Enterococcus faecalis Promotes Chemoresistance in Colorectal Cancer via Lactate-Mediated MOB3B Down-Regulation
Authors: QI Jingru, ZHANG Weiyang, YANG Longan, LI Yuxuan, SHI Zhuoran, LIN Chuman, HUANG Yiyan, HUA Xing, ZHOU Rui, YU Lina
AIM: To investigate the role of Enterococcus faecalis (E. faecalis) in colorectal cancer (CRC) chemoresistance and elucidate the underlying molecular mechanisms. METHODS: Conditioned media (CM) were collected from cultures of E. faecalis treated with oxaliplatin or 5-fluorouracil (5-FU). The effects of these media on CRC chemoresistance were evaluated using in vitro functional assays and in vivo xenograft models in nude mice. Bioinformatics analysis was conducted to identify candidate genes associated with E. faecalis-induced chemoresistance. Gain- and loss-of-function experiments were performed to assess the role of MOB3B in regulating CRC cell proliferation and drug sensitivity. RT-qPCR, Western blot, and immunohistochemistry were used to validate the molecular mechanisms involved. Metabolomic profiling identified key metabolites in E. faecalis-oxaliplatin CM, and their roles in drug resistance were also confirmed. RESULTS: Compared with oxaliplatin treatment alone, E. faecalis-oxaliplatin CM significantly promoted CRC cell growth and chemoresistance in vitro (P<0.01). Tumors treated with E. faecalis-oxaliplatin CM exhibited significantly larger volumes and faster growth in vivo (P<0.01). Mechanistically, down-regulation of MOB3B mediated the chemoresistance-promoting effects of E. faecalis-oxaliplatin CM (P<0.01). Overexpression of MOB3B inhibited CRC cell proliferation and enhanced chemosensitivity, whereas MOB3B knockdown produced the opposite effect (P<0.01). Metabolomic analysis revealed elevated lactate levels in the E. faecalis-oxaliplatin CM (P<0.01). Lactate inhibition significantly reduced CRC cell proliferation, reversed chemoresistance, and restored MOB3B expression (P<0.01). CONCLUSION: E. faecalis promotes chemoresistance in CRC through lactate-mediated down-regulation of MOB3B, highlighting MOB3B as a potential therapeutic target for overcoming CRC chemoresistance.