Regulation of MET kinase inhibitor resistance by copy number of MET in gastric carcinoma cells.

Abstract

We previously established acquired resistant models for MET-tyrosine kinase inhibitors (TKIs) by continuously exposing the MET-amplified gastric cancer cell line MKN45 to MET-TKIs, PHA665752 (MKN45-PR), or GSK1363089 (MKN45-GR). We found resistant mechanisms caused by increased copy number of MET in both lines and Y1230H mutation in MKN45-PR. We also found that excessive MET signaling caused by these MET alterations resulted in intra-S-phase arrest in the absence of MET-TKIs, so that cells grew faster in the presence of MET-TKIs, a phenomenon referred to as "addiction." In this study, to investigate reversibility of the acquired resistance and "addiction" to MET-TKIs and their causative MET alterations, we sequentially cultured MKN45-PR and MKN45-GR in decreasing concentrations of MET-TKIs until they were able to grow in a drug-free condition. These "revertant" cell lines (designated MKN45-PR-RE and MKN45-GR-RE) were comparatively analyzed. Growth assay showed that both MKN45-PR-RE and MKN45-GR-RE partially lost the property of "addiction" to MET-TKIs. MKN45-GR-RE lost the property of resistance to GSK1363089, but MKN45-PR-RE retained resistance to PHA665752. Copy numbers and expression and phosphorylation of MET protein reduced in both MKN45-PR-RE and MKN45-GR-RE compared with MKN45-PR and MKN45-GR, respectively, but Y1230H mutation and biochemical resistance to PHA665752 remained in MKN45-PR-RE. The "addiction" to MET-TKIs appeared attributable to increased copy number, and the property and the MET alteration were reversible. The Y1230H mutation appeared enough in itself to keep cells resistant to MET-TKIs and was irreversible.

• Authors: Yohei Funakoshi, Toru Mukohara, Roudy Chiminch Ekyalongo, Hideo Tomioka, Yu Kataoka, Yohei Shimono, Naoko Chayahara, Masanori Toyoda, Naomi Kiyota, Yutaka Fujiwara, Hironobu Minami
• Journal: Oncology research (Oncol Res) Vol. 21 Issue 6 Pg. 287-93 ( 2013) ISSN: 1555-3906 [Electronic] United States
• PMID: 25198658 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Protein Kinase Inhibitors
• Proto-Oncogene Proteins c-met

Topics

• Carcinoma (genetics, metabolism)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• DNA Mutational Analysis
• Dose-Response Relationship, Drug
• Drug Resistance, Neoplasm (genetics)
• Gene Dosage
• Humans
• Mutation
• Protein Kinase Inhibitors (pharmacology)
• Proto-Oncogene Proteins c-met (antagonists & inhibitors, genetics)
• Signal Transduction (drug effects)
• Stomach Neoplasms (genetics, metabolism)