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

ABSTRACT

PURPOSE: 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 2 cm or < 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.