Yubo Xie

Overexpression of E2F1 in human gastric carcinoma is involved in anti-cancer drug resistance.

BackgroundRoutine chemotherapy often cannot achieve good therapeutic effects because of multidrug resistance (MDR). MDR is frequently caused by the elevated expression of the MDR1 gene encoding P-glycoprotein (P-gp). E2F1 is a frequently overexpressed protein in human tumor cells that increases the activity of the MDR1 promoter, resulting in higher P-gp levels. The upregulation of P-gp might contribute to the survival of tumor cells during chemotherapy. E2F1 confers anticancer drug resistance; however, we speculate whether E2F1 affects MDR through other pathways. This study investigated the possible involvement of E2F1 in anticancer drug resistance of gastric carcinoma in vitro and in vivo.MethodsA cisplatin-resistant SGC7901/DDP gastric cancer cell line with stable overexpression of E2F1 was established. Protein expression levels of E2F1, MDR1, MRP, TAp73, GAX, ZEB1, and ZEB2 were detected by western blotting. The influence of overexpression of E2F1 on anticancer drug resistance was assessed by measuring IC50 of SGC7901/DDP cells to cisplatin, doxorubicin, and 5-fluorouracil, as well as the rate of doxorubicin efflux, apoptosis, and cell cycle progression detected by flow cytometry. We determined the in vivo effects of E2F1-overexpression on tumor size in nude mice, and apoptotic cells in tumor tissues were detected by deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and hematoxylin and eosin staining.ResultsThe SGC7901/DDP gastric cancer cell line stably overexpressing E2F1 exhibited significantly inhibited sensitivity to cisplatin, doxorubicin, and 5-fluorouracil. Flow cytometry confirmed that the percentage of apoptotic cells decreased after E2F1 upregulation, and that upregulation of E2F1 potentiated S phase arrest of the cell cycle. Furthermore, upregulation of E2F1 significantly decreased intracellular accumulation of doxorubicin. Western blot revealed that E2F1 upregulation suppressed expression of GAX, and increased the expression of MDR1, MRP, ZEB1, TAp73, and ZEB2.ConclusionsOverexpression of E2F1 promotes the development of MDR in gastric carcinoma, suggesting that E2F1 may represent an efficacious target for gastric cancer therapy.

Exogenous morphine inhibits human gastric cancer MGC- 803 cell growth by cell cycle arrest and apoptosis induction.

Morphine is not only an analgesic treating pain for patients with cancer but also a potential anticancer drug inhibiting tumor growth and proliferation. To gain better insight into the involvement of morphine in the biological characteristics of gastric cancer, we investigated effects on progression of gastric carcinoma cells and the expression of some apoptosis-related genes including caspase-9, caspase-3, survivin and NF-κB using the MGC-803 human gastric cancer cell line. The viability of cells was assessed by MTT assay, proliferation by colony formation assay, cell cycle progression and apoptosis by flow cytometry and ultrastructural alteration by transmission electron microscopy. The influences of morphine on caspase-9, caspase-3, survivin and NF-κB were evaluated by semi-quantitative RT-PCR and Western blot. Our data showed that morphine could significantly inhibit cell growth and proliferation and cause cell cycle arrest in the G2/M phase. MGC-803 cells which were incubated with morphine also had a higher apoptotic rate than control cells. Morphine also led to morphological changes of gastric cancer cells. The mechanism of morphine inhibiting gastric cancer progression in vitro might be associated with activation of caspase-9 and caspase-3 and inhibition of survivin and NF-κB.

MiR-1284 modulates multidrug resistance of gastric cancer cells by targeting EIF4A1.

Routine chemotherapy as an important treatment mode often can not be effective because of multidrug resistance (MDR). MicroRNA (miRNA) modulates the expression of a great number of genes, including MDR. In this study, the expression of miR-1284 was reduced in gastric cancer (GC) tissue specimens with metastasis and in vincristine-resistant (VCR) GC SGC7901 cells (SGC-7901/VCR) compared to that in the controls. Recombinant lentiviral vectors with miR-1284 led to the overexpression of miR-1284 mRNA and reversed the chemoresistance of SGC7901/VCR cells, promoted cell cycle arrested at the G0/G1 phase, accelerated drug-induced apoptosis, and decreased migration and invasiveness of SGC-7901/VCR. In addition, the overexpression of miR-1284 sensitized tumors to chemotherapy in vivo. Our data provide combined evidence that miR-1284 can heighten the expression of MYC and reduce the expression of JUN, MMP12, and EIF4A1 that was the direct target. In conclusion, miR-1284 can function as a new regulator to reduce GC MDR cells by targeting EIF4A1.

