Inhibition of p38 MAPK-dependent MutS homologue-2 (MSH2) expression by metformin enhances gefitinib-induced cytotoxicity in human squamous lung cancer cells
Journal
Lung Cancer
Journal Volume
82
Journal Issue
3
Pages
397-406
Date Issued
2013
Author(s)
Chiu H.-C.
Wo T.-Y.
Huang Y.-J.
Tseng S.-C.
Huang Y.-C.
Chen H.-J.
Syu J.-J.
Chen C.-Y.
Jian Y.-T.
Jian Y.-J.
Lin Y.-W.
Abstract
Objectives: Gefitinib, a quinazoline-derived tyrosine kinase inhibitor, has anti-tumor activity in vivo and in vitro. Human MutS homologue-2 (MSH2) plays a central role in promoting genetic stability by correcting DNA replication errors. The present study investigated the effects of p38 mitogen-activated protein kinase (MAPK) signal on gefitinib-induced MSH2 expression in two human non-small cell lung squamous cancer cell lines. Materials and methods: After the gefitinib treatment, the expressions of MSH2 mRNA were determined by real-time PCR and RT-PCR analysis. Protein levels of MSH2, phospho-MKK3/6, phospho-p38 MAPK were determined by Western blot analysis. We used specific MSH2, and p38 MAPK small interfering RNA to examine the role of p38 MAPK-MSH2 signal in regulating the chemosensitivity of gefitinib. Cell viability was assessed by MTS assay, trypan blue exclusion, and colony-forming ability assay. Results: Exposure of gefitinib increased MSH2 protein and mRNA levels, which was accompanied by MKK3/6-p38 MAPK activation in H520 and H1703 cells. Moreover, blocking p38 MAPK activation by SB202190 significantly decreased gefitinib-induced MSH2 expression by increasing mRNA and protein instability. In contrast, enhancing p38 activation using constitutively active MKK6 (MKK6E) increased MSH2 protein and mRNA levels. Specific inhibition of MSH2 expression by siRNA enhanced gefitinib-induced cytotoxicity. Metformin, an anti-diabetic drug, might reduce cancer risk. In human lung squamous cancer cells, metformin decreased gefitinib-induced MSH2 expression and augmented the cytotoxic effect and growth inhibition by gefitinib. Transient expression of MKK6E or HA-p38 MAPK vector could abrogate metformin and gefitinib-induced synergistic cytotoxic effect in H520 and H1703 cells. Conclusion: Together, down-regulation of MSH2 expression can be a possible strategy to enhance the sensitivity of gefitinib to human lung squamous cancer cells. ? 2013 Elsevier Ireland Ltd.
SDGs
Other Subjects
gefitinib; messenger RNA; metformin; mitogen activated protein kinase kinase 3; mitogen activated protein kinase kinase 6; mitogen activated protein kinase p38; protein MSH2; small interfering RNA; trypan blue; article; cancer cell; cancer cell culture; cancer inhibition; cancer risk; cell viability; chemosensitivity; colony forming unit; controlled study; cytotoxicity; down regulation; drug mechanism; drug potentiation; human; human cell; lung non small cell cancer; lung squamous cell carcinoma; priority journal; protein expression; real time polymerase chain reaction; reverse transcription polymerase chain reaction; risk reduction; transient expression; Western blotting; Cytotoxicity; Gefitinib; Metformin; MSH2; Non-small cell lung cancer; p38 MAPK; Tyrosine kinase inhibitor; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Cell Survival; Chemotherapy, Adjuvant; Drug Synergism; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Lung Neoplasms; MAP Kinase Kinase 3; MAP Kinase Kinase 6; Metformin; Mutation; MutS Homolog 2 Protein; p38 Mitogen-Activated Protein Kinases; Pyridines; Quinazolines; RNA, Small Interfering; Signal Transduction; Transgenes
Type
journal article