3061 - HAT1 Functions as a Lactyltransferase and Mediates RPA1 Lactylation to Promote DNA Repair and Radioresistance in Lung Adenocarcinoma
Presenter(s)
J. He1,2, T. Lai1, W. Zhou1, and Y. Wu1; 1Radiation Oncology Center, Chongqing University Cancer Hospital, Chongqing, China, 2School of Medicine, Chongqing University, Chongqing, China
Purpose/Objective(s): Lysine lactylation (Kla) is a post-translational modification induced by lactate that was discovered in recent years. The mediators and downstream targets of Kla remain unclear. Despite recent advances in understanding the role of Kla in DNA repair, its functions in radioresistance and potential targeted strategies for radiosensitization remain poorly understood. This study aimed to investigate the mediators of Kla involved in radioresistance, in order to identify potential therapeutic targets for improving radiosensitivity in lung adenocarcinoma (LUAD).
Materials/Methods: We evaluated the impact of the expression of currently known major lysine acetyltransferases, which may act as potential lysine lactyltransferases, on patient prognosis by conducting hazard ratio analysis using the TCGA LUAD database. Western blot and immunohistochemistry (IHC) staining were employed to assess protein expression and Kla levels in LUAD samples. ?-H2AX immunofluorescence (IF) staining and comet assay were used to assess cellular DNA damage. The colony formation assay and mouse subcutaneous xenograft model were used to detect radiosensitivity in vitro and in vivo. The DR-GFP reporter assay, RPA1 and RAD51 IF staining were used to detect homologous recombination (HR) repair efficiency. Potential downstream factors were explored through global lactylome and co-immunoprecipitation assays.
Results: The hazard ratio analysis revealed that, among these acetyltransferases, elevated expression of HAT1 was significantly correlated with poor patient survival. By evaluating the expression of HAT1 in LUAD patients using GEPIA and CPTAC databases, we found that both the transcription and protein levels of HAT1 were increased in tumor samples compared with normal tissues. Furthermore, western blot and IHC also confirmed elevated expression of HAT1 in LUAD samples compared with normal tissues, and HAT1 expression in LUAD tissues positively correlated with Kla levels. Moreover, HAT1 knockout significantly reduced Kla levels globally. ?-H2AX IF staining and comet assay showed that HAT1 knockout impaired the DNA damage repair of LUAD cells. Colony formation assay and mouse model suggested that HAT1 knockout or inhibition using a specific inhibitor enhanced radiosensitivity in LUAD cells. The DR-GFP reporter, along with RPA1 and RAD51 IF staining, revealed that HAT1 knockout impaired HR efficiency. Global lactylome and co-immunoprecipitation assay indicated that HAT1 may promote HR by facilitating RPA1 lactylation and leading to radioresistance.
Conclusion: In summary, our results suggest that HAT1-regulated Kla plays a critical role in HR and radioresistance in LUAD cells. Inhibition of HAT1 expression reduced Kla levels and attenuated DNA repair in LUAD cells, thereby increasing radiotherapy sensitivity. Targeting HAT1 may represent a potential therapeutic strategy for reversing the radioresistance caused by lactate accumulation in cancer cells.