Cyclin-dependent-kinases inhibitory proteins in normal and transformed choroidal melanocytes

Purpose : Recent studies have demonstrated the close link between oncogenes is and cell cycle machinery. Cyclin dependent kinase inhibitory proteins (C kis) have been shown to be implicated in cancer progression. We investigate d the levels of the different regulatory inhibitory proteins involved in th e GZ progression and G1/S in choroidal melanomas. Methods: Immunoblotting, immunoprecipitation and immunohistochemistry were per formed on human choroidal cell lines and human choroidal tumors. Results : Our findings suggested a lack of expression of Cdk inhibitor p21 in two of three melanoma cell lines and a striking underexpression of p27 i n the three transformed cell lines. The p16 level was found to be almost th e same in both normal and transformed cells, a loss of p16-Cdk4 interaction was observed in two of the three melanoma cell lines. In immunohistochemis try, nuclear positivity for p16 was observed in six tumors. Nuclear positiv ity for p21 was observed in five tumors. All of theses tumors had scleral i nvasion (p = 0,003). Nuclear positivity for p27 was observed in only two tu mors. Conclusion : Our results demonstrate that immunoreactivity for p16, p21 and p27 could be implicated in progression of melanoma tumors. More cases are required to further clarify this issue.