Multiplex reverse transcription-PCR screening for EML4-ALK fusion transcripts.

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion protein is a key driver in a subset of non-small cell lung cancer (NSCLC).
• Accurate detection of EML4-ALK fusion transcripts is crucial for targeted therapy selection in NSCLC patients.

Purpose of the Study:

• To develop and validate a sensitive multiplex reverse transcription-PCR (RT-PCR) system for detecting all in-frame EML4-ALK fusion transcripts.
• To identify novel EML4-ALK fusion variants in non-small cell lung cancer (NSCLC) specimens.

Main Methods:

• A single-tube multiplex RT-PCR assay was designed using primers targeting all possible in-frame fusions between EML4 and ALK.
• The assay was performed on RNA extracted from 656 solid tumors, including 364 lung tumors and tumors from 10 other organs.
• Genomic PCR and fluorescence in situ hybridization (FISH) were used to confirm genomic rearrangements.

Main Results:

• The multiplex RT-PCR assay detected EML4-ALK fusion transcripts in 4.35% (11/253) of lung adenocarcinoma cases.
• Nine positive cases harbored known EML4-ALK variants (1, 2, and 3), while two cases presented novel transcript isoforms (variant 4 and 5).
• No fusion transcripts were found in other lung cancer types or tumors from other organs, and novel isoforms showed oncogenic activity.

Conclusions:

• The developed multiplex RT-PCR system offers sensitive detection of EML4-ALK fusion transcripts, including novel isoforms.
• Accurate diagnosis of EML4-ALK-positive NSCLC is essential for optimizing patient treatment strategies.
• Identification of novel EML4-ALK variants may expand the scope of targeted therapies in NSCLC.