siRNA降低COX-2基因表达对肝癌细胞系HepG2增殖的影响

Construction of eukaryotic expression vectors expressing siRNAs targeting the HCCR2 gene and their transfection into PANC1 cells

AIM: To construct eukaryotic expression vectors expressing small interfering RNAs (siRNAs) targeting the human cervical cancer oncogene 2 (HCCR2) gene and transfect them into human pancreatic cancer cell line PANC1 to obtain a cell line stably transfected with the HCCR2 siRNA plasmid.

METHODS: Multiple siRNAs targeting the HCCR2 gene were designed, chemically synthesized, and cloned into the eukaryotic expression vector pGCsi-H1/Hygro/NEGative. The resulting recombinant vectors were identified by direct sequencing. After the recombinant pGCsi-HCCR plasmids were co-transfected with an HCCR eukaryotic expression vector into 293T cells, the protein expression of HCCR-2 was analyzed by Western blotting to identify the pGCsi-HCCR vector that had the highest gene knockdown efficiency. This recombinant vector was then transfected into PANC1 cells with LipofectamineTM 2000. G418-resistant clones were selected to obtain a stably transfected cell line. The expression of HCCR2 protein in stably transfected cell line was detected by Western blot.

RESULTS: The pGCsi-HCCR-3 plasmid had the highest gene knockdown efficiency and was used to transfect PANC1 cells. Western blotting analysis demonstrated that HCCR2 expression was significantly inhibited in PANC-1 cells stably transfected with the pGCsi-HCCR-3 plasmid compared to cells transfected with the empty vector.

CONCLUSION: Eukaryotic expression vectors expressing siRNAs targeting the HCCR2 gene were successfully constructed and a PANC-1 cell line stably transfected with the pGCsi-HCCR-3 plasmid was successfully established.

Transfection with siRNA against ERK1/2 inhibits IGF-1-induced stem cell factor expression in colonic smooth muscle cells

AIM: To investigate how insulin-like growth factor-1 (IGF-1) regulates the expression of stem cell factor (SCF) in colonic smooth muscle cells (SMCs).

METHODS: After rat colonic SMCs were treated with different concentrations of IGF-1 (0, 50, 100, 150 μg/L) for different durations (0, 5, 15, 30, 45, 60 min), the levels of phosphorylated ERK1/2 and SCF were determined by RT-PCR and Western blot. Rat colonic SMCs were then transfected with siRNA against ERK1/2 to examine the impact of ERK1/2 down-regulation on IGF-1-induced SCF expression.

RESULTS: After treatment with IGF-1, the level of phosphorylated ERK1/2 in colonic SMCs reached a peak at about 15 min (0.417 ± 0.036 vs 0.101 ± 0.015; P < 0.05). The optimal concentration of IGF-1 to induce the expression of phosphorylated ERK1/2 and SCF was 100 μg/L (0.790 ± 0.051 vs 0.336 ± 0.013; 0.765 ± 0.061 vs 0.289 ± 0.021, both P < 0.05). After treatment with IGF-1, the expression levels of phosphorylated ERK1/2, total ERK1/2, and SCF in colonic SMCs transfected with siRNA against ERK1/2 were lower than those in the control group (0.284 ± 0.021 vs 0.732 ± 0.005; 0.256 ± 0.015 vs 0.712 ± 0.023; 0.219 ± 0.020 vs 0.673 ± 0.013; 0.621 ± 0.027 vs 1.725 ± 0.012; 0.821 ± 0.019 vs 1.751 ± 0.043; 0.275 ± 0.061 vs 0.531 ± 0.047; all P < 0.05).

CONCLUSION: IGF-1 treatment up-regulated the expression of phosphorylated ERK1/2 and SCF in colonic SMCs, while transfection with siRNA against ERK1/2 down-regulated IGF-1-induced expression of phosphorylated ERK1/2 and SCF, suggesting that the ERK/MAPK pathway may be involved in IGF-1-induced expression of phosphorylated ERK1/2 and SCF.

Construction of shRNA expression plasmids targeting the Pyk2 gene and their expression in Lovo cells

AIM: To construct the recombinant small hairpin RNA (shRNA) plasmids targeting the proline-rich tyrosine kinase 2 (Pyk2) gene (pGCsi-Pyk2 shRNA) and detect their expression in Lovo cells.

METHODS: Three pairs of Pyk2 shRNA sequences were designed and ligated to the pGCsi vector that contains U6 promoter and hygromycin B to obtain shRNA expression plasmids targeting the Pyk2. The recombinant pGCsi-Pyk2 shRNA plasmids were introduced into Lovo cells by liposome-mediated transfection and selected with hygromycin B. The expression of Pyk2 mRNA and protein was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively.

RESULTS: Restriction enzyme digestion and sequence analysis showed that recombinant pGCsi-Pyk2 shRNA plasmids were successfully constructed. The expression levels of Pyk2 mRNA and protein in Lovo cells transfected with pGCsi-Pyk2 shRNA plasmids were significantly lower than those in Lovo cells transfected with empty or negative plamsids.

CONCLUSION: Recombinant pGCsi-Pyk2 shRNA plasmids are successfully constructed. Their transfection can silence the expression of Pyk2 gene in Lovo cells. The pGCsi-Pyk2 shRNA plasmids obtained lay a foundation for further study of the role of the Pyk2 gene in the pathogenesis of colorectal cancer.