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Objective:To investigate the infloence of RNA interference targeting P13K p85α on the invasion and metastasis of colorectal cancer cells. Methods:Foor shRNA vectors and one negative control vector were designed and stably transfected into LoVo cells. Western blotting analysis was used to screen for the groop which had the highest inhibitory rate; the cells were sobjected to woond closore assay and transwell assay to determine the migration of LoVo cells after stable transfection. Results: Western blotting analysis showed that cells transfected with shRNA/324 vector had the strongest inhibition of P13K p85α protein, with the inhibition rate being 77% , and cells in this groop were osed for woond closore assay and transwell assay. Wound cloaore assay showed that the healing ability of P13K p85α-depleted cells was significantly lower than that of the control cells (P<0.05). Transwell assay showed that the cells passing the polycsrhonate membranes was significantly less in P13K p85α-knockdown cells than in the control cells (P<0.05). Conclusion:Depletion of P13K p85α protein can obvioosly inhibit the migration of LoVo cells. P13K p85α may be a new therapeotic target for treatment of colorectal cancer metastasis.
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Objective: To investigate the effect of RNA interference (RNAi) targeting AKT1 and PI3K P85 on the proliferation and invasion of breast carcinoma MCF-7 cells. Methods: The recombinant adenovirus expression vector, which contained short hairpin RNA (shRNA) targeting open reading frames of AKT1 and PI3K P85 (rAd5-siAKT1-siPI3K), was transfected into human breast carcinoma MCF-7 cells. AKT1 and PI3K P85 mRNA and protein expressions were detected by real-time PCR and Western blotting analysis. The expressions of PCNA, cyclinD1, and P53 were also detected by Western blotting analysis. The proliferation and apoptosis of MCF-7 cells were measured by MTT, flow cytometry and 2-dementinal and 3-dementional matrigel assay. Results: Recombinant adenovirus vector rAd5-siAKT1-siPI3K dramatically down-regulated AKT1 and PI3K P85 mRNA and protein expressions in MCF-7 cells; the downstream factors PCNA and cyclin D1 were also down-regulated, while P53 was up-regulated. Growth of MCF-7 cells was inhibited by over 50% in rAd5-siAKT1-siPI3K group as measured by MTT assay, and cell cycle was arrested in G_1/G_0 phase compared with untransfected and rAd5-siCtrl transfected groups. Cell growth on matrigel matrix showed normal cell shapes, while the cells in rAd5-siAKT1-siPI3K transfected group were detached from the matrix or grew in scattered clustering patterns, forming only small aggregates. Conclusion: shRNA targeting AKT1 and PI3K P85 can significantly down-regulate the expression of AKT1 and PI3K P85 in breast carcinoma MCF-7 cells, and inhibit the growth of MCF-7 cells in vitro.
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Objective To construct a short hairpin RNA (shRNA) adenovirus vector targeting P85 and protein kinase B1 (PKB1/Akt1) and study its effects on the growth of SGC-7901 human gastric adenocareinoma cells. Methods P85 and Aktl shRNA expression frames were subcloned to pGSadeno adenovirus vector with homologous recombination technology to construct pGSadeno-P85 + Akt1 (rAd5-P + A) vector. After screening and amplification, the recombinant adenovirus vector was digested with PacI and transfected into SGC-7901 cells and then its titer and transfection efficiency were detected with fluorescent microscope. P85 and Akt1 mRNA protein expression was identified with real-time PCR and Western blot. The proliferative activity of tumor cells was evaluated with MTr assay and flow cytometry in vitro, rAd5-HK and rAd5-P + A mediated by adenovirus were injected into the established subcutancous SGC-7901 gastric adenocarcinoma in nude mice. During the observation period of 21 days, tumor volume was measured every 3 days to further testify the anti-tumor effect of rAd5-P + A on the SGC-7901 gastric adenocarcinoma cells and cell in situ apoptosis was detected with TUNEL assay. Results The adenovirus vector rAd5-P + A was successfully constructed and it dramatically downregulated P85 and Akt1 mRNA expression in SGC-7901 gastric adenocarcinoma cells. Compared with a control group of SGC-7901 cells and cells transfected with general adenovirus rAd5-HK as control, P85 and Akt1 protein expression 48 h and 72 h after rAd5-P + A transfection was decreased by 57.5% and 63. 7%, 67. 8% and 75.6% with statistical significance(P = 0. 005, P = 0. 003). Cell proliferative activity in rAd5-P + A transfected cells was suppressed from the second day (P <0. 001) and the decreased P85 and Akt1 expression was accompanied by 5.9% -7. 1% decrease of S phase fraction and 12. 1% - 13.7% increase of G0/G1 phase. The tumor volume of rAd5-P + A treated group was smaller than that of the control and rAd.5-HK group with statistical significance (F = 9. 871, P = 0. 025) . Moreover, rAd5-P + A could induce cell in situ apoptosis. Conclusions Adenovirus-mediated targeting P85 and Akt1 shRNA can inhibit the growth of SGC-7901 human gastric adenocarcinoma cells and this may provide a new strategy of combination gene therapy in gastric adenocarcinoma.
