Identification of cancer-associated fibroblasts and analysis of the association of origin with endothelial-to-mesenchymal transition in hepatocellular carcinoma

Background and objective: Cancer-associated fibroblasts (CAFs) promote hepatocellular carcinoma (HCC) progression. Identifying their cellular origin and molecular determinants may help to inform molecular targeted therapy for HCC. Identifying the tissue distribution of CAFs in HCC to indirectly reflect their cellular origin may provide a histological basis for further exploration of their cellular origin and molecular determinants.Methods and results: The tissue distribution of CAFs in 57 HCC tissues was determined by immunohistochemical staining of α-SMA, and α-SMA-positive CAFs were found to be widely located along the capillary network. Immunofluorescent double staining was used to examine the co-expression of CD31 in α-SMA-positive CAFs to identify whether the endothelial-to-mesenchymal transition (EndoMT) is involved in the origin, and obvious colocalization was observed. Visium and Visium HD spatial transcriptomics further revealed endothelial cells (ECs) exhibited remarkable co-expression of CAF-specific marker genes and revealed inferred developmental trajectories to CAFs; molecular determinants, including TIMP1, IGFBP7, THBS2, CD74, COL4A1, COL4A2, AEBP1, S100A6, KCTD12, CALD1, IGHG1, SERPINE1, MCL1, MGP, GSTP1, TAGLN, THBS1, and CTGF, were positively correlated with the spatial developmental trajectories of ECs to CAFs; and CTGF exhibited extensive interactions with other common positively correlated molecular determinants and was a highly connected node in the interaction network.Conclusion: ECs that undergo EndoMT may be one of the potential cellular and mechanical origins of CAFs in HCC, and the development of EndoMT may be associated with CTGF.