Reversal of Multidrug Resistance in Gastric Cancer Cells by E2F‐1 Downregulation In Vitro and In Vivo

Transcription Factor E2F‐1 plays a critical role in cell cycle regulation and other biological processes in cells. However whether or not it is involved in the multi‐drug resistance (MDR) process of gastric cancer has not been fully elucidated yet. To explore the role of E2F‐1 in the MDR process of gastric cancer in vitro and in vivo, a cisplatin‐resistant gastric cancer cell line with stable downregulation of E2F‐1 was established. E2F‐1 shRNA led to downregulation of endogenous E2F‐1 mRNA and protein. It significantly promoted the sensitivity of SGC7901/DDP cells to cisplatin, doxorubicin, and fluorouracil. Flow cytometry confirmed that the percentage of apoptotic cells increased after E2F‐1 downregulation. This notion was further supported by the observation that downregulation of E2F‐1 blocked entry into the S‐phase of the cell cycle. Furthermore, downregulation of E2F‐1 significantly increased intracellular accumulation of doxorubicin. In addition, we determined the in vivo effects of E2F‐1 small interfering RNA (shRNA) on tumor size, and apoptotic cells in tumor tissues were detected by deoxynucleotidyl transferase‐mediated dUTP‐biotin nick end labeling and hematoxylin and eosin staining. In molecular studies, semiquantitative RT‐PCR and western blotting revealed that E2F‐1 downregulation could inhibit expression of MDR1, MRP, Bcl‐2/Bax, c‐Myc, Skp2, Survivin, and Cyclin D1. In conclusion: E2F‐1 may be involved in regulating multiple signaling pathways in reversing MDR, suggesting that E2F‐1 may represent a novel target for gastric cancer therapy. J. Cell. Biochem. 115: 34–41, 2014.

Fentanyl inhibits progression of human gastric cancer MGC-803 cells by NF-kappaB downregulation and PTEN upregulation in vitro.

Fentanyl is used as an analgesic to treat pain in a variety of patients with cancer. Moreover, fentanyl may affect tumor growth in many cell lines. To gain better insight into the interaction between fentanyl and tumor, we investigated the effects of fentanyl on the growth of gastric carcinoma cells and the expression of some apoptosis-related genes including NF-kappaB and PTEN. A human gastric cancer cell line MGC-803 was used. The viability and proliferation of gastric cancer MGC-803 cells were detected by MTT assay and colony formation assay. The cell cycle progression and apoptosis were assessed by flow cytometry and the ultrastructure of cells was examined with transmission electron microscope. The migration of cells was investigated by wound healing assay. The expression of NF-kappaB and PTEN was evaluated by semiquantitative RT-PCR and Western blot. Our data showed that fentanyl could inhibit cell growth and proliferation and made cell cycle arrest at G2/M phase. Compared with control cells, MGC-803 cells that were incubated with fentanyl also had a higher apoptotic rate. Fentanyl could lead to morphological changes of gastric cancer cells and reduce the motility of MGC-803 cells. Moreover, fentanyl could downregulate NF-kappaB and upregulate PTEN, which might be the mechanism of fentanyl inhibiting gastric cancer progression in vitro.

