Genetic screening and molecular characterization of MET alterations in non-small cell lung cancer

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Aberrant MET activation via MET exon 14-skipping (METex14) mutations or gene amplification is a significant oncogenic mechanism in non-small cell lung carcinoma (NSCLC).
• These MET alterations represent potential therapeutic targets in NSCLC treatment strategies.

Purpose of the Study:

• To characterize the prevalence and spectrum of MET alterations in a cohort of surgically treated NSCLC patients.
• To investigate the correlation between MET genetic alterations and protein expression levels.

Main Methods:

• Analysis of 157 NSCLC cases, including pulmonary sarcomatoid carcinomas (PSC), for MET alterations.
• Utilized Sanger sequencing for METex14 mutations, fluorescence in situ hybridization for copy number alterations, and immunohistochemistry for MET protein levels.
• Assessed concurrent genetic alterations and downstream signaling via phospho-S6 immunostaining.

Main Results:

• METex14 mutations and MET amplification were identified in seven NSCLC tumors, predominantly in lung adenocarcinoma and PSC.
• High MET protein levels were observed in most MET-amplified cases but not consistently in METex14-mutated tumors.
• Downstream signaling activation (phospho-S6) was noted in about half of MET-activated tumors, with one case showing concurrent ERBB2 amplification.

Conclusions:

• MET activation through METex14 mutations or amplification is characteristic of a subset of early-stage NSCLCs.
• Coexistence of MET alterations with ERBB2 amplification suggests potential for combinatorial therapies.
• Low MET protein levels in some METex14-mutated NSCLCs may limit the utility of total MET immunostaining for patient preselection in targeted therapy.