Mechanisms of curcumin to reverse herceptin resistance in gastric cancer cells

This study is aimed to investigate the potential mechanisms of herceptin-acquired resistance and curcumin to reverse resistance in NCI N87/R gastric cancer cells. Western blot was used to evaluate the effect of curcumin on the expression of IκBα, NF-κBp65, HER-2, caspase-3, Bcl-2 and Bax in herceptin resistant cells; Annexin V-FITC/PI was exploited to analyze the effect of curcumin on cell apoptosis; Caspase kit was used to evaluate the effect of curcumin on the enzymatic activity of caspase-3, 8 and 9. The results showed a low expression of IκBα in the cytoplasm and a high expression of NF-κBp65 in the nucleus of NCI N87/R cells. Correspondingly, inhibition of NF-κB pathway by EVP4593, a specific NF-κB inhibitor, preferentially reduced cell viability of NCI N87/R cells, indicating the activation of NF-κB pathway in NCI N87/R cells. Curcumin preferentially reduced cell proliferation and inhibited NF-κB signaling pathway of NCI N87/R cells, downregulated the expression of HER-2 and Bcl-2, upregulated the expression of Bax, increased the activity of caspase-3, 8 and 9. Taken together, our study demonstrates the correlation between herceptin resistance acquirement of NCI N87 cells and the activation of NF-κB pathway. Moreover, curcumin reverses herceptin resistance of NCI N87 cells possibly by inhibiting NF-κB pathway and inducing cell apoptosis.