[Effects of Betulinic acid on apoptosis in human gastric cancer SGC-7901 cells].

Objective: To investigate the effects of betulinic acid on apoptosis of human gastric cancer SGC-7901 cells. Methods: The human gastric cancer SGC-7901cells were divided in to 4 groups, and each group was set with 3 replicates. The SGC-7901cells in control group were not treated with betulinic acid; the other 3 experimental groups were treated with betulinic acid at the concentrations of 10, 20 and 30 mg/L, respectively; each group was incubated in a 5% carbon dioxide incubator for 48 h. Laser confocal microscope was used to observe morphological changes of SGC-7901 cells; Flow cytometry was applied to determine apoptosis rate and mitochondrial membrane potential. The mRNA and protein levels of Bcl-2, Bax and Caspase-3 were also detected by qRT-PCR and western blot respectively. Results: Compared with the control group, SGC-7901 cells in the treated group at final concentrations of 10, 20 and 30 mg/L shrinked, appeared apoptosis body along with nuclear splitting. The percentage of cells in early and advanced period of apoptosis were markedly increased (P＜0.05 or P＜0.01), mitochondrial membrane potential was obviously reduced (P＜0.05 or P＜0.01). qRT-PCR and western blot analysis showed that the mRNA and protein expressions of Bax and Caspase-3 were increased significantly (P＜0.01), while the expressions of Bcl-2 were decreased significantly (P＜0.01). Conclusion: Within a certain range of concentrations, betulinic acid induces cell apoptosis by regulating the expression of Bcl-2, Bax and Caspase-3 in human gastric cancer.

[Effects of betulinic acid at different concentrations on autophagy of human gastric cancer MGC-803 cells].

Objective: In this study, human gastric cancer MGC-803 cells were treated with betulinic acid at different concentrations to investigate its effect on cell autophagy. Methods: The human gastric cancer MGC-803 cells were divided into 4 groups, each group was set with 3 replicate. The control group was not treated with betulinic acid, the other three groups were added with final concentration of 10,20,30 mg/L betulinic acid, respectively. Cells were treated with betulinic acid for 48 h,qRT-PCR was applied to detect the effect of betulinic acid on mRNA expressions of autophagy-related genes in human gastric cancer MGC-803 cells. Western blot was performed to determine the protein expressions of cell autophagy-related genes after drug treatment. Immunofluorescence was used to detect the localization and expression of LC3 protein in MGC-803 cells after drug treatment. Results: Compared with the control group,in the concentration range of 10~30 mg/L, the mRNA expression of LC3 and Beclin-1 in human gastric cancer MGC-803 cells treated with betulinic acid were increased significantly, the expressions of Beclin-1 and LC3-Ⅱ protein were also increased significantly, while the expression of LC3-Ⅰ protein was decreased significantly. Among them, betulinic acid at the concentration of 30 mg/L showed the best effects. In addition, betulinic acid induced the LC3 protein in MGC-803 cells to form spot aggregates in the cytoplasm. Conclusion: At the concentrations of 10~30 mg/L, betulinic acid can induce autophagy in human gastric cancer MGC-803 cells.

[Effect of betulinic acid on proliferation of human gastric cancer MGC-803 cell line].

Objective: To investigate the effect of betulinic acid on the proliferation of human gastric cancer MGC-803 cells in vitro. Methods: Human gastric cancer MGC-803 cells were divided into 4 groups, each with 3 multiple holes. Control cells add betulinic acid at a concentration of 0 µg /ml, and the other three experimental groups were added with final concentration of 10, 20, 30 µg/ml Betulinic acid respectively. Cells in each group were incubated in a 5% CO2 incubator for 48 hours, and the Giemsa staining method and trypan blue exclusion method were used to detect the effect of betulinic acid on the cell clone formation rate and growth inhibition rate; EdU method and flow cytometry were used to detect cell proliferation and cell cycle changes; qRT-PCR and Western blot were used to detect the expressions of cell cycle regulators CCNB1 and CCND1. Results: Compared with the control group, the clone formation rate of human gastric cancer MGC-803 cells was significantly reduced (P＜0.01), the growth inhibition rate was significantly increased, and the cell proliferation ability was significantly decreased (P＜0.01); with the increase of betulinic acid concentration in each experimental group the proportion of cells in the G1 phase was gradually decreased, and the number of cells in S phase was increased significantly (P＜0.01); the mRNA and protein expression levels of cell cycle regulators CCNB1 and CCND1 were decreased significantly, and the 30 µg/ml betulinic acid treatment group performed best. Conclusion: At a final concentration of 10～30 µg/ml, betulinic acid can reduce the proliferation of human gastric cancer MGC-803 cells, inhibit cell growth, and down-regulate the expression of CCNB1 and CCND1 to block human gastric cancer MGC-803 cells in the S phase.

