339. CYTOPLASMIC TRANSLOCATION OF BCLAF1 REGULATES SIX1 MRNA STABILITY THROUGH YTHDF2 TO PROMOTE AEROBIC GLYCOLYSIS IN ESOPHAGEAL SQUAMOUS CELL CARCINOMA

Abstract

Abstract Background Esophageal cancer is highly prevalent in China, with esophageal squamous cell carcinoma (ESCC) being the predominant pathological type. However, the unclear pathogenesis of ESCC presents a challenge for identifying effective targets for molecular targeted therapy. RNA methylation is an important epigenetic regulatory mechanism that may play a key role in carcinogenesis. Our research has identified BCLAF1 as an oncogene in ESCC and contributes to cancer progression through an m6A-dependent mechanism. Methods Paraffin specimens and immunohistochemistry (IHC) were used to analyze the correlation between BCLAF1 and ESCC patient prognosis. Edu proliferation, clone formation, scratch, transwell, flow cytometry, and Seahorse assays were conducted to investigate the impact of BCLAF1 on ESCC cells. Subcutaneous xenograft tumor and lung metastasis models in nude mice were performed to assess the role of BCLAF1 in vivo. Immunofluorescence (IF), mass spectrometry, and co-immunoprecipitation analyses were utilized to study the binding relationship between YTHDF2 and BCLAF1. MeRIP-seq, RIP-seq, and RNA-seq analyses determined the RNA profile bound by YTHDF2. Rescue experiments were employed to examine the BCLAF1/YTHDF2/SIX1 axis. Results IHC and IF assays confirmed that BCLAF1 is mainly located in the cytoplasm of ESCC tissues and cells. BCLAF1 is associated with poor prognosis of ESCC patients and also promote malignant progression of ESCC in vitro and in vivo. Mechanistic studies have revealed that BCLAF1 can interact with the m6A reader protein YTHDF2 without affecting its stability, and could affect the binding capacity of YTHDF2 to downstream target SIX1 mRNA in an m6A-dependent manner. Knockdown of YTHDF2 can upregulate the level of SIX1 mRNA and promote aerobic glycolysis in ESCC, which could be rescued by the overexpression of BCLAF1. Conclusion BCLAF1 is a potent oncogene, and its encoded protein undergoes non-classical cytoplasmic translocation in ESCC. Cytoplasmic BCLAF1 directly interacts with YTHDF2 to regulate its function as a reader protein that recognizes and binds m6A sites, enhancing the stability of downstream targets such as SIX1 mRNA, activating the aerobic glycolysis pathway, and ultimately leading to malignant progression of ESCC.