Open AccessTIMELESS is overexpressed in lung cancer and its expression correlates with poor patient survival
Author(s) -
Yoshida Kenya,
Sato Mitsuo,
Hase Tetsunari,
Elshazley Momen,
Yamashita Ryo,
Usami Noriyasu,
Taniguchi Tetsuo,
Yokoi Kohei,
Nakamura Shigeo,
Kondo Masashi,
Girard Luc,
Minna John D.,
Hasegawa Yoshinori
Publication year - 2013
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/cas.12068
Subject(s) - lung cancer , gene knockdown , timeless , immunohistochemistry , biology , cancer research , western blot , cell growth , cancer , clonogenic assay , apoptosis , cell culture , pathology , microbiology and biotechnology , medicine , immunology , gene , circadian rhythm , endocrinology , genetics
TIMELESS ( TIM ) is a mammalian homolog of a Drosophila circadian rhythm gene, but its circadian properties in mammals have yet to be determined. TIM appears to be essential for replication protection and genomic stability. Recently, the involvement of TIM in human malignancies has been reported; therefore, we investigated the role of TIM in lung cancer. Microarray expression analysis of lung cancer cell lines showed that TIM expression was elevated 3.7‐fold ( P < 0.001) in non‐small cell lung cancer cell lines ( n = 116) compared to normal lung controls ( n = 59). In addition, small cell lung cancer cell lines ( n = 29) expressed TIM at levels 2.2‐fold ( P < 0.001) higher than non‐small cell lung cancer. Western blot analysis of 22 lung cancer cell lines revealed that all of them expressed TIM protein and that 20 cell lines (91%) expressed TIM protein at higher levels than a normal control line. Remarkably, immunohistochemistry of 30 surgically resected lung cancer specimens showed that all lung cancer specimens but no matched normal lung tissues were positive for TIM expression. Moreover, immunohistochemistry of surgically resected specimens from 88 consecutive patients showed that high TIM protein levels correlated with poor overall survival ( P = 0.013). Mutation analysis for TIM in 23 lung cancer cell lines revealed no mutation. TIM knockdown suppressed proliferation and clonogenic growth, and induced apoptosis in H157 and H460 cells. Taken together, our findings suggest that TIM could be useful as a diagnostic and prognostic marker for lung cancer and targeting it would be of high therapeutic value for this disease.