Fig. 6
HSCs activated by MIR181A1HG in CRC cell-derived EVs promote CRLM by secreting CXCL12 to induce premetastatic niche formation through recruiting MDSCs and remodeling the ECM in the liver. (a) LX2 cells were first activated by coculturing with RKO CRC cells, which were first transfected with MIR181A1HG-knockdown or control constructs. A human chemokine screening test kit was subsequently used to identify differentially expressed chemokines in LX2 cells. (b) ELISAs were used to assess the effect of exogenous MIR181A1HG on the expression of CXCL12 in LX2 cells. LX2 cells were first activated by coculturing with EVs derived from HT29 and RKO cells, which had been pretransfected with MIR181A1HG-overexpressing or MIR181A1HG-knockdown constructs. (c) The expression of CXCL12 in LX2 cells was determined by ELISA. The luciferase-labeled CRC cell line HCT8 was then injected into the spleens of nude mice to establish a mouse model of CRLM, and conditioned medium (CM) was injected into the tail vein. The impact of CXCL12 secreted by activated HSCs on CRLM in vivo was determined via spleen injection to construct mouse models of CRLM. (d) Representative live images of LMs in nude mice. (e) Number of metastatic colonies in the livers of the nude mice from different groups determined by live imaging and HE staining. (f) Overall survival of each group of mice (n = 10 for each group). (g) The expression levels of Ly6G+, α-SMA and fibronectin in the LM tissues of each group were assessed by western blotting. (h) Quantification of MDSCs in each group of mice. (i) Schematic model showing that the lncRNA MIR181A1HG in EVs derived from highly metastatic CRC cells functions as a ceRNA by sponging miR373-3p to activate HSCs via the TGFβRII/Smad2/3 signaling pathway in CRLM. (nsP>0.05, *P < 0.05, **P < 0.01, ***P < 0.001)