Functional characterization of CLPTM1L as a lung cancer risk candidate gene in the 5p15.33 locus.
Cleft Lip and Palate Transmembrane Protein 1-Like (CLPTM1L), resides in a region of chromosome 5 for which copy number gain has been found to be the most frequent genetic event in the early stages of non-small cell lung cancer (NSCLC). This locus has been found by multiple genome wide association studies to be associated with lung cancer in both smokers and non-smokers. CLPTM1L has been identified as an overexpressed protein in human ovarian tumor cell lines that are resistant to cisplatin, which is the only insight thus far into the function of CLPTM1L. Here we find CLPTM1L expression to be increased in lung adenocarcinomas compared to matched normal lung tissues and in lung tumor cell lines by mechanisms not exclusive to copy number gain. Upon loss of CLPTM1L accumulation in lung tumor cells, cisplatin and camptothecin induced apoptosis were increased in direct proportion to the level of CLPTM1L knockdown. Bcl-xL accumulation was significantly decreased upon loss of CLPTM1L. Expression of exogenous Bcl-xL abolished sensitization to apoptotic killing with CLPTM1L knockdown. These results demonstrate that CLPTM1L, an overexpressed protein in lung tumor cells, protects from genotoxic stress induced apoptosis through regulation of Bcl-xL. Thus, this study implicates anti-apoptotic CLPTM1L function as a potential mechanism of susceptibility to lung tumorigenesis and resistance to chemotherapy.
MCW Cancer Center, Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America.
Michael A
MA
James
Weidong
W
Wen
Yian
Y
Wang
Lauren A
LA
Byers
John V
JV
Heymach
Kevin R
KR
Coombes
Luc
L
Girard
John
J
Minna
Ming
M
You
D000230:Adenocarcinoma / Q000235:genetics; D000077192:Adenocarcinoma of Lung; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002895:Chromosomes, Human, Pair 5 / Q000235:genetics*; D004249:DNA Damage / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056726:Genetic Association Studies; D056426:Genetic Loci / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D009153:Mutagens / Q000633:toxicity; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D012307:Risk Factors; D051020:bcl-X Protein / Q000378:metabolism
C422445:CLPTM1L protein, human; D008565:Membrane Proteins; D009153:Mutagens; D009363:Neoplasm Proteins; D051020:bcl-X Protein