Estudo da metalotioneína, óxido nítrico sintase II e óxido nítrico em neoplasias cutâneas associadas a radiação actínica

Abstract

Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most frequent skin câncer in Brazilian people. Its pathogeny is linked to the genetic effects of actinic radiation exposure, specially to the ultraviolet rays ranging from 290 to 320 nm wavelength. Metallothionein (MT) are low molecular weight proteins with high affinity for heavy metal, whose intracellular function is related to heavy metais and free radical detoxification. MT's actinic aggression protective action have been showed in others studies. On the other hand, its overexpression in different kind of tumors have been related to major aggressiveness and worst prognostic. The proposal of this study was to evaluate the expression of MT in skin câncer associated to actinic radiation. Eighteen BCC cases, five SCC and six normal skin fragments were used for this purpose. To analyze, we used the streptavidin — biotin — peroxidase technique and anti-MT primary antibody. The results showed that in the normal skin the marking situated in the epithelium basal layer. This marking extended to suprabasal layer of exposed to sun light skin (ES), near the tumor. Six cases of BCC (33%) was absent MT immunoreactivity, while all of SCC showed strong MT immunostaining . Only one SCC case (20%) and eight BCC case (44%) showed low MT expression. However, 80% of SCC cases (4/5) had intense staining, while only 22% of BCC cases (4/18) showed the same staining pattern. The average of ID for BCC was 0.69 + 0.48, and for SCC was 1.55 + .0.77. The results demonstrate that MT expression is related to SCC, suggesting a closely association with aggressive tumor.