Transcription factor E2F-1 is upregulated in human gastric cancer tissues and its overexpression suppresses gastric tumor cell proliferation

The E2F family members play a critical role in cell cycle regulation and other biological processes in the cell. To better understand the involvement of E2F-1 in the development and progression of gastric tumors, we investigated the mutation and expression of E2F-1 in human gastric cancer tissues and the effect of E2F-1 overexpression on the proliferation of gastric carcinoma cells. In this study, 80 pairs of gastric cancer specimens and paratumor tissues from different patients and 40 stomach mucosa specimens from healthy individuals were examined. PCR-SSCP analysis demonstrated that mutations were not detected in any of the gastric cancer and normal tissue specimens. In addition, the results of an immunohistochemistry assay revealed higher expression rates of E2F-1 (P < 0.01) in gastric cancer tissues (72.5%) than in paratumor tissues (30.0%) of the same individuals and stomach mucosa from healthy individuals (22.5%). However, no correlation was observed between the E2F-1 levels and patients’ clinical features, such as sex, age, histological types, lymph node metastasis, and clinical stages (P >0.05). Finally, the influence of E2F-1 overexpression on the growth of human gastric carcinoma MKN-45 cells in vitro was assessed by measuring colony formation, cell survival, and cell cycle progression. Our data clearly showed that cell growth and proliferation were significantly inhibited in MKN-45 tumor cells transfected with the expression vector encoding E2F-1 in comparison with nontransfected cells or cells transfected with empty vector. These findings suggest that E2F-1, a stable and conservative gene during the oncogenesis and progression of stomach cancers, may potentially serve as a biomarker for clinical diagnosis of gastric carcinomas and as a target for the development of novel therapeutic interventions to treat this disease.

Propofol inhibits proliferation and induces neuroapoptosis of hippocampal neurons in vitro via downregulation of NF-κB p65 and Bcl-2 and upregulation of caspase-3.

Propofol is widely used in paediatric anaesthesia and intensive care unit because of its essentially short‐acting anaesthetic effect. Recent data have shown that propofol induced neurotoxicity in developing brain. However, the mechanisms are not extremely clear. To gain a better insight into the toxic effects of propofol on hippocampal neurons, we treated cells at the days in vitro 7 (DIV 7), which were prepared from Sprague–Dawley embryos at the 18th day of gestation, with propofol (0.1–1000 μM) for 3 h. A significant decrease in neuronal proliferation and a remarkable increase in neuroapoptosis were observed in DIV 7 hippocampal neurons as measured by 3‐(4,5‐dimethylthiazole‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay and apoptosis assay respectively. Moreover, propofol treatment decreased the nuclear factor kappaB (NF‐κB) p65 expression, which was accompanied by a reduction in B‐cell lymphoma 2 (Bcl‐2) mRNA and protein levels, increased caspase‐3 mRNA and activation of caspase‐3 protein. These results indicated that downregulation of NF‐κB p65 and Bcl‐2 were involved in the potential mechanisms of propofol‐induced neurotoxicity. This likely led to the caspase‐3 activation, triggered apoptosis and inhibited the neuronal growth and proliferation that we have observed in our in vitro systems. Copyright

siRNA targeting of Cdx2 inhibits growth of human gastric cancer MGC-803 cells

AIM To investigate the effects of small interference RNA (siRNA) targeting of Cdx2 on human gastric cancer MGC-803 cells in vitro and in vivo. METHODS The recombinant pSilencer 4.1-Cdx2 siRNA plasmids were constructed and transfected into gastric cancer MGC-803 cells in vitro. The stable transfectants were selected. The effects of Cdx2 siRNA on growth, proliferation, cell cycle, apoptosis, migration and invasiveness of human gastric cancer MGC-803 cells were evaluated and the expression of phosphatase and tensin homolog (PTEN), caspase-9 and caspase-3 was observed in vitro by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting analysis. We also investigated the effect of Cdx2 siRNA on growth of MGC-803 cells in nude mice in vivo. RESULTS Cdx2 siRNA led to inhibition of endogenous Cdx2 mRNA and protein expression as determined by RT-PCR and Western blotting analysis. Cdx2 siRNA significantly inhibited cell growth and proliferation, blocked entry into the S-phase of the cell cycle, induced cell apoptosis, and reduced the motility and invasion of MGC-803 cells. Cdx2 siRNA also increased PTEN expression, and activated caspase-9 and caspase-3 in MGC-803 cells in vitro . In addition, siRNA targeting of Cdx2 inhibited the growth of MGC-803 cells and promoted tumor cell apoptosis in vivo in nude mice tumor models. CONCLUSION Cdx2 was involved in regulating pro-gression of human gastric cancer cells MGC-803. Manipulation of Cdx2 expression may be a potential therapeutic strategy for gastric cancer.

