Summary
Only few human meningiomas show a normal karyotype whereas in most of them a G-Chromosome loss is the primary cytogenetic event, often followed by the loss of further, mostly acrocentric, chromosomes. As the karyotype of each meningioma is normally uniform, these tumors seemed to us expecially suitable to investigate which chromosomes are involved in nucleolar organisation. We compared the number of nucleoli in cells of meningioma cultures which have lost none, one, two or more acrocentric chromosomes. Between tumours with normal karyotype and those showing a G monosomy only a slight difference was found. However there was a highly significant decrease in the nucleolar count after the loss of two or more acrocentric chromosomes (p<0.0l). The loss of non-acrocentric chromosomes did not influence the number of nucleoli. Furthermore we observed that meningioma cells being cultured only for 2–3 days, contained less nucleoli than cells of cultures from the 7th to 9th day (p<0.01). Already in this early stage of proliferation a strongly diminished number of nucleoli appeared in tumours having lost more than one acrocentric chromosome. These results prove acrocentric chromosomes play the most important role in nucleolar organisation.
Zusammenfassung
Nur wenige menschliche Meningeome zeigen einen normalen Chromosomensatz, während bei den meisten der Verlust eines G-Chromosoms zu beobachten ist, auf den oft der Verlust weiterer, meist akrozentrischer, Chromosomen folgt. Da der Chromosomensatz in den einzelnen Meningeomen meist einheitlich ist, erscheinen diese Tumoren besonders für die Untersuchung geeignet, welche Chromosomen an der Nucleolusorganisation beteiligt sind. Zu diesem Zweck verglichen wir die Nucleolenzahlen in Meningeomkulturen die kein, ein, zwei oder mehr akrozentrische Chromosomen verloren hatten. Dabei fand sich nur ein geringer Unterschied zwischen Tumoren mit normalem Chromosomensatz und solchen mit einer G-Monosomie. Ein hochsignifikanter Rückgang der Nucleolenzahl war jedoch bei Verlust von 2 oder mehr akrozentrischen Chromosomen zu beobachten (P<0.01). Ein Verlust anderer Chromosomen hatte keinen Einfluß auf die Nucleolenzahl.
Es konnte weiterhin beobachtet werden, daß bei nur 2–3tägiger Züchtungsdauer die Nucleolenzahl in allen untersuchten Meningeomgruppen signifikant niedriger war, als bei einer Kulturdauer von 7–9 Tagen (P<0.01). Bereits in diesem frühen Wachstumsstadium der Meningeomkulturen wurde eine stark verminderte Nucleolenzahl bei den Tumoren festgestellt, die mehrere akrozentrische Chromosomen verloren hatten.
Die Ergebnisse stützen die Annahme, daß die akrozentrischen Chromosomen den entscheidenden Anteil an der Nucleolusorganisation haben.
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This study was supported by the Deutsche Forschungsgemeinschaft (Za 32/9).
We thank Mrs. Jutta Winkler, Miss Helma Büscher and Mr. Werner Kofler for skilful assistance in tissue culture and chromosome preparation.
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Zankl, H., Zang, K.D. The role of acrocentric chromosomes in nucleolar organization. Virchows Arch. Abt. B Zellpath. 11, 251–256 (1972). https://doi.org/10.1007/BF02889403
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DOI: https://doi.org/10.1007/BF02889403