Effects of silencing survivin gene by RNA interference on cell apoptosis using ultrasound targeted microbubble destruction techniques / 肿瘤

ABSTRACT

Objective:To transfect genes using ultrasound targeted microbubble destruction (UTMD) techniques and observe the effects of RNA interference on cervical cancer (HeLa) cell line in silencing survivin gene and inducing apoptosis. Methods: Recombinant expression plasmid of short hairpin RNA (shRNA) targeting survivin gene was constructed. It was co-treated with microbubbles and transfected to cultured HeLa cells followed by exposure to ultrasound (P+UTMD group). Moreover, blank control group (C), plasmid group (P), ultrasound exposure group (US), plasmid and ultrasound exposure group (P+US), plasmid+ Lipofectamine group (P+L) were used as controls, respectively. Transfection efficacy was evaluated by observing the red fluorescence in the cells by fluorescent microscopy and flow cytometry(FCM). Ultrasound intensity and exposure time were optimized. Cell apoptosis was investigated using flow cytometry analysis, Hoechst staining, and DNA ladder method. Expression of survivin mRNA was assessed by RT-PCR. Results: Restrictive enzyme digestion and sequencing analysis verified that the recombinant plasmid was successfully constructed. UTMD significantly increased gene transfection efficacy in cultured HeLa cells (P<0.01). Gene transfer was the most prominent at ultrasound intensity of 1.0 W/cm2 and exposure time of 3 min (P<0.01). RT-PCR showed that the expression of survivin mRNA in P+UTMD group was inhibited by (83.33±2.73)%. The differences were significant compared with any other groups (P<0.01). FCM analysis showed that the apoptosis ratio in P+UTMD group was significantly increased as compared with other groups (P<0.01). Hoechst staining and DNA ladder showed that apparent apoptosis and DNA ladder were detected only in P+UTMD and P+L groups. Conclusions:UTMD effectively enhances the transfection efficacy of expression plasmid. It is a novel and effective non-viral gene transfer system and has promising foreground. UTMD mediates RNA interference silenced survivin gene and induces significant cell apoptosis, which provides a new method for tumor research and gene therapy.