Abstract
Adenocarcinoma is the most common histological type of lung cancer and has various histologic subtypes, including lepidic, papillary, acinar and invasive mucinous adenocarcinoma. Histologic subtypes are associated with tumor invasiveness. For example, the lepidic subtype is less invasive than the papillary/acinar subtype. Trefoil factor 3 (TFF3) is a small secreting protein that is a member of the trefoil factor family, which is involved in mucosal stabilization and repair through its mitogenic and antiapoptotic activities. TFF3 overexpression is associated with various types of cancer. In lung cancer, TFF3 is expressed significantly in adenocarcinoma. However, the relationship between TFF3 expression and histologic subtypes in lung adenocarcinoma is unclear. The current study immunohistochemically revealed that, beside invasive mucinous carcinoma, the expression of TFF3 in papillary and acinar adenocarcinoma was significantly higher than that in lepidic adenocarcinoma. To further confirm these results, the expression of TFF3 in cases with both lepidic and papillary/acinar areas were examined. The expression of TFF3 in papillary/acinar areas was significantly higher when compared with lepidic areas in a single sample. Furthermore, using the lung adenocarcinoma cell line A549, TFF3-knockdown cells were generated. The results revealed that knockdown of TFF3 attenuated invasion. In vitro and immunohistochemical assays using clinical samples demonstrated that TFF3 expression was associated with lung adenocarcinoma invasiveness. To the best of our knowledge, the current study is the first to report that TFF3 expression was associated with the histologic subtypes of lung adenocarcinoma.