Expression Of Microtubule-Associated Protein 1 In Melanocytic Nevi And Melanocytes

Background:Malignant melanoma(MM) occurs in the melanocytes and nevus cells. It is a serious form of skin cancer. Malignant melanoma not sensitivity to actinotheraphy and chemotherapy, and because of the limited success of surgical therapy, the search of effective systemic therapy for melanoma has generated intense interest over the years. Although a number of clinical and pathological factors that influence melanoma progression have been identified, to date there is no single histological, immunohistochemical, serological, or molecular marker that accurately predicts aggressive behavior of melanoma. Tumor thickness, which is considered the best predictor of melanoma aggressiveness, is not always a reliable parameter and is not relevant for more advanced primary tumors and metastatic disease. Therefore, there is a need for identification of molecular markers that predict biological behavior of melanoma cells independent of tumor thickness.Melanocytes arise from the neural crest and they are known to exhibit certain characteristics of other neural crest derivatives. For example, nerve cell has dendrite, melanocytes also have many dendrites. Similarly, melanocytes have the neural protein markers of nerve cell inherent.Microtubule- associated protein 2 is expressed abundantly in radial growth phaseand vertical growth phase melanoma cell line, but MAP2 is expressed weak or negative in metastatic melanoma.Microtubule- associated protein 1 is one of the MAPs .It facilitates microtubule nucleation, the incorporation of tubulin into microtubules and stabilizes microtubules. MAP1 also plays an important role in establishing neuron cytoskeleton ,in the growth of axons and dendrites as well as inbrain development .MAP2 and MAP1 have overlapping functions in neuronal migration and neurite outgrowth by organizing microtubules in developing neurons both for axonal and dendritic morphogenesis but more dominantly for dendritic morphogenesis.So we presume that the expression of microtubule- associated protein 1 in malignant melanoma and may be as a marker of neuronal differentiationas as well as microtubule- associated protein 2.Objective:1.To explore the expression of microtubule associated protein 1 in nevus,benign and malignant melanocytes.2. To explore the expression of microtubule associated protein 1B in malignant melanocytes of different invasions.Materials and Methods:1. To collect paraffin-embedded specimens that final diagnosis of malignant melanocytes and intradermal nevus from 2001 to 2006. These concluded 8 intradermal nevus, 6 primary malignant melanomas, and 25 metastatic melanomas. To test the expression of MAP1 in malignant melanocytes and intradermal nevus by immunohistochemistry.2.Culture the WM983A,WM1341B,WM35 of human melanoma cell lines. The total RNA of WM983A as standard preparation, to test the relative expression of MAP1B in WM983A,WM1341B,WM35 .Results:1. Analysis of the data using Fisher exact test showed strong association between intensity of MAP1 staining and the characteristics of the melanocytic lesions studied. Intradermal nevus was strongly positive for MAP1, whereas malignant melanoma showed weak staining.2. The relative expression of MAP1B in WM983A,WM1341B,WM35 were 1,0.35,0.21.Conclusions:1. MAP1 was expressed in nevus and malignant melanoma. The staining of MAP1 in nevus was stronger than malignant melanoma.2. The relative expression of MAP1B in WM983A,WM1341B,WM35 were 1,0.35,0.21. This result may be implicated with MAP1B is highly expressed during early neuronal development and gradually diminishesduring maturation. It suggests MAP1B play a important role in the mechanism of malignant melanocytes.