Preparation of Nanobubbles Carrying Androgen Receptor siRNA and Their Inhibitory Effects on Androgen-Independent Prostate Cancer when Combined with Ultrasonic Irradiation

Abstract

ObjectiveThe 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).Materials and MethodsNanobubbles 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.ResultsThe 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.ConclusionNanobubbles carrying AR siRNA could be potentially used as gene vectors in combination with ultrasonic irradiation for the treatment of AIPC.

Downregulation of Renal G Protein–Coupled Receptor Kinase Type 4 Expression via Ultrasound‐Targeted Microbubble Destruction Lowers Blood Pressure in Spontaneously Hypertensive Rats

“…5‐Carboxyfluorescein (5‐FAM)–labeled GRK4 siRNA was synthesized by RIBOBIO (Gangzhou, China) for fluorescence tracing studies. Microbubbles carrying GRK4 siRNA were prepared using poly‐L‐lysine (PLL) and the electrostatic adsorption method . The PLL solution (1 mg/mL) was prepared with sterile double‐distilled water.…”

“…Microbubbles carrying GRK4 siRNA were prepared using poly-L-lysine (PLL) and the electrostatic adsorption method. 11 The PLL solution (1 mg/mL) was prepared with sterile double-distilled water. The PLL solution was then mixed with the blank microbubbles at a 1:1 (v/v) ratio and incubated at 4°C for 30 minutes.…”

Gene interference strategies as a new tool for the treatment of prostate cancer

“…They found that, coupled with ultrasonic irradiation, the nanobubbles carrying AR siRNA could significantly inhibit the growth of C4-2 cells and LNCaP cells. This experimental approach could be a support for the use of nanobubbles carrying AR siRNA in combination with ultrasonic irradiation as a potential effective therapy for androgen-independent PCa [117].…”

“…The identification of molecular mechanisms underlying the transition from primary tumor to castration-resistant prostate metastasis is critical for predicting patient prognosis and the most effective therapy. Dramatically, poor survival rates and disease recurrence are associated with the LICAM Decreases migration and invasion in metastatic murine model Sung et al [116] AR Inhibits growth of C4-2 and LNCaP cells Wang et al [117] elevated expression of a splice variant of the Kruppel-like factor 6 (KLF6) tumor suppressor gene (termed as KLF6-SV1). In this study, PCa cells overexpressing KLF6-SV were associated with faster metastasization and more frequent dissemination to lymph nodes, bone, and brain.…”

Inhibition of prostate cancer growth using doxorubicin assisted by ultrasound-targeted nanobubble destruction

“…The results showed that this technique had good inhibitory effects on tumors. 11,12 However, chemotherapeutic drugs assisted by US-targeted NB destruction (UTND) for the treatment of tumors and the underlying mechanism still require further investigation. Therefore, we applied lipid NBs and the classic broad-spectrum chemotherapeutic drug doxorubicin (DOX) to treat prostate cancer using UTND in this study.…”