Abstract 5531: Lumican as a novel differential diagnostic maker for Bowen's disease and actinic keratosis

Abstract

Abstract BACKGROUND: Lumican is a member of the small leucine-rich proteoglycan (SLRP) family and regulates the assembly and diameter of collagen fibrils in the extracellular matrix in human tissue. Mice homozygous for a null mutation in lumican display corneal opacification and skin laxity. Recent studies have shown that lumican is expressed in various types of malignant tumors including breast, colorectal, and pancreatic cancer, and osteosarcoma and malignant melanoma, and that it plays an important role in the growth of tumors. However, little has been studied about the expression pattern and role of lumican in non-melanoma skin cancer. In this study, we examined the expression levels of lumican in in situ lesions of squamous cell carcinoma (SCC) of the skin, actinic keraotsis and Bowen's disease, to discover whether lumican can be used as a novel differential diagnostic marker for such skin tumors, particularly for bowenoid actinic keratosis and Bowen's disease in sun-exposed areas of the body. Bowenoid actinic keratosis and Bowen's disease are often difficult to distinguish in both the clinical setting and commonly prepared pathological specimens. Furthermore, invasive SCC arising in actinic keratosis is considered low-risk clinically, while Bowen's disease with invasion is considered high-risk. Thus, it is important to distinguish between actinic keratosis and Bowen's disease, and reliable differential markers for these diseases are required.METHOD: Twenty-nine cases of actinic keratosis, including 4 of the bowenoid sub-type, and 37 cases of Bowen's disease, including 6 in sun-exposed areas of the body, were selected from among patients undergoing surgical resection at the Department of Dermatology at the Nippon Medical School from 2006 to 2010. We evaluated lumican expression and mRNA in these cases using immunohistochemistry and in situ hybridization analysis, respectively. RESULTS: Immunohistochemical analysis indicated that Lumican was expressed in 34 of 37 patients with Bowen's disease (91.8%), but was not detected in any of the cases of actinic keratosis. In situ hybridization analysis revealed that lumican mRNA was expressed in the cytoplasm of immunohistochemically lumican-positive tumor cells in Bowen's disease. CONCLUSION: These findings suggest that lumican plays an important role in the pathogenesis of Bowen's disease and will be a useful marker for the differential diagnosis between Bowen's disease and actinic keratosis, particularly for bowenoid actinic keratosis and Bowen's disease occurring in sun-exposed areas of the body. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5531. doi:1538-7445.AM2012-5531