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Cytostasis is required for IL‐1 induced nitric oxide production in transformed hamster fibroblasts
Author(s) -
Lavnikova Natasha,
Lakhotia Anand,
Patel Naimish,
Prokhorova Svetlana,
Laskin Debra L.
Publication year - 1996
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199612)169:3<532::aid-jcp13>3.0.co;2-7
Subject(s) - cytostasis , nitric oxide , chemistry , hamster , nitric oxide synthase , omega n methylarginine , cell culture , microbiology and biotechnology , tumor necrosis factor alpha , biology , biochemistry , immunology , cytotoxicity , in vitro , genetics , organic chemistry
Abstract 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‐1α and IL‐1β were found to stimulate nitric oxide production and to reduce 3 H‐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 N G ‐monomethyl‐l‐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‐1α and anti‐lL‐1β antibodies were highly specific and did not cross react, anti‐tumor necrosis factor‐α (TNF‐α) antibody was able to partially suppress activation of STHE cells by both IL‐1α and IL‐1β. These data suggest a potential involvement of endogenous TNF‐α 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 l‐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. © 1996 Wiley‐Liss, Inc.