Electron microscopic analysis of different cell types in human pancreatic cancer spheres

Abstract

Abstract. Cancer stem cells (CSCs), which are pluripotent and self-renewable, contribute to the initiation and metastasis of cancer, and are responsible for resistance to chemotherapy and radiation. Pancreatic ductal adenocarcinoma (PDAC) is an aggressive type of cancer that is associated with a high incidence of distant metastasis and recurrence. Sphere formation reveals cell proliferation under nonadherent conditions and is commonly used to identify CSCs; measurements of the number, area and volume of the spheres are used to estimate stemness of PDAC cells. However, detailed morphological analysis of such spheres has not been performed. The aim of the present study was to examine the morphology of spheres isolated from PANC-1 human pancreatic cancer cells via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). PANC-1 cells formed round to irregular oblong spheres within 1 week following seeding in ultra-low-attachment plates. These spheres exhibited higher levels of expression of CSC markers, including nestin, sex determining region Y-box 2, and CD44 containing variant exon 9, compared with adherent cells. SEM analysis revealed that the spheres exhibited a grape-like appearance, harboring cancer cells with smooth or rough surfaces. Similarly, TEM analysis detected cancer cells with varying surface types within the spheres: Those with smooth surfaces, irregular large protrusions, protrusions and a small number of microvilli, and those with many microvilli throughout the entire cell surface. These morphological differences among cancer cells may be indicative of different stages in the differentiation process, from CSCs to non-CSCs, within the spheres.

Stemness and anti‐cancer drug resistance in ATP‐binding cassette subfamily G member 2 highly expressed pancreatic cancer is induced in 3D culture conditions

“…In PDAC cells, ABCG2 expression was suggested to be correlated with malignant CSC phenotypes . In our recent study using low‐vacuum scanning and transmission electron microscopy, we found that the spheres of PANC‐1 cells contain a different type of cell that displayed a smooth cell surface or microvilli formation on the cell surface in low‐attachment plates . Normal pancreatic ductal cells have microvilli, suggesting that PANC‐1 cells with microvilli are a mature type of cell.…”

FGFR4 Inhibitor BLU9931 Attenuates Pancreatic Cancer Cell Proliferation and Invasion While Inducing Senescence: Evidence for Senolytic Therapy Potential in Pancreatic Cancer

“…Thus, autocrine/paracrine FGF19/FGFR4 signaling is not involved in regulating the expression of anticancer drug transporters and the resistance toward anticancer drugs in PDAC cells. Next, we examined sphere-forming ability, which is viewed as an indicator of self-renewal and stemness [ 43 , 44 , 45 ]. Sphere-forming assays showed that the number of spheres was not different between control and 2 μM BLU9931-treated PK-1 cells ( Figure 4 D).…”

“…Our findings suggest that FGF19/FGFR4 signaling had little association with stemness in PDAC cells ( Figure 4 ). Thus, FGFR4 and FGF19 expression was reduced in 3-D culture ( Figure 4 E), which is an optimal culture condition for CSCs [ 43 , 44 , 45 ], suggesting that FGF19/FGFR4 activation was not contributing to CSC formation. FGFR1 and FGFR4 are known to compete via their interactions with KLB [ 58 ].…”

Scalable biofabrication and morphology evaluation of tissue spheroids

“…К первой группе методов можно отнести фазово-контрастную микроскопию и количественную оценку жизнеспособности клеток в сфероидах. Ко второй группе относятся конфокальная и двухфотонная микроскопия, сканирующая и трансмиссионная [3], [7], [16], [17], [21] электронная микроскопия, гистохимические и иммуногистохимические исследования.…”

“…К недостаткам можно отнести относительно высокую стоимость и специфическую пробоподготовку. Кроме того, сканирующая электронная микроскопия без дополнительной обработки образцов дает информацию только о структурных свойствах поверхности без оценки внутреннего строения сфероида [21,22].…”