Sun H, Gutierrez P, Jackson M J, Kundu N, Fulton A M
Greenebaum Cancer Center and Department of Pathology, University of Maryland, Baltimore 21201, USA.
J Immunother. 2000 Mar-Apr;23(2):208-14. doi: 10.1097/00002371-200003000-00005.
Several laboratories have reported anti-tumor activity for high levels of interleukin-10 (IL-10) expressed as a transgene or administered as recombinant protein. The authors have reported a positive correlation for nitric oxide production and anti-tumor activity of IL-10 in a murine model of breast cancer. In the current study, they sought evidence of a mechanistic role for nitric oxide in IL-10-mediated tumor growth inhibition. They wanted to determine whether pharmacologic inhibition of nitric oxide synthase (NOS) activity reverses the therapeutic effect of IL-10. Administration of either of two NOS inhibitors, aminoguanidine (AG) or L-lysine,N6-1-iminoethyl-dihydrochloride, appears to abrogate in part the tumor growth inhibition observed when IL-10 is overexpressed as a transgene in two murine mammary tumor cell lines. Nitric oxide levels were assessed at the tumor site by measuring nitrosylated heme levels by electron spin resonance spectroscopy. Nitric oxide hemoglobin levels were lower in tumors from aminoguanidine-treated mice, indicating that effective inhibition of nitric oxide production occurred at the tumor site. Previous investigations showed that the inducible form of NOS protein (iNOS), but not constitutive NOS, was expressed at higher levels in IL-10-expressing tumors. Because iNOS is regulated at the transcriptional level, the authors compared iNOS mRNA levels in IL-10 and control tumors. Northern analysis revealed strong iNOS message expression in all six IL-10-expressing tumors examined, whereas message was faintly detected in parental or 66-neo tumors. The inducible form of NOS is responsive to induction by interferon-gamma (IFN-gamma). The role of IFN-gamma in IL-10-mediated tumor inhibition and iNOS mRNA induction was determined. When tumors were transplanted to IFN-gamma mutant mice, the tumor-inhibitory activity of IL-10 was lost. Furthermore, iNOS mRNA was no longer induced in the absence of host expression of IFN-gamma. These data indicate that nitric oxide contributes to the anti-tumor activity of IL-10 and that expression of iNOS in this context depends on IFN-gamma.
几个实验室报告了高水平表达的白细胞介素-10（IL-10）作为转基因或作为重组蛋白给药时的抗肿瘤活性。作者在乳腺癌小鼠模型中报告了一氧化氮产生与IL-10抗肿瘤活性之间的正相关。在当前研究中，他们寻找一氧化氮在IL-10介导的肿瘤生长抑制中发挥机制作用的证据。他们想确定一氧化氮合酶（NOS）活性的药理抑制是否会逆转IL-10的治疗效果。给予两种NOS抑制剂中的任何一种，氨基胍（AG）或L-赖氨酸，N6-1-亚氨基乙基二盐酸盐，似乎部分消除了在两种小鼠乳腺肿瘤细胞系中将IL-10作为转基因过度表达时观察到的肿瘤生长抑制。通过电子自旋共振光谱法测量亚硝基化血红素水平来评估肿瘤部位的一氧化氮水平。氨基胍处理的小鼠肿瘤中的一氧化氮血红蛋白水平较低，表明在肿瘤部位发生了一氧化氮产生的有效抑制。先前的研究表明，诱导型NOS蛋白（iNOS）而非组成型NOS在表达IL-10的肿瘤中表达水平更高。由于iNOS在转录水平受到调节，作者比较了IL-10肿瘤和对照肿瘤中的iNOS mRNA水平。Northern分析显示，在所检查的所有六个表达IL-10的肿瘤中均有强烈的iNOS信息表达，而在亲本或66-neo肿瘤中仅微弱检测到该信息。诱导型NOS对干扰素-γ（IFN-γ）的诱导有反应。确定了IFN-γ在IL-10介导的肿瘤抑制和iNOS mRNA诱导中的作用。当将肿瘤移植到IFN-γ突变小鼠中时，IL-10的肿瘤抑制活性丧失。此外，在没有宿主IFN-γ表达的情况下，iNOS mRNA不再被诱导。这些数据表明一氧化氮有助于IL-10的抗肿瘤活性，并且在这种情况下iNOS的表达取决于IFN-γ。
