title: Sonoporation by low-frequency and low-power ultrasound enhances chemotherapeutic efficacy in prostate cancer cellsin vitro.
abstract: Combination therapy is used to optimize anticancer efficacy and reduce the toxicity and side-effects of drugs upon systemic administration. Ultrasound (US) combined with micro-bubbles (UM) enhances the intracellular uptake of cytotoxic drugs by tumor cells, particularly drug-resistant cells. In the present study, low-frequency and low-energy US (US irradiation conditions: frequency, 21 kHz; power density, 0.113 W/cm2; exposure time, 2 min at a duty cycle of 70%; and valid treatment time, 84 sec) were used in combination with microbubbles (100μl/ml) to deliver mitoxantrone HCl (MIT) to DU145 cells. The results showed that UM did not change the cell viability in the short- or long-term. However, UM statistically enhanced the therapeutic effects and up to 31.26±3.34% of the cells exposed to UM were permeabilized compared with 9.74±2.55% of cells in the control, when using calcein (MW, 622.53) as a fluorogenic marker. Notably, UM affected the migration capability of the DU145 cells at 6 h post-treatment. In conclusion, the ultrasonic parameters used in the present study enhanced the chemotherapeutic effect and reduced the unwanted side-effects of MIT.
authors.affiliation: Department of Ultrasound in Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Institute of Ultrasound in Medicine, Shanghai 200233, P.R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Wen-Kun
authors.initials: WK
authors.lastname: Bai
authors.forename: E
authors.initials: E
authors.lastname: Shen
authors.forename: Bing
authors.initials: B
authors.lastname: Hu
keywords: low-energy ultrasound; low-frequency ultrasound; microbubble; mitoxantrone delivery