MDA-7/IL-24 Expression and Its Relation with Clinicopathologic Factors in Lung Adenocarcinomas of 3 cm or Less in Diameter

Expression and Its Relation with Clinicopathologic Factors in Lung Adenocarcinomas of 3 cm or Less in DiameterPurpose: The melanoma differentiation-associated gene-7 (MDA-7) protein, also known as interleukin 24 (IL-24), is a novel candidate of tumor suppressor that has been found to experimentally induce apoptosis and growth inhibition in a variety of human malignant cells.However, there have been few studies about its role in lung adenocarcinoma.Even at the same stage and with similar pathologic characteristics, lung adenocarcinomas with a diameter of 3 cm or less can have a variable prognosis depending on their biologic characteristics.The purpose of this study is to define the relationship between MDA-7/IL-24 expression and the progression of small-sized lung adenocarcinomas.Materials and Methods: We performed immunohistochemical detection of MDA-7/ IL-24 in forty-seven tissue samples from primary lung adenocarcinomas of ≤3 cm in diameter by using tissue microarray.Results: MDA-7/IL-24 immunoreactivity was observed in 20 (42.6%) of the 47 adenocarcinoma cases.MDA-7/IL-24 expression was positive in 66.7% of the adenocarcinomas ≤2 cm, and in 31.3% of the adenocarcinomas ＞2 cm or ≤3 cm in diameter.A statistically significant association was found between MDA-7/IL-24 expression and tumor size (p=0.03).Although this difference did not reach statistical significance, tumors with a negative MDA-7/IL-24 expression tended to more frequently show lymph node metastasis (p=0.07).There were no significant associations for other clinicopathologic characteristics.Conclusion: These results suggest the possible involvement of MDA-7/IL-24 in the growth and progression of small-sized lung adenocarcinoma.MDA-7/IL-24 immunoreactivity could be used to identify a subset of adenocarcinomas of the lung of 3 cm or less in diameter that have different biologic behavior.(J Lung Cancer 2012;11(2): 71󰠏 76)