Enhanced Cytotoxic Effect of Ara-C by Low Energy Ultrasound to HL-60 Cells

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 09671777
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Otorhinolaryngology
• Research Institution: Fukuoka University
• Principal Investigator: TSUJITA Naotaka Fukuoka Univ., Sch. Medicine, Assist. Prof, 医学部, 助手 (20248496)
• Co-Investigator(Kenkyū-buntansha): MIYAGI Morimichi Fukuoka Univ., Sch. Med.,, Assist. Prof, 医学部, 助手 (60289543)
• Project Period (FY): 1997 – 1999
• Keywords: Ultrasound / Chemotherapy / Lymphocytes / Ara-C / SEM

Research Abstract

Clonogenic assay was tested in order to determine the effects of low energy ultrasound (US) on HL-60 cells in the presence of cytosine arabinoside (Ara-C). HL-60 cells were exposed to ultrasound at an intensity of 0.3 W/cmィイD12ィエD1 (48 kHz). Cells were then cultured by methylcellulose method for 8 days and the number of colonies was statistically analyzed (one-way and two-way ANOVA). Ultrasound exposure alone for 120 seconds resulted in no significant decrease of colonies compared to non-treated cells (PィイD20ィエD2 = 0.1426). Significant differences (PィイD20ィエD2 < 0.005) were obtained between ultrasound treated and untreated cells in the presence of various concentrations of Ara-C (2×10ィイD1-9ィエD1, 1×10ィイD1-8ィエD1, 2×10ィイD1-8ィエD1, 5×10ィイD1-8ィエD1, 1×10ィイD1-7ィエD1M). Dose response studies revealed a significant enhancement of the anti-proliferative effects on colonies of HL-60 cells treated with ultrasound and Ara-C (two-way ANOVA/US ; PィイD20ィエD2=0.0000, 8.16%, Ara-C ; PィイD20ィエD2=0.0000, 88.91%). At lower concentration of Ara-C (0, 2×10ィイD1-9ィエD1, 1×10ィイD1-8ィエD1, 2×10ィイD1-8ィエD1M), the effects of ultrasound were greater than that of Ara-C (two-way ANOVA/US ; PィイD20ィエD2=0.0000, 71.33%, Ara-C ; PィイD20ィエD2=0.0000, 14.99%). It is suggested that ultrasound irradiation is more effective at relatively low non-toxic Ara-C concentration levels. Morphological evaluation of ultrasound irradiated cells with scanning electron microscopy showed minor disruption of cell surface and disappearance of microvilli. These observations suggests that low energy ultrasound altered the cell membrane thus resulting in change in Ara-C uptake into HL-60 cells.