AUTHOR=Tsuruda Toshihiro , Sato Yuichiro , Tomita Masaki , Tanaka Hiroyuki , Hatakeyama Kinta , Otsu Misa , Kawano Aya , Nagatomo Keiko , Yoshikawa Naoki , Ikeda Ryuji , Asada Yujiro , Kaikita Koichi 

TITLE=Aberrant Expression of Cardiac Troponin-T in Lung Cancer Tissues in Association With Pathological Severity

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2022.833649

DOI=10.3389/fcvm.2022.833649

ISSN=2297-055X

ABSTRACT=<sec><title>Background</title><p>Cardiac troponin-T (<italic>TNNT2</italic>) is exclusively present in cardiac muscle. Measurement of <italic>TNNT2</italic> is used for diagnosing acute coronary syndrome. However, its expression may not be limited in myocardium. This study aimed at evaluating the expression of <italic>TNNT2</italic> in neoplastic tissues.</p></sec><sec><title>Methods and Results</title><p>We used paraffin-embedded blocks of 68 patients with lung cancer (age, 68 ± 11 years old; early-stage, 33; advance-stage, 35) at Miyazaki University Hospital, Japan between January 1, 2017, and March 31, 2019. We stained the slide sections with primary monoclonal antibody against <italic>TNNT2</italic> protein, and assessed the frequency of positive staining, and its association with pathological severity. In addition, we examined whether <italic>TNNT2</italic> gene is detected in lung cancer tissues of four patients using reverse transcription-polymerase chain reaction. Immunoreactivity for <italic>TNNT2</italic> protein was present in the cytoplasm and nucleus of lung cancer cells. The frequency was 37% (25 of 68) in all patients and was irrespective of histologic type (six of 13, squamous cell carcinoma; 18 of 50, adenocarcinoma; 0 of 4, neuroendocrine cell carcinoma; 1 of 1, large cell carcinoma). The prevalence increased with pathological staging [9% (3 of 33) at early-stage (Stage 0–I); 63% (22 of 35) at advance-stage (Stage II–IV and recurrence)]. In addition, frequency of positive staining for <italic>TNNT2</italic> increased with pleural (χ<sup>2</sup> = 5.877, <italic>P</italic> = 0.015) and vascular (χ<sup>2</sup> = 2.449, <italic>P</italic> = 0.118) invasions but decreased with lymphatic invasion (χ<sup>2</sup> = 3.288, <italic>P</italic> = 0.070) in specimens performed surgical resection. Furthermore, <italic>TNNT2</italic> mRNA was detected in the resected squamous cell carcinoma and adenocarcinoma tissues.</p></sec><sec><title>Conclusions</title><p>Our data suggest the aberrant expression of <italic>TNNT2</italic> in lung cancer and its prevalence increases with pathological severity.</p></sec>