Cui Feng, Qu Di, Sun Ruya, Zhang Mingming, Nan Kejun
Department of Oncology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China.
Department of Oncology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shannxi 710061, P.R. China.
Exp Ther Med. 2020 Feb;19(2):1400-1406. doi: 10.3892/etm.2019.8343. Epub 2019 Dec 18.
Globally, colorectal cancer (CC) is the third leading cause of mortality associated with cancer. Natural killer (NK) cells are a major class of cells that are responsible for eliminating tumor cells and cytokine production. NK cell-mediated production of interferon gamma (IFN-γ) has antiviral, immunoregulatory and anti-tumor properties. IL-15 is important in linking inflammation with cancer. For instance, IL-15 promotes humoral and cell-mediated immune responses to inhibit tumor growth. IL-15 inhibits colitis-associated colon carcinogenesis by inducing antitumor immunity. However, the effect of NK cell-mediated IFN-γ on IL-15 expression in CC progression remains unknown. mRNA and protein level were detected using reverse transcription-quantitative PCR and western blotting, respectively. IFN-γ concentrations were detected using ELISAs. The cytotoxicity of NK-92 cells on SW480 cells was detected using cytoTox 96 non-radioactive cytotoxicity assays. Cell apoptosis and cell proliferation was detected using flow cytometry and CCK-8 assays, respectively. IL-2 was used for NK-92 stimulation, IL-15 antibodies were used to neutralize IL-15 bioactivity. For the present study, 21 patients with CC and 21 healthy volunteers were enrolled at the First Affiliated Hospital of Xi'an Jiaotong University. IL-15 mRNA and protein expression were significantly lower in NK cells isolated from the CC group compared with healthy volunteer group. IL-2 enhanced the production/secretion of IFN-γ in addition to enhancing NK-92 cell-mediated killing of SW480 cells. Compared with the control group, NK-92 cells treated with IL-2 alone significantly increased cell apoptosis, BAX expression levels as well as phosphorylated (p)-Janus kinase 2 and p-STAT1 protein levels, whilst reducing cell viability and Bcl-2 protein levels in SW480 cells. These observations were not made when treated with IL-2 and polyclonal antibody (pAb) targeting IL-15. Taken together, NK cell-mediated IFN-γ served a pivotal role in CC by regulating IL-15. The effects of IL-2 induced IFN-γ were abolished by pAb IL-15 treatment. The mechanisms of action behind how IFN-γ regulates IL-2 is unclear, and is a promising area for future research.
在全球范围内，结直肠癌（CC）是与癌症相关的第三大主要死因。自然杀伤（NK）细胞是一类主要负责清除肿瘤细胞和产生细胞因子的细胞。NK细胞介导的γ干扰素（IFN-γ）产生具有抗病毒、免疫调节和抗肿瘤特性。白细胞介素-15（IL-15）在将炎症与癌症联系起来方面很重要。例如，IL-15促进体液免疫和细胞介导的免疫反应以抑制肿瘤生长。IL-15通过诱导抗肿瘤免疫抑制结肠炎相关的结肠癌发生。然而，NK细胞介导的IFN-γ在CC进展中对IL-15表达的影响仍然未知。分别使用逆转录定量PCR和蛋白质印迹法检测mRNA和蛋白质水平。使用酶联免疫吸附测定法（ELISA）检测IFN-γ浓度。使用细胞毒性96非放射性细胞毒性测定法检测NK-92细胞对SW480细胞的细胞毒性。分别使用流式细胞术和CCK-8测定法检测细胞凋亡和细胞增殖。使用IL-2刺激NK-92细胞，使用IL-15抗体中和IL-15生物活性。在本研究中，西安交通大学第一附属医院招募了21例CC患者和21名健康志愿者。与健康志愿者组相比，从CC组分离的NK细胞中IL-15 mRNA和蛋白质表达显著降低。IL-2除了增强NK-92细胞介导的对SW480细胞的杀伤作用外，还增强了IFN-γ的产生/分泌。与对照组相比，单独用IL-2处理的NK-92细胞显著增加了SW480细胞的凋亡、BAX表达水平以及磷酸化（p）- Janus激酶2和p-STAT1蛋白水平，同时降低了细胞活力和Bcl-2蛋白水平。当用IL-2和靶向IL-15的多克隆抗体（pAb）处理时，未观察到这些现象。综上所述，NK细胞介导的IFN-γ通过调节IL-15在CC中起关键作用。pAb IL-15处理消除了IL-2诱导的IFN-γ的作用。IFN-γ如何调节IL-2背后的作用机制尚不清楚，是未来研究的一个有前景的领域。
