Curcumin Inhibits MDA-MB-231Human Breast Cancer Cell Invasion Via Down Regulation Of Ngal Expression

Objective To investigate new molecular mechanisms underline theinhibitory effect of Curcumin on tumor cell invasion, we examined its role inthe regulation of NGAL expression, a newly identified gene associated withpromotion of tumor metastasis. Method Human breast cancer cell lineMDA-MB-231was used for this study. MDA-MB-231cells were treatedwith varying doses of Curcumin. For some experiments, cells were alsotreated with NF-κB specific inhibitor Bay-117082(20μmol/L) in order tocompare the inhibitory effect of NF-κB inactivation on MDA-MB-231cellfunction.The cytotoxic effect of Curcumin was measured by MTT assay.Cell invasiveness was assessed by the Matrigel Transwell invasion assay.Alterations in cell adhesive properties upon drug treatment were determinedby the cell adhesion assay. NGAL and MMP-9expression was examined byWestern blot and RT-PCR, respectively,IκBαand P-IκBαexpression wereexamined by Western blot. Effect of Curcumin and Bay-117082on activityof MMP-9were examined by zymography.Results While Curcumin doseand time-dependently inhibited MDA-MB-231cell growth, it exhibited no significant cytotoxic effect at24h post-treatment with doses less than15μM.Additionally, Curcumin significantly inhibited the invasive and adhesivecapabilities of MDA-MB-231cells and the maximal effect was observed at15μM(P<0.001).The effect of Bay-117082was same to Curcumin(15μM).Western blot analysis shows that while Curcumin had no effect on IκBαexpression, it does-dependently inhibited IκBαphosphorylation. Further, italso dose-dependently inhibited NGAL and MMP-9mRNA and proteinexpression.The inhibitory effect of Curcumin on NGAL,MMP-9and P-IκBαexpression was comparable to that of treatment with NF-κB specificinhibitor Bay-117082(P<0.05). Zymography showed activity of MMP-9was blocked by Curcumin in a dose-dependent fashion(P＜0.05). AndBay-117082inhibited activity of MMP-9was similar to the role ofCurcumin (15μM).Conclusion In this study, we show in vitro that theanti-neoplastic function of Curcumin could be achieved via inhibition of theinvasiveness of human breast cancer cells. We demonstrate for the first timethat at the non-cytotoxic doses, Curcimin treatment inhibited the expressionof NGAL, a newly identified effector gene of NF-κB signaling. Theobserved inhibitory effect of Curcumin on NGAL expression is likely alsothrough interference with NF-κB signaling. Therefore, we have identifiedNGAL as an intracellular gene target of Curcumin.