（Original text Download：Anti-PADI4 antibody suppresses breast cancer by repressing the citrullinated fibronectin in the tumor microenvironment）
Recently, Professor changxiaotian's team from the medical research center of the Affiliated Hospital of Qingdao University made a research achievement "Anti-PADI4 antibody suppresses breast cancer by repressing the citrullinated fibronectin in the tumor microenvironment(抗 PADI4 抗体通过抑制肿瘤微环境中的瓜氨酸纤连蛋白来抑制乳腺癌)",Published in ElSEVIER (Biomedicine & Pharmacotherapy) ，Sub-millimeter small animal PET/CT(model: Madiclab PSA094) of MadicLab Molecular Imaging Co.,Ltd. provides important small animal tumor imaging and quantitative analysis in the paper.
1、Abstract of this article
PADI4, an enzyme catalyzing arginine residues to citrulline residues, is highly expressed in malignant tumors. This study prepared a monoclonal anti-human PADI4 antibody and investigated the therapeutic effect of the antibody on breast tumors and the functional mechanism.
After treatment with PADI4 antibody, the changes in tumor-bearing mice were examined by PET-CT,（The mice were anesthetized with isoflurane, and the imaging agent 18F-fluorodeoxyglucose (18F-FDG) was injected into the tail vein of the mice at a dose of 12 MBq per mouse. PET-CT projection scanning (60 KV, 10 mA) was conducted on PET-CT equipment (MadicLab PSA094, Madic Technology, China). The image was reconstructed by three-dimensional order subset expectation maximization (3D-OSEM), and PET-CT fusion was performed on the images using Pmod software. CT images were used to assist PET images in identifying tumor characteristics. The standardized uptake value (SUV) of the tumor tissues was calculated by the following formula: SUV = region of interest activity concentration (MBq/ml)/injection activity concentration (MBq/ml)/body weight (kg).） pathological assays, biochemical tests, routine blood tests, cytokine assays and metabolic assays. We used PADI4 recombinant protein to catalyze fibronectin (Fn) and then used citrullinated fibronectin (Cit-Fn) to culture MDA-MB-231 cells. We also treated Cit-Fn cultured cells with PADI4 antibody. The cultured cells were examined using cell proliferation, apoptosis, colony formation, migration and glycolic ATP production. Citrullination in the tumor tissues and peripheral blood was measured using Western blotting and ELISA, respectively.
Following PADI4 antibody treatment, tumor growth was significantly suppressed, and the number of apoptotic cells in tumor tissues was increased. The citrullination level in peripheral blood and tumor tissues was decreased, EMT-related gene expression in tumors was also decreased, and the spontaneous movement of tumor-bearing mice was increased following treatment. Following antibody treatment, the serum concentrations of IL-10, IL-12p70, IL-23, ALT and AST were significantly decreased. MDA-MB-231 cells treated with Cit-Fn showed increased cell proliferation, cell migration, colony formation and glycolytic ATP production and decreased apoptosis. The growth and migration of MDA-MB-231 cells were reduced following PADI4 antibody treatment, and PADI4 antibody inhibited the citrullination of fibronectin in vitro.
Fig. 1. Tumor growth in tumor-bearing mice. A. Tumor-bearing mice with or without PADI4 antibody treatment. B. Tumor tissues were collected from tumor-bearing mice with or without PADI4 antibody treatment. C. Tumor volume growth curves of the tumor-bearing mice. D. Tumor weight of the tumor-bearing mice. E. PET-CT scanning of the tumor-bearing mice. F. Tumor volume of PET-CT scan. G. The SUV value of the tumor tissues. H. Hematoxylin-eosin staining of tumor tissues from tumor-bearing mice I. TUNEL staining of tumor tissue in tumor-bearing mice (200X).
The PADI4 antibody had a therapeutic effect on breast tumors by inhibiting the citrullination of fibronectin to change the tumor tissue microenvironment. PADI4 antibody is a potential means for tumor treatment.