MEK Inhibitor for Gastric Cancer with MEK1 Gene Mutations

Abstract

The prognosis for patients with unresectable advanced or recurrent gastric cancer remains poor. The identification of additional oncogenes with influences similar to those of epidermal growth factor receptor gene mutations, upon which the growth of cancer cells is dependent, is needed. In this study, we evaluated sensitivity to MEK inhibitors (GSK1120212 and PD0325901) in several gastric cancer cell lines in vitro and found three poorly differentiated gastric cancer cell lines that were hypersensitive to the inhibitors. The sequence analyses in these three cell lines revealed that one cell line had a novel MEK1 mutation, while the other two had previously reported KRAS and MEK1 mutations, respectively; the gene statuses of the other resistant cell lines were all wild-type. Experiments using MEK1 expression vectors demonstrated that the MEK1 mutations induced the phosphorylation of ERK1/2 and had a transforming potential, enhancing the tumorigenicity. The MEK inhibitor dramatically reduced the phosphorylation of ERK1/2 and induced apoptosis in the cell lines with MEK1 mutations. In vivo, tumor growth was also dramatically decreased by an inhibitor. One of the 46 gastric cancer clinical samples that were examined had a MEK1 mutation; this tumor had a poorly differentiated histology. Considering the addiction of cancer cells to active MEK1 mutations for proliferation, gastric cancer with such oncogenic MEK1 mutations might be suitable for targeted therapy with MEK inhibitors.

EGFR and HER2 signals play a salvage role in MEK1-mutated gastric cancer after MEK inhibition

“…Somatic oncogenic MEK1 mutations have also been identified in several human malignancies (18)(19)(20)(21). In addition, our previous study demonstrated that MEK1 mutations in poorly differentiated GC cell lines that are hypersensitive to MEK inhibitors have transformational abilities and that the growth of these cancer cells is dependent on these mutations (22). Considering the addiction of cancer cells to active MEK1 mutations for proliferation, GC with such oncogenic MEK1 mutations might be suitable for targeted therapy with MEK inhibitors.…”

Afatinib against Esophageal or Head-and-Neck Squamous Cell Carcinoma: Significance of Activating Oncogenic HER4 Mutations in HNSCC

“…The cellular growth and growth-inhibitory effects of the drugs or siRNA were examined using a 3, 4, 5-dimethyl-2H-tetrazolium bromide assay (MTT; Sigma-Aldrich), as described previously (26). The experiment was performed in triplicate.…”

“…The PCR products were then directly sequenced using the BigDye Terminator v3.1 Sequencing Kit (Applied Biosystems), as previously described (26).…”

“…A western blot analysis was performed as described previously (26). Briefly, subconfluent cells were washed with cold phosphate-buffered saline (PBS) and harvested with Lysis A buffer containing 1% Triton X-100, 20 mmol/L Tris-HCl (pH7.0), 5 mmol/L EDTA, 50 mmol/L sodium chloride, 10 mmol/L sodium pyrophosphate, 50 mmol/L sodium fluoride, 1 mmol/L sodium orthovanadate, and a protease inhibitor mix, Complete (Roche Diagnostics).…”

“…The tumor formation and volume were assessed twice a week. These methods have been previously described (26,27).…”