Pancreatic cancer spheres are more than just aggregates of stem marker-positive cells

Abstract

SynopsisPancreatic cancer stem-like cells are described by membrane expression of CD24, CD44 and ESA (epithelial-specific antigen) and their capacity to grow as spheres in a serum-free medium containing well-defined growth factors. The capacity of a panel of four pancreatic cancer cell lines (PANC-1, CFPAC-1, PancTu-1 and PSN-1) to form spheres was tested. All cell lines with the exception of PancTu-1 developed spheres. Phenotypically, the sphere-growing cells showed an increased in vitro invasion capability. Both gene and protein expressions of markers of metastases [CXCR4 (CXC chemokine receptor 4), OPN (osteopontin) and CD44v6] and components of active hedgehog pathway signalling were assessed. Spheres clearly demonstrated increased expression of the above-mentioned markers when compared with their adherent counterpart. With the aim of identifying a minimum set of markers able to separate cells that have the capacity to form spheres from those incapable of forming spheres, a PCA (principal component analysis) of the multidimensional dataset was performed. Although PCA of the 'accepted' stemness genes was unable to separate sphere-forming from sphere-incapable cell lines, the addition of the 'aggressiveness' marker CD44v6 allowed a clear differentiation. Moreover, inoculation of the spheres and the adherent cells in vivo confirmed the superior aggressiveness (proliferation and metastasis) of the spheres over the adherent cells. In conclusion, the present study suggests that the sphere-growing cell population is not only composed of cells displaying classical stem membrane markers but also needs CD44v6-positive cells to successfully form spheres. Our results also emphasize the potential therapeutic importance of pathways such as CXCR4 and hedgehog for pancreatic cancer treatment.

Bulk pancreatic cancer cells can convert into cancer stem cells(CSCs) in vitro and 2 compounds can target these CSCs

“…In study of Gavirhi et al, Panc1 cells also aggregated to form spheres in serum-free DMEM/F-12 containing B27, fungizone, heparin, EGF and FGF, and the sphere cells showed stem cell functionalities. 8 This result is similar to ours. How the pancreatic cancer cells acquired CSC characteristics in the serum-free DMEM/F-12 medium containing EGF, bFGF, B27 and insulin?…”

“…7 Gavirhi et al showed that Panc1 cells aggregated to form spheres in serum-free Dulbecco's modified Eagle medium/ Nutrient Mixture F-12(DMEM/F-12) containing B27, fungizone, heparin, fibroblast growth factor(FGF) and epidermal growth factor(EGF), and the sphere cells showed increased tumor-initiating ability and aggressiveness, which are CSC characteristics. 8 Although the characteristics of CSCs have been studied extensively in recent years, there is still some debate about the CSC hypothesis and the origin of CSCs is still uncertain. Tumor heterogeneity has been explained by 2 different models.…”

Estradiol Promotes Breast Cancer Cell Migration via Recruitment and Activation of Neutrophils

“…3D models such as tumor spheres or microtissue more closely mimic the tumor microenvironment than do monolayers of cancer cells. Previous groups have attempted diverse paraffinembedding techniques with several disadvantages, including difficulties in obtaining accurate sections of spheres due to agarose/clot embedding (47)(48)(49). When agarose/clot embedding of mammospheres is performed, mammospheres do not stay in a single plane but sink to different deep layers.…”

Lung-Residing Metastatic and Dormant Neuroblastoma Cells

“…26 In pancreatic and colon cancer a high expression level of CD24 and CD44 characterizes cancer stem cells. [27][28][29] Figure 6 shows that the expression of CD24 and CD133 was significantly higher (P Ͻ 0.05), in DisNB than in the MetNB variants, whereas the c-kit expression was significantly lower (P Ͻ 0.01) in DisNB than in the MetNB variants. Both DisNB and MetNB cells did not express CD34 or CD44.…”