title: [Antitumor effects of low-frequency ultrasound combined with adriamycin on human leukemia multidrug resistance cell line K562/A02].
abstract: OBJECTIVE
  Researches have shown that ultrasound can enhance the sensitivity of tumor cells towards chemotherapy drugs, thus to inhibit cell proliferation. This study was to investigate the antitumor effect of low-frequency ultrasound combined with adriamycin on human leukemia multidrug resistance (MDR) cell line K562/A02.
  
  
  METHODS
  K562/A02 cells were divided into four groups: blank control group, adriamycin group, ultrasound group, and adriamycin plus ultrasound group. The trypan blue dye exclusion assay and MTT assay were used to determine the viability and proliferation of K562/A02 cells, while Wright's stain and flow cytometry were used to determine the apoptosis and the concentration of adriamycin. The expression of P-glycoproteins (P-gp) was detected using immunocytochemistry.
  
  
  RESULTS
  Ultrasound (20 kHz, 0.25 W/cm2, 60s) combined with adriamycin (7.5 microg/mL) induced more apoptosis of K562/A02 cells than adriamycin alone. Compared with the adriamycin group, ultrasound at a frequency of 20 kHz and an intensity of 0.5 W/cm2 exerted an acute killing effect on cells. Ultrasound increased the intracellular concentration of adriamycin and promoted apoptosis of K562/A02 cells, but did not change the expression of P-gp on the cell membrane.
  
  
  CONCLUSIONS
  Ultrasound at a frequency of 20 kHz, an intensity of 0.25 W/cm2 and duration of 60s can enhance the killing effect of adriamycin on K562/A02 cells.
authors.affiliation: Department of Hematology, Zhongda Hospital, Southeast University, Nanjing, Jiangsu, China.
authors.forename: Qing-Qi
authors.initials: QQ
authors.lastname: Meng
authors.forename: Bao-An
authors.initials: BA
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.forename: Ze-Ye
authors.initials: ZY
authors.lastname: Shao
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.forename: Hui-Hui
authors.initials: HH
authors.lastname: Zhao
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D004317:Doxorubicin / Q000378:metabolism / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D020014:K562 Cells; D014465:Ultrasonics
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D004317:Doxorubicin