CAF-derived exosomal lncRNA FAL1 promotes chemoresistance to oxaliplatin by regulating autophagy in colorectal cancer.

Oxaliplatin is a widely applied anti-cancer drug in clinics for colorectal cancer (CRC) treatment. Nonetheless, the treatment efficacy is always limited by the acquisition of chemoresistance in cancer cells. The deregulation of long non-coding RNA (lncRNA) FAL1 has been implicated in the tumorigenesis and progression of different malignancies. Nevertheless, the possible contribution of lnc-FAL1 in drug resistance development of CRC has not been investigated. Here, we reported the overexpression of lnc-FAL1 in CRC samples, and elevated lnc-FAL1 levels seemed to be associated with the poor survival in CRC patients. We further demonstrated that lnc-FAL1 promoted oxaliplatin chemoresistance in both cell and animal model. Additionally, lnc-FAL1 was mainly derived from exosomes secreted by cancer associated fibroblasts (CAFs), and lnc-FAL1-containing exosomes or lnc-FAL1 overexpression significantly inhibited oxaliplatin-induced autophagy in CRC cells. Mechanistically, lnc-FAL1 acted as a scaffold for the interaction between Beclin1 and TRIM3 to promote TRIM3-dependent Beclin1 polyubiquitination and degradation, thereby suppressing oxaliplatin-induced autophagic cell death. In summary, these data imply a molecular mechanism through which CAF-derived exosomal lnc-FAL1 contributes to the acquisition of oxaliplatin resistance in CRC.