Overexpression of E2F-1 inhibits progression of gastric cancer in vitro.

E2F‐1 plays a critical role in cell cycle regulation and other biological processes in cells. E2F‐1 mediates apoptosis and suppresses tumorigenesis in many tissue types, but there are few data available on E2F‐1 expression and its relationship to tumor kinetics in gastric cancer. To gain better insight into the involvement of E2F‐1 in the biological characteristics of gastric tumors, we investigated the effect of E2F‐1 overexpression on the progression of gastric carcinoma cells. A gastric cancer cell line stably overexpressing E2F‐1 (MGC‐803/E2F‐1) was established. The influence of E2F‐1 overexpression on in vitro cell growth was assessed by measuring cell survival, colony formation, and cell cycle progression. The results clearly show that overexpression of E2F‐1 significantly inhibits cell growth and proliferation, blocking entry into the S‐phase of the cell cycle. MGC‐803/E2F‐1 cells also had a higher apoptotic rate than control cells. In addition, E2F‐1 reduced the motility and invasion of gastric cancer cells.

Reversal of multidrug resistance in gastric cancer cells by CDX2 downregulation.

AIM To explore the role of CDX2 in the multi-drug resistance (MDR) process of gastric cancer in vitro and in vivo. METHODS A cisplatin-resistant gastric cancer cell line with stable downregulation of CDX2 was established. mRNA and protein expression levels of CDX2, survivin, cyclin D1, and c-Myc were detected by western blotting and semi-quantitative reverse-transcriptase polymerase chain reaction (RT-PCR). The influence of downregulation of CDX2 on MDR was assessed by measuring IC50 of SGC7901/DDP cells to cisplatin, doxorubicin, and 5-fluorouracil, rate of doxorubicin efflux, apoptosis, and cell cycle progression detected by flow cytometry. In addition, we determined the in vivo effects of CDX2 small interfering RNA (siRNA) on tumor size, and apoptotic cells in tumor tissues were detected by deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and hematoxylin and eosin staining. RESULTS CDX2 siRNA led to downregulation of endogenous CDX2 mRNA (0.31 ± 0.05 vs 1.10 ± 0.51, 0.31 ± 0.05 vs 1.05 ± 0.21, P = 0.003) and protein (0.12 ± 0.08 vs 0.51 ± 0.07, 0.12 ± 0.08 vs 0.55 ± 0.16, P = 2.57 × 10(-4)) expression. It significantly promoted the sensitivity of SGC7901/DDP cells to cisplatin (0.12 ± 0.05 vs 0.33 ± 0.08, 0.12 ± 0.05 vs 0.39 ± 0.15, P = 0.001), doxorubicin (0.52 ± 0.13 vs 4.11 ± 1.25, 0.52 ± 0.13 vs 4.05 ± 1.44, P = 2.81 × 10(-4)), and 5-fluorouracil (0.82 ± 0.13 vs 2.81 ± 0.51, 0.82 ± 0.13 vs 3.28 ± 1.03, P = 1.71 × 10(-4)). Flow cytometry confirmed that the percentage of apoptotic cells increased after CDX2 downregulation (32.15% ± 2.15% vs 17.63% ± 3.16%, 32.15% ± 2.15% vs 19.3% ± 2.25%, P = 1.73 × 10(-6)). This notion was further supported by the observation that downregulation of CDX2 blocked entry into the S-phase of the cell cycle (31.53% ± 3.78% vs 65.05% ± 7.25%, 31.53% ± 3.78% vs 62.27% ± 5.02%, P = 7.55 × 10(-7)). Furthermore, downregulation of CDX2 significantly increased intracellular accumulation of doxorubicin (0.21 ± 0.06 vs 0.41 ± 0.11, 0.21 ± 0.06 vs 0.40 ± 0.08, P = 0.003). In molecular studies, semiquantitative RT-PCR and western blotting revealed that CDX2 downregulation could inhibit expression of c-Myc, survivin and cyclin D1. CONCLUSION CDX2 may be involved in regulating multiple signaling pathways in reversing MDR, suggesting that CDX2 may represent a novel target for gastric cancer therapy.