Silibinin promotes the apoptosis of gastric cancer BGC823 cells through caspase pathway.

PURPOSE: To investigate the effects of silibinin, a natural compound, on the proliferation and apoptosis of BGC-823 gastric cancer cell line and to figure out the relevant pathways. METHODS: BGC-823 gastric cancer cells were treated with silibinin at various concentrations (0,25,50,100,150 and 200µM). Zero µM was the control group and the other concentrations were defined as the experimental groups. The effects of silibinin on the proliferation of BGC-823 gastric cancer cells were explored through methylthiazolyldiphenyltetrazolium bromide (MTT). Silibinin's toxic effects were detected through determination of the concentration of lactic dehydrogenase (LDH). Flow cytometry was performed to explore the effects of silibinin on apoptosis of these cells. Western blotting was conducted to study the relevant pathways acting on the BGC-823 cells. RESULTS: MTT assay showed that with the increase in silibinin concentration and extension of exposure time, the inhibitory effect silibinin on cell proliferation was enhanced in an obvious time-dosage pattern. The results of LDH detection showed that the toxicity of silibinin to cells was enhanced in an obvious time-dosage pattern with the increase in drug concentration and extension of exposure time. Flow cytometry revealed that with the increase in drug concentration, gradual increase in the proportion of early and late of apoptotic cells took place, and the comparison between the experimental and the control group showed that the difference had statistical significance. Western blotting indicated that silibinin could upregulate the expression of mitochondrial apoptosis-associated proteins, and the difference in comparison with the control group had statistical significance. CONCLUSION: Silibinin can inhibit the proliferation of BGC- 823 gastric cancer cells, and such an inhibitory effect is time- and concentration-dependent. Additionally, silibinin can promote the apoptosis of BGC-823 gastric cancer cells, which may be realized through mitochondrial apoptosis.

Delimitation of the PSH1(t) gene for rice purple leaf sheath to a 23.5 kb DNA fragment.

Leaf sheath color plays an important role as a marker for rice genetic improvement. A recombinant inbred line (RIL) population consisting of 220 individuals was developed from a cross between an Oryza sativa subsp. indica variety, IRBB60, and an Oryza sativa subsp. japonica variety, 9407. Within the RIL population, a line, RI51, was found to have purple leaf sheath (PSH). To map the gene governing PSH, RI51 was crossed with 9407 green leaf sheath (GSH) to develop an F2 segregating population. The distribution of F2 plants with PSH and GSH fitted a segregation ratio of 3:1, indicating that the PSH was controlled by a major dominant gene. The gene locus for PSH, tentatively designated as PSH1(t), was identified by surveying two bulks made of the respective 40 individuals with PSH and GSH with SSR markers covering the entire rice genome. The survey indicated that the PSH1(t) region was located on chromosome 1. Further confirmation was made using a large random sample of 360 individuals from the same F2 population and the PSH1(t) locus was then mapped on chromosome 1 between SSR markers RM3475 and RM7202 with genetic distances of 2.0 and 1.1 cM, respectively. For fine mapping of PSH1(t), a large F(2:3) segregating population with 3300 individuals from the seven heterozygous F2 plants in the RM3475-RM7202 region was constructed. Analysis of recombinants in the PSH1(t) region anchored the gene locus to an interval of 23.5 kb flanked by the left marker L03 and the right marker L05. Sequence analysis of this fragment predicted six open reading frames encoding a putative trans-sialidase, a putative Plastidic ATP/ADP-transporter, and four unknown proteins. The detailed genetic and physical maps of the PSH1(t) locus will be very useful in molecular cloning of the PSH1(t) gene.