Nine independent specimens of human skin were evaluated for the expression of MT-3. All nine specimens displayed immunoreactivity for MT-3 in the epidermis. For each specimen, the immunoreactivity for MT-3 was uniform throughout the epidermis and included staining of the basal keratinocytes ( Fig 1A). Six of the specimens exhibited moderate to strong staining for MT-3 while the other 3 displayed mild to strong intensity of staining ( Table 1). All squamous cell carcinomas (SCC) exhibited staining for MT-3 ( Table 1), five strongly ( Fig 1C), six moderately

( Fig 1E), and one mild to moderate, whereas many of the basal cell carcinomas (BCC) exhibited low staining ( Table 1) with two being totally devoid of MT-3 expression ( Fig 2F), three weakly, and the rest (five samples) were either mild or mild to moderate ( Fig 1D) in MT-3 staining. The BIRB 796 staining of MT-3 was determined

on 9 specimens of nevus. Staining for MT-3 was found for all 9 specimens, exhibited moderate to strong intensity, and was present in over 80% of the cells comprising the nevus ( Table 1, Fig 2A). Staining of MT-3 was also performed on 1 case of dysplastic nevus and 3 cases of in situ melanoma. The staining was similar to that found in the nevus with all specimens displaying moderate to strong staining in over 80% of the cells ( Table 1, Fig 2B). Staining of MT-3 was also performed on 4 cases of superficial spreading melanoma and 5 cases of deeply invasive melanoma. Again, the staining was similar to that found for GSK J4 molecular weight in situ melanoma with moderate to strong staining of MT-3 in over 80% of the melanoma cells ( Table 1, Fig 2C, D, E). Proliferating and confluent cultures of NHEK and HaCaT cells were assessed for their expression of MT-3 mRNA and protein. Real time PCR demonstrated that both resting and dividing NHEK and HaCaT cells had only background levels of MT-3 mRNA expression (Fig 3A, B). Both sets of cells were also shown to express only background levels

of MT-3 protein Inositol monophosphatase 1 (data not shown). Both the NHEK and HaCaT cells were treated with MS-275, a histone deacetylase inhibitor, and 5-aza-2′-deoxycytidine, a DNA methylation inhibitor, to determine if MT-3 expression might be silenced by a mechanism involving histone modification or DNA methylation. The results demonstrated that treatment with MS-275 was effective in restoring MT-3 mRNA expression in both the NHEK and HaCaT cells (Fig 3A,B). While MS-275 treatment was effective in both cell lines, MS-275 increased MT-3 mRNA levels in NHEK cells 10 to 20 fold greater than those of the HaCaT cell line. Treatment of the NHEK and HaCaT cells with 5-aza-2′-deoxycytidine, resulted in a small, but statistically insignificant increase in MT-3 mRNA expression for both cell types (Fig 3A, B).