Takashi Kondo1, Toru Yoshida2, Ryohei Ogawa3, Mariame A Hassan3, Yukihiro Furusawa3, Qing-Li Zhao3, Akihiko Watanabe4, Akihiro Morii4, Loreto B Feril5, Katsuro Tachibana5, Hiroshi Kitagawa6, Yoshiaki Tabuchi7, Ichiro Takasaki7, Mohammad H Shehata8, Nobuki Kudo9, Kazuhiro Tsukada2. 1. Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan. kondot@med.u-toyama.ac.jp. 2. Second Department of Surgery, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan. 3. Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan. 4. Department of Urology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan. 5. Department of Anatomy, Fukuoka University School of Medicine, Fukuoka, Japan. 6. Laboratory of Animal Histophysiology, Division of Animal Science, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe, Japan. 7. Life Science Research Center, University of Toyama, Toyama, Japan. 8. Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan. 9. Laboratory of Biomedical Instrumentation and Measurements, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan.
Abstract
PURPOSE: In this study, the effects of low-intensity pulsed ultrasound (LIU) as an adjuvant to doxorubicin (DOX) treatment was further investigated in comparison to hyperthermia as another widely used adjuvant. The effects were compared with respect to cell killing and apoptosis induction in U937 cells. Human primary liver cancer (PLC) cells were also used to evaluate the effects of the combinations. The use of an echo contrast agent was investigated for further enhancement of cytotoxicity. Finally, the acoustic mechanisms involved were investigated. METHODS: The effects of different treatment regimens on cell viability were determined using the Trypan blue dye-exclusion test. Apoptosis induction was detected by flow cytometry using fluorescein isothiocyanate-annexin V and propidium iodide staining. The mechanistic study involved electron paramagnetic spin trapping for detecting free radical formation as an indicator of the occurrence of inertial cavitation and spectrophotometry for sucrose hydrolysis as an indicator for noncavitational effects. RESULTS: The combination treatments exerted synergistic effects on cytotoxicity depending on the acoustic conditions used. The use of LIU as an adjuvant to DOX treatment was shown to be superior to the use of hyperthermia as an adjuvant. Moreover, the combination seems to be promising for other cancer types provided that the acoustic conditions are properly selected with respect to drug concentration. The key ultrasound mechanism responsible for the synergism observed was shown to be the production of free radicals by inertial cavitation. Non-cavitational forces were also shown to contribute to the effect. CONCLUSION: This study is motivating to engage in in vivo research with various cancer types as a step toward clinical applicability and is emphasizing on the importance of developing therapeutic protocols for setting LIU parameters with respect to other therapeutic conditions.
PURPOSE: In this study, the effects of low-intensity pulsed ultrasound (LIU) as an adjuvant to doxorubicin (DOX) treatment was further investigated in comparison to hyperthermia as another widely used adjuvant. The effects were compared with respect to cell killing and apoptosis induction in U937 cells. Human primary liver cancer (PLC) cells were also used to evaluate the effects of the combinations. The use of an echo contrast agent was investigated for further enhancement of cytotoxicity. Finally, the acoustic mechanisms involved were investigated. METHODS: The effects of different treatment regimens on cell viability were determined using the Trypan blue dye-exclusion test. Apoptosis induction was detected by flow cytometry using fluorescein isothiocyanate-annexin V and propidium iodide staining. The mechanistic study involved electron paramagnetic spin trapping for detecting free radical formation as an indicator of the occurrence of inertial cavitation and spectrophotometry for sucrose hydrolysis as an indicator for noncavitational effects. RESULTS: The combination treatments exerted synergistic effects on cytotoxicity depending on the acoustic conditions used. The use of LIU as an adjuvant to DOX treatment was shown to be superior to the use of hyperthermia as an adjuvant. Moreover, the combination seems to be promising for other cancer types provided that the acoustic conditions are properly selected with respect to drug concentration. The key ultrasound mechanism responsible for the synergism observed was shown to be the production of free radicals by inertial cavitation. Non-cavitational forces were also shown to contribute to the effect. CONCLUSION: This study is motivating to engage in in vivo research with various cancer types as a step toward clinical applicability and is emphasizing on the importance of developing therapeutic protocols for setting LIU parameters with respect to other therapeutic conditions.
Authors: S Umemura; N Yumita; Y Okano; M Kaneuchi; N Magario; M Ishizaki; K Shimizu; Y Sano; K Umemura; R Nishigaki Journal: Cancer Lett Date: 1997-12-23 Impact factor: 8.679