P53 Immunoreactivity, Ki-67 expression, and microcirculation patterns in melanoma of the iris, ciliary body, and choroid

Purpose. The major role of p53 is to modulate cell proliferation, but recently, it has been found that p53 also modulates angiogenesis through several pathways. Because both cellular proliferation and microcirculation patterns are important prognostic markers in uveal melanoma, we tested the relationships between p53 expression, the expression of the cell proliferation marker Ki-67, and the presence of various microcirculation patterns in uveal melanoma. Methods. Immunostaining of p53 and Ki-67 using the bp53.12 and the MIB-1 antibodies, respectively, were preformed in 98 uveal melanomas (18 melanomas confined to the iris, 30 ciliary body melanomas, and 50 choroidal melanomas). Percent of p53 positive cells, and the mean MIB-1 positive cell count per high power field were calculated in each section by two observers. Microcirculation patterns were assessed in adjacent PAS stained sections. Results. p53 immunoreactivity was found in 14 of the 98 melanomas. High proliferative activity and epithelioid cell type were associated with p53 immunoreactivity. However, p53 immunoreactivity was not associated with any of the microcirculation patterns or with tumor location. Conclusions. The findings suggest that alterations in p53 expression are associated with the expression of the cellular proliferation marker, Ki-67, but are not associated with the presence of microcirculation patterns.