gms | German Medical Science

Objective: During the last decade "stem cell like cells" have been identified in lots of tumor entities. In this context the transcription factors Nanog, Oct4, Sox2, Musashi1 and Klf4 are considered to play an essential role concerning pluripotency (Nanog, Oct4, Sox2) and other stem cell characteristics. In meningiomas there are no robust "stem cell candidates" described up to now. With our study we want to analyse the expression of these possible stem cell markers in meningiomas in order to isolate these cells to establish a suitable in vitro model.

Method: The gene expression of Nanog, Sox2 and Oct4 as specific markers for pluripotency as well as the expression of Klf4, Musashi1, Notch1 and Nestin was quantitatively examined using real-time polymerase chain reaction (qPCR) in 4 meningioma sphere cultures derived from intraoperatively obtained specimens. The data were analyzed by applying the comparative delta-delta Ct method. A primary cell culture of each specimen was examined as well. mRNA from commercial cell line (Ben-Men-1) served as reference.

Results: All tested markers (Nanog, Oct4, Sox2, Musashi1, Klf4, Notch1 and Nestin) were found in meningioma spheres. Compared to primary cultures from the same tissue samples, there was an increased expression of the markers for pluripotency Nanog (9.1 fold; rsph=5.17, rprim=0.56), Oct4 (7.2 fold; rsph=2.75, rprim=0.38) and Sox2 (6.8 fold rsph=2.51, rprim=0.37), but not for Musashi1 (1.09 fold; rsph=2.14, rprim=2.35). In higher passages of the primary cultures, the expression of Musashi1 (until 37.6 fold; rp0=22.20, rp6=0.59) as well as Nanog (6.8 fold; rp0=2.79, rp6=0.42), Oct4 (2.0 fold; rp0=1.24, rp5=0.66) and Sox2 (4.8 fold; rp0=1.30, rp6=0.27) decreased as expected. Notch1 expression did not differ in spheres and primary cell cultures. However, in higher passages (p6) of the primary cell cultures the Notch1 expression rose up to 2 fold.

Conclusions: Markers of pluripotency are overexpressed in meningioma spheres compared to primary cell lines indicating the existence of possible candidates for "stem cell like cells". Our data show that an isolation of these cells from meningeal tissue is possible. However, the impact of these cells on the biological behavior of the tumor still remains an open question.