诱导的细胞生长停滞的主要介质。此外，这些细胞中的一氧化氮合成似乎需要细胞生长停滞。
