Downregulation of tazarotene induced gene-2 (TIG2) in skin squamous cell carcinoma

Tazarotene, an RARβ/γ-selective synthetic retinoid, was found to induce three genes, tazarotene-induced genes (TIG) 1, 2 and 3. TIG2 was abundantly expressed in non-lesional psoriatic skin, but at lower levels in psonatic lesions. The protein precursor encoded by TIG2, called prochemerin, can be converted into bioactive chemerin. Chemerin can then bind to chemerin receptor, resulting in chemoattracting dendritic cells and macrophages, and serving as a bridge between innate and adaptive immunity. Our objective was to investigate the role of TIG2 in skin squamous cell carcinoma (SCC). The levels of TIG2-protein and transcript in normal skin tissues, uninvolved skin and SCC lesions were determined by immunohistochemistry and in situ hybridization. TIG2-protein and transcript were detected in all layers of normal epidermis and uninvolved skin adjacent to SCC lesions. In addition, TIG2 was also expressed in the corneum, granular layers and the upper and middle layers of stratum spinosum of the marginal part of SCC lesions. On the other hand, TIG2-protein and transcript were barely detectable around the keratin pearls of SCC 1-2, and were not detectable at all in SCC 3-4.