Tumor-derived CXCL5 promotes 5-fluorouracil resistance in colorectal cancer cells via p21 downregulation.

The efficacy of 5-fluorouracil treatment for colorectal cancer (CRC) is substantially compromised by drug resistance, although the underlying mechanisms remain unclear. In this research, we aimed to explore the role and mechanism of action of CXC motif chemokine ligand 5 (CXCL5) in 5-fluorouracil resistance. RNA sequencing was conducted to detect abnormally expressed genes in the 5-fluorouracil-resistant colon cancer cell line, HCT8-5FU. CXCL5 expression in CRC tissues and cell lines was evaluated using RT-qPCR, western blotting, and immunohistochemistry. In vivo and in vitro assays were conducted to evaluate the role of CXCL5 in the promotion of CRC progression. Mass spectrometry and co-immunoprecipitation were employed to investigate the role of CXCL5 in CRC development and 5-fluorouracil resistance. Immunofluorescence and western blot analyses were employed to determine the subcellular localization of CXCL5 and its associated signaling pathways. CXCL5 expression was elevated in both CRC tissues and cell lines. CXCL5 promoted CRC cell growth and resistance to 5-fluorouracil in both in vitro and in vivo settings. Mechanistically, CXCL5 may modulate the MDM2/p53 axis to inhibit p21 by binding to RALY. In this study, CXCL5 accelerated CRC progression and increased CRC cell resistance to 5-fluorouracil via the inhibition of p21 expression. Thus, CXCL5 is a potential target for CRC therapeutic strategies.