Targeted therapy of Apt-siRNA combining with docetaxel for PSMA-positive prostate cancer and monitoring imaging of 99Tc m-Apt-siRNA / 中华核医学与分子影像杂志

ABSTRACT

Objective:Apt-A10-3.2 (aptamer of prostate specific membrane antigen (PSMA)) can be used as a specific ligand for early diagnosis and targeted treatment of prostate cancer. Mouse double minute 2 homolog (MDM2) is closely related to the malignancy of prostate cancer, and MDM2 small interfering RNA (siRNA) can silence MDM2 gene through RNA interference. To design a novel chimera of PSMA Apt-MDM2 siRNA and combine it with docetaxel (DTX) to explore a new diagnosis and treatment model combining targeted therapy of PSMA-positive prostate cancer with 99Tc m-chimera imaging monitoring. Methods:Apt-siRNA were obtained by covalent connection of PSMA Apt-A10-3.2 and MDM2 siRNA, which was combined with DTX to treat PSMA-positive prostate cancer cell lines (22RV1 and LNCaP). Cell lines were treated with Apt-siRNA alone or in combination with DTX. The levels of MDM2 and apoptosis-related proteins (B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X (Bax), poly ADP-ribose polymerase (PARP), caspase-3) were detected by Western blot, which were used to evaluate the therapeutic effect. Fifteen BALB/c mice bearing 22RV1 xenografts were treated with PBS, DTX+ Apt-siRNA (200 pmol) and DTX+ Apt-siRNA (400 pmol), respectively. Tumor volume and MDM2 level were observed, and 99Tc m-Apt-siRNA SPECT imaging was performed to obtain the tumor/muscle (T/M) ratio. One-way analysis of variance, Tukey′s test and linear regression analysis were used for data analysis. Results:The levels of MDM2 protein were significantly decreased by Apt-siRNA (0.25±0.02, F=183.40, P<0.001; 0.56±0.03, F=37.15, P<0.001) in 22RV1 and LNCaP cells. After the treatment of Apt-siRNA+ DTX, the levels of Bcl-2 were significantly decreased, and the levels of Bax, PARP and caspase-3 were significantly increased. MDM2 protein level (400 pmol 0.59±0.12; F=49.99, P=0.023) and tumor volume (400 pmol (0.22±0.07) cm 3;F=71.30, P=0.039) were significantly inhibited by Apt-siRNA+ DTX in mice bearing 22RV1 xenografts. As for 99Tc m-Apt-siRNA SPECT imaging in vivo, T/M ratio of treatment group was significantly decreased (400 pmol 2.07±0.22; F=34.99, P=0.022), and there was a linear regression relationship between T/M ratio and the expression level of MDM2 ( R2=0.875, P<0.001). Conclusion:Apt-siRNA combined with DTX can effectively inhibit the progression of prostate cancer, and realize visual targeted diagnosis and treatment of PSMA-positive prostate cancer by coupling radionuclide technetium.