The adaptation of 3T3 cells to simulated microgravity by retrieving the major cell cycle-related protein expression during long-term in vitro proliferation

The present study aimed to assess the effects of simulated microgravity (SMG) on 3T3 cell proliferation and the expression of cell cycle regulators. 3T3 cells were induced to SMG by Gravite® for 8 days, while the control group was treated with 1G condition. The result showed that the SMG condition causes a decrease in proliferative activity in 3T3 cells. In the SMG group, the expression of cell cycle-related proteins was lower than the control on day 3. However, these proteins were upregulated in 3T3 cells of the SMG group on day 5, suggesting that these cells were rescued from the arrest and retrieved a higher proliferation. A down-regulation of cell cycle-related proteins was observed in 3T3 cells of both SMG and control groups on day 7. In conclusion, SMG results in the attenuation of cell proliferation during the initial exposure to SMG, but the cells will adapt to this condition and retrieve normal proliferation by increasing the expression of cell cycle regulators.