Abstract P3-05-24: Correlation between the expression of JCAD in plasma exosomes and breast cancer
Authors: Liu Douwaner , Chi Yayun , Xiu Bingqiu , Zhang Qi , Chi Wei-Ru , Zhang Liyi , Xiong Min , Wu Jiong 
Published: March 2023

Abstract
Background: Breast cancer is the most common cancer in women. The five-year survival rate of patients with stage 0 and stage I breast cancer is more than 95%, that of patients with stage II breast cancer is 80%, that of patients with stage III breast cancer is about 50%, and that of stage IV breast cancer is less than 30%. The stage of breast cancer is closely related to the prognosis. Exosomes are membrane vesicles secreted by living cells, which carry donor cell specific genetic information. They can exist stably in the circulatory system, so they are ideal biomarkers. Method: We collected 128 breast cancer patients (17 benign cases, 26 stage I cases, 36 stage II cases, 15 stage III cases and 34 stage IV cases) treated in our center from 2018 to 2019. We collected patients’ plasma and extracted exosomes, then we sent them for sequencing. We analyzed the difference between benign cases’ and stage IV cases’ sequencing results, and then we screen them by comprehensively considering the change trend of gene expression from benign cases to stage IV cases, the survival curve of patients and the lymph node metastasis. The clinicopathological factors and progression free survival (PFS) of breast cancer patients were analyzed by Cox regression. Finally, JCAD was selected. Using virus to stably overexpress JCAD and shRNA technology to knock down JCAD, the function of JCAD for the proliferation and metastasis of breast cancer was discussed through CCK8 cell proliferation experiment, EdU cell proliferation experiment, plate cloning experiment, transwell cell migration experiment. T-test and chi square test were performed on the data. P &lt; 0.05 showed that the difference was statistically significant. Kaplan-Meier survival was used to analyze the long-term efficacy. Result 1. The expression of JCAD mRNA in exosomes increased from benign to stage 4 (P &lt; 0.001). In addition, patients with lymph node metastasis had significantly higher expression of exosome JCAD (p=0.009), and the prognosis of patients with high expression of exosome JCAD was poor (p=0.003). This conclusion has also been verified in TCGA database. Finally, Cox regression analysis showed that JCAD was an independent prognostic factor affecting PFS (p=0.005). 2. JCAD is transmitted between cells in the form of exosomes: In breast cancer cells, stable transgenic strains with overexpression of JCAD and shRNA knockdown strains of JCAD were constructed. The exosomes were extracted by ultracentrifugation for RNA and protein level verification. It shows that there was a difference in the expression of JCAD in the exosomes of overexpression and knockdown strains. After adding exosome inhibitor GW4869 to culture cells, it was found that the level of JCAD mRNA secreted by exosomes decreased significantly. In addition, through PKH26 exosome fluorescence labeling method, it was found that JCAD was transmitted between cells in the form of exosomes. 3. JCAD can promote the proliferation and migration of breast cancer cells: This experiment verified the ability of JCAD to promote the proliferation of breast cancer cells through CCK8 cell proliferation experiment, EdU cell proliferation experiment, plate cloning experiment. Then the ability of JCAD to promote the migration of breast cancer cells was verified by transwell cell migration experiment. The exosomes were added to wild type cells for co-culture. It was further found that the exosomes with high expression of JCAD could promote the proliferation and migration of breast cancer cells. Conclusion JCAD is significantly overexpressed in stage IV patients and patients with lymph node metastasis. Moreover, JCAD is an independent prognostic factor affecting PFS, and the exosome JCAD is expected to become a potential prognostic liquid biopsy marker. Further cell experiments showed that JCAD can be transmitted between breast cancer cells through exosomes and promote the proliferation and metastasis of breast cancer cells.
Citation Format: Douwaner Liu, Yayun Chi, Bingqiu Xiu, Qi Zhang, Wei-Ru Chi, Liyi Zhang, Min Xiong, Jiong Wu. Correlation between the expression of JCAD in plasma exosomes and breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-24.