Ginsenoside Rg3 regulates CaM gene expression through PI3K/AKT signal system to promote apoptosis of gastric cancer BGC-823 cell / 中国肿瘤生物治疗杂志

@#Objective: To investigate Ginsenoside Rg3 interfering the expression of CaM through PI3K/AKT signaling pathway to affect the biological activity of gastric cancer BGC-823 cells. Methods: After the culture and passage of gastric cancer BGC-823 cells, Western blotting was used to detect the expression of p-AKT and CaM protein in gastric cancer BGC-823 cells treated with IGF-1 and/ or Rg3; The effect of IGF-1 and/or Rg3 on the proliferation of BGC-823 cells was detected by MTT assay; The effect of IGF-1 and/or Rg3 on the invasion of BGC-823 cells was detected by Transwell assay; Effect of IGF-1 and/or Rg3 on apoptosis of BGC-823 cells was detected by Flow Cytometry. Results: Western blotting results showed that the expression of p-AKT and CaM protein increased in BGC-823 cells with the prolongation of IGF-1 treatment (all P<0.05); Compared with the blank control group, Rg3 significantly inhibited the proliferation of BGC-823 cells, while IGF-1 and IGF-1+Rg3 significantly promoted the cell proliferation (all P<0.05); Compared with the blank control group, Rg3 significantly reduced the invasion of BGC-823 cells, while IGF-1 and IGF-1+Rg3 significantly promoted the invasion of BGC-823 cells (all P<0.05);Flow cytometry showed that compared with the blank control group, Rg3 significantly promoted the apoptosis of BGC-823 cells, while IGF-1 and IGF-1+Rg3 significantly inhibited the apoptosis of BGC-823 cells (all P< 0.05). Conclusion: Ginsenoside Rg3 inhibits the expression of CaM by blocking PI3K/AKT signaling pathway, thereby promoting the apoptosis of gastric cancer BGC-823 cells.

Silencing of Bmi-1 gene by RNA interference enhances sensitivity to doxorubicin in breast cancer cells.

The oncogene Bmi-1 is highly up-regulated in breast carcinoma and is found to be efficient in preventing apoptosis of the cancer cells. Doxorubicin is an important chemotherapeutic agent against breast carcinoma. However, the effective therapeutic response to doxorubicin is often associated with severe toxicity. The present study is targetted at developing a strategy to increase doxorubicin sensitivity to lower doses without compromising its efficacy. A stable cell line with a persistent silencing of Bmi-1 was established. MTT assay was performed to evaluate 50% inhibitory concentration (IC50) values of doxorubicin. Apoptosis was detected by FCM and the expression of related genes [phosphor-Akt (pAkt), totle-Akt (tAkt), Bcl-2 and Bax] was studied by Western blot. In vivo, the sensitivity of the tumor tissues against doxorubicin was evaluated by transplanted MCF-7 nude mice model and the apoptosis of tissue cells was detected by TUNEL assay. The expression of pAkt and Bcl-2 was down-regulated, whereas Bax was up-regulated in Bmi-1 silencing cells. The results obtained indicated that silencing of Bmi-1 can render MCF-7 cells more sensitive to doxorubicin which induced a significantly higher percentage of apoptosis cells in vitro and in vivo. All together these results clearly demonstrate that Bmi-1 siliencing combined treatment of doxorubicin might be a new strategy for biological treatment on breast cancer.

RNAi-mediated silencing of the Bmi-1 gene causes growth inhibition and enhances doxorubicin-induced apoptosis in MCF-7 cells

The oncogene Bmi-1 is a member of the Polycomb group gene family. Its expression is found to be greatly increased in a number of malignant tumors including breast cancer. This could suggest Bmi-1 as a potent therapeutic target. In this study, RNAi was introduced to down-regulate the expression of Bmi-1 in a highly malignant breast adenocarcinoma cell line, MCF-7. A thorough study of the biological behavior and chemosensitivity changes of the MCF-7 cells was carried out in context to the therapeutic potential of Bmi-1. The results obtained indicated that siRNA targeting of Bmi-1 could lead to an efficient and specific inhibition of endogenous Bmi-1 activity. The mRNA and protein expression of Bmi-1 were determined by RT-PCR and Western blot, respectively. Furthermore, silencing of Bmi-1 resulted in a drastic inhibition of the growth of MCF-7 cells as well as G1/S phase transition. The number of target cells was found to increase in phase G0/G1 and decrease in the S phase, but no increase in the basal level of apoptosis was noticed. On the other hand, a reduction in the expression of cyclin D1 and an increase in the expression of p21 were also noticed. Silencing of Bmi-1 made the MCF-7 cells more sensitive to the chemotherapeutic agent doxorubicin and induced a significantly higher percentage of apoptotic cells. Here, we report on a study regarding the RNAi-mediated silencing of the Bmi-1 gene in breast cancer.