Cardiac troponin I is abnormally expressed in non-small cell lung cancer tissues and human cancer cells

Cardiac troponin I (cTnI) is the only sarcomeric protein identified to date that is expressed exclusively in cardiac muscle. Its expression in cancer tissues has not been reported. Herein, we examined cTnI expression in non-small cell lung cancer (NSCLC) tissues, human adenocarcinoma cells SPCA-1 (l...

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Bibliographic Details
Published in:International journal of clinical and experimental pathology 2014-01, Vol.7 (4), p.1314-1324
Main Authors: Chen, Chao, Liu, Jia-Bao, Bian, Zhi-Ping, Xu, Jin-Dan, Wu, Heng-Fang, Gu, Chun-Rong, Shi, Yi, Zhang, Ji-Nan, Chen, Xiang-Jian, Yang, Di
Format: Article
Language:English
Subjects:
Adenocarcinoma - metabolism
Adenocarcinoma - pathology
Carcinoma, Non-Small-Cell Lung - metabolism
Carcinoma, Non-Small-Cell Lung - pathology
Carcinoma, Squamous Cell - metabolism
Carcinoma, Squamous Cell - pathology
Cell Line, Tumor
Gene Expression Regulation, Neoplastic
Humans
Immunohistochemistry
Lung - metabolism
Lung - pathology
Lung Neoplasms - metabolism
Lung Neoplasms - pathology
Myocytes, Cardiac - metabolism
Myocytes, Cardiac - pathology
Original
Real-Time Polymerase Chain Reaction
Stomach - metabolism
Stomach - pathology
Stomach Neoplasms - metabolism
Stomach Neoplasms - pathology
Troponin I - genetics
Troponin I - metabolism
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Summary:Cardiac troponin I (cTnI) is the only sarcomeric protein identified to date that is expressed exclusively in cardiac muscle. Its expression in cancer tissues has not been reported. Herein, we examined cTnI expression in non-small cell lung cancer (NSCLC) tissues, human adenocarcinoma cells SPCA-1 (lung) and BGC 823 (gastric) by immunohistochemistry, western blot analysis and real-time PCR. Immunopositivity for cTnI was demonstrated in 69.4% (34/49) NSCLC tissues evaluated, and was strong intensity in 35.3% (6/17) lung squamous cell carcinoma cases. The non-cancer-bearing lung tissues except tuberculosis (9/9, 100%) showed negative staining for cTnI. Seven monoclonal antibodies (mAbs) against human cTnI were applied in immunofluorescence. The result showed that the staining pattern within SPCA-1 and BGC 823 was dependent on the epitope of the cTnI mAbs. The membrane and nucleus of cancer cells were stained by mAbs against N-terminal peptides of cTnI, and cytoplasm was stained by mAbs against the middle and C-terminal peptides of cTnI. A ~25 kD band was identified by anti-cTnI mAb in SPCA-1 and BGC 823 extracts by western blot, as well as in cardiomyocyte extracts. The cTnI mRNA expressions in SPCA-1 and BGC 823 cells were about ten thousand times less than that in cardiomyocytes. Our study shows for the first time that cTnI protein and mRNA were abnormally expressed in NSCLC tissues, SPCA-1 and BGC 823 cells. These findings challenge the conventional view of cTnI as a cardiac-specific protein, enabling the potential use of cTnI as a diagnostic marker or targeted therapy for cancer.
ISSN:1936-2625