title: Preparation of nanobubbles carrying androgen receptor siRNA and their inhibitory effects on androgen-independent prostate cancer when combined with ultrasonic irradiation.
abstract: OBJECTIVE
  The objective of this study was to investigate nanobubbles carrying androgen receptor (AR) siRNA and their in vitro and in vivo anti-tumor effects, when combined with ultrasonic irradiation, on androgen-independent prostate cancer (AIPC).
  
  
  METHODS
  Nanobubbles carrying AR siRNA were prepared using poly-L-lysine and electrostatic adsorption methods. Using C4-2 cell activity as a testing index, the optimal irradiation parameters (including the nanobubble number/cell number ratio, mechanical index [MI], and irradiation time) were determined and used for transfection of three human prostate cancer cell lines (C4-2, LNCaP, and PC-3 cells). The AR expression levels were investigated with RT-PCR and Western blot analysis. Additionally, the effects of the nanobubbles and control microbubbles named SonoVue were assessed via imaging in a C4-2 xenograft model. Finally, the growth and AR expression of seven groups of tumor tissues were assessed using the C4-2 xenograft mouse model.
  
  
  RESULTS
  The nanobubbles had an average diameter of 609.5±15.6 nm and could effectively bind to AR siRNA. Under the optimized conditions of a nanobubble number/cell number ratio of 100∶1, an MI of 1.2, and an irradiation time of 2 min, the highest transfection rates in C4-2, LNCaP, and PC-3 cells were 67.4%, 74.0%, and 63.96%, respectively. In the C4-2 and LNCaP cells, treatment with these binding nanobubbles plus ultrasonic irradiation significantly inhibited cell growth and resulted in the suppression of AR mRNA and protein expression. Additionally, contrast-enhanced ultrasound showed that the nanobubbles achieved stronger signals than the SonoVue control in the central hypovascular area of the tumors. Finally, the anti-tumor effect of these nanobubbles plus ultrasonic irradiation was most significant in the xenograft tumor model compared with the other groups.
  
  
  CONCLUSIONS
  Nanobubbles carrying AR siRNA could be potentially used as gene vectors in combination with ultrasonic irradiation for the treatment of AIPC.
authors.affiliation: Department of Urology, Daping Hospital & Institute of Surgery Research, Third Military Medical University, Chongqing, China.
authors.forename: Luofu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Ultrasound, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Ultrasound, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Kaibin
authors.initials: K
authors.lastname: Tan
authors.affiliation: Department of Ultrasound, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Ultrasound, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Haipeng
authors.initials: H
authors.lastname: Tong
authors.affiliation: Department of Ultrasound, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Xiaozhou
authors.initials: X
authors.lastname: Fan
authors.affiliation: Department of Ultrasound, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Kejing
authors.initials: K
authors.lastname: Fang
authors.affiliation: Department of Ultrasound, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Li
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D064593:Heterografts / Q000473:pathology; D006801:Humans; D008297:Male; D051379:Mice; D049329:Nanostructures; D011471:Prostatic Neoplasms / Q000235:genetics / Q000532:radiotherapy / Q000628:therapy*; D034741:RNA, Small Interfering; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D014464:Ultrasonic Therapy
chemical_list: C410798:AR protein, human; D034741:RNA, Small Interfering; D011944:Receptors, Androgen