Background & objective: Diallyl disulfide (DADS) can inhibit the proliferation of various cancer cell lines in vitro, but little is known about its in vivo antitumor effect. This study was to investigate the inhibitory effect of DADS on the proliferation of human colon cancer cell line SW480 in nude mice.
Methods: After subcutaneous transplantation of SW480 cells in the back of nude mice, 5 mice received intraperitoneal injection of DADS (30 mg/kg), and 5 received intraperitoneal injection of normal saline as control. The body weight of nude mice and tumor growth were measured. The morphology of tumor was observed under optical microscope and electron microscope. The expression of proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry and morphometric quantitative analysis. Cell cycle distribution was analyzed by flow cytometry (FCM).
Results: The growth of transplanted tumor was inhibited markedly by DADS; the relative tumor growth rate (T/C%) was 49.85%. In DADS group, the cellular atypia and nucleus-cytoplasm ratio were decreased, intracytoplasm cellular organs were abundant, and retrograde alters and apoptotic bodies were manifested in some cells. The protein level of PCNA was significantly lower in DADS group than in control group (149.02+/-4.26 vs. 178.86+/-7.69, P<0.05). SW480 cells in DADS group were arrested in G2/M phase; the G2/M phase proportion was significantly higher in DADS group than in control group (38.6% vs. 18.8%, P<0.01).
Conclusion: DADS has significant inhibitory effect on the proliferation of human colon cancer SW480 cells in nude mice and can arrest cell cycle in G2/M phase.