Abstract PO3-25-01: CTLA4 expression profiles and their association with clinical outcomes of breast cancer

Abstract

Abstract The cytotoxic T-lymphocyte-associated protein 4 (CTLA4) is involved in the progression of various cancers, but its biological roles in breast cancer (BRCA) remain unclear. Therefore, we performed a systematic multiomic analysis to expound on the prognostic value and underlying mechanism of CTLA4 in BRCA. First, the expression of CTLA4 in pan-cancer was evaluated using the platforms of Oncomine. Afterward, the web-based bioinformatics platforms of GEPIA and UCLAN were used to compare the expression of CTLA4 in breast cancer and normal tissues. Next, we assessed the relationship between CTLA4 mRNA expression and prognosis in breast cancer patients using the PrognoScan Database, Kaplan-Meier Plotter, and R2: Kaplan-Meier Scanner. Additionally, the correlation between CTLA4 expression and immune cell infiltration in breast cancer and functional enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways was performed to elucidate the potential biological functions of CTLA4. Finally, we used the STRINGdb and cytoHubba plugin Cytoscape to create a PPI network and identify known and predicted structural essentials for CTLA4 functions and the top five hub genes. CTLA4 was highly expressed in BRCA tumor tissue compared to normal tissue (p< 0.01). The CTLA4 mRNA levels in BRCA based on breast cancer subtypes of luminal, Human epidermal growth factor receptor 2 (HER-2), and Triple-negative breast cancer (TNBC) were considerably higher than in normal tissues (p< 0.001). However, the overexpression of CTLA4 was associated with a better prognosis in BRCA (P< 0.001), and was correlated with clinicopathological characteristics including age, T-stage, estrogen receptors (ER), progesterone receptors (PR), and PAM50 (P< 0.01). The infiltration of multiple immune cells was associated with increased CTLA4 expression in BRCA (P< 0.001). CTLA4 was highly enriched in antigen binding, immunoglobulin complexes, lymphocyte-mediated immunity, and cytokine-cytokine receptor interaction. This study provides suggestive evidence of the prognostic role of CTLA4 in breast cancer, which may be a therapeutic target for breast cancer. Furthermore, CTLA4 may influence breast cancer prognosis through antigen binding, immunoglobulin complexes, lymphocyte-mediated immunity, and cytokine-cytokine receptor interaction. These findings help us understand how CTLA4 plays a role in breast cancer and set the stage for more research. Citation Format: Woo Chul Noh, Young Bum Yoo, Kyoung Sik Park, Sang Eun Nam, Seung Hwan Lim. CTLA4 expression profiles and their association with clinical outcomes of breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-25-01.