Jianpi Jiedu Recipe inhibits colorectal cancer liver metastasis via regulating ITGBL1-rich extracellular vesicles mediated activation of cancer-associated fibroblasts.

BACKGROUND:Extracellular vesicles (EVs) contribute greatly to the formation of pre-metastatic niche and tumor metastasis. Our previous study has revealed that tumor-derived ITGBL1 (integrin beta- like 1)-rich EVs activate fibroblasts through the NF-κB signaling to promote colorectal cancer (CRC) metastasis. Targeting ITGBL1-loaded EVs may be a new and effective therapy for treating CRC metastasis. Simultaneously, our preliminary clinical trial has demonstrated that Jianpi Jiedu Recipe (JPJDR) was an ideal alternative traditional Chinese medicine for the prevention and treatment of CRC metastasis. However, the underlying mechanism of JPJDR in the prevention of CRC metastasis is not clear. In this study, we will investigate the regulatory effect of JPJDR on ITGBL1 levels in CRC-derived EVs, and to detect how JPJDR regulate ITGBL1-rich EVs mediated activation of fibroblasts to inhibit CRC metastasis. METHODS:EVs derived from CRC cells with/without JPJDR treatment were obtained by ultracentrifugation, following by characterization with electron microscopy, LM10 nanoparticle characterization system and western blot. The migration and growth of CRC cells were tested by transwell assay, wound healing assay and colony formation assay. The effect of JPJDR on the fibroblasts-activation associated inflammatory factors including IL-6, IL-8 and α-SMA was detected by real-time PCR. The levels of IL-6, IL-8 and α-SMA in the cell culture supernatant were detected by ELISA. The protein expressions of TNFAIP3, ITGBL1, p-NF-κB, IκBα and β-actin were detected by western blot. Liver metastasis model in mice was established by injecting MC38 single cell suspension into the spleen of mice to observe the effect of JPJDR on CRC liver metastasis. Immunohistochemistry were applied to detect the expression of ITGBL1 and TNFAIP3 in the liver metastatic tissues. Tissue immunofluorescence detection was performed to observe the regulatory effect of JPJDR on the ITGBL1-NF-κB signaling pathway. Cancer-associated fibroblasts (CAFs) in the liver metastatic tissues were sorted and characterized by platelet-derived growth factor receptor β (PDGFRβ) with flow cytometry, following by the detection of inflammatory factors including IL-6, IL-8 and α-SMA using real-time PCR. RESULTS:JPJDR reduced the ITGBL1 levels in CRC cells-derived EVs. JPJDR inhibited the migration and growth of CRC cells via regulating ITGBL1-rich EVs mediated fibroblasts activity. Mechanically, JPJDR decreased fibroblasts activation by regulating ITGBL1-rich EVs mediated TNFAIP3-NF-κB signaling. Further in vivo experiments demonstrated that JPJDR reduced CRC liver metastasis by regulating ITGBL1-rich EVs secretion from CRC and blocked the fibroblasts activation by regulating ITGBL1-TNFAIP3- NF-κB signaling. CONCLUSION:Our research demonstrated that JPJDR preventd CRC liver metastasis via down-regulating CRC-derived ITGBL1-loaded EVs mediated activation of CAFs, providing the experimental evidence for the clinical application of JPJDR in the prevention and treatment of CRC metastasis. More importantly, our study confirmed the great benefits of therapeutic targeting the EVs-mediated metastasis and warranted future clinical validation.