[Toosendanin induces apoptosis of human gastric cancer MGC-803 cells and its mechanism].

Objective: To explore the apoptosis of human gastric cancer MGC-803 cells induced by toosendanin(TSN) and its mechanism. Methods: The human gastric cancer MGC-803 cells were divided into 5 groups, each group was set with 3 replicate. Fluorouracil (5-FU) and 0 nmol/L toosendanin (TSN) were used as positive control and negative control, respectively. The other three groups were treated with toosendanin at the final concentrations of 30, 50, and 70 nmol/L, respectively. After 48 h of treatment with toosendanin, the morphology of the cells were observed under laser confocal microscopy. Flow cytometry was used to detect the mitochondrial membrane potential, and enzyme-labeled assays were used to detect the activities of Caspase-3 and Caspase-9. The mRNA and protein levels of Bcl-2, Bax, Cyt c and APAF-1 were measured by qRT-PCR and Western blot. Results: Compared with the 0 nmol/L TSN group, after the human gastric cancer MGC-803 cells were treated with toosendanin at the concentrations of 30, 50, and 70 nmol/L for 48 h, the cell volume shrinkage, nucleus cleavage and chromatin morphological changes were observed under the microscope. The activities of Caspase-3 and Caspase-9 were increased significantly (P＜0.05), while the mitochondrial membrane potential was decreased significantly (P＜0.05). In addition, the mRNA and protein expression levels of Bax, Cyt c and APAF-1 were increased significantly (P＜0.05), while the mRNA and protein expression levels of Bcl-2 were decreased significantly (P＜0.05). Conclusion: Toosendanin up-regulates the expressions of Bax, Cyt c and APAF-1, down-regulates the expression of Bcl-2 gene, enhances the activities of caspase-3 and caspase-9, and induces the apoptosis of human gastric cancer MGC-803 cells.

[Effects of betulinic acid on apoptosis of human gastric cancer MGC-803 cells].

Objective: The effects of betulinic acid (BA) on apoptosis of human gastric cancer MGC-803 cells was investigated by using human gastric cancer MGC-803 cells as experimental materials, and the basis for its clinical application was provided. Methods: The human gastric cancer MGC-803 cells were divided into 4 groups,each group was set with 3 replicates.The control group was MGC-803 cells without being added betulinic acid; the other 3 groups of experimental groups were treated with betulinic acid at final concentrations of 10, 20 and 30 µg /ml respectively. Cells were treated with betulinic acid of different concentrations for 48 h. Laser confocal microscope was used to observe morphological changes of MGC-803. The activities of Caspase-3 and Caspase-9 were detected by an assay kit. Flow cytometry was applied to determine mitochondrial membrane potential. The mRNA and protein levels of Caspase-3, Caspase-9 and Cyt c were also detected by qRT-PCR and Western blot, respectively. Results: Compared with the control group, the activities of Caspase-3 and caspase-9 were increased(P＜0.01), while the mitochondrial membrane potential was decreased significantly(P＜0.01). The mRNA and protein expressions of Caspase-3, caspase-9 and Cyt c were up-regulated significantly(P＜0.01). Conclusion: In the final concentration range of 10 ~ 30 µg/ml, betulinic acid can induce apoptosis of human gastric cancer MGC-803 cells by regulating the expression of Caspase-3, Caspase-9 and Cyt c.

The α-Subunit of the Chloroplast ATP Synthase of Tomato Reinforces Resistance to Gray Mold and Broad-Spectrum Resistance in Transgenic Tobacco.

Chloroplast ATP synthase (cpATPase) is responsible for ATP production during photosynthesis. Our previous studies showed that the cpATPase CF1 α subunit (AtpA) is a key protein involved in Clonostachys rosea-induced resistance to the fungus Botrytis cinerea in tomato. Here, we show that expression of the tomato atpA gene was upregulated by B. cinerea and Clonostachys rosea. The tomato atpA gene was then isolated, and transgenic tobacco lines were obtained. Compared with untransformed plants, atpA-overexpressing tobacco showed increased resistance to B. cinerea, characterized by reduced disease incidence, defense-associated hypersensitive response-like reactions, balanced reactive oxygen species, alleviated damage to the chloroplast ultrastructure of leaf cells, elevated levels of ATP content and cpATPase activity, and enhanced expression of genes related to carbon metabolism, photosynthesis, and defense. Incremental Ca2+ efflux and steady H+ efflux were observed in transgenic tobacco after inoculation with B. cinerea. In addition, overexpression of atpA conferred enhanced tolerance to salinity and resistance to the fungus Cladosporium fulvum. Thus, AtpA is a key regulator that links signaling to cellular redox homeostasis, ATP biosynthesis, and gene expression of resistance traits to modulate immunity to pathogen infection and provides broad-spectrum resistance in plants in the process.

[Effect of betulinic acid on proliferation of human gastric cancer SGC-7901 cells].

