Abstract
Abstract: :
Purpose: The protein encoded by the microphthalmia (mi) gene is a transcription factor essential for the development and survival of melanocytes. It serves as a master regulator in modulating extracellular signals. Because of its central role in melanocytes survival and to assess its potential use as a histopathological marker for melanoma, Mitf expression was examined in human choroidal melanomas. Methods: 57 paraffin-embedded sections of choroidal melanoma specimens and 2 choroidal melanoma cell lines were analyzed using immunochemistry and RT-PCR. Normal choroids and normal choroidal melanocyte cells were used as control. Results: 65% specimens stained positively for Mitf with a nuclear pattern of reactivity. Mitf-M and Mitf-A isoforms were detected in all specimens examined with variable levels. No correlation between Mitf-positivity and parameters such as cell type, LTD, sclera invasion, mitotic figures was observed. In contrast, a significant negative association was found between Mitf staining and the pigmentation (p=0.02). Conclusion: Further analysis should provide new insights into the mechanisms underlying the molecular and cellular changes of choroidal melanomas.
Keywords: 345 choroid • 605 transcription factors • 610 tumors