Department of Animal Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, Punjab, India.
Department of Biochemistry and Microbial Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, Punjab, 151 001, India.
Mol Cell Biochem. 2019 Jan;450(1-2):135-147. doi: 10.1007/s11010-018-3380-2. Epub 2018 Jun 25.
The immune responses, involved in recognition of cancer-specific antigens, are of particular interest as this may provide major leads towards developing new vaccines and antibody therapies against cancer. An effective treatment for cancer is still a challenge because there are many mechanisms through which the tumor cells can escape the host immune surveillance. Oxidative stress or respiratory burst which is host's mechanism to kill the foreign particles is used as defense mechanism by the tumor cells. The tumor cells uses this oxidative stress to form neo-antigens which in turn makes them undetectable and can escape the host immune surveillance. The human lung carcinoma (A549) cells were treated using 100 µM HO to induce oxidative stress, and the extent oxidative modifications were detected at the level of membrane and proteins in form of lipid peroxidation and protein carbonyls respectively. Nitric oxide and iNOS levels were estimated by Griess assay and immunostaining, respectively. The oxidized tumor proteins were visualized on one-dimensional SDS-PAGE. The HO-treated (15 min and 24 h post-treatment) A549 cells were co-cultured with THP-1 cells to subsequently visualize the phagocytic activity by Giemsa and CFSE staining to understand the role of neo (oxidized) tumor antigens in eliciting alteration in immune responses. A significant decline in the percent engulfed cells and decrease in the levels of reactive oxygen species was observed. Immunohistostaining for p47, which is an important indicator of the oxygen-dependent phagocytosis, showed a decrease in its levels when cells were treated for only 15 min with 100 µM HO, whereas at 24-h post-treatment there was no change in the p47 levels. The study has established oxidative stress as a new pathogenic mechanism of carcinogenesis and will open new avenues for clinical intervention, adjunct therapies for cancer, and its control at the initial stage by targeting these neo-antigens.
免疫反应涉及对癌症特异性抗原的识别，这是特别有趣的，因为这可能为开发新的癌症疫苗和抗体疗法提供主要线索。癌症的有效治疗仍然是一个挑战，因为肿瘤细胞有许多机制可以逃避宿主的免疫监视。氧化应激或呼吸爆发是宿主杀死外来颗粒的机制，被肿瘤细胞用作防御机制。肿瘤细胞利用这种氧化应激形成新抗原，从而使它们无法被检测到，并可以逃避宿主的免疫监视。用人肺癌（A549）细胞用 100µM HO 处理诱导氧化应激，分别以脂质过氧化和蛋白质羰基的形式在膜和蛋白质水平上检测氧化修饰的程度。通过格里斯测定法和免疫染色分别估计一氧化氮和 iNOS 水平。在一维 SDS-PAGE 上可视化氧化的肿瘤蛋白。用 HO 处理（处理后 15 分钟和 24 小时）的 A549 细胞与 THP-1 细胞共培养，随后通过吉姆萨染色和 CFSE 染色观察吞噬活性，以了解新（氧化）肿瘤抗原在引发免疫反应改变中的作用。吞噬细胞的百分比明显下降，活性氧水平下降。用 100µM HO 处理仅 15 分钟后，p47 的免疫组化染色（氧依赖性吞噬作用的重要指标）显示其水平下降，而在处理后 24 小时，p47 水平没有变化。该研究确立了氧化应激作为致癌作用的新发病机制，并将为临床干预、癌症辅助治疗以及通过靶向这些新抗原在早期控制癌症开辟新途径。