Objective: Human gastric cancer SGC-7901 cells were treated with betulinic acid(BA)at the concentrations of 0, 10, 20, and 30 µg/ml, and treated with conventional chemotherapeutic drug 5-Fu as a positive control to explore its effect on cell proliferation. Trypan blue and GIEMSA staining method were used to investigate the effect of BA on cell growth inhibition and clone formation. EdU method and flow cytometry were used to explore the proliferation and cell cycle of SGC-7901 cells after treated with BA, respectively. qRT-PCR and Western blot were also applied to determine the mRNA and protein levels of cyclin D1 and cyclin B1. Results: The cell growth inhibition rate was increased after treated with different concentrations of BA in SGC-7901 cells(P＜0.05). After treated for 48 h, BA decreased the clone information and cell proliferation of SGC-7901 cells markedly in dose-and time-dependent manners (P＜0.01). Flow cytometry analysis showed that BA obviously increased the proportion of SGC-7901 cells in G1 phase but decreased the proportion of those in S phase. qRT-PCR and Western blot analysis showed that the mRNA and protein levels of cyclin D1 and cyclin B1 were significantly downregulated by BA at different concentrations(P＜0.01). Compared with the 5-Fu control group, when the concentration of BA was 20 µg/ml and 30 µg/ml, the cell proliferation ability was significantly decreased, the cell cycle was inhibited, and the expression of cyclin was reduced (all P＜0.05). Conclusion: The betulinic acid regulates the proliferation of SGC-7901 cells by inhibiting the expressions of cyclin D1 and cyclin B1, which leads to cell cycle arrest and proliferative inhibition.

Highly sensitive detection of protein with aptamer-based target-triggering two-stage amplification.

Highly sensitive detection of proteins is essential to biomedical research as well as clinical diagnosis. However, so far most detection methods rely on antibody-based assays and are usually laborious and time-consuming with poor sensitivity. Here, we develop a simple and sensitive method for the detection of a biomarker protein, platelet-derived growth factor BB (PDGF-BB), based on aptamer-based target-triggering two-stage amplification. With the involvement of an aptamer-based probe and an exponential amplification reaction (EXPAR) template, our method combines strand displacement amplification (SDA) and EXPAR, transforming the probe conformational change induced by target binding into two-stage amplification and distinct fluorescence signal. This detection method exhibits excellent specificity and high sensitivity with a detection limit of 9.04 × 10(-13) M and a detection range of more than 5 orders of magnitude, which is comparable with or even superior to most currently used approaches for PDGF-BB detection. Moreover, this detection method has significant advantages of isothermal conditions required, simple and rapid without multiple separation and washing steps, low-cost without the need of any labeled DNA probes. Furthermore, this method might be extended to sensitive detection of a variety of biomolecules whose aptamers undergo similar conformational changes.

Advancement and prospects of tumor gene therapy.

Gene therapy is one of the most attractive fields in tumor therapy. In past decades, significant progress has been achieved. Various approaches, such as viral and non-viral vectors and physical methods, have been developed to make gene delivery safer and more efficient. Several therapeutic strategies have evolved, including gene-based (tumor suppressor genes, suicide genes, antiangiogenic genes, cytokine and oxidative stress-based genes) and RNA-based (antisense oligonucleotides and RNA interference) approaches. In addition, immune response-based strategies (dendritic cell- and T cell-based therapy) are also under investigation in tumor gene therapy. This review highlights the progress and recent developments in gene delivery systems, therapeutic strategies, and possible clinical directions for gene therapy.

Reversal of MDR1 gene-dependent multidrug resistance in HL60/HT9 cells using short hairpin RNA expression vectors.

Multidrug resistance (MDR) is a serious obstacle to cancer chemotherapy. Overexpression of P-glycoprotein (P-gp), the MDR1 gene product, confers MDR to tumor cells. This study explored the possibility of reducing drug resistance by targeting the mdr1 gene using short hairpin RNA (shRNA). Two different shRNAs were designed and constructed in a pSilencer 2.1-U6 neo plasmid. The shRNA recombinant plasmids were transfected into HT9 leukemia cells. Real-time polymerase chain reaction and Western blotting were used to characterize the inhibited expression of MDR1 mRNA and P-gp, and the drug sensitivity of the transfected cells was assessed using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. The results indicated that the inhibition of P-gp expression by small interfering RNA selectively restored sensitivity to the drugs transported by P-gp. Evaluation of chemosensitivity showed 52.58% reversal by p2.1-shRNA1 and 73.07% reversal by p2.1-shRNA2 in drug resistance for harringtonine, and 84.87% reversal by p2.1-shRNA1 and 94.23% reversal by p2.1-shRNA2 in drug resistance for curcumin in the transfected cells. The results demonstrated the efficacy and selectivity of shRNA in reversing MDR in drug-resistant HT9 cells in vitro.