The Effect Of Apoptosis Induced By Sulforaphane In Implanted Human Gastric Carcinoma SGC-7901Cells In Nude Mice

Objective: Sulforaphane (SFN), recognized as an potential anticarcinogen, wasmainly isolated from various cruciferous vegetables.In order to identify the molecularmechanisms of SFN-induced apoptosis in human gastric cancer cells SGC7901, theproliferation and apoptosis experiments were employed on nude mice.The phytochemistrySFN would provide new strategies for treatment of gastric cancer.Methods:20BALB/C nude mice in total,16-20g, male, six weeks old. Transplantedtumor models were established by injecting SGC7901cells into nude mice subcutaneously.When the tumors were up to about4mm in diameter, the mice were randomly divided into4groups and treated by SFN (control group, SFN1mg/kg, SFN3mg/kg, SFN10mg/kg).SFN wasinjected intraperitoneally respectively once every other day for six times totally.The tumorvolumes and tumor inhibition rates were measured continuously.16days later the nudemice were sacrificed by cervical dislocation and the tumor tissue were stripped andweighed rapidly. We observed the morphologic presentation under optical microscope afterHE staining. The SFN-induced apoptosis of SGC7901cells was evaluated under electronmicroscope and the apoptotic rates by TUNEL staining method. RT-PCR was used toexamine the mRNA expression of Bcl-2and Bax. Immunocytochemical staining was usedto detect the expression of apoptosis-associated proteins Bcl-2and Bax.Results:1.SFN at different concentrations (1-10mg/kg) inhibited proliferation ofSGC7901cells in vivo in an obvious dose-dependent manner. The inhibition rates by SFNin different groups (control group, SFN1mg/kg, SFN3mg/kg, SFN10mg/kg) were0,35.10%,56.98%,77.08%respectively.2.After SGC7901cells were treated with SFN,typical apoptotic morphology changes were observed under transmission electronmicroscope, including condensation of cells and nuclear chromatin, disintegration of nuclear chromatin, aggregation and margination of apoptotic nuclear chromatin, cytoplasmcondensation, and irregular chromatin masses.3. The positive expression rate of apoptosisby TUNEL staining method were11%,21%,29%,35%in different groups (control group,SFN1mg/kg, SFN3mg/kg, SFN10mg/kg) respectively (P<0.05).3. RT-PCR showed thatSFN decreased Bcl-2mRNA expression and increased Bax mRNA expression in SGC7901cells.4. Immunohistochemical examination showed that compared to the control group theexpression of Bax protein in the experiment groups increased significantly treated withSFN for two weeks, while the expression of Bcl-2protein decreased.Conclusion:1.SFN could inhibit the proliferation and tumor angiogenesis, as well asinduce the apoptosis of SGC7901cells.2.SFN was effective with dose dependence ininducing apoptosis of SGC7901cells. The mechanism of apoptosis induced by SFN maybe mediated by down-regulating Bcl-2expression and up-regulating Bax expression.3.SFN would be a promising drug against gastric cancer.