Simulated microgravity induces programmed cell death in human thyroid carcinoma cells.
The present study focused on the effects of simulated microgravity on the human follicular thyroid carcinoma cell line ML-1. Cultured on a three-dimensional clinostat ML- 1 cells formed three-dimensional multicellular tumor spheroids (MCTS: 0.3 +/= 0.01mm in diameter). Furthermore, ML-1 cells grown on the clinostat showed elevated amounts of the apoptosis-associated Fas protein, of p53 and of bax, but reduced quantities of bcl-2. In addition, signs of apoptosis as assessed by TdT-mediated DUTP digoxigenin nick end labeling, DAPI staining, DNA laddering and 85-kDa apoptosis-related DNA fragments became detectable. The latter ones resulted from enhanced 116-kDa poly(ADP-ribose)polymerase activity. Electron microscopy revealed all morphological signs of apoptosis. Caspase 3 was clearly upregulated. In conclusion, our experiments show that conditions of simulated microgravity induce early programmed cell death and use different pathways of apoptosis.
Kossmehl
Peter
P
Institute of Clinical Pharmacology and Toxicology, Benjamin Franklin Medical Center, Freie Universitat Berlin, Germany. pkossmeh@zedat.fu-berlin.de
Shakibaei
Mehdi
M
Cogoli
Augusto
A
Pickenhahn
Holger
H
Paul
Martin
M
Grimm
Daniela
D