Thomsen L L, Baguley B C, Wilson W R
Cancer Research Laboratory, University of Auckland School of Medicine, New Zealand.
Cancer Chemother Pharmacol. 1992;31(2):151-5. doi: 10.1007/BF00685103.
Flavone-8-acetic acid (FAA) and its more dose-potent analogue 5,6-dimethylxanthenone-4-acetic acid (5,6-MeXAA), appear to exert their antitumor effects through vascular and other host-mediated mechanisms and are known to induce the synthesis of nitric oxide by murine macrophages. We investigated the role of nitric oxide in the cytotoxic effects of these drugs in host-cell-infiltrated spheroids. EMT6 murine mammary adenocarcinoma cells were grown in culture to produce multicellular spheroids in vitro spheroids), which were then inoculated i.p. into mice. After 6 days the spheroids were removed ex vivo spheroids). Exposure to FAA (890 microM) and 5,6-MeXAA (80 microM) in vitro for 20 h increased nitrite concentrations to 6.7 and 9.7 nmol/spheroid, respectively, as compared with 0.7 nmol/spheroid in the absence of drug. FAA and 5,6-MeXAA did not increase nitrite production in in vitro spheroids in cells obtained by peritoneal lavage. However, mixed cultures of in vitro spheroids and peritoneal cells treated with 5,6-MeXAA produced nitrite (2.4 nmol/spheroid), indicating that interactions between host cells and tumour cells were important for induction. The effects of these drugs on ex vivo spheroids were prevented by co-incubation with NG-monomethyl-L-arginine, indicating that nitrite originated from the oxidation of L-arginine to nitric oxide. Cell sorting of disaggregated spheroids into EMT6 cells and Mac-1-positive macrophage populations indicated that both of these cell populations could be induced to synthesise nitric oxide by subsequent incubation with 5,6-MeXAA. Incubation of ex vivo spheroids with FAA and 5,6-MeXAA decreased the clonogenicity of EMT6 cells, and this effect was wholly (FAA) or partially (5,6-MeXAA) reversed by the presence of NG-monomethylarginine (250 microM). FAA and 5,6-MeXAA may therefore exert some of their cytotoxic effects on tumour cells through the production of nitric oxide.
黄酮 -8 - 乙酸（FAA）及其更具剂量效力的类似物5,6 - 二甲基呫吨酮 -4 - 乙酸（5,6 - MeXAA）似乎通过血管和其他宿主介导的机制发挥其抗肿瘤作用，并且已知可诱导小鼠巨噬细胞合成一氧化氮。我们研究了一氧化氮在这些药物对宿主细胞浸润的球体的细胞毒性作用中的作用。EMT6小鼠乳腺腺癌细胞在培养物中生长以在体外产生多细胞球体（球体），然后将其腹腔注射到小鼠体内。6天后，将球体取出（离体球体）。与无药物时的0.7 nmol/球体相比，在体外将FAA（890 microM）和5,6 - MeXAA（80 microM）暴露20小时可使亚硝酸盐浓度分别增加至6.7和9.7 nmol/球体。FAA和5,6 - MeXAA在通过腹腔灌洗获得的细胞的体外球体中不会增加亚硝酸盐的产生。然而，用5,6 - MeXAA处理的体外球体和腹膜细胞的混合培养物产生了亚硝酸盐（2.4 nmol/球体），这表明宿主细胞与肿瘤细胞之间的相互作用对于诱导作用很重要。与NG - 单甲基 - L - 精氨酸共同孵育可阻止这些药物对离体球体的作用，表明亚硝酸盐源自L - 精氨酸氧化为一氧化氮。将解离的球体通过细胞分选分为EMT6细胞和Mac - 1阳性巨噬细胞群体，表明这两个细胞群体在随后与5,6 - MeXAA孵育时均可被诱导合成一氧化氮。用FAA和5,6 - MeXAA孵育离体球体可降低EMT6细胞的克隆形成能力，并且这种作用在存在NG - 单甲基精氨酸（250 microM）时完全（FAA）或部分（5,6 - MeXAA）被逆转。因此，FAA和5,6 - MeXAA可能通过一氧化氮的产生对肿瘤细胞发挥其部分细胞毒性作用。
