title: KRAS mutant lung cancer cells are differentially responsive to MEK inhibitor due to AKT or STAT3 activation: implication for combinatorial approach.
abstract: KRAS is frequently mutated in nonsmall cell lung cancer (NSCLC), resulting in the activation of the MAPK/ERK kinase (MEK)/ERK pathway. High-throughput mutation profile has shown that lung cancer frequently harbors comutation of cancer-related genes. Therefore, given that cancer cells have multiple genetic alterations, combinatorial therapeutic strategy is demanded for effective cancer therapy. To address this, we first characterized MEK dependence in four NSCLC cells. Two cells (H358, A549) carried KRAS mutation only, and the other two (H23, H157) harbored comutation of KRAS/PTEN. H358 cells with KRAS mutation only were sensitive to MEK inhibition. However, the other KRAS mutant A549 cells were resistant to MEK inhibition. Previously, we have shown that dual inhibition of EGFR and MEK signaling shows a synergistic effect on KRAS mutant gastric cancer cells by suppressing compensatory activation of AKT. Here we also observed that this combination was effective in KRAS mutant A549 cells. However, the combination was ineffective in H23 and 157 cells with comutation of KRAS/PTEN. Compared to KRAS mutant/PTEN wild-type cells, signal transducer and activator of transcription 3 (STAT3) was significantly activated following MEK inhibition in KRAS/PTEN comutant cells. Combined STAT3 inhibition by a JAK2 inhibitor or gene knockdown with MEK inhibition blocked STAT3 activation, synergistically suppressed cell growth, and induced apoptosis in comutant cells. Taken together, our study provides molecular insights that help explain the heterogeneous response to MEK inhibition in KRAS mutant lung cancers, and presents a rationale for the clinical investigation of combination of MEK and EGFR inhibitor or MEK and JAK2 inhibitor depending on PTEN status.
authors.affiliation: Cancer Research Institute, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 110-744, Korea.
authors.forename: Young-Kwang
authors.initials: YK
authors.lastname: Yoon
authors.forename: Hwang-Phill
authors.initials: HP
authors.lastname: Kim
authors.forename: Sae-Won
authors.initials: SW
authors.lastname: Han
authors.forename: Do Youn
authors.initials: DY
authors.lastname: Oh
authors.forename: Seock-Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Yung-Jue
authors.initials: YJ
authors.lastname: Bang
authors.forename: Tae-You
authors.initials: TY
authors.lastname: Kim
mesh_terms: D001562:Benzimidazoles / Q000494:pharmacology; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011905:Genes, ras / Q000187:drug effects*; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D009154:Mutation / Q000187:drug effects; D051059:PTEN Phosphohydrolase / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics* / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: C517975:AZD 6244; D001562:Benzimidazoles; D004791:Enzyme Inhibitors; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051057:Proto-Oncogene Proteins c-akt; D020929:Mitogen-Activated Protein Kinase Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human