Epithelial and Mesenchymal Features of Pancreatic Ductal Adenocarcinoma Cell Lines in Two- and Three-Dimensional Cultures

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is an intractable cancer that is difficult to diagnose early, and there is no cure other than surgery. PDAC is classified as an adenocarcinoma that has limited effective anticancer drug and molecular-targeted therapies compared to adenocarcinoma found in other organs. A large number of cancer cell lines have been established from patients with PDAC that have different genetic abnormalities, including four driver genes; however, little is known about the differences in biological behaviors among these cell lines. Recent studies have shown that PDAC cell lines can be divided into epithelial and mesenchymal cell lines. In 3D cultures, morphological and functional differences between epithelial and mesenchymal PDAC cell lines were observed as well as the drug effects of different anticancer drugs. These effects included gemcitabine causing an increased growth inhibition of epithelial PDAC cells, while nab-paclitaxel caused greater mesenchymal PDAC cell inhibition. Thus, examining the characteristics of epithelial or mesenchymal PDAC cells with stromal cells using a 3D co-culture may lead to the development of new anticancer drugs.

Keywords: cell line; pancreatic cancer; pancreatic ductal adenocarcinoma; three-dimensional culture; two-dimensional culture.

Figure 1

Pancreatic cancer cell lines listed in the Cellosaurus.

Figure 2

Phase-contrast and scanning electron microscopic images of PDAC cell lines grown in 2D culture conditions.

Figure 3

Morphology and epithelial or mesenchymal features of PDAC cell lines grown in 3D culture. PK-1 cells that have epithelial features formed small, firm spheres with slightly larger cancer cells that adhered to each other at the surface of the spheres (A–C) [16,37]. In contrast, MIA PaCa-2 cells with mesenchymal features formed large and loose spheres without fusion of the cancer cells (E–G) [16]. The PK-1 spheres were strongly positive for E-cadherin and negative for vimentin by immunostaining (D), while MIA PaCa-2 showed the opposite staining pattern for these markers (H). PK-1 and MIA PaCa-2 cells were cultured in low attachment plates with 10% fetal bovine serum containing RPMI1640 medium for 7 days. Left panels (A,E): phase-contrast images; middle panels (B,C,F,G): scanning electron microscopy with reflected electrons; right panels (D,H): immunocytochemical analyses using cell blocks of spheres. (Supplementary Materials and Methods).