Published online Aug 18, 2016. doi: 10.4254/wjh.v8.i23.985
Peer-review started: April 8, 2016
First decision: May 23, 2016
Revised: May 25, 2016
Accepted: June 14, 2016
Article in press: June 16, 2016
Published online: August 18, 2016
AIM: To interfere with the activation of nuclear factor-κB (NF-κB) with metformin and explore its effect in reversing multidrug resistance (MDR) of hepatocellular carcinoma (HCC) cells.
METHODS: Expression of P-glycoprotein (P-gp) and NF-κB in human HepG2 or HepG2/adriamycin (ADM) cells treated with pCMV-NF-κB-small interference RNA (siRNA) with or without metformin, was analyzed by Western blot or fluorescence quantitative PCR. Cell viability was tested by CCK-8 assay. Cell cycle and apoptosis were measured by flow cytometry and Annexin-V-PE/7-AnnexinV apoptosis detection double staining assay, respectively.
RESULTS: P-gp overexpression in HepG2 and HepG2/ADM cells was closely related to mdr1 mRNA (3.310 ± 0.154) and NF-κB mRNA (2.580 ± 0.040) expression. NF-κB gene transcription was inhibited by specific siRNA with significant down-regulation of P-gp and enhanced HCC cell chemosensitivity to doxorubicin. After pretreatment with metformin, HepG2/ADM cells were sensitized to doxorubicin and P-gp was decreased through the NF-κB signaling pathway. The synergistic effect of metformin and NF-κB siRNA were found in HepG2/ADM cells with regard to proliferation inhibition, cell cycle arrest and inducing cell apoptosis.
CONCLUSION: Metformin via silencing NF-κB signaling could effectively reverse MDR of HCC cells by down-regulating MDR1/P-gp expression.
Core tip: Metformin might target AMP-activated protein kinase mammalian target of rapamycin pathway, suppress hypoxiainducible factor-1α and transcriptionally down-regulate P-glycoprotein (P-gp) and multidrug resistance (MDR)-associated protein 1, suggesting that metformin may reverse MDR by targeting the AMP-activated protein kinase/mammalian target of rapamycin/hypoxia-inducible factor-1α/P-gp and MDR-associated protein 1 pathways. In the present study, HepG2/ADM cells pretreated with metformin were sensitized to doxorubicin and P-gp was decreased through the nuclear factor-κB (NF-κB) signaling pathway. The synergistic effects were found in the cells with regard to proliferation inhibition, cell cycle arrest and inducing apoptosis, and inhibiting P-gp expression via the NF-κB signaling pathway effectively reversed MDR by down-regulating MDR1/P-gp expression.