| Objective:Dially disulfide (DADS), which is a valuable anti-cancer drug candidate, possesses significant inhibitory effects on various tumor cells. In recent years, the role of LIMK1 in regulating carcinogenesis has been aroused extensive concern. LIMK1 plays an important role in regulating the division differentiation and invasion of tumor cells and is one of the key elements that leads to tumor cell proliferation, invasion and metastasis. The mechanisms of the anti-tumor function of DADS remain unclear. In recent study, we will investigate the effects of DADS on the expression of LIMK1 and the influence on its signaling pathway in MGC803 cells to elucidate the molecular mechanism of the inhibitory effects of DADS on the proliferation, invasion and metastasis of tumor cells.Methods: The proliferation of MGC803 cells was evaluted by MTT assay. The effects of DADS on cell migration and invasion were detected by Wound Healing assay and Transwell assay。The expression of LIMK1 in MGC803 cells was detected by immunohistochemistric assay. The mRNA and protein of Rac1, Rock1, Pak1, LIMK1 and cofilin1 in MGC803 cells were determined by RT-PCR and Western blot, respectively.Results:1. DADS inhibits proliferation, migration and invasion in gastric cancer cells.Human gastric cancer MGC803 cells exposed to DADS 30mg·L-1 for 24h,48h,72h,96 h had less absorbance value than control,which exhibited a time-dependent model (P<0.05),whereas DADS induced-growth inhibition rate enhanced from 11.3%,35.2%,50.7% to 60.6% assessed by MTT test(P<0.05) indicating that DADS had effects on the inhibition of cell proliferation in a time-dependent manner.Observe DADS on cell invasion and migration ability using Transwell and scratch experiments. Observe the healing results on 0 and 24 of MGC803 cells exposed to 10,20,30,40,50 mg ? L-1 DADS,respectively using scratch test, the results showed that the rate of the control group was significantly higher than treated one by DADS, indicating cell migration was inhibited in a dose - dependent manner (P <0.05). MGC803 cells were exposed to 10,20,30,40,50 mg ? L-1 DADS for 24 h,respectively, and 10 groups were selected randomly, Transwell experiments showed that, control group for 39.5±2.99, plus treated group were 35.8±3.74 , 34.1±2.02, 31.7±4.81, 17.2±3.08, 13.2±3.36, the number of treated group cells through Matrigel significantly lower than that in the control group in a dose-dependent manner (P <0.05).2. DADS down-regulates LIMK1 expression in gastric cancer cells. RT-PCRshowed that treated with 30 mg·L-1 DADS for 48h extenuates the expression of LIMIK1 mRNA in MGC803 cells. Western blot and immunohistochemistric assay demonstrated that exposed to 30 mg·L-1 DADS for 24h, 48h, 72h, 96 h, the expression of LIMK1 protein in MGC803 cells decreased in a time-dependent manner.3. DADS inhibits the activation of cofilin1, but not that of Destrin.RT-PCR and western blot showed that DADS did not affect the expression of cofilin1 in MGC803 cells. However, when MGC803 cells were exposed to DADS (30 mg·L-1) for 6, 12, 24, 48h, the level of cofilin1 phosphorylation was reduced, respectively. On the other hand, RT-PCR and Western blot showed that DADS (30 mg·L-1) did not affect the expression of Destrin.4. DADS inhibits the pathway of Rac1/Rock1/Pak1.RT-PCR showed that DADS (30 mg·L-1) for 48h inhibited the expression of Rac1, Rock1 and Pak1 mRNA in MGC803 cells, respectively. Western blot demonstrated that when MGC803 cells were exposed to DADS (30 mg·L-1) for 6, 12, 24, 48 h, the expression of Rac1, Rock1 and Pak1 protein in MGC803 cells was down-regulated, respectively.Conclusion:1. DADS inhibits the proliferation, migration and invasion of MGC803 cells.2. The inhibitory effects of DADS on the proliferation, migration and invasion in MGC803 cells involved, which leads to the inhibition of cofilin1 activation.3. The down-regulated LIMK1 of DADS is caused by the prevention of Rac1-Rock1/Pak1- LIMK1 pathway.
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