Label-free quantitative proteomic study of RUNX3 regulating Herceptin resistance in gastric cancer cells / 药学学报

Resistance of tumor cells is a complex biological process involving multiple mechanisms and factors, in which anti-apoptosis is the most important cause of drug resistance. Previous studies have shown that the DNA binding activity of Runt related transcription factor 3 (RUNX3) increased prominently in Herceptin resistant gastric cancer cells (NCI N87R) while the relevance of which to drug resistance has not yet been confirmed. In this study, we employed CRISPR/Cas9 to establish RUNX3 knock-out cell line (△RUNX3/NCI N87R) to investigate the functions of RUNX3 in Herceptin resistance of NCI N87R cells and its potential mechanisms. We investigated proteomics profiling of △RUNX3/NCI N87R cells based on label free quantitative proteomics. Differentially expressed proteins were screened out according to fold change and significance level between △RUNX3/NCI N87R and NCI N87R cells. Pathway enrichment analysis was done using GeneAnalytics database, and gene ontology analysis was conducted by DAVID Bioinformatics Resources database. Protein-protein interaction networks were constructed based on STRING database. The results showed that △RUNX3/NCI N87R cells increased the sensitivity to Herceptin. Proteomic data demonstrated that the expression of 577 genes changed significantly in △RUNX3/NCI N87R cells, among which 191 genes were up-regulated while 386 ones down-regulated comparing with NCI N87R cells. Pathway analysis showed that autophagy, cell cycle, apoptosis, mitochondrial fatty acid β oxidation, neurogenic locus notch homolog protein 1 (NOTCH1), mammalian target of rapamycin (mTOR), Hedgehog and DNA damage response pathways exhibited notable changes based on pathway enrichment ratio and significance level (P < 0.05). These results indicated that RUNX3 knock-out altered multiple signaling pathways of NCI N87R cells. Western blotting manifested that the expression of autophagy regulatory molecules autophagy-related protein (ATG) 13, 7 and BECN1 increased remarkably while cell cycle molecules serine/threonine-protein kinase Chk2 (CHEK2) and apoptosis regulator Bcl-2 (BCL2) decreased prominently in △RUNX3/NCI N87R cells. The p-AKT expression decreased significantly in △RUNX3/NCI N87R cells compared with NCI N87R cells (P < 0.01) and was suppressed by Herceptin. These results indicated that RUNX3 knock-out altered cell cycle, increased inhibition to p-AKT by Herceptin, promoted autophagy and induced cell apoptosis of NCI N87R cells. These results suggested that RUNX3 may be a potential therapeutic target for reversing or reducing Herceptin resistance in gastric cancer cells.

Curcumin inhibits proliferation,migration and invasion of gastric cancer cells via Wnt3a/β-catenin/EMT signaling pathway / 中国中药杂志

The aim of this paper was to investigate the effects of curcumin on the proliferation,migration,invasion and apoptosis of human gastric cancer cells and to explore the potential mechanisms. SGC7901,MKN45 and NCI N87 cells lines were cultured under different concentrations of curcumin( 2. 5,5,10,20,40,80 and 160 μmol·L~(-1)) at different time points( 12,24,48 and 72 h),and the effect of curcumin on cell proliferation was detected by CCK-8 assay. The migration and invasiveness of cells were determined by wound healing and Transwell assays,the apoptosis rate was assessed by flow cytometry,the expression of N-cadherin,E-cadherin,snail1,Wnt3 a,p-β-catenin,p-LRP6,Bcl-2 and Bax were detected by Western blot,and the enzymatic activity of caspase-3,caspase-8 and caspase-9 was evaluated via caspase kit. RESULTS:: indicated that the proliferation of MKN45 cells was significantly inhibited by curcumin in a dose-and time-dependent manner( IC50= 21. 93 μmol·L~(-1)). Moreover,curcumin could inhibit the migration and invasion of MKN45 cells,downregulate the expression of N-cadherin,snail1,Wnt3 a,p-β-catenin,p-LRP6 and Bcl-2,and upregulate the expression of E-cadherin and Bax,it could increase the activity of caspase-3,caspase-8,caspase-9 and induce apoptosis as well. The potential mechanism is through inhibiting the Wnt3 a/β-catenin/EMT pathway,regulating Bcl-2 signaling and caspase pathway,which might provide new potential strategies for gastric cancer treatment.

Mechanisms of curcumin to reverse herceptin resistance in gastric cancer cells / 药学学报

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.