Abstract
In the present study we analyzed, by immunohistochemistry, a panel of human melanomas for protein expression of the cyclin-dependent kinase (cdk) inhibitor p27
Kip1
and evaluated whether deregulated expression correlates with clinical outcome for this type of cancer. We found that p27
Kip1
was strongly expressed by normal melanocytes and benign nevi, whereas in malignant melanoma, a heterogeneous expression pattern was observed. In the case of nodular melanomas, the level of p27
Kip1
was found to correlate significantly with the thickness of the tumor, with less protein expressed in thicker lesions. We also found that patients having tumors with fewer than 5% p27
Kip1
-staining cells had a significantly higher risk of early relapse of their disease compared with those expressing moderate or high levels. In contrast, the level of p27
Kip1
did not correlate with tumor thickness or disease-free survival in patients with superficial spreading melanomas, suggesting that p27
Kip1
may play different roles in these two major pathological subgroups of malignant melanoma. Furthermore, p27
Kip1
did not appear to have an influence on overall survival for either subgroup. When we examined the combined effect of p21
WAF1/CIP1
(another cdk inhibitor) and p27
Kip1
on clinical outcome, we found that analysis of these two cdk inhibitors together may have greater prognostic potential than either alone. In conclusion, our results suggest that virtually complete loss of p27
Kip1
protein expression has potential importance as a prognostic indicator of early relapse in patients with nodular melanoma. The results, furthermore, underscore the value of analyzing multiple cell cycle regulatory proteins to obtain the most reliable indication of prognosis.
