Incidence of melanoma continues to rise, and a better understanding of its genetics will be critical to improve diagnosis and develop new treatments. Here, we search for novel melanoma-specific genes that may serve as biomarkers and therapeutic targets by using an in vitro genetic screen. One identified cDNA encoded TROY, a member of the tumor necrosis factor receptor superfamily (TNFRSF). TROY is widely expressed during embryogenesis, but in adults expression is restricted to hair follicles and brain. However, TROY had never been associated with melanoma, and it was selected for further study. First we show that expression in melanoma is specific by semiquantitative RT-PCR analysis of a large panel of established tumor cell lines. Next, specificity of expression was evaluated by immunohistochemistry analysis of primary cell cultures and patient tissues. TROY is expressed in 2/2 primary melanoma cells and 45/45 melanoma tissue samples (p < 0.0001). With the exception of sebaceous glands, TROY is not expressed in normal skin biopsies (p < 0.0001) or primary skin cell cultures that contain keratinocytes and epidermal melanocytes, nor is it expressed in other skin tumor cells (p < 0.0001). Finally, we show that TROY regulates melanoma growth, because replication of melanoma cells with reduced TROY levels through treatment with short-interfering RNA was significantly decreased relative to control cells (p < 0.004). In summary, TROY is the first TNFRSF member that is a biomarker for melanoma. TROY also presents a potentially novel cell surface signaling target for inhibitors, cell and/or antibody-based immunotherapies. ' 2006 Wiley-Liss, Inc.

Despite the absence of enzymes that digest extracellular matrix, Borrelia burgdorferi spreads in the skin to form erythema migrans (EM) lesions and then disseminates to other organs. We studied the induction by bacteria of host matrix metalloproteinases (MMPs) in EM skin lesions of patients with acute Lyme disease. In blister fluid from the EM lesions, the expression of MMP-9 was selectively increased by 1900%+/-1037%, compared with blister fluid from the surrounding normal-appearing skin. The expression of all other MMP messenger RNAs was similar in the EM lesions and normal-appearing skin. Selective up-regulation of MMP-9 in the EM lesions was found. Fibroblasts and, to a lesser degree, mononuclear cells were the sources of local MMP-9 production. These results demonstrate specific up-regulation of MMP-9 in the EM skin lesions of patients with acute Lyme disease. Bacterial induction of host proteases may play a role in the dissemination of B. burgdorferi.

Our results demonstrate that K16 expression is also observed in non-lesional psoriatic skin and may serve as a marker of preclinical psoriasis.

Although the prevailing dogma states that keratin filaments are the hallmark of keratinocytes and other epithelial cells, recent publications suggest that they may be expressed by a variety of normal and malignant cells of different embryonic origin. Keratin expression has been reported in fibroblasts and endothelial cells as well as in various sarcomas. Also, some human melanomas express keratins in addition to the traditional diagnostic markers of differentiation, such as S-100 and melanocyte-specific antigens. Many studies have shown that cultured cells obtained from various melanomas express keratin. Most recently, keratin expression has also been shown in cultured melanocytes of normal skin. We now report that normal human melanocytes in vivo express keratin 16 (K16) but not keratins 1, 5, 8, 10, 14, or even keratin 6, the type II partner that is normally expressed with K16 in keratinocytes. Similarly, melanocytes in vitro express K16 but not K6. Keratin 16 expression in vivo was present in basal melanocytes in specimens derived from donors (0-77 years) and from different anatomic locations, suggesting that keratin 16 is constitutively expressed by all melanocytes. It appears that keratin expression may be more prevalent than previously assumed, and that these cytoskeletal filaments may play important roles in tissues and cells other than epithelia.

DSP offer a unique method of evaluation of dermal nerve fibers. This method can be used to evaluate small nerve fibers in many neurological disorders such as MSA and PD.