Hydrostatic Compressive Stress Promotes MC3T3-E1 Cell Proliferation Through ROCK-Dependent Regulation of Cyclin D1 and CDK4.

Mechanical stimulation plays a pivotal role in bone remodeling by increasing interstitial hydrostatic pressure and generating compressive stress within the bone microenvironment. However, the effects of different loading conditions on osteoblast responses and the underlying mechanotransduction mechanisms remain incompletely understood. In the present study, we utilized the MechanoCulture TR hydrostatic stimulation system to evaluate the effects of different hydrostatic compressive stress magnitudes and loading durations on MC3T3-E1 cells and elucidate the role of the ROCK signaling pathway in stress-induced proliferation. Among the conditions tested at a fixed frequency of 0.05 Hz, hydrostatic compressive stress at 5 kPa for 45 min elicited the strongest proliferative response and was accompanied by F-actin reorganization. Furthermore, compressive loading significantly upregulated the expression of ROCK, Cyclin D1, and CDK4. Conversely, inhibition of ROCK with Y-27632 reduced ROCK activity, altered F-actin organization, suppressed cell proliferation, and attenuated compression-induced upregulation of Cyclin D1 and CDK4. In conclusion, hydrostatic compressive stress promotes MC3T3-E1 cell proliferation through ROCK-dependent regulation of Cyclin D1 and CDK4. These findings support an important role for ROCK in the proliferative response of osteoblasts to hydrostatic compressive stress.