EFFECT OF MECHANICAL STRETCH ON APOPTOSIS AND BAX/BCL-2 PROTEIN EXPRESSION OF HUMAN ORAL SQUAMOUS CELL CARCINOMA KB CELLS IN VITRO

Objective: To investigate the effect of mechanical stretch force on the apoptosis of Human oral Squamous Cell Carcinoma KB Cells cultured in vitro. Method: The KB cells were subjected to cyclic equibiaxial stretch forces for different regimens (squarewave, 10% and 15% elongation amplitude, 0.5Hz, 24h) using Flexcell4000TM strain unit. Apoptotic levels of the KB cells were quantified by flowcytometer right after the stretch application. The ratios of bax/bcl-2 was analysed by RFQ-PCR. Result: different stretch force (10% or 15% elongation) led to a increase of apoptosis rate of KB cells compared with the control, the apoptosis rate of 15% elongation was significantly higher than 10% elongation (P< 0.05), different stretch force led to a decrease of bcl-2 mRNA expressing of KB cells compared with the control, the bcl-2 mRNA expressing of 15% elongation was significantly lower than 10% elongation (P< 0.05), different stretch force led to an increase of bax mRNA expressing of KB cells compared with the control, the bax mRNA expressing of 15% elongation was significantly higher than 10% elongation (P< 0.05). Conclusion: Stretching force can affect apoptosis in the KB cells culture. Different force loading magnitudes could induce the KB cells apoptosis by altering bax/bcl-2 protein expression.