Low power ultrasound inhibits cell proliferation and invasion of human cancer cells in vitro

Background: Applications of ultrasound in medicine for therapeutic purposes have been accepted, and they have several beneficial uses for many years. However, the outcome of low power ultrasound waves on cell proliferation, especially cell cycle progression and invasion as well as their associated genes on human breast and cervical cancer cells has not been investigated yet. Therefore, we examined the effect of low power ultrasound on BT20, BT20-E6/E7 and HeLa cell lines. Materials and Methods: BT20, BT20-E6/E7 and HeLa cell lines were used in this study. On the other hand, cell proliferation, cell cycle, and invasion assays were applied to study the effect of low ultrasound irradiation on these cell lines. Meanwhile, western blot was performed to study the expression patterns of some selected genes associated with this effect. Results: We found that low power ultrasound inhibits cell proliferation and provokes G0-G1 cell cycle arrest and reduction of S as well as an increase in the G2-M phase of HeLa cells in comparison with the untreated cells. This is accompanied by a down-regulation of Cdk-6 (cyclin dependent kinase) which is a major control switch for the cell cycle. Moreover, low power ultrasound inhibits cell invasion and consequently down-regulates the expression of Id-1, caveolin, and EGF-R which are widely considered as main regulators of cell invasion and metastasis of human cancer. Conclusion: These results suggest that application of low power ultrasound on human breast and cervical cancer could be an effective method to reduce cell proliferation and invasion of these cancers.