Expression of the c-kit receptor in choroidal melanomas.
The KIT gene encodes c-kit, a transmembrane receptor that has tyrosine kinase activity and plays a role in haematopoiesis, gametogenesis and melanogenesis. The c-kit protein is found in normal cutaneous and choroidal melanocytes, and there is evidence that expression is lost in melanoma. Expression of c-kit was analysed in 57 paraffin-embedded sections of choroidal melanoma specimens and three choroidal melanoma cell lines using immunochemistry and Western blotting. Of the tumour specimens, 75% stained positively for c-kit with a membrane pattern of reactivity. Of the six patients who underwent proton beam therapy before enucleation, five tumours exhibited no c-kit immunoreactivity and the other tumour demonstrated weak staining. Of the three melanoma cell lines used, c-kit expression was observed in only one. No correlations between c-kit positivity and parameters such as cell type, largest macroscopic tumour dimension, scleral invasion or pigmentation were observed. In contrast, a significant positive association was found between c-kit staining and mitotic activity (P = 0.02). However, c-kit expression did not significantly influence survival when evaluated by univariate analysis. In conclusion, c-kit is expressed in most choroidal melanoma tumours. Further analysis should provide new insights into the mechanisms underlying the molecular and cellular changes in choroidal melanomas.
Mouriaux
Frédéric
F
Department of Ophthalmology, Lens Hospital, 62307 Lens, France. fmouriaux@ch-lens.fr
Kherrouche
Zoulika
Z
Maurage
Claude-Alain
CA
Demailly
François-Xavier
FX
Labalette
Pierre
P
Saule
Simon
S
D015153:Blotting, Western; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002830:Choroid Neoplasms / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008545:Melanoma / Q000378:metabolism*; D008938:Mitosis; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis*; D013997:Time Factors
D019009:Proto-Oncogene Proteins c-kit