PKD2 and cholangiocarcinoma: A small number of highly expressed lncRNAs, including lnc-PKD2-2-3, ZEB1-AS1, HOXD-AS1, and LINC00665, have participated in the regulation of CCA stemness (Qiu et al., 2019; Jiang et al., 2020a; Li et al., 2020b; Lu et al., 2021).