KIF5B-ALK, a novel fusion oncokinase identified by an immunohistochemistry-based diagnostic system for ALK-positive lung cancer.
OBJECTIVE
EML4-ALK is a transforming fusion tyrosine kinase, several isoforms of which have been identified in lung cancer. Immunohistochemical detection of EML4-ALK has proved difficult, however, likely as a result of low transcriptional activity conferred by the promoter-enhancer region of EML4. The sensitivity of EML4-ALK detection by immunohistochemistry should be increased adequately.


METHODS
We developed an intercalated antibody-enhanced polymer (iAEP) method that incorporates an intercalating antibody between the primary antibody to ALK and the dextran polymer-based detection reagents.


RESULTS
Our iAEP method discriminated between tumors positive or negative for EML4-ALK in a test set of specimens. Four tumors were also found to be positive for ALK in an archive of lung adenocarcinoma (n = 130) and another 4 among fresh cases analyzed in a diagnostic laboratory. These 8 tumors were found to include 1 with EML4-ALK variant 1, 1 with variant 2, 3 with variant 3, and 2 with previously unidentified variants (designated variants 6 and 7). Inverse reverse transcription-PCR analysis revealed that the remaining tumor harbored a novel fusion in which intron 24 of KIF5B was ligated to intron 19 of ALK. Multiplex reverse transcription-PCR analysis of additional archival tumor specimens identified another case of lung adenocarcinoma positive for KIF5B-ALK.


CONCLUSIONS
The iAEP method should prove suitable for immunohistochemical screening of tumors positive for ALK or ALK fusion proteins among pathologic archives. Coupling of PCR-based detection to the iAEP method should further facilitate the rapid identification of novel ALK fusion genes such as KIF5B-ALK.
Takeuchi
Kengo
K
The Cancer Institute, Japanese Foundation for Cancer Research, Japan. kentakeuchi-tky@umin.net
Choi
Young Lim
YL
Togashi
Yuki
Y
Soda
Manabu
M
Hatano
Satoko
S
Inamura
Kentaro
K
Takada
Shuji
S
Ueno
Toshihide
T
Yamashita
Yoshihiro
Y
Satoh
Yukitoshi
Y
Okumura
Sakae
S
Nakagawa
Ken
K
Ishikawa
Yuichi
Y
Mano
Hiroyuki
H
D016475:3T3 Cells; D000230:Adenocarcinoma / Q000201:enzymology*; D000077548:Anaplastic Lymphoma Kinase; D000818:Animals; D000911:Antibodies, Monoclonal; D002289:Carcinoma, Non-Small-Cell Lung / Q000201:enzymology*; D002471:Cell Transformation, Neoplastic; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D014644:Genetic Variation; D006801:Humans; D007124:Immunoenzyme Techniques; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008175:Lung Neoplasms / Q000201:enzymology*; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry; D011379:Prognosis; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000911:Antibodies, Monoclonal; C522504:EML4-ALK fusion protein, human; C488101:KIF5B protein, human; D015514:Oncogene Proteins, Fusion; D011108:Polymers; D012333:RNA, Messenger; C000626173:ALK protein, human; C000626174:Alk protein, mouse; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D016547:Kinesins