Single-cell transcriptomic analysis suggests two molecularly subtypes of intrahepatic cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (iCCA) is a highly heterogeneous cancer with limited understanding of its classification and tumor microenvironment. Here, by performing single-cell RNA sequencing on 144,878 cells from 14 pairs of iCCA tumors and non-tumor liver tissues, we find that S100P and SPP1 are two markers for iCCA perihilar large duct type (iCCA phl ) and peripheral small duct type (iCCA pps ). S100P + SPP1- iCCA phl has significantly reduced levels of infiltrating CD4 + T cells, CD56 + NK cells, and increased CCL18 + macrophages and PD1 + CD8 + T cells compared to S100P-SPP1 + iCCA pps . The transcription factor CREB3L1 is identified to regulate the S100P expression and promote tumor cell invasion. S100P-SPP1 + iCCA pps has significantly more SPP1 + macrophage infiltration, less aggressiveness and better survival than S100P + SPP1- iCCA phl . Moreover, S100P-SPP1 + iCCA pps harbors tumor cells at different status of differentiation, such as ALB + hepatocyte differentiation and ID3+ stemness. Our study extends the understanding of the diversity of tumor cells in iCCA.