Origin and Diversity of Fibroblastic Cells From Intrahepatic Cholangiocarcinoma

Abstract

To elucidate cancer‐associated fibroblast (CAF) origins and diversity within intrahepatic cholangiocarcinoma (ICC), we analyzed the phenotypic, cytogenetic, gene expression profiles, growth properties, and select functions of two novel CAF cell strains (BDEsp‐TDFSM and BDEsp‐TDFDE) along with those of a cholangiocarcinoma (CC) cell strain (BDEsp‐TDECC). Each cell strain was derived from desmoplastic CC formed in rat liver following bile duct inoculation of spontaneously‐transformed rat cholangiocytes. Unlike the CAF strains, BDEsp‐TDECC exhibited anchorage‐independent growth, contained more numerous chromosomal aberrations, and was tumorigenic in rat liver. Both CAF strains exhibited similar, but distinct gene expression profiles compatible with their having a mesenchymal cell origin. TDFSM cells could be distinguished from TDFDE cells by being strongly immunoreactive for α‐smooth muscle actin (SM), positive for the portal fibroblast (PF) marker cofilin 1, negative for the hepatic stellate cell marker desmin (DE), and by producing significantly greater amounts of collagen type I. Co‐culturing BDE‐TDFSM with BDE‐TDECC in a novel 3‐D culture model dramatically potentiated the production of collagen type I and greatly enhanced the numbers of both cytokeratin 19+/Ki‐67+ spheroid/ductal CC structures and TDFSM cells within the matrix when compared with TDECC/TDFDE co‐culture or TDECC, TDFSM, or TDEDE monocultures. The vast majority of CAFs accumulated within the stroma of analyzed rat and human ICC were further found to be SM+/DE‐ , with DE+ fibroblastic cells comprising only a small minority population. Our results suggest that SM+/cofilin1+/DE‐ CAFs promoting desmoplasia and ICC growth may largely be derived from PF.