Curcumin Inhibits Viability of Clear Cell Renal Cell Carcinoma by Down-Regulating ADAMTS18 Gene Methylation though NF-κ B and AKT Signaling Pathway

Abstract

Objective: To investigate the effect of curcumin on viability of clear cell renal cell carcinoma (ccRCC) and analyze its possible mechanism.

Methods: In cell lines of A498 and 786-O, the effects of curcumin (1.25, 2.5, 5 and 10 μ mol/L) on the viability of ccRCC were analyzed at 24, 48 and 72 h by MTT assay. The protein expression levels of ADAMTS18 gene, p65, phosphorylation p65 (pp65), AKT, phosphorylation AKT (pAKT) and matrix metallopeptidase 2 (MMP-2) before and after curcumin (10 μ mol/L) treatment were examined by Western blotting. Real-time PCR and methylation specific PCR (MSP) were applied to analyze the expression and methylation level of ADAMTS18 gene before and after curcumin treatment (10 μ mol/L).

Results: Curcumin significantly inhibited the viability of A498 and 786-O cell lines in a dose- and time-dependent manner (P<0.01). Up-regulation of ADAMTS18 gene expression with down-regulation of ADAMTS18 gene methylation was reflected after curcumin treatment, accompanied by down-regulation of nuclear factor κ B (NF-κ kB) related protein (p65 and pp65), AKT related protein (AKT and pAKT), and NF-κ B/AKT common related protein MMP-2. With ADAMTS18 gene overexpressed, the expression levels of p65, AKT and MMP2 were downregulated, of which were conversely up-regulated in silenced ADAMTS18 (sh-ADAMTS18). The expression of pp65, pAKT and MMP2 in sh-ADAMTS18 was down-regulated after being treated with PDTC (NF-κ B inhibitor) and LY294002 (AKT inhibitor).

Conclusions: Curcumin could inhibit the viability of ccRCC by down-regulating ADAMTS18 gene methylation though NF-κ B and AKT signaling pathway.

Keywords: ADAMTS18 gene; clear cell renal cell carcinoma; curcumin; methylation; signaling pathway.