| Objective: Sulforaphane (SFN) is a kind of anticarcinogen , which is mainly isolated from various cruciferous vegetables. Here we evaluate the effects of SFN on the proliferation and apoptosis of gastric adenocarcinoma cells (SGC7901) in vitro, and investigate the molecular mechanism, in order to provide the experimental basis for the application of this new phytochemical in Multimodal treatment of gastric cancer.Methods: 1. The gastric adenocarcinoma cell line SGC7901 cells were incubated in vitro, and MTT colorimetric assay was used to determine cells proliferation inhibition of SGC7901 cells after SFN intervention. 2. Invert phase-contrast and transmission electron microscopy were used to observe the morphological variations of apoptotic cells. 3. Flow cytometric analysis was used to detecte the percentage of apoptotic cells, mitochondiral transmembrane potential (△Ψm) and the cytosolic reactive oxygen species (ROS) level after SFN intervention. And immunocytochemical staining was used to detecte the expression of apoptosis-associated proteins Bax, Bcl-2, Bcl-X/L and Fas. 4. Flow cytometric analysis was used to detecte cell cycle, and RT-PCR was used to examine the mRNA expression of P21 gene .Results: 1. SFN at a concentration of 6.25～200μM inhibited the proliferation of SGC7901 cells in vitro in an obvious dose- and time-dependent manner. SFN inhibited the proliferation of SGC7901 cells with IC50 values 61.13μM, 43.74μM and 33.21μM following 24h, 48h and 72h treatments, respectively. 2. After cells were treated with SFN, typical apoptosis morphology changes of SGC7901 cells including condensation of cells and nuclear chromatin, disintegration of nuclear chromatin, aggregation and margination of apoptotic nuclear chromatin, cytoplasm condensation, and irregular chromatin masses were observed under transmission electron microscope. 3.(1) Flow cytometry analysis revealed significantly increases in apoptotic cells after treatment with SFN in a dose-dependent manner. The early apoptosis rates of SGC7901 cells were 5.13±0.34%, 8.37±0.67%, 12.02±0.56% and 24.89±0.37%, when treated with SFN 6.25μM, 12.5μM, 25μM and 50μM, respectively, compared with 2.74±0.31% in control group ( p<0.01 ) . (2) After treatment with 6.25～50μM SFN for 24h, the levels of mitochondiral transmembrane potential reduced significantly compared with control group(p<0.01). (3) The cytosolic ROS leves of SGC7901 cells increased in different degrees after exposure to 6.25～50μM SFN for 24h compared with control group. After treatment with 25μM SFN for 24h , expression of Bax and Fas protein in SFN experiment group increased significantly, while the expression of Bcl-X/L protein and Bcl-2/Bax decreased as compared with control group . When time was continued and it was strengthened significantly. 4. Flow cytometry analysis indicated a pronounced increase in the G0/G1 phase and an obvious decrease in the S phase after treated with 6.25～25μM SFN compared with control group. After treatment with 25μM SFN for 24h, the expression of P21 mRNA increased in a dose-dependent manner.Conclusion:1. SFN could inhibit the proliferation of SGC7901 cells in an dose- and time-dependent manner. 2.SFN could induce the early apoptosis of SGC7901 cells. ROS was shown to be active in the SFN induced mitochondrial apoptotic pathway, which possibly achieved by the decreasing of Bcl-X/L and activating of Bax. The increased expression of Fas protein in SFN treated group showed the death receptor pathway played a role. 3. SFN could cause arrest of SGC7901 cells at G0/G1 Phase. Effect of SFN on cells at G0/G1 Phase may be attributed to the up-regulation of P21 gene. 4. SFN is expected to be a promising drug against gastric cancer.
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