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In order to assess whether gene transfection could be mediated by ultrasound in associa- tion with P85 and find the appropriate parameters of ultrasound irradiation, the effects of ultrasound with or without P85 on gene transfection of HepG2 cells were examined. The HepG2 cells were irra- diated by ultrasound at 1 MHz, 0.4-2.0 W/cm2 and 50% duty cycle with plasmid encoding enhanced green fluorescent protein (EGFP) as a report gene. Forty-eight h later, the expression of EGFP was detected under the fluorescence microscopy. Transfection efficacy was quantitatively assessed by flow cytometry, and cell viability was evaluated by trypan blue exclusion. The results showed that the transfection efficacy was increased with the increases in ultrasound output power and the ideal trans- fection efficacy was achieved in HepG2 cells irradiated by ultrasound at 0.8 W/cm2 for 30 s. The transfection efficacy in ulstrasound+P85 group was three times higher than in single ultrasound group [(17.63±1.07)% vs (5.57±0.56)%, P<0.051. The cell viability was about 81% and 62% in ultrasound group and ultrasound+P85 group respectively. It was concluded that ultrasound in combination with P85 could mediate the gene transfection of HepG2 cells, ideal transfection efficacy was achieved by ultrasound irradiation at 0.8 W/cm2 for 30 s, and P85 could somewhat increase the damage to cells caused by ultrasound.
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Phosphatidylinositol (PI) 3-kinase plays an important role in transducing the signals of various growth factor receptors. However, the regulatory mechanism of PI3-kinase activity by these growth factor receptors is not completely understood. Therefore, we attempted to clarify the regulatory mechanism of PI3-kinase using insulin and 3T3 L1 fibroblasts. Our results showed that insulin stimulated PI3-kinase activity seven-fold and concomitantly phosphorylated a p85 subunit at the tyrosine residue. However, this tyrosine phosphorylation was not significant in the activation of PI3-kinase as the PI3-kinase pulled down by the overexpressed GST-p85 fusion protein showed as high an activity as the immunoprecipitated one. The p110 subunit was phosphorylated at both serine and tyrosine residues without insulin treatment. Since the phosphorylation state was not changed by insulin. The results suggested that phosphorylation of the p110 subunit does not control PI3-kinase activity. Finally, it was shown that the insulin receptor substrate-1 (IRS-1) binding to PI3-kinase was not sufficient for full activation because the amount of IRS-1 pulled down by the GST-p85 fusion protein reached almost maximum, after incubation with insulin-treated cell lysates for 20 min, whereas PI3-kinase activity reached its maximum only after incubation for 5 h. All results suggest that the phosphorylation of p85 subunit at tyrosine residues and phosphorylation of p110 subunit at tyrosine or serine residues are not functionally significant in the regulation of PI3-kinase activity. They also suggest that P13-kinase is needed to bind to other protein(s) as well as the insulin receptor substrate-1 for full activation.