RFC4 confers radioresistance of esophagus squamous cell carcinoma through regulating DNA damage response

Radioresistance in esophageal squamous cell carcinoma (ESCC) is a critical factor leading to treatment failure and recurrence, yet its underlying molecular mechanisms remain unclear. This study aimed to investigate the role of replication factor C4 (RFC4) in ESCC radioresistance and to explore the underlying mechanisms. We utilized online bioinformatics tools to analyze the properties, functions, and prognostic significance of RFC4 in ESCC. We established cell lines with varying RFC4 expression levels and subjected them to radiation exposure. RFC4 expression was assessed using quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemistry, and immunoblotting. Cell proliferation was evaluated with MTT, 5-ethynyl-2'-deoxyuridine (EdU), and colony formation assays. Apoptosis and cell cycle distribution were analyzed by flow cytometry. Western blotting and immunofluorescence were used to study the impact of RFC4 on the DNA damage response in ESCC cells. A xenograft mouse model was employed to assess tumor growth in vivo. RFC4 expression was significantly upregulated in ESCC tissues and cells, particularly in radioresistant cases. Functional experiments revealed that RFC4 promotes cell proliferation, inhibits apoptosis, induces cell cycle arrest, and mitigates radiation-induced DNA damage responses. Mechanistically, RFC4-mediated radioresistance in ESCC may involve the inactivation of the p53 signaling pathway. In animal studies, RFC4 knockdown, either alone or in combination with radiation therapy, effectively suppressed the growth of xenograft tumors. These findings highlight the potential of targeting RFC4 to overcome radioresistance by modulating the DNA damage response in ESCC, offering promising therapeutic avenues for patients with ESCC.<b>NEW & NOTEWORTHY</b> Our research indicates that replication factor C4 (RFC4) plays a role in conferring radioresistance to esophageal squamous cell carcinoma (ESCC) by bolstering DNA damage repair, primarily through the inhibition of the p53 signaling pathway. This finding positions RFC4 as a promising therapeutic target for combating radioresistance in ESCC, although further research is required to fully comprehend its intricate role in the disease.