This study aims at determining the therapeutic effect of knockdown of signal transducers and activators of transcription3（STAT3） gene expression by short interference RNA（siRNA） on transplanted Lewis lung cancer in mice in vivo. pSilencer 2.1-U6 STAT3 siRNA against STAT3（STAT3 siRNA） was synthesized. Lewis lung cancer cells were inoculated subcutaneously into C57BL/6 mice. Seven days after inoculation, the tumor-bearing mice were randomly divided into 3 groups and received intratumoral injection of （1） vehicle（PBS solution）, （2） vector（negative control）, and （3） STAT3 siRNA. Tumor volume and weight were calculated. Tumors and the lungs were excised for 21 days after inoculation. Expressions of STAT3, vascular endothelial growth factor（VEGF）, and matrix metalloproteinase-2（MMP2） were analyzed by RT-PCR, Western blot, and immunohistochemical staining. HE staining and TUNEL assay were used to confirm the apoptosis of tumors. The synthetic STAT3 siRNA effectively suppressed tumor growth, prevented tumor from pulmonary metastasis, and induced tumor apoptosis in vivo compared with vehicle and vectore in controls. It significantly inhibited STAT3 expression to contribute to downregulation of VEGF and MMP2 expression within tumors in vivo. This study demonstrates that STAT3 siRNA can effectively inhibit the expression of STAT3 gene within tumors, leading to suppression of tumor growth, prevention of cancer from pulmonary metastasis, and enhancing apoptosis of the transplanted Lewis lung cancer in mice in vivo.
WANG Chun-guangWANG Rong-youSUN MeiLI Jin-dongGAO NanZHANG Xing-yiSHI Dong-leiJIN Cheng-yan
To construct a lentiviral shRNA vector targeting rat CD40 gene and detect its effectiveness of gene silencing in dendritic cells（DCs）, specific siRNA targets with short hairpin frame were designed and synthesized according to the mRNA sequence of rat CD40 gene. DNA oligo was cloned into lentiviral expression vector, and then PCR and sequencing analyses were conducted to verify the constructs. The verified plasmids were transfected into 293T cells that over-express recombinant CD40 in order to select the most effective siRNA targets, shRNA lentiviruses from the selected constructs were propagated and harvested with a virus packaging system, and the virus titers were determined. Western blot and Real-time PCR were performed to determine CD40 expression level in the virusinfected dendritic cells. PCR and sequencing analyses reveal that shRNA plasmids of four targets were successfully constructed. The optimal interfering target was selected, and the virus with a titer of 5 × 10^7 TU/mL was successfully packaged. CD40 expression in rat DCs was knockdown at both mRNA and protein levels by virus infection. In comparison to that of control groups, CD40 mRNA expression and protein expression were decreased by 60.9% and 61.2%, respectively. We have successfully constructed recombinant lentiviral shRNA expression vector targeting rat CD40 gene that can effectively down-regulate CD40 gene expression at mRNA and protein levels in rat DC.
