Diversity of EML4-ALK fusion variants in non-small cell lung cancer / 中华检验医学杂志

ABSTRACT

ObjectiveTo investigate the fusion sequence complexity of EML4-ALK in non-small cell lung cancer (NSCLC) patients,and the potential mutation in tyrosine kinase ( TK ) domain of ALK gene.MethodsIn routine practice,a novel echinoderm microtubule-associated protein-like4 and anaplastic lymphoma kinase (EML4-ALK) V3c variant was detected by rapid amplification of cDNA ends-polymerase chain reaction ( RACE-PCR )-sequencing technology in a patient with NSCLC.The further consecutive 39 cases( total of 40 cases)were screened by use of reverse transcription (RT)-PCR for EML4-ALK fusion.Positive PCR products were purified and cloned into T vectors,transformed into DH5a germ cells and colony picked up and sequenced for sequence complexity analysis.Tyrosine kinase domain of ALK was amplified by RT-PCR and sequenced.ResultsThree out of 40 cases had EML4-ALK fusion.One case had six novel variants of EML4-ALK co-existing,termed as V3c ( 64.6％ ),V3d ( 25.0％ ),V3e ( 2.1％ ),V3f (4.2％ ),V3g(2.1％ )and V3h(2.1％ ) variants,whereas without common V3a and V3b variants.In other two positive cases,one was V1 variant,another was concurrent V2,V3a and V3b variants.No mutations were detected in the TK domain of EML4-ALK in any case.ConclusionsSeveral EML-ALK variants could co-exist in a given lung cancer tissue,which suggest that the diversity and sequence complexity of EML4-ALK fusion are exist.Attentions should be paid to screen all the variants in clinic to improve the pick-up rate.